WorldWideScience

Sample records for plasma sheet particles

  1. Thin current sheets in collisionless plasma: Equilibrium structure, plasma instabilities, and particle acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Zelenyi, L. M.; Malova, H. V.; Artemyev, A. V.; Popov, V. Yu.; Petrukovich, A. A. [Russian Academy of Sciences, Space Research Institute (Russian Federation)

    2011-02-15

    The review is devoted to plasma structures with an extremely small transverse size, namely, thin current sheets that have been discovered and investigated by spacecraft observations in the Earth's magnetotail in the last few decades. The formation of current sheets is attributed to complicated dynamic processes occurring in a collisionless space plasma during geomagnetic perturbations and near the magnetic reconnection regions. The models that describe thin current structures in the Earth's magnetotail are reviewed. They are based on the assumption of the quasi-adiabatic ion dynamics in a relatively weak magnetic field of the magnetotail neutral sheet, where the ions can become unmagnetized. It is shown that the ion distribution can be represented as a function of the integrals of particle motion-the total energy and quasi-adiabatic invariant. Various modifications of the initial equilibrium are considered that are obtained with allowance for the currents of magnetized electrons, the contribution of oxygen ions, the asymmetry of plasma sources, and the effects related to the non-Maxwellian particle distributions. The theoretical results are compared with the observational data from the Cluster spacecraft mission. Various plasma instabilities developing in thin current sheets are investigated. The evolution of the tearing mode is analyzed, and the parameter range in which the mode can grow are determined. The paradox of complete stabilization of the tearing mode in current sheets with a nonzero normal magnetic field component is thereby resolved based on the quasi-adiabatic model. It is shown that, over a wide range of current sheet parameters and the propagation directions of large-scale unstable waves, various modified drift instabilities-kink and sausage modes-can develop in the system. Based on the concept of a turbulent electromagnetic field excited as a result of the development and saturation of unstable waves, a mechanism for charged particle

  2. Sounding of the plasma sheet in the deep geomagnetic tail using energetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Daly, P.W.; Wenzel, K.; Sanderson, T.R.

    1984-10-01

    Energetic ions (E>35 keV) at 90/sup 0/ to the magnetic field line are measured on ISEE-3 in the distant geomagnetic tail and are used as tracers of the particle density during two encounters with the plasma sheet at 210 and 128 earth radii from the earth. Because of the finite gyroradius (2400 km) of these (assumed) protons, different orientation about the magnetic field measure the intensity of different locations, allowing a separation of spatial from temporal variations. Density contour maps of the plasma hseet are constructed, demonstrating the wavy nature of this regime, as well as the existence of density layers within it.

  3. Three-dimensional particle simulation of plasma instabilities and collisionless reconnection in a current sheet

    Energy Technology Data Exchange (ETDEWEB)

    Horiuchi, Ritoku; Sato, Tetsuya [Theory and Computer Simulation Center, National Inst. for Fusion Science, Toki, Gifu (Japan)

    1999-06-01

    Generation of anomalous resistivity and dynamical development of collisionless reconnection in the vicinity of a magnetically neutral sheet are investigated by means of a three-dimensional particle simulation. For no external driving source, two different types of plasma instabilities are excited in the current layer. The lower hybrid drift instability (LHDI) is observed to grow in the periphery of current layer in an early period, while a drift kink instability (DKI) is triggered at the neutral sheet in a late period as a result of the nonlinear deformation of the current sheet by the LHDI. A reconnection electric field grows at the neutral sheet in accordance with the excitation of the DKI. When an external driving field exists, the convective electric field penetrates into the current layer through the particle kinetic effect and collisionless reconnection is triggered by the convective electric field earlier than the DKI is excited. It is also found that the anisotropic ion distribution is formed through the anomalous ion heating by the DKI. (author)

  4. Collective dynamics of bursty particle precipitation initiating in the inner and outer plasma sheet

    Science.gov (United States)

    Uritsky, V. M.; Donovan, E.; Klimas, A. J.; Spanswick, E.

    2009-02-01

    Using multiscale spatiotemporal analysis of bursty precipitation events in the nighttime aurora as seen by the POLAR UVI instrument, we report a set of new statistical signatures of high- and low-latitude auroral activity, signaling a strongly non-uniform distribution of dissipation mechanism in the plasma sheet. We show that small-scale electron emission events that initiate in the equatorward portion of the nighttime auroral oval (scaling mode A1) have systematically steeper power-law slopes of energy, power, area, and lifetime probability distributions compared to the events that initiate at higher latitudes (mode B). The low-latitude group of events also contain a small but energetically important subpopulation of substorm-scale disturbances (mode A2) described by anomalously low distribution exponents characteristic of barely stable thermodynamic systems that are prone to large-scale sporadic reorganization. The high latitude events (mode organized critical (SOC) behavior. The low- and high latitude events have distinct inter-trigger time statistics, and are characterized by significantly different MLT distributions. Based on these results we conjecture that the inner and outer portions of the plasma sheet are associated with two (or more) mechanisms of collective dynamics that may represent an interplay between current disruption and magnetic reconnection scenarios of bursty energy conversion in the magnetotail.

  5. Thermomechanical processing of plasma sprayed intermetallic sheets

    Energy Technology Data Exchange (ETDEWEB)

    Hajaligol, Mohammad R. (Midlothian, VA); Scorey, Clive (Cheshire, CT); Sikka, Vinod K. (Oak Ridge, TN); Deevi, Seetharama C. (Midlothian, VA); Fleischhauer, Grier (Midlothian, VA); Lilly, Jr., A. Clifton (Chesterfield, VA); German, Randall M. (State College, PA)

    2001-01-01

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  6. The Dynamical Generation of Current Sheets in Astrophysical Plasma Turbulence

    CERN Document Server

    Howes, Gregory G

    2016-01-01

    Turbulence profoundly affects particle transport and plasma heating in many astrophysical plasma environments, from galaxy clusters to the solar corona and solar wind to Earth's magnetosphere. Both fluid and kinetic simulations of plasma turbulence ubiquitously generate coherent structures, in the form of current sheets, at small scales, and the locations of these current sheets appear to be associated with enhanced rates of dissipation of the turbulent energy. Therefore, illuminating the origin and nature of these current sheets is critical to identifying the dominant physical mechanisms of dissipation, a primary aim at the forefront of plasma turbulence research. Here we present evidence from nonlinear gyrokinetic simulations that strong nonlinear interactions between counterpropagating Alfven waves, or strong Alfven wave collisions, are a natural mechanism for the generation of current sheets in plasma turbulence. Furthermore, we conceptually explain this current sheet development in terms of the nonlinear...

  7. Sheet Plasma Produced by Hollow Cathode Discharge

    Institute of Scientific and Technical Information of China (English)

    张龙; 张厚先; 杨宣宗; 冯春华; 乔宾; 王龙

    2003-01-01

    A sheet plasma is produced by a hollow cathode discharge under an axial magnetic field.The plasma is about 40cm in length,4 cm in width and 1cm in thickness.The electron density is about 108cm-3.The hollow cathode is made to be shallow with a large opening,which is different from the ordinary deep hollow cathode.A Langmuir probe is used to detect the plasma.The electron density and the spatial distribution of the plasma change when voltage,pressure and the magnetic field vary.A peak and a data fluctuation at about 200 G-300 G are observed in the variation of electron density(or thickness of the sheet plasma)with the magnetic field.Our work will be helpful in characterizing the sheet plasma and will make the production of dense sheet plasma more controllable.

  8. Dynamic of Current Sheets and Their Associated Particle Energization

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hui [Los Alamos National Laboratory; Guo, Fan [Los Alamos National Laboratory; Makwan, Kirit [Univ. Chicago; Li, Xiaocan [Los Alamos National Laboratory; Zhandrin, Vladimir [Univ. Washington; Daughton, William Scott [Los Alamos National Laboratory

    2015-08-19

    Magnetic reconnection in current sheets has relevance to Earth's magnetosphere, solar flares, high-energy astrophysics (pulsar wind nebula (e.g. Crab Nebula), gamma-ray bursts, black hole jets), and laboratory plasma/fusion. Data are shown for several cases with varying values of configuration energy Ec and β. Several conclusions were drawn: Depending on the “configuration energy”, the formation, shape, and lifetime of current sheets can vary. Plasma condition (configuration, β, driving, etc.) strongly affect the efficiency of particle acceleration. For low β and general “configuration energy”, particle heating is expected. For low β, large and long-lived current sheets, it is possible to produce highly non-thermal particles via collisionless plasmoid reconnection.

  9. Dynamic of particle-laden liquid sheet

    Science.gov (United States)

    Sauret, Alban; Jop, Pierre; Troger, Anthony

    2016-11-01

    Many industrial processes, such as surface coating or liquid transport in tubes, involve liquid sheets or thin liquid films of suspensions. In these situations, the thickness of the liquid film becomes comparable to the particle size, which leads to unexpected dynamics. In addition, the classical constitutive rheological law cannot be applied as the continuum approximation is no longer valid. Here, we consider experimentally a transient free liquid sheet that expands radially. We characterize the influence of the particles on the shape of the liquid film as a function of time and the atomization process. We highlight that the presence of particles modifies the thickness and the stability of the liquid sheet. Our study suggests that the influence of particles through capillary effects can modify significantly the dynamics of processes that involve suspensions and particles confined in liquid films.

  10. Gyrophase bunched ions in the plasma sheet

    Science.gov (United States)

    Wang, Zhiqiang; Zhai, Hao; Gao, Zhuxiu; Huang, Chaoyan

    2017-01-01

    Gyrophase bunched ions were first detected in the upstream region of the Earth's bow shock in the early 1980s which is formed by the microphysical process associated with reflected solar wind ions at the bow shock. Inside the magnetosphere, the results of computer simulations demonstrated that nonlinear wave-particle interaction can also result in the gyrophase bunching of particles. However, to date direct observations barely exist regarding this issue occurred inside the magnetosphere. In this paper, we report for the first time an event of gyrophase bunched ions observed in the near-Earth plasma sheet. The nongyrotropic distributions of ions were closely accompanied with the electromagnetic waves at the oxygen cyclotron frequency. The phase of bunched ions and the phase of waves mainly have very narrow phase differences (helicity with respect to the propagation direction, which agrees with the characteristic of electromagnetic ion cyclotron waves. The observation of O+ ions composition suggests that the oxygen band waves are excited due to the enhancements of the O+ ion density. This study suggests that the gyrophase bunching is a significant nonlinear effect that exists not only in the bow shock but also in the inner magnetosphere.

  11. Plasma and particles

    Science.gov (United States)

    Špatenka, Petr; Vacková, Tat'ana; Nováček, Vojtěch; Jeníková, Zdenka

    2016-12-01

    Plasma has been proved as a standard industrial method for surface treatment of solid bulk materials. Recently plasma has also been used in connection with production, treatment and functionalization of powder and granulate materials. Functionalization was originally developed for hydrophylization of hydrophobic surfaces of particles made from various materials. An industrial scale device with a capacity of several hundreds of tons per year based on plasma treatment will be presented. As examples of the applications are given plasma treated polyethylene powder dispersed in the water; and very good adhesion of polymer powders to metals or glass, which is promising for development of new generation of thermoplastic composites.

  12. Particle acceleration by plasma

    CERN Document Server

    Ogata, A

    2002-01-01

    Plasma acceleration is carried out by using potential of plasma wave. It is classified by generation method of plasma wave such as the laser wake-field acceleration and the beat wave acceleration. Other method using electron beam is named the plasma wake-field acceleration (or beam wake-field acceleration). In this paper, electron acceleration by laser wake-field in gas plasma, ion source by laser radiation of solid target and nanoion beam generation by one component of plasma in trap are explained. It is an applicable method that ions, which run out from the solid target irradiated by laser, are used as ion source of accelerator. The experimental system using 800 nm laser, 50 mJ pulse energy and 50 fs pulse width was studied. The laser intensity is 4x10 sup 1 sup 6 Wcm sup - sup 2 at the focus. The target film of metal and organic substance film was used. When laser irradiated Al target, two particles generated, in front and backward. It is new fact that the neutral particle was obtained in front, because it...

  13. Geomagnetic activity effects on plasma sheet energy conversion

    Directory of Open Access Journals (Sweden)

    M. Hamrin

    2010-10-01

    Full Text Available In this article we use three years (2001, 2002, and 2004 of Cluster plasma sheet data to investigate what happens to localized energy conversion regions (ECRs in the plasma sheet during times of high magnetospheric activity. By examining variations in the power density, E·J, where E is the electric field and J is the current density obtained by Cluster, we have studied the influence on Concentrated Load Regions (CLRs and Concentrated Generator Regions (CGRs from variations in the geomagnetic disturbance level as expressed by the Kp, the AE, and the Dst indices. We find that the ECR occurrence frequency increases during higher magnetospheric activities, and that the ECRs become stronger. This is true both for CLRs and for CGRs, and the localized energy conversion therefore concerns energy conversion in both directions between the particles and the fields in the plasma sheet. A higher geomagnetic activity hence increases the general level of energy conversion in the plasma sheet. Moreover, we have shown that CLRs live longer during magnetically disturbed times, hence converting more electromagnetic energy. The CGR lifetime, on the other hand, seems to be unaffected by the geomagnetic activity level. The evidence for increased energy conversion during geomagnetically disturbed times is most clear for Kp and for AE, but there are also some indications that energy conversion increases during large negative Dst. This is consistent with the plasma sheet magnetically mapping to the auroral zone, and therefore being more tightly coupled to auroral activities and variations in the AE and Kp indices, than to variations in the ring current region as described by the Dst index.

  14. Energetic electron spectra in Saturn's plasma sheet

    Science.gov (United States)

    Carbary, J. F.; Paranicas, C.; Mitchell, D. G.; Krimigis, S. M.; Krupp, N.

    2011-07-01

    The differential spectra of energetic electrons (27-400 keV) in Saturn's plasma sheet can be characterized by power law or kappa distributions. Using all available fluxes from 2005 to 2010, fits to these distributions reveal a striking and consistent pattern of radial dependence in Saturn's plasma sheet (∣z∣ constant throughout the Cassini mission. Inward of about 10 RS, the presence of the electron radiation belts and losses of lower-energy electrons to the gas and grain environment give rise to the very hard spectra in the inner magnetosphere, while the hard spectra in the outer magnetosphere may derive from auroral acceleration at high latitudes. The gradual softening of the spectra from 20 to 10 RS is explained by inward radial diffusion.

  15. On the nature of the plasma sheet boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Hones, E.W. Jr. (Mission Research Corp., Los Alamos, NM (USA) Los Alamos National Lab., NM (USA))

    1990-01-01

    The regions of the plasma sheet adjacent to the north and south lobes of the magnetotail have been described by many experimenters as locations of beams of energetic ions and fast-moving plasma directed primarily earthward and tailward along magnetic field lines. Measurements taken as satellites passed through one or the other of these boundary layers have frequently revealed near-earth mirroring of ions and a vertical segregation of velocities of both earthward-moving and mirroring ions with the fastest ions being found nearest the lobe-plasma sheet interface. These are features expected for particles from a distant tail source {bar E} {times} {bar B} drifting in a dawn-to-dusk electric field and are consistent with the source being a magnetic reconnection region. The plasma sheet boundary layers are thus understood as separatrix layers, bounded at their lobeward surfaces by the separatrices from the distant neutral line. This paper will review the observations that support this interpretation. 10 refs., 7 figs.

  16. THIN CURRENT SHEETS AND ASSOCIATED ELECTRON HEATING IN TURBULENT SPACE PLASMA

    Energy Technology Data Exchange (ETDEWEB)

    Chasapis, A.; Retinò, A.; Sahraoui, F.; Canu, P. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, Palaiseau, F-91128 (France); Vaivads, A.; Khotyaintsev, Yu. V. [Swedish Institute of Space Physics, Uppsala (Sweden); Sundkvist, D. [Space Sciences Laboratory, University of California, Berkeley, CA (United States); Greco, A. [Dipartimento di Fisica, Universita della Calabria (Italy); Sorriso-Valvo, L., E-mail: alexandros.chasapis@lpp.polytechnique.fr [IMIP-CNR, U.O.S. LICRYL di Cosenza (Italy)

    2015-05-01

    Intermittent structures, such as thin current sheets, are abundant in turbulent plasmas. Numerical simulations indicate that such current sheets are important sites of energy dissipation and particle heating occurring at kinetic scales. However, direct evidence of dissipation and associated heating within current sheets is scarce. Here, we show a new statistical study of local electron heating within proton-scale current sheets by using high-resolution spacecraft data. Current sheets are detected using the Partial Variance of Increments (PVI) method which identifies regions of strong intermittency. We find that strong electron heating occurs in high PVI (>3) current sheets while no significant heating occurs in low PVI cases (<3), indicating that the former are dominant for energy dissipation. Current sheets corresponding to very high PVI (>5) show the strongest heating and most of the time are consistent with ongoing magnetic reconnection. This suggests that reconnection is important for electron heating and dissipation at kinetic scales in turbulent plasmas.

  17. Plasma Relaxation Dynamics Moderated by Current Sheets

    Science.gov (United States)

    Dewar, Robert; Bhattacharjee, Amitava; Yoshida, Zensho

    2014-10-01

    Ideal magnetohydrodynamics (IMHD) is strongly constrained by an infinite number of microscopic constraints expressing mass, entropy and magnetic flux conservation in each infinitesimal fluid element, the latter preventing magnetic reconnection. By contrast, in the Taylor-relaxed equilibrium model all these constraints are relaxed save for global magnetic flux and helicity. A Lagrangian is presented that leads to a new variational formulation of magnetized fluid dynamics, relaxed MHD (RxMHD), all static solutions of which are Taylor equilibrium states. By postulating that some long-lived macroscopic current sheets can act as barriers to relaxation, separating the plasma into multiple relaxation regions, a further generalization, multi-relaxed MHD (MRxMHD), is developed. These concepts are illustrated using a simple two-region slab model similar to that proposed by Hahm and Kulsrud--the formation of an initial shielding current sheet after perturbation by boundary rippling is calculated using MRxMHD and the final island state, after the current sheet has relaxed through a reconnection sequence, is calculated using RxMHD. Australian Research Council Grant DP110102881.

  18. Thin Current Sheets and Associated Electron Heating in Turbulent Space Plasma

    Science.gov (United States)

    Chasapis, A.; Retinò, A.; Sahraoui, F.; Vaivads, A.; Khotyaintsev, Yu. V.; Sundkvist, D.; Greco, A.; Sorriso-Valvo, L.; Canu, P.

    2015-05-01

    Intermittent structures, such as thin current sheets, are abundant in turbulent plasmas. Numerical simulations indicate that such current sheets are important sites of energy dissipation and particle heating occurring at kinetic scales. However, direct evidence of dissipation and associated heating within current sheets is scarce. Here, we show a new statistical study of local electron heating within proton-scale current sheets by using high-resolution spacecraft data. Current sheets are detected using the Partial Variance of Increments (PVI) method which identifies regions of strong intermittency. We find that strong electron heating occurs in high PVI (>3) current sheets while no significant heating occurs in low PVI cases (5) show the strongest heating and most of the time are consistent with ongoing magnetic reconnection. This suggests that reconnection is important for electron heating and dissipation at kinetic scales in turbulent plasmas.

  19. High-beta plasma blobs in the morningside plasma sheet

    Directory of Open Access Journals (Sweden)

    G. Haerendel

    Full Text Available Equator-S frequently encountered, i.e. on 30% of the orbits between 1 March and 17 April 1998, strong variations of the magnetic field strength of typically 5–15-min duration outside about 9RE during the late-night/early-morning hours. Very high-plasma beta values were found, varying between 1 and 10 or more. Close conjunctions between Equator-S and Geotail revealed the spatial structure of these "plasma blobs" and their lifetime. They are typically 5–10° wide in longitude and have an antisymmetric plasma or magnetic pressure distribution with respect to the equator, while being altogether low-latitude phenomena 
    (≤ 15°. They drift slowly sunward, exchange plasma across the equator and have a lifetime of at least 15–30 min. While their spatial structure may be due to some sort of mirror instability, little is known about the origin of the high-beta plasma. It is speculated that the morningside boundary layer somewhat further tailward may be the source of this plasma. This would be consistent with the preference of the plasma blobs to occur during quiet conditions, although they are also found during substorm periods. The relation to auroral phenomena in the morningside oval is uncertain. The energy deposition may be mostly too weak to generate a visible signature. However, patchy aurora remains a candidate for more disturbed periods.

    Key words. Magnetospheric physics (plasma convection; plasma sheet; plasma waves and instabilities

  20. EIDOSCOPE: particle acceleration at plasma boundaries

    Science.gov (United States)

    Vaivads, A.; Andersson, G.; Bale, S. D.; Cully, C. M.; De Keyser, J.; Fujimoto, M.; Grahn, S.; Haaland, S.; Ji, H.; Khotyaintsev, Yu. V.; Lazarian, A.; Lavraud, B.; Mann, I. R.; Nakamura, R.; Nakamura, T. K. M.; Narita, Y.; Retinò, A.; Sahraoui, F.; Schekochihin, A.; Schwartz, S. J.; Shinohara, I.; Sorriso-Valvo, L.

    2012-04-01

    We describe the mission concept of how ESA can make a major contribution to the Japanese Canadian multi-spacecraft mission SCOPE by adding one cost-effective spacecraft EIDO (Electron and Ion Dynamics Observatory), which has a comprehensive and optimized plasma payload to address the physics of particle acceleration. The combined mission EIDOSCOPE will distinguish amongst and quantify the governing processes of particle acceleration at several important plasma boundaries and their associated boundary layers: collisionless shocks, plasma jet fronts, thin current sheets and turbulent boundary layers. Particle acceleration and associated cross-scale coupling is one of the key outstanding topics to be addressed in the Plasma Universe. The very important science questions that only the combined EIDOSCOPE mission will be able to tackle are: 1) Quantitatively, what are the processes and efficiencies with which both electrons and ions are selectively injected and subsequently accelerated by collisionless shocks? 2) How does small-scale electron and ion acceleration at jet fronts due to kinetic processes couple simultaneously to large scale acceleration due to fluid (MHD) mechanisms? 3) How does multi-scale coupling govern acceleration mechanisms at electron, ion and fluid scales in thin current sheets? 4) How do particle acceleration processes inside turbulent boundary layers depend on turbulence properties at ion/electron scales? EIDO particle instruments are capable of resolving full 3D particle distribution functions in both thermal and suprathermal regimes and at high enough temporal resolution to resolve the relevant scales even in very dynamic plasma processes. The EIDO spin axis is designed to be sun-pointing, allowing EIDO to carry out the most sensitive electric field measurements ever accomplished in the outer magnetosphere. Combined with a nearby SCOPE Far Daughter satellite, EIDO will form a second pair (in addition to SCOPE Mother-Near Daughter) of closely

  1. Particle position and velocity measurement in dusty plasmas using particle tracking velocimetry

    Science.gov (United States)

    Feng, Yan; Goree, J.; Haralson, Zach; Wong, Chun-Shang; Kananovich, A.; Li, Wei

    2016-06-01

    > Methods of imaging and image analysis are presented for dusty plasma experiments. Micron-sized polymer spheres, electrically suspended in a partially ionized gas, are illuminated by a sheet of laser light and imaged by video cameras. Image analysis methods yield particle positions and velocities of individual particles in each video image. Methods to minimize errors in the particle positions and velocities, which are now commonly used in the dusty plasma community, are described.

  2. New aspects of plasma sheet dynamics - MHD and kinetic theory

    Directory of Open Access Journals (Sweden)

    H. Wiechen

    Full Text Available Magnetic reconnection is a process of fundamental importance for the dynamics of the Earth's plasma sheet. In this context, the development of thin current sheets in the near-Earth plasma sheet is a topic of special interest because they could be a possible cause of microscopic fluctuations acting as collective non-idealness from a macroscopic point of view. Simulations of the near-Earth plasma sheet including boundary perturbations due to localized inflow through the northern (or southern plasma sheet boundary show developing thin current sheets in the near-Earth plasma sheet about 810 RE tailwards of the Earth. This location is largely independent from the localization of the perturbation. The second part of the paper deals with the problem of the macroscopic non-ideal consequences of microscopic fluctuations. A new model is presented that allows the quantitative calculation of macroscopic non-idealness without considering details of microscopic instabilities or turbulence. This model is only based on the assumption of a strongly fluctuating, mixing dynamics on microscopic scales in phase space. The result of this approach is an expression for anomalous non-idealness formally similar to the Krook resistivity but now describing the macroscopic consequences of collective microscopic fluctuations, not of collisions.

    Key words. Magnetospheric physics (plasma sheet · Space plasma physics (kinetic and MHD theory; magnetic reconnection

  3. Ion Beams in the Plasma Sheet Boundary Layer

    Science.gov (United States)

    Birn, J.; Hesse, M.; Runov, A.; Zhou, X.

    2015-12-01

    We explore characteristics of energetic particles in the plasma sheet boundary layer associated with dipolarization events, based on simulations and observations. The simulations use the electromagnetic fields of an MHD simulation of magnetotail reconnection and flow bursts as basis for test particle tracing. They are complemented by self-consistent fully electrodynamic particle-in-cell (PIC) simulations. The test particle simulations confirm that crescent shaped earthward flowing ion velocity distributions with strong perpendicular anisotropy can be generated as a consequence of near tail reconnection, associated with earthward flows and propagating magnetic field dipolarization fronts. Both PIC and test particle simulations show that the ion distribution in the outflow region close to the reconnection site also consist of a beam superposed on an undisturbed population; this beam, however, does not show strong perpendicular anisotropy. This suggests that the crescent shape is created by quasi-adiabatic deformation from ion motion along the magnetic field toward higher field strength. The simulation results compare favorably with ``Time History of Events and Macroscale Interactions during Substorms" (THEMIS) observations.

  4. The statistical studies of the inner boundary of plasma sheet

    Directory of Open Access Journals (Sweden)

    J. B. Cao

    2011-02-01

    Full Text Available The penetration of plasma sheet ions into the inner magnetosphere is very important to the inner magnetospheric dynamics since plasma sheet ions are one of the major particle sources of ring current during storm times. However, the direct observations of the inner boundary of the plasma sheet are fairly rare due to the limited number of satellites in near equatorial orbits outside 6.6 RE. In this paper, we used the ion data recorded by TC-1 from 2004 to 2006 to study the distribution of inner boundary of ion plasma sheet (IBIPS and for the first time show the observational distribution of IBIPS in the equatorial plane. The IBIPS has a dawn-dusk asymmetry, being farthest to the Earth in the 06:00 08:00 LT bin and closest to the Earth in the 18:00–20:00 LT bin. Besides, the IBIPS has also a day-night asymmetry, which may be due to the fact that the ions on the dayside are exposed more time to loss mechanisms on their drift paths. The radial distance of IBIPS decrease generally with the increase of Kp index. The mean radial distance of IBIPS is basically larger than 6.6 RE during quiet times and smaller than 6.6 RE during active times. When the strength of convection electric field increases, the inward shift of IBIPS is most significant on the night side (22:00–02:00 LT. For Kp ≤ 0+, only 16% of IBIPSs penetrate inside the geosynchronous orbit. For 2 ≤ Kp < 3+, however, 70% of IBIPSs penetrate inside the geosynchronous orbit. The IBIPS has weak correlations with the AE and Dst indexes. The average correlation coefficient between Ri and Kp is −0.58 while the correlation coefficient between Ri and AE/Dst is only −0.29/0.17. The correlation coefficients are local time dependent. Particularly, Ri and Kp are highly correlated (r=−0.72 in the night sector, meaning that the radial distance of IBIPS

  5. Central Plasma Sheet Ion Properties as Inferred from Ionospheric Observations

    Science.gov (United States)

    Wing, Simon; Newell, Patrick T.

    1998-01-01

    A method of inferring central plasma sheet (CPS) temperature, density, and pressure from ionospheric observations is developed. The advantage of this method over in situ measurements is that the CPS can be studied in its entirely, rather than only in fragments. As a result, for the first time, comprehensive two-dimensional equatorial maps of CPS pressure, density, and temperature within the isotropic plasma sheet are produced. These particle properties are calculated from data taken by the Special Sensor for Precipitating Particles, version 4 (SSJ4) particle instruments onboard DMSP F8, F9, F10, and F11 satellites during the entire year of 1992. Ion spectra occurring in conjunction with electron acceleration events are specifically excluded. Because of the variability of magnetotail stretching, the mapping to the plasma sheet is done using a modified Tsyganenko [1989] magnetic field model (T89) adjusted to agree with the actual magnetotail stretch at observation time. The latter is inferred with a high degree of accuracy (correlation coefficient -0.9) from the latitude of the DMSP b2i boundary (equivalent to the ion isotropy boundary). The results show that temperature, pressure, and density all exhibit dawn-dusk asymmetries unresolved with previous measurements. The ion temperature peaks near the midnight meridian. This peak, which has been associated with bursty bulk flow events, widens in the Y direction with increased activity. The temperature is higher at dusk than at dawn, and this asymmetry increases with decreasing distance from the Earth. In contrast, the density is higher at dawn than at dusk, and there appears to be a density enhancement in the low-latitude boundary layer regions which increases with decreasing magnetic activity. In the near-Earth regions, the pressure is higher at dusk than at dawn, but this asymmetry weakens with increasing distance from the Earth and may even reverse so that at distances X less than approx. 10 to -12 R(sub E

  6. Magnetic turbulence in the plasma sheet

    CERN Document Server

    Vörös, Z; Nakamura, R; Runov, A; Zhang, T L; Eichelberger, H U; Treumann, R A; Georgescu, E; Balogh, A; Klecker, B; R`eme, H

    2004-01-01

    Small-scale magnetic turbulence observed by the Cluster spacecraft in the plasma sheet is investigated by means of a wavelet estimator suitable for detecting distinct scaling characteristics even in noisy measurements. The spectral estimators used for this purpose are affected by a frequency dependent bias. The variances of the wavelet coefficients, however, match the power-law shaped spectra, which makes the wavelet estimator essentially unbiased. These scaling characteristics of the magnetic field data appear to be essentially non-steady and intermittent. The scaling properties of bursty bulk flow (BBF) and non-BBF associated magnetic fluctuations are analysed with the aim of understanding processes of energy transfer between scales. Small-scale ($\\sim 0.08-0.3$ s) magnetic fluctuations having the same scaling index $\\alpha \\sim 2.6$ as the large-scale ($\\sim 0.7-5$ s) magnetic fluctuations occur during BBF-associated periods. During non-BBF associated periods the energy transfer to small scales is absent, ...

  7. Simulation of Au particle interaction on graphene sheets

    Science.gov (United States)

    Mcleod, A.; Vernon, K. C.; Rider, A. E.; Ostrikov, K.

    2013-09-01

    The interaction of Au particles with few layer graphene is of interest for the formation of the next generation of sensing devices 1. In this paper we investigate the coupling of single gold nanoparticles to a graphene sheet, and multiple gold nanoparticles with a graphene sheet using COMSOL Multiphysics. By using these simulations we are able to determine the electric field strength and associated hot-spots for various gold nanoparticle-graphene systems. The Au nanoparticles were modelled as 8 nm diameter spheres on 1.5 nm thick (5 layers) graphene, with properties of graphene obtained from the refractive index data of Weber 2 and the Au refractive index data from Palik 3. The field was incident along the plane of the sheet with polarisation tested for both s and p. The study showed strong localised interaction between the Au and graphene with limited spread; however the double particle case where the graphene sheet separated two Au nanoparticles showed distinct interaction between the particles and graphene. An offset was introduced (up to 4 nm) resulting in much reduced coupling between the opposed particles as the distance apart increased. Findings currently suggest that the graphene layer has limited interaction with incident fields with a single particle present whilst reducing the coupling region to a very fine area when opposing particles are involved. It is hoped that the results of this research will provide insight into graphene-plasmon interactions and spur the development of the next generation of sensing devices.

  8. Occurrence and location of concentrated load and generator regions observed by Cluster in the plasma sheet

    Directory of Open Access Journals (Sweden)

    M. Hamrin

    2009-11-01

    Full Text Available Here, and in a companion paper by Hamrin et al. (2009 [Scale size and life time of energy conversion regions observed by Cluster in the plasma sheet], we investigate localized energy conversion regions (ECRs in the Earth's plasma sheet. In total we have studied 151 ECRs within 660 h of plasma sheet data from the summer and fall of 2001 when Cluster was close to apogee at an altitude of about 15–20 RE. Cluster offers appropriate conditions for the investigation of energy conversion by the evaluation of the power density, E·J, where E is the electric field and J the current density. From the sign of the power density, we have identified more than three times as many Concentrated Load Regions (CLRs as Concentrated Generator Regions (CGRs. We also note that the CLRs appear to be stronger. To our knowledge, these are the first in situ observations confirming the general notion of the plasma sheet, on the average, behaving as a load. At the same time the plasma sheet appears to be highly structured, with energy conversion occurring in both directions between the fields and the particles. From our data we also find that the CLRs appear to be located closer to the neutral sheet, while CGRs prefer locations towards the plasma sheet boundary layer (PSBL. For both CLRs and CGRs, E and J in the GSM y (cross-tail direction dominate the total power density, even though the z contribution occasionally can be significant. The prevalence of the y-direction seems to be weaker for the CGRs, possibly related to a higher fluctuation level near the PSBL.

  9. Thickness of Heliospheric Current and Plasma Sheets: Dependence on Distance

    Science.gov (United States)

    Zhou, X.; Smith, E. J.; Winterhalter, D.; McComas, D. J.; Skoug, R. M.; Goldstein, B. E.; Smith, C. W.

    2005-05-01

    Heliospheric current sheets (HCS) are well defined structures that separate the interplanetary magnetic fields with inverse polarities. Surrounded by heliospheric plasma sheets (HPS), the current sheets stretch throughout the heliosphere. Interesting questions that still remain unanswered include how the thickness of these structures will change along the distance? And what determines the thickness of these structures? To answer these fundamental questions, we have carried out a study of the HCS and HPS using recent Ulysses data near 5 AU. When the results were compared with earlier studies at 1 AU using ISEE-3 data, they were surprising and unexplained. Although the plasma sheet grew thicker, the embedded current sheet grew thinner! Using data under the same (or very similar) circumstances, we have extended the analysis in two ways. First, the same current-plasma sheets studied at 5 AU have been identified at 1 AU using ACE data. Second, data obtained while Ulysses was en-route to Jupiter near 3 AU have been analyzed. This three-point investigation reveals the thickness variation along the distance and enables the examination of the controller of this variation.

  10. Magnetic configuration of the distant plasma sheet - ISEE 3 observations

    Science.gov (United States)

    Slavin, J. A.; Smith, E. J.; Daly, P. W.; Sanderson, T. R.; Wenzel, K.-P.; Lepping, R. P.

    1987-01-01

    The influence of the IMF orientation and magnitude and substorm activity on the magnetic configuration of the central plasma sheet at 20-240 earth radii down the geomagnetic tail is investigated on the basis of ISEE-3 data. The results are presented graphically, and high-speed antisolar bulk flows threaded by southward magnetic fields are shown to be present in the distant plasma sheet after periods of substorm activity and southward IMF Bz. The effective dayside reconnection efficiency is estimated as 25 + or - 4 percent, in good agreement with theoretical models.

  11. Physics and Dynamics of Current Sheets in Pulsed Plasma Thrusters

    Science.gov (United States)

    2007-11-02

    pulsed plasma thruster. A simple experiment would involve measuring the impulse bit of a coaxial gas-fed pulsed plasma thruster operated in both positive...Princeton, NJ, 2002. [2] J. Marshal. Performance of a hydromagnetic plasma gun . The Physics of Fluids, 3(1):134–135, January-February 1960. [3] R.G. Jahn...Jahn and K.E. Clark. A large dielecteic vacuum facility. AIAA Jour- nal, 1966. [16] L.C. Burkhardt and R.H. Lovberg. Current sheet in a coaxial plasma

  12. Plasma-Jet Forming of Sheet Metal Shapes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Plasma-jet forming is a newly proposed flexible sheet metal forming process. A non-transferred arc plasma torch is used as a controllable heat source to produce internal stress in sheet metals, causing plastic deformation without the necessity of hard tooling. This method has potential for rapid prototyping of sheet metal parts by reducing development costs and lead times. A robotic system has been used to perform simple linear bends in several different alloys. In order to develop a controllable process and to improve the forming accuracy, the effects of various process parameters on the obtained shape changes and on the resulting structure and properties have been studied. The overall goal is to understand the roles of the forming parameters and their inter-relationship in optimizing the forming procedure-a high forming speed without damage to the material structure or properties.

  13. Plasma Sheet Actuator Driven by Repetitive Nanosecond Pulses with a Negative DC Component

    Institute of Scientific and Technical Information of China (English)

    宋慧敏; 张乔根; 李应红; 贾敏; 吴云; 梁华

    2012-01-01

    A type of electrical discharge called sliding discharge was developed to generate plasma aerodynamic actuation for flow control. A three-electrode plasma sheet actuator driven by repetitive nanosecond pulses with a negative DC component was used to generate sliding discharge, which can be called nanosecond-pulse sliding discharge. The phenomenology and behaviour of the plasma sheet actuator were investigated experimentally. Discharge morphology shows that the formation of nanosecond-pulse sliding discharge is dependent on the peak value of the repetitive nanosecond pulses and negative DC component applied on the plasma sheet actuator. Compared to dielectric barrier discharge (DBD), the extension of plasma in nanosecond-pulse sliding discharge is quasi-diffusive, stable, longer and more intensive. Test results of particle image velocimetry demonstrate that the negative DC component applied to a third electrode could significantly modify the topology of the flow induced by nanosecond-pulse DBD. Body force induced by the nanosecond-pulse sliding discharge can be approximately in the order of mN. Both the maximum velocity and the body force induced by sliding discharge increase significantly as compared to single DBD. Therefore, nanosecond-pulse sliding discharge is a preferable plasma aerodynamic actuation generation mode, which is very promising in the field of aerodynamics.

  14. Solar Energetic Particle Transport Near a Heliospheric Current Sheet

    Science.gov (United States)

    Battarbee, Markus; Dalla, Silvia; Marsh, Mike S.

    2017-02-01

    Solar energetic particles (SEPs), a major component of space weather, propagate through the interplanetary medium strongly guided by the interplanetary magnetic field (IMF). In this work, we analyze the implications that a flat Heliospheric Current Sheet (HCS) has on proton propagation from SEP release sites to the Earth. We simulate proton propagation by integrating fully 3D trajectories near an analytically defined flat current sheet, collecting comprehensive statistics into histograms, fluence maps, and virtual observer time profiles within an energy range of 1-800 MeV. We show that protons experience significant current sheet drift to distant longitudes, causing time profiles to exhibit multiple components, which are a potential source of confusing interpretations of observations. We find that variation of the current sheet thickness within a realistic parameter range has little effect on particle propagation. We show that the IMF configuration strongly affects the deceleration of protons. We show that in our model, the presence of a flat equatorial HCS in the inner heliosphere limits the crossing of protons into the opposite hemisphere.

  15. IMF dependence of energetic oxygen and hydrogen ion distributions in the near-Earth plasma sheet

    Science.gov (United States)

    Luo, Hao; Kronberg, Elena; Nykyri, Katariina; Daly, Patrick; Chen, Gengxiong; Du, Aimin; Ge, Yasong

    2017-04-01

    Energetic ion distributions in the near-Earth plasma sheet can provide important information for understanding the entry of ions into the magnetosphere, and their transportation, acceleration, and losses in the near-Earth region. In this study, 11 years of energetic proton and oxygen observations (> 100 keV) from Cluster/RAPID were used to statistically study the energetic ion distributions in the near-Earth region. The dawn-dusk asymmetries of the distributions in three different regions (dayside magnetosphere, near-Earth nightside plasma sheet, and tail plasma sheet) are examined in northern and southern hemispheres. The results show that the energetic ion distributions are influenced by the dawn-dusk IMF direction. The enhancement of intensity largely correlates with the location of the magnetic reconnection at the magnetopause and the consequent formation of a diamagnetic cavity in the same quadrant of the magnetosphere. The results imply that substorm-related processes in the magnetotail are not the only source of energetic ions in the dayside and the near-Earth plasma sheet. We propose that large-scale cusp diamagnetic cavities can be an additional source and can thus significantly affect the energetic ion population in the magnetosphere. We also believe that the influence of the dawn-dusk IMF direction should not be neglected in models of the particle population in the magnetosphere.

  16. Preparation of Sheet-like Polymer-Encapsulated Composite Particles by Seeded Polymerization from Sub-micrometer Sheets.

    Science.gov (United States)

    Huang, Ting; Yao, Kuncheng; Wu, Teng; Qiu, Dong

    2015-07-01

    Seeded polymerization has been widely used to fabricate polymer-encapsulated inorganic particles (IPs). The most frequently used seeds are spherical, whereas nonspherical particles are not well documented. Recently, sheet-like IPs have attracted much attention in the context of polymer composites. This article is therefore dedicated to understanding seeded polymerization from submicron sheets and focuses on the control of the overall morphology of the composite particles obtained. However, it was found that the composite particles only maintained the sheet-like morphology of the seeds at a low polymer content, whereas they became hamburger-like at a high polymer content owing to minimization of the interfacial energy. Interestingly, when cross-linked, the sheet-like morphology could be well preserved, even at a rather high polymer content. With the encapsulating polymer layer, the obtained sheet-like composite particles showed improved compatibility with the polymer matrix and could be well dispersed in polymer matrix when simply blended.

  17. Comparison of plasma sheet ion composition with the IMF and solar wind plasma

    Science.gov (United States)

    Lennartsson, W.

    Plasma sheet energetic ion data (0.1- to 16 keV/e) obtained by the Plasma Composition Experiment on ISEE-1 between 10 and 23 earth radii are compared with concurrent IMF and solar wind plasma data. The densities of H(+) and He(++) ions in the plasma sheet are found to be the highest, and the most nearly proportional to the solar wind density, when the IMF B(z) is not northward. The density of terrestrial O(+) ions increases strongly with increasing magnitude of the IMF, in apparent agreement with the notion that the IMF plays a fundamental role in the electric coupling between the solar wind and the ionosphere.

  18. On the plasma-based growth of ‘flowing’ graphene sheets at atmospheric pressure conditions

    Science.gov (United States)

    Tsyganov, D.; Bundaleska, N.; Tatarova, E.; Dias, A.; Henriques, J.; Rego, A.; Ferraria, A.; Abrashev, M. V.; Dias, F. M.; Luhrs, C. C.; Phillips, J.

    2016-02-01

    A theoretical and experimental study on atmospheric pressure microwave plasma-based assembly of free standing graphene sheets is presented. The synthesis method is based on introducing a carbon-containing precursor (C2H5OH) through a microwave (2.45 GHz) argon plasma environment, where decomposition of ethanol molecules takes place and carbon atoms and molecules are created and then converted into solid carbon nuclei in the ‘colder’ nucleation zones. A theoretical model previously developed has been further updated and refined to map the particle and thermal fluxes in the plasma reactor. Considering the nucleation process as a delicate interplay between thermodynamic and kinetic factors, the model is based on a set of non-linear differential equations describing plasma thermodynamics and chemical kinetics. The model predictions were validated by experimental results. Optical emission spectroscopy was applied to detect the plasma emission related to carbon species from the ‘hot’ plasma zone. Raman spectroscopy, scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS) techniques have been applied to analyze the synthesized nanostructures. The microstructural features of the solid carbon nuclei collected from the colder zones of plasma reactor vary according to their location. A part of the solid carbon was deposited on the discharge tube wall. The solid assembled from the main stream, which was gradually withdrawn from the hot plasma region in the outlet plasma stream directed to a filter, was composed by ‘flowing’ graphene sheets. The influence of additional hydrogen, Ar flow rate and microwave power on the concentration of obtained stable species and carbon-dicarbon was evaluated. The ratio of sp3/sp2 carbons in graphene sheets is presented. A correlation between changes in C2 and C number densities and sp3/sp2 ratio was found.

  19. 3-D Magnetospheric Field and Plasma Containing Thin Current Sheets

    Science.gov (United States)

    Zaharia, S.; Cheng, C. Z.; Maezawa, K.; Wing, S.

    2002-05-01

    In this study we present fully-3D self-consistent solutions of the magnetosphere by using observation-based plasma pressure distributions and computational boundary conditions based on the T96 magnetospheric field model. The pressure profiles we use are either taken directly from observations (GEOTAIL pressure data in the plasma sheet and DMSP ionospheric pressure) or empirical (Spence-Kivelson formula for pressure on the midnight equatorial line). The 3-D solutions involve solving 2 coupled elliptic equations in a flux coordinate systems, with the magnetic field expressed by two Euler potentials and using appropriate boundary conditions for both the closed- and open-field regions derived from the empirical field model. We look into how the self-consistent magnetic field and current structures change under different external conditions, and we discuss the appearance of thin cross-tail current sheets during disturbed magnetospheric times.

  20. Plasma sheet stretching accompanied by field aligned energetic ion fluxes observed by the MUADU instrument aboard TC-2

    Institute of Scientific and Technical Information of China (English)

    Lu Li; S.MCKENNA-LAWLOR; S.BARABASH; LIU ZhenXing; CAO JinBin; J.BALAZ; K.KUDELA; T.L.ZHANG; C.M.CARR

    2007-01-01

    The NUADU(NeUtral Atom Detector Unit)instrument aboard TC-2 recorded 4π solid angle images of charged particles(E>180 keV)spiraling around the magnetic field lines in the near-Earth plasma sheet (at~-7 RE,equatorial dawn-to-night side)during a geomagnetic storm(Dst=-219 nT)on August 24,2005.Energetic ion beam events characterized by symmetrical,ring-like,solid angle distributions around ambient magnetic field lines were observed during a 34-minute traversal of the plasma sheet by the TC-2 spacecraft.Also,observations during these multiple crossings of the plasma sheet were monitored by the magnetometer experiment(FGM)aboard the same spacecraft.During each crossing,a whistler-mode chorus enhancement was observed in the anisotropic area by the TC-2 low frequency electromagnetic wave detector(LFEW/TC-2)at a frequency just above that of the local lower hybrid wave.A comparison of the ion pitch angle distribution(PAD)map with the ambient magnetic field shows that an enhancement in the field aligned energetic ion flux was accompanied by tailward stretching of the magnetic field lines in the plasma sheet.In contrast,the perpendicular ion-flux enhancement was accompanied by a signature indicating the corresponding shrinkage of the magnetic field lines in the plasma sheet.Since both parallel ion-flux and perpendicular ion-flux enhancements occurred intermittently,the data were interpreted to imply a dynamical,oscillatory process of the magnetic field line(stretching and shrinking)in the near-Earth plasma sheet,which might have acted to help establish an interaction region in this area which would support continuous aurora-substorm triggering during the ongoing magnetic storm.The whistler-mode chorus may have been produced due to ion gyro-resonance during particle pitch angle diffusion after the plasma sheet compression.

  1. Singular Sheet Etching of Graphene with Oxygen Plasma

    Institute of Scientific and Technical Information of China (English)

    Haider Al-Mumen; Fubo Rao; Wen Li; Lixin Dong

    2014-01-01

    This paper reports a simple and controllable post-synthesis method for engineering the number of graphene layers based on oxygen plasma etching. Singular sheet etching (SSE) of graphene was achieved with the optimum process duration of 38 seconds. As a demonstration of this SSE process, monolayer graphene films were produced from bilayer graphenes. Experimental investigations verified that the oxygen plasma etching removes a single layer graphene sheet in an anisotropic fashion rather than anisotropic mode. In addition, etching via the oxygen plasma at the ground electrodes introduced fewer defects to the bottom graphene layer compared with the conventional oxygen reactive ion etching using the powered electrodes. Such defects can further be reduced with an effective annealing treatment in an argon environment at 900-1000◦C. These results demonstrate that our developed SSE method has enabled a microelectronics manufacturing compatible way for single sheet precision subtraction of graphene layers and a potential technique for producing large size graphenes with high yield from multilayer graphite materials.

  2. Analysis of radiation performances of plasma sheet antenna

    Science.gov (United States)

    Yin, Bo; Zhang, Zu-Fan; Wang, Ping

    2015-12-01

    A novel concept of plasma sheet antennas is presented in this paper, and the radiation performances of plasma sheet antennas are investigated in detail. Firstly, a model of planar plasma antenna (PPA) fed by a microstrip line is developed, and its reflection coefficient is computed by the JE convolution finite-difference time-domain method and compared with that of the metallic patch antenna. It is found that the design of PPA can learn from the theory of the metallic patch antenna, and the impedance matching and reconstruction of resonant frequency can be expediently realized by adjusting the parameters of plasma. Then the PPA is mounted on a metallic cylindrical surface, and the reflection coefficient of the conformal plasma antenna (CPA) is also computed. At the same time, the influence of conformal cylinder radius on the reflection coefficient is also analyzed. Finally, the radiation pattern of a CPA is given, the results show that the pattern agrees well with the one of PPA in the main radiation direction, but its side lobe level has deteriorated significantly.

  3. On the 3-dimensional structure of plasmoids. [in near-earth plasma sheets

    Science.gov (United States)

    Hughes, W. J.; Sibeck, D. G.

    1987-01-01

    The hypothesis that the IMF penetrates plasmoids causing them to be three- rather than two-dimensional is tested by comparing observations of By within plasmoids and related tail structures to upstream IMF By data. The magnetic topologies that result from the mergings of closed plasma sheet flux tubes and open tail lobe flux tubes at a near-earth neutral line, and merging near the tail flanks are described and studied. The particle signals and isotropic electron distributions are examined. It is observed that the IMF By penetrates plasmoids and that their structure is three-dimensional. In the three-dimensional model of plasmoids the reconnected plasma sheet field lines form a magnetic flux-ropelike structure. The three-dimensional model is utilized to analyze stagnant, slowly moving and earthward moving structures.

  4. Thin current sheets caused by plasma flow gradients in space plasma

    Science.gov (United States)

    Nickeler, D.; Wiegelmann, T.

    2011-12-01

    To understand complex space plasma systems like the solar wind-magnetosphere coupling, we need to have a good knowledge of the slowly evolving equilibrium state. The slow change of external constraints on the system (for example boundary conditions or other external parameters) lead in many cases to the formation of current sheets. These current sheets can trigger micro-instabilities, which cause resistivity on fluid scales. Consequently resistive instabilities like magnetic reconnection can occur and the systems evolves dynamically. Therefore such a picture of quasi-magneto-hydro-static changes can explain the quasy-static phase of many space plasma before an eruption occurs. Within this work we extend the theory by the inclusion of a nonlinear stationary plasma flows. Our analysis shows that stationary plasma flows with strong flow gradients (for example the solar wind magnetosphere coupling) can be responsible for the existence or generation of current sheets.

  5. Survey of Galileo Plasma Observations in Jupiter's Plasma Sheet

    Science.gov (United States)

    Bagenal, Fran; Wilson, Robert J.; Siler, Scott; Paterson, William R.; Kurth, William S.

    2016-01-01

    The plasma science (PLS) Instrument on the Galileo spacecraft (orbiting Jupiter from December 1995 to September 2003) measured properties of the ions that were trapped in the magnetic field. The PLS data provide a survey of the plasma properties between approx. 5 and 30 Jupiter radii [R(sub J)] in the equatorial region. We present plasma properties derived via two analysis methods: numerical moments and forward modeling. We find that the density decreases with radial distance by nearly 5 orders of magnitude from approx. 2 to 3000 cm(exp.-3) at 6R(sub j) to approx. 0.05cm(sub -3) at 30 R(sub j). The density profile did not show major changes from orbit to orbit, suggesting that the plasma production and transport remained constant within about a factor of 2. The radial profile of ion temperature increased with distance which implied that contrary to the concept of adiabatic cooling on expansion, the plasma heats up as it expands out from Io's orbit (where TI is approx.60-80 eV) at approx. 6R(sub j) to a few keV at 30R(sub j).There does not seem to be a long-term, systematic variation in ion temperature with either local time or longitude. This latter finding differs from earlier analysis of Galileo PLS data from a selection of orbits. Further examination of all data from all Galileo orbits suggests that System Ill variations are transitory on timescales of weeks, consistent with the modeling of Cassini Ultraviolet Imaging Spectrograph observations. The plasma flow is dominated by azimuthal flow that is between 80% and 100% of corotation out to 25 R(sub j).

  6. Particles formation in an expanding plasma

    Energy Technology Data Exchange (ETDEWEB)

    Lescoute, E.; Hallo, L.; Chimier, B.; Tikhonchuk, V.T.; Stenz, C. [Bordeaux-1 Univ., CELIA, CNRS-CEA, 33 - Talence (France); Hebert, D.; Chevalier, J.M.; Rullier, J.L.; Palmier, S. [CEA Centre d' Etudes Scientifiques et Techniques d' Aquitaine, 33 - Le Barp (France)

    2009-08-15

    Interaction of a laser beam with a target generates a high velocity expanding plasma plume, solid debris and liquid nano- and micro-particles. They are produced from plasma recombination and vapor condensation and can be deposited on optical elements located nearby the target. Two distinct kinds of particles were observed depending on the temperature achieved in the plasma plume: large micrometer-size fragments for temperatures lower than the critical temperature, and very small nanometer-size particles for higher temperatures. The paper presents experimental observations of fragments and nano-particles in plasma plumes and a comparison with models. A good agreement has been found for nano-particle sizes and distributions. This simple modeling can also be used for nuclei production in the nanosecond time scale. Our estimates show that particle size can be correlated to laser wavelength and fluences.

  7. Monitoring particle growth in deposition plasmas

    Science.gov (United States)

    Schlebrowski, T.; Bahre, H.; Böke, M.; Winter, J.

    2013-12-01

    Plasma-enhanced chemical vapor deposition methods are frequently used to deposit barrier layers, e.g. on polymers for food packaging. These plasmas may suffer from particle (dust) formation. We report on a flexible monitoring system for dust. It is based on scanning a 3D plasma volume for particles by laser light scattering. The lower size limit of particles detected in the presented system is 20 nm. We report on existence diagrams for obtaining dust free or dust loaded capacitively or inductively coupled rf-plasmas in C2H2 depending on pressure, flow and rf-power. We further present growth rates for dust in these plasmas and show that monodisperse particles are only obtained during the first growth cycle.

  8. Effects of auroral potential drops on plasma sheet dynamics

    Science.gov (United States)

    Xi, Sheng; Lotko, William; Zhang, Binzheng; Wiltberger, Michael; Lyon, John

    2016-11-01

    The reaction of the magnetosphere-ionosphere system to dynamic auroral potential drops is investigated using the Lyon-Fedder-Mobarry global model including, for the first time in a global simulation, the dissipative load of field-aligned potential drops in the low-altitude boundary condition. This extra load reduces the field-aligned current (j||) supplied by nightside reconnection dynamos. The system adapts by forcing the nightside X line closer to Earth, with a corresponding reduction in current lensing (j||/B = constant) at the ionosphere and additional contraction of the plasma sheet during substorm recovery and steady magnetospheric convection. For steady and moderate solar wind driving and with constant ionospheric conductance, the cross polar cap potential and hemispheric field-aligned current are lower by approximately the ratio of the peak field-aligned potential drop to the cross polar cap potential (10-15%) when potential drops are included. Hemispheric ionospheric Joule dissipation is less by 8%, while the area-integrated, average work done on the fluid by the reconnecting magnetotail field increases by 50% within |y| < 8 RE. Effects on the nightside plasma sheet include (1) an average X line 4 RE closer to Earth; (2) a 12% higher mean reconnection rate; and (3) dawn-dusk asymmetry in reconnection with a 17% higher rate in the premidnight sector.

  9. Cluster multi-point observations of the magnetotail plasma sheet

    Science.gov (United States)

    Henderson, Paul David

    This thesis presents observations of the terrestrial magnetotail plasma sheet made by the European Space Agency Cluster mission. The Cluster mission is composed of four identical spacecraft, the first such multi-spacecraft mission, and enables, for the first time, the disambiguation of time versus space phenomena. Using the data from 2003, when the spacecraft were at their smallest average separation to date, many small-scale processes, both microphysical and macrophysical, are investigated. In the first study presented, two small flux ropes, a possible signature of multiple X-line reconnection, are investigated. By the development and utilisation of various multi-spacecraft methods, the currents and magnetic forces internal and external to the flux ropes, as well as the internal structure of the flux ropes, are investigated. In addition, a theory of their early evolution is suggested. In the second study presented, various terms of the generalised Ohm's law for a plasma are determined, including, for the first time, the divergence of the full electron pressure tensor, during the passage past the spacecraft of an active reconnection X-line. It is found that the electric field contribution from the divergence of the electron pressure tensor is anti-correlated with the contribution from the Hall term in the direction normal to the neutral sheet. In addition, further signatures of reconnection are quantified, such as parallel electric field generation and Hall quadrupolar magnetic field and current systems. In the final study presented, the anti-correlation between the divergence of the electron pressure tensor and Hall terms is investigated further. It is found that the anti-correlation is general, appearing in the direction normal to the neutral sheet because of a cross tail current. In a simple magnetohydrostatic treatment, a force balance argument leads to the conclusion that the gradient of the anti-correlation is a function of the ratio of the electron to ion

  10. Casimir effects for a flat plasma sheet: I. Energies

    Energy Technology Data Exchange (ETDEWEB)

    Barton, G [Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom)

    2005-04-01

    We study a fluid model of an infinitesimally thin plasma sheet occupying the xy plane, loosely imitating a single base plane from graphite. In terms of the fluid charge e/a{sup 2} and mass m/a{sup 2} per unit area, the crucial parameters are q nsce 2{pi}e{sup 2}/mc{sup 2}a{sup 2}, a Debye-type cutoff K{identical_to}{radical}(4{pi})/a on surface-parallel normal-mode wavenumbers k, and X nsce K/q. The cohesive energy {beta} per unit area is determined from the zero-point energies of the exact normal modes of the plasma coupled to the Maxwell field, namely TE and TM photon modes, plus bound modes decaying exponentially with vertical bar zvertical bar. Odd-parity modes (with E{sub x,y}(z = 0) = 0) are unaffected by the sheet except for their overall phases, and are irrelevant to {beta}, although the following paper shows that they are essential to the fields (e.g. to their vacuum expectation values), and to the stresses on the sheet. Realistically one has X >> 1, the result {beta} {approx} {Dirac_h}cq{sup 1/2}K{sup 5/2} is nonrelativistic, and it comes from the surface modes. By contrast, X << 1 (nearing the limit of perfect reflection) would entail {beta} {approx} -{Dirac_h}cqK{sup 2}log(1/X): contrary to folklore, the surface energy of perfect reflectors is divergent rather than zero. An appendix spells out the relation, for given k, between bound modes and photon phase-shifts. It is very different from Levinson's theorem for 1D potential theory: cursory analogies between TM and potential scattering are apt to mislead.

  11. Investigation of plasma particle interactions with variable particle sizes

    Science.gov (United States)

    Dropmann, Michael; Laufer, Rene; Herdrich, Georg; Matthews, Lorin; Hyde, Truell

    2015-11-01

    In dusty plasmas, the dust particles are subjected to many forces of different origins. Both the gas and plasma directly affect the dust particles through electric fields, neutral drag, ion drag and thermophoretic forces, while the particles themselves interact with one another through a screened coulomb potential, which can be influenced by flowing ions. Recently, micron sized particles have been used as probes to analyze the electric fields in the plasma directly. A proper analysis of the resulting data requires a full understanding of the manner in which these forces couple to the dust particles. In most cases each of the forces exhibit unique characteristics, many of which are partially dependent on the particle size. In this study, five different particle sizes are used to investigate the forces resident in the sheath above the lower electrode of a GEC RF reference cell. The particles are tracked using a high-speed camera, yielding two-dimensional force maps allowing the force on the particles to be described as a polynomial series. It will be shown that the data collected can be analyzed to reveal information about the origins of the various forces. Support from the NSF and the DOE (award numbers PHY-1262031 and PHY-1414523) is gratefully acknowledged.

  12. Thin current sheets caused by plasma flow gradients in space and astrophysical plasma

    Directory of Open Access Journals (Sweden)

    D. H. Nickeler

    2010-08-01

    Full Text Available Strong gradients in plasma flows play a major role in space and astrophysical plasmas. A typical situation is that a static plasma equilibrium is surrounded by a plasma flow, which can lead to strong plasma flow gradients at the separatrices between field lines with different magnetic topologies, e.g., planetary magnetospheres, helmet streamers in the solar corona, or at the boundary between the heliosphere and interstellar medium. Within this work we make a first step to understand the influence of these flows towards the occurrence of current sheets in a stationary state situation. We concentrate here on incompressible plasma flows and 2-D equilibria, which allow us to find analytic solutions of the stationary magnetohydrodynamics equations (SMHD. First we solve the magnetohydrostatic (MHS equations with the help of a Grad-Shafranov equation and then we transform these static equilibria into a stationary state with plasma flow. We are in particular interested to study SMHD-equilibria with strong plasma flow gradients perpendicular to separatrices. We find that induced thin current sheets occur naturally in such situations. The strength of the induced currents depend on the Alfvén Mach number and its gradient, and on the magnetic field.

  13. Particles and plasmas in the earth's magnetotail at 60 earth radii

    Science.gov (United States)

    Anderson, K. A.; Chase, L. M.; Lin, R. P.; Mcguire, R. E.; Mccoy, J. E.

    1974-01-01

    The main purpose of this article is to describe the plasma and particle populations in the magnetotail near 60 earth radii geocentric distance. Both the plasma sheet and the high-latitude portions of the magnetotail are discussed. Electron and proton spectra at energies above about 20 keV and electron spectra down to 0.5 keV have been obtained. Another topic of importance is the comparison of the deep magnetotail plasma sheet with the Vela satellite measurements at about 20 earth radii geocentric distance.

  14. QUANTITATIVE FLOW-ANALYSIS AROUND AQUATIC ANIMALS USING LASER SHEET PARTICLE IMAGE VELOCIMETRY

    NARCIS (Netherlands)

    STAMHUIS, EJ; VIDELER, JJ

    1995-01-01

    Two alternative particle image velocimetry (PIV) methods have been developed, applying laser light sheet illumination of particle-seeded flows around marine organisms, Successive video images, recorded perpendicular to a light sheet parallel to the main stream, were digitized and processed to map th

  15. QUANTITATIVE FLOW-ANALYSIS AROUND AQUATIC ANIMALS USING LASER SHEET PARTICLE IMAGE VELOCIMETRY

    NARCIS (Netherlands)

    STAMHUIS, EJ; VIDELER, JJ

    Two alternative particle image velocimetry (PIV) methods have been developed, applying laser light sheet illumination of particle-seeded flows around marine organisms, Successive video images, recorded perpendicular to a light sheet parallel to the main stream, were digitized and processed to map

  16. Explosive Particle Dispersion in Plasma Turbulence

    CERN Document Server

    Servidio, S; Matthaeus, W H; Burgess, D; Carbone, V; Veltri, P

    2016-01-01

    Particle dynamics are investigated in plasma turbulence, using self-consistent kinetic simulations, in two dimensions. In steady state, the trajectories of single protons and proton-pairs are studied, at different values of plasma "beta" (ratio between kinetic and magnetic pressure). For single-particle displacements, results are consistent with fluids and magnetic field line dynamics, where particles undergo normal diffusion for very long times, with higher "beta" being more diffusive. In an intermediate time range, with separations lying in the inertial range, particles experience an explosive dispersion in time, consistent with the Richardson prediction. These results, obtained for the first time with a self-consistent kinetic model, are relevant for astrophysical and laboratory plasmas, where turbulence is crucial for heating, mixing and acceleration processes.

  17. ISEE 3 observations during a plasma sheet encounter at 140 earth radii - Evidence for enhancement of reconnection at the distant neutral line

    Science.gov (United States)

    Scholer, M.; Terasawa, T.; Baker, D. N.; Zwickl, R. D.; Gloeckler, G.; Hovestadt, D.; Smith, E. J.; Tsurutani, B. T.

    1986-01-01

    A plasma sheet encounter of the ISEE-3 spacecraft in the distant tail at 140 earth radii on March 20, 1983 is studied using magnetic field, energetic particle, and plasma electron data sets. The H-component magnetograms from auroral magnetometer stations, intensity-time profiles, high resolution magnetic field measurements, and electron and proton angular distributions are analyzed. The dynamics of the plasma sheet displayed by the strong tailward and earthward directed ion beams, large northward and southward magnetic fields excursions, and short tailward and earthward plasma flows are described.

  18. Responses of properties in the plasma sheet and at the geosynchronous orbit to interplanetary shock

    Institute of Scientific and Technical Information of China (English)

    YAO Li; LIU ZhenXing; ZUO PingBing; ZHANG LingQian; DUAN SuPing

    2009-01-01

    On July 22,2004,the WIND spacecraft detected a typical interplanetary shock. There was sustaining weak southward magnetic field in the preshock region and the southward field was suddenly enhanced across the shock front (i.e.,southward turning). When the shock impinged on the magnetosphere,the magnetospheric plasma convection was abruptly enhanced in the central plasma sheet,which was directly observed by both the TC-1 and Cluster spacecraft located in different regions. Simultaneously,the Cluster spacecraft observed that the dawn-to-dusk electric field was abruptly enhanced. The variations of the magnetic field observed by TC-1,Cluster,GOES-10 and GOES-12 that were distributed in different regions in the plasma sheet and at the geosynchronous orbit are obviously distinct. TC-1 observations showed that the magnetic intensity kept almost unchanged and the elevation angle decreased,but the Cluster spacecraft,which was also in the plasma sheet and was further from the equator,observed that the magnetic field was obviously enhanced. Simultaneously,GOES-12 located near the midnight observed that the magnetic intensity sharply increased and the elevation angle decreased,but GOES-10 located in the dawn side observed that the magnetic field was merely compressed with its three components all sharply increasing. Furthermore,the energetic proton and electron fluxes at nearly all channels observed by five LANL satellites located at different magnetic local times (MLTs) all showed impulsive enhancements due to the compression of the shock. The responses of the energetic particles were much evident on the dayside than those on the nightside. Especially the responses near the midnight were rather weak. In this paper,the possible reasonable physical explanation to above observations is also discussed. All the shock-induced responses are the joint effects of the solar wind dynamic pressure pulse and the magnetic field southward turning.

  19. Experimental investigation of a 1 kA/cm² sheet beam plasma cathode electron gun.

    Science.gov (United States)

    Kumar, Niraj; Pal, Udit Narayan; Pal, Dharmendra Kumar; Prajesh, Rahul; Prakash, Ram

    2015-01-01

    In this paper, a cold cathode based sheet-beam plasma cathode electron gun is reported with achieved sheet-beam current density ∼1 kA/cm(2) from pseudospark based argon plasma for pulse length of ∼200 ns in a single shot experiment. For the qualitative assessment of the sheet-beam, an arrangement of three isolated metallic-sheets is proposed. The actual shape and size of the sheet-electron-beam are obtained through a non-conventional method by proposing a dielectric charging technique and scanning electron microscope based imaging. As distinct from the earlier developed sheet beam sources, the generated sheet-beam has been propagated more than 190 mm distance in a drift space region maintaining sheet structure without assistance of any external magnetic field.

  20. Nongyrotropic particle distributions in space plasmas

    Directory of Open Access Journals (Sweden)

    U. Motschmann

    Full Text Available In nonstationary, strong inhomogeneous or open plasmas particle orbits are rather complicated. If the nonstationary time scale is smaller than the gyration period, if the inhomogeneity scale is smaller than the gyration radius, i.e. at magnetic plasma boundaries, or if the plasma has sources and sinks in phase space, then nongyrotropic distribution functions occur. The stability of such plasma configurations is studied in the framework of linear dispersion theory. In an open plasma nongyrotropy drives unstable waves parallel and perpendicular to the background magnetic field, whereas in the gyrotropic limit the plasma is stable. In nonstationary plasmas nongyrotropy drives perpendicular unstable waves only. Temporal modulation couples a seed mode with its side lobes and thus it renders unstable wave growth more difficult. As an example of an inhomogeneous plasma a magnetic halfspace is discussed. In a layer with thickness of the thermal proton gyroradius a nongyrotropic distribution is formed which may excite unstable parallel and perpendicular propagating waves.

    Key words. Interplanetary physics (plasma waves and turbulence · Ionosphere (plasma waves and instabilities · Magnetospheric physics (plasma waves and instabilities

  1. Current sheets with inhomogeneous plasma temperature: Effects of polarization electric field and 2D solutions

    Energy Technology Data Exchange (ETDEWEB)

    Catapano, F., E-mail: menacata3@gmail.com; Zimbardo, G. [Dipartimento di Fisica, Università della Calabria, Rende, Cosenza (Italy); Artemyev, A. V., E-mail: ante0226@gmail.com; Vasko, I. Y. [Space Research Institute, RAS, Moscow (Russian Federation)

    2015-09-15

    We develop current sheet models which allow to regulate the level of plasma temperature and density inhomogeneities across the sheet. These models generalize the classical Harris model via including two current-carrying plasma populations with different temperature and the background plasma not contributing to the current density. The parameters of these plasma populations allow regulating contributions of plasma density and temperature to the pressure balance. A brief comparison with spacecraft observations demonstrates the model applicability for describing the Earth magnetotail current sheet. We also develop a two dimensional (2D) generalization of the proposed model. The interesting effect found for 2D models is the nonmonotonous profile (along the current sheet) of the magnetic field component perpendicular to the current sheet. Possible applications of the model are discussed.

  2. Spatial variation of eddy-diffusion coefficients in the turbulent plasma sheet during substorms

    Directory of Open Access Journals (Sweden)

    M. Stepanova

    2009-04-01

    Full Text Available Study of the plasma turbulence in the central plasma sheet was performed using the Interball-Tail satellite data. Fluctuations of the plasma bulk velocity in the plasma sheet were deduced from the measurements taken by the Corall instrument for different levels of geomagnetic activity and different locations inside the plasma sheet. The events that satisfied the following criteria were selected for analysis: number density 0.1–10 cm−3, ion temperature T≥0.3 keV, and average bulk velocity ≤100 km/s. It was found that the plasma sheet flow generally appears to be strongly turbulent, i.e. is dominated by fluctuations that are unpredictable. Corresponding eddy-diffusion coefficients in Y- and Z-direction in the GSM coordinate system were derived using the autocorrelation time and rms velocity. Statistical studies of variation of the eddy-diffusion coefficients with the location inside the plasma sheet showed a significant increase in these coefficients in the tailward direction. During substorms this dependence shows strong increase of eddy-diffusion in the central part of the plasma sheet at the distances of 10–30 Earth's radii. This effect is much stronger for Y-components of the eddy-diffusion coefficient, which could be related to the geometry of the plasma sheet, allowing more room for development of eddies in this direction.

  3. A statistical study on the correlations between plasma sheet and solar wind based on DSP explorations

    Directory of Open Access Journals (Sweden)

    G. Q. Yan

    2005-11-01

    Full Text Available By using the data of two spacecraft, TC-1 and ACE (Advanced Composition Explorer, a statistical study on the correlations between plasma sheet and solar wind has been carried out. The results obtained show that the plasma sheet at geocentric distances of about 9~13.4 Re has an apparent driving relationship with the solar wind. It is found that (1 there is a positive correlation between the duskward component of the interplanetary magnetic field (IMF and the duskward component of the geomagnetic field in the plasma sheet, with a proportionality constant of about 1.09. It indicates that the duskward component of the IMF can effectively penetrate into the near-Earth plasma sheet, and can be amplified by sunward convection in the corresponding region at geocentric distances of about 9~13.4 Re; (2 the increase in the density or the dynamic pressure of the solar wind will generally lead to the increase in the density of the plasma sheet; (3 the ion thermal pressure in the near-Earth plasma sheet is significantly controlled by the dynamic pressure of solar wind; (4 under the northward IMF condition, the ion temperature and ion thermal pressure in the plasma sheet decrease as the solar wind speed increases. This feature indicates that plasmas in the near-Earth plasma sheet can come from the magnetosheath through the LLBL. Northward IMF is one important condition for the transport of the cold plasmas of the magnetosheath into the plasma sheet through the LLBL, and fast solar wind will enhance such a transport process.

  4. Modification of Plasma Solitons by Resonant Particles

    DEFF Research Database (Denmark)

    Karpman, Vladimir; Lynov, Jens-Peter; Michelsen, Poul;

    1980-01-01

    A consistent theory of plasma soliton interaction with resonant particles is developed. A simple derivation of a perturbed Korteweg–de Vries equation with the interaction term is presented. It is shown how the known limit cases (such as Ott–Sudan’s, etc.) can be derived from the general equations...... Korteweg–de Vries equation. Laboratory measurements carried out in a strongly magnetized, plasma‐filled waveguide and results from particle simulation are interpreted in terms of the analytical results....

  5. Interaction of plasma vortices with resonant particles

    DEFF Research Database (Denmark)

    Jovanovic, D.; Pécseli, Hans; Juul Rasmussen, J.

    1990-01-01

    Kinetic effects associated with the electron motion along magnetic field lines in low‐beta plasmas are studied. Using the gyrokinetic description of electrons, a kinetic analog of the reduced magnetohydrodynamic equations is derived, and it is shown that in the strongly nonlinear regime they poss......Kinetic effects associated with the electron motion along magnetic field lines in low‐beta plasmas are studied. Using the gyrokinetic description of electrons, a kinetic analog of the reduced magnetohydrodynamic equations is derived, and it is shown that in the strongly nonlinear regime...... particles. The evolution equations indicate the possibility of excitation of plasma vortices by electron beams....

  6. A study of the formation and dynamics of the Earth's plasma sheet using ion composition data

    Science.gov (United States)

    Lennartsson, O. W.

    1994-01-01

    Over two years of data from the Lockheed Plasma Composition Experiment on the ISEE 1 spacecraft, covering ion energies between 100 eV/e and about 16 keV/e, have been analyzed in an attempt to extract new information about three geophysical issues: (1) solar wind penetration of the Earth's magnetic tail; (2) relationship between plasma sheet and tail lobe ion composition; and (3) possible effects of heavy terrestrial ions on plasma sheet stability.

  7. Particle growth in hydrogen-methane plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, T. [Centre for Interdisciplinary Plasma Science, Max-Planck Institute for extraterrestrial Physics, Giessenbachstr. 1, D-85741 Garching (Germany); Jacob, W. [Centre for Interdisciplinary Plasma Science, Max-Planck Institute for Plasma Physics, Boltzmanstr. 2, D-85748 Garching (Germany); Thomas, H. [Centre for Interdisciplinary Plasma Science, Max-Planck Institute for extraterrestrial Physics, Giessenbachstr. 1, D-85741 Garching (Germany); Morfill, G. [Centre for Interdisciplinary Plasma Science, Max-Planck Institute for extraterrestrial Physics, Giessenbachstr. 1, D-85741 Garching (Germany); Abe, T. [Department of Electronic Device and Materials, Tohoku Institute of Technology, 35-1, Kasumi-cho, Yagiyama, Taihaku-ku, Sendai 982-8577 (Japan); Watanabe, Y. [Graduate School of Information Science and Electrical Engineering, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan); Sato, N. [Centre for Interdisciplinary Plasma Science, Max-Planck Institute for extraterrestrial Physics, Giessenbachstr. 1, D-85741 Garching (Germany); Professor Emeritus, Tohoku University, 05, Aramaki-Aza-Aoba, Aoba-ku, Sendai 980-8579 (Japan)

    2006-05-26

    Particle growth and the behavior of particle clouds in hydrogen-methane capacitively coupled rf plasmas are investigated. At room temperature, most for different wall temperatures and gas compositions of these particles are due to flakes of layers delaminated from the electrode surfaces. Heating of the electrodes up to 800 K and dilution by hydrogen (up to H{sub 2}:CH{sub 4} = 20:1) suppresses the production of the particles from the electrode surfaces. The electron temperature in the particle levitation region is controlled by introducing an additional electrode made from a grid (= gridded electrode) in between the levitation electrode and the driven electrode. If we introduce diamond seed particles ({approx} 2.8 {mu}m in diameter) into the plasma with the gridded electrode in place, we observe nucleation of new grains ({approx} 100 nm) on the surfaces of the diamond particles. On the other hand, without the gridded electrode, we do not observe nucleation but growth of amorphous carbon films on them.

  8. Major minority: energetic particles in fusion plasmas

    Science.gov (United States)

    Breizman, B. N.; Sharapov, S. E.

    2011-05-01

    This paper describes advances made in the field of energetic-particle physics since the topical review of Alfvén eigenmode observations in toroidal plasmas (Wong 1999 Plasma Phys. Control. Fusion 41 R1-R56). The development of plasma confinement scenarios with reversed magnetic shear and significant population of energetic particles, and the development of novel energetic-particle diagnostics were the main milestones in the past decade, and these are the main experimental subjects of this review. The theory of Alfvén cascade eigenmodes in reversed-shear tokamaks and its use in magnetohydrodynamic spectroscopy are presented. Based on experimental observations and nonlinear theory of energetic-particle instabilities in the near-threshold regime, the frequency-sweeping events for spontaneously formed phase-space holes and clumps and the evolution of the fishbone oscillations are described. The multi-mode scenarios of enhanced particle transport are discussed and a brief summary is given of several engaging research topics that are beyond the authors' direct involvement.

  9. Studies of Particle Wake Potentials in Plasmas

    Science.gov (United States)

    Ellis, Ian; Graziani, Frank; Glosli, James; Strozzi, David; Surh, Michael; Richards, David; Decyk, Viktor; Mori, Warren

    2011-10-01

    Fast Ignition studies require a detailed understanding of electron scattering, stopping, and energy deposition in plasmas with variable values for the number of particles within a Debye sphere. Presently there is disagreement in the literature concerning the proper description of these processes. Developing and validating proper descriptions requires studying the processes using first-principle electrostatic simulations and possibly including magnetic fields. We are using the particle-particle particle-mesh (PPPM) code ddcMD and the particle-in-cell (PIC) code BEPS to perform these simulations. As a starting point in our study, we examine the wake of a particle passing through a plasma in 3D electrostatic simulations performed with ddcMD and with BEPS using various cell sizes. In this poster, we compare the wakes we observe in these simulations with each other and predictions from Vlasov theory. Prepared by LLNL under Contract DE-AC52-07NA27344 and by UCLA under Grant DE-FG52-09NA29552.

  10. Plasma and energetic particles in the magnetotail at 60 earth radii

    Science.gov (United States)

    Chase, L. M.; Mcguire, R. E.; Lin, R. P.; Anderson, K. A.; Mccoy, J. E.; Hones, E. W.

    1974-01-01

    Particle measurements made by the lunar-orbiting Apollo subsatellites have shown that electron energy spectra in the range 0.55-320 keV in the high-latitude magnetotail often fit a power law with an exponent of -3 and a flux at .5 keV of 200,000 to 700,000 el/sq cm s sr keV. In the magnetosheath, electron energy spectra are similar to the high-latitude magnetotail spectra. In the plasma sheet, electron energy spectra often fit the high-energy tail of a Maxwellian distribution with Eo of about 200-500 eV. During times of substorms a number of cases where the plasma sheet appears to thin at onset have been observed. In addition, cases of plasma sheet expansion at onset have also been observed.

  11. Forensic analysis of tempered sheet glass by particle induced X-ray emission (PIXE)

    Energy Technology Data Exchange (ETDEWEB)

    Jisonna, L.J. [Department of Chemistry and Department of Physics, Hope College, Holland, MI 49422-9000 (United States); DeYoung, P.A., E-mail: deyoung@hope.ed [Department of Chemistry and Department of Physics, Hope College, Holland, MI 49422-9000 (United States); Ferens, J.; Hall, C.; Lunderberg, J.M.; Mears, P. [Department of Chemistry and Department of Physics, Hope College, Holland, MI 49422-9000 (United States); Padilla, D. [Department of Physics, San Diego State University, San Diego, CA 92182-1233 (United States); Peaslee, G.F. [Department of Chemistry and Department of Physics, Hope College, Holland, MI 49422-9000 (United States); Sampson, R. [Department of Physics, Columbia University, New York, NY 10027 (United States)

    2011-05-15

    Highlights: {yields} PIXE was found to give the same results for trace elements in glass as ICP. {yields} PIXE can non-destructively determine trace element concentrations in auto glass. {yields} Measured Ca, Fe, Ti, Mn, and Sr in auto glass with PIXE. -- Abstract: The elemental concentrations of five trace elements in tempered sheet glass fragments were determined using particle-induced X-ray emission (PIXE) spectrometry. The trace element concentrations for calcium, iron, manganese, strontium, and titanium are compared to those obtained by inductively-coupled plasma-atomic emission spectrometry (ICP-AES) following complete digestion by hydrofluoric acid. For these five elements, the absolute concentrations obtained by both methods are shown to agree well over a wide range of concentrations. The limits of detection for trace elements are typically lower for the ICP-AES method. However, we show that the concentrations of these five elements can be accurately measured by the PIXE method. Since PIXE is an entirely non-destructive method, there exists a niche for this technique to be used as a complement to the more sensitive ICP-AES technique in the forensic analysis of sheet glass.

  12. Cluster view of the plasma sheet boundary layer and bursty bulk flow connection

    Directory of Open Access Journals (Sweden)

    O. W. Lennartsson

    2009-04-01

    separations. Altogether, the Cluster observations described here mesh rather well with theories about so called plasma sheet "bubbles," i.e. earthward drifting closed magnetic flux tubes with reduced particle pressure and enhanced magnetic field strength at their apex. It is argued that such bubbles may be initiated by localized diamagnetic instabilities.

  13. Extraordinary Matter: Visualizing Space Plasmas and Particles

    Science.gov (United States)

    Barbier, S. B.; Bartolone, L.; Christian, E.; Thieman, J.; Eastman, T.; Lewis, E.

    2011-09-01

    Atoms and sub-atomic particles play a crucial role in the dynamics of our universe, but these particles and the space plasmas comprised of them are often overlooked in popular scientific and educational resources. Although the concepts are pertinent to a wide range of topics, even the most basic particle and plasma physics principles are generally unfamiliar to non-scientists. Educators and public communicators need assistance in explaining these concepts that cannot be easily demonstrated in the everyday world. Active visuals are a highly effective aid to understanding, but resources of this type are currently few in number and difficult to find, and most do not provide suitable context for audience comprehension. To address this need, our team is developing an online multimedia reference library of animations, visualizations, interactivities, and videos resources - Extraordinary Matter: Visualizing Space Plasmas and Particles. The site targets grades 9-14 and the equivalent in informal education and public outreach. Each ready-to-use product will be accompanied by a supporting explanation at a reading level matching the educational level of the concept. It will also have information on relevant science, technology, engineering, and mathematics (STEM) educational standards, activities, lesson plans, related products, links, and suggested uses. These products are intended to stand alone, making them adaptable to the widest range of uses, including scientist presentations, museum displays, educational websites and CDs, teacher professional development, and classroom use. This project is funded by a NASA Education and Public Outreach in Earth and Space Science (EPOESS) grant.

  14. Energetic particle instabilities in fusion plasmas

    CERN Document Server

    Sharapov, S E; Berk, H L; Borba, D N; Breizman, B N; Challis, C D; Classen, I G J; Edlund, E M; Eriksson, J; Fasoli, A; Fredrickson, E D; Fu, G Y; Garcia-Munoz, M; Gassner, T; Ghantous, K; Goloborodko, V; Gorelenkov, N N; Gryaznevich, M P; Hacquin, S; Heidbrink, W W; Hellesen, C; Kiptily, V G; Kramer, G J; Lauber, P; Lilley, M K; Lisak, M; Nabais, F; Nazikian, R; Nyqvist, R; Osakabe, M; von Thun, C Perez; Pinches, S D; Podesta, M; Porkolab, M; Shinohara, K; Schoepf, K; Todo, Y; Toi, K; Van Zeeland, M A; Voitsekhovich, I; White, R B; Yavorskij, V; TG, ITPA EP; Contributors, JET-EFDA

    2013-01-01

    Remarkable progress has been made in diagnosing energetic particle instabilities on present-day machines and in establishing a theoretical framework for describing them. This overview describes the much improved diagnostics of Alfven instabilities and modelling tools developed world-wide, and discusses progress in interpreting the observed phenomena. A multi-machine comparison is presented giving information on the performance of both diagnostics and modelling tools for different plasma conditions outlining expectations for ITER based on our present knowledge.

  15. Multiple harmonic ULF waves in the plasma sheet boundary layer observed by Cluster

    Science.gov (United States)

    Engebretson, M. J.; Kahlstorf, C. R. G.; Posch, J. L.; Keiling, A.; Walsh, A. P.; Denton, R. E.; Broughton, M. C.; Owen, C. J.; FornaçOn, K.-H.; RèMe, H.

    2010-12-01

    The passage of the Cluster satellites in a polar orbit through Earth's magnetotail has provided numerous observations of harmonically related Pc 1-2 ULF wave events, with the fundamental near the local proton cyclotron frequency Ωcp. Broughton et al. (2008) reported observations by Cluster of three such events in the plasma sheet boundary layer, and used the wave telescope technique to determine that their wave vectors k were nearly perpendicular to B. This paper reports the results of a search for such waves throughout the 2003 Cluster tail passage. During the 4 month period of July-October 2003, 35 multiple-harmonic wave events were observed, all in the plasma sheet boundary layer (PSBL). From the first observed event (22 July) to the last (28 October), 13 of Cluster's 42 tail passes had at least one event. The wave events were rather evenly distributed from XGSE = -7 RE out to the Cluster apogee distance of -18 RE, with one event observed at -4 RE. ZGSE for these events ranged from -10 to -3 RE and +3 to +7 RE (i.e., there were no events for ∣Z∣ elevated fluxes of counterstreaming ions with energies ranging from ˜3 to 30 keV, and elevated fluxes of electrons with energies ranging from 0.25 to ˜5 keV. Analysis of plasma parameters suggests that although waves occurred only when the ion beta exceeded 0.1 (somewhat larger than typical for the PSBL), ion particle pressure may be of more physical importance in controlling wave occurrence. Electron distributions were more isotropic in pitch angles than the ion distributions, but some evidence of counterstreaming electrons was detected in 83% of the events. The ions also showed clear signatures of shell-like or ring-like distributions; i.e., with reduced fluxes below the energy of maximum flux. The suprathermal ion fluxes were asymmetric in all events studied, with more ions streaming earthward (for events both north and south of the central plasma sheet). Good agreement between the observed frequency of the

  16. Thinning and functionalization of few-layer graphene sheets by CF4 plasma treatment

    KAUST Repository

    Shen, Chao

    2012-05-24

    Structural changes of few-layer graphene sheets induced by CF4 plasma treatment are studied by optical microscopy and Raman spectroscopy, together with theoretical simulation. Experimental results suggest a thickness reduction of few-layer graphene sheets subjected to prolonged CF4 plasma treatment while plasma treatment with short time only leads to fluorine functionalization on the surface layer by formation of covalent bonds. Raman spectra reveal an increase in disorder by physical disruption of the graphene lattice as well as functionalization during the plasma treatment. The F/CF3 adsorption and the lattice distortion produced are proved by theoretical simulation using density functional theory, which also predicts p-type doping and Dirac cone splitting in CF4 plasma-treated graphene sheets that may have potential in future graphene-based micro/nanodevices.

  17. Understanding the focusing of charged particle for 2D sheet beam in a cusped magnetic field

    CERN Document Server

    Banerjee, Tusharika S; Reddy, K T V

    2016-01-01

    The requirement of axial magnetic field for focusing and transportation of sheet beam using cusped magnets is less as compared to solenoid magnetic fields which is uniform. There is often some confusion about how a cusped magnetic field focuses high current density sheet beam because it is generally understood that non-uniform magnetic field cannot guide the particle beam along its axis of propagation .In this paper, we perform simple analysis of the dynamics of sheet beam in a cusped magnetic field with single electron model and emphasize an intuitive understanding of interesting features (as beam geometry, positioning of permanent magnets, particle radius,particle velocity,radius of curvature of particle inside cusped magnetic field)

  18. Bi-directional electrons in the near-Earth plasma sheet

    Directory of Open Access Journals (Sweden)

    K. Shiokawa

    Full Text Available We have studied the occurrence characteristics of bi-directional electron pitch angle anisotropy (enhanced flux in field-aligned directions, F^ /F|| > 1.5 at energies of 0.1–30 keV using plasma and magnetic field data from the AMPTE/IRM satellite in the near-Earth plasma sheet. The occurrence rate increases in the tailward direction from XGSM = - 9 RE to - 19 RE . The occurrence rate is also enhanced in the midnight sector, and furthermore, whenever the elevation angle of the magnetic field is large while the magnetic field intensity is small, B ~ 15 nT. From these facts, we conclude that the bi-directional electrons in the central plasma sheet are produced mainly in the vicinity of the neutral sheet and that the contribution from ionospheric electrons is minor. A high occurrence is also found after earthward high-speed ion flows, suggesting Fermi-type field-aligned electron acceleration in the neutral sheet. Occurrence characteristics of bi-directional electrons in the plasma sheet boundary layer are also discussed.

    Key words. Magnetospheric physics (magnetospheric configuration and dynamics; magnetotail; plasma sheet

  19. PLASMA ENERGETIC PARTICLES SIMULATION CENTER (PEPSC)

    Energy Technology Data Exchange (ETDEWEB)

    Berk, Herbert L.

    2014-05-23

    The main effort of the Texas group was to develop theoretical and simplified numerical models to understand chirping phenomena often seen for Alfven and geodesic acoustic waves in experimental plasmas such as D-III-D, NSTX and JET. Its main numerical effort was to modify the AEGIS code, which was originally developed as an eigenvalue solver. To apply to the chirping problem this code has to be able to treat the linear response to the continuum and the response of the plasma to external drive or to an internal drive that comes from the formation of phase space chirping structures. The theoretical underpinning of this investigation still needed to be more fully developed to understand how to best formulate the theoretical problem. Considerable progress was made on this front by B.N. Breizman and his collaborators and a new reduced model was developed by H. L. Berk and his PhD student, G. Wang which can be uses as simplified model to describe chirping in a large aspect ratio tokamak. This final report will concentrate on these two directions that were developed as well as results that were found in the work with the AEGIS code and in the progress in developing a novel quasi-linear formulation for a description of Alfvenic modes destabilized by energetic particles, such as alpha particles in a burning plasma.

  20. Anisotropic Equilibrium and Ballooning Mode Analysis in the Tail Plasma Sheet.

    Science.gov (United States)

    Lee, Dae-Young

    This thesis is a theoretical study about the Earth's tail plasma sheet with regard to two aspects: the equilibrium structure for the anisotropic pressure, and the ideal-MHD ballooning stability. By adopting a stretched magnetotail model where ion motions are generally nonadiabatic, and assuming that the anisotropy resides only in the electron pressure tensor, it is shown that the magnetic field lines with rm p_| > p_| are less stretched than the isotropic cases. As the parallel pressure p_| exceeds the perpendicular pressure p_| approaching the conventional marginal firehose limit, rm p_| = p{_ |} + B^2/ mu_0, the magnetic field lines are more and more stretched. It is also shown that the current density is highly enhanced at the same limit, a situation that might be subject to a microscopic instability. However, we also emphasize that such an enhancement in the current density is heavily localized near the z = 0 plane, and thus it is unclear if such a microscopic instability can significantly alter the global configuration of the tail. It is further argued, in terms of the radius of the field curvature versus the particle's gyroradius, that the conventional adiabatic description of electrons may become questionable, very close to the conventional marginal firehose limit. To study the ideal-MHD ballooning mode, we first adopt a hard ionospheric boundary condition where the perturbation is required to vanish at the ionospheric foot points. For such a hard boundary condition, an "untypical" magnetic field configuration is found to be unstable to a ballooning mode that is antisymmetric about the equatorial plane while most of the "typical" tail plasma-sheet configurations are stable against the ideal-MHD ballooning mode. The unstable magnetic field model, however, does not look like the average observation-based model, but rather resembles some of the characteristics of the steady-state magnetic field models by Hau (1989, 1991). In addition, a physical argument is

  1. Study of the turbulence in the central plasma sheet using the CLUSTER satellite data

    Science.gov (United States)

    Stepanova, M.; Arancibia Riveros, K.; Bosqued, J.; Antonova, E.

    2008-05-01

    Recent studies are shown that the turbulent processes in the space plasmas are very important. It includes the behavior of the plasma sheet plasma during geomagnetic substorms and storms. Study of the plasma turbulence in the central plasma sheet was made using the CLUSTER satellite mission data. For this studies we used the Cluster Ion Spectrometry experiment (CIS), and fluxgate magnetometer (FGM) data for studying fluctuations of the plasma bulk velocity and geomagnetic field fluctuations for different levels of geomagnetic activity and different locations inside the plasma sheet. Case studies for the orbits during quiet geomagnetic conditions, different phases of geomagnetic substroms and storms showed that the properties of plasma turbulence inside the sheet differ significantly for all afore mentioned cases. Variations in the probability distribution functions, flatness factors, local intermittency measure parameters, and eddy diffusion coefficients indicate that the turbulence increases significantly during substorm growth and expansion phases and decreases slowly to the initial level during the recovery phase. It became even stronger during the storm main phase.

  2. Engineering tubular bone using mesenchymal stem cell sheets and coral particles

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Wenxin [Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, No.229 North Taibai Road, Xi’an 710069 (China); Ma, Dongyang [Department of Oral and Maxillofacial Surgery, Lanzhou General Hospital, Lanzhou Command of PLA, BinHe 333 South Road, Lanzhou 730052 (China); Yan, Xingrong; Liu, Liangqi; Cui, Jihong; Xie, Xin; Li, Hongmin [Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, No.229 North Taibai Road, Xi’an 710069 (China); Chen, Fulin, E-mail: chenfl@nwu.edu.cn [Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, No.229 North Taibai Road, Xi’an 710069 (China)

    2013-04-19

    Highlights: • We developed a novel engineering strategy to solve the limitations of bone grafts. • We fabricated tubular constructs using cell sheets and coral particles. • The composite constructs showed high radiological density and compressive strength. • These characteristics were similar to those of native bone. -- Abstract: The development of bone tissue engineering has provided new solutions for bone defects. However, the cell-scaffold-based approaches currently in use have several limitations, including low cell seeding rates and poor bone formation capacity. In the present study, we developed a novel strategy to engineer bone grafts using mesenchymal stem cell sheets and coral particles. Rabbit bone marrow mesenchymal stem cells were continuously cultured to form a cell sheet with osteogenic potential and coral particles were integrated into the sheet. The composite sheet was then wrapped around a cylindrical mandrel to fabricate a tubular construct. The resultant tubular construct was cultured in a spinner-flask bioreactor and subsequently implanted into a subcutaneous pocket in a nude mouse for assessment of its histological characteristics, radiological density and mechanical property. A similar construct assembled from a cell sheet alone acted as a control. In vitro observations demonstrated that the composite construct maintained its tubular shape, and exhibited higher radiological density, compressive strength and greater extracellular matrix deposition than did the control construct. In vivo experiments further revealed that new bone formed ectopically on the composite constructs, so that the 8-week explants of the composite sheets displayed radiological density similar to that of native bone. These results indicate that the strategy of using a combination of a cell sheet and coral particles has great potential for bone tissue engineering and repairing bone defects.

  3. A Modified Porous Titanium Sheet Prepared by Plasma-Activated Sintering for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Yukimichi Tamaki

    2010-01-01

    Full Text Available This study aimed to develop a contamination-free porous titanium scaffold by a plasma-activated sintering within an originally developed TiN-coated graphite mold. The surface of porous titanium sheet with or without a coated graphite mold was characterized. The cell adhesion property of porous titanium sheet was also evaluated in this study. The peak of TiC was detected on the titanium sheet processed with the graphite mold without a TiN coating. Since the titanium fiber elements were directly in contact with the carbon graphite mold during processing, surface contamination was unavoidable event in this condition. The TiC peak was not detectable on the titanium sheet processed within the TiN-coated carbon graphite mold. This modified plasma-activated sintering with the TiN-coated graphite mold would be useful to fabricate a contamination-free titanium sheet. The number of adherent cells on the modified titanium sheet was greater than that of the bare titanium plate. Stress fiber formation and the extension of the cells were observed on the titanium sheets. This modified titanium sheet is expected to be a new tissue engineering material in orthopedic bone repair.

  4. A statistical study of the THEMIS satellite data for plasma sheet electrons carrying auroral upward field-aligned currents

    Science.gov (United States)

    Lee, S.; Shiokawa, K.; McFadden, J. P.

    2010-12-01

    The magnetospheric electron precipitation along the upward field-aligned currents without the potential difference causes diffuse aurora, and the magnetospheric electrons accelerated by a field-aligned potential difference cause the intense and bright type of aurora, namely discrete aurora. In this study, we are trying to find out when and where the aurora can be caused with or without electron acceleration. We statistically investigate electron density, temperature, thermal current, and conductivity in the plasma sheet using the data from the electrostatic analyzer (ESA) onboard the THEMIS-D satellite launched in 2007. According to Knight (Planet. Space Sci., 1973) and Lyons (JGR, 1980), the thermal current, jth(∝ nT^(1/2) where n is electron density and T is electron temperature in the plasma sheet), represents the upper limit to field aligned current that can be carried by magnetospheric electrons without field-aligned potential difference. The conductivity, K(∝ nT^(-1/2)), represents the efficiency of the upward field-aligned current (j) that the field-aligned potential difference (V) can produce (j=KV). Therefore, estimating jth and K in the plasma sheet is important in understanding the ability of plasma sheet electrons to carry the field-aligned current which is driven by various magnetospheric processes such as flow shear and azimuthal pressure gradient. Similar study was done by Shiokawa et al. (2000) based on the auroral electron data obtained by the DMSP satellites above the auroral oval and the AMPTE/IRM satellite in the near Earth plasma sheet at 10-18 Re on February-June 1985 and March-June 1986 during the solar minimum. The purpose of our study is to examine auroral electrons with pitch angle information inside 12 Re where Shiokawa et al. (2000) did not investigate well. For preliminary result, we found that in the dawn side inner magnetosphere (source of the region 2 current), electrons can make sufficient thermal current without field

  5. Rubber sheet strewn with TiO2 particles: Photocatalytic activity and recyclability

    Institute of Scientific and Technical Information of China (English)

    Chaval Sriwong; Sumpun Wongnawa; Orasa Patarapaiboolchai

    2012-01-01

    A new method for the preparation of rubber sheet strewn with titanium dioxide particles(TiO2-strewn sheet)is presented.This simple and low cost method is based on the use of TiO2 powder(Degussa P25)being strewn onto the sheet made from rubber latex(60% HA)through a steel sieve.The characteristic of the TiO2-strewn sheet was studied by using scanning electron microscopy/energy dispersive X-ray spectrometer(SEM/EDS)and X-ray diffractometer(XRD)techniques.The photocatalytic activity of TiO2-strewn rubber sheet was evaluated using Indigo Carmine(IC)dye as a model for organic dye pollutant in water.The results showed that the TiO2-strewn sheet could degrade IC dye solution under UV light irradiation.The effects of pH,initial concentration,and the intensity of UV light on the photodegradation were also investigated.Kinetics of the photocatalytic degradation was of the first-order reaction.The used TiO2-strewn sheet can be recovered and reused.The recycling uses did not require any cleaning between successive uses and no decline in the photodegradation efficiency was observed compared with freshly prepared TiO2-strewn sheet.

  6. Rubber sheet strewn with TiO2 particles: photocatalytic activity and recyclability.

    Science.gov (United States)

    Sriwong, Chaval; Wongnawa, Sumpun; Patarapaiboolchai, Orasa

    2012-01-01

    A new method for the preparation of rubber sheet strewn with titanium dioxide particles (TiO2-strewn sheet) is presented. This simple and low cost method is based on the use of TiO2 powder (Degussa P25) being strewn onto the sheet made from rubber latex (60% HA) through a steel sieve. The characteristic of the TiO2-strewn sheet was studied by using scanning electron microscopy/energy dispersive X-ray spectrometer (SEM/EDS) and X-ray diffractometer (XRD) techniques. The photocatalytic activity of TiO2-strewn rubber sheet was evaluated using Indigo Carmine (IC) dye as a model for organic dye pollutant in water. The results showed that the TiO2-strewn sheet could degrade IC dye solution under UV light irradiation. The effects of pH, initial concentration, and the intensity of UV light on the photodegradation were also investigated. Kinetics of the photocatalytic degradation was of the first-order reaction. The used TiO2-strewn sheet can be recovered and reused. The recycling uses did not require any cleaning between successive uses and no decline in the photodegradation efficiency was observed compared with freshly prepared TiO2-strewn sheet.

  7. Additional acceleration of solar-wind particles in current sheets of the heliosphere

    Energy Technology Data Exchange (ETDEWEB)

    Zharkova, V. [Northumbria Univ., Newcastle upon Tyne (United Kingdom). Dept. of Mathematics and Information Systems; Khabarova, O. [RAS (IZMIRAN), Moscow (Russian Federation). Heliophysical Lab.

    2015-09-01

    Particles of fast solar wind in the vicinity of the heliospheric current sheet (HCS) or in a front of interplanetary coronal mass ejections (ICMEs) often reveal very peculiar energy or velocity profiles, density distributions with double or triple peaks, and well-defined streams of electrons occurring around or far away from these events. In order to interpret the parameters of energetic particles (both ions and electrons) measured by the WIND spacecraft during the HCS crossings, a comparison of the data was carried out with 3-D particle-in-cell (PIC) simulations for the relevant magnetic topology (Zharkova and Khabarova, 2012). The simulations showed that all the observed particle-energy distributions, densities, ion peak velocities, electron pitch angles and directivities can be fitted with the same model if the heliospheric current sheet is in a status of continuous magnetic reconnection. In this paper we present further observations of the solar-wind particles being accelerated to rather higher energies while passing through the HCS and the evidence that this acceleration happens well before the appearance of the corotating interacting region (CIR), which passes through the spacecraft position hours later. We show that the measured particle characteristics (ion velocity, electron pitch angles and the distance at which electrons are turned from the HCS) are in agreement with the simulations of additional particle acceleration in a reconnecting HCS with a strong guiding field as measured by WIND. A few examples are also presented showing additional acceleration of solarwind particles during their passage through current sheets formed in a front of ICMEs. This additional acceleration at the ICME current sheets can explain the anticorrelation of ion and electron fluxes frequently observed around the ICME's leading front. Furthermore, it may provide a plausible explanation of the appearance of bidirectional ''strahls'' (field-aligned most

  8. Long-term variations in the plasma sheet ion composition and substorm occurrence over 23 years

    Science.gov (United States)

    Nosé, Masahito

    2016-12-01

    The Geotail satellite has been operating for almost two solar cycles (~23 years) since its launch in July 1992. The satellite carries the energetic particle and ion composition (EPIC) instrument that measures the energetic ion flux (9.4-212 keV/e) and enables the investigation of long-term variations of the ion composition in the plasma sheet for solar cycles 22-24. From the statistical analysis of the EPIC data, we find that (1) the plasma ion mass ( M) is approximately 1.1 amu during the solar minimum, whereas it increases to 1.5-2.7 amu during the solar maximum; (2) the increases in M seem to have two components: a raising of the baseline levels (~1.5 amu) and a large transient enhancement (~1.8-2.7 amu); (3) the baseline level change of M correlates well with the Mg II index, which is a good proxy for the solar extreme ultraviolet (EUV) or far ultraviolet (FUV) irradiance; and (4) the large transient enhancement of M is caused by strong magnetic storms. We also study the long-term variations of substorm occurrences in 1992-2015 that are evaluated with the number of Pi2 pulsations detected at the Kakioka observatory. The results suggest no clear correlation between the substorm occurrence and the Mg II index. Instead, when the substorms are classified into externally triggered events and non-triggered events, the number of the non-triggered events and the Mg II index are negatively correlated. We interpret these results that the increase in the solar EUV/FUV radiation enhances the supply of ionospheric ions (He+ and O+ ions) into the plasma sheet to increase M, and the large M may suppress spontaneous plasma instabilities initiating substorms and decrease the number of the non-triggered substorms. The present analysis using the unprecedentedly long-term dataset covering ~23 years provides additional observational evidence that heavy ions work to prevent the occurrence of substorms.

  9. Investigation of scaling properties of a thin current sheet by means of particle trajectories study

    CERN Document Server

    Sasunov, Yu L; Alexeev, I I; Belenkaya, E S; Semenov, V S; Kubyshkin, I V; Mingalev, O V

    2015-01-01

    A thin current sheet (TCS), with the width of an order of thermal proton gyroradius, appears a fundamental physical object which plays an important role in structuring of major magnetospheric current systems (magnetotail, magnetodisk, etc.). The TCSs are nowadays under extensive study by means of space missions and theoretical models. We consider a simple model of the TCS separating two half-spaces occupied by a homogenous magnetic field of opposite sign tangential to the TCS; a small normal component of the magnetic field is prescribed. An analytical solution for the electric current and plasma density in the close vicinity of the TCS has been obtained and compared with numerical simulation. The number density and the electric current profiles have two maxima each. The characteristic spatial scale $z_S$ of the maxima location was investigated as a function of initial pitch-angle of an incoming charge particle. The effect of the thermal dispersion of the incoming proton beam have been taken into consideration...

  10. Thermal Structure and Dynamics in Supra-arcade Downflows and Flare Plasma Sheets

    Science.gov (United States)

    Reeves, K.; Hanneman, W.; Freed, M.; McKenzie, D. E.

    2014-12-01

    During a long duration solar flare, a hot plasma sheet is commonly formed above the flare loops. Often produced within this sheet are down-flowing voids referred to as supra-arcade downflows, thought to be the products of a patchy reconnection process. Models differ on the question of whether the downflows should be hotter than the surrounding plasma or not. We use imaging data from Hinode/XRT and SDO/AIA to determine the thermal structure of the plasma sheet and downflows. We find that the temperatures of the plasma within the downflows are either roughly the same as or lower than the surrounding fan plasma. This result implies that a mechanism for forming the voids that involves a sunward directed hydrodynamic shock pattern combined with perpendicular magnetic shock is unlikely. Additionally, we use the high cadence AIA data to trace the velocity fields in these regions through the use of a local correlation tracking algorithm. Through these measurements, we can determine areas of diverging velocity fields, as well as velocity shear fields and correlate them with temperature changes in order to understand the heating mechanisms in the plasma sheet. This work is supported by under contract SP02H1701R from Lockheed-Martin to SAO, contract NNM07AB07C from NASA to SAO and NASA grant numbers NNX13AG54G and NNX14AD43G

  11. In situ observations of reconnection and associated particle energization in turbulent plasmas

    Science.gov (United States)

    Retinò, A.; Sundkvist, D.; Vaivads, A.; Sahraoui, F.

    2012-04-01

    Magnetic reconnection occurs in turbulent plasma within a large number of volume-filling thin current sheets. Such reconnection efficiently dissipates the magnetic energy of turbulent plasma, resulting in substantial particle heating. Turbulent reconnection is also considered to play an important role for the acceleration of supra-thermal particles. Yet the details of energy dissipation and particle energization during turbulent reconnection, as well their dependence on turbulence properties, are not completely understood from an experimental point of view due to the scarcity of in situ observations. Here we present recent Cluster spacecraft observations of reconnection in different near-Earth turbulent regions (solar wind, magnetosheath, magnetotail) and we discuss the properties of particle energization therein.

  12. Laser Plasma Particle Accelerators: Large Fields for Smaller Facility Sources

    Energy Technology Data Exchange (ETDEWEB)

    Geddes, Cameron G.R.; Cormier-Michel, Estelle; Esarey, Eric H.; Schroeder, Carl B.; Vay, Jean-Luc; Leemans, Wim P.; Bruhwiler, David L.; Cary, John R.; Cowan, Ben; Durant, Marc; Hamill, Paul; Messmer, Peter; Mullowney, Paul; Nieter, Chet; Paul, Kevin; Shasharina, Svetlana; Veitzer, Seth; Weber, Gunther; Rubel, Oliver; Ushizima, Daniela; Bethel, Wes; Wu, John

    2009-03-20

    Compared to conventional particle accelerators, plasmas can sustain accelerating fields that are thousands of times higher. To exploit this ability, massively parallel SciDAC particle simulations provide physical insight into the development of next-generation accelerators that use laser-driven plasma waves. These plasma-based accelerators offer a path to more compact, ultra-fast particle and radiation sources for probing the subatomic world, for studying new materials and new technologies, and for medical applications.

  13. Spontaneous pairing and cooperative movements of micro-particles in a two dimensional plasma crystal

    Energy Technology Data Exchange (ETDEWEB)

    Zhdanov, S. K. [Max Planck Institute for extraterrestrial Physics, D-85741 Garching (Germany); Couëdel, L., E-mail: lenaic.couedel@univ-amu.fr [CNRS, Université d' Aix-Marseille, PIIM UMR 7345, 13397 Marseille Cedex 20 (France); Nosenko, V.; Thomas, H. M. [Forschungsgruppe Komplexe Plasmen, Deutsches Zentrum fur Luft-und-Raumfahrt, Oberpfaffenhofen (Germany); Morfill, G. E. [Max Planck Institute for extraterrestrial Physics, D-85741 Garching (Germany); BMSTU Centre for Plasma Science and Technology, Moscow (Russian Federation)

    2015-05-15

    In an argon plasma of 20 W rf discharge at a pressure of 1.38 Pa, a stable highly ordered monolayer of microparticles is suspended. We observe spontaneous particle pairing when suddenly reducing the gas pressure. Special types of dynamical activity, in particular, entanglement and cooperative movements of coupled particles have been registered. In the course of the experiment first appeared single vertical pairs of particles, in further they gradually accumulated causing melting of the entire crystal. To record pairing events, the particle suspension is side-view imaged using a vertically extended laser sheet. The long-lasting pre-melting phase assured the credible recording and identification of isolated particle pairs. The high monolayer charge density is crucial to explain the spontaneous pairing events observed in our experiments as the mutual repulsion between the particles comprising the monolayer make its vertical extend thicker.

  14. Survey of 0. 1- to 16-keV/e plasma sheet ion composition

    Energy Technology Data Exchange (ETDEWEB)

    Lennartsson, W.; Shelley, E.G.

    1986-03-01

    A large statistical survey of the 0.1- to 16-keV/e plasma sheet ion composition has been carried out using data obtained by the Plasma Composition Experiment on ISEE 1 between 10 and 23 R/sub E/ during 1978 and 1979. This survey includes more than 10 times the quantity of data used in earlier studies of the same topic and makes it possible to investigate in finer detail the relationship between the ion composition and the substorm activity. The larger data base also makes it possible for the first time to study the spatial distribution of the principal ion species. As found in previous studies, the ion composition has a large variance at any given value of the AE index, but a number of distinct trends emerge when the data are averaged at each activity level. During quiet conditions the plasma sheet is dominated by ions of solar origin (H/sup +/ and He/sup + +/), as found in earlier studies, and these ions are most numerous during extended periods of very low activity (AE< or approx. =30 ..gamma..). The quiet time density of these ions is particularly large in the flanks of the plasma sheet (GSM Yapprox. +- 10 R/sub E/), where it is about twice as large as it is near the central axis of the plasma sheet (Y = Z = 0). In contrast, the energy of these ions peaks near the central axis.

  15. Early results of microwave transmission experiments through an overly dense rectangular plasma sheet with microparticle injection

    Science.gov (United States)

    Gillman, Eric D.; Amatucci, W. E.

    2014-06-01

    These experiments utilize a linear hollow cathode to create a dense, rectangular plasma sheet to simulate the plasma layer surrounding vehicles traveling at hypersonic velocities within the Earth's atmosphere. Injection of fine dielectric microparticles significantly reduces the electron density and therefore lowers the electron plasma frequency by binding a significant portion of the bulk free electrons to the relatively massive microparticles. Measurements show that microwave transmission through this previously overly dense, impenetrable plasma layer increases with the injection of alumina microparticles approximately 60 μm in diameter. This method of electron depletion is a potential means of mitigating the radio communications blackout experienced by hypersonic vehicles.

  16. Plasma polymer-functionalized silica particles for heavy metals removal.

    Science.gov (United States)

    Akhavan, Behnam; Jarvis, Karyn; Majewski, Peter

    2015-02-25

    Highly negatively charged particles were fabricated via an innovative plasma-assisted approach for the removal of heavy metal ions. Thiophene plasma polymerization was used to deposit sulfur-rich films onto silica particles followed by the introduction of oxidized sulfur functionalities, such as sulfonate and sulfonic acid, via water-plasma treatments. Surface chemistry analyses were conducted by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy. Electrokinetic measurements quantified the zeta potentials and isoelectric points (IEPs) of modified particles and indicated significant decreases of zeta potentials and IEPs upon plasma modification of particles. Plasma polymerized thiophene-coated particles treated with water plasma for 10 min exhibited an IEP of less than 3.5. The effectiveness of developed surfaces in the adsorption of heavy metal ions was demonstrated through copper (Cu) and zinc (Zn) removal experiments. The removal of metal ions was examined through changing initial pH of solution, removal time, and mass of particles. Increasing the water plasma treatment time to 20 min significantly increased the metal removal efficiency (MRE) of modified particles, whereas further increasing the plasma treatment time reduced the MRE due to the influence of an ablation mechanism. The developed particulate surfaces were capable of removing more than 96.7% of both Cu and Zn ions in 1 h. The combination of plasma polymerization and oxidative plasma treatment is an effective method for the fabrication of new adsorbents for the removal of heavy metals.

  17. Energetic particles in spherical tokamak plasmas

    Science.gov (United States)

    McClements, K. G.; Fredrickson, E. D.

    2017-05-01

    Spherical tokamaks (STs) typically have lower magnetic fields than conventional tokamaks, but similar mass densities. Suprathermal ions with relatively modest energies, in particular beam-injected ions, consequently have speeds close to or exceeding the Alfvén velocity, and can therefore excite a range of Alfvénic instabilities which could be driven by (and affect the behaviour of) fusion α-particles in a burning plasma. STs heated with neutral beams, including the small tight aspect ratio tokamak (START), the mega amp spherical tokamak (MAST), the national spherical torus experiment (NSTX) and Globus-M, have thus provided an opportunity to study toroidal Alfvén eigenmodes (TAEs), together with higher frequency global Alfvén eigenmodes (GAEs) and compressional Alfvén eigenmodes (CAEs), which could affect beam current drive and channel fast ion energy into bulk ions in future devices. In NSTX GAEs were correlated with a degradation of core electron energy confinement. In MAST pulses with reduced magnetic field, CAEs were excited across a wide range of frequencies, extending to the ion cyclotron range, but were suppressed when hydrogen was introduced to the deuterium plasma, apparently due to mode conversion at ion-ion hybrid resonances. At lower frequencies fishbone instabilities caused fast particle redistribution in some MAST and NSTX pulses, but this could be avoided by moving the neutral beam line away from the magnetic axis or by operating the plasma at either high density or elevated safety factor. Fast ion redistribution has been observed during GAE avalanches on NSTX, while in both NSTX and MAST fast ions were transported by saturated kink modes, sawtooth crashes, resonant magnetic perturbations and TAEs. The energy dependence of fast ion redistribution due to both sawteeth and TAEs has been studied in Globus-M. High energy charged fusion products are unconfined in present-day STs, but have been shown in MAST to provide a useful diagnostic of beam ion

  18. Oxygen plasma-treated thermoresponsive polymer surfaces for cell sheet engineering.

    Science.gov (United States)

    Shimizu, Kazunori; Fujita, Hideaki; Nagamori, Eiji

    2010-06-01

    Although cell sheet tissue engineering is a potent and promising method for tissue engineering, an increase of mechanical strength of a cell sheet is needed for easy manipulation of it during transplantation or 3D tissue fabrication. Previously, we developed a cell sheet-polymer film complex that had enough mechanical strength that can be manipulated even by tweezers (Fujita et al., 2009. Biotechnol Bioeng 103(2): 370-377). We confirmed the polymer film involving a temperature sensitive polymer and extracellular matrix (ECM) proteins could be removed by lowering temperature after transplantation, and its potential use in regenerative medicine was demonstrated. However, the use of ECM proteins conflicted with high stability in long-term storage and low cost. In the present study, to overcome these drawbacks, we employed the oxygen plasma treatment instead of using the ECM proteins. A cast and dried film of thermoresponsive poly-N-isopropylacrylamide (PNIPAAm) was fabricated and treated with high-intensity oxygen plasma. The cells became possible to adhere to the oxygen plasma-treated PNIPAAm surface, whereas could not to the inherent surface of bulk PNIPAAm without treatment. Characterizations of the treated surface revealed the surface had high stability. The surface roughness, wettability, and composition were changed, depending on the plasma intensity. Interestingly, although bulk PNIPAAm layer had thermoresponsiveness and dissolved below lower critical solution temperature (LCST), it was found that the oxygen plasma-treated PNIPAAm surface lost its thermoresponsiveness and remained insoluble in water below LCST as a thin layer. Skeletal muscle C2C12 cells could be cultured on the oxygen plasma-treated PNIPAAm surface, a skeletal muscle cell sheet with the insoluble thin layer could be released in the medium, and thus the possibility of use of the cell sheet for transplantation was demonstrated.

  19. In Situ Observations of Ion Scale Current Sheets and Associated Electron Heating in Turbulent Space Plasmas

    Science.gov (United States)

    Chasapis, A.; Retino, A.; Sahraoui, F.; Greco, A.; Vaivads, A.; Khotyaintsev, Y. V.; Sundkvist, D. J.; Canu, P.

    2014-12-01

    We present a statistical study of ion-scale current sheets in turbulent space plasma. The study was performed using in situ measurements from the Earth's magnetosheath downstream of the quasi-parallel shock. Intermittent structures were identified using the Partial Variance of Increments method. We studied the distribution of the identified structures as a function of their magnetic shear angle, the PVI index and the electron heating. The properties of the observed current sheets were different for high (>3) and low (3) structures that accounted for ~20% of the total. Those current sheets have high magnetic shear (>90 degrees) and were observed mostly in close proximity to the bow shock with their numbers reducing towards the magnetopause. Enhancement of the estimated electron temperature within these current sheets suggest that they are important for local electron heating and energy dissipation.

  20. Improvement of warm formability of Al-Mg sheet alloys containing coarse second-phase particles

    Institute of Scientific and Technical Information of China (English)

    Arne; K; DAHLE; Amit; K; GHOSH

    2009-01-01

    Several alloying elements involving Zr, Cu, Zn and Sc were added to Al-Mg sheet alloys in order to obtain an excellent combination of high strength and good high-temperature formability. Microstruc-tural examination showed that coarse intermetallic particles were formed in the microstructure and their amounts changed with variations of the alloying elements. During warm rolling of thermome-chanical treatments prior to warm deformation, the coarse particles initiated cracks, decreasing the warm formability. For healing the crack damage and further improving the warm formability, a process of hot isothermal press was developed and optimized to the sheet alloys. With this process, the biaxial stretch formability at 350℃ was improved by 22% for an aluminum alloy containing a large amount of coarse particles.

  1. Improvement of warm formability of Al-Mg sheet alloys containing coarse second-phase particles

    Institute of Scientific and Technical Information of China (English)

    HanLiang ZHU; Arne K DAHLE; Amit K GHOSH

    2009-01-01

    Several alloying elements involving Zr, Cu, Zn and Sc were added to AI-Mg sheet alloys in order to obtain an excellent combination of high strength and good high-temperature formability. Microstruc-tural examination showed that coarse intermetallic particles were formed in the microstructure and their amounts changed with variations of the alloying elements. During warm rolling of thermome-chanical treatments prior to warm deformation, the coarse particles initiated cracks, decreasing the warm formability. For healing the crack damage and further improving the warm formability, a process of hot isothermal press was developed and optimized to the sheet alloys. With this process, the biaxial stretch formability at 350"(2 was improved by 22% for an aluminum alloy containing a large amount of coarse particles.

  2. Beam-driven, Plasma-based Particle Accelerators

    CERN Document Server

    Muggli, P

    2016-01-01

    We briefly give some of the characteristics of the beam-driven, plasma-based particle accelerator known as the plasma wakefield accelerator (PWFA). We also mention some of the major results that have been obtained since the birth of the concept. We focus on high-energy particle beams where possible.

  3. Beam-driven, Plasma-based Particle Accelerators

    CERN Document Server

    Muggli, P.

    2016-01-01

    We briefly give some of the characteristics of the beam-driven, plasma-based particle accelerator known as the plasma wakefield accelerator (PWFA). We also mention some of the major results that have been obtained since the birth of the concept. We focus on high-energy particle beams where possible.

  4. Cylindrical particle manipulation and negative spinning using a nonparaxial Hermite-Gaussian light-sheet beam

    Science.gov (United States)

    Mitri, F. G.

    2016-10-01

    Based on the angular spectrum decomposition method (ASDM), a nonparaxial solution for the Hermite-Gaussian (HG m ) light-sheet beam of any order m is derived. The beam-shape coefficients (BSCs) are expressed in a compact form and computed using the standard Simpson’s rule for numerical integration. Subsequently, the analysis is extended to evaluate the longitudinal and transverse radiation forces as well as the spin torque on an absorptive dielectric cylindrical particle in 2D without any restriction to a specific range of frequencies. The dynamics of the cylindrical particle are also examined based on Newton’s second law of motion. The numerical results show that a Rayleigh or Mie cylindrical particle can be trapped, pulled or propelled in the optical field depending on its initial position in the cross-sectional plane of the HG m light-sheet. Moreover, negative or positive axial spin torques can arise depending on the choice of the non-dimensional size parameter ka (where k is the wavenumber and a is the radius of the cylinder) and the location of the absorptive cylinder in the beam. This means that the HG m light-sheet beam can induce clockwise or anti-clockwise rotations depending on its shift from the center of the cylinder. In addition, individual vortex behavior can arise in the cross-sectional plane of wave propagation. The present analysis presents an analytical model to predict the optical radiation forces and torque induced by a HG m light-sheet beam on an absorptive cylinder for applications in optical light-sheet tweezers, optical micro-machines, particle manipulation and opto-fluidics to name a few areas of research.

  5. Observations of energetic electrons /E no less than about 200 keV/ in the earth's magnetotail - Plasma sheet and fireball observations

    Science.gov (United States)

    Baker, D. N.; Stone, E. C.

    1977-01-01

    An earlier paper by the authors (1976) has reported on energetic electron anisotropies observed in conjunction with the acceleration regions identified by Frank et al., (1976). The present paper gives more detailed analyses of observations in the distant plasma sheet, including specific features of intensities, energy spectra, and pitch angle distributions of the very energetic electrons associated with intense plasma particle events, with energies ranging between 50 eV and 45 keV, detected with an electron/isotope spectrometer aboard the earth-orbiting spacecraft Imp 8. Two domains are considered: the plasma sheet and the regions near and within the localized magnetotail acceleration regions known as the fireball regions. The instrumentation used offered a number of observational advantages over many previous studies, including inherently low background, large geometric factors, excellent species identification, good angular distribution measurement capability, and availability of high resolution of differential intensities.

  6. Resonant scattering of plasma sheet electrons leading to diffuse auroral precipitation: 1. Evaluation for electrostatic electron cyclotron harmonic waves

    Science.gov (United States)

    Ni, Binbin; Thorne, Richard M.; Horne, Richard B.; Meredith, Nigel P.; Shprits, Yuri Y.; Chen, Lunjin; Li, Wen

    2011-04-01

    Using statistical wave power spectral profiles obtained from CRRES and the latitudinal distributions of wave propagation modeled by the HOTRAY code, a quantitative analysis has been performed on the scattering of plasma sheet electrons into the diffuse auroral zone by multiband electrostatic electron cyclotron harmonic (ECH) emissions near L = 6 within the 0000-0600 MLT sector. The results show that ECH wave scattering of plasma sheet electrons varies from near the strong diffusion rate (timescale of an hour or less) during active times with peak wave amplitudes of an order of 1 mV/m to very weak scattering (on the timescale of >1 day) during quiet conditions with typical wave amplitudes of tenths of mV/m. However, for the low-energy (˜100 eV to below 2 keV) electron population mainly associated with the diffuse auroral emission, ECH waves are only responsible for rapid pitch angle diffusion (occasionally near the limit of strong diffusion) for a small portion of the electron population with pitch angles αeq 70°. Computations of the bounce-averaged coefficients of momentum diffusion and (pitch angle, momentum) mixed diffusion indicate that both mixed diffusion and energy diffusion of plasma sheet electrons due to ECH waves are very small compared to pitch angle diffusion and that ECH waves have little effect on local electron acceleration. Consequently, the multiple harmonic ECH emissions cannot play a dominant role in the occurrence of diffuse auroral precipitation near L = 6, and other wave-particle interaction mechanisms, such as whistler mode chorus-driven resonant scattering, are required to explain the global distribution of diffuse auroral precipitation and the formation of the pancake distribution in the inner magnetosphere.

  7. Kink-like mode of a double gradient instability in a compressible plasma current sheet

    Science.gov (United States)

    Korovinskiy, D.B.; Ivanova, V.V.; Erkaev, N.V.; Semenov, V.S.; Ivanov, I.B.; Biernat, H.K.; Zellinger, M.

    2011-01-01

    A linear MHD instability of the electric current sheet, characterized by a small normal magnetic field component, varying along the sheet, is investigated. The tangential magnetic field component is modeled by a hyperbolic function, describing Harris-like variations of the field across the sheet. For this problem, which is formulated in a 3D domain, the conventional compressible ideal MHD equations are applied. By assuming Fourier harmonics along the electric current, the linearized 3D equations are reduced to 2D ones. A finite difference numerical scheme is applied to examine the time evolution of small initial perturbations of the plasma parameters. This work is an extended numerical study of the so called “double gradient instability”, – a possible candidate for the explanation of flapping oscillations in the magnetotail current sheet, which has been analyzed previously in the framework of a simplified analytical approach for an incompressible plasma. The dispersion curve is obtained for the kink-like mode of the instability. It is shown that this curve demonstrates a quantitative agreement with the previous analytical result. The development of the instability is investigated also for various enhanced values of the normal magnetic field component. It is found that the characteristic values of the growth rate of the instability shows a linear dependence on the square root of the parameter, which scales uniformly the normal component of the magnetic field in the current sheet. PMID:22053125

  8. A study of the formation and dynamics of the Earth's plasma sheet using ion composition data

    Energy Technology Data Exchange (ETDEWEB)

    Lennartsson, O.W.

    1994-04-01

    Over two years of data from the Lockheed Plasma Composition Experiment on the ISEE 1 spacecraft, covering ion energies between 100 eV/e and about 16 keV/e, have been analyzed in an attempt to extract new information about three geophysical issues: (1) solar wind penetration of the Earth's magnetic tail; (2) relationship between plasma sheet and tail lobe ion composition; and (3) possible effects of heavy terrestrial ions on plasma sheet stability.

  9. Particle acceleration by ultra-intense laser-plasma interactions

    CERN Document Server

    Nakajima, K

    2002-01-01

    The mechanism of particle acceleration by ultra-increase laser-plasma interaction is explained. Laser light can generate very high electric field by focusing with electromagnetic field matched phase with frequency. 1018 W/cm sup 2 laser light produce about 3 TV/m electric field. Many laser accelerators, which particle acceleration method satisfies phase matching particle and electric field, are proposed. In these accelerators, the Inverse Cherenkov Accelerator, Inverse FEL Accelerator and Laser-Plasma Accelerator are explained. Three laser-plasma acceleration mechanisms: Plasma Beat Wave Accelerator, Laser Wake-Field Accelerator (LWFA) and Self-Modulated LWFA, showed particle acceleration by experiments. By developing a high speed Z pinch capillary-plasma optical waveguide, 2.2 TW and 90 fs laser pulse could be propagated 2 cm at 40 mu m focusing radius in 1999. Dirac acceleration or ultra-relativistic ponderomotive acceleration mechanism can increase energy exponentially. (S.Y.)

  10. Preparation of spherical hollow alumina particles by thermal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Wonkyung [Department of Chemical Engineering, INHA University, 253 Yonghyun-dong, Nam-gu, Incheon 402‐751 (Korea, Republic of); Regional Innovation Center for Environmental Technology of Thermal Plasma (RIC-ETTP), INHA University, 253 Yonghyun-dong, Nam-gu, Incheon 402‐751 (Korea, Republic of); Choi, Sooseok [Center for Advance Research in Fusion Reactor Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151‐742 (Korea, Republic of); Oh, Seung-Min [Daejoo Electronic Materials Co., 1236‐10 Jeongwang-dong, Siheung-si, Kyunggi-do 429‐848 (Korea, Republic of); Park, Dong-Wha, E-mail: dwpark@inha.ac.kr [Department of Chemical Engineering, INHA University, 253 Yonghyun-dong, Nam-gu, Incheon 402‐751 (Korea, Republic of); Regional Innovation Center for Environmental Technology of Thermal Plasma (RIC-ETTP), INHA University, 253 Yonghyun-dong, Nam-gu, Incheon 402‐751 (Korea, Republic of)

    2013-02-01

    Spherical hollow particles were prepared from solid alumina powders using DC arc thermal plasma, and then spray coating was performed with the as-prepared particles. Operating variables for the hollow particle preparation process were additional plasma gas, input power, and carrier gas flow rate. The spherical hollow alumina particles were produced in the case of using additive gas of H{sub 2} or N{sub 2}, while alumina surface was hardly molten in the pure argon thermal plasma. In addition, the hollow particles were well produced in high power and low carrier gas conditions due to high melting point of alumina. Hollow structure was confirmed by focused ion beam-scanning electron microscopy analysis. Morphology and size distribution of the prepared particles that were examined by field emission-scanning electron microscopy and phase composition of the particles was characterized by X-ray diffraction. In the spray coating process, the as-prepared hollow particles showed higher deposition rate. - Highlights: ► Spherical hollow alumina powder was prepared by non-transferred DC arc plasma. ► Diatomic gasses were added in Ar plasma for high power. ► Prepared hollow alumina powder was efficient for the plasma spray coating.

  11. Scale size and life time of energy conversion regions observed by Cluster in the plasma sheet

    Directory of Open Access Journals (Sweden)

    M. Hamrin

    2009-11-01

    Full Text Available In this article, and in a companion paper by Hamrin et al. (2009 [Occurrence and location of concentrated load and generator regions observed by Cluster in the plasma sheet], we investigate localized energy conversion regions (ECRs in Earth's plasma sheet. From more than 80 Cluster plasma sheet crossings (660 h data at the altitude of about 15–20 RE in the summer and fall of 2001, we have identified 116 Concentrated Load Regions (CLRs and 35 Concentrated Generator Regions (CGRs. By examining variations in the power density, E·J, where E is the electric field and J is the current density obtained by Cluster, we have estimated typical values of the scale size and life time of the CLRs and the CGRs. We find that a majority of the observed ECRs are rather stationary in space, but varying in time. Assuming that the ECRs are cylindrically shaped and equal in size, we conclude that the typical scale size of the ECRs is 2 RE≲ΔSECR≲5 RE. The ECRs hence occupy a significant portion of the mid altitude plasma sheet. Moreover, the CLRs appear to be somewhat larger than the CGRs. The life time of the ECRs are of the order of 1–10 min, consistent with the large scale magnetotail MHD simulations of Birn and Hesse (2005. The life time of the CGRs is somewhat shorter than for the CLRs. On time scales of 1–10 min, we believe that ECRs rise and vanish in significant regions of the plasma sheet, possibly oscillating between load and generator character. It is probable that at least some of the observed ECRs oscillate energy back and forth in the plasma sheet instead of channeling it to the ionosphere.

  12. Particle simulation of neoclassical transport in the plasma Edge

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C.S. [Department of Physics, Korea Advanced Institute of Science and Technology (Korea); Ku, S. [Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, NY (United States); Department of Physics, Korea Advanced Institute of Science and Technology (Korea)

    2006-09-15

    Particle-in-cell is a popular technique for a global five dimensional numerical simulation of the neoclassical plasma phenomena in a toroidal plasma. In this paper, we briefly review the physical and mathematical aspects of the modern neoclassical particle simulation methodology for a plasma edge simulation and present representative results recently obtained from XGC (X-point included Guiding Center) code. The strength and weakness in the modern neoclassical particle simulation techniques will also be discussed. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. A Statistical study of plasma sheet oscillations with kinetic ballooning/interchange instability signatures using THEMIS spacecraft

    Science.gov (United States)

    Jurisic, Mirjana; Panov, Evgeny; Nakamura, Rumi; Baumjohann, Wolfgang

    2016-04-01

    We use THEMIS data from 2010-2012 tail seasons to collect observations of plasma sheet oscillations with kinetic ballooning/interchange instability (BICI) signatures. Over seventy observations with closely located THEMIS probes P3-P5 reveal that BICI-like plasma sheet oscillations may appear at different magnetic local time. For these, we derive background plasma sheet parameters such as BZ, δBZ/δx and plasma beta, and investigate solar wind conditions. We also estimate the proper parameters of BICI-like oscillations such as frequency and amplitude. Based on this, we search for a relation between the background plasma sheet parameters and the proper parameters of BICI-like oscillations.

  14. Geotail observations of temperature anisotropy of the two-component protons in the dusk plasma sheet

    Directory of Open Access Journals (Sweden)

    M. N. Nishino

    2007-03-01

    Full Text Available In search for clues towards the understanding of the cold plasma sheet formation under northward IMF, we study the temperature anisotropy of the two-component protons in the plasma sheet near the dusk low-latitude boundary observed by the Geotail spacecraft. The two-component protons result from mixing of the cold component from the solar wind and the hot component of the magnetospheric origin, and may be the most eloquent evidence for the transport process across the magnetopause. The cold component occasionally has a strong anisotropy in the dusk flank, and the sense of the anisotropy depends on the observed locations: the parallel temperature is enhanced in the tail flank while the perpendicular temperature is enhanced on the dayside. The hot component is nearly isotropic in the tail while the perpendicular temperature is enhanced on the dayside. We discuss possible mechanism that can lead to the observed temperature anisotropies.

  15. Distribution of energetic oxygen and hydrogen in the near-Earth plasma sheet

    CERN Document Server

    Kronberg, E A; Haaland, S E; Daly, P W; Delcourt, D C; Luo, H; Kistler, L M; Dandouras, I

    2016-01-01

    The spatial distributions of different ion species are useful indicators for plasma sheet dynamics. In this statistical study based on 7 years of Cluster observations, we establish the spatial distributions of oxygen ions and protons at energies from 274 to 955 keV, depending on geomagnetic and solar wind (SW) conditions. Compared with protons, the distribution of energetic oxygen has stronger dawn-dusk asymmetry in response to changes in the geomagnetic activity. When the interplanetary magnetic field (IMF) is directed southward, the oxygen ions show significant acceleration in the tail plasma sheet. Changes in the SW dynamic pressure ($\\mathit{P}_{dyn}$) affect the oxygen and proton intensities in the same way. The energetic protons show significant intensity increases at the near-Earth duskside during disturbed geomagnetic conditions, enhanced SW $\\mathit{P}_{dyn}$, and southward IMF, implying there location of effective inductive acceleration mechanisms and a strong duskward drift due to the increase of t...

  16. Synthesis of silicon nitride particles in pulsed Rf plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Buss, R.J.; Babu, S.V.

    1995-11-01

    Silicon nitride (hydrogenated) particles are synthesized using a pulsed 13.56 Mhz glow discharge. The plasma is modulated with a square-wave on/off cycle of varying period to study the growth kinetics. In situ laser light scattering and ex situ particle analysis are used to study the nucleation and growth. For SiH{sub 4}/Ar and SiH{sub 4}/NH{sub 3} plasmas, an initial very rapid growth phase is followed by slower growth, approaching the rate of thin film deposition on adjacent flat surfaces. The average particle size can be controlled in the 10-100 nm range by adjusting the plasma-on time. The size dispersion of the particles is large and is consistent with a process of continuous nucleation during the plasma-on period. The large polydispersity is also reported for silicon particles from silane and differs from that reported in other laboratories. The silicon nitride particle morphology is compared to that of silicon and silicon carbide particles generated by the same technique. Whereas Si particles appear as rough clusters of smaller subunits, the SiC particles are smooth spheres, and the Si{sub 3}N{sub 4} particles are smooth but non-spherical. Post-plasma oxidation kinetics of the particles are studied with FTIR and are consistent with a hydrolysis mechanism proposed in earlier work with continuous plasmas. Heat treatment of the powder in an ammonia atmosphere results in the elimination of hydrogen, rendering the silicon nitride resistant to atmospheric oxidation.

  17. Effect of the initial plasma parameters on the structure of the current sheets developing in two-dimensional magnetic fields with a null line

    Science.gov (United States)

    Ostrovskaya, G. V.; Frank, A. G.; Bogdanov, S. Yu.

    2010-07-01

    The effect of the initial plasma parameters on the structure of the plasma of the current sheets that form in two-dimensional magnetic fields with a null line is studied by holographic interferometry. The evolution of the plasma sheets that develop in an initial low-density plasma, where a gas is mainly ionized by a pulse current passing through the plasma and initiating the formation of a current sheet, has been comprehensively studied for the first time. At the early stage of evolution, the spatial structure of such a plasma sheet differs substantially from the classic current sheets forming in a dense plasma. Nevertheless, extended plasma sheets with similar parameters form eventually irrespective of the initial plasma density.

  18. Plasma sheet ion composition at various levels of geomagnetic and solar activity

    Science.gov (United States)

    Lennartsson, W.

    1987-08-01

    The data obtained in the earth's plasma sheet by the Plasma Composition Experiment on the ISEE-1 spacecraft are briefly reexamined. The data are shown in the form of statistically averaged bulk parameters for the four major ions H(+), He(2+), He(+), and O(+) to illustrate the apparent mixture of solar and terrestrial ions, a mixture that varies with geomagnetic and other conditions. Some major differences in the statistical properties of different ions, which may have a bearing on the physics of the solar wind-magnetosphere interaction, are highlighted.

  19. On the problem of Plasma Sheet Boundary Layer identification from plasma moments in Earth's magnetotail

    Directory of Open Access Journals (Sweden)

    E. E. Grigorenko

    2012-09-01

    Full Text Available The problem of identification of the interface region between the lobe and the Plasma Sheet (PS – the Plasma Sheet Boundary Layer (PSBL – using ion moments and magnetic field data often arises in works devoted to statistical studies of various PSBL phenomena. Our experience in the identification of this region based on the analysis of ion velocity distribution functions demonstrated that plasma parameters, such as the ion density and bulk velocity, the plasma beta or the dynamic pressure vary widely depending on the state of magnetotail activity. For example, while field-aligned beams of accelerated ions are often observed propagating along the lobeward edge of the PSBL there are times when no signatures of these beams could be observed. In the last case, a spacecraft moving from the lobe region to the PS registers almost isotropic PS-like ion velocity distribution. Such events may be classified as observations of the outer PS region. In this paper, we attempt to identify ion parameter ranges or their combinations that result in a clear distinction between the lobe, the PSBL and the adjacent PS or the outer PS regions. For this we used 100 crossings of the lobe-PSBL-PS regions by Cluster spacecraft (s/c made in different periods of magnetotail activity. By eye inspection of the ion distribution functions we first identify and separate the lobe, the PSBL and the adjacent PS or outer PS regions and then perform a statistical study of plasma and magnetic field parameters in these regions. We found that the best results in the identification of the lobe-PSBL boundary are reached when one uses plasma moments, namely the ion bulk velocity and density calculated not for the entire energy range, but for the energies higher than 2 keV. In addition, we demonstrate that in many cases the plasma beta fails to correctly identify and separate the PSBL and the adjacent PS or the outer PS regions.

  20. Formation and evolution of flapping and ballooning waves in magnetospheric plasma sheet

    Science.gov (United States)

    Ma, J. Z. G.; Hirose, A.

    2016-05-01

    By adopting Lembége & Pellat's 2D plasma-sheet model, we investigate the flankward flapping motion and Sunward ballooning propagation driven by an external source (e.g., magnetic reconnection) produced initially at the sheet center. Within the ideal MHD framework, we adopt the WKB approximation to obtain the Taylor-Goldstein equation of magnetic perturbations. Fourier spectral method and Runge-Kutta method are employed in numerical simulations, respectively, under the flapping and ballooning conditions. Studies expose that the magnetic shears in the sheet are responsible for the flapping waves, while the magnetic curvature and the plasma gradient are responsible for the ballooning waves. In addition, the flapping motion has three phases in its temporal development: fast damping phase, slow recovery phase, and quasi-stabilized phase; it is also characterized by two patterns in space: propagating wave pattern and standing wave pattern. Moreover, the ballooning modes are gradually damped toward the Earth, with a wavelength in a scale size of magnetic curvature or plasma inhomogeneity, only 1-7% of the flapping one; the envelops of the ballooning waves are similar to that of the observed bursty bulk flows moving toward the Earth.

  1. Modification of Plasma Solitons by Resonant Particles

    DEFF Research Database (Denmark)

    Karpman, Vladimir; Lynov, Jens-Peter; Michelsen, Poul;

    1979-01-01

    Experimental and numerical results are compared with new theoretical results describing soliton propagation and deformation in a strongly magnetized, plasma-loaded waveguide.......Experimental and numerical results are compared with new theoretical results describing soliton propagation and deformation in a strongly magnetized, plasma-loaded waveguide....

  2. Coagulation of dust particles in a plasma

    Science.gov (United States)

    Horanyi, M.; Goertz, C. K.

    1990-01-01

    The electrostatic charge of small dust grains in a plasma in which the temperature varies in time is discussed, pointing out that secondary electron emission might introduce charge separation. If the sign of the charge on small grains is opposite to that on big ones, enhanced coagulation can occur which will affect the size distribution of grains in a plasma. Two scenarios where this process might be relevant are considered: a hot plasma environment with temperature fluctuations and a cold plasma environment with transient heating events. The importance of the enhanced coagulation is uncertain, because the plasma parameters in grain-producing environments such as a molecular cloud or a protoplanetary disk are not known. It is possible, however, that this process is the most efficient mechanism for the growth of grains in the size range of 0.1-500 microns.

  3. A Hybrid Method with Deviational Particles for Spatial Inhomogeneous Plasma

    CERN Document Server

    Yan, Bokai

    2015-01-01

    In this work we propose a Hybrid method with Deviational Particles (HDP) for a plasma modeled by the inhomogeneous Vlasov-Poisson-Landau system. We split the distribution into a Maxwellian part evolved by a grid based fluid solver and a deviation part simulated by numerical particles. These particles, named deviational particles, could be both positive and negative. We combine the Monte Carlo method proposed in \\cite{YC15}, a Particle in Cell method and a Macro-Micro decomposition method \\cite{BLM08} to design an efficient hybrid method. Furthermore, coarse particles are employed to accelerate the simulation. A particle resampling technique on both deviational particles and coarse particles is also investigated and improved. The efficiency is significantly improved compared to a PIC-MCC method, especially near the fluid regime.

  4. Abnormal Kinetic Energy of Charged Dust Particles in Plasmas

    NARCIS (Netherlands)

    Norman, G.; Stegailov, V.; Timofeev, A.

    A mechanism of the increase of the average kinetic energy of charged dust particles in gas discharge plasmas is suggested. Particle charge fluctuation is the reason for the appearance of forced resonance, which heals vertical oscillations. The energy transfer from vertical oscillations to the

  5. Abnormal Kinetic Energy of Charged Dust Particles in Plasmas

    NARCIS (Netherlands)

    Norman, G.; Stegailov, V.; Timofeev, A.

    2010-01-01

    A mechanism of the increase of the average kinetic energy of charged dust particles in gas discharge plasmas is suggested. Particle charge fluctuation is the reason for the appearance of forced resonance, which heals vertical oscillations. The energy transfer from vertical oscillations to the horizo

  6. Effect of Inductive Coil Geometry and Current Sheet Trajectory of a Conical Theta Pinch Pulsed Inductive Plasma Accelerator

    Science.gov (United States)

    Hallock, Ashley K.; Polzin, Kurt A.; Bonds, Kevin W.; Emsellem, Gregory D.

    2011-01-01

    Results are presented demonstrating the e ect of inductive coil geometry and current sheet trajectory on the exhaust velocity of propellant in conical theta pinch pulsed induc- tive plasma accelerators. The electromagnetic coupling between the inductive coil of the accelerator and a plasma current sheet is simulated, substituting a conical copper frustum for the plasma. The variation of system inductance as a function of plasma position is obtained by displacing the simulated current sheet from the coil while measuring the total inductance of the coil. Four coils of differing geometries were employed, and the total inductance of each coil was measured as a function of the axial displacement of two sep- arate copper frusta both having the same cone angle and length as the coil but with one compressed to a smaller size relative to the coil. The measured relationship between total coil inductance and current sheet position closes a dynamical circuit model that is used to calculate the resulting current sheet velocity for various coil and current sheet con gura- tions. The results of this model, which neglects the pinching contribution to thrust, radial propellant con nement, and plume divergence, indicate that in a conical theta pinch ge- ometry current sheet pinching is detrimental to thruster performance, reducing the kinetic energy of the exhausting propellant by up to 50% (at the upper bound for the parameter range of the study). The decrease in exhaust velocity was larger for coils and simulated current sheets of smaller half cone angles. An upper bound for the pinching contribution to thrust is estimated for typical operating parameters. Measurements of coil inductance for three di erent current sheet pinching conditions are used to estimate the magnetic pressure as a function of current sheet radial compression. The gas-dynamic contribution to axial acceleration is also estimated and shown to not compensate for the decrease in axial electromagnetic acceleration

  7. Cluster and TC-1 observation of magnetic holes in the plasma sheet

    Directory of Open Access Journals (Sweden)

    W. J. Sun

    2012-03-01

    Full Text Available Magnetic holes with relatively small scale sizes, detected by Cluster and TC-1 in the magnetotail plasma sheet, are studied in this paper. It is found that these magnetic holes are spatial structures and they are not magnetic depressions generated by the flapping movement of the magnetotail current sheet. Most of the magnetic holes (93% were observed during intervals with Bz larger than Bx, i.e. they are more likely to occur in a dipolarized magnetic field topology. Our results also suggest that the occurrence of these magnetic holes might have a close relationship with the dipolarization process. The magnetic holes typically have a scale size comparable to the local proton Larmor radius and are accompanied by an electron energy flux enhancement at a 90° pitch angle, which is quite different from the previously observed isotropic electron distributions inside magnetic holes in the plasma sheet. It is also shown that most of the magnetic holes occur in marginally mirror-stable environments. Whether the plasma sheet magnetic holes are generated by the mirror instability related to ions or not, however, is unknown. Comparison of ratios, scale sizes and propagation direction of magnetic holes detected by Cluster and TC-1, suggests that magnetic holes observed in the vicinity of the TC-1 orbit (~7–12 RE are likely to be further developed than those observed by Cluster (~7–18 RE.

  8. Application of particle image velocimetry to dusty plasma systems

    Science.gov (United States)

    Williams, Jeremiah D.

    2016-06-01

    > Particle image velocimetry is a fluid measurement technique that has been used for more than 20 years to characterize the particle transport and thermal state of dusty plasma systems. This manuscript provides an overview of this diagnostic technique, highlighting the strengths and limitations that are associated with its use. Additionally, the variations of this technique that have been applied in the study of dusty plasma systems will be discussed, along with a small selection of measurements that can be made with the technique. Potential future directions for this diagnostic tool within the dusty plasma community will also be discussed.

  9. Charge fluctuations for particles on a surface exposed to plasma

    CERN Document Server

    Sheridan, T E

    2011-01-01

    We develop a stochastic model for the charge fluctuations on a microscopic dust particle resting on a surface exposed to plasma. We find in steady state that the fluctuations are normally distributed with a standard deviation that is proportional to $CT_{e})^{1/2}$, where $C$ is the particle-surface capacitance and $T_{e}$ is the plasma electron temperature. The time for an initially uncharged ensemble of particles to reach the steady state distribution is directly proportional to $CT_{e}$.

  10. Carbon dust particles in a beam-plasma discharge

    Science.gov (United States)

    Koval, O. A.; Vizgalov, V.; Shalpegin, A. V.

    2016-09-01

    This paper focuses on dynamics of micro-sized carbon dust grains in beam-plasma discharge (BPD) plasmas. It was demonstrated that injected dust particles can be captured and transported along the discharge. Longitudinal average velocity of the particles in the central area of the plasma column was 17 m/sec, and 2 m/sec in the periphery. Dust injection caused a decrease of emission intensity of metastable nitrogen molecular ion. This effect is suggested for a spectroscopy method for particles’ potential measurements. Five-micron radius carbon dust grains obtained potential above 500 V in the experiments on PR-2 installation, proving the feasibility of BPDs for the charging of fine dust particles up to high potential values, unattainable in similar plasma conditions.

  11. Plasma-filled rippled wall rectangular backward wave oscillator driven by sheet electron beam

    Indian Academy of Sciences (India)

    A Hadap; J Mondal; K C Mittal; K P Maheshwari

    2011-03-01

    Performance of the backward wave oscillator (BWO) is greatly enhanced with the introduction of plasma. Linear theory of the dispersion relation and the growth rate have been derived and analysed numerically for plasma-filled rippled wall rectangular waveguide driven by sheet electron beam. To see the effect of plasma on the TM01 cold wave structure mode and on the generated frequency, the parameters used are: relativistic factor = 1.5 (i.e. / = 0.741), average waveguide height 0 = 1.445 cm, axial corrugation period 0 = 1.67 cm, and corrugation amplitude = 0.225 cm. The plasma density is varied from zero to 2 × 1012 cm-3. The presence of plasma tends to raise the TM01 mode cut-off frequency (14 GH at 2 × 1012 cm-3 plasma density) relative to the vacuum cut-off frequency (5 GH) which also causes a decrease in the group velocity everywhere, resulting in a flattening of the dispersion relation. With the introduction of plasma, an enhancement in absolute instability was observed.

  12. Interaction potential of microparticles in a plasma: role of collisions with plasma particles.

    Science.gov (United States)

    Khrapak, S A; Ivlev, A V; Morfill, G

    2001-10-01

    The interaction potential of two charged microparticles in a plasma is studied. Violation of the plasma equilibrium around the dust particles due to plasma-particle inelastic collisions results in three effects: long-range (non-Yukawa) electrostatic repulsion, attraction due to ion shadowing, and attraction or repulsion due to neutral shadowing (depending on the sign of the temperature difference between the particle surface and neutral gas). An analytical expression for the total potential is obtained and compared with previous theoretical results. The relative contribution of these effects is studied in two limiting cases-an isotropic bulk plasma and the plasma sheath region. The results obtained are compared with existing experimental results on pair particle interaction. The possibility of the so-called dust molecule formation is discussed.

  13. Alfven Waves in a Plasma Sheet Boundary Layer Associated with Near-Tail Magnetic Reconnection

    Institute of Scientific and Technical Information of China (English)

    YUAN Zhi-Gang; DENG Xiao-Hua; PANG Ye; LI Shi-You; WANG Jing-Fang

    2007-01-01

    We report observations from Geotail satellite showing that large Poynting fluxes associated with Alfven waves in the plasma sheet boundary layer(PSBL) occur in the vicinity of the near-tail reconnection region on 10 December 1996.During the period of large Poynting fluxex,Geotail also observed strong tailward plasma flws.These observations demonstrate the importance of near-tail reconnection process as the energy source of Alfven waves in the PSBL.Strong tailward(Earthward)plasma flows ought to be an important candidate in generating Alfven waves.Furthermore,the strong pertutbations not only of the magnetic field but also of the electric field observed in the PSBL indicate that the PSBL plays an important role in the generation and propagation of the energy flux associated with Alfven waves.

  14. Three-Dimensional Simulation of Plasma Jet and Particle Groups in Plasma Spraying

    Institute of Scientific and Technical Information of China (English)

    FAN Qun-bo; WANG Lu; WANG Fu-chi

    2008-01-01

    The temperature field, velocity field, as well as species distribution in three-dimensional space are successfully calculated by establishing three-dimensional geometry model and solving plasma jet-substrate interaction equations, optimized particle trajecory models, as well as particle-particle heat transfer equations in three-dimensionalal space. Under typical working conditions, the flying trajectories and distribution of ZrO2 ceramic particles and Ni metal particles are also simulated. Results show that, the plasma jet becomes wider near the substrate, and the stochastic trajectory model is preferable to simulate the turbulent diffusion effect of particles. In addition, Ni metal particles penetrate relatively more deeply than ZrO2 ceramic particles due to larger density.

  15. Molecular Dynamic Studies of Particle Wake Potentials in Plasmas

    Science.gov (United States)

    Ellis, Ian; Graziani, Frank; Glosli, James; Strozzi, David; Surh, Michael; Richards, David; Decyk, Viktor; Mori, Warren

    2010-11-01

    Fast Ignition studies require a detailed understanding of electron scattering, stopping, and energy deposition in plasmas with variable values for the number of particles within a Debye sphere. Presently there is disagreement in the literature concerning the proper description of these processes. Developing and validating proper descriptions requires studying the processes using first-principle electrostatic simulations and possibly including magnetic fields. We are using the particle-particle particle-mesh (P^3M) code ddcMD to perform these simulations. As a starting point in our study, we examined the wake of a particle passing through a plasma. In this poster, we compare the wake observed in 3D ddcMD simulations with that predicted by Vlasov theory and those observed in the electrostatic PIC code BEPS where the cell size was reduced to .03λD.

  16. Self-confined particle pairs in complex plasmas.

    Science.gov (United States)

    Lisina, I I; Lisin, E A; Vaulina, O S; Petrov, O F

    2017-01-01

    The liquid-crystal type of phase transition in complex plasmas has been observed repeatedly. However, more studies need to be done on the liquid-vapor transition in complex plasmas. In this paper, the phenomenon of coupling (condensation) of particles into self-confined particle pairs in an anisotropic plasma medium with ion flow is considered analytically and numerically using the Langevin molecular dynamics method. We obtain the stability conditions of the pair (bound) state depending on the interaction parameters and particle kinetic energy. It was shown that the breakup of the particle pair is very sensitive to the ratio of particle charges; for example, it is determined by the influence of the upper particle on the ion flow around the lower one. We also show that a self-confined pair of particles exists even if their total kinetic energy is much greater than the potential well depth for the pair state. This phenomenon occurs due to velocity correlation of particles, which arises with the nonreciprocity of interparticle interaction.

  17. Single-sheet identification method of heavy charged particles using solid state nuclear track detectors

    Indian Academy of Sciences (India)

    M F Zaki; A Abdel-Naby; A Ahmed Morsy

    2007-08-01

    The theoretical and experimental investigations of the penetration of charged particles in matter played a very important role in the development of modern physics. Solid state nuclear track detectors have become one of the most important tools for many branches of science and technology. An attempt has been made to examine the suitability of the single-sheet particle identification technique in CR-39 and CN-85 polycarbonate by plotting track cone length vs. residual range for different heavy ions in these detectors. So, the maximum etchable ranges of heavy ions such as 93Nb, 86Kr and 4He in CR-39 and 4He and 132Xe in CN-85 polycarbonate have been determined. The ranges of these ions in these detectors have also been computed theoretically using the Henke–Benton program. A reasonably good agreement has been observed between the experimentally and theoretically computed values.

  18. Sheet-like assemblies of spherical particles with point-symmetrical patches.

    Science.gov (United States)

    Mani, Ethayaraja; Sanz, Eduardo; Roy, Soumyajit; Dijkstra, Marjolein; Groenewold, Jan; Kegel, Willem K

    2012-04-14

    We report a computational study on the spontaneous self-assembly of spherical particles into two-dimensional crystals. The experimental observation of such structures stabilized by spherical objects appeared paradoxical so far. We implement patchy interactions with the patches point-symmetrically (icosahedral and cubic) arranged on the surface of the particle. In these conditions, preference for self-assembly into sheet-like structures is observed. We explain our findings in terms of the inherent symmetry of the patches and the competition between binding energy and vibrational entropy. The simulation results explain why hollow spherical shells observed in some Keplerate-type polyoxometalates (POM) appear. Our results also provide an explanation for the experimentally observed layer-by-layer growth of apoferritin--a quasi-spherical protein.

  19. Relative contributions of terrestrial and solar wind ions in the plasma sheet

    Science.gov (United States)

    Lennartsson, W.; Sharp, R. D.

    A major uncertainty concerning the origins of plasma sheet ions is due to the fact that terrestrial H(+) can have similar fluxes and energies as H(+) from the solar wind. The situation is especially ambiguous during magnetically quiet conditions (AE less than 60 gamma) when H(+) typically contributes more than 90 percent of the plasma sheet ion population. In this study that problem is examined using a large data set obtained by the ISEE-1 Plasma Composition Experiment. The data suggest that one component of the H(+) increases in energy with increasing activity, roughly in proportion to 1/4 the energy of the He(++), whereas the other H(+) component has about the same energy at all activity levels, as do the O(+) and the He(+). If it is assumed that the H(+) of solar wind origin on the average has about the same energy-per-nucleon as the He(++), which is presumably almost entirely from the solar wind, then the data imply that as much as 20-30 percent of the H(+) can be of terrestrial origin even during quiet conditions.

  20. Relative contributions of terrestrial and solar wind ions in the plasma sheet

    Energy Technology Data Exchange (ETDEWEB)

    Lennartsson, W.; Sharp, R.D.

    1985-01-01

    A major uncertainty concerning the origins of plasma sheet ions is due to the fact that terrestrial H(+) can have similar fluxes and energies as H(+) from the solar wind. The situation is especially ambiguous during magnetically quiet conditions (AE less than 60 gamma) when H(+) typically contributes more than 90 percent of the plasma sheet ion population. In this study that problem is examined using a large data set obtained by the ISEE-1 Plasma Composition Experiment. The data suggest that one component of the H(+) increases in energy with increasing activity, roughly in proportion to 1/4 the energy of the He(++), whereas the other H(+) component has about the same energy at all activity levels, as do the O(+) and the He(+). If it is assumed that the H(+) of solar wind origin on the average has about the same energy-per-nucleon as the He(++), which is presumably almost entirely from the solar wind, then the data imply that as much as 20-30 percent of the H(+) can be of terrestrial origin even during quiet conditions.

  1. Survey of 0.1- to 16-keV/e plasma sheet ion composition

    Science.gov (United States)

    Lennartsson, W.; Shelley, E. G.

    1986-03-01

    An analysis is performed of all plasma sheet data collected in 1978-79 in order to discern statistical trends in the data. Attention is focused on the bulk parameters of 0.1-16 keV/e plasma sheet ions detected by the Plasma Composition Experiment on the ISEE 1 satellite. The data were collected at 10-23 earth radii, and are averaged for various levels of activity in the AE index. Solar H(+) and He(2+) ions dominate during quiet periods and possess energies similar to those of the solar wind when the quiet period lasts several hours. Increasing AE index values eventually lead to a replacement of the solar ions with terrestrial ions, particularly O(+), which can have an average energy density of 3-4 keV/e at every activity level. The solar ions, however, increase in energy as their density decreases. The O(+) density is highest near the local midnight and becomes the most numerous during highly disturbed conditions. Finally, the O(+) density was observed to increase by a factor of three over the monitoring period, possibly due to enhanced solar EUV radiation.

  2. Molecular processes in plasmas collisions of charged particles with molecules

    CERN Document Server

    Itikawa, Yukikazu

    2007-01-01

    Molecular Processes in Plasmas describes elementary collision processes in plasmas, particularly those involving molecules or molecular ions. Those collision processes (called molecular processes) maintain plasmas, produce reactive species and emissions, and play a key role in energy balance in plasmas or more specifically in determining the energy distribution of plasma particles. Many books on plasma physics mention the elementary processes, but normally rather briefly. They only touch upon the general feature or fundamental concept of the collision processes. On the other hand, there are many books on atomic and molecular physics, but most of them are too general or too detailed to be useful to people in the application fields. The present book enumerates all the possible processes in the collisions of electrons, as well as ions, with molecules. For each process, a compact but informative description of its characteristics is given together with illustrative examples. Since the author has much experience a...

  3. Energetic particle instabilities in fusion plasmas

    NARCIS (Netherlands)

    Sharapov, S. E.; Alper, B.; Berk, H. L.; Borba, D. N.; Breizman, B. N.; Challis, C. D.; Classen, I.G.J.; Edlund, E. M.; Eriksson, J.; Fasoli, A.; Fredrickson, E. D.; Fu, G. Y.; Garcia-Munoz, M.; Gassner, T.; Ghantous, K.; Goloborodko, V.; Gorelenkov, N. N.; Gryaznevich, M. P.; Hacquin, S.; Heidbrink, W. W.; Hellesen, C.; Kiptily, V. G.; Kramer, G. J.; Lauber, P.; Lilley, M. K.; Lisak, M.; Nabais, F.; Nazikian, R.; Nyqvist, R.; Osakabe, M.; C. Perez von Thun,; Pinches, S. D.; Podesta, M.; Porkolab, M.; Shinohara, K.; Schoepf, K.; Todo, Y.; Toi, K.; VanZeeland, M. A.; Voitsekhovich, I.; White, R. B.; Yavorskij, V.; ITPA EP TG Contributors,; JET-EFDA Contributors,

    2013-01-01

    Remarkable progress has been made in diagnosing energetic particle instabilities on present-day machines and in establishing a theoretical framework for describing them. This overview describes the much improved diagnostics of Alfvén instabilities and modelling tools developed world-wide, and discus

  4. Nonthermal Particle Acceleration in 3D Relativistic Magnetic Reconnection in Pair Plasma

    Science.gov (United States)

    Werner, Gregory R.; Uzdensky, Dmitri A.

    2017-07-01

    As a fundamental process converting magnetic to plasma energy in high-energy astrophysical plasmas, relativistic magnetic reconnection is a leading explanation for the acceleration of particles to the ultrarelativistic energies that are necessary to power nonthermal emission (especially X-rays and gamma-rays) in pulsar magnetospheres and pulsar wind nebulae, coronae and jets of accreting black holes, and gamma-ray bursts. An important objective of plasma astrophysics is therefore the characterization of nonthermal particle acceleration (NTPA) effected by reconnection. Reconnection-powered NTPA has been demonstrated over a wide range of physical conditions using large 2D kinetic simulations. However, its robustness in realistic 3D reconnection—in particular, whether the 3D relativistic drift-kink instability (RDKI) disrupts NTPA—has not been systematically investigated, although pioneering 3D simulations have observed NTPA in isolated cases. Here, we present the first comprehensive study of NTPA in 3D relativistic reconnection in collisionless electron-positron plasmas, characterizing NTPA as the strength of 3D effects is varied systematically via the length in the third dimension and the strength of the guide magnetic field. We find that, while the RDKI prominently perturbs 3D reconnecting current sheets, it does not suppress particle acceleration, even for zero guide field; fully 3D reconnection robustly and efficiently produces nonthermal power-law particle spectra closely resembling those obtained in 2D. This finding provides strong support for reconnection as the key mechanism powering high-energy flares in various astrophysical systems. We also show that strong guide fields significantly inhibit NTPA, slowing reconnection and limiting the energy available for plasma energization, yielding steeper and shorter power-law spectra.

  5. Fly ash particles spheroidization using low temperature plasma energy

    Science.gov (United States)

    Shekhovtsov, V. V.; Volokitin, O. G.; Kondratyuk, A. A.; Vitske, R. E.

    2016-11-01

    The paper presents the investigations on producing spherical particles 65-110 μm in size using the energy of low temperature plasma (LTP). These particles are based on flow ash produced by the thermal power plant in Seversk, Tomsk region, Russia. The obtained spherical particles have no defects and are characterized by a smooth exterior surface. The test bench is designed to produce these particles. With due regard for plasma temperature field distribution, it is shown that the transition of fly ash particles to a state of viscous flow occurs at 20 mm distance from the plasma jet. The X-ray phase analysis is carried out for the both original state of fly ash powders and the particles obtained. This analysis shows that fly ash contains 56.23 wt.% SiO2; 20.61 wt.% Al2O3 and 17.55 wt.% Fe2O3 phases that mostly contribute to the integral (experimental) intensity of the diffraction maximum. The LTP treatment results in a complex redistribution of the amorphous phase amount in the obtained spherical particles, including the reduction of O2Si, phase, increase of O22Al20 and Fe2O3 phases and change in Al, O density of O22Al20 chemical unit cell.

  6. Charge neutrality of fine particle (dusty) plasmas and fine particle cloud under gravity

    Science.gov (United States)

    Totsuji, Hiroo

    2017-03-01

    The enhancement of the charge neutrality due to the existence of fine particles is shown to occur generally under microgravity and in one-dimensional structures under gravity. As an application of the latter, the size and position of fine particle clouds relative to surrounding plasmas are determined under gravity.

  7. Studying astrophysical particle acceleration with laser-driven plasmas

    Science.gov (United States)

    Fiuza, Frederico

    2016-10-01

    The acceleration of non-thermal particles in plasmas is critical for our understanding of explosive astrophysical phenomena, from solar flares to gamma ray bursts. Particle acceleration is thought to be mediated by collisionless shocks and magnetic reconnection. The microphysics underlying these processes and their ability to efficiently convert flow and magnetic energy into non-thermal particles, however, is not yet fully understood. By performing for the first time ab initio 3D particle-in-cell simulations of the interaction of both magnetized and unmagnetized laser-driven plasmas, it is now possible to identify the optimal parameters for the study of particle acceleration in the laboratory relevant to astrophysical scenarios. It is predicted for the Omega and NIF laser conditions that significant non-thermal acceleration can occur during magnetic reconnection of laser-driven magnetized plasmas. Electrons are accelerated by the electric field near the X-points and trapped in contracting magnetic islands. This leads to a power-law tail extending to nearly a hundred times the thermal energy of the plasma and that contains a large fraction of the magnetic energy. The study of unmagnetized interpenetrating plasmas also reveals the possibility of forming collisionless shocks mediated by the Weibel instability on NIF. Under such conditions, both electrons and ions can be energized by scattering out of the Weibel-mediated turbulence. This also leads to power-law spectra that can be detected experimentally. The resulting experimental requirements to probe the microphysics of plasma particle acceleration will be discussed, paving the way for the first experiments of these important processes in the laboratory. As a result of these simulations and theoretical analysis, there are new experiments being planned on the Omega, NIF, and LCLS laser facilities to test these theoretical predictions. This work was supported by the SLAC LDRD program and DOE Office of Science, Fusion

  8. Piezoresistive Effect in Plasma-Doping of Graphene Sheet for High-Performance Flexible Pressure Sensing Application.

    Science.gov (United States)

    Haniff, M A S M; Hafiz, S M; Huang, N M; Rahman, S A; Wahid, K A A; Syono, M I; Azid, I A

    2017-05-03

    This paper presents a straightforward plasma treatment modification of graphene with an enhanced piezoresistive effect for the realization of a high-performance pressure sensor. The changes in the graphene in terms of its morphology, structure, chemical composition, and electrical properties after the NH3/Ar plasma treatment were investigated in detail. Through a sufficient plasma treatment condition, our studies demonstrated that plasma-treated graphene sheet exhibits a significant increase in sensitivity by one order of magnitude compared to that of the unmodified graphene sheet. The plasma-doping introduced nitrogen (N) atoms inside the graphene structure and was found to play a significant role in enhancing the pressure sensing performance due to the tunneling behavior from the localized defects. The high sensitivity and good robustness demonstrated by the plasma-treated graphene sensor suggest a promising route for simple, low-cost, and ultrahigh resolution flexible sensors.

  9. Pseudopotentials of the particles interactions in complex plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ramazanov, T. S.; Moldabekov, Zh. A.; Dzhumagulova, K. N.; Muratov, M. M. [Al Farabi Kazakh National University, IETP, Tole bi 96a, Almaty 050012 (Kazakhstan)

    2011-10-15

    This article discusses the effective interaction potentials in a complex dusty plasma. The interaction of electrons with atoms and the interaction between dusty particles are studied by the method of the dielectric response function. In the effective interaction, potential between electron and atom the quantum effects of diffraction were taken into account. On the curve of the interaction potential between dust particles under certain conditions the oscillations can be observed.

  10. From dressed particle to dressed mode in plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Sanae-I. [Kyushu Univ., Research Inst. for Applied Mechanics, Kasuga, Fukuoka (Japan); Itoh, Kimitaka [National Inst. for Fusion Science, Toki, Gifu (Japan)

    2002-05-01

    A theoretical method to analyze the strong turbulence in far-nonequilibrium plasma is discussed. In this approach, a test mode is treated being dressed with interactions with other modes. Nonlinear dispersion relation of the dressed mode and statistical treatment of turbulence is briefly explained. Analogue to the method of dressed particle, which has given Balescu-Lenard collision operator for inter-particle collisions, is mentioned. (author)

  11. A Theoretical Model of Pinching Current Sheet in Low-beta Plasmas

    CERN Document Server

    Takeshige, Satoshi; Shibata, Kazunari

    2015-01-01

    Magnetic reconnection is an important physical process in various explosive phenomena in the universe. In the previous studies, it was found that fast re- connection takes place when the thickness of a current sheet becomes on the order of a microscopic length such as the ion larmor radius or the ion inertial length. In this study, we investigated the pinching process of a current sheet by the Lorentz force in a low-{\\beta} plasma using one-dimensional magnetohydrodynam- ics (MHD) simulations. It is known that there is an exact self-similar solution for this problem that neglects gas pressure. We compared the non-linear MHD dynamics with the analytic self-similar solution. From the MHD simulations, we found that with the gas pressure included the implosion process deviates from the analytic self-similar solution as t {\\rightarrow} t 0, where t 0 is the explosion time when the thickness of a current sheet of the analytic solution becomes 0. We also found a pair of MHD fast-mode shocks are generated and propaga...

  12. An exact collisionless equilibrium for the Force-Free Harris Sheet with low plasma beta

    Energy Technology Data Exchange (ETDEWEB)

    Allanson, O., E-mail: oliver.allanson@st-andrews.ac.uk; Neukirch, T., E-mail: tn3@st-andrews.ac.uk; Wilson, F., E-mail: fw237@st-andrews.ac.uk; Troscheit, S., E-mail: s.troscheit@st-andrews.ac.uk [School of Mathematics and Statistics, University of St Andrews, St. Andrews, KY16 9SS (United Kingdom)

    2015-10-15

    We present a first discussion and analysis of the physical properties of a new exact collisionless equilibrium for a one-dimensional nonlinear force-free magnetic field, namely, the force-free Harris sheet. The solution allows any value of the plasma beta, and crucially below unity, which previous nonlinear force-free collisionless equilibria could not. The distribution function involves infinite series of Hermite polynomials in the canonical momenta, of which the important mathematical properties of convergence and non-negativity have recently been proven. Plots of the distribution function are presented for the plasma beta modestly below unity, and we compare the shape of the distribution function in two of the velocity directions to a Maxwellian distribution.

  13. An exact collisionless equilibrium for the Force-Free Harris Sheet with low plasma beta

    CERN Document Server

    Allanson, O; Wilson, F; Troscheit, S

    2015-01-01

    We present a first discussion and analysis of the physical properties of a new exact collisionless equilibrium for a one-dimensional nonlinear force-free magnetic field, namely the Force-Free Harris Sheet. The solution allows any value of the plasma beta, and crucially below unity, which previous nonlinear force-free collisionless equilibria could not. The distribution function involves infinite series of Hermite Polynomials in the canonical momenta, of which the important mathematical properties of convergence and non-negativity have recently been proven. Plots of the distribution function are presented for the plasma beta modestly below unity, and we compare the shape of the distribution function in two of the velocity directions to a Maxwellian distribution.

  14. Particle based plasma simulation for an ion engine discharge chamber

    Science.gov (United States)

    Mahalingam, Sudhakar

    Design of the next generation of ion engines can benefit from detailed computer simulations of the plasma in the discharge chamber. In this work a complete particle based approach has been taken to model the discharge chamber plasma. This is the first time that simplifying continuum assumptions on the particle motion have not been made in a discharge chamber model. Because of the long mean free paths of the particles in the discharge chamber continuum models are questionable. The PIC-MCC model developed in this work tracks following particles: neutrals, singly charged ions, doubly charged ions, secondary electrons, and primary electrons. The trajectories of these particles are determined using the Newton-Lorentz's equation of motion including the effects of magnetic and electric fields. Particle collisions are determined using an MCC statistical technique. A large number of collision processes and particle wall interactions are included in the model. The magnetic fields produced by the permanent magnets are determined using Maxwell's equations. The electric fields are determined using an approximate input electric field coupled with a dynamic determination of the electric fields caused by the charged particles. In this work inclusion of the dynamic electric field calculation is made possible by using an inflated plasma permittivity value in the Poisson solver. This allows dynamic electric field calculation with minimal computational requirements in terms of both computer memory and run time. In addition, a number of other numerical procedures such as parallel processing have been implemented to shorten the computational time. The primary results are those modeling the discharge chamber of NASA's NSTAR ion engine at its full operating power. Convergence of numerical results such as total number of particles inside the discharge chamber, average energy of the plasma particles, discharge current, beam current and beam efficiency are obtained. Steady state results for

  15. Polar conic current sheets as sources and channels of energetic particles in the high-latitude heliosphere

    Science.gov (United States)

    Khabarova, Olga; Malova, Helmi; Kislov, Roman; Zelenyi, Lev; Obridko, Vladimir; Kharshiladze, Alexander; Tokumaru, Munetoshi; Sokół, Justyna; Grzedzielski, Stan; Fujiki, Ken'ichi; Malandraki, Olga

    2017-04-01

    The existence of a large-scale magnetically separated conic region inside the polar coronal hole has been predicted by the Fisk-Parker hybrid heliospheric magnetic field model in the modification of Burger and co-workers (Burger et al., ApJ, 2008). Recently, long-lived conic (or cylindrical) current sheets (CCSs) have been found from Ulysses observations at high heliolatitudes (Khabarova et al., ApJ, 2017). The characteristic scale of these structures is several times lesser than the typical width of coronal holes, and the CCSs can be observed at 2-3 AU for several months. CCS crossings in 1994 and 2007 are characterized by sharp decreases in the solar wind speed and plasma beta typical for predicted profiles of CCSs. In 2007, a CCS was detected directly over the South Pole and strongly highlighted by the interaction with comet McNaught. The finding is confirmed by restorations of solar coronal magnetic field lines that reveal the occurrence of conic-like magnetic separators over the solar poles both in 1994 and 2007. Interplanetary scintillation data analysis also confirms the existence of long-lived low-speed regions surrounded by the typical polar high-speed solar wind in solar minima. The occurrence of long-lived CCSs in the high-latitude solar wind could shed light on how energetic particles reach high latitudes. Energetic particle enhancements up to tens MeV were observed by Ulysses at edges of CCSs both in 1994 and 2007. In 1994 this effect was clearer, probably due to technical reasons. Accelerated particles could be produced either by magnetic reconnection at the edges of a CCS in the solar corona or in the solar wind. We discuss the role of high-latitude CCSs in propagation of energetic particles in the heliosphere and revisit previous studies of energetic particle enhancements at high heliolatitudes. We also suggest that the existence of a CCS can modify the distribution of the solar wind as a function of heliolatitude and consequently impact ionization

  16. Plasma polymerized allylamine coated quartz particles for humic acid removal.

    Science.gov (United States)

    Jarvis, Karyn L; Majewski, Peter

    2012-08-15

    Allylamine plasma polymerization has been used to modify the surface of quartz particles for humic acid removal via an inductively coupled rotating barrel plasma reactor. Plasma polymerized allylamine (ppAA) films were deposited at a power of 25 W, allylamine flow rate of 4.4 sccm and polymerization times of 5-60 min. The influence of polymerization time on surface chemistry was investigated via X-ray photoelectron spectroscopy (XPS), time of flight secondary ion mass spectrometry (ToF-SIMS) and electrokinetic analysis. Acid orange 7 adsorption/desorption quantified the number of surface amine groups. Humic acid removal via ppAA quartz particles was examined by varying pH, removal time, humic acid concentration, and particle mass. Increasing the polymerization time increased the concentration of amine groups on the ppAA quartz surface, thus also increasing the isoelectric point. ToF-SIMS demonstrated uniform distribution of amine groups across the particle surface. Greatest humic acid removal was observed at pH 5 due to electrostatic attraction. At higher pH values, for longer polymerization times, humic acid removal was also observed due to hydrogen bonding. Increasing the initial humic acid concentration increased the mass of humic acid removed, with longer polymerization times exhibiting the greatest increases. Plasma polymerization using a rotating plasma reactor has shown to be a successful method for modifying quartz particles for the removal of humic acid. Further development of the plasma polymerization process and investigation of additional contaminants will aid in the development of a low cost water treatment system.

  17. Microfabrication of through holes in polydimethylsiloxane (PDMS) sheets using a laser plasma EUV source (Conference Presentation)

    Science.gov (United States)

    Makimura, Tetsuya; Urai, Hikari; Niino, Hiroyuki

    2017-03-01

    Polydimethylsiloxane (PDMS) is a material used for cell culture substrates / bio-chips and micro total analysis systems / lab-on-chips due to its flexibility, chemical / thermo-dynamic stability, bio-compatibility, transparency and moldability. For further development, it is inevitable to develop a technique to fabricate precise three dimensional structures on micrometer-scale at high aspect ratio. In the previous works, we reported a technique for high-quality micromachining of PDMS without chemical modification, by means of photo direct machining using laser plasma EUV sources. In the present work, we have investigated fabrication of through holes. The EUV radiations around 10 nm were generated by irradiation of Ta targets with Nd:YAG laser light (10 ns, 500 mJ/pulse). The generated EUV radiations were focused using an ellipsoidal mirror. It has a narrower incident angle than those in the previous works in order to form a EUV beam with higher directivity, so that higher aspect structures can be fabricated. The focused EUV beam was incident on PDMS sheets with a thickness of 15 micrometers, through holes in a contact mask placed on top of them. Using a contact mask with holes with a diameter of three micrometers, complete through holes with a diameter of two micrometers are fabricated in the PDMS sheet. Using a contact mask with two micrometer holes, however, ablation holes almost reaches to the back side of the PDMS sheet. The fabricated structures can be explained in terms of geometrical optics. Thus, we have developed a technique for micromachining of PDMS sheets at high aspect ratios.

  18. Gyrokinetic Particle Simulation of Compressible Electromagnetic Turbulence in High-β Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zhihong

    2014-03-13

    Supported by this award, the PI and his research group at the University of California, Irvine (UCI) have carried out computational and theoretical studies of instability, turbulence, and transport in laboratory and space plasmas. Several massively parallel, gyrokinetic particle simulation codes have been developed to study electromagnetic turbulence in space and laboratory plasmas. In space plasma projects, the simulation codes have been successfully applied to study the spectral cascade and plasma heating in kinetic Alfven wave turbulence, the linear and nonlinear properties of compressible modes including mirror instability and drift compressional mode, and the stability of the current sheet instabilities with finite guide field in the context of collisionless magnetic reconnection. The research results have been published in 25 journal papers and presented at many national and international conferences. Reprints of publications, source codes, and other research-related information are also available to general public on the PI’s webpage (http://phoenix.ps.uci.edu/zlin/). Two PhD theses in space plasma physics are highlighted in this report.

  19. Review: engineering particles using the aerosol-through-plasma method

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Jonathan [Los Alamos National Laboratory; Luhrs, Claudia C [UNM; Richard, Monique [TEMA

    2009-01-01

    For decades, plasma processing of materials on the nanoscale has been an underlying enabling technology for many 'planar' technologies, particularly virtually every aspect of modern electronics from integrated-circuit fabrication with nanoscale elements to the newest generation of photovoltaics. However, it is only recent developments that suggest that plasma processing can be used to make 'particulate' structures of value in fields, including catalysis, drug delivery, imaging, higher energy density batteries, and other forms of energy storage. In this paper, the development of the science and technology of one class of plasma production of particulates, namely, aerosol-through-plasma (A-T-P), is reviewed. Various plasma systems, particularly RF and microwave, have been used to create nanoparticles of metals and ceramics, as well as supported metal catalysts. Gradually, the complexity of the nanoparticles, and concomitantly their potential value, has increased. First, unique two-layer particles were generated. These were postprocessed to create unique three-layer nanoscale particles. Also, the technique has been successfully employed to make other high-value materials, including carbon nanotubes, unsupported graphene, and spherical boron nitride. Some interesting plasma science has also emerged from efforts to characterize and map aerosol-containing plasmas. For example, it is clear that even a very low concentration of particles dramatically changes plasma characteristics. Some have also argued that the local-thermodynamic-equilibrium approach is inappropriate to these systems. Instead, it has been suggested that charged- and neutral-species models must be independently developed and allowed to 'interact' only in generation terms.

  20. Charged Particle Motion in a Highly Ionized Plasma

    CERN Document Server

    Brown, L S; Singleton, R; Brown, Lowell S; Preston, Dean L; Singleton, Robert L

    2005-01-01

    A recently introduced method utilizing dimensional continuation is employed to compute the energy loss rate for a non-relativistic particle moving through a highly ionized plasma. No restriction is made on the charge, mass, or speed of this particle. It is, however, assumed that the plasma is not strongly coupled in the sense that the dimensionless plasma coupling parameter g=e^2\\kappa_D/ 4\\pi T is small, where \\kappa_D is the Debye wave number of the plasma. To leading and next-to-leading order in this coupling, dE/dx is of the generic form g^2 \\ln[C g^2]. The precise numerical coefficient out in front of the logarithm is well known. We compute the constant C under the logarithm exactly for arbitrary particle speeds. Our exact results differ from approximations given in the literature. The differences are in the range of 20% for cases relevant to inertial confinement fusion experiments. The same method is also employed to compute the rate of momentum loss for a projectile moving in a plasma, and the rate at ...

  1. Dust Particle Dynamics in The Presence of Highly Magnetized Plasmas

    Science.gov (United States)

    Lynch, Brian; Konopka, Uwe; Thomas, Edward; Merlino, Robert; Rosenberg, Marlene

    2016-10-01

    Complex plasmas are four component plasmas that contain, in addition to the usual electrons, ions, and neutral atoms, macroscopic electrically charged (nanometer to micrometer) sized ``dust'' particles. These macroscopic particles typically obtain a net negative charge due to the higher mobility of electrons compared to that of ions. Because the electrons, ions, and dust particles are charged, their dynamics may be significantly modified by the presence of electric and magnetic fields. Possible consequences of this modification may be the charging rate and the equilibrium charge. For example, in the presence of a strong horizontal magnetic field (B >1 Tesla), it may be possible to observe dust particle gx B deflection and, from that deflection, determine the dust grain charge. In this poster, we present recent data from performing multiple particle dropping experiments to characterize the g x B deflection in the Magnetized Dusty Plasma Experiment (MDPX). This work is supported by funding from the U. S. Department of Energy Grant Number DE - SC0010485 and the NASA/Jet Propulsion Laboratory, JPL-1543114.

  2. Restructured graphene sheets embedded carbon film by oxygen plasma etching and its tribological properties

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Meiling [Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Diao, Dongfeng, E-mail: dfdiao@szu.edu.cn [Institute of Nanosurface Science and Engineering (INSE), Shenzhen University, Shenzhen 518060 (China); Yang, Lei [Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Fan, Xue [Institute of Nanosurface Science and Engineering (INSE), Shenzhen University, Shenzhen 518060 (China)

    2015-12-01

    Highlights: • Oxygen plasma etching was developed to improve tribological properties of GSEC film. • Etching restructured 3 nm top layer with smaller crystallite size and higher sp{sup 3} fraction. • The etched film had smoother surface, enhanced mechanical properties, longer wear life. • High electrical conductivity and strong magnetism were retained after etching. - Abstract: An oxygen plasma etching technique was introduced for improving the tribological properties of the graphene sheets embedded carbon (GSEC) film in electron cyclotron resonance plasma processing system. The nanostructural changing in the film caused by oxygen plasma etching was examined by transmission electron microscope, Raman spectroscopy and X-ray photoelectron spectroscopy, showing that the 3 nm thick top surface layer was restructured with smaller graphene nanocrystallite size as well as higher sp{sup 3} bond fraction. The surface roughness, mechanical behavior and tribological properties of the original GSEC and oxygen plasma treated GSEC films were compared. The results indicated that after the oxygen plasma treatment, the average roughness decreased from 20.8 ± 1.1 nm to 1.9 ± 0.1 nm, the hardness increased from 2.3 ± 0.1 GPa to 2.9 ± 0.1 GPa, the nanoscratch depth decreased from 64.5 ± 5.4 nm to 9.9 ± 0.9 nm, and the wear life increased from 930 ± 390 cycles to more than 15,000 frictional cycles. The origin of the improved tribological behavior was ascribed to the 3 nm thick graphene nanocrystallite film. This finding can be expected for wide applications in nanoscale surface engineering.

  3. Simulating Magnetized Laboratory Plasmas with Smoothed Particle Hydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Jeffrey N. [Univ. of California, Davis, CA (United States)

    2009-01-01

    The creation of plasmas in the laboratory continues to generate excitement in the physics community. Despite the best efforts of the intrepid plasma diagnostics community, the dynamics of these plasmas remains a difficult challenge to both the theorist and the experimentalist. This dissertation describes the simulation of strongly magnetized laboratory plasmas with Smoothed Particle Hydrodynamics (SPH), a method born of astrophysics but gaining broad support in the engineering community. We describe the mathematical formulation that best characterizes a strongly magnetized plasma under our circumstances of interest, and we review the SPH method and its application to astrophysical plasmas based on research by Phillips [1], Buerve [2], and Price and Monaghan [3]. Some modifications and extensions to this method are necessary to simulate terrestrial plasmas, such as a treatment of magnetic diffusion based on work by Brookshaw [4] and by Atluri [5]; we describe these changes as we turn our attention toward laboratory experiments. Test problems that verify the method are provided throughout the discussion. Finally, we apply our method to the compression of a magnetized plasma performed by the Compact Toroid Injection eXperiment (CTIX) [6] and show that the experimental results support our computed predictions.

  4. Porous poly(L-lactic acid) sheet prepared by stretching with starch particles as filler for tissue engineering.

    Science.gov (United States)

    Ju, Dandan; Han, Lijing; Li, Zonglin; Chen, Yunjing; Wang, Qingjiang; Bian, Junjia; Dong, Lisong

    2016-05-20

    Porous poly(L-lactic acid) (PLLA) sheets were prepared by uniaxial stretching PLLA sheets containing starch filler. Here, the starch filler content, stretching ratio, stretching rate and stretching temperature are important factors to influence the structure of the porous PLLA sheets, therefore, they have been investigated in detail. The pore size distribution and tortuosity were characterized by Mercury Intrusion Porosimetry. The results revealed that the porosity and pore size enlarged with the increase of the starch filler content and stretching ratio, while shrank with the rise of stretching temperature. On the other hand, the pore structure almost had no changes with the stretching rate ranging between 5 and 40 mm/min. In order to test and verify that the porous PLLA sheet was suitable for the tissue engineering, the starch particles were removed by selective enzymatic degradation and its in vitro biocompatibility to osteoblast-like MC3T3-E1 cells was investigated.

  5. Optimized H{sup -} extraction in an argon-magnesium seeded magnetized sheet plasma

    Energy Technology Data Exchange (ETDEWEB)

    Noguera, Virginia R. [Plasma Physics Laboratory, National Institute of Physics, University of the Philippines, Diliman, Quezon City 1101 (Philippines)], E-mail: virginia.noguera@gmail.com; Blantocas, Gene Q. [Plasma Physics Laboratory, National Institute of Physics, University of the Philippines, Diliman, Quezon City 1101 (Philippines); West Visayas State University, Lapaz, Iloilo City 5000 (Philippines); Ramos, Henry J. [Plasma Physics Laboratory, National Institute of Physics, University of the Philippines, Diliman, Quezon City 1101 (Philippines)

    2008-06-15

    The enhancement and optimization of H{sup -} extraction through argon and magnesium seeding of hydrogen discharges in a magnetized sheet plasma source are reported. The paper first presents the modification of the production chamber into a hexapole multicusp configuration resulting in decreased power requirements, improved plasma confinement and longer filament lifetime. By this, a wider choice of discharge currents for sustained quiescent plasmas is made possible. Second, the method of adding argon to the hydrogen plasma similar to the scheme in Abate and Ramos [Y. Abate, H. Ramos, Rev. Sci. Instr. 71 (10) (2000) 3689] was performed to find the optimum conditions for H{sup -} formation and extraction. Using an E x B probe, H{sup -} yields were investigated at varied argon-hydrogen admixtures, different discharge currents and spatial points relative to the core plasma. The optimum H{sup -} current density extracted at 3.0 cm from the plasma core using 3.0 A plasma current with 10% argon seeding increased by a factor of 2.42 (0.63 A/m{sup 2}) compared to the measurement of Abate and Ramos [Y. Abate, H. Ramos, Rev. Sci. Instr. 71 (10) (2000) 3689]. Third, the argon-hydrogen plasma at the extraction chamber is seeded with magnesium. Mg disk with an effective area of 22 cm{sup 2} is placed at the extraction region's anode biased 175 V with respect to the cathode. With Mg seeding, the optimum H{sup -} current density at the same site and discharge conditions increased by 4.9 times (3.09 A/m{sup 2}). The enhancement effects were analyzed vis-a-vis information gathered from the usual Langmuir probe (electron temperature and density), electron energy distribution function (EEDF) and the ensuing dissociative attachment (DA) reaction rates at different spatial points for various plasma discharges and gas ratios. Investigations on the changes in the effective electron temperature and electron density indicate that the enhancement is due to increased density of low

  6. Particle balance in long duration RF driven plasmas on QUEST

    Energy Technology Data Exchange (ETDEWEB)

    Hanada, K., E-mail: hanada@triam.kyushu-u.ac.jp [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 812-8580 (Japan); Zushi, H.; Yoshida, N. [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 812-8580 (Japan); Yugami, N.; Honda, T. [Interdisciplinary Graduate School of Engineering Science, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 816-8580 (Japan); Hasegawa, M. [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 812-8580 (Japan); Mishra, K. [Interdisciplinary Graduate School of Engineering Science, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 816-8580 (Japan); Kuzmin, A.; Nakamura, K.; Fujisawa, A.; Idei, H.; Nagashima, Y.; Watanabe, O.; Onchi, T.; Watanabe, H.; Tokunaga, K.; Higashijima, A.; Kawasaki, S.; Nakashima, H. [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 812-8580 (Japan); Takase, Y. [Graduate School of Frontier Science, University of Tokyo (Japan); and others

    2015-08-15

    Global particle balance in non-inductive long-duration plasma on QUEST has been investigated. Approximately 70% of the fuel hydrogen (H) was retained in the wall and then was almost exhausted just after the discharge. The global recycling ratio (R{sub g}), defined as the ratio of the evacuated H{sub 2} flux to that injected, was found to gradually increase during discharges and subsequently rose rapidly. To study the growth of R{sub g}, the thermal desorption spectra after deuterium implantation in a specimen exposed to QUEST plasma was analyzed with a model which includes reflection, diffusion, solution, recombination, trapping, and plasma-induced desorption in the re-deposition layer. The model reconstructs the growth of R{sub g} during a long-duration plasma and indicates solution plays a dominant role in the growth.

  7. Color-based tracking of plasma dust particles

    Energy Technology Data Exchange (ETDEWEB)

    Villamayor, Michelle Marie S., E-mail: mvillamayor@nip.upd.edu.ph; Soriano, Maricor N.; Ramos, Henry J. [National Institute of Physics, University of the Philippines, Diliman, Quezon City 1101 (Philippines); Kato, Shuichi; Wada, Motoi [Graduate School of Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321 (Japan)

    2014-02-15

    Color-based tracking to observe agglomeration of deposited particles inside a compact planar magnetron during plasma discharge was done by creating high dynamic range (HDR) images of photos captured by a Pentax K10D digital camera. Carbon erosion and redeposition was also monitored using the technique. The HDR images were subjected to a chromaticity-based constraint discoloration inside the plasma chamber indicating film formation or carbon redeposition. Results show that dust deposition occurs first near the evacuation pumps due to the pressure gradient and then accumulates at the positively charged walls of the chamber. This method can be applied to monitor dust formation during dusty plasma experiments without major modification of plasma devices, useful especially for large fusion reactors.

  8. Studying the Important Relationship Between Earth's Plasma Sheet and the Outer Radiation Belt Electrons Using Newly Calibrated and Corrected Themis-Sst Data

    Science.gov (United States)

    Cruce, P. R.; Turner, D. L.; Angelopoulos, V.; Larson, D. E.; Shprits, Y.; Huang, C.; Ukhorskiy, A. Y.

    2011-12-01

    Most recently, the solid-state telescope (SST) data from the THEMIS mission, which consisted of 5 spacecraft in highly elliptic, equatorial orbits that have traversed the outer radiation belt and sampled the plasma sheet for more than 4 years, have been characterized, calibrated, and decontaminated. Here, we present a brief introduction on this corrected dataset and go into detail on the valuable resource it provides to address science questions concerning the important relationship between ~1 keV-10's keV electrons in the plasma sheet and 100's keV-MeV electrons in Earth's outer radiation belt. We demonstrate this by presenting preliminary results on: studying phase space density (PSD) radial gradients for fixed first and second adiabatic invariants from the radiation belt into the plasma sheet, examining pitch angle distributions near the boundary between these two regions, and studying the boundary region itself around the last closed drift shell and the role of magnetopause shadowing losses. We examine the dependence of PSD radial gradients on the first and second invariants to test previous results [e.g., Turner et al., GRL, 2008; Kim et al., JGR, 2010] that reveal mostly positive radial gradients for lower energy electrons (10's - couple hundred keV) but negative gradients for relativistic electrons beyond geosynchronous orbit. This directly relates to the current theory that lower energy electrons have a source in the plasma sheet and are introduced to the ring current and radiation belt via substorm injections and enhanced convection, and these particles then generate the waves necessary to accelerate a fraction of this seed population to relativistic energies, providing a source of the outer radiation belt. Next, we take advantage of the pitch angle resolved differential energy fluxes to examine variations in pitch angle distributions to establish the role that Shabansky drift orbits, which break electrons' second adiabatic invariant, play on outer belt

  9. Modeling Plasma-Particle Interaction in Multi-Arc Plasma Spraying

    Science.gov (United States)

    Bobzin, K.; Öte, M.

    2017-01-01

    The properties of plasma-sprayed coatings are controlled by the heat, momentum, and mass transfer between individual particles and the plasma jet. The particle behavior in conventional single-arc plasma spraying has been the subject of intensive numerical research, whereas multi-arc plasma spraying has not yet received the same attention. We propose herein a numerical model to serve as a scientific tool to investigate particle behavior in multi-arc plasma spraying. In the Lagrangian description of particles in the model, the mathematical formulations describing the heat, momentum, and mass transfer are of great importance for good predictive power, so such formulations proposed by different authors were compared critically, revealing that different mathematical formulations lead to significantly different results. The accuracy of the different formulations was evaluated based on theoretical considerations, and those found to be more accurate were implemented in the final model. Furthermore, a mathematical formulation is proposed to enable simplified calculation of partial particle melting and resolidification.

  10. Influence of the initial parameters of the magnetic field and plasma on the spatial structure of the electric current and electron density in current sheets formed in helium

    Energy Technology Data Exchange (ETDEWEB)

    Ostrovskaya, G. V., E-mail: galya-ostr@mail.ru [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Markov, V. S.; Frank, A. G., E-mail: annfrank@fpl.gpi.ru [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2016-01-15

    The influence of the initial parameters of the magnetic field and plasma on the spatial structure of the electric current and electron density in current sheets formed in helium plasma in 2D and 3D magnetic configurations with X-type singular lines is studied by the methods of holographic interferometry and magnetic measurements. Significant differences in the structures of plasma and current sheets formed at close parameters of the initial plasma and similar configurations of the initial magnetic fields are revealed.

  11. ISEE-3 observations of a viscously-driven plasma sheet: magnetosheath mass and/or momentum transfer?

    Directory of Open Access Journals (Sweden)

    R. T. Mist

    Full Text Available A statistical analysis of data from the ISEE-3 distant tail campaign is presented. We investigate the mechanism driving slow, tailward flows observed in the plasma sheet. The possibility that these slow flows are driven by mass and/or momentum transfer across the distant tail magnetopause is explored. We establish that 40% of these flows could be driven by the transfer of approximately 4% of the magnetosheath momentum flux into the magnetotail. Current understanding of the Kelvin-Helmholtz instability suggests that this figure is consistent with the amount of momentum flux transfer produced by this mechanism. We also consider the possibility that these flows are solely driven by transferring magnetosheath plasma across the magnetopause. We find that there is sufficient mass observed on these field lines for this to be the sole driving mechanism for only 27% of the observed slow flows.

    Key words. Magnetospheric physics (magnetotail boundary layers; plasma convection; plasma sheet

  12. A computational model for He{sup +} ions in a magnetized sheet plasma: comparative analysis between model and experimental data

    Energy Technology Data Exchange (ETDEWEB)

    Blantocas, Gene Q. [West Visayas State Univ., Lapaz, Iloilo City (Philippines); Ramos, Henry J. [Univ. of the Phillippines, College of Science, National Inst. of Physics, Deliman Quezon City (Philippines); Wada, Motoi [Doshisha Univ., Dept. of Engineering, Kyoto (Japan)

    2003-07-01

    An E x B probe was used to extract He{sup +} ions from a magnetized steady sheet plasma. Plasma parameters T{sub e}, n{sub e} and extracted He{sup +} ion current were analyzed vis-a-vis a modified Saha population density equation of the collisional-radiative model. Numerical calculations show that at low discharge currents and in the hot electron region of the sheet plasma, relative densities of He{sup +} ions show some degree of correlation with ion current profiles established experimentally using the E x B probe. Both experimental and computational results indicate a division of the plasma into two distinct regions each with different formation mechanisms of He{sup +} ions. (author)

  13. Advanced Accelerators: Particle, Photon and Plasma Wave Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Ronald L. [Florida A & M University, Tallahassee, FL (United States)

    2017-06-29

    The overall objective of this project was to study the acceleration of electrons to very high energies over very short distances based on trapping slowly moving electrons in the fast moving potential wells of large amplitude plasma waves, which have relativistic phase velocities. These relativistic plasma waves, or wakefields, are the basis of table-top accelerators that have been shown to accelerate electrons to the same high energies as kilometer-length linear particle colliders operating using traditional decades-old acceleration techniques. The accelerating electrostatic fields of the relativistic plasma wave accelerators can be as large as GigaVolts/meter, and our goal was to study techniques for remotely measuring these large fields by injecting low energy probe electron beams across the plasma wave and measuring the beam’s deflection. Our method of study was via computer simulations, and these results suggested that the deflection of the probe electron beam was directly proportional to the amplitude of the plasma wave. This is the basis of a proposed diagnostic technique, and numerous studies were performed to determine the effects of changing the electron beam, plasma wave and laser beam parameters. Further simulation studies included copropagating laser beams with the relativistic plasma waves. New interesting results came out of these studies including the prediction that very small scale electron beam bunching occurs, and an anomalous line focusing of the electron beam occurs under certain conditions. These studies were summarized in the dissertation of a graduate student who obtained the Ph.D. in physics. This past research program has motivated ideas for further research to corroborate these results using particle-in-cell simulation tools which will help design a test-of-concept experiment in our laboratory and a scaled up version for testing at a major wakefield accelerator facility.

  14. Radial equilibrium of relativistic particle bunches in plasma wakefield accelerators

    CERN Document Server

    Lotov, K V

    2016-01-01

    Drive particle beams in linear or weakly nonlinear regimes of the plasma wakefield accelerator quickly reach a radial equilibrium with the wakefield, which is described in detail for the first time. The equilibrium beam state and self-consistent wakefields are obtained by combining analytical relationships, numerical integration, and first-principle simulations. In the equilibrium state, the beam density is strongly peaked near the axis, the beam radius is constant along the beam, and longitudinal variation of the focusing strength is balanced by varying beam emittance. The transverse momentum distribution of beam particles depends on the observation radius and is neither separable, nor Gaussian.

  15. Multigrid Particle-in-cell Simulations of Plasma Microturbulence

    Energy Technology Data Exchange (ETDEWEB)

    J.L.V. Lewandowski

    2003-06-17

    A new scheme to accurately retain kinetic electron effects in particle-in-cell (PIC) simulations for the case of electrostatic drift waves is presented. The splitting scheme, which is based on exact separation between adiabatic and on adiabatic electron responses, is shown to yield more accurate linear growth rates than the standard df scheme. The linear and nonlinear elliptic problems that arise in the splitting scheme are solved using a multi-grid solver. The multi-grid particle-in-cell approach offers an attractive path, both from the physics and numerical points of view, to simulate kinetic electron dynamics in global toroidal plasmas.

  16. Origin of low proton-to-electron temperature ratio in the Earth's plasma sheet

    Science.gov (United States)

    Grigorenko, E. E.; Kronberg, E. A.; Daly, P. W.; Ganushkina, N. Yu.; Lavraud, B.; Sauvaud, J.-A.; Zelenyi, L. M.

    2016-10-01

    We study the proton-to-electron temperature ratio (Tp/Te) in the plasma sheet (PS) of the Earth's magnetotail using 5 years of Cluster observations (2001-2005). The PS intervals are searched within a region defined with -19 GSM) under the condition |BX| ≤ 10 nT. One hundred sixty PS crossings are identified. We find an average value of 6.0. However, in many PS intervals Tp/Te varies over a wide range from a few units to several tens of units. In 86 PS intervals the Tp/Te decreases below 3.5. Generally, the decreases of Tp/Te are due to some increase of Te while Tp either decreases or remains unchanged. In the majority of these intervals the Tp/Te drops are observed during magnetotail dipolarizations. A superposed epoch analysis applied to these events shows that the minimum value of Tp/Te is observed after the dipolarization onset during the "turbulent phase" of dipolarization, when a number of transient BZ pulses are reduced, but the value of BZ is still large and an intensification of wave activity is observed. The Tp/Te drops, and associated increases of Te often coincide either with bursts of broadband electrostatic emissions, which may include electron cyclotron harmonics, or with broadband electromagnetic emission in a frequency range from proton plasma frequency (fpp) up to the electron gyrofrequency (fce). These findings show that the wave activity developing in the current sheet after dipolarization onset may play a role in the additional electron heating and the associated Tp/Te decrease.

  17. Collisionless shocks in space plasmas structure and accelerated particles

    CERN Document Server

    Burgess, David

    2015-01-01

    Shock waves are an important feature of solar system plasmas, from the solar corona out to the edge of the heliosphere. This engaging introduction to collisionless shocks in space plasmas presents a comprehensive review of the physics governing different types of shocks and processes of particle acceleration, from fundamental principles to current research. Motivated by observations of planetary bow shocks, interplanetary shocks and the solar wind termination shock, it emphasises the physical theory underlying these shock waves. Readers will develop an understanding of the complex interplay between particle dynamics and the electric and magnetic fields that explains the observations of in situ spacecraft. Written by renowned experts in the field, this up-to-date text is the ideal companion for both graduate students new to heliospheric physics and researchers in astrophysics who wish to apply the lessons of solar system shocks to different astrophysical environments.

  18. Particle Acceleration and Plasma Dynamics during Magnetic Reconnection in the Magnetically-dominated Regime

    CERN Document Server

    Guo, Fan; Daughton, William; Li, Hui

    2015-01-01

    Magnetic reconnection is thought to be the driver for many explosive phenomena in the universe. The energy release and particle acceleration during reconnection have been proposed as a mechanism for producing high-energy emissions and cosmic rays. We carry out two- and three-dimensional kinetic simulations to investigate relativistic magnetic reconnection and the associated particle acceleration. The simulations focus on electron-positron plasmas starting with a magnetically dominated, force-free current sheet ($\\sigma \\equiv B^2/(4\\pi n_e m_e c^2) \\gg 1$). For this limit, we demonstrate that relativistic reconnection is highly efficient at accelerating particles through a first-order Fermi process accomplished by the curvature drift of particles along the electric field induced by the relativistic flows. This mechanism gives rise to the formation of hard power-law spectra $f \\propto (\\gamma-1)^{-p}$ and approaches $p = 1$ for sufficiently large $\\sigma$ and system size. Eventually most of the available magne...

  19. Substorm effects on the plasma sheet on composition on March 22, 1979 (CDAW 6)

    Energy Technology Data Exchange (ETDEWEB)

    Lennartsson, W.; Sharp, R.D.; Zwickl, R.D.

    1985-02-01

    Data from the Plasma Composition Experiment on ISSE 1, covering the energy range 0.1--16 keV/e, show that a dramatic change took place in the plasma sheet ion composition in conjunction with the magnetic substorm activity on March 22, 1979. Beginning about 1124 UT the ion population at the ISEE 1 location changed from what appeared to be predominantly ions from the solar wind to a mixture of comparable numbers of solar wind and terrestrial ions. ISEE 1 was inbound in the predawn sector during this time, and the plasma composition experiment provided data from Rapprox. =21 R/sub E/ and LTapprox. =0130, down to Rapprox. =3 R/sub E/ and LTapprox. =0530. Prior to the substorm activity about 90--95% of the ion density was due to H/sup +/ and He/sup + +/ ions, which appeared to be mostly of solar wind origin. The H/sup +/ and He/sup + +/ components, each approximated by a Maxwell-Boltzmann distribution, had a temperature ratio T(He/sup + +/)/T(H/sup +/)approx. =4 and a density ratio n(He/sup + +/)/n(H/sup +/)approx. =1.5--3%. Both values are consistent with measurements made concurrently in the solar wind by the plasma experiment on ISSE 3. The remaining 5--10% of the density was due mainly to O/sup +/ and He/sup +/ ions of ionospheric origin. All four ion populations had broad energy spectra with mean energies of several keV/e.

  20. The evaluation of surface and adhesive bonding properties for cold rolled steel sheet for automotive treated by Ar/O{sub 2} atmospheric pressure plasma

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chan Joo; Lee, Sang Kon; Kim Byung Min [Pusan National University, Busan (Korea, Republic of); Park, Keun Whan [Sungwoo Hitech Technical Institute, Busan (Korea, Republic of)

    2008-04-15

    Cold rolled steel sheet for automotive was treated by Ar/O{sub 2} atmospheric pressure plasma to improve the adhesive bonding strength. Through the contact angle test and calculation of surface free energy for cold rolled steel sheet, the changes of surface properties were investigated before and after plasma treatment. The contact angle was decreased and surface free energy was increased after plasma treatment. And the change of surface roughness and morphology were observed by AFM(Atomic Force Microscope). The surface roughness of steel sheet was slightly changed. Based on Taguchi method, single lap shear test was performed to investigate the effect of experimental parameter such as plasma power, treatment time and flow rate of O{sub 2} gas. Results shows that the bonding strength of steel sheet treated in Ar/O{sub 2} atmospheric pressure plasma was improved about 20% compared with untreated sheet.

  1. Energetic particles in laboratory, space and astrophysical plasmas

    Science.gov (United States)

    McClements, K. G.; Turnyanskiy, M. R.

    2017-01-01

    Some recent studies of energetic particles in laboratory, space and astrophysical plasmas are discussed, and a number of common themes identified. Such comparative studies can elucidate the underlying physical processes. For example microwave bursts observed during edge localised modes (ELMs) in the mega amp spherical tokamak (MAST) can be attributed to energetic electrons accelerated by parallel electric fields associated with the ELMs. The very large numbers of electrons known to be accelerated in solar flares must also arise from parallel electric fields, and the demonstration of energetic electron production during ELMs suggests close links at the kinetic level between ELMs and flares. Energetic particle studies in solar flares have focussed largely on electrons rather than ions, since bremsstrahlung from deka-keV electrons provides the best available explanation of flare hard x-ray emission. However ion acceleration (but not electron acceleration) has been observed during merging startup of plasmas in MAST with dimensionless parameters similar to those of the solar corona during flares. Recent measurements in the Earth’s radiation belts demonstrate clearly a direct link between ion cyclotron emission (ICE) and fast particle population inversion, supporting the hypothesis that ICE in tokamaks is driven by fast particle distributions of this type. Shear Alfvén waves in plasmas with beta less than the electron to ion mass ratio have a parallel electric field that, in the solar corona, could accelerate electrons to hard x-ray-emitting energies; an extension of this calculation to plasmas with Alfvén speed arbitrarily close to the speed of light suggests that the mechanism could play a role in the production of cosmic ray electrons.

  2. Effective magnetization of the dust particles in a complex plasma

    Science.gov (United States)

    Kählert, Hanno

    2012-10-01

    The large mass and size of the dust particles in a complex plasma has several advantages, including low characteristic frequencies on the order of a few Hz and the ability to record their motion with video cameras. However, these properties pose major difficulties for achieving strong magnetization. While the light electrons and ions can be magnetized by (superconducting) magnets, magnetizing the heavy dust component is extremely challenging. Instead of further increasing the magnetic field strengths or decreasing the particle size, we use the analogy between the Lorentz force and the Coriolis force experienced by particles in a rotating reference frame to create ``effective magnetic fields'' which is a well-established technique in the field of trapped quantum gases [1]. To induce rotation in a complex plasma, we take advantage of the neutral drag force, which allows to transmit the motion of a rotating neutral gas to the dust particles [2]. The equations of motion in the rotating frame agree with those in a stationary gas except for the additional centrifugal and Coriolis forces [3]. Due to the slow rotation frequencies (˜ Hz) and contrary to the situation in a strong magnetic field, only the properties of the heavy dust particles are notably affected. Experiments with a rotating electrode realize the desired velocity profile for the neutral gas and allow us to verify the efficiency of the concept [3].[4pt] This work was performed in collaboration with J. Carstensen, M. Bonitz, H. L"owen, F. Greiner, and A. Piel.[4pt] [1] A. L. Fetter, Rev. Mod. Phys. 81, 647 (2009)[0pt] [2] J. Carstensen, F. Greiner, L.-J. Hou, H. Maurer, and A. Piel, Phys. Plasmas 16, 013702 (2009)[0pt] [3] H. K"ahlert, J. Carstensen, M. Bonitz, H. L"owen, F. Greiner, and A. Piel, submitted for publication, arXiv:1206.5073

  3. Plasmoid ejection and secondary current sheet generation from magnetic reconnection in laser-plasma interaction.

    Science.gov (United States)

    Dong, Quan-Li; Wang, Shou-Jun; Lu, Quan-Ming; Huang, Can; Yuan, Da-Wei; Liu, Xun; Lin, Xiao-Xuan; Li, Yu-Tong; Wei, Hui-Gang; Zhong, Jia-Yong; Shi, Jian-Rong; Jiang, Shao-En; Ding, Yong-Kun; Jiang, Bo-Bin; Du, Kai; He, Xian-Tu; Yu, M Y; Liu, C S; Wang, Shui; Tang, Yong-Jian; Zhu, Jian-Qiang; Zhao, Gang; Sheng, Zheng-Ming; Zhang, Jie

    2012-05-25

    Reconnection of the self-generated magnetic fields in laser-plasma interaction was first investigated experimentally by Nilson et al. [Phys. Rev. Lett. 97, 255001 (2006)] by shining two laser pulses a distance apart on a solid target layer. An elongated current sheet (CS) was observed in the plasma between the two laser spots. In order to more closely model magnetotail reconnection, here two side-by-side thin target layers, instead of a single one, are used. It is found that at one end of the elongated CS a fanlike electron outflow region including three well-collimated electron jets appears. The (>1 MeV) tail of the jet energy distribution exhibits a power-law scaling. The enhanced electron acceleration is attributed to the intense inductive electric field in the narrow electron dominated reconnection region, as well as additional acceleration as they are trapped inside the rapidly moving plasmoid formed in and ejected from the CS. The ejection also induces a secondary CS.

  4. CO2 laser-micro plasma arc hybrid welding for galvanized steel sheets

    Institute of Scientific and Technical Information of China (English)

    C. H. KIM; Y. N. AHN; J. H. KIM

    2011-01-01

    A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal. which is steel. In the autogenous laser welding,the zinc vapor generates from the lapped surfaces expels the molten pool and the expulsion causes numerous weld defects, such as spatters and blow holes on the weld surface and porosity inside the welds. The laser-arc hybrid welding was suggested as an alternative method for the laser lap welding because the arc can preheat or post-heat the weldment according to the arrangement of the laser beam and the arc. CO2 laser-micro plasma hybrid welding was applied to the lap welding of zinc-coated steel with zero-gap.The relationships among the weld quality and process parameters of the laser-arc arrangement, and the laser-arc interspacing distance and arc current were investigated using a full-factorial experimental design. The effect of laser-arc arrangement is dominant because the leading plasma arc partially melts the upper steel sheets and vaporizes or oxidizes the coated zinc on the lapped surfaces.Compared with the result from the laser-TIG hybrid welding, the heat input from arc can be reduced by 40%.

  5. Fractal Structure of the Heliospheric Plasma Sheet at the Earth's Orbit

    Institute of Scientific and Technical Information of China (English)

    M. V. Eselevich; V. G. Eselevich

    2005-01-01

    An analysis of the data from the Wind and IMP-8 spacecraft revealed that a slow solar wind,flowing in the heliospheric plasma sheet, represents a set of magnetic tubes with plasma of increased density(N > 10cm-3 at the Earth's orbit). They have a fine structure at several spatial scales (fractality), from2°-3° (at the Earth's orbit, it is equivalent to 3.6-5.4 h, or(5.4-8.0) × 106 km) to the minimum about0.025°, i.e. the angular siz.e of the nested tubes is changed nearly by two orders of magnitude. The magnetic tubes at each observed spatial scale are diamagnetic, i.e. their surface sustains a flow of diamagnetic (or drift)current that decreases the magnetic field within the tube itself and increases it outside the tube. Furthermore,the value of β = 8π[N(Te + Tp)]/B2 within the tube exceeds the value of β outside the tube. In many cases total pressure P = N(Te + Tp) + B2/8π is almost constant within and outside the tubes at any one of the aforementioned scales.

  6. Stellar cooling bounds on new light particles: including plasma effects

    CERN Document Server

    Hardy, Edward

    2016-01-01

    Strong constraints on the coupling of new light particles to the Standard Model (SM) arise from their production in the hot cores of stars, and the effects of this on stellar cooling. The large electron density in stellar cores significantly modifies the in-medium propagation of SM states. For new light particles which have an effective in-medium mixing with the photon, such plasma effects can result in parametrically different production rates to those obtained from a naive calculation. Taking these previously-neglected contributions into account, we make updated estimates for the stellar cooling bounds on a number of light new particle candidates. In particular, we improve the bounds on light (m < keV) scalars coupling to electrons or nucleons by up to 3 orders of magnitude in the coupling squared, significantly revise the supernova cooling bounds on dark photon couplings, and qualitatively change the mass dependence of stellar bounds on new vectors.

  7. Turbulent transport of alpha particles in tokamak plasmas

    Science.gov (United States)

    Croitoru, A.; Palade, D. I.; Vlad, M.; Spineanu, F.

    2017-03-01

    We investigate the \\boldsymbol{E}× \\boldsymbol{B} diffusion of fusion born α particles in tokamak plasmas. We determine the transport regimes for a realistic model that has the characteristics of the ion temperature gradient (ITG) or of the trapped electron mode (TEM) driven turbulence. It includes a spectrum of potential fluctuations that is modeled using the results of the numerical simulations, the drift of the potential with the effective diamagnetic velocity and the parallel motion. Our semi-analytical statistical approach is based on the decorrelation trajectory method (DTM), which is adapted to the gyrokinetic approximation. We obtain the transport coefficients as a function of the parameters of the turbulence and of the energy of the α particles. According to our results, significant turbulent transport of the α particles can appear only at energies of the order of 100 KeV. We determine the corresponding conditions.

  8. Many flaked particles generated by electric field stress working as an impulsive force in mass-production plasma etching equipment

    Science.gov (United States)

    Kasashima, Yuji; Uesugi, Fumihiko

    2015-09-01

    Particles generated in plasma etching significantly lower production yield. In plasma etching, etching reaction products adhere to the inner chamber walls, gradually forming films, and particles are generated by flaking of the deposited films due to electric field stress that acts boundary between the inner wall and the film. In this study, we have investigated the mechanism of instantaneous generation of many flaked particles using the mass-production reactive ion etching equipment. Particles, which flake off from the films on the ground electrode, are detected by the in-situ particle monitoring system using a sheet-shaped laser beam. The results indicate that the deposited films are severely damaged and flake off as numerous particles when the floating potential at the inner wall suddenly changes. This is because the rapid change in floating potential, observed when unusual wafer movement and micro-arc discharge occur, causes electric field stress working as an impulsive force. The films are easily detached by the impulsive force and many flaked particles are instantaneously generated. This mechanism can occur on not only a ground electrode but a chamber walls, and cause serious contamination in mass-production line. This work was partially supported by JSPS KAKENHI Grant Number B 26870903.

  9. Multiple harmonic ULF waves in the plasma sheet boundary layer: Instability analysis

    Science.gov (United States)

    Denton, R. E.; Engebretson, M. J.; Keiling, A.; Walsh, A. P.; Gary, S. P.; DéCréAu, P. M. E.; Cattell, C. A.; RèMe, H.

    2010-12-01

    Multiple-harmonic electromagnetic waves in the ULF band have occasionally been observed in Earth's magnetosphere, both near the magnetic equator in the outer plasmasphere and in the plasma sheet boundary layer (PSBL) in Earth's magnetotail. Observations by the Cluster spacecraft of multiple-harmonic electromagnetic waves with fundamental frequency near the local proton cyclotron frequency, Ωcp, were recently reported in the plasma sheet boundary layer by Broughton et al. (2008). A companion paper surveys the entire magnetotail passage of Cluster during 2003, and reports 35 such events, all in the PSBL, and all associated with elevated fluxes of counterstreaming ions and electrons. In this study we use observed pitch angle distributions of ions and electrons during a wave event observed by Cluster on 9 September 2003 to perform an instability analysis. We use a semiautomatic procedure for developing model distributions composed of bi-Maxwellian components that minimizes the difference between modeled and observed distribution functions. Analysis of wave instability using the WHAMP electromagnetic plasma wave dispersion code and these model distributions reveals an instability near Ωcp and its harmonics. The observed and model ion distributions exhibit both beam-like and ring-like features which might lead to instability. Further instability analysis with simple beam-like and ring-like model distribution functions indicates that the instability is due to the ring-like feature. Our analysis indicates that this instability persists over an enormous range in the effective ion beta (based on a best fit for the observed distribution function using a single Maxwellian distribution), β', but that the character of the instability changes with β'. For β' of order unity (for instance, the observed case with β' ˜ 0.4), the instability is predominantly electromagnetic; the fluctuating magnetic field has components in both the perpendicular and parallel directions, but the

  10. Ion shell distributions as free energy source for plasma waves on auroral field lines mapping to plasma sheet boundary layer

    Directory of Open Access Journals (Sweden)

    A. Olsson

    2004-06-01

    Full Text Available Ion shell distributions are hollow spherical shells in velocity space that can be formed by many processes and occur in several regions of geospace. They are interesting because they have free energy that can, in principle, be transmitted to ions and electrons. Recently, a technique has been developed to estimate the original free energy available in shell distributions from in-situ data, where some of the energy has already been lost (or consumed. We report a systematic survey of three years of data from the Polar satellite. We present an estimate of the free energy available from ion shell distributions on auroral field lines sampled by the Polar satellite below 6 RE geocentric radius. At these altitudes the type of ion shells that we are especially interested in is most common on auroral field lines close to the polar cap (i.e. field lines mapping to the plasma sheet boundary layer, PSBL. Our analysis shows that ion shell distributions that have lost some of their free energy are commonly found not only in the PSBL, but also on auroral field lines mapping to the boundary plasma sheet (BPS, especially in the evening sector auroral field lines. We suggest that the PSBL ion shell distributions are formed during the so-called Velocity Dispersed Ion Signatures (VDIS events. Furthermore, we find that the partly consumed shells often occur in association with enhanced wave activity and middle-energy electron anisotropies. The maximum downward ion energy flux associated with a shell distribution is often 10mWm-2 and sometimes exceeds 40mWm-2 when mapped to the ionosphere and thus may be enough to power many auroral processes. Earlier simulation studies have shown that ion shell distributions can excite ion Bernstein waves which, in turn, energise electrons in the parallel direction. It is possible that ion shell distributions are the link between the X-line and the auroral wave activity and electron

  11. Particle-in-Cell Codes for plasma-based particle acceleration

    CERN Document Server

    Pukhov, Alexander

    2016-01-01

    Basic principles of particle-in-cell (PIC ) codes with the main application for plasma-based acceleration are discussed. The ab initio full electromagnetic relativistic PIC codes provide the most reliable description of plasmas. Their properties are considered in detail. Representing the most fundamental model, the full PIC codes are computationally expensive. The plasma-based acceler- ation is a multi-scale problem with very disparate scales. The smallest scale is the laser or plasma wavelength (from one to hundred microns) and the largest scale is the acceleration distance (from a few centimeters to meters or even kilometers). The Lorentz-boost technique allows to reduce the scale disparity at the costs of complicating the simulations and causing unphysical numerical instabilities in the code. Another possibility is to use the quasi-static approxi- mation where the disparate scales are separated analytically.

  12. Controllable formation of graphene and graphene oxide sheets using photo-catalytic reduction and oxygen plasma treatment

    Science.gov (United States)

    Ostovari, Fatemeh; Abdi, Yaser; Ghasemi, Foad

    2012-12-01

    Au/SiO2/Si interdigital electrodes with thickness of 1 μm were created on silicon substrate. Graphene oxide (GO) sheets hanging from these electrodes were obtained by spin coating of chemically synthesized GO dispersed in water. We used UV-light-induced photo-catalytic activity of titanium oxide nanoparticles to reduce the GO layer. Effects of the photo-induced chemical reduction on the conductivity of the GO were investigated. Also, low power DC plasma was used for oxidation of the sheets. Oxygen bombardment leads to sheets with low electrical conductivity. Measurements show that graphene and GO sheets with the controlled electrical conductivity were obtained by these processes. Scanning electron and atomic force microscopy were used to study the morphology of the TiO2/GO and graphene structures. X-ray diffraction and Raman scattering analysis were used to verify the structural characteristics of the prepared sheets. Analysis showed a gradual increase in the number of C-O bonds on the surface of the graphene layer as a result of increasing the time of plasma bombardment. Based on the Raman spectroscopy, the photo-catalytic activity of TiO2 nanoparticles resulted in a decrease in the number of C-O bonds.

  13. New types of coating systems for steel sheets by high-rate evaporation in combination with plasma processes

    Energy Technology Data Exchange (ETDEWEB)

    Scheffel, B.; Metzner, C. [Fraunhofer-Institut fuer Elektronenstrahl und Plasmatechnik (FEP), Dresden (Germany); Ehlers, K.D. [Salzgitter AG Stahl und Technologie (Germany); Schuhmacher, B. [Dortmunder Oberflaechencentrum GmbH, Dortmund (Germany); Flossdorf, F.J.; Steinbeck, G. [Verein Deutscher Eisenhuettenleute (VDEh), Duesseldorf (Germany); Steffen, R. [Stahlwerke Bremen GmbH (Germany); Hagler, J. [voestalpine Stahl GmbH, Linz (Austria)

    2002-03-01

    High-rate evaporation in combination with plasma processes is a promising approach to obtain new types of steel sheet coating with improved corrosion resistance and application properties. To estimate the potential for the application of PVD-coatings (physical vapour deposition) different coating systems for steel sheet as well as for hot-dip or electro-galvanized steel sheet were designed. The samples were produced on a laboratory scale using PVD processes with very high deposition rates (in the order of 1 {mu}m s{sup -1}) as well as high-power plasma processes for the pre-treatment. The relationship between the composition, microstructure and properties of the coating systems, in particular concerning corrosion protection, abrasion during forming, phosphating and paint adhesion, were studied. It was found that the corrosion resistance of galvanized steel sheets can be considerably improved by vapour deposition of metal or inorganic films with a thickness of several hundred nanometers. Investigations on vapour deposition of titanium and stainless steel coatings on steel sheets, for applications in a severely corrosive environment, showed that the corrosion resistance in relation to the coating thickness can be significantly enhanced by means of plasma activation during the vapour deposition process. Finally, an outlook on possible industrial applications including an estimation of the process costs will be presented. For certain coating systems the results look promising. Consequently, these particular coating systems will be investigated in more detail by means of using a large-scale in-line deposition plant for metallic strips and sheets. (orig.)

  14. Versatile particle collection concept for correlation of particle growth and discharge parameters in dusty plasmas

    Science.gov (United States)

    Hinz, A. M.; von Wahl, E.; Faupel, F.; Strunskus, T.; Kersten, H.

    2015-02-01

    The feasibility of collecting nanoparticles from a dusty plasma by means of the neutral drag force is investigated. The nanoparticles are formed in a capacitively coupled asymmetric discharge running in an Ar/C2H2—mixture at a frequency of 13.56 MHz and an RF-power of 9 W. By opening a gate valve between the plasma reactor and a vacuum chamber at a lower pressure at any desired point of the growth cycle of the dust particles a neutral gas flux is induced that drags the particles out of the plasma onto a substrate. By changing the parameters of the collection process, e.g. the substrate positioning or the substrate temperature, the efficiency of the collection process can be adjusted. Information about the particle size distributions is obtained by performing ex situ SEM measurements. As the collection process creates a time stamp in the in situ recorded control parameters, e.g. the self-bias voltage or the process gas pressure, a direct and precise correlation between the control parameters and the particle size distribution is obtained.

  15. Parallel pic plasma simulation through particle decomposition techniques

    Energy Technology Data Exchange (ETDEWEB)

    Briguglio, S.; Vlad, G. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Energia; Di Martino, B. [Wien Univ. (Austria). Inst. for Software Tecnology and Parallel Systems]|[Naples, Univ. `Federico II` (Italy). Dipt. di Informatica e Sistemistica

    1998-02-01

    Particle-in-cell (PIC) codes are among the major candidates to yield a satisfactory description of the detail of kinetic effects, such as the resonant wave-particle interaction, relevant in determining the transport mechanism in magnetically confined plasmas. A significant improvement of the simulation performance of such codes con be expected from parallelization, e.g., by distributing the particle population among several parallel processors. Parallelization of a hybrid magnetohydrodynamic-gyrokinetic code has been accomplished within the High Performance Fortran (HPF) framework, and tested on the IBM SP2 parallel system, using a `particle decomposition` technique. The adopted technique requires a moderate effort in porting the code in parallel form and results in intrinsic load balancing and modest inter processor communication. The performance tests obtained confirm the hypothesis of high effectiveness of the strategy, if targeted towards moderately parallel architectures. Optimal use of resources is also discussed with reference to a specific physics problem. [Italiano] I codici Particle-in-cell (PIC) sono considerati tra i piu` promettenti candidati per ottenere una descrizione soddisfacente e dettagliata degli effetti cinetici, quali per esempio l`interazione risonante particella-onda, rilevanti nel determinare i meccanismi di trasporto che interessano il confinamento del plasma. Un significativo miglioramento delle prestazioni della simulazione puo` essere ottenuto distribuendo la popolazione di particelle tra diversi processori in parallelo. La parallelizzazione di un codice ibrido MHD-girocinetico e` stata effettuata, in ambiente HPF, utilizzando la tecnica di `decomposizione per particelle`, ed e` stata provata sul sistema parallelo IBM SP2. La tecnica adottata richiede uno sforzo moderato per la trasformazione del codice in versione parallela, permette un intrinseco bilanciamento tra i processori del carico di lavoro e necessita di una modesta

  16. Particle acceleration in cosmic plasmas – paradigm change?

    Energy Technology Data Exchange (ETDEWEB)

    Lytikov, Maxim [Purdue University; Guo, Fan [Los Alamos National Laboratory

    2015-07-21

    The presentation begins by considering the requirements on the acceleration mechanism. It is found that at least some particles in high-energy sources are accelerated by magnetic reconnection (and not by shocks). The two paradigms can be distinguished by the hardness of the spectra. Shocks typically produce spectra with p > 2 (relativistic shocks have p ~ 2.2); non-linear shocks & drift acceleration may give p < 2, e.g. p=1.5; B-field dissipation can give p = 1. Then collapse of stressed magnetic X-point in force-free plasma and collapse of a system of magnetic islands are taken up, including Island merger: forced reconnection. Spectra as functions of sigma are shown, and gamma ~ 109 is addressed. It is concluded that reconnection in magnetically-dominated plasma can proceed explosively, is an efficient means of particle acceleration, and is an important (perhaps dominant for some phenomena) mechanism of particle acceleration in high energy sources.

  17. Reconnection in the Heliosheath: Effects of Plasma Beta on Particle Acceleration and the Shape of Magnetic Islands

    Science.gov (United States)

    Schoeffler, K. M.; Drake, J. F.; Swisdak, M. M.

    2011-12-01

    In the heliosheath it has been predicted that current sheets are compressed and break up into magnetic islands or bubbles. The interaction of particles in these islands via the Fermi process in contracting islands has been predicted to be a source of anomalous cosmic rays (ACRs). The plasma β (the ratio of the plasma pressure to the magnetic pressure) can have a large range of values in this region. We investigate the effects of β on the formation of islands, and of the acceleration of particles as these magnetic islands form. Using a particle-in-cell code, we simulate island growth in multiple interacting Harris current sheets. We produce different values of β by changing the temperature of a background population. We find that for higher β significantly more elongated islands are formed. More modestly elongated islands are suppressed by pressure anisotropy approaching the marginal firehose condition. Measurements from the Voyager spacecrafts are consistent with these long islands. We also find significantly less electron acceleration as β increases, while the ions are mostly unaffected. Scattering of the electrons in high β systems (β > 1) halts the Fermi process while the ions continue to be accelerated.

  18. Particle model for nonlocal heat transport in fusion plasmas.

    Science.gov (United States)

    Bufferand, H; Ciraolo, G; Ghendrih, Ph; Lepri, S; Livi, R

    2013-02-01

    We present a simple stochastic, one-dimensional model for heat transfer in weakly collisional media as fusion plasmas. Energies of plasma particles are treated as lattice random variables interacting with a rate inversely proportional to their energy schematizing a screened Coulomb interaction. We consider both the equilibrium (microcanonical) and nonequilibrium case in which the system is in contact with heat baths at different temperatures. The model exhibits a characteristic length of thermalization that can be associated with an interaction mean free path and one observes a transition from ballistic to diffusive regime depending on the average energy of the system. A mean-field expression for heat flux is deduced from system heat transport properties. Finally, it is shown that the nonequilibrium steady state is characterized by long-range correlations.

  19. Modeling the Self-organized Critical Behavior of the Plasma Sheet Reconnection Dynamics

    Science.gov (United States)

    Klimas, Alex; Uritsky, Vadim; Baker, Daniel

    2006-01-01

    Analyses of Polar UVI auroral image data reviewed in our other presentation at this meeting (V. Uritsky, A. Klimas) show that bright night-side high-latitude UV emissions exhibit so many of the key properties of systems in self-organized criticality (SOC) that an alternate interpretation has become virtually impossible. It is now necessary to find and model the source of this behavior. We note that the most common models of self-organized criticality are numerical sandpiles. These are, at root, models that govern the transport of some quantity from a region where it is loaded to another where it is unloaded. Transport is enabled by the excitation of a local threshold instability; it is intermittent and bursty, and it exhibits a number of scale-free statistical properties. Searching for a system in the magnetosphere that is analogous and that, in addition, is known to produce auroral signatures, we focus on the reconnection dynamics of the plasma sheet. In our previous work, a driven reconnection model has been constructed and has been under study. The transport of electromagnetic (primarily magnetic) energy carried by the Poynting flux into the reconnection region of the model has been examined. All of the analysis techniques, and more, that have been applied to the auroral image data have also been applied to this Poynting flux. Here, we report new results showing that this model also exhibits so many of the key properties of systems in self-organized criticality that an alternate interpretation is implausible. Further, we find a strong correlation between these key properties of the model and those of the auroral UV emissions. We suggest that, in general, the driven reconnection model is an important step toward a realistic plasma physical model of self-organized criticality and we conclude, more specifically, that it is also a step in the right direction toward modeling the multiscale reconnection dynamics of the magnetotail.

  20. Modeling the Self-organized Critical Behavior of Earth's Plasma Sheet Reconnection Dynamics

    Science.gov (United States)

    Klimas, Alexander J.

    2006-01-01

    Analyses of Polar UVI auroral image data show that bright night-side high-latitude W emissions exhibit so many of the key properties of systems in self-organized criticality that an alternate interpretation has become virtually impossible. These analyses will be reviewed. It is now necessary to find and model the source of this behavior. We note that the most common models of self-organized criticality are numerical sandpiles. These are, at root, models that govern the transport of some quantity from a region where it is loaded to another where it is unloaded. Transport is enabled by the excitation of a local threshold instability; it is intermittent and bursty, and it exhibits a number of scale-free statistical properties. Searching for a system in the magnetosphere that is analogous and that, in addition, is known to produce auroral signatures, we focus on the reconnection dynamics of the magnetotail plasma sheet. In our previous work, a driven reconnection model has been constructed and has been under study. The transport of electromagnetic (primarily magnetic) energy carried by the Poynting flux into the reconnection region of the model has been examined. All of the analysis techniques (and more) that have been applied to the auroral image data have also been applied to this Poynting flux. New results will be presented showing that this model also exhibits so many of the key properties of systems in self-organized criticality that an alternate interpretation is implausible. A strong correlation between these key properties of the model and those of the auroral UV emissions will be demonstrated. We suggest that, in general, the driven reconnection model is an important step toward a realistic plasma physical model of self-organized criticality and we conclude, more specifically, that it is also a step in the right direction toward modeling the multiscale reconnection dynamics of the magnetotail.

  1. Shock wave interaction with a thermal layer produced by a plasma sheet actuator

    Science.gov (United States)

    Koroteeva, E.; Znamenskaya, I.; Orlov, D.; Sysoev, N.

    2017-03-01

    This paper explores the phenomena associated with pulsed discharge energy deposition in the near-surface gas layer in front of a shock wave from the flow control perspective. The energy is deposited in 200 ns by a high-current distributed sliding discharge of a ‘plasma sheet’ type. The discharge, covering an area of 100× 30 mm2, is mounted on the top or bottom wall of a shock tube channel. In order to analyse the time scales of the pulsed discharge effect on an unsteady supersonic flow, we consider the propagation of a planar shock wave along the discharge surface area 50–500 μs after the discharge pulse. The processes in the discharge chamber are visualized experimentally using the shadowgraph method and modelled numerically using 2D/3D CFD simulations. The interaction between the planar shock wave and the discharge-induced thermal layer results in the formation of a lambda-shock configuration and the generation of vorticity in the flow behind the shock front. We determine the amount and spatial distribution of the electric energy rapidly transforming into heat by comparing the calculated flow patterns and the experimental shadow images. It is shown that the uniformity of the discharge energy distribution strongly affects the resulting flow dynamics. Regions of turbulent mixing in the near-surface gas are detected when the discharge energy is deposited non-uniformly along the plasma sheet. They account for the increase in the cooling rate of the discharge-induced thermal layer and significantly influence its interaction with an incident shock wave.

  2. Modeling the effect of doping on the catalyst-assisted growth and field emission properties of plasma-grown graphene sheet

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Neha; Sharma, Suresh C.; Sharma, Rinku [Department of Applied Physics, Delhi Technological University (DTU), Shahbad Daulatpur, Bawana Road, Delhi-110042 (India)

    2016-08-15

    A theoretical model describing the effect of doping on the plasma-assisted catalytic growth of graphene sheet has been developed. The model accounts the charging rate of the graphene sheet, kinetics of all the plasma species, including the doping species, and the growth rate of graphene nuclei and graphene sheet due to surface diffusion, and accretion of ions on the catalyst nanoparticle. Using the model, it is observed that nitrogen and boron doping can strongly influence the growth and field emission properties of the graphene sheet. The results of the present investigation indicate that nitrogen doping results in reduced thickness and shortened height of the graphene sheet; however, boron doping increases the thickness and height of the graphene sheet. The time evolutions of the charge on the graphene sheet and hydrocarbon number density for nitrogen and boron doped graphene sheet have also been examined. The field emission properties of the graphene sheet have been proposed on the basis of the results obtained. It is concluded that nitrogen doped graphene sheet exhibits better field emission characteristics as compared to undoped and boron doped graphene sheet. The results of the present investigation are consistent with the existing experimental observations.

  3. A feature of negative hydrogen ion production in the Uramoto-type sheet plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jimbo, Kouichi [Kyoto Univ., Uji (Japan). Inst. of Atomic Energy

    1997-02-01

    It seems that negative hydrogen ions H{sup -} are formed directly from atomic hydrogens H. When the chamber was biased more negative against the anode potential at constant are power, forming a much deeper electrostatic well in the Uramoto-type sheet plasma negative ion source, more negative hydrogen ion currents were extracted. The chamber potential V{sub B} was biased down to -100V in the 150V discharge. The negative ion current J{sup -} was evaluated by the JAERI-probe measurement. J{sup -} increases linearly with the chamber current I{sub B}. The largest J{sup -} value was obtained at absolute value of |V{sub prob,f}|=15V and absolute value of |V{sub B}|=100V; the discharge was not operated for absolute value of |V{sub B}|>100V. We speculate the following collisional (three-body) electron attachment to H as a possible production process for H{sup -}; e+e+H{yields}e+H{sup -}. This process may explain the linear increase of J{sup -} with absolute value of |V{sub prob,f}|. (S.Y.)

  4. Study of kinetic Alfven wave (KAW) in plasma - sheet-boundary- layer

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, Nidhi; Varma, P; Tiwari, M S, E-mail: tiwarims@rediffmail.co, E-mail: poornimavarma@yahoo.co, E-mail: nidhiphy.shukla@gmail.co [Department of Physics and Electronics, Dr. H. S. Gour University, Sagar (M.P.), 470003 (India)

    2010-02-01

    The effect of parallel electric field with general loss-cone distribution function on the dispersion relation and damping rate/growth rate of the kinetic Alfven wave (KAW) is evaluated by kinetic approach. The generation of KAW by the combined effect of parallel electric field and loss-cone distribution indices (J) at a particular range of k{sub p}erpendicular{rho}{sub i} (k{sub p}erpendicular{rho}{sub i} <1 and k{sub p}erpendicular{rho}{sub i} >1) is noticed, where k{sub p}erpendicular is perpendicular wave number and {rho}{sub i} is the ion-gyro radius. Thus the propagation of KAW and loss of the Poynting flux from plasma sheet boundary layer (PSBL) to the ionosphere can be explained on the basis of present investigation. It is found that the present study also shows that the loss-cone distribution index is an important parameter to study KAW in the PSBL.

  5. Field-aligned currents observed by MMS in the near-Earth plasma sheet during large-scale substorm dipolarizations.

    Science.gov (United States)

    Nakamura, Rumi; Nagai, Tsugunobu; Giles, Barbara; Le Contel, Olivier; Stawarz, Julia; Khotyaintsev, Yuri; Artemyev, Anton

    2017-04-01

    During substorms significant energy conversion has been reported to take place at the sharp dipolarization front in the flow braking region where the probability of observing bursty bulk flows (BBFs) significantly drops. On 10 August 2016, MMS traversed the pre-midnight near-Earth plasma sheet when dipolarization disturbances were detected in an extended nightside local time region by Cluster, Geotail, GOES 13, 14 and 15, and the Van Allen Probes. In an expanding plasma sheet during the dipolarization, MMS detected sub-ion scale field-aligned current layers that are propagating both Earthward (equatorward) as well as tailward (outward). These multi-scale multi-point observations enable a unique investigation of both the meso-scale evolution of the disturbances and the detailed kinetic structures of the fronts and boundaries relevant to the dipolarizations.

  6. Smoothed Particle Hydrodynamics for the Simulation of Laser Produced Plasmas

    Science.gov (United States)

    Griffith, Alec; Holladay, Tyler; Murillo, Michael S.

    2016-10-01

    To address the design and interpretation of experiments at next generation light sources such as at the SLAC LCLS and the LANL proposed MaRIE a simulation of the laser produced plasma targets has been developed. Smoothed particle hydrodynamics is used to capture the full experimental time and length scales, large degrees of deformation, and the experimental environment's open boundary conditions. Additionally the model incorporates plasma transport with thermal conduction, the electric potential, and a two species model of the electrons and ions. The electron and ion particle representations in SPH allow for time dependent ionization and recombination while addressing the disparate masses of the two species. To gain computational speedup our simulation takes advantage of parallelism, and to reduce computational cost we have explored using data structures such as the linked cell list and octree as well as algorithmic techniques such as the fast mutipole method. We will discuss the results of simulating several possible experimental configurations using our model. This work was supported by the Los Alamos National Laboratory computational physics workshop.

  7. ISEE-3 observations of a viscously-driven plasma sheet: magnetosheath mass and/or momentum transfer?

    OpenAIRE

    Mist, R. T.; Owen, C.J.

    2002-01-01

    A statistical analysis of data from the ISEE-3 distant tail campaign is presented. We investigate the mechanism driving slow, tailward flows observed in the plasma sheet. The possibility that these slow flows are driven by mass and/or momentum transfer across the distant tail magnetopause is explored. We establish that 40% of these flows could be driven by the transfer of approximately 4% of the magnetosheath momentum flux into the magnetotail. Current understanding of the Kelvin-Helmholtz in...

  8. ISEE-3 observations of a viscously-driven plasma sheet: magnetosheath mass and/or momentum transfer?

    OpenAIRE

    Mist, R. T.; Owen, C.J.

    2002-01-01

    A statistical analysis of data from the ISEE-3 distant tail campaign is presented. We investigate the mechanism driving slow, tailward flows observed in the plasma sheet. The possibility that these slow flows are driven by mass and/or momentum transfer across the distant tail magnetopause is explored. We establish that 40% of these flows could be driven by the transfer of approximately 4% of the magnetosheath momentum flux into the magnetotail. Current understanding of the Kelvin-Helmh...

  9. Small-scale magnetic islands in the solar wind and their role in particle acceleration. Part 1: Dynamics of magnetic islands near the heliospheric current sheet

    CERN Document Server

    Khabarova, O; Li, G; Roux, J A le; Webb, G M; Dosch, A; Malandraki, O E

    2015-01-01

    Increases of ion fluxes in the keV-MeV range are sometimes observed near the heliospheric current sheet (HCS) during periods when other sources are absent. These resemble solar energetic particle (SEP) events, but the events are weaker and apparently local. Conventional explanations based on either shock acceleration of charged particles or particle acceleration due to magnetic reconnection at interplanetary current sheets are not persuasive. We suggest instead that recurrent magnetic reconnection occurs at the HCS and smaller current sheets in the solar wind (Zharkova & Khabarova 2012), of which a consequence is particle energization by the dynamically evolving secondary current sheets and magnetic islands (Zank et al. 2014; Drake et al. 2006a). The effectiveness of the trapping and acceleration process associated with magnetic islands depends in part on the topology of the HCS. We show that the HCS possesses ripples superimposed on the large-scale flat or wavy structure. We conjecture that the ripples c...

  10. Plasma arc brazing - a low energy joining technology for steel sheets; Plasmalichtbogenloeten - eine energiearme Fuegetechnik fuer Feinblechwerkstoffe

    Energy Technology Data Exchange (ETDEWEB)

    Bouaifi, B.; Draugelates, U.; Helmich, A.; Ouaissa, B. [TU Clausthal, Clausthal-Zellerfeld (Germany)

    2001-07-01

    Mild and high strength steel sheets are comparatively difficult to weld. The heat input in the case of conventional welding processes is too high, so that plasma brazing is an attractive alternative and complementary joining process. One characteristic of the process is the independent input of energy and filler material. In addition, the process is practically spatter-free. Plasma brazing reduces joint and panel distortion and is tolerant to surface contamination and metallic surface coatings. The brazed seams are aesthetic in appearance and clear good mechanical properties. (orig.)

  11. Particle Acceleration and Plasma Heating in the Chromosphere

    Science.gov (United States)

    Zaitsev, V. V.; Stepanov, A. V.

    2015-12-01

    We propose a new mechanism of electron acceleration and plasma heating in the solar chromosphere, based on the magnetic Rayleigh-Taylor instability. The instability develops at the chromospheric footpoints of a flare loop and deforms the local magnetic field. As a result, the electric current in the loop varies, and a resulting inductive electric field appears. A pulse of the induced electric field, together with the pulse of the electric current, propagates along the loop with the Alfvén velocity and begins to accelerate electrons up to an energy of about 1 MeV. Accelerated particles are thermalized in the dense layers of the chromosphere with the plasma density n ≈10^{14} - 10^{15} cm^{-3}, heating them to a temperature of about several million degrees. Joule dissipation of the electric current pulse heats the chromosphere at heights that correspond to densities n ≤10^{11} - 10^{13} cm^{-3}. Observations with the New Solar Telescope at Big Bear Solar Observatory indicate that chromospheric footpoints of coronal loops might be heated to coronal temperatures and that hot plasma might be injected upwards, which brightens ultra-fine loops from the photosphere to the base of the corona. Thereby, recent observations of the Sun and the model we propose stimulate a déjà vu - they are reminiscent of the concept of the chromospheric flare.

  12. Element Abundances and Source Plasma Temperatures of Solar Energetic Particles

    Science.gov (United States)

    Reames, Donald V.

    2016-11-01

    Thirty years ago Breneman and Stone [1] observed that the enhancement or suppression of element abundances in large solar energetic-particle (SEP) events varies as a power of the mass-to-charge ratio, A/Q, of the elements. Since Q during acceleration or transport may depend upon the source plasma temperature T, the pattern of element enhancements can provide a best-fit measure of T. The small SEP events we call 3He-rich or “impulsive” show average enhancements, relative to coronal abundances, rising as the 3.6 power of A/Q to a factor of ∼1000 for (76magnetic reconnection on open field lines in solar flares and jets. It has been recently found that the large shock-accelerated “gradual” SEP events have a broad range of source plasma temperatures; 69% have coronal temperatures of T seed population containing residual impulsive suprathermal ions. Most of the large event-to-event abundance variations and their time variation are largely explained by variations in T magnified by A/Q-dependent fractionation during transport. However, the non-thermal variance of impulsive SEP events (∼30%) exceeds that of the ∼3 MK gradual events (∼10%) so that several small impulsive events must be averaged together with the ambient plasma to form the seed population for shock acceleration in these events.

  13. Freak waves in a plasma having Cairns particles

    Science.gov (United States)

    El-Tantawy, S. A.; El-Awady, E. I.; Schlickeiser, R.

    2015-12-01

    The probability of the existence of the ion-acoustic rogue waves in a plasma composed of warm ions and non-Maxwellian (nonthermal or Kappa) electrons is investigated in the framework of the modified Korteweg-de Vries (mKdV) equation. Using the reductive perturbation method, the Korteweg-de Vries (KdV) equation is derived. After numerical analysis, it is found that the present plasma system populated with nonthermal (Cairns) electrons leads to generation of compressive and rarefactive pulses, in contrast to the case of Kappa distribution. Thus, only for the nonthermal populated electrons, there is a critical value of the nonthermal parameter at which the coefficient of the nonlinear term of the KdV equation vanishes. In this case, we derived the modified KdV (mKdV) equation to describe the evolution of the system. To investigate the rogue waves propagation in our system, the mKdV equation should transfer to the nonlinear Schrödinger equation (NLSE). Our results provide a better understanding of observations in space plasmas which indicate the existence of nonthermal particles.

  14. Dependence of sheet resistance on dispersion of multi-walled carbon nanotubes grown using size-controlled catalyst particles

    Energy Technology Data Exchange (ETDEWEB)

    Park, Suyoung [Helmut-Fischer Korea, 462, Dogok-ro, Songpa-gu, Seoul 05574 (Korea, Republic of); Kim, Youngkwang [R& D Center, VATECH, 13, Samsung 1-ro 2-gil, Hwaseong-si, Gyeonggi-do 445-170 (Korea, Republic of); Kim, Minhwan [Helmut-Fischer Korea, 462, Dogok-ro, Songpa-gu, Seoul 05574 (Korea, Republic of); Lee, Dongjin [School of Mechanical Engineering, Konkuk University, Seoul 143-701 (Korea, Republic of); Flexible Display Roll-to-Roll Research Center, Konkuk University, Seoul 143-701 (Korea, Republic of); Jin, Changhyun, E-mail: jinch@konkuk.ac.kr [School of Mechanical Engineering, Konkuk University, Seoul 143-701 (Korea, Republic of)

    2015-11-15

    Graphical abstract: Nucleation and growth of MWCNTs obtained from different catalyst size. - Highlights: • Catalyst-assisted MWCNT networks were successfully synthesized. • The MWCNT sizes varied according to initial catalyst particle sizes. • The MWCNT sheet resistance values were estimated with a four-point probe. - Abstract: Catalyst-assisted synthesis of multi-walled carbon nanotube (MWCNT) networks was successfully realized by controlling the catalyst particle size with and without post annealing. The sizes of ternary composite catalyst synthesized from spray pyrolysis method varied with different partial pressures and post-annealing. Various-sized MWCNT networks corresponding to individual catalyst sizes were produced through chemical vapor deposition technique. To investigate the dispersion of MWCNTs with respect to catalyst particle size, particle size analyses, scanning electron microscopy, and transmission electron microscopy were performed. In addition, the sieve shaker with 250 mesh were also used for evaluation of correlation between the MWCNTs networks and catalyst sizes. For electrical properties of the samples, MWCNT sheet resistance values were estimated with a four-point probe. These values were used to establish the optimal dispersion of MWCNTs needed to yield optimal carrier density and mobility.

  15. Particle heating and acceleration during collisionless reconnection in a laboratory plasma

    Science.gov (United States)

    Yoo, Jongsoo

    2013-10-01

    Particle heating and acceleration during magnetic reconnection is studied in the collisionless plasma of the Magnetic Reconnection Experiment (MRX). For ion heating and acceleration, the role of the in-plane (Hall) electric field is emphasized. An in-plane electrostatic potential profile is established by electron acceleration near the X-point. The potential profile shows a well structure along the direction normal to the reconnection current sheet that becomes deeper and wider downstream as its boundary expands along the separatrices where the in-plane electric field is strongest. The Hall electric field ballistically accelerates ions near the separatrices toward the outflow direction. After ions are accelerated, they are heated as they travel into the high-pressure downstream region due to an effect called re-magnetization. Electrons are also significantly heated during reconnection. The electron temperature sharply increases across the separatrices and peaks just outside of the electron diffusion region. Classical Ohmic dissipation based on the perpendicular Spitzer resistivity is too small to compensate for the energy loss by parallel heat conduction, indicating the presence of anomalous electron heating. Finally, a total energy inventory is calculated based on analysis of the Poynting, enthalpy, flow energy, and heat flux in the measured diffusion layer. More than half of the incoming magnetic energy is converted to particle energy during reconnection. The author thanks contributions from M. Yamada, H. Ji, J. Jara-Almonte, and C. E. Myers. This work is supported by DOE and NSF.

  16. Bulk ion acceleration and particle heating during magnetic reconnection in a laboratory plasma

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jongsoo; Yamada, Masaaki; Ji, Hantao; Jara-Almonte, Jonathan; Myers, Clayton E. [Center for Magnetic Self-Organization, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2014-05-15

    Bulk ion acceleration and particle heating during magnetic reconnection are studied in the collisionless plasma of the Magnetic Reconnection Experiment (MRX). The plasma is in the two-fluid regime, where the motion of the ions is decoupled from that of the electrons within the ion diffusion region. The reconnection process studied here is quasi-symmetric since plasma parameters such as the magnitude of the reconnecting magnetic field, the plasma density, and temperature are compatible on each side of the current sheet. Our experimental data show that the in-plane (Hall) electric field plays a key role in ion heating and acceleration. The electrostatic potential that produces the in-plane electric field is established by electrons that are accelerated near the electron diffusion region. The in-plane profile of this electrostatic potential shows a “well” structure along the direction normal to the reconnection current sheet. This well becomes deeper and wider downstream as its boundary expands along the separatrices where the in-plane electric field is strongest. Since the in-plane electric field is 3–4 times larger than the out-of-plane reconnection electric field, it is the primary source of energy for the unmagnetized ions. With regard to ion acceleration, the Hall electric field causes ions near separatrices to be ballistically accelerated toward the outflow direction. Ion heating occurs as the accelerated ions travel into the high pressure downstream region. This downstream ion heating cannot be explained by classical, unmagnetized transport theory; instead, we conclude that ions are heated by re-magnetization of ions in the reconnection exhaust and collisions. Two-dimensional (2-D) simulations with the global geometry similar to MRX demonstrate downstream ion thermalization by the above mechanisms. Electrons are also significantly heated during reconnection. The electron temperature sharply increases across the separatrices and peaks just outside of the

  17. Charge dependence of nano-particle growth in silane plasmas under UV irradiation

    Science.gov (United States)

    Seon, C. R.; Choe, W.; Chai, K. B.; Park, H. Y.; Park, S.

    2009-01-01

    The controlled generation of nano-particles has been an important issue for the nano-structure formation in processing plasmas. We observed that the particle growth under UV irradiation was enhanced due to electric charge reduction of the particles, suggesting that the variation of particle charges could be a control parameter for the particle growth. The particle growth variation by UV irradiation is well described by the particle coagulation model with time-dependent particle charges in consideration, where predator particles grow by adsorbing a few nanometer-sized proto-particles.

  18. Energetic electron bursts in the plasma sheet and their relation with BBFs

    Science.gov (United States)

    Duan, A. Y.; Cao, J. B.; Dunlop, M.; Wang, Z. Q.

    2014-11-01

    We studied energetic electron bursts (EEBs) (40-250 keV) in the plasma sheet (PS) and their relation to bursty bulk flows (BBFs) using the data recorded by Cluster from 2001 to 2009. The EEBs in the PS can be classified into four types. Three types of EEBs are dispersionless, including EEBs accompanied with BBFs (V > 250 km/s) but without dipolarization front (DF); EEBs accompanied with both dipolarization front (DF) and BBF; and EEBs accompanied with DF and fast flow with V EEB, i.e., EEBs not accompanied with BBFs and DFs, is dispersed. The energetic electrons (40-130 keV) can be easily transported earthward by BBFs due to the strong dawn-dusk electric field embedded in BBFs. The DFs in BBFs can produce energetic electrons (40 to 250 keV). For the EEBs with DF and BBFs, the superposed epoch analyses show that the increase of energetic electron flux has two phases: gradual increase phase before DF and rapid increase phase concurrent with DF. In the PS around x = -18 RE, 60%-70% of EEBs are accompanied with BBFs, indicating that although hitherto there have been various acceleration mechanisms of energetic electrons, most of the energetic electrons in the PS are related with magnetic reconnection, and they are produced either directly by magnetic reconnection or indirectly by the DFs within BBFs. In the BBF's braking region of -12 RE EEBs are accompanied with BBFs. The corresponding ratio between EEBs and BBFs shows a dawn-dusk asymmetry.

  19. Characteristics of Wave-Particle Interaction in a Hydrogen Plasma

    Institute of Scientific and Technical Information of China (English)

    HE Hui-Yong; CHEN Liang-Xu; LI Jiang-Fan

    2008-01-01

    We study the characteristics of cyclotron wave-particle interaction in a typical hydrogen plasma. The numerical calculations of minimum resonant energy Emin, resonant wave frequency w, and pitch angle diffusion coefficient Dαα for interactions between R-mode/L-mode and electrons/protons are presented. It is found that Emin decreases with ω for R-mode/electron, L-mode/proton and L-mode/electron interactions, but increase with w for R-mode/proton interaction. It is shown that both R-mode and L-mode waves can efficiently scatter energetic (10 keV~100 keV) electrons and protons and cause precipitation loss at L=4, indicating that perhaps waveparticle interaction is a serious candidate for the ring current decay.

  20. Experimental study of nonlinear interaction of plasma flow with charged thin current sheets: 2. Hall dynamics, mass and momentum transfer

    Directory of Open Access Journals (Sweden)

    S. Savin

    2006-01-01

    Full Text Available Proceeding with the analysis of Amata et al. (2005, we suggest that the general feature for the local transport at a thin magnetopause (MP consists of the penetration of ions from the magnetosheath with gyroradius larger than the MP width, and that, in crossing it, the transverse potential difference at the thin current sheet (TCS is acquired by these ions, providing a field-particle energy exchange without parallel electric fields. It is suggested that a part of the surface charge is self-consistently produced by deflection of ions in the course of inertial drift in the non-uniform electric field at MP. Consideration of the partial moments of ions with different energies demonstrates that the protons having gyroradii of roughly the same size or larger than the MP width carry fluxes normal to MP that are about 20% of the total flow in the plasma jet under MP. This is close to the excess of the ion transverse velocity over the cross-field drift speed in the plasma flow just inside MP (Amata et al., 2005, which conforms to the contribution of the finite-gyroradius inflow across MP. A linkage through the TCS between different plasmas results from the momentum conservation of the higher-energy ions. If the finite-gyroradius penetration occurs along the MP over ~1.5 RE from the observation site, then it can completely account for the formation of the jet under the MP. To provide the downstream acceleration of the flow near the MP via the cross-field drift, the weak magnetic field is suggested to rotate from its nearly parallel direction to the unperturbed flow toward being almost perpendicular to the accelerated flow near the MP. We discuss a deceleration of the higher-energy ions in the MP normal direction due to the interaction with finite-scale electric field bursts in the magnetosheath flow frame, equivalent to collisions, providing a charge separation. These effective collisions, with a nonlinear frequency proxy of the order of the proton

  1. Effect of dust particle polarization on scattering processes in complex plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kodanova, S. K.; Ramazanov, T. S.; Bastykova, N. Kh.; Moldabekov, Zh. A. [Institute for Experimental and Theoretical Physics, Al-Farabi Kazakh National University, 71 Al-Farabi Str., 050040 Almaty (Kazakhstan)

    2015-06-15

    Screened interaction potentials in dusty plasmas taking into account the polarization of dust particles have been obtained. On the basis of screened potentials scattering processes for ion-dust particle and dust particle-dust particle pairs have been studied. In particular, the scattering cross section is considered. The scattering processes for which the dust grain polarization is unimportant have been found. The effect of zero angle dust particle-dust particle scattering is predicted.

  2. Element Abundances and Source Plasma Temperatures of Solar Energetic Particles

    CERN Document Server

    Reames, Donald V

    2016-01-01

    Thirty years ago Breneman and Stone observed that the enhancement or suppression of element abundances in large solar energetic-particle (SEP) events varies as a power of the mass-to-charge ratio, A/Q, of the elements. Since Q during acceleration or transport may depend upon the source plasma temperature T, the pattern of element enhancements can provide a best-fit measure of T. The small SEP events we call 3He-rich or "impulsive" show average enhancements, relative to coronal abundances, rising as the 3.6 power of A/Q to a factor of ~1000 for (76<=Z<=82)/O and temperature in the range 2-4 MK. This acceleration is believed to occur in islands of magnetic reconnection on open field lines in solar flares and jets. It has been recently found that the large shock-accelerated "gradual" SEP events have a broad range of source plasma temperatures; 69% have coronal temperatures of T < 1.6 MK, while 24% have T ~ 3 MK, the latter suggesting a seed population containing residual impulsive suprathermal ions. Mos...

  3. Phase Transitions in a Dusty Plasma with Two Distinct Particle Sizes

    CERN Document Server

    Smith, B; Matthews, L; Reay, J; Cook, M; Schmoke, J

    2005-01-01

    In semiconductor manufacturing, contamination due to particulates significantly decreases the yield and quality of device fabrication, therefore increasing the cost of production. Dust particle clouds can be found in almost all plasma processing environments including both plasma etching devices and in plasma deposition processes. Dust particles suspended within such plasmas will acquire an electric charge from collisions with free electrons in the plasma. If the ratio of inter-particle potential energy to the average kinetic energy is sufficient, the particles will form either a liquid structure with short range ordering or a crystalline structure with long range ordering. Otherwise, the dust particle system will remain in a gaseous state. Many experiments have been conducted over the past decade on such colloidal plasmas to discover the character of the systems formed, but more work is needed to fully understand these structures. The preponderance of previous experiments used monodisperse spheres to form co...

  4. Role of magnetic field fluctuations in the Evolution of the kappa Distribution Functions in the Plasma Sheet

    Science.gov (United States)

    Espinoza, Cristobal; Antonova, Elizaveta; Stepanova, Marina; Valdivia, Juan Alejandro

    2016-07-01

    The evolution with the distance to Earth of ion and electron distribution functions in the plasma sheet, approximated by kappa distributions, was studied by Stepanova and Antonova (2015, JGRA 120). Using THEMIS data for 5 events of satellite alignments along the tail, covering between 5 and 30 Earth radii, they found that the kappa parameter increases tailwards, for both ions and electrons. In this work we analyse the magnetic fluctuations present in THEMIS data for the same 5 events. The aim is to explore the hypothesis proposed by Navarro et al. (2014, PRL 112), for solar wind plasmas, that the observed magnetic fluctuations could be closely related to spontaneous fluctuations in the plasma, if this can be described by stable distributions. Here we present our first results on the correlation between the spectral properties of the magnetic fluctuations and the observed parameters of the kappa distributions for different distances from Earth.

  5. Density Dependence of Particle Transport in ECH Plasmas of the TJ-II Stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, V. I.; Lopez-Bruna, D.; Guasp, J.; Herranz, J.; Estrada, T.; Medina, F.; Ochando, M.A.; Velasco, J.L.; Reynolds, J.M.; Ferreira, J.A.; Tafalla, D.; Castejon, F.; Salas, A.

    2009-05-21

    We present the experimental dependence of particle transport on average density in electron cyclotron heated (ECH) hydrogen plasmas of the TJ-II stellarator. The results are based on: (I) electron density and temperature data from Thomson Scattering and reflectometry diagnostics; (II) a transport model that reproduces the particle density profiles in steady state; and (III) Eirene, a code for neutrals transport that calculates the particle source in the plasma from the particle confinement time and the appropriate geometry of the machine/plasma. After estimating an effective particle diffusivity and the particle confinement time, a threshold density separating qualitatively and quantitatively different plasma transport regimes is found. The poor confinement times found below the threshold are coincident with the presence of ECH-induced fast electron losses and a positive radial electric field all over the plasma. (Author) 40 refs.

  6. Multi-Objective Parallel Test-Sheet Composition Using Enhanced Particle Swarm Optimization

    Science.gov (United States)

    Ho, Tsu-Feng; Yin, Peng-Yeng; Hwang, Gwo-Jen; Shyu, Shyong Jian; Yean, Ya-Nan

    2009-01-01

    For large-scale tests, such as certification tests or entrance examinations, the composed test sheets must meet multiple assessment criteria. Furthermore, to fairly compare the knowledge levels of the persons who receive tests at different times owing to the insufficiency of available examination halls or the occurrence of certain unexpected…

  7. Low sheet resistance titanium nitride films by low-temperature plasma-enhanced atomic layer deposition using design of experiments methodology

    Energy Technology Data Exchange (ETDEWEB)

    Burke, Micheal, E-mail: micheal.burke@tyndall.ie; Blake, Alan; Povey, Ian M.; Schmidt, Michael; Petkov, Nikolay; Carolan, Patrick; Quinn, Aidan J., E-mail: aidan.quinn@tyndall.ie [Tyndall National Institute, University College Cork, Cork (Ireland)

    2014-05-15

    A design of experiments methodology was used to optimize the sheet resistance of titanium nitride (TiN) films produced by plasma-enhanced atomic layer deposition (PE-ALD) using a tetrakis(dimethylamino)titanium precursor in a N{sub 2}/H{sub 2} plasma at low temperature (250 °C). At fixed chamber pressure (300 mTorr) and plasma power (300 W), the plasma duration and N{sub 2} flow rate were the most significant factors. The lowest sheet resistance values (163 Ω/sq. for a 20 nm TiN film) were obtained using plasma durations ∼40 s, N{sub 2} flow rates >60 standard cubic centimeters per minute, and purge times ∼60 s. Time of flight secondary ion mass spectroscopy data revealed reduced levels of carbon contaminants in the TiN films with lowest sheet resistance (163 Ω/sq.), compared to films with higher sheet resistance (400–600 Ω/sq.) while transmission electron microscopy data showed a higher density of nanocrystallites in the low-resistance films. Further significant reductions in sheet resistance, from 163 Ω/sq. to 70 Ω/sq. for a 20 nm TiN film (corresponding resistivity ∼145 μΩ·cm), were achieved by addition of a postcycle Ar/N{sub 2} plasma step in the PE-ALD process.

  8. Dust particle spin-up caused by cross-field plasma flow and turbulence.

    Science.gov (United States)

    Shukla, P. K.; Shevchenko, V. I.; Krasheninnikov, S. I.

    2006-10-01

    Spinning of dust particles adds new interesting features to dust particle dynamics and to the dusty plasma physics. Several reasons for dust particle spin-up have been suggested (e.g. Ref. 1): i) sheared flow of plasmas around charge dust particles, ii) dust particle surface irregularities, and iii) sheath effects resulting from the interactions of a charge dipole of a dust particle (caused by plasma flows into the sheath) with the sheath electric field. Here we present a novel mechanism for charged dust particle spin-up. The physics of the present mechanism is simple and robust, and is associated with the interaction of a charge dipole of a dust particle, D, induced by the ExB cross-field flow of a magnetized plasma (D ExB), where E and B are the electric and ambient magnetic fields. Since the resulting torque is proportional to | E |^2, the presented mechanism of charged dust particle spin-up works for both stationary and non-stationary (turbulent in particular) electric fields. In many cases the turbulent electric field stremgth is much larger than the laminar one so that the impact of turbulence can be dominant. We present theoretical analyses for charged dust particle spin-up and estimate the maximum value for the angular velocity charged dust particle can acquire due to our new spin-up mechanism. [1] N. Sato ``Spinning Motion of Fine Particles in Plasmas'', AIP Conference Proceedings No. 799, p. 97; AIP, New York, 2005.

  9. Multifluid MHD simulation of Saturn's magnetosphere: Dynamics of mass- and momentum-loading, and seasonal variation of the plasma sheet

    Science.gov (United States)

    Rajendar, A.; Paty, C. S.; Arridge, C. S.; Jackman, C. M.; Smith, H. T.

    2013-12-01

    Saturn's magnetosphere is driven externally, by the solar wind, and internally, by the planet's strong magnetic field, rapid rotation rate, and the addition of new plasma created from Saturn's neutral cloud. Externally, the alignment of the rotational and magnetic dipole axes, combined with Saturn's substantial inclination to its plane of orbit result in substantial curvature of the plasma sheet during solstice. Internally, new water group ions are produced in the inner regions of the magnetosphere from photoionization and electron-impact ionization of the water vapor and OH cloud sourced from Enceladus and other icy bodies in Saturn's planetary system. In addition to this, charge-exchange collisions between the relatively fast-moving water group ions and the slower neutrals results in a net loss of momentum from the plasma. In order to study these phenomena, we have made significant modifications to the Saturn multifluid model. This model has been previously used to investigate the external triggering of plasmoids and the interchange process using a fixed internal source rate. In order to improve the fidelity of the model, we have incorporated a physical source of mass- and momentum-loading by including an empirical representation of Saturn's neutral cloud and modifying the multifluid MHD equations to include mass- and momentum-loading terms. Collision cross-sections between ions, electrons, and neutrals are calculated as functions of closure velocity and energy at each grid point and time step, enabling us to simulate the spatially and temporally varying plasma-neutral interactions. In addition to this, by altering the angle of incidence of the solar wind relative to Saturn's rotational axis and applying a realistic latitudinally- and seasonally-varying ionospheric conductivity, we are also able to study seasonal effects on Saturn's magnetosphere. We use the updated multifluid simulation to investigate the dynamics of Saturn's magnetosphere, focusing specifically

  10. Evolution and structure of the plasma of current sheets forming in two-dimensional magnetic fields with a null line at low initial gas ionization and their interpretation

    Science.gov (United States)

    Ostrovskaya, G. V.; Frank, A. G.

    2012-04-01

    An analysis of the experimental data obtained by holographic interferometry in our work [1] makes it possible to explain most of the observed specific features of the structure and evolution of the plasma sheets developing in a two-dimensional magnetic field with a null line in a plasma with a low initial degree of ionization (≈10-4). The following two processes are shown to play a key role here: additional gas ionization in an electric field and the peculiarities of plasma dynamics in a current sheet expanding in time.

  11. Transport and trapping of dust particles in a potential well created by inductively coupled diffused plasma

    CERN Document Server

    Choudhary, Mangilal; Bandyopadhyay, P

    2016-01-01

    A versatile linear dusty (complex) plasma device is designed to study the transport and dynamical behavior of dust particles in a large volume. Diffused inductively coupled plasma is generated in the background of argon gas. A novel technique is used to introduce the dust particles in the main plasma by striking a secondary direct current (DC) glow discharge. These dust particles are found to get trapped in an electrostatic potential well which is formed due to the combination of the ambipolar electric field caused by diffusive plasma and the field produced by the charged glass wall of the vacuum chamber. According to the requirements, the volume of the dust cloud can be controlled very precisely by tuning the plasma and discharge parameters. The present device can be used to address the underlying physics behind the transport of dust particles, self excited dust acoustic waves and instabilities. The detailed design of this device, plasma production and characterization, trapping and transport of the dust par...

  12. Particle-in-Cell/Test-Particle Simulations of Technological Plasmas: Sputtering Transport in Capacitive Radio Frequency Discharges

    OpenAIRE

    Trieschmann, Jan; Schmidt, Frederik; Mussenbrock, Thomas

    2016-01-01

    The paper provides a tutorial to the conceptual layout of a self-consistently coupled Particle-In-Cell/Test-Particle model for the kinetic simulation of sputtering transport in capacitively coupled plasmas at low gas pressures. It explains when a kinetic approach is actually needed and which numerical concepts allow for the inherent nonequilibrium behavior of the charged and neutral particles. At the example of a generic sputtering discharge both the fundamentals of the applied Monte Carlo me...

  13. Study of the modification of spherical melamine-formaldehyde particles levitating in complex plasma

    Science.gov (United States)

    Karasev, V. Yu.; Polishchyuk, V. A.; Gorbenko, A. P.; Dzlieva, E. S.; Ermolenko, M. A.; Makar, M. M.

    2016-05-01

    The surface modification of spherical melamine-formaldehyde particles during their levitation in a dusty plasma as a part of plasma-dust structures in a trap formed in strata in a neon glow discharge has been investigated using scanning electron microscopy. The dependence of the particle size on the time of plasma exposure has been found and measured, and the modification of the surface structure has been studied. The source of the observed modification has been interpreted.

  14. Latitude-energy structure of multiple ion beamlets in Polar/TIMAS data in plasma sheet boundary layer and boundary plasma sheet below 6 RE radial distance: basic properties and statistical analysis

    Directory of Open Access Journals (Sweden)

    W. K. Peterson

    2005-03-01

    Full Text Available Velocity dispersed ion signatures (VDIS occurring at the plasma sheet boundary layer (PSBL are a well reported feature. Theory has, however, predicted the existence of multiple ion beamlets, similar to VDIS, in the boundary plasma sheet (BPS, i.e. at latitudes below the PSBL. In this study we show evidence for the multiple ion beamlets in Polar/TIMAS ion data and basic properties of the ion beamlets will be presented. Statistics of the occurrence frequency of ion multiple beamlets show that they are most common in the midnight MLT sector and for altitudes above 4 RE, while at low altitude (≤3 RE, single beamlets at PSBL (VDIS are more common. Distribution functions of ion beamlets in velocity space have recently been shown to correspond to 3-dimensional hollow spheres, containing a large amount of free energy. We also study correlation with ~100 Hz waves and electron anisotropies and consider the possibility that ion beamlets correspond to stable auroral arcs.

  15. ISEE-3 observations of a viscously-driven plasma sheet: magnetosheath mass and/or momentum transfer?

    Science.gov (United States)

    Mist, R. T.; Owen, C. J.

    2002-05-01

    A statistical analysis of data from the ISEE-3 distant tail campaign is presented. We investigate the mechanism driving slow, tailward flows observed in the plasma sheet. The possibility that these slow flows are driven by mass and/or momentum transfer across the distant tail magnetopause is explored. We establish that 40% of these flows could be driven by the transfer of approximately 4% of the magnetosheath momentum flux into the magnetotail. Current understanding of the Kelvin-Helmholtz instability suggests that this figure is consistent with the amount of momentum flux transfer produced by this mechanism. We also consider the possibility that these flows are solely driven by transferring magnetosheath plasma across the magnetopause. We find that there is sufficient mass observed on these field lines for this to be the sole driving mechanism for only 27% of the observed slow flows.

  16. Flow characteristic of in-flight particles in supersonic plasma spraying process

    Science.gov (United States)

    Wei, Pei; Wei, Zhengying; Zhao, Guangxi; Du, Jun; Bai, Y.

    2016-09-01

    In this paper, a computational model based on supersonic plasma spraying (SAPS) is developed to describe the plasma jet coupled with the injection of carrier gas and particles for SAPS. Based on a high-efficiency supersonic spraying gun, the 3D computational model of spraying gun was built to study the features of plasma jet and its interactions with the sprayed particles. Further the velocity and temperature of in-flight particles were measured by Spray Watch 2i, the shape of in-flight particles was observed by scanning electron microscope. Numerical results were compared with the experimental measurements and a good agreement has been achieved. The flight process of particles in plasma jet consists of three stages: accelerated stage, constant speed stage and decelerated stage. Numerical and experimental indicates that the H2 volume fraction in mixture gas of Ar + H2 should keep in the range of 23-26 %, and the distance of 100 mm is the optimal spraying distance in Supersonic atmosphere plasma spraying. Particles were melted and broken into small child particles by plasma jet and the diameters of most child particles were less than 30 μm. In general, increasing the particles impacting velocity and surface temperature can decrease the coating porosity.

  17. Tailoring particle arrays by isotropic plasma etching: an approach towards percolated perpendicular media

    NARCIS (Netherlands)

    Brombacher, C.; Saitner, M.; Pfahler, C.; Plettl, A.; Ziemann, P.; Makarov, D.; Assmann, D.; Siekman, Martin Herman; Abelmann, Leon; Albrecht, M.

    2009-01-01

    Plasma etching of densely packed arrays of polystyrene particles leads to arrays of spherical nanostructures with adjustable diameters while keeping the periodicity fixed. A linear dependence between diameter of the particles and etching time was observed for particles down to sizes of sub-50 nm.

  18. Kinetic temperature of dust particle motion in gas-discharge plasma

    NARCIS (Netherlands)

    Norman, G. E.; Timofeev, A. V.

    2011-01-01

    A system of equations describing motion of dust particles in gas discharge plasma is formulated. This system is developed for a monolayer of dust particles with an account of dust particle charge fluctuations and features of the discharge near-electrode layer. Molecular dynamics simulation of the du

  19. Resonant scattering of central plasma sheet protons by multiband EMIC waves and resultant proton loss timescales

    Science.gov (United States)

    Cao, Xing; Ni, Binbin; Liang, Jun; Xiang, Zheng; Wang, Qi; Shi, Run; Gu, Xudong; Zhou, Chen; Zhao, Zhengyu; Fu, Song; Liu, Jiang

    2016-02-01

    This is a companion study to Liang et al. (2014) which reported a "reversed" energy-latitude dispersion pattern of ion precipitation in that the lower energy ion precipitation extends to lower latitudes than the higher-energy ion precipitation. Electromagnetic ion cyclotron (EMIC) waves in the central plasma sheet (CPS) have been suggested to account for this reversed-type ion precipitation. To further investigate the association, we perform a comprehensive study of pitch angle diffusion rates induced by EMIC wave and the resultant proton loss timescales at L = 8-12 around the midnight. Comparing the proton scattering rates in the Earth's dipole field and a more realistic quiet time geomagnetic field constructed from the Tsyganenko 2001 (T01) model, we find that use of a realistic, nondipolar magnetic field model not only decreases the minimum resonant energies of CPS protons but also considerably decreases the limit of strong diffusion and changes the proton pitch angle diffusion rates. Adoption of the T01 model increases EMIC wave diffusion rates at > ~ 60° equatorial pitch angles but decreases them at small equatorial pitch angles. Pitch angle scattering coefficients of 1-10 keV protons due to H+ band EMIC waves can exceed the strong diffusion rate for both geomagnetic field models. While He+ and O+ band EMIC waves can only scatter tens of keV protons efficiently to cause a fully filled loss cone at L > 10, in the T01 magnetic field they can also cause efficient scattering of ~ keV protons in the strong diffusion limit at L > 10. The resultant proton loss timescales by EMIC waves with a nominal amplitude of 0.2 nT vary from a few hours to several days, depending on the wave band and L shell. Overall, the results demonstrate that H+ band EMIC waves, once present, can act as a major contributor to the scattering loss of a few keV protons at lower L shells in the CPS, accounting for the reversed energy-latitude dispersion pattern of proton precipitation at low

  20. Effects of solar wind ultralow-frequency fluctuations on plasma sheet electron temperature: Regression analysis with support vector machine

    Science.gov (United States)

    Wang, Chih-Ping; Kim, Hee-Jeong; Yue, Chao; Weygand, James M.; Hsu, Tung-Shin; Chu, Xiangning

    2017-04-01

    To investigate whether ultralow-frequency (ULF) fluctuations from 0.5 to 8.3 mHz in the solar wind and interplanetary magnetic field (IMF) can affect the plasma sheet electron temperature (Te) near geosynchronous distances, we use a support vector regression machine technique to decouple the effects from different solar wind parameters and their ULF fluctuation power. Te in this region varies from 0.1 to 10 keV with a median of 1.3 keV. We find that when the solar wind ULF power is weak, Te increases with increasing southward IMF Bz and solar wind speed, while it varies weakly with solar wind density. As the ULF power becomes stronger during weak IMF Bz ( 0) or northward IMF, Te becomes significantly enhanced, by a factor of up to 10. We also find that mesoscale disturbances in a time scale of a few to tens of minutes as indicated by AE during substorm expansion and recovery phases are more enhanced when the ULF power is stronger. The effect of ULF powers may be explained by stronger inward radial diffusion resulting from stronger mesoscale disturbances under higher ULF powers, which can bring high-energy plasma sheet electrons further toward geosynchronous distance. This effect of ULF powers is particularly important during weak southward IMF or northward IMF when convection electric drift is weak.

  1. Multi-instrument observations of the ionospheric counterpart of a bursty bulk flow in the near-Earth plasma sheet

    Directory of Open Access Journals (Sweden)

    A. Grocott

    2004-04-01

    Full Text Available On 07 September 2001 the Cluster spacecraft observed a "bursty bulk flow" event in the near-Earth central plasma sheet. This paper presents a detailed study of the coincident ground-based observations and attempts to place them within a simple physical framework. The event in question occurs at ~22:30 UT, some 10min after a southward turning of the IMF. IMAGE and SAMNET magnetometer measurements of the ground magnetic field reveal perturbations of a few tens of nT and small amplitude Pi2 pulsations. CUTLASS radar observations of ionospheric plasma convection show enhanced flows out of the polar cap near midnight, accompanied by an elevated transpolar voltage. Optical data from the IMAGE satellite also show that there is a transient, localised ~1 kR brightening in the UV aurora. These observations are consistent with the earthward transport of plasma in the tail, but also indicate the absence of a typical "large-scale" substorm current wedge. An analysis of the field-aligned current system implied by the radar measurements does suggest the existence of a small-scale current "wedgelet", but one which lacks the global scale and high conductivities observed during substorm expansions.

    Key words. Ionosphere (auroral ionosphere; ionospheremagnetosphere interactions; plasma convection

  2. Temperature measurement of a dust particle in a RF plasma GEC reference cell

    CERN Document Server

    Kong, Jie; Matthews, Lorin S; Hyde, Truell W

    2016-01-01

    The thermal motion of a dust particle levitated in a plasma chamber is similar to that described by Brownian motion in many ways. The primary differences between a dust particle in a plasma system and a free Brownian particle is that in addition to the random collisions between the dust particle and the neutral gas atoms, there are electric field fluctuations, dust charge fluctuations, and correlated motions from the unwanted continuous signals originating within the plasma system itself. This last contribution does not include random motion and is therefore separable from the random motion in a normal temperature measurement. In this paper, we discuss how to separate random and coherent motion of a dust particle confined in a glass box in a Gaseous Electronic Conference radio frequency reference cell employing experimentally determined dust particle fluctuation data analyzed using the mean square displacement technique.

  3. Channeling of particles and associated anomalous transport in a 2D complex plasma crystal

    CERN Document Server

    Du, Cheng-Ran; Zhdanov, Sergey; Thomas, Hubertus M; Morfill, Gregor E

    2013-01-01

    Implications of recently discovered effect of channeling of upstream extra particles for transport phenomena in a two-dimensional plasma crystal are discussed. Upstream particles levitated above the lattice layer and tended to move between the rows of lattice particles. An example of heat transport is considered, where upstream particles act as moving heat sources, which may lead to anomalous heat transport. The average channeling length observed was 15 - 20 interparticle distances. New features of the channeling process are also reported.

  4. Observation of particle pairing in a two-dimensional plasma crystal

    CERN Document Server

    Zhdanov, S K; Nosenko, V; Thomas, H M; Morfill, G E

    2013-01-01

    The observation is presented of naturally occurring pairing of particles and their cooperative drift in a two-dimensional plasma crystal. A single layer of plastic microspheres was suspended in the plasma sheath of a capacitively coupled rf discharge in argon at a low pressure of 1 Pa. The particle dynamics were studied by combining the top-view and side-view imaging of the suspension. Cross analysis of the particle trajectories allowed us to identify naturally occurring metastable pairs of particles. The lifetime of pairs was long enough for their reliable identification.

  5. Neutral Particle Transport in Cylindrical Plasma Simulated by a Monte Carlo Code

    Institute of Scientific and Technical Information of China (English)

    YU Deliang; YAN Longwen; ZHONG Guangwu; LU Jie; YI Ping

    2007-01-01

    A Monte Carlo code (MCHGAS) has been developed to investigate the neutral particle transport.The code can calculate the radial profile and energy spectrum of neutral particles in cylindrical plasmas.The calculation time of the code is dramatically reduced when the Splitting and Roulette schemes are applied. The plasma model of an infinite cylinder is assumed in the code,which is very convenient in simulating neutral particle transports in small and middle-sized tokamaks.The design of the multi-channel neutral particle analyser (NPA) on HL-2A can be optimized by using this code.

  6. Development of innovative thermal plasma and particle diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Bachmann, Benjamin-Leon

    2013-09-24

    Three original plasma diagnostic systems have been developed to investigate transient three-dimensional plasma processes with high spatial and temporal resolution. The developed diagnostics have been analyzed and tested by increasing the complexity from a stationary free burning Argon arc to a dc pulsed process and finally to a transient gas metal arc including droplet transfer through the plasma. The transient plasma parameters that have been determined include three-dimensional axially symmetric plasma densities (n{sub e}, n{sub A}, n{sub A+}, n{sub A++}), electron temperatures (T{sub e}), electrical conductivities (σ{sub el}), magnetic flux densities (B) and current densities (j{sub el}). In the case of a droplet transfer through an arc consisting of an Iron/Argon plasma, the droplet density, surface tension, viscosity, and temperature have been determined.

  7. Sheet beam model for intense space-charge: with application to Debye screening and the distribution of particle oscillation frequencies in a thermal equilibrium beam

    Energy Technology Data Exchange (ETDEWEB)

    Lund, Steven M.; Friedman, Alex; Bazouin, Guillaume

    2011-01-10

    A one-dimensional Vlasov-Poisson model for sheet beams is reviewed and extended to provide a simple framework for analysis of space-charge effects. Centroid and rms envelope equations including image charge effects are derived and reasonable parameter equivalences with commonly employed 2D transverse models of unbunched beams are established. This sheet beam model is then applied to analyze several problems of fundamental interest. A sheet beam thermal equilibrium distribution in a continuous focusing channel is constructed and shown to have analogous properties to two- d three-dimensional thermal equilibrium models in terms of the equilibrium structure and Deybe screening properties. The simpler formulation for sheet beams is exploited to explicitly calculate the distribution of particle oscillation frequencies within a thermal equilibrium beam. It is shown that as space-charge intensity increases, the frequency distribution becomes broad, suggesting that beams with strong space-charge can have improved stability.

  8. Dust particle formation due to interaction between graphite and helicon deuterium plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Iwashita, Shinya, E-mail: shinya.iwashita@rub.de [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Nishiyama, Katsushi; Uchida, Giichiro; Seo, Hyunwoong; Itagaki, Naho; Koga, Kazunori [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Shiratani, Masaharu, E-mail: siratani@ed.kyushu-u.ac.jp [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan)

    2013-01-15

    The collection of dust particles using divertor simulation helicon plasmas has been carried out to examine dust formation due to the interaction between a graphite target and deuterium plasmas, which are planned to operate in the large helical device (LHD) at the Japanese National Institute for Fusion Science (NIFS). The collected dust particles are classified into three types: (i) small spherical particles below 400 nm in size, (ii) agglomerates whose primary particles have a size of about 10 nm, and (iii) large flakes above 1 {mu}m in size. These features are quite similar to those obtained through hydrogen plasma operation, indicating that the dust formation mechanisms due to the interaction between a carbon wall and a plasma of deuterium, which is the isotope of hydrogen, is probably similar to those of hydrogen.

  9. Stimulated Brillouin scattering of an electromagnetic wave in weakly magnetized plasma with variably charged dust particles

    Indian Academy of Sciences (India)

    Sourabh Bal; M Bose

    2009-10-01

    We have investigated analytically the stimulated Brillouin scattering (SBS) of an electromagnetic wave in non-dissipative weakly magnetized plasma in the presence of dust particles with variable charge.

  10. Novel fragmentation model for pulverized coal particles gasification in low temperature air thermal plasma

    OpenAIRE

    Jovanović Rastko D.; Cvetinović Dejan B.; Stefanović Predrag Lj.; Škobalj Predrag D.; Marković Zoran J.

    2016-01-01

    New system for start-up and flame support based on coal gasification by low temperature air thermal plasma is planned to supplement current heavy oil system in Serbian thermal power plants in order to decrease air pollutions emission and operational costs. Locally introduced plasma thermal energy heats up and ignites entrained coal particles, thus starting chain process which releases heat energy from gasified coal particles inside burner channel. Important...

  11. Scaling theory of relative diffusion of charged particles in a weakly magneto-turbulent plasma

    Energy Technology Data Exchange (ETDEWEB)

    Haida Wang (University of Science and Technology of China, Hefei, Anhui. Dept. of Modern Physics); Xiaoming Qui (Southwest Inst. of Physics, Leshan, SC (China))

    1989-02-01

    Stochastic motion of charged particles in a magneto-turbulent plasma is studied for the whole time region. A set of nonlinear differential equations for describing relative spatial diffusion of charged particles is derived and some explicit results are obtained in the case of a weak magnetic field. It is found that, for the diffusion in the present system there are some new and interesting properties which do not exist in an unmagnetized plasma. The clump effect is also discussed. (author).

  12. Observation of a planetward ion beam in the plasma sheet boundary layer at Saturn following tail reconnection

    Science.gov (United States)

    Jackman, C. M.

    2014-04-01

    We present an interval of data from 2006 when the Cassini spacecraft was located 32 RS (1 RS = 60268km) downtail, at a local time of 22:00 hrs and a latitude of 13.8°. The interval in question displayed a range of dynamic behaviour, including a southward turning of the tail magnetic field, indicative of a dipolarization, and an energetic, fast, planetward beam of ions. Preliminary interpretation of this event suggests that it represents a reconnection-driven ion beam in Saturn's magnetotail plasma sheet boundary layer. This event is explored using several of the Cassini instruments to build up a picture of the reconfiguration of the tail in terms of local and global effects.

  13. Relationship between FAC at plasma sheet boundary layers and AE index during storms from August to October,2001

    Institute of Scientific and Technical Information of China (English)

    DUNLOP; M

    2008-01-01

    Unlike the previous single (dual) satellite observation, the four ClusterII satellites make it possible to directly compute the continuous field-aligned current (FAC) density according to the magnetic data from them and to enable the investigation of the relationship between the FAC and geomagnetic activity. This paper analyzes the observation data when the Cluster satellites crossed the plasma sheet bound- ary layer (PSBL) in the magnetotail during the two magnetic storms in August to October 2001. According to the data, during the magnetic storms the relationship between the variations of FAC and AE index turned out to be: 1) FAC was obviously increasing during the storms; 2) FAC density was approximately negatively corre- lated with AE index from the sudden commencement to the early main phase of the storm; 3) they were approximately positively correlated during the late main phase and early recovery phase; 4) they were no apparent correlation during the late re- covery phase.

  14. Production of high transient heat and particle fluxes in a linear plasma device

    NARCIS (Netherlands)

    De Temmerman, G.; Zielinski, J. J.; van der Meiden, H.; Melissen, W.; Rapp, J.

    2010-01-01

    We report on the generation of high transient heat and particle fluxes in a linear plasma device by pulsed operation of the plasma source. A capacitor bank is discharged into the source to transiently increase the discharge current up to 1.7 kA, allowing peak densities and temperature of 70x10(20) m

  15. Core Fueling and Edge Particle Flux Analysis in Ohmically and Auxiliary Heated NSTX Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    V.A. Soukhanovskii; R. Maingi; R. Raman; H.W. Kugel; B.P. LeBlanc; L. Roquemore; C.H. Skinner; NSTX Research Team

    2002-06-12

    The Boundary Physics program of the National Spherical Torus Experiment (NSTX) is focusing on optimization of the edge power and particle flows in b * 25% L- and H-mode plasmas of t {approx} 0.8 s duration heated by up to 6 MW of high harmonic fast wave and up to 5 MW of neutral beam injection. Particle balance and core fueling efficiencies of low and high field side gas fueling of L-mode homic and NBI heated plasmas have been compared using an analytical zero dimensional particle balance model and measured ion and neutral fluxes. Gas fueling efficiencies are in the range of 0.05-0.20 and do not depend on discharge magnetic configuration, density or poloidal location of the injector. The particle balance modeling indicates that the addition of HFS fueling results in a reversal of the wall loading rate and higher wall inventories. Initial particle source estimates obtained from neutral pressure and spectroscopic measurements indicate that ion flux into the divertor greatly exceeds midplane ion flux from the main plasma, suggesting that the scrape-off cross-field transport plays a minor role in diverted plasmas. Present analysis provides the basis for detailed fluid modeling of core and edge particle flows and particle confinement properties of NSTX plasmas. This research was supported by the U.S. Department of Energy under contracts No. DE-AC02-76CH03073, DE-AC05-00OR22725, and W-7405-ENG-36.

  16. A Novel Source of Mesoscopic Particles for Laser Plasma Studies

    Science.gov (United States)

    2015-12-16

    05/2016 DISTRIBUTION A: Distribution approved for public release. AF Office Of Scientific Research (AFOSR)/ IOA Arlington, Virginia 22203 Air Force...particles is obtained (gas pulsing is essential to maintain the vacuum level). To visualise the particles, a shadowgraph based imag- ing set up was

  17. Depletion of abundant plasma proteins by poly(N-isopropylacrylamide-acrylic acid) hydrogel particles

    DEFF Research Database (Denmark)

    Such-Sanmartín, Gerard; Ventura-Espejo, Estela; Jensen, Ole N

    2014-01-01

    at higher efficiency than low abundance proteins, which are enriched in the supernatants, whereas (2) hydrogel particles incubated with high concentrations of plasma capture and irreversibly trap abundant proteins. During the elution step, irreversibly trapped proteins remain captured while low abundance...... (SRM) liquid chromatography (LC)-MS/MS. This novel use of hydrogel particles opens new perspectives for biomarker analysis based on mass spectrometry....

  18. 3D particle tracking velocimetry using dynamic discrete tomography for plasma physics applications

    DEFF Research Database (Denmark)

    Moseev, Dmitry; Alpers, Andreas; Gritzmann, Peter

    2013-01-01

    -pixel sized particles as greylevel images. Reconstructions obtained by these methods do not necessarily match the experimental data. We propose a new algorithm which can be used for tracking dust particles in tokamaks and stellarators, as well as in low-temperature and complex plasmas. The dynamic discrete...

  19. Conditions for laser-induced plasma to effectively remove nano-particles on silicon surfaces

    Science.gov (United States)

    Han, Jinghua; Luo, Li; Zhang, Yubo; Hu, Ruifeng; Feng, Guoying

    2016-09-01

    Particles can be removed from a silicon surface by means of irradiation and a laser plasma shock wave. The particles and silicon are heated by the irradiation and they will expand differently due to their different expansion coefficients, making the particles easier to be removed. Laser plasma can ionize and even vaporize particles more significantly than an incident laser and, therefore, it can remove the particles more efficiently. The laser plasma shock wave plays a dominant role in removing particles, which is attributed to its strong burst force. The pressure of the laser plasma shock wave is determined by the laser pulse energy and the gap between the focus of laser and substrate surface. In order to obtain the working conditions for particle removal, the removal mechanism, as well as the temporal and spatial characteristics of velocity, propagation distance and pressure of shock wave have been researched. On the basis of our results, the conditions for nano-particle removal are achieved. Project supported by the National Natural Science Foundation of China (Grant No. 11574221).

  20. Design of a plasma discharge circuit for particle wakefield acceleration

    CERN Document Server

    Anania, M P; Cianchi, A; Di Giovenale, D; Ferrario, M; Flora, F; Gallerano, G P; Ghigo, A; Marocchino, A; Massimo, F; Mostacci, A; Mezi, L; Musumeci, P; Serio, M; 10.1016/j.nima.2013.10.053

    2014-01-01

    Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10-100 GV m^-1), enabling acceleration of electrons to GeV energy in few centimetres. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators; radiofrequency-based accelerators, in fact, are limited in the accelerating field (10-100 MV m^-1) requiring therefore kilometric distances to reach the GeV energies, but can provide very bright electron bunches. Combining high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of shor...

  1. MONTE CARLO SIMULATION OF CHARGED PARTICLE IN AN ELECTRONEGATIVE PLASMA

    Directory of Open Access Journals (Sweden)

    L SETTAOUTI

    2003-12-01

    Full Text Available Interest in radio frequency (rf discharges has grown tremendously in recent years due to their importance in microelectronic technologies. Especially interesting are the properties of discharges in electronegative gases which are most frequently used for technological applications. Monte Carlo simulation have become increasingly important as a simulation tool particularly in the area of plasma physics. In this work, we present some detailed properties of rf plasmas obtained by Monte Carlo simulation code, in SF6

  2. Zonal flow driven by energetic particle during magneto-hydro-dynamic burst in a toroidal plasma

    Science.gov (United States)

    Ohshima, S.; Fujisawa, A.; Shimizu, A.; Nakano, H.; Iguchi, H.; Yoshimura, Y.; Nagaoka, K.; Minami, T.; Isobe, M.; Nishimura, S.; Suzuki, C.; Akiyama, T.; Takahashi, C.; Takeuchi, M.; Ito, T.; Watari, T.; Kumazawa, R.; Itoh, S.-I.; Itoh, K.; Matsuoka, K.; Okamura, S.

    2007-11-01

    The internal structural measurements of electric field and density using twin heavy ion beam probes have been performed to elucidate the nonlinear evolution of the magneto-hydro-dynamic (MHD) bursty phenomenon driven by the interaction with high-energy particles in a toroidal plasma. The results have given the finest observation of the internal structure of plasma quantities, such as electric field, density and magnetic field distortion, which nonlinearly develop during the MHD phenomenon. In particular, the finding of a new kind of oscillating zonal flow driven by interaction between energetic particles and MHD modes should be emphasized for burning state plasmas.

  3. Separation Process of Polydisperse Particles in the Plasma of Radio-frequency Discharge

    Directory of Open Access Journals (Sweden)

    D.G. Batryshev

    2014-07-01

    Full Text Available Method of separation of polydisperse particles in the plasma of radio-frequency (RF discharge is considered. Investigation of plasma equipotential field gave conditions for separation. The purpose of this work was an obtaining of monodisperse particles in the plasma of RF discharge. Samples of monodisperse microparticles of silica and alumina were obtained. The size and chemical composition of samples were studied on a scanning electron microscope Quanta 3D 200i (SEM, USA FEI company. Average size of separated silica nanoparticles is 600 nm, silica and alumina microparticles is 5 mkm.

  4. Phase Separation of Binary Charged Particle Systems with Small Size Disparities using a Dusty Plasma.

    Science.gov (United States)

    Killer, Carsten; Bockwoldt, Tim; Schütt, Stefan; Himpel, Michael; Melzer, André; Piel, Alexander

    2016-03-18

    The phase separation in binary mixtures of charged particles has been investigated in a dusty plasma under microgravity on parabolic flights. A method based on the use of fluorescent dust particles was developed that allows us to distinguish between particles of slightly different size. A clear trend towards phase separation even for smallest size (charge) disparities is observed. The diffusion flux is directly measured from the experiment and uphill diffusion coefficients have been determined.

  5. Using Field-Particle Correlations to Diagnose the Collisionless Damping of Plasma Turbulence

    Science.gov (United States)

    Howes, Gregory; Klein, Kristropher

    2016-10-01

    Plasma turbulence occurs ubiquitously throughout the heliosphere, yet our understanding of how turbulence governs energy transport and plasma heating remains incomplete, constituting a grand challenge problem in heliophysics. In weakly collisional heliospheric plasmas, such as the solar corona and solar wind, damping of the turbulent fluctuations occurs due to collisionless interactions between the electromagnetic fields and the individual plasma particles. A particular challenge in diagnosing this energy transfer is that spacecraft measurements are typically limited to a single point in space. Here we present an innovative field-particle correlation technique that can be used with single-point measurements to estimate the energization of the plasma particles due to the damping of the electromagnetic fields, providing vital new information about this how energy transfer is distributed as a function of particle velocity. This technique has the promise to transform our ability to diagnose the kinetic plasma physical mechanisms responsible for not only the damping of turbulence, but also the energy conversion in both collisionless magnetic reconnection and particle acceleration. The work has been supported by NSF CAREER Award AGS-1054061, NSF AGS-1331355, and DOE DE-SC0014599.

  6. Nanoshaping field emitters from glassy carbon sheets: a new functionality induced by H-plasma etching.

    Science.gov (United States)

    Gay, S; Orlanducci, S; Passeri, D; Rossi, M; Terranova, M L

    2016-09-14

    This paper reports on the morphological and electrical characterization at the nanometer scale and the investigation of the field emission characteristics of glassy carbon (GC) plates which underwent H-induced physical/chemical processes occurring in a dual-mode MW-RF plasma reactor. Plasma treatment produced on the GC surface arrays of vertically aligned conically shaped nanostructures, with density and height depending on the plasma characteristics. Two kinds of samples obtained under two different bias regimes have been deeply analyzed using an AFM apparatus equipped with tools for electric forces and surface potential measurements. The features of electron emission via the Field Emission (FE) mechanism have been correlated with the morphology and the structure at the nanoscale of the treated glassy carbon samples. The measured current density and the characteristics of the emission, which follow the Fowler-Nordheim law, indicate that the plasma-based methodology utilized for the engineering of the GC surfaces is able to turn conventional GC plates into efficient emission devices. The outstanding properties of GC suggest the use of such nanostructured materials for the assembling of cold cathodes to be used in a harsh environment and under extreme P/T conditions.

  7. Hydrophobization of polymer particles by tetrafluoromethane (CF{sub 4}) plasma irradiation using a barrel-plasma-treatment system

    Energy Technology Data Exchange (ETDEWEB)

    Matsubara, Keisuke; Danno, Masato; Inoue, Mitsuhiro; Nishizawa, Hideki; Honda, Yuji; Abe, Takayuki, E-mail: tabe@ctg.u-toyama.ac.jp

    2013-11-01

    In this study, tetrafluoromethane (CF{sub 4}) plasma-treatments of polymethylmethacrylate (PMMA) powder were performed using a polygonal barrel-plasma-treatment system to improve the PMMA's hydrophobicity. Characterization of the treated samples showed that the PMMA particle surfaces were fluorinated by the CF{sub 4} treatment. The smooth surfaces of the particles changed into nano-sized worm-like structures after the plasma-treatment. The hydrophobicity of the treated PMMA samples was superior to that of the untreated samples. It was noted that the hydrophobicity of the treated samples and the surface fluorination level depended on the plasma-treatment time and radiofrequency (RF) power; high RF power increased the sample temperature, which in turn decreased the hydrophobicity of the treated samples and the surface fluorination because of the thermal decomposition of PMMA. The water-repellent effects were evaluated by using paper towels to show the application of the plasma-treated PMMA particles, with the result that the paper towel coated with the treated sample was highly water-repellent.

  8. Interplay between plasma turbulence and particle injection in 3D global simulations

    Energy Technology Data Exchange (ETDEWEB)

    Tamain, P.; Baudoin, C.; Ciraolo, G.; Futtersack, R.; Ghendrih, P.; Nace, N. [Association Euratom-CEA, Institut de Recherche sur la Fusion Magnetique, CEA Cadarache, St. Paul-lez-Durance (France); Bufferand, H.; Carbajal, L.; Marandet, Y. [Aix-Marseille Universite, CNRS, PIIM, UMR 7345, Marseille (France); Colin, C.; Galassi, D.; Schwander, F.; Serre, E. [Aix-Marseille Universite, CNRS, Ecole Centrale Marseille, M2P2, Marseille (France)

    2016-08-15

    The impact of a 3D localized particle source on the edge plasma in 3D global turbulence simulations is investigated using the TOKAM3X fluid code. Results apply to advanced fueling methods such as Supersonic Molecular Beam Injection (SMBI) or pellets injection. The fueling source is imposed as a volumetric particle source in the simulations so that the physics leading to the ionization of particles and its localization are not taken into account. As already observed in experiments, the localized particle source strongly perturbs both turbulence and the large scale organization of the edge plasma. The localized increase of the pressure generated by the source drives sonic parallel flows in the plasma, leading to a poloidal redistribution of the particles on the time scale of the source duration. However, the particle deposition also drives localized transverse pressure gradients which impacts the stability of the plasma with respect to interchange processes. The resulting radial transport occurs on a sufficiently fast time scale to compete with the parallel redistribution of particles, leading to immediate radial losses of a significant proportion of the injected particles. Low Field Side (LFS) and High Field Side (HFS) injections exhibit different dynamics due to their interaction with curvature. In particular, HFS particle deposition drives an inward flux leading to differences in the particle deposition efficiency (higher for HFS than LFS). These results demonstrate the importance of taking into account plasma transport in a self-consistent manner when investigating fueling methods. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Particles as probes for complex plasmas in front of biased surfaces

    CERN Document Server

    Basner, R; Loffhagen, D; Schubert, G; Fehske, H; Kersten, H

    2008-01-01

    An interesting aspect in the research of complex (dusty) plasmas is the experimental study of the interaction of micro-particles with the surrounding plasma for diagnostic purposes. Local electric fields can be determined from the behaviour of particles in the plasma, e.g. particles may serve as electrostatic probes. Since in many cases of applications in plasma technology it is of great interest to describe the electric field conditions in front of floating or biased surfaces, the confinement and behaviour of test particles is studied in front of floating walls inserted into a plasma as well as in front of additionally biased surfaces. For the latter case, the behaviour of particles in front of an adaptive electrode, which allows for an efficient confinement and manipulation of the grains, has been experimentally studied in dependence on the discharge parameters and on different bias conditions of the electrode. The effect of the partially biased surface (dc, rf) on the charged micro-particles has been inves...

  10. Investigation on in-flight particle velocity in supersonic plasma spraying

    Institute of Scientific and Technical Information of China (English)

    Li Changqing; Ma Shining; Ye Xionglin

    2005-01-01

    In-flight particle velocity and flux distribution were measured using CCD thermal spray monitor system during supersonic plasma spray processing with nano-structured Al203-TiO2 feed stocks. According to the results of particle flux measurement, the largest radian of the divergent particle stream is about 0. 2. Within the measuring range, top speed of inflight particles reached 800 m/s. Particle acceleration was accomplished within 4 cm down stream of the nozzle. Average particle velocity ( about 450 m/s) exceeded local sound speed (340 m/s) even at a mean standoff distance of 17 cm. With increasing mean standoff distance, average velocity of in-flight particle decreased according to a parabolic rule approximately.Image diagnosis showed that the result of in-flight particle velocity measurement is credible.

  11. Particle-In-Cell Modeling of Plasma-Based Accelerators in Two and Three Dimensions

    CERN Document Server

    Hemker, Roy G

    2015-01-01

    In this dissertation, a fully object-oriented, fully relativistic, multi-dimensional Particle-In-Cell code was developed and applied to answer key questions in plasma-based accelerator research. The simulations increase the understanding of the processes in laser plasma and beam-plasma interaction, allow for comparison with experiments, and motivate the development of theoretical models. The simulations support the idea that the injection of electrons in a plasma wave by using a transversely propagating laser pulse is possible. The beam parameters of the injected electrons found in the simulations compare reasonably with beams produced by conventional methods and therefore laser injection is an interesting concept for future plasma-based accelerators. Simulations of the optical guiding of a laser wakefield driver in a parabolic plasma channel support the idea that electrons can be accelerated over distances much longer than the Rayleigh length in a channel. Simulations of plasma wakefield acceleration in the ...

  12. Trans-Relativistic Particle Acceleration in Astrophysical Plasmas

    Science.gov (United States)

    Becker, Peter A.; Subramanian, P.

    2014-01-01

    Trans-relativistic particle acceleration due to Fermi interactions between charged particles and MHD waves helps to power the observed high-energy emission in AGN transients and solar flares. The trans-relativistic acceleration process is challenging to treat analytically due to the complicated momentum dependence of the momentum diffusion coefficient. For this reason, most existing analytical treatments of particle acceleration assume that the injected seed particles are already relativistic, and therefore they are not suited to study trans-relativistic acceleration. The lack of an analytical model has forced workers to rely on numerical simulations to obtain particle spectra describing the trans-relativistic case. In this work we present the first analytical solution to the global, trans-relativistic problem describing the acceleration of seed particles due to hard-sphere collisions with MHD waves. The new results include the exact solution for the steady-state Green's function resulting from the continual injection of monoenergetic seed particles with an arbitrary energy. We also introduce an approximate treatment of the trans-relativistic acceleration process based on a hybrid form for the momentum diffusion coefficient, given by the sum of the two asymptotic forms. We refer to this process as "quasi hard-sphere scattering." The main advantage of the hybrid approximation is that it allows the extension of the physical model to include (i) the effects of synchrotron and inverse-Compton losses and (ii) time dependence. The new analytical results can be used to model the trans-relativistic acceleration of particles in AGN and solar environments, and can also be used to compute the spectra of the associated synchrotron and inverse-Compton emission. Applications of both types are discussed. We highlight (i) relativistic ion acceleration in black hole accretion coronae, and (ii) the production of gyrosynchrotron microwave emission due to relativistic electron

  13. Temperature Measurement Challenges and Limitations for In-Flight Particles in Suspension Plasma Spraying

    Science.gov (United States)

    Aziz, Bishoy; Gougeon, Patrick; Moreau, Christian

    2017-03-01

    Suspension plasma spraying (SPS) acquires a significant interest from the industry. The deposited coatings using this technique were proved to have unique microstructural features compared to those built by conventional plasma spraying techniques. In order to optimize this process, in-flight particle diagnostics is considered a very useful tool that helps to control various spraying parameters and permits better coating reproducibility. In that context, the temperature of in-flight particles is one of the most important key elements that helps to optimize and control the SPS process. However, the limitations and challenges associated with this process have a significant effect on the accuracy of two-color pyrometric techniques used to measure the in-flight particle temperature. In this work, the influence of several nonthermal radiation sources on the particle temperature measurement is studied. The plasma radiation scattered by in-flight particles was found to have no significant influence on temperature measurement. Moreover, the detection of the two-color signals at two different locations was found to induce a significant error on temperature measurement. Finally, the plasma radiation surrounding the in-flight particles was identified as the main source of error on the temperature measurement of in-flight particles.

  14. Plasma Panel Sensors for Particle and Beam Detection

    CERN Document Server

    Friedman, Peter S; Beene, James R; Benhammou, Yan; Bentefour, E H; Chapman, J W; Etzion, Erez; Ferretti, Claudio; Guttman, Nir; Levin, Daniel S; Ben-Moshe, Meny; Silver, Yiftah; Varner, Robert L; Weaverdyck, Curtis; Zhou, Bing

    2012-01-01

    The plasma panel sensor (PPS) is an inherently digital, high gain, novel variant of micropattern gas detectors inspired by many operational and fabrication principles common to plasma display panels (PDPs). The PPS is comprised of a dense array of small, plasma discharge, gas cells within a hermetically-sealed glass panel, and is assembled from non-reactive, intrinsically radiation-hard materials such as glass substrates, metal electrodes and mostly inert gas mixtures. We are developing the technology to fabricate these devices with very low mass and small thickness, using gas gaps of at least a few hundred micrometers. Our tests with these devices demonstrate a spatial resolution of about 1 mm. We intend to make PPS devices with much smaller cells and the potential for much finer position resolutions. Our PPS tests also show response times of several nanoseconds. We report here our results in detecting betas, cosmic-ray muons, and our first proton beam tests.

  15. Material Flow and Oxide Particle Distributions in Friction-Stir Welded F/M-ODS Sheets

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Suk Hoon; Noh, Sanghoon; Jin, Hyun Ju; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    It is well known that uniform nano-oxide dispersoids act as pinning points to obstruct dislocation and grain boundary motion in ODS(Oxide dispersion strengthened) steel. However, these advantages will disappear while the material is subjected to the high temperature of conventional fusion welding. There is only limited literature available on the joining of ODS steels. Friction stir welding (FSW) is considered to be the best welding technique for welding ODS steels as the technique helps in retaining the homogeneous nano-oxide particles distributions in matrix. FSW is a solid.state, hot.shear joining process in which a rotating tool with a shoulder and terminating in a threaded pin, moves along the butting surfaces of two rigidly clamped plates placed on a backing plate. Heat generated by friction at the shoulder and to a lesser extent at the pin surface, softens the material being welded. Severe plastic deformation and flow of this plasticised metal occurs as the tool is translated along the welding direction. Material is transported from the front of the tool to the trailing edge where it is forged into a joint. Friction stir welding appears to be a very promising technique for the welding of FMS and ODS steels. This study found that, during FSW, the forward movement of the tool pin results in loose contact between the tool pin and the receding material on the advancing side.

  16. Particle-in-Cell/Test-Particle Simulations of Technological Plasmas: Sputtering Transport in Capacitive Radio Frequency Discharges

    CERN Document Server

    Trieschmann, Jan; Mussenbrock, Thomas

    2016-01-01

    The paper provides a tutorial to the conceptual layout of a self-consistently coupled Particle-In-Cell/Test-Particle model for the kinetic simulation of sputtering transport in capacitively coupled plasmas at low gas pressures. It explains when a kinetic approach is actually needed and which numerical concepts allow for the inherent nonequilibrium behavior of the charged and neutral particles. At the example of a generic sputtering discharge both the fundamentals of the applied Monte Carlo methods as well as the conceptual details in the context of the sputtering scenario are elaborated on. Finally, two in the context of sputtering transport simulations often exploited assumptions, namely on the energy distribution of impinging ions as well as on the test particle approach, are validated for the proposed example discharge.

  17. Particle acceleration at shock waves: particle spectrum as a function of the equation of state of the shocked plasma

    CERN Document Server

    Morlino, G; Vietri, M

    2007-01-01

    We determine the spectrum of particles accelerated at shocks with arbitrary speed and arbitrary scattering properties for different choices of the equation of state of the downstream plasma. More specifically we consider the effect of energy exchange between the electron and proton thermal components downstream, and the effect of generation of a turbulent magnetic field in the downstream plasma. The slope of the spectrum turns out to be appreciably affected by all these phenomena, especially in the Newtonian and trans-relativistic regime, while in the ultra-relativistic limit the universal spectrum $s\\approx 4.3$ seems to be a very solid prediction.

  18. Complex plasmas and colloidal dispersions particle-resolved studies of classical liquids and solids

    CERN Document Server

    Ivlev, Alexei; Morfill, Gregor; Royall, C. Patrick

    2012-01-01

    Complex plasmas and colloidal dispersions represent different states of soft matter. They are complementary in many ways, with the most important being that complex plasmas are virtually undamped at the particle timescales, whereas colloidal dispersions are overdamped and therefore can be brought into equilibrium in a very controlled manner. Otherwise, both fields have similar advantages: fully resolved 3D particle trajectories can easily be visualized, the pair interactions are tunable, and particles can be manipulated individually or collectively. These unique properties allow us to investigate generic processes occurring in liquids or solids at the most fundamental individual particle level. The principal research topics to be addressed in the book include: particle dynamics in liquids, with the emphasis on mesoscopic processes in the supercooled (glassy) state, e.g. dynamical heterogeneity, phase transitions in solids, with particular attention to the evolutionary paths of crystal structure development an...

  19. Measuring Collisionless Damping in Heliospheric Plasmas using Field-Particle Correlations

    CERN Document Server

    Klein, Kristopher G

    2016-01-01

    An innovative field-particle correlation technique is proposed that uses single-point measurements of the electromagnetic fields and particle velocity distribution functions to investigate the net transfer of energy from fields to particles associated with the collisionless damping of turbulent fluctuations in weakly collisional plasmas, such as the solar wind. In addition to providing a direct estimate of the local rate of energy transfer between fields and particles, it provides vital new information about the distribution of that energy transfer in velocity space. This velocity-space signature can potentially be used to identify the dominant collisionless mechanism responsible for the damping of turbulent fluctuations in the solar wind. The application of this novel field-particle correlation technique is illustrated using the simplified case of the Landau damping of Langmuir waves in an electrostatic 1D-1V Vlasov-Poisson plasma, showing that the procedure both estimates the local rate of energy transfer f...

  20. On the signature of positively charged dust particles on plasma irregularities in the mesosphere

    Science.gov (United States)

    Mahmoudian, A.; Scales, W. A.

    2013-11-01

    Recent rocket payloads have studied the properties of aerosol particles within the ambient plasma environment in the polar mesopause region and measured the signature of the positively charged particles with number densities of (2000 cm-3) for particles of 0.5-1 nm in radius. The measurement of significant numbers of positively charged aerosol particles is unexpected from the standard theory of aerosol charging in plasma. Nucleation on the cluster ions is one of the most probable hypotheses for the positive charge on the smallest particles. This work attempts to study the correlation and anti-correlation of fluctuations in the electron and ion densities in the background plasma by adopting the proposed hypothesis of positive dust particle formation. The utility being that it may provide a test for determining the presence of positive dust particles. The results of the model described show good agreement with observed rocket data. As an application, the model is also applied to investigate the electron irregularity behavior during radiowave heating assuming the presence of positive dust particles. It is shown that the positive dust produces important changes in the behavior during Polar Mesospheric Summer Echo PMSE heating experiments that can be described by the fluctuation correlation and anti-correlation properties.

  1. Anisotropic oxygen plasma etching of colloidal particles in electrospun fibers.

    Science.gov (United States)

    Ding, Tao; Tian, Ye; Liang, Kui; Clays, Koen; Song, Kai; Yang, Guoqiang; Tung, Chen-Ho

    2011-02-28

    Oxygen plasma etching of electrospun polymer fibers containing spherical colloids is presented as a new approach towards anisotropic colloidal nanoparticles. The detailed morphology of the resulting nanoparticles can be precisely controlled in a continuous way. The same approach is also amenable to prepare inorganic nanoparticles with double-sided patches.

  2. Surface nitridation of silicon nano-particles using double multi-hollow discharge plasma CVD

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, Giichiro; Yamamoto, Kosuke; Kawashima, Yuki; Sato, Muneharu; Nakahara, Kenta; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu [Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka (Japan); Kamataki, Kunihiro [Center for Reserch and Advancement in Higher Education, Kyushu University, Fukuoka (Japan); Kondo, Michio [National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki (Japan)

    2011-10-15

    We present production of silicon nano-particles and their surface nitridation for efficient multiple-exciton generation. Nitridated silicon nano-particles were produced using double multi-hollow discharge plasma CVD, where generation of silicon particles and their nitridation were independently performed using SiH{sub 4}/H{sub 2} and N{sub 2} multi-hollow discharge plasmas. We succeeded in controlling nitrogen content in a silicon nano-particle by varying a number density of N radicals irradiated to the Si particle. We also observed strong photoluminescence (PL) emission around 300-500 nm from silicon nano-particles, where the PL peak energy is about 2.5 and 3.1 eV for pure Si nano-particles, and 2.5, 3.1, and 4.1 eV for nitridated Si nano-particles. The additional UV-peak of 4.1 eV from nitridated Si particles is closely related to the nitridation surface layer on Si nano-particles (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. O+ ion conic and plasma sheet dynamics observed by Van Allen Probe satellites during the 1 June 2013 magnetic storm

    Science.gov (United States)

    Burke, W. J.; Erickson, P. J.; Yang, J.; Foster, J.; Wygant, J.; Reeves, G.; Kletzing, C.

    2016-05-01

    The Van Allen Probe satellites were near apogee in the late evening local time sector during the 1 June 2013 magnetic storm's main phase. About an hour after crossing the ring current's "nose structure" into the plasma sheet, the satellites encountered a quasiperiodic sequence of 0.08-3 keV O+ ions. Pitch angle distributions of this population consistently peaked nearly antiparallel to the local magnetic field. We interpret this population as O+ conics originating in the northern ionosphere. Sequences began as fairly steady state conic fluxes with energies in the ~ 80 to 100 eV range. Over about a half hour buildup phase, O+ energies peaked near 1 keV. During subsequent release phases lasting ~ 20 min, O+ energies returned to low-energy starting points. We argue these observations reflect repeated formations and dissolutions of downward, magnetically aligned electric fields (ɛ||) layers trapping O+ conics between mirror points within heating layers below and electrostatic barriers above. Nearly identical variations were observed at the locations of both satellites during 9 of these 13 conic cycles. Phase differences between cycles were observed at both spacecraft during the remaining events. Most "buildup" to "release" phase transitions coincided with AL index minima. However, in situ magnetometer measurements indicate only weak dipolarizations of tail-like magnetic fields. The lack of field-aligned reflected O+ and tail-like magnetic fields suggest that both ionospheres may be active. However, Southern Hemisphere origin conics cannot be observed since they would be isotropized and accelerated during neutral sheet crossings.

  4. Numerical Modeling of an RF Argon-Silane Plasma with Dust Particle Nucleation and Growth

    Science.gov (United States)

    Girshick, Steven; Agarwal, Pulkit

    2012-10-01

    We have developed a 1-D numerical model of an RF argon-silane plasma in which dust particles nucleate and grow. This model self-consistently couples a plasma module, a chemistry module and an aerosol module. The plasma module solves population balance equations for electrons and ions, the electron energy equation under the assumption of a Maxwellian velocity distribution, and Poisson's equation for the electric field. The chemistry module treats silane dissociation and reactions of silicon hydrides containing up to two silicon atoms. The aerosol module uses a sectional method to model particle size and charge distributions. The nucleation rate is equated to the rates of formation of anions containing two Si atoms, and a heterogeneous reaction model is used to model particle surface growth. Aerosol effects considered include particle charging, coagulation, and particle transport by neutral drag, ion drag, electric force, gravity and Brownian diffusion. Simulation results are shown for the case of a 13.56 MHz plasma at a pressure of 13 Pa and applied RF voltage of 100 V (amplitude), with flow through a showerhead electrode. These results show the strong coupling between the plasma and the spatiotemporal evolution of the nanoparticle cloud.

  5. Thorium colloid analysis by single particle inductively coupled plasma-mass spectrometry.

    Science.gov (United States)

    Degueldre, C; Favarger, P-Y

    2004-04-19

    Thorium colloid analysis in water has been carried out by a single particle mode using inductively coupled plasma mass spectrometry (ICP-MS). The flash of ions due to the ionisation of a thorium colloidal particle in the plasma torch can be detected and measured in a time scan for (232)Th (+ ) or (248)[ThO] (+ ) according to the sensitivity required by the mass spectrometer. The peaks of the recorded intensity of the MS signal can be analysed as a function of the particle size or fraction of the studied element in the colloid phase. The frequency of the flashes is directly proportional to the concentration of particles in the colloidal suspension. After discussing Th colloid detection, on the basis of the intensity of the ion flashes generated in the plasma torch, tests were performed on thorium dioxide colloidal particles. This feasibility study also describes the experimental conditions and the limitation of the plasma design to detect thorium colloids in a single particle analysis mode down to about 10fg.

  6. Particle Transport in ECRH Plasmas of the TJ-II; Transporte de Particulas en Plasmas ECRH del TJ-II

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, V. I.; Lopez-Bruna, D.; Estrada, T.; Guasp, J.; Reynolds, J. M.; Velasco, J. L.; Herranz, J.

    2007-07-01

    We present a systematic study of particle transport in ECRH plasmas of TJ-II with different densities. The goal is to fi nd particle confinement time and electron diffusivity dependence with line-averaged density. The experimental information consists of electron temperature profiles, T{sub e} (Thomson Scattering TS) and electron density, n{sub e}, (TS and reflectometry) and measured puffing data in stationary discharges. The profile of the electron source, Se, was obtained by the 3D Monte-Carlo code EIRENE. The analysis of particle balance has been done by linking the results of the code EIRENE with the results of a model that reproduces ECRH plasmas in stationary conditions. In the range of densities studied (0.58 {<=}n{sub e}> (10{sup 1}9m{sup -}3) {<=}0.80) there are two regions of confinement separated by a threshold density, {approx}0.65 10{sup 1}9m{sup -}3. Below this threshold density the particle confinement time is low, and vice versa. This is reflected in the effective diffusivity, D{sub e}, which in the range of validity of this study, 0.5 <{rho}<0.9 being {rho} normalized plasma radius, decreased significantly above the threshold density. The profiles of D{sub e} are flat for {>=}0,63(10{sup 1}9m{sup -}3). (Author) 35 refs.

  7. Novel fragmentation model for pulverized coal particles gasification in low temperature air thermal plasma

    Directory of Open Access Journals (Sweden)

    Jovanović Rastko D.

    2016-01-01

    Full Text Available New system for start-up and flame support based on coal gasification by low temperature air thermal plasma is planned to supplement current heavy oil system in Serbian thermal power plants in order to decrease air pollutions emission and operational costs. Locally introduced plasma thermal energy heats up and ignites entrained coal particles, thus starting chain process which releases heat energy from gasified coal particles inside burner channel. Important stages during particle combustion, such as particle devolatilisation and char combustion, are described with satisfying accuracy in existing commercial CFD codes that are extensively used as powerful tool for pulverized coal combustion and gasification modeling. However, during plasma coal gasification, high plasma temperature induces strong thermal stresses inside interacting coal particles. These stresses lead to “thermal shock” and extensive particle fragmentation during which coal particles with initial size of 50-100 m disintegrate into fragments of at most 5-10 m. This intensifies volatile release by a factor 3-4 and substantially accelerates the oxidation of combustible matter. Particle fragmentation, due to its small size and thus limited influence on combustion process is commonly neglected in modelling. The main focus of this work is to suggest novel approach to pulverized coal gasification under high temperature conditions and to implement it into commercial comprehensive code ANSYS FLUENT 14.0. Proposed model was validated against experimental data obtained in newly built pilot scale D.C plasma burner test facility. Newly developed model showed very good agreement with experimental results with relative error less than 10%, while the standard built-in gasification model had error up to 25%.

  8. Programmable physical parameter optimization for particle plasma simulations

    Science.gov (United States)

    Ragan-Kelley, Benjamin; Verboncoeur, John; Lin, Ming-Chieh

    2012-10-01

    We have developed a scheme for interactive and programmable optimization of physical parameters for plasma simulations. The simulation code Object-Oriented Plasma Device 1-D (OOPD1) has been adapted to a Python interface, allowing sophisticated user or program interaction with simulations, and detailed numerical analysis via numpy. Because the analysis/diagnostic interface is the same as the input mechanism (the Python programming language), it is straightforward to optimize simulation parameters based on analysis of previous runs and automate the optimization process using a user-determined scheme and criteria. An example use case of the Child-Langmuir space charge limit in bipolar flow is demonstrated, where the beam current is iterated upon by measuring the relationship of the measured current and the injected current.

  9. Tail reconnection region versus auroral activity inferred from conjugate ARTEMIS plasma sheet flow and auroral observations

    Science.gov (United States)

    Nishimura, Y.; Lyons, L. R.; Xing, X.; Angelopoulos, V.; Donovan, E. F.; Mende, S. B.; Bonnell, J. W.; Auster, U.

    2013-09-01

    sheet flow bursts have been suggested to correspond to different types of auroral activity, such as poleward boundary intensifications (PBIs), ensuing auroral streamers, and substorms. The flow-aurora association leads to the important question of identifying the magnetotail source region for the flow bursts and how this region depends on magnetic activity. The present study uses the ARTEMIS spacecraft coordinated with conjugate ground-based auroral imager observations to identify flow bursts beyond 45 RE downtail and corresponding auroral forms. We find that quiet-time flows are directed dominantly earthward with a one-to-one correspondence with PBIs. Flow bursts during the substorm recovery phase and during steady magnetospheric convection (SMC) periods are also directed earthward, and these flows are associated with a series of PBIs/streamers lasting for tens of minutes with similar durations to that of the series of earthward flows. Presubstorm onset flows are also earthward and associated with PBIs/streamers. The earthward flows during those magnetic conditions suggest that the flow bursts, which lead to PBIs and streamers, originate from further downtail of ARTEMIS, possibly from the distant-tail neutral line (DNL) or tailward-retreated near-Earth neutral line (NENL) rather than from the nominal NENL location in the midtail. We find that tailward flows are limited primarily to the substorm expansion phase. They continue throughout the period of auroral poleward expansion, indicating that the expansion-phase flows originate from the NENL and that NENL activity is closely related to the auroral expansion of the substorm expansion phase.

  10. Hydrogen Ionic Plasma and Particle Dynamics in Negative Ion Source for NBI

    Science.gov (United States)

    Tsumori, Katsuyoshi

    2013-10-01

    Three negative-ion-based neutral beam injectors (NBIs) have been developed for plasma heating in the Large Helical Device. The NBIs achieve successfully the nominal injection power and beam energy, and understanding of the production and transport mechanisms of H- ion is required to obtain more stable high power beam. In the ion source development, we have found hydrogen ionic plasmas with extremely low electron density are produced in the beam extraction region. The plasma is measured with a combination of an electrostatic probe, millimeter-wave interferometer and cavity ring down (CRD). It has been observed for the first time that the charge neutrality of the ionic plasma is broken with H- extraction and electrons compensate the extracted H- charge. The influence of the extraction field widely affects to the ionic plasma in the extraction region. Two-dimensional particle-in-cell simulation (2D-PIC) has been applied to investigate the particle transport and reproduces the production of the ionic plasma and electron compensation due to H- extraction. In particle model, produced H- ions leave from the Cs covered PG surface in opposite direction to beam extraction. The direction can be changed with the electric field and collective effect due to the presence of plasma. A new technique using CCD camera with H α filter applied to measure the two-dimensional distribution of H- density. In the ionic plasma, H α light is emitted via electron-impact excitation and mutual neutralization processes with H- ion and proton. Comparing the results obtained with optical emission spectroscopy, electrostatic probe and CRD, it is shown the H α emission is dominated with the mutual neutralization. By subtracting the CCD images with and without beam extraction, it becomes clear that H- ions are extracted not directly from the PG surface but from the bulk of the ionic plasma. The result suggests the initial energy of H- ion is dumped rapidly in the ionic plasma.

  11. On the role of wave-particle interactions in the macroscopic dynamics of collisionless plasmas

    CERN Document Server

    Wilson, Lynn B; Osmane, Adnane; Malaspina, David M

    2015-01-01

    What is the relative importance of small-scale (i.e., electron to sub-electron scales), microphysical plasma processes to the acceleration of particles from thermal to suprathermal or even to cosmic-ray energies? Additionally, can these microphysical plasma processes influence or even dominate macroscopic (i.e., greater than ion scales) processes, thus affecting global dynamics? These are fundamental and unresolved questions in plasma and astrophysical research. Recent observations of large amplitude electromagnetic waves in the terrestrial radiation belts [i.e., Cattell et al., 2008; Kellogg et al., 2010; Wilson III et al., 2011] and in collisionless shock waves [i.e., Wilson III et al., 2014a,b] have raised questions regarding the macrophysical effect of these microscopic waves. The processes thought to dominate particle acceleration and the macroscopic dynamics in both regions have been brought into question with these recent observations. The relative importance of wave-particle interactions has recently ...

  12. Damaging impacts of energetic charge particles on materials in plasma energy explosive events

    Institute of Scientific and Technical Information of China (English)

    Deng Bai-Quan; Peng Li-Lin; Yan Jian-Cheng; Luo Zheng-Ming; Chen Zhi

    2006-01-01

    To provide some reference data for estimation of the erosion rates and lifetimes of some candidate plasma facing component (PF3 materials in the plasma stored energy explosive events (PSEEE), this paper calculates the sputtering yields of Mo, W and deuterium saturated Li surface bombarded by energetic charged particles by a new sputtering physics description method based on bipartition model of charge particle transport theory. The comparisons with Monte Carlo data of TRIM code and experimental results are made. The dependences of maximum energy deposition,particle and energy reflection coefficients on the incident energy of energetic runaway electrons impinging on the different material surfaces are also calculated. Results may be useful for estimating the lifetime of PFC and analysing the impurity contamination extent, especially in the PSEEE for high power density and with high plasma current fusion reactor.

  13. Mitigating Particle Integration Error in Relativistic Laser-Plasma Simulations

    Science.gov (United States)

    Higuera, Adam; Weichmann, Kathleen; Cowan, Benjamin; Cary, John

    2016-10-01

    In particle-in-cell simulations of laser wakefield accelerators with a0 greater than unity, errors in particle trajectories produce incorrect beam charges and energies, predicting performance not realized in experiments such as the Texas Petawatt Laser. In order to avoid these errors, the simulation time step must resolve a time scale smaller than the laser period by a factor of a0. If the Yee scheme advances the fields with this time step, the laser wavelength must be over-resolved by a factor of a0 to avoid dispersion errors. Here is presented and demonstrated with Vorpal simulations, a new electromagnetic algorithm, building on previous work, correcting Yee dispersion for arbitrary sub-CFL time steps, reducing simulation times by a0.

  14. Implementations of mesh refinement schemes for particle-in-cell plasma simulations

    Energy Technology Data Exchange (ETDEWEB)

    Vay, J.-L.; Colella, P.; Friedman, A.; Grote, D.P.; McCorquodale, P.; Serafini, D.B.

    2003-10-20

    Plasma simulations are often rendered challenging by the disparity of scales in time and in space which must be resolved. When these disparities are in distinctive zones of the simulation region, a method which has proven to be effective in other areas (e.g. fluid dynamics simulations) is the mesh refinement technique. We briefly discuss the challenges posed by coupling this technique with plasma Particle-In-Cell simulations and present two implementations in more detail, with examples.

  15. Self-modulated dynamics of a relativistic charged particle beam in plasma wake field excitation

    Energy Technology Data Exchange (ETDEWEB)

    Akhter, T.; Fedele, R. [Dipartimento di Fisica ‘Ettore Pancini’, Università di Napoli Federico II and INFN Sezione di Napoli, Napoli (Italy); Nicola, S. De [CNR-SPIN and INFN Sezione di Napoli, Napoli (Italy); Tanjia, F. [Dipartimento di Fisica ‘Ettore Pancini’, Università di Napoli Federico II and INFN Sezione di Napoli, Napoli (Italy); Jovanović, D. [Institute of Physics, University of Belgrade, Belgrade (Serbia); Mannan, A. [Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh)

    2016-09-01

    The self-modulated dynamics of a relativistic charged particle beam is provided within the context of the theory of plasma wake field excitation. The self-consistent description of the beam dynamics is provided by coupling the Vlasov equation with a Poisson-type equation relating the plasma wake potential to the beam density. An analysis of the beam envelope self-modulation is then carried out and the criteria for the occurrence of the instability are discussed thereby.

  16. Plasma etching of polystyrene latex particles for the preparation of graphene oxide nanowalls

    Directory of Open Access Journals (Sweden)

    Bon Bittolo Silvia

    2012-01-01

    Full Text Available Graphene oxide nanowalls were prepared by casting a water dispersion of polystyrene latex particles onto a graphene oxide film followed by tetrafluoromethane plasma etching. Mild plasma etching conditions allow one to retain the oxygen functional groups on the graphene oxide nanowalls. It was found that the exposure to a xenon light source of such graphene oxide nanowalls coated with a gold thin film results in an increase of the electrical conductivity.

  17. HIDENEK: An implicit particle simulation of kinetic-MHD phenomena in three-dimensional plasmas

    Science.gov (United States)

    Tanaka, Motohiko

    1993-05-01

    An advanced 'kinetic-MHD' simulation method and its applications to plasma physics are given in this lecture. This method is quite stable for studying strong nonlinear, kinetic processes associated with large space-scale, low-frequency electromagnetic phenomena of plasmas. A full set of the Maxwell equations, and the Newton-Lorentz equations of motion for particle ions and guiding-center electrons are adopted. In order to retain only the low-frquency waves and instabilities, implicit particle-field equations are derived. The present implicit-particle method is proved to reproduce the MHD eigenmodes such as Alfven, magnetosonic and kinetic Alfven waves in a thermally near-equilibrium plasma. In the second part of the lecture, several physics applications are shown. These include not only the growth of the instabilities of beam ions against the background plasmas and helical link of the current, but they also demonstrate nonlinear results such as pitch-angle scattering of the ions. Recent progress in the simulation of the Kelvin-Helmholtz instability is also presented with a special emphasis on the mixing of the plasma particles.

  18. Observation of an Extremely Large-Density Heliospheric Plasma Sheet Compressed by an Interplanetary Shock at 1 AU

    Science.gov (United States)

    Wu, Chin-Chun; Liou, Kan; Lepping, R. P.; Vourlidas, Angelos; Plunkett, Simon; Socker, Dennis; Wu, S. T.

    2017-08-01

    At 11:46 UT on 9 September 2011, the Wind spacecraft encountered an interplanetary (IP) fast-forward shock. The shock was followed almost immediately by a short-duration (˜ 35 minutes) extremely dense pulse (with a peak ˜ 94 cm-3). The pulse induced an extremely large positive impulse (SYM-H = 74 nT and Dst = 48 nT) on the ground. A close examination of other in situ parameters from Wind shows that the density pulse was associated with i) a spike in the plasma β (ratio of thermal to magnetic pressure), ii) multiple sign changes in the azimuthal component of the magnetic field (B_{φ}), iii) a depressed magnetic field magnitude, iv) a small radial component of the magnetic field, and v) a large (> 90°) change in the suprathermal (˜ 255 eV) electron pitch angle across the density pulse. We conclude that the density pulse is associated with the heliospheric plasma sheet (HPS). The thickness of the HPS is estimated to be {˜} 8.2×105 km. The HPS density peak is about five times the value of a medium-sized density peak inside the HPS (˜ 18 cm-3) at 1 AU. Our global three-dimensional magnetohydrodynamic simulation results (Wu et al. in J. Geophys. Res. 212, 1839, 2016) suggest that the extremely large density pulse may be the result of the compression of the HPS by an IP shock crossing or an interaction between an interplanetary shock and a corotating interaction region.

  19. Quasi-two-dimensional complex plasma containing spherical particles and their binary agglomerates

    CERN Document Server

    Chaudhuri, M; Nosenko, V; Thomas, H M

    2015-01-01

    A new type of quasi-two-dimensional complex plasma system was observed which consisted of monodisperse microspheres and their binary agglomerations (dimers). The particles and their dimers levitated in a plasma sheath at slightly different heights and formed two distinct sublayers. The sys- tem did not crystallize and may be characterized as disordered solid. The dimers were identified based on their characteristic appearance in defocused images, i.e., rotating interference fringe pat- terns. The in-plane and inter-plane particle separations exhibit nonmonotonic dependence on the discharge pressure which agrees well with theoretical predictions.

  20. Photons and particles emitted from cold atmospheric-pressure plasma inactivate bacteria and biomolecules independently and synergistically.

    Science.gov (United States)

    Lackmann, Jan-Wilm; Schneider, Simon; Edengeiser, Eugen; Jarzina, Fabian; Brinckmann, Steffen; Steinborn, Elena; Havenith, Martina; Benedikt, Jan; Bandow, Julia E

    2013-12-06

    Cold atmospheric-pressure plasmas are currently in use in medicine as surgical tools and are being evaluated for new applications, including wound treatment and cosmetic care. The disinfecting properties of plasmas are of particular interest, given the threat of antibiotic resistance to modern medicine. Plasma effluents comprise (V)UV photons and various reactive particles, such as accelerated ions and radicals, that modify biomolecules; however, a full understanding of the molecular mechanisms that underlie plasma-based disinfection has been lacking. Here, we investigate the antibacterial mechanisms of plasma, including the separate, additive and synergistic effects of plasma-generated (V)UV photons and particles at the cellular and molecular levels. Using scanning electron microscopy, we show that plasma-emitted particles cause physical damage to the cell envelope, whereas UV radiation does not. The lethal effects of the plasma effluent exceed the zone of physical damage. We demonstrate that both plasma-generated particles and (V)UV photons modify DNA nucleobases. The particles also induce breaks in the DNA backbone. The plasma effluent, and particularly the plasma-generated particles, also rapidly inactivate proteins in the cellular milieu. Thus, in addition to physical damage to the cellular envelope, modifications to DNA and proteins contribute to the bactericidal properties of cold atmospheric-pressure plasma.

  1. Detection of electromagnetic pulses produced by hypervelocity micro particle impact plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Close, Sigrid; Lee, Nicolas; Johnson, Theresa; Goel, Ashish; Fletcher, Alexander [Department of Aeronautics and Astronautics, Stanford University, Stanford, California 94305 (United States); Linscott, Ivan; Strauss, David; Lauben, David [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Srama, Ralf; Mocker, Anna; Bugiel, Sebastian [Institut für Raumfahrtsysteme, Universität Stuttgart, Pfaffenwaldring 29, 70569 Stuttgart (Germany)

    2013-09-15

    Hypervelocity micro particles (mass < 1 ng), including meteoroids and space debris, routinely impact spacecraft and produce plasmas that are initially dense (∼10{sup 28} m{sup −3}), but rapidly expand into the surrounding vacuum. We report the detection of radio frequency (RF) emission associated with electromagnetic pulses (EMPs) from hypervelocity impacts of micro particles in ground-based experiments using micro particles that are 15 orders of magnitude less massive than previously observed. The EMP production is a stochastic process that is influenced by plasma turbulence such that the EMP detection rate that is strongly dependent on impact speed and on the electrical charge conditions at the impact surface. In particular, impacts of the fastest micro particles occurring under spacecraft charging conditions representative of high geomagnetic activity are the most likely to produce RF emission. This new phenomenon may provide a source for unexplained RF measurements on spacecraft charged to high potentials.

  2. Self-organization and oscillation of negatively charged dust particles in a 2-dimensional dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Song, Y.L. [College of Science, China Agricultural University, Beijing 100083 (China); Huang, F., E-mail: huangfeng@cau.edu.cn [College of Science, China Agricultural University, Beijing 100083 (China); Chen, Z.Y., E-mail: chenzy@mail.buct.edu.cn [Department of Physics, Beijing University of Chemical Technology, Beijing 100029 (China); State Key Laboratory of Laser Propulsion & Application, Beijing 101416 (China); Liu, Y.H. [School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025 (China); Yu, M.Y. [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Institute for Theoretical Physics I, Ruhr University, D-44801 Bochum (Germany)

    2016-02-22

    Negatively charged dust particles immersed in 2-dimensional dusty plasma system are investigated by molecular dynamics simulations. The effects of the confinement potential and attraction interaction potential on dust particle self-organization are studied in detail and two typical dust particle distributions are obtained when the system reaches equilibrium. The average radial velocity (ARV), average radial force (ARF) and radial mean square displacement are employed to analyze the dust particles' dynamics. Both ARVs and ARFs exhibit oscillation behaviors when the simulation system reaches equilibrium state. The relationships between the oscillation and confinement potential and attraction potential are studied in this paper. The simulation results are qualitatively similar to experimental results. - Highlights: • Self-organization and oscillation of a 2-dimensional dusty plasma is investigated. • Effect of the confinement potential on dust self-organization and oscillation is given. • Effect of the attraction potential on dust self-organization and oscillation is studied.

  3. Stopping power and polarization induced in a plasma by a fast charged particle in circular motion

    Energy Technology Data Exchange (ETDEWEB)

    Villo-Perez, Isidro [Departamento de Electronica, Tecnologia de las Computadoras y Proyectos, Universidad Politecnica de Cartagena, Cartagena (Spain); Arista, Nestor R. [Division Colisiones Atomicas, Centro Atomico Bariloche and Instituto Balseiro, Comision Nacional de Energia Atomica, Bariloche (Argentina); Garcia-Molina, Rafael [Departamento de Fisica, Universidad de Murcia, Murcia (Spain)

    2002-03-28

    We describe the perturbation induced in a plasma by a charged particle in circular motion, analysing in detail the evolution of the induced charge, the electrostatic potential and the energy loss of the particle. We describe the initial transitory behaviour and the different ways in which convergence to final stationary solutions may be obtained depending on the basic parameters of the problem. The results for the stopping power show a resonant behaviour which may give place to large stopping enhancement values as compared with the case of particles in straight-line motion with the same linear velocity. The results also explain a resonant effect recently obtained for particles in circular motion in magnetized plasmas. (author)

  4. Particle melting, flattening, and stacking behaviors in induction plasma deposition of tungsten

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Particle melting, flattening, and stacking behaviors during induction plasma deposition of refractory tungsten were studied for land-based turbine engine application. Scanning electron microscopy was used to observe the morphology of particles and splats as well as to examine the microstructure of tungsten deposit. Three kinds of pores were found in the deposit, i.e., large pores with d > 10 μm, medium pores in the range of 1~10μm, and small pores with d < 1 μm. Both optimized plasma spray condition and use of spherical powder with a narrow particle size distribution are important in the elimination of large and medium pores and have significant influences on the formation of dense tungsten deposit. Highly dense tungsten deposit was obtained through complete melting, sufficiently flattening, and regularly stacking of tungsten particles.

  5. Particle Acceleration and Heating by Turbulent Reconnection

    CERN Document Server

    Vlahos, Loukas; Isliker, Heinz; Tsiolis, Vassilios; Anastasiadis, Anastasios

    2016-01-01

    Turbulent flows in the solar wind, large scale current sheets, multiple current sheets, and shock waves lead to the formation of environments in which a dense network of current sheets is established and sustains "turbulent reconnection". We constructed a 2D grid on which a number of randomly chosen grid points are acting as {\\bf scatterers} (i.e.\\ magnetic clouds or current sheets). In particular, we study how test particles respond inside this collection of scatterers. We study the energy gain of individual particles, the evolution of their energy distribution, their escape time distribution and we determine the transport coefficients from the particle dynamics. We have shown that our model describes very well the second order Fermi energization of non relativistic plasmas in open or periodic numerical boxes, when using magnetic clouds as scatterers. Replacing the "magnetic clouds" with current sheets, we have proven that the processes are much more efficient and particle heating and acceleration depends on...

  6. A Variational Formulation of Macro-Particle Algorithms for Kinetic Plasma Simulations

    Science.gov (United States)

    Shadwick, B. A.

    2013-10-01

    Macro-particle based simulations methods are in widespread use in plasma physics; their computational efficiency and intuitive nature are largely responsible for their longevity. In the main, these algorithms are formulated by approximating the continuous equations of motion. For systems governed by a variational principle (such as collisionless plasmas), approximations of the equations of motion is known to introduce anomalous behavior, especially in system invariants. We present a variational formulation of particle algorithms for plasma simulation based on a reduction of the distribution function onto a finite collection of macro-particles. As in the usual Particle-In-Cell (PIC) formulation, these macro-particles have a definite momentum and are spatially extended. The primary advantage of this approach is the preservation of the link between symmetries and conservation laws. For example, nothing in the reduction introduces explicit time dependence to the system and, therefore, the continuous-time equations of motion exactly conserve energy; thus, these models are free of grid-heating. In addition, the variational formulation allows for constructing models of arbitrary spatial and temporal order. In contrast, the overall accuracy of the usual PIC algorithm is at most second due to the nature of the force interpolation between the gridded field quantities and the (continuous) particle position. Again in contrast to the usual PIC algorithm, here the macro-particle shape is arbitrary; the spatial extent is completely decoupled from both the grid-size and the ``smoothness'' of the shape; smoother particle shapes are not necessarily larger. For simplicity, we restrict our discussion to one-dimensional, non-relativistic, un-magnetized, electrostatic plasmas. We comment on the extension to the electromagnetic case. Supported by the US DoE under contract numbers DE-FG02-08ER55000 and DE-SC0008382.

  7. Non-Gaussian properties of global momentum and particle fluxes in a cylindrical laboratory plasma

    Energy Technology Data Exchange (ETDEWEB)

    Nagashima, Yoshihiko; Yamada, Takuma [Graduate School of Frontier Sciences, University of Tokyo, Kashiwa 277-8561 (Japan); Itoh Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580 (Japan); Itoh, Sanae-I.; Inagaki, Shigeru; Fujisawa, Akihide; Yagi, Masatoshi [Itoh Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580 (Japan); Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580 (Japan); Arakawa, Hiroyuki [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga 816-8580 (Japan); Kasuya, Naohiro; Itoh, Kimitaka [Itoh Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580 (Japan); National Institute for Fusion Science, Toki 509-5292 (Japan); Kamataki, Kunihiro [Center for Research and Advancement in Higher Education, Kyushu University, Fukuoka 816-8580 (Japan); Shinohara, Shunjiro [Institute of Engineering, Tokyo University of Agriculture and Technology, Koganei 184-8588 (Japan); Oldenbuerger, Stella [Itoh Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580 (Japan); Takase, Yuichi [Graduate School of Frontier Sciences, University of Tokyo, Kashiwa 277-8561 (Japan); Diamond, Patrick H. [Itoh Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580 (Japan); Center for Astrophysics and Space Sciences, University of California San Diego, La Jolla, California 92093 (United States)

    2011-07-15

    Non-Gaussian statistical properties of the azimuthally averaged momentum and particle fluxes driven by turbulence have been simultaneously observed in inhomogeneous magnetized plasmas for the first time. We identified the stretched Gaussian distribution of the both fluxes and the transition from the point-wise distribution to averaged ones was confirmed. The change of the particle flux precedes that of the momentum flux, demonstrating that the momentum flux is induced by the relaxation of density gradient.

  8. TOPICAL REVIEW: Formation and behaviour of nano/micro-particles in low pressure plasmas

    Science.gov (United States)

    Watanabe, Y.

    2006-10-01

    Systematic studies on formation and behaviour of particles in low-pressure plasmas have been carried out in silane capacitive high-frequency-discharges developing various in situ particle growth observation methods in the range of their size above sub-nanometres. Studies on charging characteristics of the particles and forces acting on them in the plasmas have greatly contributed to progress in particle growth. All the time evolutions of particle size and density observed until now have a common feature that the particles grow to large ones of micrometres in size through three phases: the initial growth phase up to a nanometre size, the rapid growth phase and the growth saturation phase. The growth in the rapid growth and growth saturation phases can be explained fairly well by the model of coagulation between the negatively charged particles and the positively charged ones of nanometre size. While some issues are still left to be solved, the growth processes in the initial growth phase can be understood by taking into account the relationship between the gas residence time and the growth time for the particles to grow up to nanometre size.

  9. Feature-Based Analysis of Plasma-Based Particle Acceleration Data

    Energy Technology Data Exchange (ETDEWEB)

    Rubel, Oliver [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Geddes, Cameron G. R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Chen, Min [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Cormier-Michel, Estelle [Tech-X Corp., Boulder, CO (United States); Bethel, E. Wes [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-02-01

    Plasma-based particle accelerators can produce and sustain thousands of times stronger acceleration fields than conventional particle accelerators, providing a potential solution to the problem of the growing size and cost of conventional particle accelerators. To facilitate scientific knowledge discovery from the ever growing collections of accelerator simulation data generated by accelerator physicists to investigate next-generation plasma-based particle accelerator designs, we describe a novel approach for automatic detection and classification of particle beams and beam substructures due to temporal differences in the acceleration process, here called acceleration features. The automatic feature detection in combination with a novel visualization tool for fast, intuitive, query-based exploration of acceleration features enables an effective top-down data exploration process, starting from a high-level, feature-based view down to the level of individual particles. We describe the application of our analysis in practice to analyze simulations of single pulse and dual and triple colliding pulse accelerator designs, and to study the formation and evolution of particle beams, to compare substructures of a beam and to investigate transverse particle loss.

  10. Comparative analysis of the processing accuracy of high strength metal sheets by AWJ, laser and plasma

    Science.gov (United States)

    Radu, M. C.; Schnakovszky, C.; Herghelegiu, E.; Tampu, N. C.; Zichil, V.

    2016-08-01

    Experimental tests were carried out on two high-strength steel materials (Ramor 400 and Ramor 550). Quantification of the dimensional accuracy was achieved by measuring the deviations from some geometric parameters of part (two lengths and two radii). It was found that in case of Ramor 400 steel, at the jet inlet, the deviations from the part radii are quite small for all the three analysed processes. Instead for the linear dimensions, the deviations are small only in case of laser cutting. At the jet outlet, the deviations raised in small amount compared to those obtained at the jet inlet for both materials as well as for all the three processes. Related to Ramor 550 steel, at the jet inlet the deviations from the part radii are very small in case of AWJ and laser cutting but larger in case of plasma cutting. At the jet outlet, the deviations from the part radii are very small for all processes; in case of linear dimensions, there was obtained very small deviations only in the case of laser processing, the other two processes leading to very large deviations.

  11. Three-Dimensional Dust-Acoustic Waves in a Collisional Dusty Plasma with Opposite Polarity Particles

    Institute of Scientific and Technical Information of China (English)

    LIN Mai-Mai; DUAN Wen-Shan

    2005-01-01

    The dispersion relation is derived for three-dimensional dust-acoustic waves in a current-driven dusty plasmas with both positively and negatively charged dust particles. The dependencies of the frequency and the growth rate on the wave number K, the intensity of magnetic field B, and the inclination angle θ have been numerically shown in this paper. The growth rate is negative for the laboratory dusty plasma, but it is positive for the cosmic dusty plasma.It is found that when the inclination angle θ = π/2, there is no instability. The effect of the electrostatic field E0 has also been studied in this paper.

  12. Scheme for proton-driven plasma-wakefield acceleration of positively charged particles in a hollow plasma channel

    Directory of Open Access Journals (Sweden)

    Longqing Yi (易龙卿

    2013-07-01

    Full Text Available A new scheme for accelerating positively charged particles in a plasma-wakefield accelerator is proposed. If the proton drive beam propagates in a hollow plasma channel, and the beam radius is of order of the channel width, the space charge force of the driver causes charge separation at the channel wall, which helps to focus the positively charged witness bunch propagating along the beam axis. In the channel, the acceleration buckets for positively charged particles are much larger than in the blowout regime of the uniform plasma, and stable acceleration over long distances is possible. In addition, phasing of the witness with respect to the wave can be tuned by changing the radius of the channel to ensure the acceleration is optimal. Two-dimensional simulations suggest that, for proton drivers likely available in future, positively charged particles can be stably accelerated over 1 km with the average acceleration gradient of 1.3  GeV/m.

  13. Dust particles in controlled fusion devices: morphology, observations in the plasma and influence on the plasma performance

    Science.gov (United States)

    Rubel, M.; Cecconello, M.; Malmberg, J. A.; Sergienko, G.; Biel, W.; Drake, J. R.; Hedqvist, A.; Huber, A.; Philipps, V.

    2001-08-01

    The formation and release of particle agglomerates, i.e. debris and dusty objects, from plasma facing components and the impact of such materials on plasma operation in controlled fusion devices has been studied in the Extrap T2 reversed field pinch and the TEXTOR tokamak. Several plasma diagnostic techniques, camera observations and surface analysis methods were applied for in situ and ex situ investigation. The results are discussed in terms of processes that are decisive for dust transfer: localized power deposition connected with wall locked modes causing emission of carbon granules, brittle destruction of graphite and detachment of thick flaking co-deposited layers. The consequences for large next step devices are also addressed.

  14. Surface Modification of Fine Particle by Plasma Grafting in a Circulating Fluidized Bed Reactor under Reduced Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sounghee [Woosuk University, Jinchon (Korea, Republic of)

    2015-10-15

    A plasma surface modification of powders has been carried out in a circulating fluidized bed reactor under reduced pressure. Polystyrene (PS) particles treated by plasma are grafted with polyethylene glycol (PEG) on the surface. The virgin, plasma-treated and grafted powders were characterized by DPPH method, FTIR, SEM and contact angle meter. The plasma-treated PS powders have well formed peroxide on the surface, By PEG grafting polymerization, PEG is well grafted and dispersed on the surface of the plasma-treated PS powders. The PEG-g-PS particle was successfully synthesized using the plasma circulating fluidized bed reactor under reduced pressure.

  15. Micron-Sized Particles Detected in the Vicinity of Jupiter by the Voyager Plasma Wave Instruments

    Science.gov (United States)

    Tsintikidis, D.; Gurnett, D. A.; Kurth, W. S.; Granroth, L. J.

    1996-01-01

    Wideband waveform data obtained by the plasma wave instruments onboard the Voyager 1 and 2 spacecraft have been used to study micron-sized dust particles in the vicinity of Jupiter. The technique used was developed during the flybys of Saturn, Uranus, and Neptune, and makes use of the fact that a particle striking the spacecraft at 10-20 km/s causes a voltage pulse in the plasma wave receiver. The waveform of the voltage pulse is much different than the waveform of plasma waves and provides a highly reliable method of detecting micron-sized dust particles. Although the dust impact rate observed in the vicinity of Jupiter is much lower than the rates at Saturn, Uranus, and Neptune, the particles are easily detectable. Approximately 1200 48-second frames of wideband waveform data were examined in the vicinity of Jupiter. Dust impact signatures were found in approximately 20% of these frames. The peak impact rates are about 1 impact per second, and the peak number densities are about 10(exp -5) m(exp -3). Most of the impacts occurred near the equatorial plane at radial distances less than about 35 R(sub j) from Jupiter. Analysis of the detection threshold indicates that the particles have masses greater than 10(exp -11) g, which corresponds to particles with diameters of a few micrometers or larger.

  16. pTC-1 observation of ion high-speed flow reversal in the near-Earth plasma sheet during substorm

    Institute of Scientific and Technical Information of China (English)

    H.; RME; I.; DANDOURAS; C.; M.; CARR

    2008-01-01

    Based on measurements of FGM and HIA on board TC-1 at its apogee on Septem-ber 14, 2004, we analyzed the ion high-speed flows in the near-Earth plasma sheet observed during the substorm expansion phase. Strong tailward high-speed flows (Vx ~ -350 km/s) were first seen at about X ~ -13.2 RE in near-Earth magnetotail, one minute later the flows reversed from tailward to earthward. The reversal process occurred quickly after the substorm expansion onset. The near-Earth magnetotail plasma sheet was one of key regions for substorm onset. Our analysis showed that the ion flow reversal from tailward to earthward was likely to be in close relation with the substorm expansion initiation and might play an important role in trigger-ing the substorm expansion onset.

  17. Using PEACE Data from the four CLUSTER Spacecraft to Measure Compressibility, Vorticity, and the Taylor Microscale in the Magnetosheath and Plasma Sheet

    Science.gov (United States)

    Goldstein, Melvyn L.; Parks, George; Gurgiolo, C.; Fazakerley, Andrew N.

    2008-01-01

    We present determinations of compressibility and vorticity in the magnetosheath and plasma sheet using moments from the four PEACE thermal electron instruments on CLUSTER. The methodology used assumes a linear variation of the moments throughout the volume defined by the four satellites, which allows spatially independent estimates of the divergence, curl, and gradient. Once the vorticity has been computed, it is possible to estimate directly the Taylor microscale. We have shown previously that the technique works well in the solar wind. Because the background flow speed in the magnetosheath and plasma sheet is usually less than the Alfven speed, the Taylor frozen-in-flow approximation cannot be used. Consequently, this four spacecraft approach is the only viable method for obtaining the wave number properties of the ambient fluctuations. Our results using electron velocity moments will be compared with previous work using magnetometer data from the FGM experiment on Cluster.

  18. Particle-in-cell simulations of tunneling ionization effects in plasma-based accelerators

    CERN Document Server

    Bruhwiler, D L; Cary, J R; Esarey, E; Leemans, W; Giacone, R E

    2003-01-01

    Plasma-based accelerators can sustain accelerating gradients on the order of 100 GV/m. If the plasma is not fully ionized, fields of this magnitude will ionize neutral atoms via electron tunneling, which can completely change the dynamics of the plasma wake. Particle-in-cell simulations of a high-field plasma wakefield accelerator, using the OOPIC code, which includes field-induced tunneling ionization of neutral Li gas, show that the presence of even moderate neutral gas density significantly degrades the quality of the wakefield. The tunneling ionization model in OOPIC has been validated via a detailed comparison with experimental data from the l'OASIS laboratory. The properties of a wake generated directly from a neutral gas are studied, showing that one can recover the peak fields of the fully ionized plasma simulations, if the density of the electron drive bunch is increased such that the bunch rapidly ionized the gas.

  19. Solid particle erosion of plasma sprayed ceramic coatings

    Directory of Open Access Journals (Sweden)

    Branco José Roberto Tavares

    2004-01-01

    Full Text Available Thermal spraying allows the production of overlay protective coatings of a great variety of materials, almost without limitations as to its components, phases and constituents on a range of substrates. Wear and corrosion resistant coatings account for significant utilization of thermal spray processes. Besides being a means to evaluate the coating tribological performance, erosion testing allows also an assessment of the coating toughness and adhesion. Nevertheless, the relationship between the erosion behavior of thermal sprayed coatings and its microstructural features is not satisfactorily understood yet. This paper examines room temperature solid particle erosion of zirconia and alumina-based ceramic coatings, with different levels of porosity and varying microstrucutre and mechanical properties. The erosion tests were carried out by a stream of alumina particles with an average size of 50 µm at 70 m/s, carried by an air jet with impingement angle 90°. The results indicate that current erosion models based on hardness alone cannot account for experimental results, and, that there is a strong relationship between the erosion rate and the porosity.

  20. Experimental study of nonlinear interaction of plasma flow with charged thin current sheets: 1. Boundary structure and motion

    Directory of Open Access Journals (Sweden)

    E. Amata

    2006-01-01

    Full Text Available We study plasma transport at a thin magnetopause (MP, described hereafter as a thin current sheet (TCS, observed by Cluster at the southern cusp on 13 February 2001 around 20:01 UT. The Cluster observations generally agree with the predictions of the Gas Dynamic Convection Field (GDCF model in the magnetosheath (MSH up to the MSH boundary layer, where significant differences are seen. We find for the MP a normal roughly along the GSE x-axis, which implies a clear departure from the local average MP normal, a ~90 km thickness and an outward speed of 35 km/s. Two populations are identified in the MSH boundary layer: the first one roughly perpendicular to the MSH magnetic field, which we interpret as the "incident" MSH plasma, the second one mostly parallel to B. Just after the MP crossing a velocity jet is observed with a peak speed of 240 km/s, perpendicular to B, with MA=3 and β>10 (peak value 23. The magnetic field clock angle rotates by 70° across the MP. Ex is the main electric field component on both sides of the MP, displaying a bipolar signature, positive on the MSH side and negative on the opposite side, corresponding to a ~300 V electric potential jump across the TCS. The E×B velocity generally coincides with the perpendicular velocity measured by CIS; however, in the speed jet a difference between the two is observed, which suggests the need for an extra flow source. We propose that the MP TCS can act locally as an obstacle for low-energy ions (<350 eV, being transparent for ions with larger gyroradius. As a result, the penetration of plasma by finite gyroradius is considered as a possible source for the jet. The role of reconnection is briefly discussed. The electrodynamics of the TCS along with mass and momentum transfer across it are further discussed in the companion paper by Savin et al. (2006.

  1. NIFS joint research meeting on plasma facing components, PSI, and heat/particle control

    Energy Technology Data Exchange (ETDEWEB)

    Yamashina, T. [Hokkaido Univ., Sapporo (Japan)

    1997-10-01

    The LHD collaboration has been started in 1996. Particle and heat control is one of the categories for the collaboration, and a few programs have been nominated in these two years. A joint research meeting on PFC, PSI, heat and particle meeting was held at NIFS on June 27, 1997, in which present status of these programs were reported. This is a collection of the notes and view graphs presented in this meeting. Brief reviews and research plan of each program are included in relation to divertor erosion and sputtering, impurity generation, hydrogen recycling, edge plasma structure, edge transport and its control, heat removal, particle exhaust, wall conditioning etc. (author)

  2. The current of a particle along a microtubule in microscopic plasma

    Energy Technology Data Exchange (ETDEWEB)

    Li Wei [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, Guangdong 510006 (China); Chen Junfang [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, Guangdong 510006 (China)], E-mail: tolwwt@163.com; Wang Teng [School of Computer, South China Normal University, 510006 Guangzhou (China); Lai Xiuqiong [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, Guangdong 510006 (China)

    2008-09-01

    Transport of a particle along the axis of a microtubule in a plasma-enhanced chemical vapor deposition (PECVD) system is investigated. The current, respectively, as a function of the temperature, the magnetic field and the external force is obtained. The value and direction of the current may be controlled by changing the above parameters.

  3. Dynamic interaction potential and the scattering cross sections of the semiclassical plasma particles

    Energy Technology Data Exchange (ETDEWEB)

    Dzhumagulova, K. N.; Shalenov, E. O.; Gabdullina, G. L. [IETP, Al Farabi Kazakh National University, 71al Farabi Street, Almaty 050040 (Kazakhstan)

    2013-04-15

    The dynamic model of the charged particles interaction in non-ideal semiclassical plasma is presented. This model takes into account the quantum mechanical diffraction effect and the dynamic screening effect. On the basis of the dynamic interaction potential, the electron scattering cross sections are investigated. Comparison with the results obtained on the basis of other models and conclusions were made.

  4. Plume expansion of a laser-induced plasma studied with the particle-in-cell method

    DEFF Research Database (Denmark)

    Ellegaard, Ole; Nedela, T; Urbassek, H;

    2002-01-01

     The initial stage of laser-induced plasma plume expansion from a solid in vacuum and the effect of the Coulomb field have been studied. We have performed a one-dimensional numerical calculation by mapping the charge on a computational grid according to the particle-in-cell (PIC) method of Birdsall...

  5. Plume expansion of a laser-induced plasma studied with the particle-in-cell method

    DEFF Research Database (Denmark)

    Ellegaard, O.; Nedelea, T.; Schou, Jørgen;

    2002-01-01

    The initial stage of laser-induced plasma plume expansion from a solid in vacuum and the effect of the Coulomb field have been studied. We have performed a one-dimensional numerical calculation by mapping the charge on a computational grid according to the particle-in-cell (PIC) method of Birdsall...

  6. Differences between real and particle-in-cell plasmas: effects of coarse-graining

    CERN Document Server

    Melzani, Mickaël; Folini, Doris; Winisdoerffer, Christophe

    2013-01-01

    The PIC model relies on two building blocks. The first stems from the capability of computers to handle only up to $\\sim10^{10}$ particles, while real plasmas contain from $10^4$ to $10^{20}$ particles per Debye sphere: a coarse-graining step must be used, whereby of the order of $p\\sim10^{10}$ real particles are represented by a single computer superparticle. The second is field storage on a grid with its subsequent finite superparticle size. We introduce the notion of coarse-graining dependent quantities, i.e. physical quantities depending on the number $p$. They all derive from the plasma parameter $\\Lambda$, which we show to be proportional to $1/p$. We explore three examples: the rapid collision- and fluctuation-induced thermalization of plasmas with different temperatures, that scale with the number of superparticles per grid cell and are a factor $p\\sim10^{10}$ faster than in real plasmas; the high level of electrostatic fluctuations in a thermal plasma, with corrections due to the finite superparticle...

  7. Numerical simulation of charging of an absorbing sphere in collisionless plasmas: asymptotics and trapped particle dynamics.

    Science.gov (United States)

    Kiselyov, Alexander; Dolgonosov, Maxim; Krasovsky, Victor

    It is very important to determine the form of trapped particle distribution function in the problem of plasma disturbance by a spherical absorbing body. There are two ways of solving this problem: stability analysis of the physical system or examination of initial value problem. In this work the second method has been chosen. The physical system under consideration can be described by Poisson-Vlasov equations. In the initial moment of time the absorbing sphere appears in collisionless plasma. Distribution functions for electrons and ions are assumed to be monoenergetic at the start. The aim of the study is to observe plasma dynamics at long times and to determine the steady state of the plasma. Numerical simulation is based on PIC ("particles-in-cell") method. Spherical symmetry of the problem is widely employed to simplify model and reduce calculation count. It allows to treat charged particle dynamics as a motion with one degree of freedom, while the problem as a whole remains three-dimensional. This gives an opportunity to use moderate computational resources. A massively parallel code using GPGPU and OpenCL technologies has been developed, as well as auxiliary utilities for testing, result processing and representation. As a result, spatial and temporal plasma characteristics near absorbing sphere have been obtained. Formation of trapped ion bunch in the vicinity of the sphere has been observed on the phase plane while approaching equilibrium state.

  8. Influence of injected silver content on synthesis of silver coated nickel particles by DC thermal plasma

    Science.gov (United States)

    Park, Si Taek; Kim, Tae-Hee; Park, Dong-Wha

    2016-06-01

    Silver nanoparticle-coated spherical nickel particles were prepared from a mixture of micro-sized silver and nickel as raw materials by DC thermal plasma treatment. The mixture of micro-sized silver and nickel powders was injected into the high-temperature region of an argon thermal plasma jet. Although the silver, with its very high thermal conductivity and relatively low boiling point, was thoroughly evaporated by this process, nickel was not evaporated perfectly because of its comparatively low thermal conductivity and high boiling point. The rough nickel powder was spheroidized as it melted. Finally, silver evaporated by the thermal plasma quickly condensed into nanoparticles on the surfaces of the micro-sized spherical nickel particles, aided by the sharp temperature gradient of the thermal plasma jet. With varying the ratios of silver to nickel feedstock from 1:10 to 5:1, the products synthesized in each condition were examined by XRD, XPS, FE-SEM, and FE-TEM. More silver nanoparticles were attached on the nickel by increasing the injected feedstock to 9.8 at% silver. Meanwhile, a decrease of silver in the products was observed when larger amounts of silver were introduced to the thermal plasma jet. The exposed silver components decreased with greater proportions of silver feedstock because of the metal's dendritic structure and the formation of silver-coated silver particles.

  9. Design of a high particle flux hydrogen helicon plasma source for used in plasma materials interaction studies

    Energy Technology Data Exchange (ETDEWEB)

    Goulding, Richard Howell [ORNL; Chen, Guangye [ORNL; Meitner, Steven J [ORNL; Baity Jr, F Wallace [ORNL; Caughman, John B [ORNL; Owen, Larry W [ORNL

    2009-01-01

    Existing linear plasma materials interaction (PMI) facilities all use plasma sources with internal electrodes. An rf-based helicon source is of interest because high plasma densities can be generated with no internal electrodes, allowing true steady state operation with minimal impurity generation. Work has begun at Oak Ridge National Laboratory (ORNL) to develop a large (15 cm) diameter helicon source producing hydrogen plasmas with parameters suitable for use in a linear PMI device: n(e) >= 10(19)m(-3), T(e) = 4-10 eV, particle flux Gamma(p) > 10(23) m(-3) s(-1), and magnetic field strength |B| up to I T in the source region. The device, whose design is based on a previous hydrogen helicon source operated at ORNL[1], will operate at rf frequencies in the range 10 - 26 MHz, and power levels up to similar to 100 kW. Limitations in cooling will prevent operation for pulses longer than several seconds, but a major goal will be the measurement of power deposition on device structures so that a later steady state version can be designed. The device design, the diagnostics to be used, and results of rf modeling of the device will be discussed. These include calculations of plasma loading, resulting currents and voltages in antenna structures and the matching network, power deposition profiles, and the effect of high |B| operation on power absorption.

  10. A Multi Level Multi Domain Method for Particle In Cell Plasma Simulations

    CERN Document Server

    Innocenti, M E; Markidis, S; Beck, A; Vapirev, A

    2012-01-01

    A novel adaptive technique for electromagnetic Particle In Cell (PIC) plasma simulations is presented here. Two main issues are identified in designing adaptive techniques for PIC simulation: first, the choice of the size of the particle shape function in progressively refined grids, with the need to avoid the exertion of self-forces on particles, and, second, the necessity to comply with the strict stability constraints of the explicit PIC algorithm. The adaptive implementation presented responds to these demands with the introduction of a Multi Level Multi Domain (MLMD) system (where a cloud of self-similar domains is fully simulated with both fields and particles) and the use of an Implicit Moment PIC method as baseline algorithm for the adaptive evolution. Information is exchanged between the levels with the projection of the field information from the refined to the coarser levels and the interpolation of the boundary conditions for the refined levels from the coarser level fields. Particles are bound to...

  11. Power law relation between particle concentrations and their sizes in the blood plasma

    Science.gov (United States)

    Kirichenko, M. N.; Chaikov, L. L.; Zaritskii, A. R.

    2016-08-01

    This work is devoted to the investigation of sizes and concentrations of particles in blood plasma by dynamic light scattering (DLS). Blood plasma contains many different proteins and their aggregates, microparticles and vesicles. Their sizes, concentrations and shapes can give information about donor's health. Our DLS study of blood plasma reveals unexpected dependence: with increasing of the particle sizes r (from 1 nm up to 1 μm), their concentrations decrease as r-4 (almost by 12 orders). We found also that such dependence was repeated for model solution of fibrinogen and thrombin with power coefficient is -3,6. We believe that this relation is a fundamental law of nature that shows interaction of proteins (and other substances) in biological liquids.

  12. Measurement of the Internal Magnetic Field of Plasmas using an Alpha Particle Source

    Energy Technology Data Exchange (ETDEWEB)

    S.J. Zweben; D.S. Darrow; P.W. Ross; J.L. Lowrance; G. Renda

    2004-05-13

    The internal magnetic fields of plasmas can be measured under certain conditions from the integrated v x B deflection of MeV alpha particles emitted by a small radioactive source. This alpha source and large-area alpha particle detector would be located inside the vacuum vessel but outside the plasma. Alphas with a typical energy of 5.5 MeV (241Am) can reach the center of almost all laboratory plasmas and magnetic fusion devices, so this method can potentially determine the q(r) profile of tokamaks or STs. Orbit calculations, background evaluations, and conceptual designs for such a vxB (or ''AVB'') detector are described.

  13. Laser-plasma interactions with a Fourier-Bessel Particle-in-Cell method

    CERN Document Server

    Andriyash, Igor A; Lifschitz, Agustin

    2016-01-01

    A new spectral particle-in-cell (PIC) method for plasma modeling is presented and discussed. In the proposed scheme, the Fourier-Bessel transform is used to translate the Maxwell equations to the quasi-cylindrical spectral domain. In this domain, the equations are solved analytically in time, and the spatial derivatives are approximated with high accuracy. In contrast to the finite-difference time domain (FDTD) methods that are commonly used in PIC, the developed method does not produce numerical dispersion, and does not involve grid staggering for the electric and magnetic fields. These features are especially valuable in modeling the wakefield acceleration of particles in plasmas. The proposed algorithm is implemented in the code PLARES-PIC, and the test simulations of laser plasma interactions are compared to the ones done with the quasi-cylindrical FDTD PIC code CALDER-CIRC.

  14. ELM simulation experiments on Pilot-PSI using simultaneous high flux plasma and transient heat/particle source

    NARCIS (Netherlands)

    De Temmerman, G.; Zielinski, J. J.; van Diepen, S.; Marot, L.; Price, M.

    2011-01-01

    A new experimental setup has been developed for edge localized mode (ELM) simulation experiments with relevant steady-state plasma conditions and transient heat/particle source. The setup is based on the Pilot-PSI linear plasma device and allows the superimposition of a transient heat/particle pulse

  15. Effects of oral administration of titanium dioxide fine-sized particles on plasma glucose in mice.

    Science.gov (United States)

    Gu, Ning; Hu, Hailong; Guo, Qian; Jin, Sanli; Wang, Changlin; Oh, Yuri; Feng, Yujie; Wu, Qiong

    2015-12-01

    Titanium dioxide (TiO2) is an authorized additive used as a food colorant, is composed of nano-sized particles (NP) and fine-sized particles (FP). Previous study reported that oral administration of TiO2 NPs triggers an increase in plasma glucose of mice. However, no previous studies have focused on toxic effects of TiO2 FPs on plasma glucose homeostasis following oral administration. In the current study, mice were orally administered TiO2 FPs greater than 100 nm in size (64 mg/kg body weight per day), and effects on plasma glucose levels examined. Our results showed that titanium levels was not changed in mouse blood, livers and pancreases after mice were orally administered TiO2 FPs. Biochemical analyzes showed that plasma glucose and ROS levels were not affected by TiO2 FPs. Histopathological results showed that TiO2 FPs did not induce pathology changes in organs, especially plasma glucose homeostasis regulation organs, such as pancreas and liver. Western blotting showed that oral administration of TiO2 FPs did not induce insulin resistance (IR) in mouse liver. These results showed that, TiO2 FPs cannot be absorbed via oral administration and affect plasma glucose levels in mice.

  16. Dynamics of magnetically trapped particles foundations of the physics of radiation belts and space plasmas

    CERN Document Server

    Roederer, Juan G

    2014-01-01

    This book is a new edition of Roederer’s classic Dynamics of Geomagnetically Trapped Radiation, updated and considerably expanded. The main objective is to describe the dynamic properties of magnetically trapped particles in planetary radiation belts and plasmas and explain the physical processes involved from the theoretical point of view. The approach is to examine in detail the orbital and adiabatic motion of individual particles in typical configurations of magnetic and electric fields in the magnetosphere and, from there, derive basic features of the particles’ collective “macroscopic” behavior in general planetary environments. Emphasis is not on the “what” but on the “why” of particle phenomena in near-earth space, providing a solid and clear understanding of the principal basic physical mechanisms and dynamic processes involved. The book will also serve as an introduction to general space plasma physics, with abundant basic examples to illustrate and explain the physical origin of diff...

  17. Cylindrical dielectric barrier discharge plasma catalytic effect on chemical methods of silver nano-particle production

    Science.gov (United States)

    Bahrami, Zahra; Khani, Mohammad Reza; Shokri, Babak

    2016-11-01

    In this study, cylindrical dielectric barrier discharge plasma was used to study the catalytic effect on chemical methods of silver nano-particles for the first time. In this method, the processing time is short and the temperature of reaction is low. Also, the reactor is very simple, inexpensive, and accessible. In this work, pure AgNO3 as the precursor agent and poly vinyl pyrrolidone as the macromolecular surfactant were dissolved in ethanol as the solvent. UV-Vis and XRD were used to identify the colloidal and powder nano-particles, respectively. Optical emission spectroscopy was also used to identify the active species in plasma. Effects of gas flow rate, voltage, volume of solution, and processing time were also studied. Moreover, TEM and SEM images presented the mean diameter of nano-particle size around 10 to 20 nm. The results have been very promising.

  18. Simulations of Damping of Trapped Particle Asymmetry Modes in Non-Neutral Plasma Columns

    Science.gov (United States)

    Mason, Grant W.; Spencer, Ross L.

    2002-11-01

    Kabantsev et al.(A. A. Kabantsev, C. F. Driscoll, T. J. Hilsabeck, T. M. O'Neil and J. H.Yu, in Non-Neutral Plasma Physics IV), AIP Conference Proceedings 606, 2001, pp. 277-286 have reported experimental observations and theory for trapped particle asymmetry modes on cylindrical electron columns. In particular, the m=1; k_z=odd mode exhibits strong damping from an unknown mechanism that is conjectured by Kabantsev et al. to be either diffusive mixing of trapped and untrapped populations of particles or spatial Landau damping. We have observed similar damping within a 3-dimensional particle-in-cell simulation. The simulation model does not include diffusive mixing. Spatial Landau damping is also ruled out because the mode frequencies in the simulation intersect the rotation frequency curve outside the plasma. We describe efforts to isolate the mechanism of the damping.

  19. Self-Consistent Fokker-Planck Treatment Of Particle Distributions in Astrophysical Plasmas

    CERN Document Server

    Nayakshin, S; Nayakshin, Sergei; Melia, Fulvio

    1997-01-01

    High-energy, multi-component plasmas in which pair creation and annihilation, lepton-lepton scattering, lepton-proton scattering, and Comptonization all contribute to establishing the particle and photon distributions, are present in a broad range of compact astrophysical objects. Earlier work has included much of the microphysics needed to account for electron-photon and electron-proton interactions, but little has been done to handle the redistribution of the particles as a result of their Coulomb interaction with themselves in an arbitrary case. Our goal here is to use a Fokker-Planck approach in order to develop a fully self-consistent theory for the interaction of arbitrarily distributed particles and radiation to arrive at an accurate representation of the high-energy plasma in these sources. We conduct several tests representative of two dominant segments of parameter space and discuss physical implications of the non-Maxwellian distribution function. Approximate analytical forms for the electron distr...

  20. Absorption of electromagnetic waves by the dust particles in a plasma

    Institute of Scientific and Technical Information of China (English)

    LI; Fang; LI; Lianlin; SUI; Qiang

    2004-01-01

    Absorption of electromagnetic waves by the dust particles in a plasma has been studied based on a Mie-Debye scattering mode. The longitudinal field of the Debye scattering has been derived and the wave energy loss from it has been calculated. It is shown that the lower the temperature of the plasma is and the higher the density of the plasma is, the larger the absorption cross section will be due to the longitudinal scattering.For the low frequency waves the electromagnetic waves scattered in a dusty plasma are mainly in the form of Debye scattering. In this case the energy loss due to the longitudinal scattering will affect the wave propagation seriously.

  1. Propagation of waves in a multicomponent plasma having charged dust particles

    Indian Academy of Sciences (India)

    Sukanya Burman; A Roy Chowdhury; S N Paul

    2001-06-01

    Propagation of both low and high frequency waves in a plasma consisting of electrons, ions, positrons and charged dust particles have been theoretically studied. The characteristics of dust acoustic wave propagating through the plasma has been analysed and the dispersion relation deduced is a generalization of that obtained by previous authors. It is found that nonlinear localization of high frequency electromagnetic field in such a plasma generates magnetic field. This magnetic field is seen to depend on the temperatures of electrons and positrons and also on their equilibrium density ratio. It is suggested that the present model would be applicable to find the magnetic field generation in space plasma.

  2. Measuring Collisionless Damping in Heliospheric Plasmas using Field-Particle Correlations

    Science.gov (United States)

    Klein, K. G.; Howes, G. G.

    2016-08-01

    An innovative field-particle correlation technique is proposed that uses single-point measurements of the electromagnetic fields and particle velocity distribution functions to investigate the net transfer of energy from fields to particles associated with the collisionless damping of turbulent fluctuations in weakly collisional plasmas, such as the solar wind. In addition to providing a direct estimate of the local rate of energy transfer between fields and particles, it provides vital new information about the distribution of that energy transfer in velocity space. This velocity-space signature can potentially be used to identify the dominant collisionless mechanism responsible for the damping of turbulent fluctuations in the solar wind. The application of this novel field-particle correlation technique is illustrated using the simplified case of the Landau damping of Langmuir waves in an electrostatic 1D-1V Vlasov-Poisson plasma, showing that the procedure both estimates the local rate of energy transfer from the electrostatic field to the electrons and indicates the resonant nature of this interaction. Modifications of the technique to enable single-point spacecraft measurements of fields and particles to diagnose the collisionless damping of turbulent fluctuations in the solar wind are discussed, yielding a method with the potential to transform our ability to maximize the scientific return from current and upcoming spacecraft missions, such as the Magnetospheric Multiscale (MMS) and Solar Probe Plus missions.

  3. Wavelet-based density estimation for noise reduction in plasma simulations using particles

    Science.gov (United States)

    van yen, Romain Nguyen; del-Castillo-Negrete, Diego; Schneider, Kai; Farge, Marie; Chen, Guangye

    2010-04-01

    For given computational resources, the accuracy of plasma simulations using particles is mainly limited by the noise due to limited statistical sampling in the reconstruction of the particle distribution function. A method based on wavelet analysis is proposed and tested to reduce this noise. The method, known as wavelet-based density estimation (WBDE), was previously introduced in the statistical literature to estimate probability densities given a finite number of independent measurements. Its novel application to plasma simulations can be viewed as a natural extension of the finite size particles (FSP) approach, with the advantage of estimating more accurately distribution functions that have localized sharp features. The proposed method preserves the moments of the particle distribution function to a good level of accuracy, has no constraints on the dimensionality of the system, does not require an a priori selection of a global smoothing scale, and its able to adapt locally to the smoothness of the density based on the given discrete particle data. Moreover, the computational cost of the denoising stage is of the same order as one time step of a FSP simulation. The method is compared with a recently proposed proper orthogonal decomposition based method, and it is tested with three particle data sets involving different levels of collisionality and interaction with external and self-consistent fields.

  4. Particle Densities of the Atmospheric-Pressure Argon Plasmas Generated by the Pulsed Dielectric Barrier Discharges

    Science.gov (United States)

    Pan, Jie; Li, Li; Wang, Yunuan; Xiu, Xianwu; Wang, Chao; Song, Yuzhi

    2016-11-01

    Atmospheric-pressure argon plasmas have received increasing attention due to their high potential in many industrial and biomedical applications. In this paper, a 1-D fluid model is used for studying the particle density characteristics of the argon plasmas generated by the pulsed dielectric barrier discharges. The temporal evolutions of the axial particle density distributions are illustrated, and the influences of changing the main discharge conditions on the averaged particle densities are researched by independently varying the various discharge conditions. The calculation results show that the electron density and the ion density reach two peaks near the momentary cathodes during the rising and the falling edges of the pulsed voltage. Compared with the charged particle densities, the densities of the resonance state atom Arr and the metastable state atom Arm have more uniform axial distributions, reach higher maximums and decay more slowly. During the platform of the pulsed voltage and the time interval between the pulses, the densities of the excited state atom Ar* are far lower than those of the Arr or the Arm. The averaged particle densities of the different considered particles increase with the increases of the amplitude and the frequency of the pulsed voltage. Narrowing the discharge gap and increasing the relative dielectric constant of the dielectric also contribute to the increase of the averaged particle densities. The effects of reducing the discharge gap distance on the neutral particle densities are more significant than the influences on the charged particle densities. supported by Natural Science Foundation of Shandong Province, China (No. ZR2015AQ008), and Project of Shandong Province Higher Educational Science and Technology Program of China (No. J15LJ04)

  5. Plasma Processing of SRF Cavities for the next Generation Of Particle Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Vuskovic, Leposava

    2015-11-23

    The cost-effective production of high frequency accelerating fields are the foundation for the next generation of particle accelerators. The Ar/Cl2 plasma etching technology holds the promise to yield a major reduction in cavity preparation costs. Plasma-based dry niobium surface treatment provides an excellent opportunity to remove bulk niobium, eliminate surface imperfections, increase cavity quality factor, and bring accelerating fields to higher levels. At the same time, the developed technology will be more environmentally friendly than the hydrogen fluoride-based wet etching technology. Plasma etching of inner surfaces of standard multi-cell SRF cavities is the main goal of this research in order to eliminate contaminants, including niobium oxides, in the penetration depth region. Successful plasma processing of multi-cell cavities will establish this method as a viable technique in the quest for more efficient components of next generation particle accelerators. In this project the single-cell pill box cavity plasma etching system is developed and etching conditions are determined. An actual single cell SRF cavity (1497 MHz) is plasma etched based on the pill box cavity results. The first RF test of this plasma etched cavity at cryogenic temperature is obtained. The system can also be used for other surface modifications, including tailoring niobium surface properties, surface passivation or nitriding for better performance of SRF cavities. The results of this plasma processing technology may be applied to most of the current SRF cavity fabrication projects. In the course of this project it has been demonstrated that a capacitively coupled radio-frequency discharge can be successfully used for etching curved niobium surfaces, in particular the inner walls of SRF cavities. The results could also be applicable to the inner or concave surfaces of any 3D structure other than an SRF cavity.

  6. Core/shell silicon/polyaniline particles via in-flight plasma-induced polymerization

    Science.gov (United States)

    Yasar-Inceoglu, Ozgul; Zhong, Lanlan; Mangolini, Lorenzo

    2015-08-01

    Although silicon nanoparticles have potential applications in many relevant fields, there is often the need for post-processing steps to tune the property of the nanomaterial and to optimize it for targeted applications. In particular surface modification is generally necessary to both tune dispersibility of the particles in desired solvents to achieve optimal coating conditions, and to interface the particles with other materials to realize functional heterostructures. In this contribution we discuss the realization of core/shell silicon/polymer nanoparticles realized using a plasma-initiated in-flight polymerization process. Silicon particles are produced in a non-thermal plasma reactor using silane as a precursor. After synthesis they are aerodynamically injected into a second plasma reactor into which aniline vapor is introduced. The second plasma initiates the polymerization reactor leading to the formation of a 3-4 nm thick polymer shell surrounding the silicon core. The role of processing conditions on the properties of the polymeric shell is discussed. Preliminary results on the testing of this material as an anode for lithium ion batteries are presented.

  7. Heat Transfer to a Particle Exposed to a Rarefied Plasma with a Great Temperature Gradient

    Institute of Scientific and Technical Information of China (English)

    XiChen; XinTao

    1993-01-01

    A kinetic-theory analysis is presented concerning the heat transfer from a rarefiled plasma to a spherical particle for the extreme case of free-molecule regime and thin phasma sheath.A great temperature gradient is assumed to exist in the plasma,and thus a non-Maxwellian velocity distribution function is employed for each of the gas species.Analytical results show that the existence of a temperature in employed for each of the gas species,Analytical results show that the existence of a temperature gradient in the plasma causes a nonuniform distribution of the local heat flux density on the sphere surface,while the total heat flux to the whole particle is independent of the temperature gradient.The nonuniformity of the local heat flux distributioln is small even for the case with a temperature gradient as great as 106 K/m,but it may significantly enhance the thermophoretic force on an evaporating particle,Heat transfer is mainly caused by atome at low gas temperatures with negligible ionization degree,while it can be attributed to ions and electrons at high plasma temperatures.

  8. Anomalous kinetic energy of a system of dust particles in a gas discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Norman, G. E., E-mail: norman@ihed.ras.ru; Stegailov, V. V., E-mail: stegailov@gmail.com; Timofeev, A. V., E-mail: timofeevalvl@gmail.com [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2011-11-15

    The system of equations of motion of dust particles in a near-electrode layer of a gas discharge has been formulated taking into account fluctuations of the charge of a dust particle and the features of the nearelectrode layer of the discharge. The molecular dynamics simulation of the system of dust particles has been carried out. Performing a theoretical analysis of the simulation results, a mechanism of increasing the average kinetic energy of dust particles in the gas discharge plasma has been proposed. According to this mechanism, the heating of the vertical oscillations of dust particles is initiated by induced oscillations generated by fluctuations of the charge of dust particles, and the energy transfer from vertical to horizontal oscillations can be based on the parametric resonance phenomenon. The combination of the parametric and induced resonances makes it possible to explain an anomalously high kinetic energy of dust particles. The estimate of the frequency, amplitude, and kinetic energy of dust particles are close to the respective experimental values.

  9. The energy partitioning of non-thermal particles in a plasma: or the Coulomb logarithm revisited

    CERN Document Server

    Singleton, Robert L

    2008-01-01

    The charged particle stopping power in a highly ionized and weakly to moderately coupled plasma has been calculated to leading and next-to-leading order by Brown, Preston, and Singleton (BPS). After reviewing the main ideas behind this calculation, we use a Fokker-Planck equation derived by BPS to compute the electron-ion energy partitioning of a charged particle traversing a plasma. The motivation for this application is ignition for inertial confinement fusion -- more energy delivered to the ions means a better chance of ignition, and conversely. It is therefore important to calculate the fractional energy loss to electrons and ions as accurately as possible, as this could have implications for the Laser Megajoule (LMJ) facility in France and the National Ignition Facility (NIF) in the United States. The traditional method by which one calculates the electron-ion energy splitting of a charged particle traversing a plasma involves integrating the stopping power dE/dx. However, as the charged particle slows d...

  10. Collisionless shocks and particle acceleration in laser-driven laboratory plasmas

    Science.gov (United States)

    Fiuza, Frederico

    2012-10-01

    Collisionless shocks are pervasive in space and astrophysical plasmas, from the Earth's bow shock to Gamma Ray Bursters; however, the microphysics underlying shock formation and particle acceleration in these distant sites is not yet fully understood. Mimicking these extreme conditions in laboratory is a grand challenge that would allow for a better understanding of the physical processes involved. Using ab initio multi-dimensional particle-in-cell simulations, shock formation and particle acceleration are investigated for realistic laboratory conditions associated with the interaction of intense lasers with high-energy-density plasmas. Weibel-instability-mediated shocks are shown to be driven by the interaction of an ultraintense laser with overcritical plasmas. In this piston regime, the laser generates a relativistic flow that is Weibel unstable. The strong Weibel magnetic fields deflect the incoming flow, compressing it, and forming a shock. The resulting shock structure is consistent with previous simulations of relativistic astrophysical shocks, demonstrating for the first time the possibility of recreating these structures in laboratory. As the laser intensity is decreased and near-critical density plasmas are used, electron heating dominates over radiation pressure and electrostatic shocks can be formed. The electric field associated with the shock front can reflect ions from the background accelerating them to high energies. It is shown that high quality 200 MeV proton beams, required for tumor therapy, can be generated by using an exponentially decaying plasma profile to control competing accelerating fields. These results pave the way for the experimental exploration of space and astrophysical relevant shocks and particle acceleration with current laser systems.

  11. A model for particle confinement in a toroidal plasma subject to strong radial electric fields

    Science.gov (United States)

    Roth, J. R.

    1977-01-01

    The approach adopted in the NASA Lewis Bumpy Torus experiment is to confine and heat a toroidal plasma by the simultaneous application of strong dc magnetic fields and electric fields. Strong radial electric fields (about 1 kV/cm) are imposed by biasing the plasma with up to 12 negative electrode rings which surround its minor circumference. The plasma containment is consistent with a balance of two processes: a radial infusion of ions in those sectors not containing electrode rings, resulting from the radially inward electric fields; and ion losses to the electrode rings, each of which acts as a sink and draws ions out the plasma in the manner of a Langmuir probe in the ion saturation regime. The highest density on axis which has been observed so far in this steady-state plasma is 6.2 trillion particles per cu cm, for which the particle containment time is 2.5 msec. The deuterium ion kinetic temperature for these conditions was in the range of 360 to 520 eV.

  12. Simulation of cold atmospheric plasma component composition and particle densities in air

    Science.gov (United States)

    Kirsanov, Gennady; Chirtsov, Alexander; Kudryavtsev, Anatoliy

    2015-11-01

    Recently discharges in air at atmospheric pressure were the subject of numerous studies. Of particular interest are the cold streams of air plasma, which contains large amounts of chemically active species. It is their action can be decisive in the interaction with living tissues. Therefore, in addition to its physical properties, it is important to know the component composition and particle densities. The goal was to develop a numerical model of atmospheric pressure glow microdischarge in air with the definition of the component composition of plasma. To achieve this goal the task was divided into two sub-tasks, in the first simulated microdischarge atmospheric pressure in air using a simplified set of plasma chemical reactions in order to obtain the basic characteristics of the discharge, which are the initial approximations in the problem of the calculation of the densities with detailed plasma chemistry, including 53 spices and over 600 chemical reactions. As a result of the model was created, which can be adapted for calculating the component composition of plasma of various sources. Calculate the density of particles in the glow microdischarges and dynamics of their change in time.

  13. Magnetic stochasticity in magnetically confined fusion plasmas chaos of field lines and charged particle dynamics

    CERN Document Server

    Abdullaev, Sadrilla

    2014-01-01

    This is the first book to systematically consider the modern aspects of chaotic dynamics of magnetic field lines and charged particles in magnetically confined fusion plasmas.  The analytical models describing the generic features of equilibrium magnetic fields and  magnetic perturbations in modern fusion devices are presented. It describes mathematical and physical aspects of onset of chaos, generic properties of the structure of stochastic magnetic fields, transport of charged particles in tokamaks induced by magnetic perturbations, new aspects of particle turbulent transport, etc. The presentation is based on the classical and new unique mathematical tools of Hamiltonian dynamics, like the action--angle formalism, classical perturbation theory, canonical transformations of variables, symplectic mappings, the Poincaré-Melnikov integrals. They are extensively used for analytical studies as well as for numerical simulations of magnetic field lines, particle dynamics, their spatial structures and  statisti...

  14. Nonlinear dynamics of phase space zonal structures and energetic particle physics in fusion plasmas

    CERN Document Server

    Zonca, Fulvio; Briguglio, Sergio; Fogaccia, Giuliana; Vlad, Gregorio; Wang, Xin

    2014-01-01

    A general theoretical framework for investigating nonlinear dynamics of phase space zonal structures is presented in this work. It is then, more specifically, applied to the limit where the nonlinear evolution time scale is smaller or comparable to the wave-particle trapping period. In this limit, both theoretical and numerical simulation studies show that non-adiabatic frequency chirping and phase locking could lead to secular resonant particle transport on meso- or macro-scales. The interplay between mode structures and resonant particles then provides the crucial ingredient to properly understand and analyze the nonlinear dynamics of Alfv\\'en wave instabilities excited by non-perturbative energetic particles in burning fusion plasmas. Analogies with autoresonance in nonlinear dynamics and with superradiance in free electron lasers are also briefly discussed.

  15. Wake-Mediated Propulsion of an Upstream Particle in Two-Dimensional Plasma Crystals

    Science.gov (United States)

    Laut, I.; Räth, C.; Zhdanov, S. K.; Nosenko, V.; Morfill, G. E.; Thomas, H. M.

    2017-02-01

    The wake-mediated propulsion of an "extra" particle in a channel of two neighboring rows of a two-dimensional plasma crystal, observed experimentally by Du et al. [Phys. Rev. E 89, 021101(R) (2014), 10.1103/PhysRevE.89.021101], is explained in simulations and theory. We use the simple model of a pointlike ion wake charge to reproduce this intriguing effect in simulations, allowing for a detailed investigation and a deeper understanding of the underlying dynamics. We show that the nonreciprocity of the particle interaction, owing to the wake charges, is responsible for a broken symmetry of the channel that enables a persistent self-propelled motion of the extra particle. We find good agreement of the terminal extra-particle velocity with our theoretical considerations and with experiments.

  16. Particle acceleration and radiation friction effects in the filamentation instability of pair plasmas

    CERN Document Server

    D'Angelo, M; Sgattoni, A; Pegoraro, F; Macchi, A

    2015-01-01

    The evolution of the filamentation instability produced by two counter-streaming pair plasmas is studied with particle-in-cell (PIC) simulations in both one (1D) and two (2D) spatial dimensions. Radiation friction effects on particles are taken into account. After an exponential growth of both the magnetic field and the current density, a nonlinear quasi-stationary phase sets up characterized by filaments of opposite currents. During the nonlinear stage, a strong broadening of the particle energy spectrum occurs accompanied by the formation of a peak at twice their initial energy. A simple theory of the peak formation is presented. The presence of radiative losses does not change the dynamics of the instability but affects the structure of the particle spectra.

  17. Inductively Coupled Plasma: Fundamental Particle Investigations with Laser Ablation and Applications in Magnetic Sector Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Saetveit, Nathan Joe [Iowa State Univ., Ames, IA (United States)

    2008-01-01

    Particle size effects and elemental fractionation in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are investigated with nanosecond and femtosecond laser ablation, differential mobility analysis, and magnetic sector ICP-MS. Laser pulse width was found to have a significant influence on the LA particle size distribution and the elemental composition of the aerosol and thus fractionation. Emission from individual particles from solution nebulization, glass, and a pressed powder pellet are observed with high speed digital photography. The presence of intact particles in an ICP is shown to be a likely source of fractionation. A technique for the online detection of stimulated elemental release from neural tissue using magnetic sector ICP-MS is described. Detection limits of 1 μg L-1 or better were found for P, Mn, Fe, Cu, and Zn in a 60 μL injection in a physiological saline matrix.

  18. On the coupling of fields and particles in accelerator and plasma physics

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2016-10-15

    In accelerator and plasma physics it is generally accepted that there is no need to solve the dynamical equations for particles motion in manifestly covariant form, that is by using the coordinate-independent proper time to parameterize particle world-lines in space-time. In other words, in order to describe the dynamical processes in the laboratory frame there is no need to use the laws of relativistic kinematics. It is sufficient to take into account the relativistic dependence of the particles momentum on the velocity in the second Newton's law. Therefore, the coupling of fields and particles is based, on the one hand, on the use of result from particle dynamics treated according to Newton's laws in terms of the relativistic three-momentum and, on the other hand, on the use of Maxwell's equations in standard form. In previous papers we argued that this is a misconception. The purpose of this paper is to describe in detail how to calculate the coupling between fields and particles in a correct way and how to develop a new algorithm for a particle tracking code in agreement with the use of Maxwell's equations in their standard form. Advanced textbooks on classical electrodynamics correctly tell us that Maxwell's equations in standard form in the laboratory frame and charged particles are coupled by introducing particles trajectories as projections of particles world-lines onto coordinates of the laboratory frame and by subsequently using the laboratory time to parameterize the trajectory curves. For the first time we showed a difference between conventional and covariant particle tracking results in the laboratory frame. This essential point has never received attention in the physical community. Only the solution of the dynamical equations in covariant form gives the correct coupling between field equations in standard form and particles trajectories in the laboratory frame. We conclude that previous theoretical and simulation results in

  19. Exploring the role of turbulent acceleration and heating in fractal current sheet of solar flares­ from hybrid particle in cell and lattice Boltzmann virtual test

    Science.gov (United States)

    Zhu, B.; Lin, J.; Yuan, X.; Li, Y.; Shen, C.

    2016-12-01

    The role of turbulent acceleration and heating in the fractal magnetic reconnection of solar flares is still not clear, especially at the X-point in the diffusion region. At virtual test aspect, it is hardly to quantitatively analyze the vortex generation, turbulence evolution, particle acceleration and heating in the magnetic islands coalesce in fractal manner, formatting into largest plasmid and ejection process in diffusion region through classical magnetohydrodynamics numerical method. With the development of physical particle numerical method (particle in cell method [PIC], Lattice Boltzmann method [LBM]) and high performance computing technology in recently two decades. Kinetic simulation has developed into an effectively manner to exploring the role of magnetic field and electric field turbulence in charged particles acceleration and heating process, since all the physical aspects relating to turbulent reconnection are taken into account. In this paper, the LBM based lattice DxQy grid and extended distribution are added into charged-particles-to-grid-interpolation of PIC based finite difference time domain scheme and Yee Grid, the hybrid PIC-LBM simulation tool is developed to investigating turbulence acceleration on TIANHE-2. The actual solar coronal condition (L≈105Km,B≈50-500G,T≈5×106K, n≈108-109, mi/me≈500-1836) is applied to study the turbulent acceleration and heating in solar flare fractal current sheet. At stage I, magnetic islands shrink due to magnetic tension forces, the process of island shrinking halts when the kinetic energy of the accelerated particles is sufficient to halt the further collapse due to magnetic tension forces, the particle energy gain is naturally a large fraction of the released magnetic energy. At stage II and III, the particles from the energized group come in to the center of the diffusion region and stay longer in the area. In contract, the particles from non energized group only skim the outer part of the

  20. Analytical model of particle and heat flux collection by dust immersed in dense magnetized plasmas

    Science.gov (United States)

    Vignitchouk, L.; Ratynskaia, S.; Tolias, P.

    2017-10-01

    A comprehensive analytical description is presented for the particle and heat fluxes collected by dust in dense magnetized plasmas. Compared to the widely used orbital motion limited theory, the suppression of cross-field transport leads to a strong reduction of the electron fluxes, while ion collection is inhibited by thin-sheath effects and the formation of a potential overshoot along the field lines. As a result, the incoming heat flux loses its sensitivity to the floating potential, thereby diminishing the importance of electron emission processes in dust survivability. Numerical simulations implementing the new model for ITER-like detached divertor plasmas predict a drastic enhancement of the dust lifetime.

  1. Influence of superthermal plasma particles on the Jeans instability in self-gravitating dusty plasmas with dust charge variations

    Energy Technology Data Exchange (ETDEWEB)

    Hakimi Pajouh, H., E-mail: hakimi@alzahra.ac.ir; Afshari, N.

    2016-11-25

    Highlights: • The current of superthermal electrons and ions on the dust surface is calculated. • Increase in the superthermal particles number increases growth rate of instability. • Increase in the superthermal particles number decreases DA waves frequency. • By decreasing κ, the ratio of electric to self-gravitational force is decreased. • Dust charge variations decreases the ratio of electric to self-gravitational force. - Abstract: A theoretical analysis of the dust acoustic waves in the self-gravitating dusty plasmas is presented within the consideration of the superthermal electrons, ions and dust charge variations. For this purpose, the current of electrons and ions to the dust surface is calculated, and then the dispersion relation for the dust acoustic waves is obtained. It is shown that by increasing the number of superthermal particles, the growth rate of the instability increases, the dust acoustic waves frequency decreases, and the instability region is extended to the smaller wavelengths. Moreover, it is found that the ratio of the electric force to the self-gravitational force is decreased in the presence of the superthermal particles, and dust charge variations.

  2. Particle Acceleration in Collapsing Magnetic Traps with a Braking Plasma Jet

    CERN Document Server

    Borissov, Alexei; Threlfall, James

    2016-01-01

    Collapsing magnetic traps (CMTs) are one proposed mechanism for generating non-thermal particle populations in solar flares. CMTs occur if an initially stretched magnetic field structure relaxes rapidly into a lower-energy configuration, which is believed to happen as a by-product of magnetic reconnection. A similar mechanism for energising particles has also been found to operate in the Earth's magnetotail. One particular feature proposed to be of importance for particle acceleration in the magnetotail is that of a braking plasma jet, i.e. a localised region of strong flow encountering stronger magnetic field which causes the jet to slow down and stop. Such a feature has not been included in previously proposed analytical models of CMTs for solar flares. In this work we incorporate a braking plasma jet into a well studied CMT model for the first time. We present results of test particle calculations in this new CMT model. We observe and characterise new types of particle behaviour caused by the magnetic stru...

  3. The Interparticle Interaction Between a Vertically Aligned Dust Particle Pair in a Complex Plasma

    Science.gov (United States)

    Qiao, Ke; Ding, Zhiyue; Kong, Jie; Matthews, Lorin; Hyde, Truell

    2016-10-01

    The interaction between dust particles is a fundamental topic in complex plasma. In experiments on earth, the interparticle interaction in the horizontal direction (i.e., perpendicular to the gravitational force) is generally recognized to be a Yukawa potential. However, the interaction in the vertical direction is much more complicated, primarily due to the ion flow in the plasma sheath. In this research, we introduce a non-intrusive method to study the interaction between a vertically aligned dust particle pair confined in a glass box placed on the lower powered electrode within a GEC reference cell. This system is investigated for varying rf powers to obtain the trend of the interparticle interaction strength, which is contrasted with theoretical results. Using spontaneous thermal fluctuations of the neutral gas as the only driving force, we obtain the normal mode spectra of the dust pair, revealing not only the oscillation frequencies, but also the vibration amplitudes of the normal modes. The interaction strength between the upper and lower particle is obtained quantitatively from these mode spectra, showing strong nonreciprocity in both the vertical and horizontal directions. It will also be shown that the resulting horizontal attractive force of the upper particle on the lower particle can be larger than the horizontal confinement produced by the glass box alone. NSF / DOE funding is gratefully acknowledged - PHY1414523 & PHY1262031.

  4. Optimization Of Pulsed Current Parameters To Minimize Pitting Corrosion İn Pulsed Current Micro Plasma Arc Welded Aısı 304l Sheets Using Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Kondapalli Siva Prasad

    2013-06-01

    Full Text Available Austenitic stainless steel sheets have gathered wide acceptance in the fabrication of components, which require high temperature resistance and corrosion resistance, such as metal bellows used in expansion joints in aircraft, aerospace and petroleum industry. In case of single pass welding of thinner sections of this alloy, Pulsed Current Micro Plasma Arc Welding (PCMPAW was found beneficial due to its advantages over the conventional continuous current process. This paper highlights the development of empirical mathematical equations using multiple regression analysis, correlating various process parameters to pitting corrosion rates in PCMPAW of AISI 304L sheets in 1 Normal HCl. The experiments were conducted based on a five factor, five level central composite rotatable design matrix. A Genetic Algorithm (GA was developed to optimize the process parameters for minimizing the pitting corrosion rates.

  5. Final Report - Interaction of radiation and charged particles in miniature plasma structures

    Energy Technology Data Exchange (ETDEWEB)

    Antonsen, Thomas M. [Univ. of Maryland, College Park, MD (United States). Inst. for Electronics and Applied Physics

    2014-07-16

    The extension of our program to the development of theories and models capable of describing the interactions of intense laser pulses and charged particles in miniature plasma channels is reported. These channels, which have recently been created in the laboratory, have unique dispersion properties that make them interesting for a variety of applications including particle acceleration, high harmonic generation, and THz generation. Our program systematically explored the properties of these channels, including dispersion, losses, and coupling. A particular application that was pursued is the generation of intense pulses of THz radiation by short laser pulses propagating these channels. We also explored the nonlinear dynamics of laser pulses propagating in these channels.

  6. Morphology and Phase Compositions of Hydroxyapatite Powder Particles Plasma-sprayed into Water

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Hydroxyapatite powder particles were plasma sprayed into water, their inner structures and phase compositions were studied by using scanning electron microscope(SEM) and X-ray difiractometer. The results show that the molten HA particles have a central hollow morphology and high crystallinity. The hollow morphology was caused by sublimated P2O5 and H2O, which will have an efiect on surface morphology, cohesive and adhesive strength as well as dissolution and degradation of coating. The high crystallinity is attributed to lower cooling speed in water.

  7. Azimuthal inhomogeneity of turbulence structure and its impact on intermittent particle transport in linear magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, T., E-mail: kobayashi.tatsuya@LHD.nifs.ac.jp [National Institute for Fusion Science, Toki 509-5292 (Japan); Inagaki, S.; Sasaki, M.; Nagashima, Y.; Kasuya, N.; Fujisawa, A.; Itoh, S.-I. [Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580 (Japan); Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580 (Japan); Kosuga, Y. [Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580 (Japan); Institute for Advanced Study, Kyushu University, Fukuoka 812-8581 (Japan); Arakawa, H. [Teikyo University, 6-22 Misakimachi, Omuta 836-8505 (Japan); Yamada, T. [Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580 (Japan); Faculty of Arts and Science, Kyushu University, Nishi-ku, Fukuoka 819-0395 (Japan); Miwa, Y. [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga 816-8580 (Japan); Itoh, K. [National Institute for Fusion Science, Toki 509-5292 (Japan); Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580 (Japan)

    2015-11-15

    Fluctuation component in the turbulence regime is found to be azimuthally localized at a phase of the global coherent modes in a linear magnetized plasma PANTA. Spatial distribution of squared bicoherence is given in the azimuthal cross section as an indicator of nonlinear energy transfer function from the global coherent mode to the turbulence. Squared bicoherence is strong at a phase where the turbulence amplitude is large. As a result of the turbulence localization, time evolution of radial particle flux becomes bursty. Statistical features such as skewness and kurtosis are strongly modified by the localized turbulence component, although contribution to mean particle flux profile is small.

  8. On the Coupling of Fields and Particles in Accelerator and Plasma Physics

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2016-01-01

    In accelerator and plasma physics it is accepted that there is no need to solve the dynamical equations for particles in covariant form, i.e. by using the coordinate-independent proper time to parameterize particle world-lines in space-time: to describe dynamics in the laboratory frame, there is no need to use the laws of relativistic kinematics. It is sufficient to account for the relativistic dependence of particles momenta on the velocity in the second Newton's law. Then, the coupling of fields and particles is based on the use of result from particle dynamics treated according to Newton's laws in terms of the relativistic three-momentum and on the use of Maxwell's equations in standard form. Previously, we argued that this is a misconception. Here we describe in detail how to calculate the coupling between fields and particles in a correct way and how to develop a new algorithm for a particle tracking code in agreement with the use of Maxwell's equations in their standard form. Advanced textbooks on class...

  9. Application of adaptive mesh refinement to particle-in-cell simulations of plasmas and beams

    Energy Technology Data Exchange (ETDEWEB)

    Vay, J.-L.; Colella, P.; Kwan, J.W.; McCorquodale, P.; Serafini, D.B.; Friedman, A.; Grote, D.P.; Westenskow, G.; Adam, J.-C.; Heron, A.; Haber, I.

    2003-11-04

    Plasma simulations are often rendered challenging by the disparity of scales in time and in space which must be resolved. When these disparities are in distinctive zones of the simulation domain, a method which has proven to be effective in other areas (e.g. fluid dynamics simulations) is the mesh refinement technique. We briefly discuss the challenges posed by coupling this technique with plasma Particle-In-Cell simulations, and present examples of application in Heavy Ion Fusion and related fields which illustrate the effectiveness of the approach. We also report on the status of a collaboration under way at Lawrence Berkeley National Laboratory between the Applied Numerical Algorithms Group (ANAG) and the Heavy Ion Fusion group to upgrade ANAG's mesh refinement library Chombo to include the tools needed by Particle-In-Cell simulation codes.

  10. Improved Wear Resistance of Low Carbon Steel with Plasma Melt Injection of WC Particles

    Science.gov (United States)

    Liu, Aiguo; Guo, Mianhuan; Hu, Hailong

    2010-08-01

    Surface of a low carbon steel Q235 substrate was melted by a plasma torch, and tungsten carbide (WC) particles were injected into the melt pool. WC reinforced surface metal matrix composite (MMC) was synthesized. Dry sliding wear behavior of the surface MMC was studied and compared with the substrate. The results show that dry sliding wear resistance of low carbon steel can be greatly improved by plasma melt injection of WC particles. Hardness of the surface MMC is much higher than that of the substrate. The high hardness lowers the adhesion and abrasion of the surface MMC, and also the friction coefficient of it. The oxides formed in the sliding process also help to lower the friction coefficient. In this way, the dry sliding wear resistance of the surface MMC is greatly improved.

  11. Particle-in-cell simulations of plasma accelerators and electron-neutral collisions

    Energy Technology Data Exchange (ETDEWEB)

    Bruhwiler, David L.; Giacone, Rodolfo E.; Cary, John R.; Verboncoeur, John P.; Mardahl, Peter; Esarey, Eric; Leemans, W.P.; Shadwick, B.A.

    2001-10-01

    We present 2-D simulations of both beam-driven and laser-driven plasma wakefield accelerators, using the object-oriented particle-in-cell code XOOPIC, which is time explicit, fully electromagnetic, and capable of running on massively parallel supercomputers. Simulations of laser-driven wakefields with low ({approx}10{sup 16} W/cm{sup 2}) and high ({approx}10{sup 18} W/cm{sup 2}) peak intensity laser pulses are conducted in slab geometry, showing agreement with theory and fluid simulations. Simulations of the E-157 beam wakefield experiment at the Stanford Linear Accelerator Center, in which a 30 GeV electron beam passes through 1 m of preionized lithium plasma, are conducted in cylindrical geometry, obtaining good agreement with previous work. We briefly describe some of the more significant modifications of XOOPIC required by this work, and summarize the issues relevant to modeling relativistic electron-neutral collisions in a particle-in-cell code.

  12. A Particle In Cell code development for high current ion beam transport and plasma simulations

    CERN Document Server

    Joshi, N

    2016-01-01

    A simulation package employing a Particle in Cell (PIC) method is developed to study the high current beam transport and the dynamics of plasmas. This package includes subroutines those are suited for various planned projects at University of Frankfurt. In the framework of the storage ring project (F8SR) the code was written to describe the beam optics in toroidal magnetic fields. It is used to design an injection system for a ring with closed magnetic field lines. The generalized numerical model, in Cartesian coordinates is used to describe the intense ion beam transport through the chopper system in the low energy beam section of the FRANZ project. Especially for the chopper system, the Poisson equation is implemented with irregular geometries. The Particle In Cell model is further upgraded with a Monte Carlo Collision subroutine for simulation of plasma in the volume type ion source.

  13. Charged particle flows in an explosively generated non-ideal plasma

    Science.gov (United States)

    Boswell, C. J.; Carney, J. R.; Wilkinson, J.; Pangilinan, G. I.; Whitley, V. H.

    2007-06-01

    Non-ideal plasmas occur as a result of the stimulation of matter by strong shocks, detonation waves, or concentrated laser irradiation. Since all of these methods of generating non-ideal plasmas are already in use to address other problems, we focus on a detailed understanding of this plasma. In particular, we study the flow of charged particles in a non-ideal plasma generated using an explosive to compress the gas into the non- ideal plasma state. The shock wave in the gas is generated by an explosive located at one end of a guide tube filled with the gas. The detonation produces a shock wave strong enough to ionize the gas. Spectral line emission profiles, recorded with a streak emission spectroscopy system, are used to ascertain neutral and ionized gas properties. The electric and magnetic fields are measured by electrostatic probes and magnetic induction coils which permit the measurement of the temperature, density, and electric potential of the non-ideal plasma; as well as the flow of net electric charges respectively. The results demonstrate that a separation of the positive and negative charges occurs in the vicinity of the shock wave.

  14. Equation of State of the Quark Gluon Plasma within the Quasi-particle Approach

    CERN Document Server

    Begun, Viktor V; Mogilevsky, Oleg A

    2010-01-01

    We propose simple analytical form of the quark-gluon plasma (QGP) equation of state (EoS) based on a quasi-particle approach. This new EoS satisfies all qualitative features observed in the lattice QCD calculations and gives a good quantitative description of the lattice results in SU(3) gluodynamics. The suggested EoS opens up new possibilities for hydrodynamic and kinetic phenomenological applications in the studies of the QGP.

  15. Particle Simulation Code for the Electron Temperature Gradient Instability in Tokamak Toroidal Plasmas

    Institute of Scientific and Technical Information of China (English)

    JIANGuangde; DONGJiaqi

    2003-01-01

    A numerical simulation code has been established with particle simulation method in order to study the gyro-kinetic equations for the electrostatic electron temperature gradient modes in toroidal plasmas. The flowchart is given as well for the code. The fourth-order adaptive step-size scheme is adopted, that saves computer time and is simple. The calculation code is useful for the research of the electron temperature gradient instability.

  16. Formating double layer mechanism by electric charged particle stream in plasma

    Science.gov (United States)

    Shan-jun, Ma; Qian-li, Yang; Xiao-qing, Li

    1998-08-01

    In this paper, two-fluid equations have been solved after having considered magnetic field generated by charged particle stream. Finally, the distribution of electric field Ez(z, r) and its growth rate γ in plasma have been obtained. From the expression of Ez(z, r) it can be known that the double layer has been formed. With the increase of disturbance γ will be larger, and finally this will result in the interruption of electric current and occurrence of burst.

  17. A theory of two-beam acceleration of charged particles in a plasma waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Ostrovsky, A.O. [Kharkov Inst. of Physics and Technology (Ukraine)

    1993-11-01

    The progress made in recent years in the field of high-current relativistic electron beam (REB) generation has aroused a considerable interest in studying REB potentialities for charged particle acceleration with a high acceleration rate T = 100MeV/m. It was proposed, in particular, to employ high-current REB in two-beam acceleration schemes (TBA). In these schemes high current REB (driving beam) excites intense electromagnetic waves in the electrodynamic structure which, in their turn, accelerate particles of the other beam (driven beam). The TBA schemes can be divided into two groups. The first group includes the schemes, where the two beams (driving and driven) propagate in different electrodynamic structures coupled with each other through the waveguides which ensure the microwave power transmission to accelerate driven beam particles. The second group includes the TBA schemes, where the driving and driven beams propagate in one electrodynamic structure. The main aim of this work is to demonstrate by theory the possibility of realizing effectively the TBA scheme in the plasma waveguide. The physical model of the TBA scheme under study is formulated. A set of equations describing the excitation of RF fields by a high-current REB and the acceleration of driven beam electrons is also derived. Results are presented on the the linear theory of plasma wave amplification by the driving beam. The range of system parameters, at which the plasma-beam instability develops, is defined. Results of numerical simulation of the TBA scheme under study are also presented. The same section gives the description of the dynamics of accelerated particle bunching in the high-current REB-excited field. Estimates are given for the accelerating field intensities in the plasma and electron acceleration rates.

  18. Reactivation from latency displays HIV particle budding at plasma membrane, accompanying CD44 upregulation and recruitment

    Directory of Open Access Journals (Sweden)

    Sano Kouichi

    2009-07-01

    Full Text Available Abstract Background It has been accepted that HIV buds from the cell surface in T lymphocytes, whereas in macrophages it buds into intracellular endosomes. Recent studies, on the other hand, suggest that HIV preferentially buds from the cell surface even in monocytic cells. However, most studies are based on observations in acutely infected cells and little is known about HIV budding concomitant with reactivation from latency. Such studies would provide a better understanding of a reservoir for HIV. Results We observed HIV budding in latently infected T lymphocytic and monocytic cell lines following TNF-α stimulation and examined the upregulation of host factors that may be involved in particle production. Electron microscopy analysis revealed that reactivation of latently infected J1.1 cells (latently infected Jurkat cells with HIV-1 and U1 cells (latently infected U937 cells with HIV-1 displayed HIV particle budding predominantly at the plasma membrane, a morphology that is similar to particle budding in acutely infected Jurkat and U937 cells. When mRNA expression levels were quantified by qRT-PCR, we found that particle production from reactivated J1.1 and U1 cells was accompanied by CD44 upregulation. This upregulation was similarly observed when Jurkat and U937 cells were acutely infected with HIV-1 but not when just stimulated with TNF-α, suggesting that CD44 upregulation was linked with HIV production but not with cell stimulation. The molecules in endocytic pathways such as CD63 and HRS were also upregulated when U1 cells were reactivated and U937 cells were acutely infected with HIV-1. Confocal microscopy revealed that these upregulated host molecules were recruited to and accumulated at the sites where mature particles were formed at the plasma membrane. Conclusion Our study indicates that HIV particles are budded at the plasma membrane upon reactivation from latency, a morphology that is similar to particle budding in acute

  19. Relativistic magnetic reconnection in collisionless ion-electron plasmas explored with particle-in-cell simulations

    CERN Document Server

    Melzani, Mickaël; Folini, Doris; Winisdoerffer, Christophe; Favre, Jean M

    2014-01-01

    Magnetic reconnection is a leading mechanism for magnetic energy conversion and high-energy non-thermal particle production in a variety of high-energy astrophysical objects, including ones with relativistic ion-electron plasmas (e.g., microquasars or AGNs) - a regime where first principle studies are scarce. We present 2D particle-in-cell (PIC) simulations of low $\\beta$ ion-electron plasmas under relativistic conditions, i.e., with inflow magnetic energy exceeding the plasma rest-mass energy. We identify outstanding properties: (i) For relativistic inflow magnetizations (here $10 80$), the reconnection electric field is sustained more by bulk inertia than by thermal inertia. It challenges the thermal-inertia-paradigm and its implications. (iii) The inflows feature sharp transitions at the entrance of the diffusion zones. These are not shocks but results from particle ballistic motions, all bouncing at the same location, provided that the thermal velocity in the inflow is far smaller than the inflow E cross...

  20. Particle-in-cell investigation on the resonant absorption of a plasma surface wave

    Institute of Scientific and Technical Information of China (English)

    Lan Chao-Hui; Hu Xi-Wei

    2011-01-01

    The resonant absorption of a plasma surface wave is supposed to be an important and efficient mechanism of power deposition for a surface wave plasma source.In this paper,by using the particle-in-cell method and Monte Carlo simulation,the resonance absorption mechanism is investigated.Simulation results demonstrate the existence of surface wave resonance and show the high efficiency of heating electrons.The positions of resonant points,the resonance width and the spatio-temporal evolution of the resonant electric field are presented,which accord well with the theoretical results.The paper also discusses the effect of pressure on the resonance electric field and the plasma density.

  1. Electron temperature anisotropy in an expanding plasma: Particle-in-Cell simulations

    CERN Document Server

    Camporeale, Enrico; 10.1088/0004-637X/710/2/1848

    2010-01-01

    We perform fully-kinetic particle-in-cell simulations of an hot plasma that expands radially in a cylindrical geometry. The aim of the paper is to study the consequent development of the electron temperature anisotropy in an expanding plasma flow as found in a collisionless stellar wind. Kinetic plasma theory and simulations have shown that the electron temperature anisotropy is controlled by fluctuations driven by electromagnetic kinetic instabilities. In this study the temperature anisotropy is driven self-consistently by the expansion. While the expansion favors an increase of parallel anisotropy ($T_\\parallel>T_\\perp$), the onset of the firehose instability will tend to decrease it. We show the results for a supersonic, subsonic, and static expansion flows, and suggest possible applications of the results for the solar wind and other stellar winds.

  2. Modeling laser produced plasmas with smoothed particle hydrodynamics for next generation advanced light sources

    Science.gov (United States)

    Holladay, Robert; Griffith, Alec; Murillo, Michael S.

    2016-10-01

    A computational model has been developed to study the evolution of a plasma generated by next-generation advanced light sources such as SLAC's LCLS and LANL's proposed MaRIE. Smoothed Particle Hydrodynamics (SPH) is used to model the plasma evolution because of the ease with which it handles the open boundary conditions and large deformations associated with these experiments. Our work extends the basic SPH method by utilizing a two-fluid model of an electron-ion plasma that also incorporates time dependent ionization and recombination by allowing the SPH fluid particles to have an evolving mass based on the mean ionization state of the plasma. Additionally, inter-species heating, thermal conduction, and electric fields are also accounted for. The effects of various initial conditions and model parameters will be presented, with the goal of using this framework to develop a model that can be used in the design and interpretation of future experiments. This work was supported by the Los Alamos National Laboratory Computational Physics Workshop.

  3. Impurity identifications, concentrations and particle fluxes from spectral measurements of the EXTRAP T2R plasma

    Science.gov (United States)

    Menmuir, S.; Kuldkepp, M.; Rachlew, E.

    2006-10-01

    An absolute intensity calibrated 0.5 m spectrometer with optical multi-channel analyser detector was used to observe the visible-UV radiation from the plasma in the EXTRAP T2R reversed field pinch experiment. Spectral lines were identified indicating the presence of oxygen, chromium, iron and molybdenum impurities in the hydrogen plasma. Certain regions of interest were examined in more detail and at different times in the plasma discharge. Impurity concentration calculations were made using the absolute intensities of lines of OIV and OV measured at 1-2 ms into the discharge generating estimates of the order of 0.2% of ne in the central region rising to 0.7% of ne at greater radii for OIV and 0.3% rising to 0.6% for OV. Edge electron temperatures of 0.5-5 eV at electron densities of 5-10×1011 cm-3 were calculated from the measured relative intensities of hydrogen Balmer lines. The absolute intensities of hydrogen lines and of multiplets of neutral chromium and molybdenum were used to determine particle fluxes (at 4-5 ms into the plasma) of the order 1×1016, 7×1013 and 3×1013 particles cm-2 s-1, respectively.

  4. Particle Simulation of the Blob Propagation in Non-Uniform Plasmas

    Science.gov (United States)

    Hasegawa, Hiroki; Ishiguro, Seiji

    2014-10-01

    The kinetic dynamics on blob propagation in non-uniform plasmas have been studied with a three dimensional electrostatic plasma particle simulation code. In our previous studies, we assumed that grad-B is uniform in the toroidal and poloidal directions. In scrape-off layer (SOL) plasmas of real magnetic confinement devices, however, the direction of grad-B is different between the inside and the outside of torus. In this study, we have investigated the blob kinetic dynamics in the system where grad-B is spatially non-uniform. We observe different potential and particle flow structures from those shown in our previous studies. Thus, it is found that propagation properties of blobs in non-uniform grad-B plasmas are also distinct. These properties depend on the initial blob location in the toroidal directions. We will also discuss the application of this study to pellet dynamics. Supported by NIFS Collaboration Research programs (NIFS13KNSS038 and NIFS14KNXN279) and a Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science (KAKENHI 23740411).

  5. Trapped ions and the shielding of dust particles in low-density non-equilibrium plasma of glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Sukhinin, Gennady; Fedoseev, Alexander [Institute of Thermophysics SB RAS, Ave. Lavrentyev, 1, Novosibirsk 630090 (Russian Federation); Antipov, Sergei; Petrov, Oleg; Fortov, Vladimir [Joint Institute for High Temperatures RAS, Izhorskaya 13/19, Moscow 127412 (Russian Federation)], E-mail: sukhinin@itp.nsc.ru

    2009-05-29

    A new model for the formation of trapped ions around a negatively charged dust particle immersed in low-density non-equilibrium plasma of gas discharge is presented. It is shown that the ionic coat leads to a shielding of the proper charge of the dust particle. In experiments it is only possible to detect the effective charge of a dust particle that is equal to the difference between the proper charge of the particle and the charge of trapped ion000.

  6. Boundary Layer Flow and Heat Transfer of fluid particle suspension with nanoparticles over a nonlinear stretching sheet embedded in a porous medium

    Science.gov (United States)

    Prasannakumara, B. C.; Shashikumar, N. S.; Venkatesh, P.

    2017-09-01

    An analysis has been carried out to study the effect of nonlinear thermal radiation on slip flow and heat transfer of fluid particle suspension with nanoparticles over a nonlinear stretching sheet immersed in a porous medium. Water is considered as a base fluid with dust particles along with suspended Aluminum Oxide (Al2O3) nanoparticles. Using appropriate similarity transformations, the coupled nonlinear partial differential equations are reduced into a set of coupled nonlinear ordinary differential equations. The reduced equations are then solved numerically using Runge-Kutta-Fehlberg45 order method with the help of shooting technique to investigate the impact of various pertinent parameters for the velocity and temperature fields. The obtained results are presented in tabular form as well as graphically and discussed in detail. Effect of different parameters on skin friction coefficient and Nusselt number are also discussed.

  7. Automated detection and analysis of particle beams in laser-plasma accelerator simulations

    Energy Technology Data Exchange (ETDEWEB)

    Ushizima, Daniela Mayumi; Geddes, C.G.; Cormier-Michel, E.; Bethel, E. Wes; Jacobsen, J.; Prabhat, ,; R.ubel, O.; Weber, G,; Hamann, B.

    2010-05-21

    Numerical simulations of laser-plasma wakefield (particle) accelerators model the acceleration of electrons trapped in plasma oscillations (wakes) left behind when an intense laser pulse propagates through the plasma. The goal of these simulations is to better understand the process involved in plasma wake generation and how electrons are trapped and accelerated by the wake. Understanding of such accelerators, and their development, offer high accelerating gradients, potentially reducing size and cost of new accelerators. One operating regime of interest is where a trapped subset of electrons loads the wake and forms an isolated group of accelerated particles with low spread in momentum and position, desirable characteristics for many applications. The electrons trapped in the wake may be accelerated to high energies, the plasma gradient in the wake reaching up to a gigaelectronvolt per centimeter. High-energy electron accelerators power intense X-ray radiation to terahertz sources, and are used in many applications including medical radiotherapy and imaging. To extract information from the simulation about the quality of the beam, a typical approach is to examine plots of the entire dataset, visually determining the adequate parameters necessary to select a subset of particles, which is then further analyzed. This procedure requires laborious examination of massive data sets over many time steps using several plots, a routine that is unfeasible for large data collections. Demand for automated analysis is growing along with the volume and size of simulations. Current 2D LWFA simulation datasets are typically between 1GB and 100GB in size, but simulations in 3D are of the order of TBs. The increase in the number of datasets and dataset sizes leads to a need for automatic routines to recognize particle patterns as particle bunches (beam of electrons) for subsequent analysis. Because of the growth in dataset size, the application of machine learning techniques for

  8. Treatment of airborne asbestos and asbestos-like microfiber particles using atmospheric microwave air plasma.

    Science.gov (United States)

    Averroes, A; Sekiguchi, H; Sakamoto, K

    2011-11-15

    Atmospheric microwave air plasma was used to treat asbestos-like microfiber particles that had two types of ceramic fiber and one type of stainless fiber. The treated particles were characterized via scanning electron microscopy (SEM) and X-ray diffraction (XRD). The experiment results showed that one type of ceramic fiber (Alumina:Silica=1:1) and the stainless fiber were spheroidized, but the other type of ceramic fiber (Alumina:Silica=7:3) was not. The conversion of the fibers was investigated by calculating the equivalent diameter, the aspect ratio, and the fiber content ratio. The fiber content ratio in various conditions showed values near zero. The relationship between the normalized fiber vanishing rate and the energy needed to melt the particles completely per unit surface area of projected particles, which is defined as η, was examined and seen to indicate that the normalized fiber vanishing rate decreased rapidly with the increase in η. Finally, some preliminary experiments for pure asbestos were conducted, and the analysis via XRD and phase-contrast microscopy (PCM) showed the availability of the plasma treatment.

  9. Time-Dependent Stochastic Particle Acceleration in Astrophysical Plasmas: Exact Solutions Including Momentum-Dependent Escape

    CERN Document Server

    Becker, P A; Le, T

    2006-01-01

    Stochastic acceleration of charged particles due to interactions with magnetohydrodynamic (MHD) plasma waves is the dominant process leading to the formation of the high-energy electron and ion distributions in a variety of astrophysical systems. Collisions with the waves influence both the energization and the spatial transport of the particles, and therefore it is important to treat these two aspects of the problem in a self-consistent manner. We solve the representative Fokker-Planck equation to obtain a new, closed-form solution for the time-dependent Green's function describing the acceleration and escape of relativistic ions interacting with Alfven or fast-mode waves characterized by momentum diffusion coefficient $D(p)\\propto p^q$ and mean particle escape timescale $t_esc(p) \\propto p^{q-2}$, where $p$ is the particle momentum and $q$ is the power-law index of the MHD wave spectrum. In particular, we obtain solutions for the momentum distribution of the ions in the plasma and also for the momentum dist...

  10. Isotope ratio analysis of individual sub-micrometer plutonium particles with inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Esaka, Fumitaka; Magara, Masaaki; Suzuki, Daisuke; Miyamoto, Yutaka; Lee, Chi-Gyu; Kimura, Takaumi

    2010-12-15

    Information on plutonium isotope ratios in individual particles is of great importance for nuclear safeguards, nuclear forensics and so on. Although secondary ion mass spectrometry (SIMS) is successfully utilized for the analysis of individual uranium particles, the isobaric interference of americium-241 to plutonium-241 makes difficult to obtain accurate isotope ratios in individual plutonium particles. In the present work, an analytical technique by a combination of chemical separation and inductively coupled plasma mass spectrometry (ICP-MS) is developed and applied to isotope ratio analysis of individual sub-micrometer plutonium particles. The ICP-MS results for individual plutonium particles prepared from a standard reference material (NBL SRM-947) indicate that the use of a desolvation system for sample introduction improves the precision of isotope ratios. In addition, the accuracy of the (241)Pu/(239)Pu isotope ratio is much improved, owing to the chemical separation of plutonium and americium. In conclusion, the performance of the proposed ICP-MS technique is sufficient for the analysis of individual plutonium particles.

  11. Multifield measurement of magnetic fluctuation-induced particle flux in a high-temperature toroidal plasma

    Science.gov (United States)

    Lin, L.; Ding, W. X.; Brower, D. L.

    2016-12-01

    Magnetic fluctuation-induced particle transport is explored in the high-temperature, high-beta interior of the Madison symmetric torus (MST) reversed-field pinch by performing a multifield measurement of the correlated product of magnetic and density fluctuations associated with global resistive tearing modes. Local density fluctuations are obtained by inverting the line-integrated interferometry data after resolving the mode helicity through correlation techniques. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of Faraday-effect polarimetry measurements. Reconstructed 2D images of density and current density perturbations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved. The convective magnetic fluctuation-induced particle flux profile is measured for both standard and high-performance plasmas in MST with tokamak-like confinement, showing large reduction in the flux during improved confinement.

  12. Fokker Planck kinetic modeling of suprathermal alpha-particles in a fusion plasma

    CERN Document Server

    Peigney, Benjamin-Edouard; Tikhonchuk, Vladimir

    2014-01-01

    We present an ion kinetic model describing the ignition and burn of the deuterium-tritium fuel of inertial fusion targets. The analysis of the underlying physical model enables us to develop efficient numerical methods to simulate the creation, transport and collisional relaxation of fusion reaction products (alpha-particles) at a kinetic level. A two-energy-scale approach leads to a self-consistent modeling of the coupling between suprathermal alpha-particles and the thermal bulk of the imploding plasma. This method provides an accurate numerical treatment of energy deposition and transport processes involving suprathermal particles. The numerical tools presented here are validated against known analytical results. This enables us to investigate the potential role of ion kinetic effects on the physics of ignition and thermonuclear burn in inertial confinement fusion schemes.

  13. Numerical Simulation and Experimental Investigation of Multi-function Micro-plasma Jet and Alumina Particle Behaviour

    Directory of Open Access Journals (Sweden)

    Liu Gu

    2016-01-01

    Full Text Available Turbulent flow in multi-function micro-plasma spray, as well as the trajectories and state-changing course of alumina particles in the plasma jet were simulated. The distribution of temperature and velocity of the plasma jet and in-flight alumina particles is discussed. Calculations show that particles are heated and accelerated sufficiently by the plasma flame due to a longer travel time than that of external injection system, therefore, possess higher temperature and velocity. Alumina particles temperature and velocity increase rapidly along the jet axis at the initial stage, but then decrease gradually. The velocity and surface temperature of in-flight alumina particles are measured by Spray Watch-2i system. The velocity and surface temperature of alumina particles measured agree well with the simulation results, confirming that the simulation model is suitable for the prediction of the turbulent flow and the particle characteristics, which also reveals the superiority of the plasma spray gun in this multi-function micro-plasma spraying system.

  14. Acceleration of a Particle-in-Cell Code for Space Plasma Simulations with OpenACC

    Science.gov (United States)

    Peng, Ivy Bo; Markidis, Stefano; Vaivads, Andris; Vencels, Juris; Deca, Jan; Lapenta, Giovanni; Hart, Alistair; Laure, Erwin

    2015-04-01

    We simulate space plasmas with the Particle-in-cell (PIC) method that uses computational particles to mimic electrons and protons in solar wind and in Earth magnetosphere. The magnetic and electric fields are computed by solving the Maxwell's equations on a computational grid. In each PIC simulation step, there are four major phases: interpolation of fields to particles, updating the location and velocity of each particle, interpolation of particles to grids and solving the Maxwell's equations on the grid. We use the iPIC3D code, which was implemented in C++, using both MPI and OpenMP, for our case study. By November 2014, heterogeneous systems using hardware accelerators such as Graphics Processing Unit (GPUs) and the Many Integrated Core (MIC) coprocessors for high performance computing continue growth in the top 500 most powerful supercomputers world wide. Scientific applications for numerical simulations need to adapt to using accelerators to achieve portability and scalability in the coming exascale systems. In our work, we conduct a case study of using OpenACC to offload the computation intensive parts: particle mover and interpolation of particles to grids, in a massively parallel Particle-in-Cell simulation code, iPIC3D, to multi-GPU systems. We use MPI for inter-node communication for halo exchange and communicating particles. We identify the most promising parts suitable for GPUs accelerator by profiling using CrayPAT. We implemented manual deep copy to address the challenges of porting C++ classes to GPU. We document the necessary changes in the exiting algorithms to adapt for GPU computation. We present the challenges and findings as well as our methodology for porting a Particle-in-Cell code to multi-GPU systems using OpenACC. In this work, we will present the challenges, findings and our methodology of porting a Particle-in-Cell code for space applications as follows: We profile the iPIC3D code by Cray Performance Analysis Tool (CrayPAT) and identify

  15. Full-Particle Simulations on Electrostatic Plasma Environment near Lunar Vertical Holes

    Science.gov (United States)

    Miyake, Y.; Nishino, M. N.

    2015-12-01

    The Kaguya satellite and the Lunar Reconnaissance Orbiter have observed a number of vertical holes on the terrestrial Moon [Haruyama et al., GRL, 2009; Robinson et al., PSS, 2012], which have spatial scales of tens of meters and are possible lava tube skylights. The hole structure has recently received particular attention, because the structure gives an important clue to the complex volcanic history of the Moon. The holes also have high potential as locations for constructing future lunar bases, because of fewer extra-lunar rays/particles and micrometeorites reaching the hole bottoms. In this sense, these holes are not only interesting in selenology, but are also significant from the viewpoint of electrostatic environments. The subject can also be an interesting resource of research in comparative planetary science, because hole structures have been found in other solar system bodies such as the Mars. The lunar dayside electrostatic environment is governed by electrodynamic interactions among the solar wind plasma, photoelectrons, and the charged lunar surface, providing topologically complex boundaries to the plasma. We use the three-dimensional, massively-parallelized, particle-in-cell simulation code EMSES [Miyake and Usui, POP, 2009] to simulate the near-hole plasma environment on the Moon [Miyake and Nishino, Icarus, 2015]. We took into account the solar wind plasma downflow, photoelectron emission from the sunlit part of the lunar surface, and plasma charge deposition on the surface. The simulation domain consists of 400×400×2000 grid points and contains about 25 billion plasma macro-particles. Thus, we need to use supercomputers for the simulations. The vertical wall of the hole introduces a new boundary for both photo and solar wind electrons. The current balance condition established at a hole bottom is altered by the limited solar wind electron penetration into the hole and complex photoelectron current paths inside the hole. The self

  16. Plasma and BIAS Modeling: Self-Consistent Electrostatic Particle-in-Cell with Low-Density Argon Plasma for TiC

    Directory of Open Access Journals (Sweden)

    Jürgen Geiser

    2011-01-01

    processes. In this paper we present a new model taken into account a self-consistent electrostatic-particle in cell model with low density Argon plasma. The collision model are based of Monte Carlo simulations is discussed for DC sputtering in lower pressure regimes. In order to simulate transport phenomena within sputtering processes realistically, a spatial and temporal knowledge of the plasma density and electrostatic field configuration is needed. Due to relatively low plasma densities, continuum fluid equations are not applicable. We propose instead a Particle-in-cell (PIC method, which allows the study of plasma behavior by computing the trajectories of finite-size particles under the action of an external and self-consistent electric field defined in a grid of points.

  17. Rotating structures in low temperature magnetized plasmas - Insight from particle simulations

    Directory of Open Access Journals (Sweden)

    Jean-Pierre eBoeuf

    2014-12-01

    Full Text Available The EXB configuration of various low temperature plasma devices is often responsible for the formation of rotating structures and instabilities leading to anomalous electron transport across the magnetic field. In these devices, electrons are strongly magnetized while ions are weakly or not magnetized and this leads to specific physical phenomena that are not present in fusion plasmas where both electrons and ions are strongly magnetized. In this paper we describe basic phenomena involving rotating plasma structures in simple configurations of low temperature EXB plasma devices on the basis of PIC-MCC (Particle-In-Cell Monte Carlo Collisions simulations. We focus on three examples: rotating electron vortices and rotating spokes in cylindrical magnetrons, and azimuthal electron-cyclotron drift instability in Hall thrusters. The simulations are not intended to give definite answers to the many physics issues related to low temperature EXB plasma devices but are used to illustrate and discuss some of the basic questions that need further studies.

  18. Solid-particle erosion in the tube end of the tube sheet of a shell-and-tube heat exchanger

    Science.gov (United States)

    Habib, M. A.; Badr, H. M.; Said, S. A. M.; Ben-Mansour, R.; Al-Anizi, S. S.

    2006-03-01

    Erosion is one of the major problems in many industrial processes, and in particular, in heat exchangers. The effects of flow velocity and sand particle size on the rate of erosion in a typical shell-and-tube heat exchanger were investigated numerically using the Lagrangian particle-tracking method. Erosion and penetration rates were obtained for sand particles of diameters ranging from 10 to 500 μm and for inlet flow velocities ranging from 0.197 to 2.95 m/s. A flow visualization experiment was conducted with the objective of verifying the accuracy of the continuous phase calculation procedure. Comparison with available experimental data of penetration rates was also conducted. These comparisons resulted in a good agreement. The results show that the location and number of eroded tubes depend mainly on the particle size and velocity magnitude at the header inlet. The rate of erosion depends exponentially on the velocity. The particle size shows negligible effect on the erosion rate at high velocity values and the large-size particles show less erosion rates compared to the small-size particles at low values of inlet flow velocities. The results indicated that the erosion and penetration rates are insignificant at the lower end of the velocity range. However, these rates were found to increase continuously with the increase of the inlet flow velocity for all particle sizes. The particle size creating the highest erosion rate was found to depend on the flow velocity range.

  19. Elemental Quantitative Distribution and Statistical Analysis on Cross Section of Stainless Steel Sheet by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    Qian-hua LUO; Hai-zhou WANG

    2015-01-01

    An innovative application of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) technique in illustrating elemental distributions on stainless steel sheets was presented. The technique proved to be a systematic and accurate ap-proach in producing visual images or maps of elemental distributions at cross-sectional surface of a stainless steel sheet. Two stain-less steel sheets served as research objects: 3 mm×1 300 mm hot-rolled stainless steel plate and 1 mm×1 260 mm cold-rolled plate. The cross-sectional surfaces of the two samples at 1/4 position along the width direction were scanned (raster area-44 mm2 and 11 mm2) with a focused laser beam (wavelength 213 nm, diameter of laser crater 100 μm, and laser power 1.6 mJ) in a laser abla-tion chamber. The laser ablation system was coupled to a quadrupole ICP-MS, which made the detection of ion intensities of27Al+, 44Ca+,47Ti+,55Mn+ and56Fe+ within an area of interest possible. One-dimensional (1D) content line distribution maps and two-dimensional (2D) contour maps for speciifc positions or areas were plotted to indicate the element distribution of a target area with high accuracy. Statistic method was used to analyze the acquired data by calculating median contents, maximum segregation, sta-tistic segregation and content-frequency distribution.

  20. Numerical Modeling and Analysis of Space-Based Electric Antennas via Plasma Particle Simulation

    Science.gov (United States)

    Miyake, Y.; Usui, H.; Kojima, H.

    2009-12-01

    Better understanding of electric antenna properties (e.g., impedance) in space plasma environment is necessitated, because calibration of electric field data obtained by scientific spacecraft should be done with precise knowledge about the properties. Particularly, a strong demand arises regarding a sophisticated method for evaluating modern electric field instrument properties toward future magnetospheric missions. However, due to complex behavior of surrounding plasmas, it is often difficult to apply theoretical approaches to the antenna analysis including the plasma kinetic effects and the complex structure of such instruments. For the self-consistent antenna analysis, we have developed a new electromagnetic (EM) particle simulation code named EMSES. The code is based on the particle-in-cell technique and also supports a treatment of inner boundaries describing spacecraft conductive surfaces. This enables us to naturally include the effects of the inhomogeneous plasma environment such as a plasma and photoelectron sheaths created around the antenna. The support of the full EM treatment is also important to apply our tool to antenna properties for not only electrostatic (ES) but also EM plasma waves. In the current study, we particularly focus on an electric field instrument MEFISTO, which is designed for BepiColombo/MMO to the Mercury orbit. For the practical analysis of MEFISTO electric properties, it is important to consider an ES environment affected by the instrument body potential and the photoelectron distribution. We present numerical simulations on an ES structure around MEFISTO as well as current-voltage characteristic of the instrument. We have also started numerical modeling of a photoelectron guard electrode, which is one of key technologies for producing an optimal condition of plasma environment around the instrument. We have modeled a pre-amplifier housing called “puck”, the surface of which functions as the electrode. The photoelectron guard

  1. Fast Light-Sheet Scanner

    Science.gov (United States)

    Hunter, William W., Jr.; Humphreys, William M., Jr.; Bartram, Scott M.

    1995-01-01

    Optomechanical apparatus maintains sheet of pulsed laser light perpendicular to reference axis while causing sheet of light to translate in oscillatory fashion along reference axis. Produces illumination for laser velocimeter in which submicrometer particles entrained in flow illuminated and imaged in parallel planes displaced from each other in rapid succession. Selected frequency of oscillation range upward from tens of hertz. Rotating window continuously shifts sheet of light laterally while maintaining sheet parallel to same plane.

  2. Detection of thin current sheets and associated reconnection in the Earth's turbulent magnetosheath using cluster multi-point measurements

    Science.gov (United States)

    Chasapis, Alexandros; Retino, Alessandro; Sahraoui, Fouad; Greco, Antonella; Vaivads, Andris; Sundkvist, David; Canu, Patrick

    2013-04-01

    Magnetic reconnection occurs in turbulent plasma within a large number of volume-filling thin current sheets and is one major candidate for energy dissipation of turbulent plasma. Such dissipation results in particle heating and non-thermal particle acceleration. In situ observations are needed to study the detailed properties of thin current sheets and associated reconnection, in order to determine its importance as a dissipation mechanism at small scales. In particular, multi-point measurements are crucial to unambiguously identify spatial scales (e.g current sheet thickness) and estimate key quantities such as E*J. Here we present a study of the properties of thin current sheets detected in the Earths magnetosheath downstream of the quasi-parallel shock by using Cluster spacecraft data. The current sheets were detected by the rotation of the magnetic field as computed by four-point measurements. We study the distribution of current sheets as a function of the magnetic shear angle θ, their duration and the waiting time between consecutive current sheets. We found that high shear (θ > 90 degrees) current sheets show different properties with respect to low shear current sheets (θ < 90 degrees). These high-shear current sheets account for about ˜ 20% of the total and have an average thickness comparable to the ion inertial length. We also compare our four-point detection method with other single-point methods (e.g. Partial Variance of Increments - PVI) and we discuss the results of such comparison.

  3. Particle-in-Cell Laser-Plasma Simulation on Xeon Phi Coprocessors

    CERN Document Server

    Surmin, I A; Efimenko, E S; Gonoskov, A A; Korzhimanov, A V; Meyerov, I B

    2015-01-01

    This paper concerns development of a high-performance implementation of the Particle-in-Cell method for plasma simulation on Intel Xeon Phi coprocessors. We discuss suitability of the method for Xeon Phi architecture and present our experience of porting and optimization of the existing parallel Particle-in-Cell code PICADOR. Direct porting with no code modification gives performance on Xeon Phi close to 8-core CPU on a benchmark problem with 50 particles per cell. We demonstrate step-by-step application of optimization techniques such as improving data locality, enhancing parallelization efficiency and vectorization that leads to 3.75 x speedup on CPU and 7.5 x on Xeon Phi. The optimized version achieves 18.8 ns per particle update on Intel Xeon E5-2660 CPU and 9.3 ns per particle update on Intel Xeon Phi 5110P. On a real problem of laser ion acceleration in targets with surface grating that requires a large number of macroparticles per cell the speedup of Xeon Phi compared to CPU is 1.6 x.

  4. Roles of charged particles and reactive species on cell membrane permeabilization induced by atmospheric-pressure plasma irradiation

    Science.gov (United States)

    Sasaki, Shota; Kanzaki, Makoto; Hokari, Yutaro; Tominami, Kanako; Mokudai, Takayuki; Kanetaka, Hiroyasu; Kaneko, Toshiro

    2016-07-01

    As factors that influence cell membrane permeabilization during direct and indirect atmospheric-pressure plasma irradiation, charged particle influx, superoxide anion radicals (O2 -•), and hydrogen peroxide (H2O2) in plasma-irradiated solution were evaluated. These are the three strong candidate factors and might multiply contribute to cell membrane permeabilization. In particular, a shorter plasma diffusion distance leads to the enhancement of the direct effects such as charged particle influx and further increase cell membrane permeability. In addition, O2 -• dissipates over time (a life span of the order of minutes) in plasma-irradiated water, and the deactivation of a plasma-irradiated solution in term of cell membrane permeabilization occurs in a life span of the same order. These results could promote the understanding of the mechanism of plasma-induced cell membrane permeabilization.

  5. Temperature of the Source Plasma in Gradual Solar Energetic Particle Events

    CERN Document Server

    Reames, Donald V

    2015-01-01

    Scattering, during interplanetary transport in large, "gradual" solar energetic-particle (SEP) events, can cause element abundance enhancements or suppressions that depend upon the mass-to-charge ratio A/Q of the ions as an increasing power law early in events and a decreasing power law of the residual ions later. Since the Q values for the ions depend upon the source plasma temperature T, best fits to the power-law dependence of enhancements vs. A/Q provide a fundamentally new method to determine the most probable value of T for these events. We find that fits to the times of increasing and decreasing powers give similar values of T, most commonly (69%) in the range of 0.8-1.6 MK, consistent with the acceleration of ambient coronal plasma by shock waves driven out from the Sun by coronal mass ejections (CMEs). However, 24% of the SEP events studied showed plasma of 2.5-3.2 MK, typical of that previously determined for the smaller impulsive SEP events; these particles may be reaccelerated preferentially by qu...

  6. Fluid and gyrokinetic modelling of particle transport in plasmas with hollow density profiles

    Science.gov (United States)

    Tegnered, D.; Oberparleiter, M.; Nordman, H.; Strand, P.

    2016-11-01

    Hollow density profiles occur in connection with pellet fuelling and L to H transitions. A positive density gradient could potentially stabilize the turbulence or change the relation between convective and diffusive fluxes, thereby reducing the turbulent transport of particles towards the center, making the fuelling scheme inefficient. In the present work, the particle transport driven by ITG/TE mode turbulence in regions of hollow density profiles is studied by fluid as well as gyrokinetic simulations. The fluid model used, an extended version of the Weiland transport model, Extended Drift Wave Model (EDWM), incorporates an arbitrary number of ion species in a multi-fluid description, and an extended wavelength spectrum. The fluid model, which is fast and hence suitable for use in predictive simulations, is compared to gyrokinetic simulations using the code GENE. Typical tokamak parameters are used based on the Cyclone Base Case. Parameter scans in key plasma parameters like plasma β, R/LT , and magnetic shear are investigated. It is found that β in particular has a stabilizing effect in the negative R/Ln region, both nonlinear GENE and EDWM show a decrease in inward flux for negative R/Ln and a change of direction from inward to outward for positive R/Ln . This might have serious consequences for pellet fuelling of high β plasmas.

  7. Time evolution of the particle and heat flux of the detached plasma

    Science.gov (United States)

    Pianpanit, Theerasarn; Ishiguro, Seiji; Hasegawa, Hiroki

    2016-10-01

    The detached plasma is a regime when the particle and heat flux of the plasma are largely reduced before reaching the divertor target. Linear devices experiment data show that when the neutral gas pressure in front of the target increases the heat flux to the target largely decreases. The 1D-3V particle simulation with Monte Carlo collision and cumulative scattering angle Coulomb collision has been developed to study the kinetic effect of the detached plasma. The simulation was performed with the constant temperature and pressure of neutral gas in front of the target. A large decrease in the electron temperature from 5eV to below 1 eV follows a large decrease in the ion temperature inside the neutral gas area in the case with high neutral gas pressure in front of the target. The energy flux at the target decreases in the process of attaining the detached state. This work was performed with the support and under the auspices of the NIFS Collaboration Research programs NIFS14KNXN279 and NIFS14KNSS059.

  8. A non-abelian quasi-particle model for gluon plasma

    Science.gov (United States)

    Politis, E. P.; Tsagkarakis, C. E.; Diakonos, F. K.; Maintas, X. N.; Tsapalis, A.

    2016-12-01

    We propose a quasi-particle model for the thermodynamic description of the gluon plasma which takes into account non-abelian characteristics of the gluonic field. This is accomplished utilizing massive non-linear plane wave solutions of the classical equations of motion with a variable mass parameter, reflecting the scale invariance of the Yang-Mills Lagrangian. For the statistical description of the gluon plasma we interpret these non-linear waves as quasi-particles with a temperature dependent mass distribution. Quasi-Gaussian distributions with a common variance but different temperature dependent mean masses for the longitudinal and transverse modes are employed. We use recent Lattice results to fix the mean transverse and longitudinal masses while the variance is fitted to the equation of state of pure SU (3) on the Lattice. Thus, our model succeeds to obtain both a consistent description of the gluon plasma energy density as well as a correct behavior of the mass parameters near the critical point.

  9. Mixed diffusive-convective relaxation of a broad beam of energetic particles in cold plasma

    CERN Document Server

    Carlevaro, Nakia; Falessi, Matteo V; Montani, Giovanni; Terzani, Davide; Zonca, Fulvio

    2015-01-01

    We revisit the applications of quasi-linear theory as a paradigmatic model for weak plasma turbulence and the associated bump-on-tail problem. The work, presented here, is built around the idea that large-amplitude or strongly shaped beams do not relax through diffusion only and that there exists an intermediate time scale where the relaxations are {\\it convective} (ballistic-like). We cast this novel idea in the rigorous form of a self-consistent nonlinear dynamical model, which generalizes the classic equations of the quasi-linear theory to "broad" beams with internal structure. We also present numerical simulation results of the relaxation of a broad beam of energetic particles in cold plasma. These generally demonstrate the mixed diffusive-convective features of supra-thermal particle transport; and essentially depend on nonlinear wave-particle interactions and phase-space structures. Taking into account modes of the stable linear spectrum is crucial for the self-consistent evolution of the distribution f...

  10. Particle-in-cell simulation of an electronegative plasma under direct current bias studied in a large range of electronegativity

    Energy Technology Data Exchange (ETDEWEB)

    Oudini, N. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Laboratoire des plasmas de Decharges, Centre de Developement des Technologies Avancees, Cite du 20 Aout BP 17 Baba Hassen, 16081 Algiers (Algeria); Raimbault, J.-L.; Chabert, P.; Aanesland, A. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Meige, A. [PRESANS / X-Technologies/Ecole Polytechnique, 91128 Palaiseau Cedex (France)

    2013-04-15

    A one-dimensional electronegative plasma situated between two symmetrical parallel electrodes under DC bias is studied by Particle-In-Cell simulation with Monte Carlo Collisions. By varying the electronegativity {alpha}{identical_to}n{sub -}/n{sub e} from the limit of electron-ion plasmas (negative ion free) to ion-ion plasmas (electron free), the sheaths formation, the negative ion flux flowing towards the electrodes, and the particle velocities at the sheath edges are investigated. Depending on {alpha}, it is shown that the electronegative plasma behavior can be described by four regimes. In the lowest regime of {alpha}, i.e., {alpha} < 50, negative ions are confined by two positive sheaths within the plasma, while in the higher regimes of {alpha}, a negative sheath is formed and the negative ion flux can be extracted from the bulk plasma. In the two intermediate regimes of {alpha}, i.e., 50 < {alpha} < 10{sup 5}, both the electron and the negative ion fluxes are involved in the neutralization of the positive ions flux that leaves the plasma. In particular, we show that the velocity of the negative ions entering the negative sheath is affected by the presence of the electrons, and is not given by the modified Bohm velocity generally accepted for electronegative plasmas. For extremely high electronegativity, i.e., {alpha} > 10{sup 5}, the presence of electrons in the plasma is marginal and the electronegative plasma can be considered as an ion-ion plasma (electron free).

  11. Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kaganovich, I.D.; Davidson, R.C.; Dorf, M.A.; Startsev, E.A.; Sefkow, A.B; Friedman, A.F.; Lee, E.P.

    2009-09-03

    Neutralization and focusing of intense charged particle beam pulses by a background plasma forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating

  12. Laser light scattering from silicon particles generated in an argon diluted silane plasma

    Science.gov (United States)

    Qin, Y.; Bilik, N.; Kortshagen, U. R.; Aydil, E. S.

    2016-03-01

    We conducted laser light scattering (LLS) measurements in a 13.56 MHz capacitively coupled dusty plasma maintained in silane and argon to study the spatial distribution of silicon nanoparticles and nanoparticle agglomerates. Specifically, we focused on the temporal evolution of their spatial distribution in the plasma as a function of pressure and power. We observed three distinct types of temporal evolution behavior of the nanoparticle dust cloud in the plasma and classified these into three regimes based on pressure and power. Each regime features a distinct pattern in laser light scattering measurements. At low pressures (˜80-100 mTorr) and high powers (˜40-60 W) we observed periodically repeating expansions and contractions of a continuous dust cloud for the first time. Dust voids, which have been reported before, were also observed at high pressures (˜100-150 mTorr) and low powers (˜20-40 W) in the center of the plasma. A mechanism is proposed to explain the observed dynamics of the nanoparticles. The balance between the ion drag force and electrostatic forces and their dependence on particle size are hypothesized to be the dominant factors that determine the nanoparticle cloud dynamics.

  13. Maximum available flux of charged particles from the laser ablation plasma

    Science.gov (United States)

    Sakai, Yasuo; Itagaki, Tomonobu; Horioka, Kazuhiko

    2016-12-01

    The laser ablation plasma was characterized for high-flux sources of ion and electron beams. An ablation plasma was biased to a positive or a negative high voltage, and the fluxes of charged particles through a pair of extraction electrodes were measured as a function of the laser intensity IL. Maximum available fluxes and the ratios of electron and ion beam currents Je/Ji were evaluated as a function of the laser irradiance. The ion and the electron fluxes increased with a laser intensity and the current ratio was around 40 at IL = 1.3 × 108 W/cm2 which monotonically decreased with an increase of the laser intensity. The current ratios Je/Ji were correlated to the parameters of ablation plasma measured by the electrostatic probes. The results showed that the ion fluxes are basically enhanced by super-sonically drifting ions in the plasma and the electron fluxes are also enhanced by the drift motion together with a reduction of the sheath potential due to the enhanced ion flux to the surrounding wall.

  14. Plasma Treatment of Polyethylene Powder Particles in Hollow Cathode Glow Discharge

    Science.gov (United States)

    Wolter, Matthias; Quitzau, Meike; Bornholdt, Sven; Kersten, Holger

    2008-09-01

    Polyethylen (PE) is widely used in the production of foils, insulators, packaging materials, plastic bottles etc. Untreated PE is hydrophobic due to its unpolar surface. Therefore, it is hard to print or glue PE and the surface has to be modified before converting. In the present experiments a hollow cathode glow discharge is used as plasma source which is mounted in a spiral conveyor in order to ensure a combines transport of PE powder particles. With this set-up a homogeneous surface treatment of the powder is possible while passing the glow discharge. The plasma treatment causes a remarkable enhancement of the hydrophilicity of the PE powder which can be verified by contact angle measurements and X-ray photoelectron spectroscopy.

  15. Mechanism and operation parameters of a plasma-driven micro-particle accelerator

    Institute of Scientific and Technical Information of China (English)

    HUANG JianGuo; FENG ChunHua; HAN dianWei; LI HongWei; CAI MingHui; LI XiaoYin; ZHANG ZhenLong; CHEN ZhaoFeng; WANG Long; YANG XuanZong

    2009-01-01

    There is a large amount of micro debris ranging between millimeters and micrometers in space, which has significant influence on the reliability and life of spacecrafts through long-duration integrated im-pacts and has to be considered in designing a vehicle's suitability to the space environment. In order to simulate the micro-impacts on exposed materials, a plasma-driven micro-particle accelerator was de-veloped. The major processes, including the acceleration, compression and ejection of plasmas, were modeled. By comparing the theoretical simulations with the experimental results, the acceleration mechanism was clarified. Moreover, through a series of experiments, the optimum operation range was investigated, and the acceleration ability was primarily determined.

  16. Exact Energy and Momentum Conservation in Variational Macro-Particle Plasma Models

    Science.gov (United States)

    Shadwick, B. A.; Evstatiev, E. G.; Nguyen, Nam

    2016-10-01

    We consider a class of variational macro-particle plasma models that exhibit simultaneous conservation of energy and momentum. These models retain translation invariance by using a Fourier representation of the electromagnetic fields in place of a spatial grid. That is, the Fourier amplitudes of the fields are the fundamental quantities. From the discrete Lagrangian, a canonical Hamiltonian system is obtained in the usual way, for which we introduce a symplectic integrator. We present a general formulation of the method with examples drawn from 1-1/2D studies of intense laser-plasma interactions. We comment on the relative merits of the Lagrangian vs. Hamiltonian formulations and discuss efficiency and practicality of using this technique in three dimensions. Supported by the National Science Foundation under Contract No. PHY-1104683.

  17. On the ordinary mode Weibel instability in space plasmas: A comparison of three-particle distributions

    Science.gov (United States)

    Rubab, Nazish; Chian, Abraham C.-L.; Jatenco-Pereira, Vera

    2016-03-01

    Electromagnetic wave fluctuations driven by temperature anisotropy in plasmas are of interest for solar flare, solar corona, and solar wind studies. We investigate the dispersion characteristics of electromagnetic wave propagating perpendicular to the uniform magnetic field which is derived by using multiple particle distribution functions: Maxwellian, bi-kappa, and product bi-kappa. The presence of temperature anisotropy in which the parallel plasma kinetic energy density exceeding by a sufficient amount can lead to Weibel-like electromagnetic instability. A general description is made to calculate the growth/damping rates of Weibel-like modes when the temperature anisotropy and nonthermal features are associated with these distributions. We demonstrate that for the zeroth cyclotron harmonic, our results for bi-Maxwellian and bi-kappa overlap with each other, while the product bi-kappa distribution shows some dependence on parallel kappa index. For higher harmonics, the growth rates vanish and the damping prevails.

  18. In situ analysis of size distribution of nano-particles in reactive plasmas using two dimensional laser light scattering method

    Science.gov (United States)

    Kamataki, K.; Morita, Y.; Shiratani, M.; Koga, K.; Uchida, G.; Itagaki, N.

    2012-04-01

    We have developed a simple in-situ method for measuring the size distribution (the mean size (mean diameter) and size dispersion) of nano-particles generated in reactive plasmas using the 2 dimensional laser light scattering (2DLLS) method. The principle of the method is based on thermal coagulation of the nano-particles, which occurs after the discharge is turned off, and the size and density of the nano-particles can then be deduced. We first determined the 2D spatial distribution of the density and size of the nano-particles in smaller particle size (a few nm) range than ones deduced from the conventional 2DLLS method. From this 2D dataset, we have for the first time been able to determine the size distribution of nano-particles generated in a reactive plasma without ex-situ measurements.

  19. Experimental Study of the Movement of Particles in the Coupled Field of Low Temperature Plasma and Cyclone

    Institute of Scientific and Technical Information of China (English)

    Ma Chaochen; Li Minghua; Wei Mingshan

    2005-01-01

    An investigation was made of the movement of particles in the coupled field of alow temperature plasma and cyclone with PIV in order to study the moving trace of particles'movement in an electrostatic cyclonic collector. The experimental results show that the plasmafield had little effect on the tangential velocity of particles, but had an obvious influence on theradial velocity. The tangential velocity of airflow had a great impact on particles' tangentialmovement. With the particles going down the cyclone tube, their tangential velocity dropped.Their radial velocity dropped as the radius enlarged from the center to the collecting wall of thetube. The plasma field could improve the radial velocity of particles by 5% ~ 10%, but the motionalong the radius was determined by the cyclone.

  20. HIV-1 Vpu promotes release and prevents endocytosis of nascent retrovirus particles from the plasma membrane.

    Directory of Open Access Journals (Sweden)

    2006-05-01

    Full Text Available The human immunodeficiency virus (HIV type-1 viral protein U (Vpu protein enhances the release of diverse retroviruses from human, but not monkey, cells and is thought to do so by ablating a dominant restriction to particle release. Here, we determined how Vpu expression affects the subcellular distribution of HIV-1 and murine leukemia virus (MLV Gag proteins in human cells where Vpu is, or is not, required for efficient particle release. In HeLa cells, where Vpu enhances HIV-1 and MLV release approximately 10-fold, concentrations of HIV-1 Gag and MLV Gag fused to cyan fluorescent protein (CFP were initially detected at the plasma membrane, but then accumulated over time in early and late endosomes. Endosomal accumulation of Gag-CFP was prevented by Vpu expression and, importantly, inhibition of plasma membrane to early endosome transport by dominant negative mutants of Rab5a, dynamin, and EPS-15. Additionally, accumulation of both HIV and MLV Gag in endosomes required a functional late-budding domain. In human HOS cells, where HIV-1 and MLV release was efficient even in the absence of Vpu, Gag proteins were localized predominantly at the plasma membrane, irrespective of Vpu expression or manipulation of endocytic transport. While these data indicated that Vpu inhibits nascent virion endocytosis, Vpu did not affect transferrin endocytosis. Moreover, inhibition of endocytosis did not restore Vpu-defective HIV-1 release in HeLa cells, but instead resulted in accumulation of mature virions that could be released from the cell surface by protease treatment. Thus, these findings suggest that a specific activity that is present in HeLa cells, but not in HOS cells, and is counteracted by Vpu, traps assembled retrovirus particles at the cell surface. This entrapment leads to subsequent endocytosis by a Rab5a- and clathrin-dependent mechanism and intracellular sequestration of virions in endosomes.

  1. A unified Monte Carlo interpretation of particle simulations and applications to nonneutral plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Aydemir, A.Y.

    1993-09-01

    Using a ``Monte Carlo interpretation`` a particle simulations, a general description of low-noise techniques is developed in terms well-known Monte Carlo variance reduction methods. Some of these techniques then are applied to linear and nonlinear studies of pure electron plasmas in cylindrical geometry, with emphasis on the generation and nonlinear evolution of electron vortices. Long-lived l = 1 and l and l = 2 vortices, and others produced by unstable diocotron modes in hollow profiles, are studies. It is shown that low-noise techniques make it possible to follow the linear evolution and saturation of even the very weakly unstable resonant diocotron modes.

  2. The Fluid-Kinetic Particle-in-Cell Solver for Plasma Simulations

    CERN Document Server

    Markidis, Stefano; Lapenta, Giovanni; Ronnmark, Kjell; Hamrin, Maria; Meliani, Zakaria; Laure, Erwin

    2013-01-01

    A new method that solves concurrently the multi-fluid and Maxwell's equations has been developed for plasma simulations. By calculating the stress tensor in the multi-fluid momentum equation by means of computational particles moving in a self-consistent electromagnetic field, the kinetic effects are retained while solving the multi-fluid equations. The Maxwell's and multi-fluid equations are discretized implicitly in time enabling kinetic simulations over time scales typical of the fluid simulations. The fluid-kinetic Particle-in-Cell solver has been implemented in a three-dimensional electromagnetic code, and tested against the ion cyclotron resonance and magnetic reconnection problems. The new method is a promising approach for coupling fluid and kinetic methods in a unified framework.

  3. Dust acoustic solitary structures in a multi-fluid dusty plasma in the presence of kappa distributed particles

    Science.gov (United States)

    Singh, Manpreet; Singh Saini, Nareshpal; Ghai, Yashika; Kaur, Nimardeep

    2016-07-01

    Dusty plasma is a fully or partially ionized gas which contain micron or sub-micron sized dust particles. These dust particles can be positively or negatively charged, depending upon the mechanism of charging . Dusty plasma is often observed in most of the space and astrophysical plasma environments. Presence of these dust particles can modify the dispersion properties of waves in the plasma and can introduce several new wave modes, e.g., dust acoustic (DA) waves, dust-ion acoustic (DIA) waves, dust-acoustic shock waves etc. In this investigation we have studied the small amplitude dust acoustic waves in an unmagnetized plasma comprising of electrons, positively charged ions, negatively charged hot as well as cold dust. Electrons and ions are described by superthermal distribution which is more appropriate for modeling space and astrophysical plasmas. Kadomtsev- Petviashvili (KP) equation has been derived using reductive perturbation technique. Positive as well as negative potential structures are observed, depending upon some critical values of parameters. Amplitude and width of dust acoustic solitary waves are modified by varying these parameters such as superthermality of electrons and ions, direction of propagation of the wave, relative concentration of hot and cold dust particles etc. This study may be helpful in understanding the formation and dynamics of nonlinear structures in various space and astrophysical plasma environments such Saturn's F-rings.

  4. Fully implicit Particle-in-cell algorithms for multiscale plasma simulation

    Energy Technology Data Exchange (ETDEWEB)

    Chacon, Luis [Los Alamos National Laboratory

    2015-07-16

    The outline of the paper is as follows: Particle-in-cell (PIC) methods for fully ionized collisionless plasmas, explicit vs. implicit PIC, 1D ES implicit PIC (charge and energy conservation, moment-based acceleration), and generalization to Multi-D EM PIC: Vlasov-Darwin model (review and motivation for Darwin model, conservation properties (energy, charge, and canonical momenta), and numerical benchmarks). The author demonstrates a fully implicit, fully nonlinear, multidimensional PIC formulation that features exact local charge conservation (via a novel particle mover strategy), exact global energy conservation (no particle self-heating or self-cooling), adaptive particle orbit integrator to control errors in momentum conservation, and canonical momenta (EM-PIC only, reduced dimensionality). The approach is free of numerical instabilities: ωpeΔt >> 1, and Δx >> λD. It requires many fewer dofs (vs. explicit PIC) for comparable accuracy in challenging problems. Significant CPU gains (vs explicit PIC) have been demonstrated. The method has much potential for efficiency gains vs. explicit in long-time-scale applications. Moment-based acceleration is effective in minimizing NFE, leading to an optimal algorithm.

  5. Particle Size and Pore Structure Characterization of Silver Nanoparticles Prepared by Confined Arc Plasma

    Directory of Open Access Journals (Sweden)

    Mingru Zhou

    2009-01-01

    Full Text Available In the protecting inert gas, silver nanoparticles were successfully prepared by confined arc plasma method. The particle size, microstructure, and morphology of the particles by this process were characterized via X-ray powder diffraction (XRD, transmission electron microscopy (TEM and the corresponding selected area electron diffraction (SAED. The N2 absorption-desorption isotherms of the samples were measured by using the static volumetric absorption analyzer, the pore structure of the sample was calculated by Barrett-Joyner-Halenda (BJH academic model, and the specific surface area was calculated from Brunauer-Emmett-Teller (BET adsorption equation. The experiment results indicate that the crystal structure of the samples is face-centered cubic (FCC structure the same as the bulk materials, the particle size distribution ranging from 5 to 65 nm, with an average particle size about 26 nm obtained by TEM and confirmed by XRD and BET results. The specific surface area is 23.81 m2/g, pore volumes are 0.09 cm3/g, and average pore diameter is 18.7 nm.

  6. ELM simulation experiments using transient heat and particle load produced by a magnetized coaxial plasma gun

    Science.gov (United States)

    Shoda, K.; Sakuma, I.; Iwamoto, D.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2011-10-01

    It is considered that thermal transient events such as type I edge-localized modes (ELMs) and disruptions will limit the lifetime of plasma-facing components (PFCs) in ITER. It is predicted that the heat load onto the PFCs during type I ELMs in ITER is 0.2-2MJ/m2 with pulse length of ~0.1-1ms. We have investigated interaction between transient heat and particle load and the PFCs by using a magnetized coaxial plasma gun (MCPG) at University of Hyogo. In the experiment, a pulsed plasma with duration of ~0.5ms, incident ion energy of ~30eV, and surface absorbed energy density of ~0.3-0.7MJ/m2 was produced by the MCPG. However, no melting occurred on a tungsten surface exposed to a single plasma pulse of ~0.7MJ/m2, while cracks clearly appeared at the edge part of the W surface. Thus, we have recently started to improve the performance of the MCPG in order to investigate melt layer dynamics of a tungsten surface such as vapor cloud formation. In the modified MCPG, the capacitor bank energy for the plasma discharge is increased from 24.5 kJ to 144 kJ. In the preliminary experiments, the plasmoid with duration of ~0.6 ms, incident ion energy of ~ 40 eV, and the surface absorbed energy density of ~2 MJ/m2 was successfully produced at the gun voltage of 6 kV.

  7. Modelling and analysis of particles transport in a tokamak plasma; Modelisation et analyse du transport des particules dans un plasma de Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Laporte Patrice, M.

    1996-02-22

    The results developed in this thesis describe the ions and neutral atoms transport in a tokamak plasma. The effort is especially made on modelling of neutral particles transport. The presentation of the two computer codes Trap and Neli take the first part of the thesis. This study shows that heat and matter transport anomaly present some real characteristics of an electrostatic turbulence. Then, if particles diffusivity stays abnormal on the whole discharge of a tore supra plasma, in revenge in the central part of the discharge, the convective flux value is compatible with neoclassical theory. (N.C.). 67 refs., 67 figs., 6 appends.

  8. The diffusion of charged particles in the weakly ionized plasma with power-law kappa-distributions

    Science.gov (United States)

    Wang, Lan; Du, Jiulin

    2017-10-01

    We study the diffusion of charged particles in the weakly ionized plasma with the power-law κ-distributions and without the magnetic field. The electrons and ions have different κ-parameters. We obtain the expressions of both diffusion and mobility coefficients of electrons and ions respectively in the plasma. We find that these new transport coefficient formulae depend strongly on the κ-parameters in the power-law distributed plasma. When we take κ→∞, these formulae reduce to the classical forms in the weakly ionized plasma with a Maxwellian distribution.

  9. Effects of Plasma Nitriding on the Erosion Behavior of AISI 403 Stainless Steel Solid State Particles

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Ji Won; Park, Hee Jin; Baik, Kyeong Ho [Chungnam National University, Daejeon (Korea, Republic of); Kim, In Soo; Yang, Byung Il [Doosan Heavy Industries and Construction Co., Ltd., Changwon (Korea, Republic of)

    2014-01-15

    This study investigated the effects of plasma nitriding on the erosion behavior of AISI 403 stainless steel solid state particles at ambient temperature and 620 ℃ using Fe{sub 3}O{sub 4} erodent particles at impact angles of 15-90°. The plasma nitriding formed a thick hardened layer which had a high microhardness of 1210 ± 15 Hv. At ambient temperature, AISI 403 suffered from severe erosion damage at low impact angles and exhibited ductile erosive behavior, while the nitrided layer experienced no significant damage at any impact angles. For AISI 403, the erosion rates at 620 ℃ were ⁓2 times higher than those obtained at ambient temperature. When eroded at 620 ℃, the nitrided layer exhibited a ductile erosive manner, with a maximum erosion rate occurring at a low impact angle of 30°. The results from high temperature hardness measurement and the observation of the eroded surface are discussed to explain the high-temperature erosion behavior of the nitrided AISI 403 stainless steel.

  10. Plasma brominated polymer particles as grafting substrate for thiol-terminated telomers.

    Science.gov (United States)

    Byström, Emil; Nordborg, Anna; Limé, Fredrik; Dinh, Ngoc Phuoc; Irgum, Knut

    2010-06-01

    A combined surface activation and "grafting to" strategy was developed to convert divinylbenzene particles into weak cation exchangers suitable for protein separation. The initial activation step was based on plasma modification with bromoform, which rendered the particles amenable to further reaction with nucleophiles by introducing Br to a surface content of 11.2 atom-%, as determined by X-ray photoelectron spectroscopy. Grafting of thiol-terminated glydicyl methacrylate telomers to freshly plasma activated surfaces was accomplished without the use of added initiator, and the grafting was verified both by reduction in bromine content and the appearance of sulfur-carbon linkages, showing that the surface grafts were covalently bonded. Following grafting the attached glydicyl methacrylate telomer tentacles were further modified by a two-step procedure involving hydrolysis to 2,3-hydroxypropyl groups and conversion of hydroxyl groups to carboxylate functionality by succinic anhydride. The final material was capable of baseline separating four model proteins in 3 min by gradient cation exchange chromatography in a fully aqueous eluent.

  11. Electromagnetic ion-cyclotron instability in a dusty plasma with product-bi-kappa distributions for the plasma particles

    Science.gov (United States)

    dos Santos, M. S.; Ziebell, L. F.; Gaelzer, R.

    2017-01-01

    We study the dispersion relation for parallel propagating ion-cyclotron (IC) waves in a dusty plasma, considering situations where the velocity dispersion along perpendicular direction is greater than along the parallel direction, and considering the use of product-bi-kappa (PBK) velocity distributions for the plasma particles. The results obtained by numerical solution of the dispersion relation, in a case with isotropic Maxwellian distributions for electrons and PBK distribution for ions, show the occurrence of the electromagnetic ion-cyclotron instability (EMIC), and show that the decrease in the kappa indexes of the PBK ion distribution leads to significant increase in the magnitude of the growth rates and in the range of wavenumber for which the instability occurs. On the other hand, for anisotropic Maxwellian distribution for ions and PBK distribution for electrons, the decrease of the kappa index in the PBK electron distribution contributes to reduce the growth rate of the EMIC instability, but the reduction effect is less pronounced than the increase obtained with ion PBK distribution with the same kappa index. The results obtained also show that, as a general rule, the presence of a dust population contributes to reduce the instability in magnitude of the growth rates and range, but that in the case of PBK ion distribution with small kappa indexes the instability may continue to occur for dust populations which would eliminate completely the instability in the case of bi-Maxwellian ion distributions. It has also been seen that the anisotropy due to the kappa indexes in the ion PBK distribution is not so efficient in producing the EMIC instability as the ratio of perpendicular and parallel ion temperatures, for equivalent value of the effective temperature.

  12. Acute effects of inhaled urban particles and ozone: lung morphology, macrophage activity, and plasma endothelin-1.

    Science.gov (United States)

    Bouthillier, L; Vincent, R; Goegan, P; Adamson, I Y; Bjarnason, S; Stewart, M; Guénette, J; Potvin, M; Kumarathasan, P

    1998-12-01

    We studied acute responses of rat lungs to inhalation of urban particulate matter and ozone. Exposure to particles (40 mg/m3 for 4 hours; mass median aerodynamic diameter, 4 to 5 microm; Ottawa urban dust, EHC-93), followed by 20 hours in clean air, did not result in acute lung injury. Nevertheless, inhalation of particles resulted in decreased production of nitric oxide (nitrite) and elevated secretion of macrophage inflammatory protein-2 from lung lavage cells. Inhalation of ozone (0.8 parts per million for 4 hours) resulted in increased neutrophils and protein in lung lavage fluid. Ozone alone also decreased phagocytosis and nitric oxide production and stimulated endothelin-1 secretion by lung lavage cells but did not modify secretion of macrophage inflammatory protein-2. Co-exposure to particles potentiated the ozone-induced septal cellularity in the central acinus but without measurable exacerbation of the ozone-related alveolar neutrophilia and permeability to protein detected by lung lavage. The enhanced septal thickening was associated with elevated production of both macrophage inflammatory protein-2 and endothelin-1 by lung lavage cells. Interestingly, inhalation of urban particulate matter increased the plasma levels of endothelin-1, but this response was not influenced by the synergistic effects of ozone and particles on centriacinar septal tissue changes. This suggests an impact of the distally distributed particulate dose on capillary endothelial production or filtration of the vasoconstrictor. Overall, equivalent patterns of effects were observed after a single exposure or three consecutive daily exposures to the pollutants. The experimental data are consistent with epidemiological evidence for acute pulmonary effects of ozone and respirable particulate matter and suggest a possible mechanism whereby cardiovascular effects may be induced by particle exposure. In a broad sense, acute biological effects of respirable particulate matter from ambient air

  13. Particle-in-Cell Modeling of Magnetized Argon Plasma Flow Through Small Mechanical Apertures

    Energy Technology Data Exchange (ETDEWEB)

    Adam B. Sefkow and Samuel A. Cohen

    2009-04-09

    Motivated by observations of supersonic argon-ion flow generated by linear helicon-heated plasma devices, a three-dimensional particle-in-cell (PIC) code is used to study whether stationary electrostatic layers form near mechanical apertures intersecting the flow of magnetized plasma. By self-consistently evaluating the temporal evolution of the plasma in the vicinity of the aperture, the PIC simulations characterize the roles of the imposed aperture and applied magnetic field on ion acceleration. The PIC model includes ionization of a background neutral-argon population by thermal and superthermal electrons, the latter found upstream of the aperture. Near the aperture, a transition from a collisional to a collisionless regime occurs. Perturbations of density and potential, with mm wavelengths and consistent with ion acoustic waves, propagate axially. An ion acceleration region of length ~ 200-300 λD,e forms at the location of the aperture and is found to be an electrostatic double layer, with axially-separated regions of net positive and negative charge. Reducing the aperture diameter or increasing its length increases the double layer strength.

  14. Charged particle dynamics and molecular kinetics in the hydrogen postdischarge plasma

    Science.gov (United States)

    Diomede, P.; Longo, S.; Capitelli, M.

    2006-11-01

    The afterglow of a parallel plate radio frequency discharge in hydrogen is studied by numerical modelling to compare ion dynamics and chemical effects on the behavior of negative ions. While the ion dynamics requires a kinetic description of space dependent plasma relaxation (at least 1D), chemical effects require a vibrational kinetics of hydrogen molecules. Since previous models did not include both features it has not been possible until now to realize both effects in a single simulation. We apply an updated version of the 1D Bari model which includes a 1.5D (1Dr2Dv) Particle in Cell/Monte Carlo (PIC/MC) multispecies module coupled to the space and time dependent master equation for H2(X1Σg+,v=0,…,14) vibrational level population. Negative ion fronts are described in hydrogen for the first time and their impact on the plasma limiting surfaces produces a negative ion current evolution compatible with experimental findings. In the same conditions, the attachment rate overshoot is found to contribute about 7% to the average ion density in the plasma.

  15. Particle-In-Cell Simulation on the Characteristics of a Receiving Antenna in Space Plasma Environment

    Science.gov (United States)

    Miyake, Yohei; Usui, Hideyuki; Kojima, Hirotsugu; Omura, Yoshiharu

    2008-12-01

    We applied the electromagnetic Particle-In-Cell simulation to the analysis of receiving antenna characteristics in space plasma environment. In the analysis, we set up external waves in a simulation region and receive them with a numerical antenna model placed in the simulation region. Using this method, we evaluated the effective length of electric field antennas used for plasma wave investigations conducted by scientific spacecraft. We particularly focused on the effective length of an electric field instrument called MEFISTO for a future mission to Mercury: BepiColombo. We first confirmed that the effective length of the MEFISTO-type antenna is basically longer than that of a simple dipole antenna for both electrostatic and electromagnetic plasma waves. By applying the principle of a voltmeter, the effective length of the MEFISTO-type antenna is predicted to become identical to the separation between two sensor-conductor's midpoints. However, the numerical result revealed that the actual effective length becomes shorter than the prediction, which is caused by the shorting-out effect due to the presence of a center boom conductor between the two sensor conductors. Since the above effect is difficult to treat theoretically, the present numerical method is a powerful tool for further quantitative evaluation of the antenna characteristics.

  16. On energy and momentum conservation in particle-in-cell plasma simulation

    Science.gov (United States)

    Brackbill, J. U.

    2016-07-01

    Particle-in-cell (PIC) plasma simulations are a productive and valued tool for the study of nonlinear plasma phenomena, yet there are basic questions about the simulation methods themselves that remain unanswered. Here we study energy and momentum conservation by PIC. We employ both analysis and simulations of one-dimensional, electrostatic plasmas to understand why PIC simulations are either energy or momentum conserving but not both, what role a numerical stability plays in non-conservation, and how errors in conservation scale with the numerical parameters. Conserving both momentum and energy make it possible to model problems such as Jeans'-type equilibria. Avoiding numerical instability is useful, but so is being able to identify when its effect on the results may be important. Designing simulations to achieve the best possible accuracy with the least expenditure of effort requires results on the scaling of error with the numerical parameters. Our results identify the central role of Gauss' law in conservation of both momentum and energy, and the significant differences in numerical stability and error scaling between energy-conserving and momentum-conserving simulations.

  17. Particle Heating and Energization During Magnetic Reconnection Events in MST Plasmas

    Science.gov (United States)

    Dubois, Ami M.; Almagri, A. F.; Anderson, J. K.; den Hartog, D. J.; Forest, C.; Nornberg, M.; Sarff, J. S.

    2015-11-01

    Magnetic reconnection plays an important role in particle transport, energization, and acceleration in space, astrophysical, and laboratory plasmas. In MST reversed field pinch plasmas, discrete magnetic reconnection events release large amounts of energy from the equilibrium magnetic field, resulting in non-collisional ion heating. However, Thomson Scattering measures a decrease in the thermal electron temperature. Recent fast x-ray measurements show an enhancement in the high energy x-ray flux during reconnection, where the coupling between edge and core tearing modes is essential for enhanced flux. A non-Maxwellian energetic electron tail is generated during reconnection, where the power law spectral index (γ) decreases from 4.3 to 1.8 and is dependent on density, plasma current, and the reversal parameter. After the reconnection event, γ increases rapidly to 5.8, consistent with the loss of energetic electrons due to stochastic thermal transport. During the reconnection event, the change in γ is correlated with the change in magnetic energy stored in the equilibrium field, indicating that the released magnetic energy may be an energy source for electron energization. Recent experimental and computational results of energetic electron tail formation during magnetic reconnection events will be presented. This work is supported by the U.S. DOE and the NSF.

  18. Construction of an Alpha Particle Spark Detector and Fusor for research in plasma physics and radiation detection

    Science.gov (United States)

    Akinsulire, Olorunsola; Fils-Aime, Fabrice; Hecla, Jake; Short, Michael; White, Anne

    2016-10-01

    This project delves into the realms of plasma physics and nuclear engineering by exploring systems used to generate plasmas and detect radiation. Basic plasma processes can be explored using inertial electrostatic confinement, in a device commonly called a ``fusor''. The fusor will generate neutrons and x-rays. The breakdown of air within a spark gap can be achieved with alpha particles and the avalanche effect; and constitutes an Alpha Particle Spark Detector (APSD), relevant for studies of basic nuclear processes and detectors. In the fusor, preliminary data was collected on breakdown voltage versus pressure in an air plasma to see how well the current system and geometry match up with expectations for the Paschen curve. A stable plasma was observed, at voltages roughly consistent with expectations, and it was concluded that a more controlled gas introduction system is needed to maintain a steady plasma over wider pressure ranges, and will allow for introduction of D2 gas for the study of neutron and x-ray producing plasmas. This poster will discuss the design, construction, and initial operation of the Alpha Particle Spark Detector and the fusor as part of an Undergraduate Research Opportunity (UROP) project. MIT UROP Program and the NSE department.

  19. Analytical estimation of particle shape formation parameters in a plasma-chemical reactor

    Directory of Open Access Journals (Sweden)

    Zhukov Ilya A.

    2017-01-01

    Full Text Available Analytical estimation of particle shape formation parameters in a plasma-chemical reactor implementing the process of thermochemical decomposition of liquid droplet agents (precursors in the flow of a high-temperature gaseous heat-transfer medium was obtained. The basic factor which determines the process is the increase of concentration of a dissolved salt precursor component at the surface of a liquid particle due to solvent evaporation. According to the physical concept of the method of integral balance the diffusion process of concentration change is divided into two stages: the first stage is when the size of gradient layer does not reach the center of a spherical droplet and the second stage when the concentration at the center of a liquid droplet begins to change. The solutions for concentration fields were found for each stage using the method of integral balance taking into account the formation of salt precipitate when the concentration at the surface of the droplet reaches certain equilibrium value. The results of estimation of the influence of various reactor operation parameters and characteristics of initial solution (precursor on the morphology of particles formed – mass fraction and localization of salt precipitate for various levels of evaporation.

  20. Energetic Particle Physics In Fusion Research In Preparation For Burning Plasma Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Gorelenkov, Nikolai N [PPPL

    2013-06-01

    The area of energetic particle (EP) physics of fusion research has been actively and extensively researched in recent decades. The progress achieved in advancing and understanding EP physics has been substantial since the last comprehensive review on this topic by W.W. Heidbrink and G.J. Sadler [1]. That review coincided with the start of deuterium-tritium (DT) experiments on Tokamak Fusion Test reactor (TFTR) and full scale fusion alphas physics studies. Fusion research in recent years has been influenced by EP physics in many ways including the limitations imposed by the "sea" of Alfven eigenmodes (AE) in particular by the toroidicityinduced AEs (TAE) modes and reversed shear Alfven (RSAE). In present paper we attempt a broad review of EP physics progress in tokamaks and spherical tori since the first DT experiments on TFTR and JET (Joint European Torus) including helical/stellarator devices. Introductory discussions on basic ingredients of EP physics, i.e. particle orbits in STs, fundamental diagnostic techniques of EPs and instabilities, wave particle resonances and others are given to help understanding the advanced topics of EP physics. At the end we cover important and interesting physics issues toward the burning plasma experiments such as ITER (International Thermonuclear Experimental Reactor).

  1. Inertially confined fusion plasmas dominated by alpha-particle self-heating

    Science.gov (United States)

    Hurricane, O. A.; Callahan, D. A.; Casey, D. T.; Dewald, E. L.; Dittrich, T. R.; Döppner, T.; Haan, S.; Hinkel, D. E.; Berzak Hopkins, L. F.; Jones, O.; Kritcher, A. L.; Le Pape, S.; Ma, T.; Macphee, A. G.; Milovich, J. L.; Moody, J.; Pak, A.; Park, H.-S.; Patel, P. K.; Ralph, J. E.; Robey, H. F.; Ross, J. S.; Salmonson, J. D.; Spears, B. K.; Springer, P. T.; Tommasini, R.; Albert, F.; Benedetti, L. R.; Bionta, R.; Bond, E.; Bradley, D. K.; Caggiano, J.; Celliers, P. M.; Cerjan, C.; Church, J. A.; Dylla-Spears, R.; Edgell, D.; Edwards, M. J.; Fittinghoff, D.; Barrios Garcia, M. A.; Hamza, A.; Hatarik, R.; Herrmann, H.; Hohenberger, M.; Hoover, D.; Kline, J. L.; Kyrala, G.; Kozioziemski, B.; Grim, G.; Field, J. E.; Frenje, J.; Izumi, N.; Gatu Johnson, M.; Khan, S. F.; Knauer, J.; Kohut, T.; Landen, O.; Merrill, F.; Michel, P.; Moore, A.; Nagel, S. R.; Nikroo, A.; Parham, T.; Rygg, R. R.; Sayre, D.; Schneider, M.; Shaughnessy, D.; Strozzi, D.; Town, R. P. J.; Turnbull, D.; Volegov, P.; Wan, A.; Widmann, K.; Wilde, C.; Yeamans, C.

    2016-08-01

    Alpha-particle self-heating, the process of deuterium-tritium fusion reaction products depositing their kinetic energy locally within a fusion reaction region and thus increasing the temperature in the reacting region, is essential for achieving ignition in a fusion system. Here, we report new inertial confinement fusion experiments where the alpha-particle heating of the plasma is dominant with the fusion yield produced exceeding the fusion yield from the work done on the fuel (pressure times volume change) by a factor of two or more. These experiments have achieved the highest yield (26 +/- 0.5 kJ) and stagnation pressures (≍220 +/- 40 Gbar) of any facility-based inertial confinement fusion experiments, although they are still short of the pressures required for ignition on the National Ignition Facility (~300-400 Gbar). These experiments put us in a new part of parameter space that has not been extensively studied so far because it lies between the no-alpha-particle-deposition regime and ignition.

  2. Proton-driven plasma wakefield acceleration: a path to the future of high-energy particle physics

    CERN Document Server

    Assmann, R; Bohl, T; Bracco, C; Buttenschön, B; Butterworth, A; Caldwell, A; Chattopadhyay, S; Cipiccia, S; Feldbaumer, E; Fonseca, R A; Goddard, B; Gross, M; Grulke, O; Gschwendtner, E; Holloway, J; Huang, C; Jaroszynski, D; Jolly, S; Kempkes, P; Lopes, N; Lotov, K; Machacek, J; Mandry, S R; McKenzie, J W; Meddahi, M; Militsyn, B L; Moschuering, N; Muggli, P; Najmudin, Z; Noakes, T C Q; Norreys, P A; Öz, E; Pardons, A; Petrenko, A; Pukhov, A; Rieger, K; Reimann, O; Ruhl, H; Shaposhnikova, E; Silva, L O; Sosedkin, A; Tarkeshian, R; Trines, R M G N; Tückmantel, T; Vieira, J; Vincke, H; Wing, M; Xia G , G

    2014-01-01

    New acceleration technology is mandatory for the future elucidation of fundamental particles and their interactions. A promising approach is to exploit the properties of plasmas. Past research has focused on creating large-amplitude plasma waves by injecting an intense laser pulse or an electron bunch into the plasma. However, the maximum energy gain of electrons accelerated in a single plasma stage is limited by the energy of the driver. Proton bunches are the most promising drivers of wakefields to accelerate electrons to the TeV energy scale in a single stage. An experimental program at CERN { the AWAKE experiment { has been launched to study in detail the important physical processes and to demonstrate the power of proton-driven plasma wakefield acceleration. Here we review the physical principles and some experimental considerations for a future proton-driven plasma wakefield accelerator.

  3. Proton-driven plasma wakefield acceleration: a path to the future of high-energy particle physics

    CERN Document Server

    Assmann, R; Bohl, T; Bracco, C; Buttenschon, B; Butterworth, A; Caldwell, A; Chattopadhyay, S; Cipiccia, S; Feldbaumer, E; Fonseca, R A; Goddard, B; Gross, M; Grulke, O; Gschwendtner, E; Holloway, J; Huang, C; Jaroszynski, D; Jolly, S; Kempkes, P; Lopes, N; Lotov, K; Machacek, J; Mandry, S R; McKenzie, J W; Meddahi, M; Militsyn, B L; Moschuering, N; Muggli, P; Najmudin, Z; Noakes, T C Q; Norreys, P A; Oz, E; Pardons, A; Petrenko, A; Pukhov, A; Rieger, K; Reimann, O; Ruhl, H; Shaposhnikova, E; Silva, L O; Sosedkin, A; Tarkeshian, R; Trines, R M G N; Tuckmantel, T; Vieira, J; Vincke, H; Wing, M; Xia, G

    2014-01-01

    New acceleration technology is mandatory for the future elucidation of fundamental particles and their interactions. A promising approach is to exploit the properties of plasmas. Past research has focused on creating large-amplitude plasma waves by injecting an intense laser pulse or an electron bunch into the plasma. However, the maximum energy gain of electrons accelerated in a single plasma stage is limited by the energy of the driver. Proton bunches are the most promising drivers of wakefields to accelerate electrons to the TeV energy scale in a single stage. An experimental program at CERN -- the AWAKE experiment -- has been launched to study in detail the important physical processes and to demonstrate the power of proton-driven plasma wakefield acceleration. Here we review the physical principles and some experimental considerations for a future proton-driven plasma wakefield accelerator.

  4. Particle-in-cell simulations of the relaxation of electron beams in inhomogeneous solar wind plasmas

    Science.gov (United States)

    Thurgood, Jonathan O.; Tsiklauri, David

    2016-12-01

    Previous theoretical considerations of electron beam relaxation in inhomogeneous plasmas have indicated that the effects of the irregular solar wind may account for the poor agreement of homogeneous modelling with the observations. Quasi-linear theory and Hamiltonian models based on Zakharov's equations have indicated that when the level of density fluctuations is above a given threshold, density irregularities act to de-resonate the beam-plasma interaction, restricting Langmuir wave growth on the expense of beam energy. This work presents the first fully kinetic particle-in-cell (PIC) simulations of beam relaxation under the influence of density irregularities. We aim to independently determine the influence of background inhomogeneity on the beam-plasma system, and to test theoretical predictions and alternative models using a fully kinetic treatment. We carry out one-dimensional (1-D) PIC simulations of a bump-on-tail unstable electron beam in the presence of increasing levels of background inhomogeneity using the fully electromagnetic, relativistic EPOCH PIC code. We find that in the case of homogeneous background plasma density, Langmuir wave packets are generated at the resonant condition and then quasi-linear relaxation leads to a dynamic increase of wavenumbers generated. No electron acceleration is seen - unlike in the inhomogeneous experiments, all of which produce high-energy electrons. For the inhomogeneous experiments we also observe the generation of backwards-propagating Langmuir waves, which is shown directly to be due to the refraction of the packets off the density gradients. In the case of higher-amplitude density fluctuations, similar features to the weaker cases are found, but also packets can also deviate from the expected dispersion curve in -space due to nonlinearity. Our fully kinetic PIC simulations broadly confirm the findings of quasi-linear theory and the Hamiltonian model based on Zakharov's equations. Strong density fluctuations

  5. Comparative study between cold plasma and hot plasma with ion beam and loss-cone distribution function by particle aspect approach

    Science.gov (United States)

    Patel, Soniya; Varma, P.; Tiwari, M. S.

    2011-03-01

    The electromagnetic ion-cyclotron (EMIC) instabilities with isotropic ion beam and general loss-cone distribution of cold and hot core plasmas are discussed. The growth rate, parallel and perpendicular resonance energies of the electromagnetic ion-cyclotron waves in a low β (ratio of plasma pressure to magnetic pressure), homogeneous plasma have been obtained using the dispersion relation for cold and hot plasmas. The wave is assumed to propagate parallel to the static magnetic field. The whole plasma is considered to consist of resonant and non-resonant particles permeated by isotropic ion beam. It is assumed that resonant particles and ion beam participate in energy exchange with the wave whereas non-resonant particles support the oscillatory motion of the wave. We determined the variation in energies and growth rate in cold and hot plasmas by the energy conservation method with a general loss-cone distribution function. The thermal anisotropy of the core plasma acts as a source of free energy for EMIC wave and enhances the growth rate. It is noted that the EMIC wave emissions occur by extracting energy of perpendicularly heated ions in the presence of up flowing ion beam and steep loss-cone distribution in the anisotropic magnetosphere. The effect of the steep loss-cone distribution is to enhance the growth rate of the EMIC wave. The heating of ions perpendicular and parallel to the magnetic field is discussed along with EMIC wave emission in the auroral acceleration region. The results are interpreted for the space plasma parameters appropriate to the auroral acceleration region of the earth's magnetoplasma.

  6. Observational Evidence of Particle Acceleration Associated with Plasmoid Motions

    CERN Document Server

    Takasao, Shinsuke; Isobe, Hiroaki; Shibata, Kazunari

    2016-01-01

    We report a strong association between the particle acceleration and plasma motions found in the 2010 August 18 solar flare. The plasma motions are tracked in the extreme-ultraviolet (EUV) images taken by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory and the Extreme UltraViolet Imager (EUVI) on the Solar Terrestrial Relation Observatory spacecraft Ahead, and the signature of particle acceleration was investigated by using Nobeyama Radioheliograph data. In our previous paper, we reported that in EUV images many plasma blobs appeared in the current sheet above the flare arcade. They were ejected bidirectionally along the current sheet, and the blobs that were ejected sunward collided with the flare arcade. Some of them collided or merged with each other before they were ejected from the current sheet. We discovered impulsive radio bursts associated with such plasma motions (ejection, coalescence, and collision with the post flare loops). The radio bursts are considered to be the...

  7. Comparisons of particles thermal behavior between Fe-base alloy and boron carbide during plasma transferred-arc powder surfacing

    Institute of Scientific and Technical Information of China (English)

    王惜宝

    2003-01-01

    Comparisons of particle's thermal behavior between Fe-base alloy and boron carbide in plasma transferred-arc (PTA) space was made based on theoretical evaluation results in this article. It was found that most of the Fe base particles would be fully melted while they transporting through the central plasma field with 200 A surfacing currents. And the particles with a diameter less than 0.5×10-4 m might be fully evaporated. However, for the boron carbide (B4C) particles, only the one with a diameter less than 0.5×10-4 m could be melted in the same PTA space. Most of B4C particles are only preheated at its solid state when they were fed through the central field of PTA plasma when the surfacing current is equal to or less than 200 A. When the arc current was smaller than100 A, only the particles smaller than 0.5×10-4 m could be melted in the PTA space for the Fe-base alloy. Almost none of the discussed B4C particles could be melted in the 100 A PTA space.

  8. Stochastic heating of dust particles in complex plasmas as an energetic instability of a harmonic oscillator with random frequency

    Energy Technology Data Exchange (ETDEWEB)

    Marmolino, Ciro [Dipartimento di Scienze e Tecnologie dell' Ambiente e del Territorio-DiSTAT, Universita del Molise, Contrada Fonte Lappone, I-86090 Pesche (Italy)

    2011-10-15

    The paper describes the occurrence of stochastic heating of dust particles in dusty plasmas as an energy instability due to the correlations between dust grain charge and electric field fluctuations. The possibility that the mean energy (''temperature'') of dust particles can grow in time has been found both from the self-consistent kinetic description of dusty plasmas taking into account charge fluctuations [U. de Angelis, A. V. Ivlev, V. N. Tsytovich, and G. E. Morfill, Phys. Plasmas 12(5), 052301 (2005)] and from a Fokker-Planck approach to systems with variable charge [A. V. Ivlev, S. K. Zhdanov, B. A. Klumov, and G. E. Morfill, Phys. Plasmas 12(9), 092104 (2005)]. Here, a different derivation is given by using the mathematical techniques of the so called multiplicative stochastic differential equations. Both cases of ''fast'' and ''slow'' fluctuations are discussed.

  9. Levitation and collection of diamond fine particles in the rf plasma chamber equipped with a hot filament

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, S.; Shimizu, T.; Thomas, H. M.; Morfill, G. E. [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany); Jacob, W. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstrasse 2, D-85748 Garching (Germany)

    2011-11-15

    We demonstrate the levitation of diamond fine particles in a H{sub 2} rf plasma chamber equipped with a hot filament and heated electrodes. The levitation conditions should be carefully chosen to compensate the strong thermophoretic forces caused by the filament and the electrodes. This levitation technique with the existence of a hot filament can be applied, e.g., for the efficient growth of diamond layers on seed particles injected and levitated in an rf plasma with reactive gases, e.g., CH{sub 4}/H{sub 2}. Additionally, the method for direct capture of levitated particles on a planar substrate was established, which is useful if it is necessary to analyze the particles after the levitation.

  10. A Volume-Weighting Cloud-in-Cell Model for Particle Simulation of Axially Symmetric Plasmas

    Institute of Scientific and Technical Information of China (English)

    李永东; 何锋; 刘纯亮

    2005-01-01

    A volume-weighting cloud-in-cell (VW-CIC) model is developed to implement the particle-in-cell (PIC) simulation in axially symmetric systems. This model gives a first-order accuracy in the cylindrical system, and it is incorporated into a PIC code. A planar diode with a finite-radius circular emitter is simulated with the code. The simulation results show that the VW-CIC model has a better accuracy and a lower noise than the conventional area-weighting cloud-in-cell (AW-CIC) model, especially on those points near the axis. The two-dimensional (2-D) space-charge-limited current density obtained from VW-CIC model is in better agreement with Lau's analytical result. This model is more suitable for 2.5-D PIC simulation of axially symmetric plasmas.

  11. Accurate modeling of plasma acceleration with arbitrary order pseudo-spectral particle-in-cell methods

    Science.gov (United States)

    Jalas, S.; Dornmair, I.; Lehe, R.; Vincenti, H.; Vay, J.-L.; Kirchen, M.; Maier, A. R.

    2017-03-01

    Particle in Cell (PIC) simulations are a widely used tool for the investigation of both laser- and beam-driven plasma acceleration. It is a known issue that the beam quality can be artificially degraded by numerical Cherenkov radiation (NCR) resulting primarily from an incorrectly modeled dispersion relation. Pseudo-spectral solvers featuring infinite order stencils can strongly reduce NCR—or even suppress it—and are therefore well suited to correctly model the beam properties. For efficient parallelization of the PIC algorithm, however, localized solvers are inevitable. Arbitrary order pseudo-spectral methods provide this needed locality. Yet, these methods can again be prone to NCR. Here, we show that acceptably low solver orders are sufficient to correctly model the physics of interest, while allowing for parallel computation by domain decomposition.

  12. Accurate modeling of plasma acceleration with arbitrary order pseudo-spectral particle-in-cell methods

    CERN Document Server

    Jalas, Sören; Lehe, Rémi; Vincenti, Henri; Vay, Jean-Luc; Kirchen, Manuel; Maier, Andreas R

    2016-01-01

    Particle in Cell (PIC) simulations are a widely used tool for the investigation of both laser- and beam-driven plasma acceleration. It is a known issue that the beam quality can be artificially degraded by numerical Cherenkov radiation (NCR) resulting primarily from an incorrectly modeled dispersion relation. Pseudo-spectral solvers featuring infinite order stencils can strongly reduce NCR -- or even suppress it -- and are therefore well suited to correctly model the beam properties. For efficient parallelization of the PIC algorithm, however, localized solvers are inevitable. Arbitrary order pseudo-spectral methods provide this needed locality. Yet, these methods can again be prone to NCR. Here, we show that acceptably low solver orders are sufficient to correctly model the physics of interest, while allowing for efficient parallelization.

  13. Comparing Particle-in-Cell QED Models for High-Intensity Laser-Plasma Interactions

    Science.gov (United States)

    Luedtke, Scott V.; Labun, Lance A.; Hegelich, Björn Manuel

    2016-10-01

    High-intensity lasers, such as the Texas Petawatt, are pushing into new regimes of laser-matter interaction, requiring continuing improvement and inclusion of new physics effects in computer simulations. Experiments at the Texas Petawatt are reaching intensity regimes where new physics-quantum electrodynamics (QED) corrections to otherwise classical plasma dynamics-becomes important. We have two particle-in-cell (PIC) codes with different QED implementations. We review the theory of photon emission in QED-strong fields, and cover the differing PIC implementations. We show predictions from the two codes and compare with ongoing experiments. This work was supported by NNSA cooperative agreement DE-NA0002008, the Defense Advanced Research Projects Agency's PULSE program (12-63-PULSE-FP014) and the Air Force Office of Scientific Research (FA9550-14-1-0045). HPC resources provided by TACC.

  14. Multiplex DNA assay based on nanoparticle probes by single particle inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Zhang, Shixi; Han, Guojun; Xing, Zhi; Zhang, Sichun; Zhang, Xinrong

    2014-04-01

    A multiplex DNA assay based on nanoparticle (NP) tags detection utilizing single particle mode inductively coupled plasma mass spectrometry (SP-ICP-MS) as ultrasensitive readout has been demonstrated in the article. Three DNA targets associated with clinical diseases (HIV, HAV, and HBV) down to 1 pM were detected by DNA probes labeled with AuNPs, AgNPs, and PtNPs via DNA sandwich assay. Single nucleotide polymorphisms in genes can also be effectively discriminated. Since our method is unaffected by the sample matrix, it is well-suited for diagnostic applications. Moreover, with the high sensitivity of SP-ICP-MS and the variety of NPs detectable by SP-ICP-MS, high-throughput DNA assay could be achieved without signal amplification or chain reaction amplification.

  15. Convergence of statistical moments of particle density time series in scrape-off layer plasmas

    CERN Document Server

    Kube, Ralph

    2014-01-01

    Particle density fluctuations in the scrape-off layer of magnetically confined plasmas, as measured by gas-puff imaging or Langmuir probes, are modeled as the realization of a stochastic process in which a superposition of pulses with a fixed shape, an exponential distribution of waiting times and amplitudes represents the radial motion of blob-like structures. With an analytic formulation of the process at hand, we derive expressions for the mean-squared error on estimators of sample mean and sample variance as a function of sample length, sampling frequency, and the parameters of the stochastic process. % Employing that the probability distribution function of a particularly relevant shot noise process is given by the gamma distribution, we derive estimators for sample skewness and kurtosis, and expressions for the mean-squared error on these estimators. Numerically generated synthetic time series are used to verify the proposed estimators, the sample length dependency of their mean-squared errors, and thei...

  16. Nonlinear physics and energetic particle transport features of the beam-plasma instability

    CERN Document Server

    Carlevaro, Nakia; Montani, Giovanni; Zonca, Fulvio

    2015-01-01

    In this paper, we study transport features of a one-dimensional beam-plasma system in the presence of multiple resonances. As a model description of the general problem of a warm energetic particle beam, we assume $n$ cold supra-thermal beams and investigate the self-consistent evolution in the presence of the complete spectrum of nearly degenerate Langmuir modes. A qualitative transport estimation is obtained by computing the Lagrangian Coherent Structures of the system on given temporal scales. This leads to the splitting of the phase space into regions where the local transport processes are relatively faster. The general theoretical framework is applied to the case of the nonlinear dynamics of two cold beams, for which numerical simulation results are illustrated and analyzed.

  17. Effect of particle size on the microstructure and thermal conductivity of Al/diamond composites prepared by spark plasma sintering

    Institute of Scientific and Technical Information of China (English)

    CHU Ke; JIA Chengchang; LIANG Xuebing; CHEN Hui; GAO Wenjia

    2009-01-01

    Spark plasma sintering (SPS) was used to fabricate Al/diamond composites. The influence of diamond particle size on the microstrueture and thermal conductivity (TC) of composites was investigated by combining experimental results with model prediction. The results show that both composites with 40 μm particles and 70 μm particles exhibit high density and good TC, and the composite with 70 μm particles indi-cates an excellent TC of 325 W·m~(-1)·K~(-1). Their TCs lay between the theoretical estimated bounds. In contrast, the composite with 100 μm particles demonstrates low density as well as poor TC due to its high porosity and weak interfacial bonding. Its TC is even considerably less than the lower bound of the predicted value. Using larger diamond particles can further enhance thermal conductive performance only based on the premise that highly dense composites of strong interfacial bonding can be obtained.

  18. Detection of prion protein particles in blood plasma of scrapie infected sheep.

    Directory of Open Access Journals (Sweden)

    Oliver Bannach

    Full Text Available Prion diseases are transmissible neurodegenerative diseases affecting humans and animals. The agent of the disease is the prion consisting mainly, if not solely, of a misfolded and aggregated isoform of the host-encoded prion protein (PrP. Transmission of prions can occur naturally but also accidentally, e.g. by blood transfusion, which has raised serious concerns about blood product safety and emphasized the need for a reliable diagnostic test. In this report we present a method based on surface-FIDA (fluorescence intensity distribution analysis, that exploits the high state of molecular aggregation of PrP as an unequivocal diagnostic marker of the disease, and show that it can detect infection in blood. To prepare PrP aggregates from blood plasma we introduced a detergent and lipase treatment to separate PrP from blood lipophilic components. Prion protein aggregates were subsequently precipitated by phosphotungstic acid, immobilized on a glass surface by covalently bound capture antibodies, and finally labeled with fluorescent antibody probes. Individual PrP aggregates were visualized by laser scanning microscopy where signal intensity was proportional to aggregate size. After signal processing to remove the background from low fluorescence particles, fluorescence intensities of all remaining PrP particles were summed. We detected PrP aggregates in plasma samples from six out of ten scrapie-positive sheep with no false positives from uninfected sheep. Applying simultaneous intensity and size discrimination, ten out of ten samples from scrapie sheep could be differentiated from uninfected sheep. The implications for ante mortem diagnosis of prion diseases are discussed.

  19. Influence of Ionization Degrees on the Evolutions of Charged Particles in Atmospheric Plasma at Low Altitude

    Institute of Scientific and Technical Information of China (English)

    PANG Xuexia; DENG Zechao; JIA Pengying; LIANG Weihua; LI Xia

    2012-01-01

    A zero-dimensional model which includes 56 species of reactants and 427 reactions is used to study the behavior of charged particles in atmospheric plasmas with different ionization degrees at low altitude (near 0 km). The constant coefficient nonlinear equations are solved by using the Quasi-steady-state approximation method. The electron lifetimes are obtained for afterglow plasma with different initial values, and the temporal evolutions of the main charged species are presented, which are dominant in reaction processes. The results show that the electron number density decays quickly. The lifetimes of electrons are shortened by about two orders with increasing ionization degree. Electrons then attach to neutral particles and produce negative ions. When the initial electron densities are in the range of 10l~ ~ 1014 cm-3, the negative ions have sufficiently high densities and long lifetimes for air purification, disinfection and sterilization. Electrons, O(2,-), O(4,-) CO(4,-) and CO(3,-) are the dominant negative species when the initial electron density neo ≤ 1013 cm^(-3), and only electrons and CO3 are left when neo 〉 1015 cm^(-3). N(+,2), N+ and O(+,2) are dominant in the positive charges for any ionization degree. Other positive species, such as 0(+,4), N(+,3), NO(+,2), NO(+,2), Ar(+,2) and H3O+. H2O, are dominant only for a certain ionization degree and in a certain period.

  20. Plasma heating in a post eruption Current Sheet: a case study based on ultraviolet, soft, and hard X-ray data

    CERN Document Server

    Susino, Roberto; Krucker, Säm

    2013-01-01

    Off-limb observations of the solar corona after Coronal Mass Ejections (CMEs) often show strong, compact, and persistent UV sources behind the eruption. They are primarily observed by the SOHO/UVCS instrument in the "hot" Fe XVIII {\\lambda}974 {\\AA} line and are usually interpreted as a signature of plasma heating due to magnetic reconnection in the post-CME Current Sheet (CS). Nevertheless, the physical process itself and the altitude of the main energy release are currently not fully understood. In this work, we studied the evolution of plasma heating after the CME of 2004 July 28 by comparing UV spectra acquired by UVCS with soft X-ray (SXR) and hard X-ray (HXR)images of the post-flare loops taken by GOES/SXI and RHESSI. The X-ray data show a long-lasting extended source that is rising upwards, toward the high-temperature source detected by UVCS. UVCS data show the presence of significant non-thermal broadening in the CS (signature of turbulent motions) and a strong density gradient across the CS region. T...

  1. Kinetic Alfven wave instability in a Lorentzian dusty plasma: Non-resonant particle approach

    Energy Technology Data Exchange (ETDEWEB)

    Rubab, N.; Biernat, H. K. [Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, A-8042 Graz (Austria); Institute of Physics, University of Graz, Universitaetplatz 5, A-8010 Graz (Austria); Erkaev, V. [Institute of Computational Modelling, 660036 Krasnoyarsk, Russia and Siberian Federal University, 660041 Krasnoyarsk (Russian Federation); Langmayr, D. [Virtual Vehicle Competence Center (vif), Inffeldgasse 21a, 8010 Graz (Austria)

    2011-07-15

    Analysis of the electromagnetic streaming instability is carried out which is related to the cross field drift of kappa distributed ions. The linear dispersion relation for electromagnetic wave using Vlasov-fluid equations in a dusty plasma is derived. Modified two stream instability (MTSI) in a dusty plasma has been discussed in the limit {omega}{sub pd}{sup 2}/c{sup 2}k{sub perpendicular}{sup 2}<<1. Numerical calculations of the growth rate of instability have been carried out. Growth rates of kinetic Alfven instability are found to be small as compared to MTSI. Maximum growth rates for both instabilities occur in oblique directions for V{sub 0}{>=}V{sub A}. It is shown that the presence of both the charged dust particles and perpendicular ion beam sensibly modify the dispersion relation of low-frequency electromagnetic wave. The dispersion characteristics are found to be insensible to the superthermal character of the ion distribution function. Applications to different intersteller regions are discussed.

  2. Ohm's law for a current sheet

    Science.gov (United States)

    Lyons, L. R.; Speiser, T. W.

    1985-01-01

    The paper derives an Ohm's law for single-particle motion in a current sheet, where the magnetic field reverses in direction across the sheet. The result is considerably different from the resistive Ohm's law often used in MHD studies of the geomagnetic tail. Single-particle analysis is extended to obtain a self-consistency relation for a current sheet which agrees with previous results. The results are applicable to the concept of reconnection in that the electric field parallel to the current is obtained for a one-dimensional current sheet with constant normal magnetic field. Dissipated energy goes directly into accelerating particles within the current sheet.

  3. Effect of Plasma Spheroidization Process on the Microstructure and Crystallographic Phases of Silica, Alumina and Nickel Particles

    Institute of Scientific and Technical Information of China (English)

    HU Peng; YAN Shikai; YUAN Fangli; BAI Liuyang; LI Jinlin; CHEN Yunfa

    2007-01-01

    During the plasma spheroidization process powders undergo different changes in their microstructures and crystal phases. In this paper, simple calculation of heat transfer between the plasma and a suspended particle was performed based on three hypotheses for the purpose of guiding experiments. Experimental investigation of the crystal phases and microstructural changes during the plasma processing was made using silica, alumina and nickel powders as starting materials. It has been revealed from the experimental results that these materials undergo different changes in crystal phases and microstructures, and these changes are essentially determined by the structures, properties and aggregate states of the starting materials.

  4. Wave-particle and wave-wave interactions in hot plasmas: a French historical point of view

    Science.gov (United States)

    Laval, Guy; Pesme, Denis; Adam, Jean-Claude

    2016-11-01

    The first researches on nuclear fusion for energy applications marked the entrance of hot plasmas into the laboratory. It became necessary to understand the behavior of such plasmas and to learn how to manipulate them. Theoreticians and experimentalists, building on the foundations of empirical laws, had to construct this new plasma physics from first principles and to explain the results of more and more complicated experiments. Along this line, two important topics emerged: wave-particle and wave-wave interactions. Here, their history is recalled as it has been lived by a French team from the end of the sixties to the beginning of the twenty-first century.

  5. Charging of small grains in a space plasma: Application to Jovian stream particles

    CERN Document Server

    Dzhanoev, A R; Liu, X; Spahn, F

    2016-01-01

    Most theoretical investigations of dust charging processes in space have treated the current balance condition as independent of grain size. However, for small grains, as they are often observed in space environments, a dependence on grain size is expected due to secondary electron emission (SEE). Here, by the term "small" we mean a particle size comparable to the typical penetration depth for given primary electron energy. The results are relevant for the dynamics of small, charged dust particles emitted by the volcanic moon Io, which form the Jovian dust streams. We revise the theory of charging of small (sub-micron sized) micrometeoroids to take into account a high production of secondary electrons for small grains immersed in an isotropic flux of electrons. We apply our model to obtain an improved estimate for the charge of the dust streams leaving the Jovian system, detected by several spacecraft. For the Jupiter plasma environment we derive the surface potential of grains composed of NaCl (believed to b...

  6. Modeling particle-induced electron emission in a simplified plasma Test Cell

    Energy Technology Data Exchange (ETDEWEB)

    Giuliano, Paul N.; Boyd, Iain D. [Department of Aerospace Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2013-03-21

    Particle-induced electron emission (PIE) is modeled in a simplified, well-characterized plasma Test Cell operated at UCLA. In order for PIE to be a useful model in this environment, its governing equations are first reduced to lower-order models which can be implemented in a direct simulation Monte Carlo and Particle-in-Cell framework. These reduced-order models are described in full and presented as semi-empirical models. The models are implemented to analyze the interaction of low- and high-energy ({approx}1-2 keV) xenon ions and atoms with the stainless steel electrodes of the Test Cell in order to gain insight into the emission and transport of secondary electrons. Furthermore, there is a lack of data for xenon-stainless steel atom- and ion-surface interactions for similar environments. Using experimental data as a reference, both total yields and emitted electron energy distribution functions can be deduced by observing sensitivities of current collection results to these numerical models and their parameters.

  7. Numerical study of the effect of gas temperature on the time for onset of particle nucleation in argon-silane low-pressure plasmas

    CERN Document Server

    Bhandarkar, U; Girshick, S L

    2003-01-01

    Particle nucleation in silane plasmas has attracted interest for the past decade, both due to the basic problems of plasma chemistry involved and the importance of silane plasmas for many applications. A better understanding of particle nucleation may facilitate the avoidance of undesirable particle contamination as well as enable the controlled production of nanoparticles for novel applications. While understanding of particle nucleation has significantly advanced over the past years, a number of questions have not been resolved. Among these is the delay of particle nucleation with an increasing gas temperature, which has been observed in experiments in argon-silane plasmas. We have developed a quasi-one-dimensional model to simulate particle nucleation and growth in silane containing plasmas. In this paper we present a comparative study of the various effects that have been proposed as explanations for the nucleation delay. Our results suggest that the temperature dependence of the Brownian diffusion coeffi...

  8. SciDAC Center for Gyrokinetic Particle Simulation of Turbulent Transport in Burning Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zhihong [Univ. of California, Irvine, CA (United States)

    2013-12-18

    During the first year of the SciDAC gyrokinetic particle simulation (GPS) project, the GPS team (Zhihong Lin, Liu Chen, Yasutaro Nishimura, and Igor Holod) at the University of California, Irvine (UCI) studied the tokamak electron transport driven by electron temperature gradient (ETG) turbulence, and by trapped electron mode (TEM) turbulence and ion temperature gradient (ITG) turbulence with kinetic electron effects, extended our studies of ITG turbulence spreading to core-edge coupling. We have developed and optimized an elliptic solver using finite element method (FEM), which enables the implementation of advanced kinetic electron models (split-weight scheme and hybrid model) in the SciDAC GPS production code GTC. The GTC code has been ported and optimized on both scalar and vector parallel computer architectures, and is being transformed into objected-oriented style to facilitate collaborative code development. During this period, the UCI team members presented 11 invited talks at major national and international conferences, published 22 papers in peer-reviewed journals and 10 papers in conference proceedings. The UCI hosted the annual SciDAC Workshop on Plasma Turbulence sponsored by the GPS Center, 2005-2007. The workshop was attended by about fifties US and foreign researchers and financially sponsored several gradual students from MIT, Princeton University, Germany, Switzerland, and Finland. A new SciDAC postdoc, Igor Holod, has arrived at UCI to initiate global particle simulation of magnetohydrodynamics turbulence driven by energetic particle modes. The PI, Z. Lin, has been promoted to the Associate Professor with tenure at UCI.

  9. Energy spectra of plasma sheet ions and electrons from about 50 eV/e to about 1 MeV during plamsa temperature transitions

    Science.gov (United States)

    Christon, S. P.; Mitchell, D. G.; Williams, D. J.; Frank, L. A.; Huang, C. Y.; Eastman, T. E.

    1988-01-01

    ISEE-1 charged-particle measurements obtained during eight plasma temperature transitions (PTTs) in 1978-1979 are compiled in tables and graphs and analyzed in detail, comparing the ion and electron differential energy spectra with the predictions of theoretical models. PTTs are defined as approximately 1-h periods of low bulk plasma velocity and steadily increasing or decreasing thermal energy. A Maxwellian distribution is found to be inadequate in describing the PTT energy spectra, but velocity-exponential and kappa distributions are both successful, the latter especially at higher energies. The power-law index kappa varies from PTT to PTT, but the high-energy spectral index and overall shape of the distribution remain constant during a PTT; both spatial and temporal effects are observed.

  10. The Plasma Simulation Code: A modern particle-in-cell code with patch-based load-balancing

    Science.gov (United States)

    Germaschewski, Kai; Fox, William; Abbott, Stephen; Ahmadi, Narges; Maynard, Kristofor; Wang, Liang; Ruhl, Hartmut; Bhattacharjee, Amitava

    2016-08-01

    This work describes the Plasma Simulation Code (PSC), an explicit, electromagnetic particle-in-cell code with support for different order particle shape functions. We review the basic components of the particle-in-cell method as well as the computational architecture of the PSC code that allows support for modular algorithms and data structure in the code. We then describe and analyze in detail a distinguishing feature of PSC: patch-based load balancing using space-filling curves which is shown to lead to major efficiency gains over unbalanced methods and a previously used simpler balancing method.

  11. Heliospheric plasma sheet (HPS) impingement onto the magnetosphere as a cause of relativistic electron dropouts (REDs) via coherent EMIC wave scattering with possible consequences for climate change mechanisms

    Science.gov (United States)

    Tsurutani, B. T.; Hajra, R.; Tanimori, T.; Takada, A.; Bhanu, R.; Mannucci, A. J.; Lakhina, G. S.; Kozyra, J. U.; Shiokawa, K.; Lee, L. C.; Echer, E.; Reddy, R. V.; Gonzalez, W. D.

    2016-10-01

    A new scenario is presented for the cause of magnetospheric relativistic electron decreases (REDs) and potential effects in the atmosphere and on climate. High-density solar wind heliospheric plasmasheet (HPS) events impinge onto the magnetosphere, compressing it along with remnant noon-sector outer-zone magnetospheric 10-100 keV protons. The betatron accelerated protons generate coherent electromagnetic ion cyclotron (EMIC) waves through a temperature anisotropy (T⊥/T|| > 1) instability. The waves in turn interact with relativistic electrons and cause the rapid loss of these particles to a small region of the atmosphere. A peak total energy deposition of 3 × 1020 ergs is derived for the precipitating electrons. Maximum energy deposition and creation of electron-ion pairs at 30-50 km and at Wilcox et al. (1973) noted a correlation between solar wind heliospheric current sheet (HCS) crossings and high atmospheric vorticity centers at 300 mb altitude. Tinsley et al. has constructed a global circuit model which depends on particle precipitation into the atmosphere. Other possible scenarios potentially affecting weather/climate change are also discussed.

  12. On the nature of particle energization via resonant wave-particle interaction in the inhomogeneous magnetospheric plasma

    Directory of Open Access Journals (Sweden)

    D. R. Shklyar

    2011-06-01

    Full Text Available When a quasi-monochromatic wave propagating in an inhomogeneous magnetoplasma has sufficiently large amplitude, there exist phase-trapped resonant particles whose energy increases or decreases depending on the "sign" of inhomogeneity. The variation of energy density of such particles can greatly exceed the wave energy density which contradicts energy conservation under the prevalent assumption that the wave serves as the energy source or sink. We show that, in fact, the energy increase (or decrease of phase-trapped particles is related to energy transfer from (to phase untrapped particles, while the wave basically mediates the energization process. Virtual importance of this comprehension consists in setting proper quantitative constraints on attainable particle energy. The results have immediate applications to at least two fundamental problems in the magnetospheric physics, i.e. particle dynamics in the radiation belts and whistler-triggered emissions.

  13. Stochastic heating of a single Brownian particle by charge fluctuations in a radio-frequency produced plasma sheath.

    Science.gov (United States)

    Schmidt, Christian; Piel, Alexander

    2015-10-01

    The Brownian motion of a single particle in the plasma sheath is studied to separate the effect of stochastic heating by charge fluctuations from heating by collective effects. By measuring the particle velocities in the ballistic regime and by carefully determining the particle mass from the Epstein drag it is shown that for a pressure of 10 Pa, which is typical of many experiments, the proper kinetic temperature of the Brownian particle remains close to the gas temperature and rises only slightly with particle size. This weak effect is confirmed by a detailed model for charging and charge fluctuations in the sheath. A substantial temperature rise is found for decreasing pressure, which approximately shows the expected scaling with p(-2). The system under study is an example for non-equilibrium Brownian motion under the influence of white noise without corresponding dissipation.

  14. Mathematical modeling of motion of interacting particles on the basis of the distribution functions in the plasma arc synthesis of ONS

    Directory of Open Access Journals (Sweden)

    G. V. Abramov

    2012-01-01

    Full Text Available The model of the motion of particles in a plasma arc discharge with binary collisions in the synthesis of carbon nanostructures such as fullerenes and nanotubes Rena. The solution of the system of dimensionless equations of the Vlasov-Poisson equations for the determination of the distribution functions of particles in the plasma.

  15. STUDIES ON SURFACE CHARACTERIZATION AND ECOMATERIAL SHEET DEGRADATION OF BASALT FIBERS BY PLASMA TREATMENTS AND WOOD FIBERS

    Institute of Scientific and Technical Information of China (English)

    Guangjian Wang; Yajie Guo; Deku Shang; linna Hu; Zhenhua Guo; Kailiang Zhang

    2004-01-01

    Plasma surface modification (Argon: Hydrogen =0.6:0.4) of basalt fibers was investigated and the element contents of basalt and wood fibers were determined by X-ray energy dispersion spectroscope (EDS).Configuration of basalt fibers was described by means of confocal Laser Raman microRaman spectrometer and Fourier transform infrared spectroscopy. And the morphology of fiber surface was studied with scanning electron microscope(SEM). The modified samples were characterized by X-ray photoelectron spectra (XPS). The results showed that the roughness of basalt fibers was increased with the increase of exposure time of plasma. At the same time the wettability and surface characteristics such as active groups of NH2, OH were improved as well. Basaltfibers were of good chemical stability, better mechanism intension and thermo-stability etc. They mainly consist of [SiO4]4-,[Si2O6]4-, [Si2O5]2-. Further experiments demostrated that they were degraded into edaphic matrix after use.Therefore, they were environmentally friendly.

  16. STUDIES ON SURFACE CHARACTERIZATION AND ECOMATERIAL SHEET DEGRADATION OF BASALT FIBERS BY PLASMA TREATMENTS AND WOOD FIBERS

    Institute of Scientific and Technical Information of China (English)

    GuangjianWang; YajieGuo; DekuShang; linnaHu; ZhenhuaGuo; KailiangZhang

    2004-01-01

    plasma surtace modification (Argon: Hydrogen=0.6:0.4) of basalt fibers was mvestigated and the element contents of basalt and wood fibers were determined by X-ray energy dispersion spectroscope (EDS). configuration of basalt fibers was described by means of confocal Laser Raman microRaman spectrometer and Fourier transform infrared spectroscopy. And the morphology of fiber surface was studied with scanning electron microscope (SEM). The modified samples were characterized by X-ray photoelectron spectra (XPS). The results showed that the roughness of basalt fibers was increased with the increase of exposure time of plasma. At the same time the wettability and surface characteristics such as active groups of NH2, OH were improved as well. Basalt fibers were of good chemical stability, better mechanism intension and thermo-stability etc. They mainly consist of [SiO4]4-, [Si2O6]4-,[Si2O5]2-. Further experiments demostrated that they were degraded into edaphic matrix after use. Therefore, they were environmentally friendly.

  17. Particle-in-cell modeling for MJ scale dense plasma focus with varied anode shape

    Energy Technology Data Exchange (ETDEWEB)

    Link, A., E-mail: link6@llnl.gov; Halvorson, C., E-mail: link6@llnl.gov; Schmidt, A. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Hagen, E. C. [National Security Technologies, Las Vegas, NV 89030 (United States); Rose, D. V.; Welch, D. R. [Voss Scientific LLC, Albuquerque NM 87108 (United States)

    2014-12-15

    Megajoule scale dense plasma focus (DPF) Z-pinches with deuterium gas fill are compact devices capable of producing 10{sup 12} neutrons per shot but past predictive models of large-scale DPF have not included kinetic effects such as ion beam formation or anomalous resistivity. We report on progress of developing a predictive DPF model by extending our 2D axisymmetric collisional kinetic particle-in-cell (PIC) simulations from the 4 kJ, 200 kA LLNL DPF to 1 MJ, 2 MA Gemini DPF using the PIC code LSP. These new simulations incorporate electrodes, an external pulsed-power driver circuit, and model the plasma from insulator lift-off through the pinch phase. To accommodate the vast range of relevant spatial and temporal scales involved in the Gemini DPF within the available computational resources, the simulations were performed using a new hybrid fluid-to-kinetic model. This new approach allows single simulations to begin in an electron/ion fluid mode from insulator lift-off through the 5-6 μs run-down of the 50+ cm anode, then transition to a fully kinetic PIC description during the run-in phase, when the current sheath is 2-3 mm from the central axis of the anode. Simulations are advanced through the final pinch phase using an adaptive variable time-step to capture the fs and sub-mm scales of the kinetic instabilities involved in the ion beam formation and neutron production. Validation assessments are being performed using a variety of different anode shapes, comparing against experimental measurements of neutron yield, neutron anisotropy and ion beam production.

  18. Detecting nanoparticulate silver using single-particle inductively coupled plasma-mass spectrometry.

    Science.gov (United States)

    Mitrano, Denise M; Lesher, Emily K; Bednar, Anthony; Monserud, Jon; Higgins, Christopher P; Ranville, James F

    2012-01-01

    The environmental prevalence of engineered nanomaterials, particularly nanoparticulate silver (AgNP), is expected to increase substantially. The ubiquitous use of commercial products containing AgNP may result in their release to the environment, and the potential for ecological effects is unknown. Detecting engineered nanomaterials is one of the greatest challenges in quantifying their risks. Thus, it is imperative to develop techniques capable of measuring and characterizing exposures, while dealing with the innate difficulties of nanomaterial detection in environmental samples, such as low-engineered nanomaterial concentrations, aggregation, and complex matrices. Here the authors demonstrate the use of inductively coupled plasma-mass spectrometry, operated in a single-particle counting mode (SP-ICP-MS), to detect and quantify AgNP. In the present study, two AgNP products were measured by SP-ICP-MS, including one of precisely manufactured size and shape, as well as a commercial AgNP-containing health food product. Serial dilutions, filtration, and acidification were applied to confirm that the method detected particles. Differentiation of dissolved and particulate silver (Ag) is a feature of the technique. Analysis of two wastewater samples demonstrated the applicability of SP-ICP-MS at nanograms per liter Ag concentrations. In this pilot study, AgNP was found at 100 to 200 ng/L in the presence of 50 to 500 ng/L dissolved Ag. The method provides the analytical capability to monitor Ag and other metal and metal oxide nanoparticles in fate, transport, stability, and toxicity studies using a commonly available laboratory instrument. Rapid throughput and element specificity are additional benefits of SP-ICP-MS as a measurement tool for metal and metal oxide engineered nanoparticles. Copyright © 2011 SETAC.

  19. Particle flux at the outlet of an Ecr plasma source; Flujos de particulas a la salida de una fuente de plasma ECR

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez T, C.; Gonzalez D, J. [ININ, Departamento de Fisica, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2000-07-01

    The necessity of processing big material areas this has resulted in the development of plasma sources with the important property to be uniform in these areas. Also the continuous diminution in the size of substrates to be processed have stimulated the study of models which allow to predict the control of energy and the density of the ions and neutral particles toward the substrate. On the other hand, there are other applications of the plasma sources where it is very necessary to understand the effects generated by the energetic fluxes of ions and neutrals. These fluxes as well as another beneficial effects can improve the activation energy for the formation and improvement of the diffusion processes in the different materials. In this work, using the drift kinetic approximation is described a model to calculate the azimuthal and radial fluxes in the zone of materials processing of an Ecr plasma source type. The results obtained are compared with experimental results. (Author)

  20. Transport of super-thermal particles and their effect on the stability of global modes in fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Schneller, Mirjam Simone

    2013-08-02

    In thermonuclear plasmas, a population of super-thermal particles generated by external heating methods or fusion reactions can lead to the excitation of global instabilities. The transport processes due to nonlinear wave-particle interactions and the consequential particle losses reduce the plasma heating and the efficiency of the fusion reaction rate. Furthermore, these energetic or fast particles may cause severe damages to the wall of the device. This thesis addresses the resonance mechanisms between these energetic particles and global MHD and kinetic MHD waves, employing the hybrid code HAGIS. A systematic investigation of energetic particles resonant with multiple modes (double-resonance) is presented for the first time. The double-resonant mode coupling is modeled for waves with different frequencies in various overlapping scenarios. It is found that, depending on the radial mode distance, double-resonance is able to significantly enhance, both the growth rates and the saturation amplitudes. Small radial mode distances, however can lead to strong nonlinear mode stabilization of a linear dominant mode. For the first time, simulations of experimental conditions in the ASDEX Upgrade fusion device are performed for different plasma equilibria (particularly for different q profiles). An understanding of fast particle behavior for non-monotonic q profiles is important for the development of advanced fusion scenarios. The numerical tool is the extended version of the HAGIS code, which computes the particle motion in the vacuum region between vessel wall in addition to the internal plasma volume. For this thesis, a consistent fast particle distribution function was implemented, to represent the fast particle population generated by the particular heating method (ICRH). Furthermore, HAGIS was extended to use more realistic eigenfunctions, calculated by the gyrokinetic eigenvalue solver LIGKA. One important aim of these simulations is to allow fast ion loss

  1. The component content of active particles in a plasma-chemical reactor based on volume barrier discharge

    Science.gov (United States)

    Soloshenko, I. A.; Tsiolko, V. V.; Pogulay, S. S.; Terent'yeva, A. G.; Bazhenov, V. Yu; Shchedrin, A. I.; Ryabtsev, A. V.; Kuzmichev, A. I.

    2007-02-01

    In this paper the results of theoretical and experimental studies of the component content of active particles formed in a plasma-chemical reactor composed of a multiple-cell generator of active particles, based on volume barrier discharge, and a working chamber are presented. For calculation of the content of uncharged plasma components an approach is proposed which is based on averaging of the power introduced over the entire volume. Advantages of such an approach lie in an absence of fitting parameters, such as the dimensions of microdischarges, their surface density and rate of breakdown. The calculation and the experiment were accomplished with the use of dry air (20% relative humidity) as the plasma generating medium. Concentrations of O3, HNO3, HNO2, N2 O5 and NO3 were measured experimentally in the discharge volume and working chamber for the residence time of particles on a discharge of 0.3 s and more and discharge specific power of 1.5 W cm-3. It has been determined that the best agreement between the calculation and the experiment occurs at calculated gas medium temperatures in the discharge plasma of about 400-425 K, which correspond to the experimentally measured rotational temperature of nitrogen. In most cases the calculated concentrations of O3, HNO3, HNO2, N2O5 and NO3 for the barrier discharge and the working chamber are in fairly good agreement with the respective measured values.

  2. Characterization of High-Velocity Single Particle Impacts on Plasma-Sprayed Ceramic Coatings

    Science.gov (United States)

    Kiilakoski, Jarkko; Lindroos, Matti; Apostol, Marian; Koivuluoto, Heli; Kuokkala, Veli-Tapani; Vuoristo, Petri

    2016-08-01

    High-velocity impact wear can have a significant effect on the lifetime of thermally sprayed coatings in multiple applications, e.g., in the process and paper industries. Plasma-sprayed oxide coatings, such as Cr2O3- and TiO2-based coatings, are often used in these industries in wear and corrosion applications. An experimental impact study was performed on thermally sprayed ceramic coatings using the High-Velocity Particle Impactor (HVPI) at oblique angles to investigate the damage, failure, and deformation of the coated structures. The impact site was characterized by profilometry, optical microscopy, and scanning electron microscopy (SEM). Furthermore, the connection between the microstructural details and impact behavior was studied in order to reveal the damage and failure characteristics at a more comprehensive level. Differences in the fracture behavior were found between the thermally sprayed Cr2O3 and TiO2 coatings, and a concept of critical impact energy is presented here. The superior cohesion of the TiO2 coating inhibited interlamellar cracking while the Cr2O3 coating suffered greater damage at high impact energies. The HVPI experiment has proven to be able to produce valuable information about the deformation behavior of coatings under high strain rates and could be utilized further in the development of wear-resistant coatings.

  3. Energetic particle driven geodesic acoustic mode in a toroidally rotating tokamak plasma

    Science.gov (United States)

    Ren, Haijun

    2017-01-01

    Energetic particle (EP) driven geodesic acoustic modes (EGAMs) in toroidally rotating tokamak plasmas are analytically investigated using the hybrid kinetic-fluid model and gyrokinetic equations. By ignoring high-order terms and ion Landau damping, the kinetic dispersion relation is reduced to the hybrid one in the large safety factor limit. There is one high-frequency branch with a frequency larger than {ωt0} , the transit frequency of EPs with initial energy, which is always stable. Two low-frequency solutions with a frequency smaller than {ωt0} are complex conjugates in the hybrid limit. In the presence of ion Landau damping, the growth rate of the unstable branch is decreased and the damping rate of the damped branch is increased. The toroidal Mach number is shown to increase {{ Ω }\\text{r}} , the normalized real frequency of both branches. Although not affecting the instability critical condition, the Mach number decreases the growth rate when {{ Ω }\\text{r}} is larger than a critical value Ω \\text{r}\\text{cri} and enlarges the growth rate when {{ Ω }\\text{r}}Landau damping effect is negligible for large M. But the discrepancy between the kinetic dispersion relation and the hybrid one becomes ignorable only for q≳ 7 .

  4. Particle transport in a He-microchip plasma atomic emission system with an ultrasonic nebulizer for aqueous sample introduction

    Science.gov (United States)

    Oh, Joosuck; Lim, H. B.

    2008-11-01

    The transport efficiency of dried particles generated from an ultrasonic nebulizer (USN) was studied to improve the analytical performance of a lab-made, He-microchip plasma system, in which a quartz tube (~ 1 mm i.d.) was positioned inside the central channel of a poly(dimethylsiloxane) (PDMS) polymer chip. The polymer microchip plasma has the advantages of low cost, small size, easy handling and design, and self-ignition with long stabilization (> 24 h). However, direct introduction of aqueous solution into the microplasma for the detection of metals remains problematic due to plasma instability. In addition, the much smaller size of the system can cause signal suppression due to low transport efficiency. Therefore, knowledge of particle transport efficiency in this microplasma system is required to enhance the sensitivity and stability. The weight of transported particles in the range of 0.02 to 10 mg m - 3 was measured using a piezobalance with a precision of 0.4-17.8%, depending on the operating conditions. The significant effects of the USN operating conditions and the physical properties of the tubing, namely, length, inner diameter and surface characteristics, on the number of particles transported from the nebulizer to the microplasma were studied. When selected metals, such as Na, Mg and Pb, at a concentration of 5 mg L - 1 were nebulized, transported particles were obtained with a mass range of 0.5-5 mg m - 3 , depending on atomic weights. For application of the He-rf-microplasma, the atomic emission system was optimized by changing both the radio frequency (rf) power (60-200 W) and cooling temperature of the USN (- 12-9 °C). The limits of detection obtained for K, Na and Cu were 0.26, 0.22, and 0.28 mg L - 1 , respectively. These results confirmed the suitable stability and sensitivity of the He-rf-PDMS microchip plasma for application as an atomization source.

  5. Plasma clearance of human low-density lipoprotein in human apolipoprotein B transgenic mice is related to particle diameter.

    Science.gov (United States)

    Berneis, Kaspar; Shames, David M; Blanche, Patricia J; La Belle, Michael; Rizzo, Manfredi; Krauss, Ronald M

    2004-04-01

    To test for intrinsic differences in metabolic properties of low-density lipoprotein (LDL) as a function of particle size, we examined the kinetic behavior of 6 human LDL fractions ranging in size from 251 to 265 A injected intravenously into human apolipoprotein (apo) B transgenic mice. A multicompartmental model was formulated and fitted to the data by standard nonlinear regression using the Simulation, Analysis and Modeling (SAAM II) program. Smaller sized LDL particles (251 to 257 A) demonstrated a significantly slower fractional catabolic rate (FCR) (0.050 +/- 0.045 h(-1)) compared with particles of larger size (262 to 265 A) (0.134 +/- -0.015 h(-1), P particles are cleared more slowly from plasma than larger LDL and are exchanged more slowly with the extravascular space. This might be due to compositional or structural features of smaller LDL that lead to retarded clearance.

  6. Particle in cell calculation of plasma force on a small grain in a non-uniform collisional sheath

    CERN Document Server

    Hutchinson, I H

    2013-01-01

    The plasma force on grains of specified charge and height in a collisional plasma sheath are calculated using the multidimensional particle in cell code COPTIC. The background ion velocity distribution functions for the unperturbed sheath vary substantially with collisionality. The grain force is found to agree quite well with a combination of background electric field force plus ion drag force. However, the drag force must take account of the non-Maxwellian (and spatially varying) ion distribution function, and the collisional drag enhancement. It is shown how to translate the dimensionless results into practical equilibrium including other forces such as gravity.

  7. Low pressure arc discharges with hollow cathodes and their using in plasma generators and charged particle sources

    CERN Document Server

    Vintizenko, L G; Koval, N N; Tolkachev, V S; Lopatin, I V; Shchanin, P M

    2001-01-01

    Paper presents the results of investigation into arc discharges with a hollow cathode generating 10 sup 1 sup 0 -10 sup 1 sup 2 concentration gas-discharge plasma in essential (approx 1 m sup 3) volumes at low (10 sup - sup 2 -1 Pa) pressures and up to 200 A discharge currents. One studied design of discharge systems with heated and cold cathodes their peculiar features, presented the parameters of plasma generators and of charged particle sources based on arc discharges and discussed, as well, the problems of more rational application of those systems in the processes for surface modification of solids

  8. Particle beam experiments for the investigation of plasma-surface interactions: application to magnetron sputtering and polymer treatment

    CERN Document Server

    Corbella, Carles; Kreiter, Oliver; Arcos, Teresa de los; Benedikt, Jan; von Keudell, Achim

    2013-01-01

    A beam experiment is presented to study heterogeneous reactions relevant to plasma-surface interactions. Atom and ion beams are focused onto the sample to expose it to quantified beams of oxygen, nitrogen, hydrogen, noble gas ions and metal vapor. The heterogeneous surface processes are monitored in-situ and in real time by means of a quartz crystal microbalance (QCM) and Fourier transform infrared spectroscopy (FTIR). Two examples illustrate the capabilities of the particle beam setup: oxidation and nitriding of aluminum as a model of target poisoning during reactive magnetron sputtering, and plasma treatment of polymers (PET, PP).

  9. Response of plasma facing components in Tokamaks due to intense energy deposition using Particle-In-Cell (PIC) methods

    Science.gov (United States)

    Genco, Filippo

    Damage to plasma-facing components (PFC) due to various plasma instabilities is still a major concern for the successful development of fusion energy and represents a significant research obstacle in the community. It is of great importance to fully understand the behavior and lifetime expectancy of PFC under both low energy cycles during normal events and highly energetic events as disruptions, Edge-Localized Modes (ELM), Vertical Displacement Events (VDE), and Run-away electron (RE). The consequences of these high energetic dumps with energy fluxes ranging from 10 MJ/m2 up to 200 MJ/m 2 applied in very short periods (0.1 to 5 ms) can be catastrophic both for safety and economic reasons. Those phenomena can cause a) large temperature increase in the target material b) consequent melting, evaporation and erosion losses due to the extremely high heat fluxes c) possible structural damage and permanent degradation of the entire bulk material with probable burnout of the coolant tubes; d) plasma contamination, transport of target material into the chamber far from where it was originally picked. The modeling of off-normal events such as Disruptions and ELMs requires the simultaneous solution of three main problems along time: a) the heat transfer in the plasma facing component b) the interaction of the produced vapor from the surface with the incoming plasma particles c) the transport of the radiation produced in the vapor-plasma cloud. In addition the moving boundaries problem has to be considered and solved at the material surface. Considering the carbon divertor as target, the moving boundaries are two since for the given conditions, carbon doesn't melt: the plasma front and the moving eroded material surface. The current solution methods for this problem use finite differences and moving coordinates system based on the Crank-Nicholson method and Alternating Directions Implicit Method (ADI). Currently Particle-In-Cell (PIC) methods are widely used for solving

  10. Investigation of the near-field structure of jet diffusion flame by the laser sheet method. 1st Report. New seeding method of scattering particles and its application; Laser sheet ho ni yoru funryu kakusan kaen no kibu kozo no kaimei. 1. Atarashii sanran ryushi tenkaho no teian to sono oyo

    Energy Technology Data Exchange (ETDEWEB)

    Noda, S.; Onodera, K.; Kamitakahara, Y.; Onuma, Y. [Toyohashi University of Technology, Aichi (Japan)

    1997-02-25

    The new seeding method of MgO scattering particles based on a laser sheet method was developed, and the near-field structure of jet diffusion flame was studied. This method adds MgO particles (0.2-1.0{mu}m in size) produced by oxidation reaction as scattering particles through combustion of a Mg ribbon in a passage. Since this seeding method of scattering particles can add extreme-densely particles, this method is applicable to not only laser sheet visualization but also laser Doppler velocimeter and concentration measurement. In non-combustion jet formed over a contraction nozzle, coherent vortices are formed in the near field within nearly 8000 in Reynolds number, and the coherent vortices enhance mixing of fuel and air in the process of their linear and nonlinear growth. In the case over 8000 in Reynolds number, the small-scale short-lifetime coherent vortices are formed in the initial development stage of mixed layers, and the whole jet is dominated by irregular turbulent mixing after collapse of the coherent vortices. 14 refs., 8 figs., 1 tab.

  11. Study of energetic particle dynamics in Harbin Dipole eXperiment (HDX) on Space Plasma Environment Research Facility (SPERF)

    Science.gov (United States)

    Zhibin, W.; Xiao, Q.; Wang, X.; Xiao, C.; Zheng, J.; E, P.; Ji, H.; Ding, W.; Lu, Q.; Ren, Y.; Mao, A.

    2015-12-01

    Zhibin Wang1, Qingmei Xiao1, Xiaogang Wang1, Chijie Xiao2, Jinxing Zheng3, Peng E1, Hantao Ji1,5, Weixing Ding4, Quaming Lu6, Y. Ren1,5, Aohua Mao11 Laboratory for Space Environment and Physical Sciences, Harbin Institute of Technology, Harbin, China 150001 2 State Key Lab of Nuclear Physics & Technology, and School of Physics, Peking University, Beijing, China 100871 3ASIPP, Hefei, China, 230031 4University of California at Los Angeles, Los Angeles, CA, 90095 5Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 6University of Science and Technology of China, Hefei, China, 230026 A new terrella device for laboratory studies of space physics relevant to the inner magnetospheric plasmas, Harbin Dipole eXperiment (HDX), is scheduled to be built at Harbin Institute of Technology (HIT), China. HDX is one of two essential parts of Space Plasma Environment Research Facility (SPERF), which is a major national research facility for space physics studies. HDX is designed to provide a laboratory experimental platform to reproduce the earth's magnetospheric structure for investigations on the mechanism of acceleration/loss and wave-particle interaction of energetic particles in radiation belt, and on the influence of magnetic storms on the inner magnetosphere. It can be operated together with Harbin Reconnection eXperiment (HRX), which is another part of SPERF, to study the fundamental processes during interactions between solar wind and Earth's magnetosphere. In this presentation, the scientific goals and experimental plans for HDX, together with the means applied to generate the plasma with desired parameters, including multiple plasma sources and different kinds of coils with specific functions, as well as advanced diagnostics designed to be equipped to the facility for multi-functions, are reviewed. Three typical scenarios of HDX with operations of various coils and plasma sources to study specific physical processes in space plasmas will also be

  12. Effect of Magnetohydrodynamic Perturbations on the Orbit Loss of Alpha Particles in Tokamak Plasma

    Institute of Scientific and Technical Information of China (English)

    邬良能; 俞国扬

    2002-01-01

    We investigate the orbit loss of alpha particles under helical magnetic perturbation in a tokamak. The results show that low-frequency andlow-mode number magnetic perturbation can cause stochastic loss ofalpha particles.This effect is significant for those particles close to the boundary between the transit zone and the trapped zone.The particle loss is sensitive to the phase of the magnetic perturbation, indicating the modulation of the particle loss with respect to magnetic perturbation. It is also found that the precession of the particle banana orbit can even further enhance the particle loss.

  13. Quantum features of a charged particle in ionized plasma controlled by a time-dependent magnetic field

    Directory of Open Access Journals (Sweden)

    Jeong Ryeol eChoi

    2014-08-01

    Full Text Available Quantum characteristics of a charged particle traveling under the influence of an external time-dependent magnetic field in ionized plasma are investigated using the invariant operator method. The Hamiltonian that gives the radial part of the classical equation of motion for the charged particle is dependent on time. The corresponding invariant operator that satisfies Liouville-von Neumann equation is constructed using fundamental relations. The exact radial wave functions are derived by taking advantage of the eigenstates of the invariant operator. Quantum properties of the system is studied using these wave functions. Especially, the time behavior of the radial component of the quantized energy is addressed in detail.

  14. Crossed contributions to electron and heavy-particle transport fluxes for magnetized plasmas in the continuum regime

    Science.gov (United States)

    Scoggins, James B.; Knisely, Carleton P.; Magin, Thierry E.

    2016-11-01

    We propose a unified fluid model for multicomponent plasmas in thermal nonequilibrium accounting for the influence of the electromagnetic field. In a previous work, this model was derived from kinetic theory based on a generalized Chapman-Enskog perturbative solution of the Boltzmann equation, scaled using the ratio of electron to heavy-particle masses. Anisotropic transport properties were derived in terms of bracket integrals. In this work, explicit expressions for asymptotic solutions of the transport properties are derived using a spectral Galerkin projection supplied with Laguerre-Sonine polynomial basis functions, and we analyze the crossed contributions to electron and heavy particle mass and energy fluxes, known as the Kolesnikov effect.

  15. Influence of in-flight particle state diagnostics on properties of plasma sprayed YSZ-CeO2 nanocomposite coatings

    Directory of Open Access Journals (Sweden)

    S. Mantry

    2014-07-01

    Full Text Available This article describes the influence of controlling in-flight hot particle characteristics on properties of plasma sprayed nanostructured yttria stabilized zirconia (YSZ coatings. This article depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on particle temperature, velocity and size of the splat prior to impact on the metallic substrate. Particle temperature measurement is based on two-color pyrometry and particle velocities are measured from the length of the particle traces during known exposure times. The microstructure and adhesion strength of as-sprayed nano-YSZ coatings were studied. Field emission scanning electron microscopy results revealed that morphology of coating exhibits bimodal microstructure consisting of nano-zones reinforced in the matrix of fully melted particles. The coating adhesion strength is noticed to be greatly affected by the melting state of agglomerates. Maximum adhesion strength of 42.39 MPa has been experimentally found out by selecting optimum levels of particle temperature and velocity. The enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nano-zones.

  16. The Plasma Simulation Code: A modern particle-in-cell code with load-balancing and GPU support

    CERN Document Server

    Germaschewski, Kai; Ahmadi, Narges; Wang, Liang; Abbott, Stephen; Ruhl, Hartmut; Bhattacharjee, Amitava

    2013-01-01

    Recent increases in supercomputing power, driven by the multi-core revolution and accelerators such as the IBM Cell processor, graphics processing units (GPUs) and Intel's Many Integrated Core (MIC) technology have enabled kinetic simulations of plasmas at unprecedented resolutions, but changing HPC architectures also come with challenges for writing efficient numerical codes. This paper describes the Plasma Simulation Code (PSC), an explicit, electromagnetic particle-in-cell code with support for different order particle shape functions. We focus on two distinguishing feature of the code: patch-based load balancing using space-filling curves, and support for Nvidia GPUs, which achieves substantial speed-up of up to more than 6x on the Cray XK7 architecture compared to a CPU-only implementation.

  17. Enhanced active aluminum content and thermal behaviour of nano-aluminum particles passivated during synthesis using thermal plasma route

    Science.gov (United States)

    Mathe, Vikas L.; Varma, Vijay; Raut, Suyog; Nandi, Amiya Kumar; Pant, Arti; Prasanth, Hima; Pandey, R. K.; Bhoraskar, Sudha V.; Das, Asoka K.

    2016-04-01

    Here, we report synthesis and in situ passivation of aluminum nanoparticles using thermal plasma reactor. Both air and palmitc acid passivation was carried out during the synthesis in the thermal plasma reactor. The passivated nanoparticles have been characterized for their structural and morphological properties using X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. In order to understand nature of passivation vibrational spectroscopic analysis have been carried out. The enhancement in active aluminum content and shelf life for a palmitic acid passivated nano-aluminum particles in comparison to the air passivated samples and commercially available nano Al powder (ALEX) has been observed. Thermo-gravimetric analysis was used to estimate active aluminum content of all the samples under investigation. In addition cerimetric back titration method was also used to estimate AAC and the shelf life of passivated aluminum particles. Structural, microstructural and thermogravomateric analysis of four year aged passivated sample also depicts effectiveness of palmitic acid passivation.

  18. Simultaneous measurement of electron and heavy particle temperatures in He laser-induced plasma by Thomson and Rayleigh scattering

    Energy Technology Data Exchange (ETDEWEB)

    Dzierzega, K.; Mendys, A.; Zawadzki, W. [Marian Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland); Pokrzywka, B. [Mt. Suhora Observatory, Pedagogical University of Cracow, ul. Podchorazych 2, 30-084 Krakow (Poland); Pellerin, S. [GREMI, site de Bourges, Universite d' Orleans, CNRS, rue Gaston Berger BP 4043, 18028 Bourges (France)

    2013-04-01

    Thomson and Rayleigh scattering methods were applied to quantify the electron and heavy particle temperatures, as well as electron number density, in a laser spark in helium at atmospheric pressure. Plasma was created using 4.5 ns, 25 mJ pulses from Nd:YAG laser at 532 nm. Measurements, performed for the time interval between 20 ns and 800 ns after breakdown, show electron density and temperature to decrease from 7.8 Multiplication-Sign 10{sup 23} m{sup -3} to 2.6 Multiplication-Sign 10{sup 22} m{sup -3} and from 95 900 K to 10 350 K, respectively. At the same time, the heavy particle temperature drops from only 47 000 K down to 4100 K which indicates a two temperature plasma out of local isothermal equilibrium.

  19. Fact Sheets

    Science.gov (United States)

    ... Fact Sheets are available in both English and Spanish and can be downloaded for free. Currently available ... Antiviral Medications to Treat or Prevent Influenza (the Flu) PDF | Espanol PDF Apremilast (Otezla®) PDF | Espanol PDF ...

  20. Convergence of lateral dynamic measurements in the plasma membrane of live cells from single particle tracking and STED-FCS

    DEFF Research Database (Denmark)

    Lagerholm, B. Christoffer; Andrade, Débora M.; Clausen, Mathias P.

    2017-01-01

    Fluorescence correlation spectroscopy (FCS) in combination with the super-resolution imaging method STED (STED-FCS), and single-particle tracking (SPT) are able to directly probe the lateral dynamics of lipids and proteins in the plasma membrane of live cells at spatial scales much below the diff...... embryo fibroblasts results in an unhindered, intra-compartment, diffusion coefficient of ≈0.7-1.0 μm2 s-1, and a compartment size of about 100-150 nm....