WorldWideScience

Sample records for plasma parameters observed

  1. GEOS-1 observations of electrostatic waves, and their relationship with plasma parameters

    International Nuclear Information System (INIS)

    Christiansen, P.J.; Gough, M.P.; Martelli, G.; Beghin, C.; Decreau, P.; Jones, D.

    1978-01-01

    In this paper the authors describe and discuss the occurrence of natural wave emissions detected by GEOS-1 at frequencies above the electron gyrofrequency. The bulk of the data presented comes from the first six months of satellite operation and thus concerns mainly dayside phenomena. A classification of the wave phenomena is developed, and experimental evidence and morphological information relevant to this classification are given. Some preliminary comments on nightside observations are included. The results are discussed, and it is argued that they can be understood as manifestations of electron cyclotron harmonic (Bernstein) wave emission in a plasma parameter range which has only very recently received any theoretical examinations. This theme is further developed in a companion paper (Roennmark et al., 1978). (Auth.)

  2. Getting Ready for BepiColombo: A Modeling Approach to Infer the Solar Wind Plasma Parameters Upstream of Mercury from Magnetic Field Observations

    Science.gov (United States)

    Fatemi, S.; Poirier, N.; Holmström, M.; Wieser, M.; Barabash, S.

    2018-05-01

    We have developed a model to infer the solar wind plasma parameters upstream of Mercury from magnetic field observations in Mercury's magnetosphere. This is important for observations by MESSENGER and the future mission to Mercury, BepiColombo.

  3. Optimization of plasma flow parameters of the magnetoplasma compressor

    International Nuclear Information System (INIS)

    Dojcinovic, I P; Kuraica, M M; Obradovc, B M; Cvetanovic, N; Puric, J

    2007-01-01

    Optimization of the working conditions of the magnetoplasma compressor (MPC) has been performed through analysing discharge and compression plasma flow parameters in hydrogen, nitrogen and argon at different pressures. Energy conversion rate, volt-ampere curve exponent and plasma flow velocities have been studied to optimize the efficiency of energy transfer from the supply source to the plasma. It has been found that the most effective energy transfer from the supply to the plasma is in hydrogen as a working gas at 1000 Pa pressure. It was found that the accelerating regime exists for hydrogen up to 3000 Pa pressures, in nitrogen up to 2000 Pa and in argon up to 1000 Pa pressure. At higher pressures MPC in all the gases works in the decelerating regime. At pressures lower than 200 Pa, high cathode erosion is observed. MPC plasma flow parameter optimization is very important because this plasma accelerating system may be of special interest for solid surface modification and other technology applications

  4. Characterization of hot dense plasma with plasma parameters

    Science.gov (United States)

    Singh, Narendra; Goyal, Arun; Chaurasia, S.

    2018-05-01

    Characterization of hot dense plasma (HDP) with its parameters temperature, electron density, skin depth, plasma frequency is demonstrated in this work. The dependence of HDP parameters on temperature and electron density is discussed. The ratio of the intensities of spectral lines within HDP is calculated as a function of electron temperature. The condition of weakly coupled for HDP is verified by calculating coupling constant. Additionally, atomic data such as transition wavelength, excitation energies, line strength, etc. are obtained for Be-like ions on the basis of MCDHF method. In atomic data calculations configuration interaction and relativistic effects QED and Breit corrections are newly included for HDP characterization and this is first result of HDP parameters from extreme ultraviolet (EUV) radiations.

  5. DAQ system for low density plasma parameters measurement

    International Nuclear Information System (INIS)

    Joshi, Rashmi S.; Gupta, Suryakant B.

    2015-01-01

    In various cases where low density plasmas (number density ranges from 1E4 to 1E6 cm -3 ) exist for example, basic plasma studies or LEO space environment measurement of plasma parameters becomes very critical. Conventional tip (cylindrical) Langmuir probes often result into unstable measurements in such lower density plasma. Due to larger surface area, a spherical Langmuir probe is used to measure such lower plasma densities. Applying a sweep voltage signal to the probe and measuring current values corresponding to these voltages gives V-I characteristics of plasma which can be plotted on a digital storage oscilloscope. This plot is analyzed for calculating various plasma parameters. The aim of this paper is to measure plasma parameters using a spherical Langmuir probe and indigenously developed DAQ system. DAQ system consists of Keithley source-meter and a host system connected by a GPIB interface. An online plasma parameter diagnostic system is developed for measuring plasma properties for non-thermal plasma in vacuum. An algorithm is developed using LabVIEW platform. V-I characteristics of plasma are plotted with respect to different filament current values and different locations of Langmuir probe with reference to plasma source. V-I characteristics is also plotted for forward and reverse voltage sweep generated programmatically from the source meter. (author)

  6. Sensitivity of transient synchrotron radiation to tokamak plasma parameters

    International Nuclear Information System (INIS)

    Fisch, N.J.; Kritz, A.H.

    1988-12-01

    Synchrotron radiation from a hot plasma can inform on certain plasma parameters. The dependence on plasma parameters is particularly sensitive for the transient radiation response to a brief, deliberate, perturbation of hot plasma electrons. We investigate how such a radiation response can be used to diagnose a variety of plasma parameters in a tokamak. 18 refs., 13 figs

  7. Plasma diagnostics discharge parameters and chemistry

    CERN Document Server

    Auciello, Orlando

    1989-01-01

    Plasma Diagnostics, Volume 1: Discharge Parameters and Chemistry covers seven chapters on the important diagnostic techniques for plasmas and details their use in particular applications. The book discusses optical diagnostic techniques for low pressure plasmas and plasma processing; plasma diagnostics for electrical discharge light sources; as well as Langmuir probes. The text also describes the mass spectroscopy of plasmas, microwave diagnostics, paramagnetic resonance diagnostics, and diagnostics in thermal plasma processing. Electrical engineers, nuclear engineers, microwave engineers, che

  8. Measurement of macroscopic plasma parameters with a radio experiment: Interpretation of the quasi-thermal noise spectrum observed in the solar wind

    Science.gov (United States)

    Couturier, P.; Hoang, S.; Meyer-Vernet, N.; Steinberg, J. L.

    1983-01-01

    The ISEE-3 SBH radio receiver has provided the first systematic observations of the quasi-thermal (plasma waves) noise in the solar wind plasma. The theoretical interpretation of that noise involves the particle distribution function so that electric noise measurements with long antennas provide a fast and independent method of measuring plasma parameters: densities and temperatures of a two component (core and halo) electron distribution function have been obtained in that way. The polarization of that noise is frequency dependent and sensitive to the drift velocity of the electron population. Below the plasma frequency, there is evidence of a weak noise spectrum with spectral index -1 which is not yet accounted for by the theory. The theoretical treatment of the noise associated with the low energy (thermal) proton population shows that the moving electrical antenna radiates in the surrounding plasma by Carenkov emission which becomes predominant at the low frequencies, below about 0.1 F sub P.

  9. SEM observations of particle track membrane surfaces modificated using plasma treatment

    International Nuclear Information System (INIS)

    Sartowska, B.; Buczkowski, M.; Starosta, W.

    2003-01-01

    This work presents results of scanning electron microscopy (SEM) observations of 0.4 μm membranes after plasma treatment with different parameters. The morphology changes at the surfaces and at the pore walls were observed. The character of changes in the membrane parameters according to the process conditions was determined

  10. Study of Anti-Hydrogen and Plasma Physics 4.Observation of Antiproton Beams and Nonneutral Plasmas

    CERN Document Server

    Hori, Masaki; Fujiwara, Makoto; Kuroda, Naofumi

    2004-01-01

    Diagnostics of antiproton beams and nonneutral plasmas are described in this chapter. Parallel plate secondary electron emission detectors are used to non-destructively observe the beam position and intensity without loss. Plastic scintillation tracking detectors are useful in determining the position of annihilations of antiprotons in the trap. Three-dimensional imaging of antiprotons in a Penning trap is discussed. The unique capability of antimatter particle imaging has allowed the observation of the spatial distribution of particle loss in a trap. Radial loss is localized to small spots, strongly breaking the azimuthal symmetry expected for an ideal trap. By observing electrostatic eigen-modes of nonneutral plasmas trapped in the Multi-ring electrode trap, the non-destructive measurement of plasma parameters is performed.

  11. North-South asymmetry of interplanetary plasma and solar parameters

    International Nuclear Information System (INIS)

    El-Borie, M. A.

    2001-01-01

    Data of interplanetary plasma (field magnitude, solar wind speed, ion plasma density and temperature) and solar parameters (sunspot number, solar radio flux, and geomagnetic index) over the period 1965-1991, have been used to examine the asymmetry between the solar field north and south of the heliospheric current sheet (HCS). The dependence of N-S asymmetry of field magnitude (B) upon the interplanetary solar polarities is statistically insignificant. There is no clear indication for the presence of N-S asymmetry in the grand-average field magnitude over the solar cycles. During the period 1981-89 (qA<0; negative solar polarity state), the solar plasma was more dense and cooler south of the HCS than north of it. The solar flux component of toward field vector is larger in magnitude than those of away field vector during the qA<0 epoch, and no asymmetry observed in the qA<0 epoch. Furthermore, the sign of the N-S asymmetry in the solar activity depends positively upon the solar polarity state. In addition, it was studied the N-S asymmetry of solar parameters near the HCS, throughout the periods of northern and southern hemispheres were more active than the other. Some asymmetries (with respect to the HCS) in plasma parameters existed during the periods of southern hemisphere predominance

  12. Assessment of thermodynamic parameters of plasma shock wave

    International Nuclear Information System (INIS)

    Vasileva, O V; Isaev, Yu N; Budko, A A; Filkov, A I

    2014-01-01

    The work is devoted to the solution of the one-dimensional equation of hydraulic gas dynamics for the coaxial magneto plasma accelerator by means of Lax-Wendroff modified algorithm with optimum choice of the regularization parameter artificial viscosity. Replacement of the differential equations containing private derivatives is made by finite difference method. Optimum parameter of regularization artificial viscosity is added using the exact known decision of Soda problem. The developed algorithm of thermodynamic parameter calculation in a braking point is proved. Thermodynamic parameters of a shock wave in front of the plasma piston of the coaxial magneto plasma accelerator are calculated on the basis of the offered algorithm. Unstable high-frequency fluctuations are smoothed using modeling and that allows narrowing the ambiguity area. Results of calculation of gas dynamic parameters in a point of braking coincide with literary data. The chart 3 shows the dynamics of change of speed and thermodynamic parameters of a shock wave such as pressure, density and temperature just before the plasma piston

  13. Study of geometrical and operational parameters controlling the low frequency microjet atmospheric pressure plasma characteristics

    International Nuclear Information System (INIS)

    Kim, Dan Bee; Rhee, J. K.; Moon, S. Y.; Choe, W.

    2006-01-01

    Controllability of small size atmospheric pressure plasma generated at low frequency in a pin to dielectric plane electrode configuration was studied. It was shown that the plasma characteristics could be controlled by geometrical and operational parameters of the experiment. Under most circumstances, continuous glow discharges were observed, but both the corona and/or the dielectric barrier discharge characteristics were observed depending on the position of the pin electrode. The plasma size and the rotational temperature were also varied by the parameters. The rotational temperature was between 300 and 490 K, being low enough to treat thermally sensitive materials

  14. Calculation of stationary plasma parameters in an electromagnetic trap

    International Nuclear Information System (INIS)

    Karpukhin, V.I.; Lavrent'ev, O.A.; Sappa, N.N.

    1978-01-01

    The model of energy and particle balance is considered and the numerical calculations for stationary plasma parameters, supported by the electron injection, are obtained for a hypothetical electromagnetic trap with linear dimensions, magnetic field strength and energy contribution to plasma of the order of these parameters for the modern tokamak-type traps. The process of limitation of an effective injection current and energy contribution to plasma caused by returning of electrons to the injector due to diffusion in the velocity space is simulated. In approximation of a classical diffusion dependences are obtained of the effective energy contribution to plasma and of the parameters ntausub(E) and Tsub(i) (n is a plasma density; tausub(E)- energetic lifetime; Tsub(i) ion temperature) on electron injection current and power and on the confining magnetic field strength. It had been established that at classical character of diffusion in electromagnetic trap with above parameters one could obtain stationary plasma with ntausub(E)=10 12 cm -3 s and Tsub(i)=1keV, maintaining only by electron injection

  15. Fast determination of plasma parameters through function parametrization

    International Nuclear Information System (INIS)

    Braams, B.J.; Jilge, W.; Lackner, K.

    1985-09-01

    The method of function parametrization, developed by H. Wind for fast data evaluation in high energy physics, is demonstrated in the context of controlled fusion research. This method relies on a statistical analysis of a large data base of simulated experiments in order to obtain a functional representation for intrinsic physical parameters of a system in terms of the values of the measurements. Rapid determination of characteristic equilibrium parameters of a tokamak discharge is shown to be a particularly indicated application. The method is employed on the ASDEX experiment to determine the following parameters of the plasma: position of the magnetic axis, geometric center, and current center; minor radius, elongation, and area of the plasma column; a normalized safety factor at the plasma boundary; the Shafranov parameter βsub(p)+lsub(i)/2; the flux difference between the plasma boundary and an external reference value; the position of the lower and upper saddle points, and the intersections of the separatrix with the four divertor plates. The relevant measurements consist of three differential poloidal flux measurements, four poloidal field measurements, the current through the multipole shaping coils, and the total plasma current. Function parametrization supplies a very accurate interpretation of these data, which is now used for online data analysis, and is also sufficiently fast to be suitable for real-time control of the plasma. (orig.)

  16. Comparative Study of Plasma Parameters in Olive Ridley (Lepidochelys Olivacea and Hawksbill (Eretmochelys Imbricata During Nesting

    Directory of Open Access Journals (Sweden)

    A.Y.A. Alkindi

    2002-06-01

    Full Text Available The aim of this study is to investigate the role of plasma level parameters during nesting activity and provide data potentially useful to future studies on the dynamics of reproductive and stress hormones in the most endangered sea turtle species in the world. Plasma parameters in the sea turtles, olive ridley (Lipodochelys oliveacea and hawksbill (Eretmochelys imbricata from Masirah Island, Oman, were analyzed relative to nesting stress. To date, no study has been conducted on plasma parameter levels in sea turtles during nesting. Field observations were conducted under ideal temperature conditions. At the time of sampling, there was no significant difference for cloacal, sand, air or water temperature for the two species. Electrolytes (Cl¯, Ca++, K+, Na+ and Mg++, cholesterol, urea, uric acid and osmolarity were measured during nesting. Both species were observed to spend between 1.5 and 2.00 hours on the nesting grounds. Some had successful oviposition and completed all nesting phases, while others with incomplete nesting phases failed to oviposit their  eggs. Under both conditions, the turtles of both species had an exhaustive and stressful nesting exercise. Plasma parameter values, both intra-specifically and inter-specifically, were not significantly different for oviposited and non-oviposited turtles. This may indicate that both species have the same physiological adjustment relative to plasma parameters whether or not the turtles oviposited their eggs.

  17. Correlation of Magnetic Fields with Solar Wind Plasma Parameters at 1AU

    Science.gov (United States)

    Shen, F.

    2017-12-01

    The physical parameters of the solar wind observed in-situ near 1AU have been studied for several decades, and relationships between them, such as the positive correlation between the solar wind plasma temperature T and velocity V, and the negative correlation between density N and velocity V, are well known. However, the magnetic field intensity does not appear to be well correlated with any individual plasma parameter. In this paper, we discuss previously under-reported correlations between B and the combined plasma parameters √NV2 as well as between B and √NT. These two correlations are strong during the periods of corotating interaction regions and high speed streams, moderate during intervals of slow solar wind, and rather poor during the passage of interplanetary coronal mass ejections. The results indicate that the magnetic pressure in the solar wind is well correlated both with the plasma dynamic pressure and the thermal pressure. Then, we employ a 3D MHD model to simulate the formation of the relationships between the magnetic strength B and √NV2 as well as √NT observed at 1AU. The inner boundary condition is derived by empirical models, with the magnetic field and density are optional. Five kinds of boundary conditions at the inner boundary of heliosphere are tested. In the cases that the magnetic field is related to speed at the inner boundary, the correlation coefficients between B and √NV2 as well as between B and √NT are even higher than that in the observational results. At 1AU the simulated radial magnetic field shows little latitude dependence, which matches the observation of Ulysses. Most of the modeled characters in these cases are closer to observation than others. This inner boundary condition may more accurately characterize Sun's magnetic influence on the heliosphere. The new input may be able to improve the simulation of CME propagation in the inner heliosphere and the space weather forecasting.

  18. Spatial and temporal variations of small-scale plasma turbulence parameters in the equatorial electrojet: HF and VHF radar observational results

    Directory of Open Access Journals (Sweden)

    G. Manju

    2005-06-01

    Full Text Available The spatial and temporal variations of various parameters associated with plasma wave turbulence in the equatorial electrojet (EEJ at the magnetic equatorial location of Trivandrum (8.5° N, 77° E; dip 0.5° N are studied for the first time, using co-located HF (18MHz and VHF (54.95MHz coherent backscatter radar observations (daytime in the altitude region of 95-110km, mostly on magnetically quiet days. The derived turbulence parameters are the mean electron density irregularity strength (δn/n, anomalous electron collision frequency (νe* and the corrected east-west electron drift velocity (Vey. The validity of the derived parameters is confirmed using radar data at two different frequencies and comparing with in-situ measurements. The behaviour of δn/n in relation to the backscattered power during weak and strong EEJ conditions is also examined to understand the growth and evolution of turbulence in the electrojet.

  19. Spatial and temporal variations of small-scale plasma turbulence parameters in the equatorial electrojet: HF and VHF radar observational results

    Directory of Open Access Journals (Sweden)

    G. Manju

    2005-06-01

    Full Text Available The spatial and temporal variations of various parameters associated with plasma wave turbulence in the equatorial electrojet (EEJ at the magnetic equatorial location of Trivandrum (8.5° N, 77° E; dip 0.5° N are studied for the first time, using co-located HF (18MHz and VHF (54.95MHz coherent backscatter radar observations (daytime in the altitude region of 95-110km, mostly on magnetically quiet days. The derived turbulence parameters are the mean electron density irregularity strength (δn/n, anomalous electron collision frequency (νe* and the corrected east-west electron drift velocity (Vey. The validity of the derived parameters is confirmed using radar data at two different frequencies and comparing with in-situ measurements. The behaviour of δn/n in relation to the backscattered power during weak and strong EEJ conditions is also examined to understand the growth and evolution of turbulence in the electrojet.

  20. Effect of Equilibrium Flow on Plasma Parameters

    International Nuclear Information System (INIS)

    Mukhopadhyay, S.; Lahiri, S.; Sakanaka, P.H.; Dasgupta, B.

    2003-01-01

    The transition to high confinement modes have been identified with the occurrence of strong shear flow near the plasma boundary. Plasma flow has also been associated with various instabilities, heating and other physical processes. As a result, it has become very important to study the effect of such flows on various plasma parameters. In this paper, we present the numerical solution of plasma equilibrium with incompressible toroidal and poloidal flows in several magnetic confinement configurations including tokamaks. The code, which was reported in the last conference, has been used to solve the problem in both circular and D-shaped devices. A parametric study on the generation of shear flow due to radial electric fields has been carried out. Through this study, it has been possible to generate plasma equilibria having sharp pressure gradients which are remarkably close to those reported in various H-mode experiments. The effects of flow on reverse shear equilibria and on the position of the magnetic axis has been studied. Finally, a detailed study has been carried out to understand the effect of flows on important plasma parameters, such as the poloidal flux function, β, energy confinement time

  1. Measurement of performance parameters of plasma source for plasma opening switch on Qiangguang-Ⅰ generator

    International Nuclear Information System (INIS)

    Luo Weixi; Zeng Zhengzhong; Lei Tianshi; Wang Liangping; Hu Yixiang; Sun Tieping; Huang Tao

    2012-01-01

    The plasma source (cable guns) of the plasma opening switch (POS) on Qiangguang Ⅰ generator was chosen as the study object. The plasma source performance was investigated by using charge collectors. Experimental results show that the plasma ejection density is positively correlated with the structural parameter, the distance between gun core tip and muzzle plane, and the plasma ejection velocity is negatively correlated with the parameter. The increasing rate of plasma ejection density is less than that of drive current. As far as a plasma source with tens of cable plasma guns is concerned, the influence of single cable gun's discharge dispersancy on plasma uniformity is little. Analysis of uncertainty shows that the uncertainty of measurement can be reduced by increasing the number of experiments and averaging the results. The combined standard uncertainty of plasma ejection density is less than 10%. (authors)

  2. Fast determination of plasma parameters

    International Nuclear Information System (INIS)

    Wijnands, T.J.; Parlange, F.; Joffrin, E.

    1995-01-01

    Fast analysis of diagnostic signals of a tokamak discharge is demonstrated by using 4 fundamentally different techniques. A comparison between Function Parametrization (FP), Canonical Correlation Analysis (CCA) and a particular Neural Network (NN) configuration known as the Multi Layer Perceptron (MLP) is carried out, thereby taking a unique linear model based on a Singular Value Decomposition (SVD) as a reference. The various techniques provide all functional representations of characteristic plasma parameters in terms of the values of the measurements and are based on an analysis of a large, experimentally achieved database. A brief mathematical description of the various techniques is given, followed by two particular applications to Tore Supra diagnostic data. The first problem is concerned with the identification of the plasma boundary parameters using the poloidal field and differential poloidal flux measurements. A second application involves the interpretation of line integrated data from the multichannel interfero-polarimeter to obtain the central value of the safety factor. (author) 4 refs.; 3 figs

  3. Coronal mass ejections and disturbances in solar wind plasma parameters in relation with geomagnetic storms

    International Nuclear Information System (INIS)

    Verma, P L; Singh, Puspraj; Singh, Preetam

    2014-01-01

    Coronal Mass Ejections (CMEs) are the drastic solar events in which huge amount of solar plasma materials are ejected into the heliosphere from the sun and are mainly responsible to generate large disturbances in solar wind plasma parameters and geomagnetic storms in geomagnetic field. We have studied geomagnetic storms, (Dst ≤-75 nT) observed during the period of 1997-2007 with Coronal Mass Ejections and disturbances in solar wind plasma parameters (solar wind temperature, velocity, density and interplanetary magnetic field) .We have inferred that most of the geomagnetic storms are associated with halo and partial halo Coronal Mass Ejections (CMEs).The association rate of halo and partial halo coronal mass ejections are found 72.37 % and 27.63 % respectively. Further we have concluded that geomagnetic storms are closely associated with the disturbances in solar wind plasma parameters. We have determined positive co-relation between magnitudes of geomagnetic storms and magnitude of jump in solar wind plasma temperature, jump in solar wind plasma density, jump in solar wind plasma velocity and jump in average interplanetary magnetic field with co-relation co-efficient 0 .35 between magnitude of geomagnetic storms and magnitude of jump in solar wind plasma temperature, 0.19 between magnitude of geomagnetic storms and magnitude of jump in solar wind density, 0.34 between magnitude of geomagnetic storms and magnitude of jump in solar wind plasma velocity, 0.66 between magnitude of geomagnetic storms and magnitude of jump in average interplanetary magnetic field respectively. We have concluded that geomagnetic storms are mainly caused by Coronal Mass Ejections and disturbances in solar wind plasma parameters that they generate.

  4. Investigation of the helicon discharge plasma parameters in a hybrid RF plasma system

    International Nuclear Information System (INIS)

    Aleksandrov, A. F.; Petrov, A. K.; Vavilin, K. V.; Kralkina, E. A.; Neklyudova, P. A.; Nikonov, A. M.; Pavlov, V. B.; Ayrapetov, A. A.; Odinokov, V. V.; Sologub, V. A.; Pavlov, G. Ya.

    2016-01-01

    Results of an experimental study of the helicon discharge plasma parameters in a prototype of a hybrid RF plasma system equipped with a solenoidal antenna are described. It is shown that an increase in the external magnetic field leads to the formation of a plasma column and a shift of the maximum ion current along the discharge axis toward the bottom flange of the system. The shape of the plasma column can be controlled via varying the configuration of the magnetic field.

  5. Investigation of the helicon discharge plasma parameters in a hybrid RF plasma system

    Energy Technology Data Exchange (ETDEWEB)

    Aleksandrov, A. F.; Petrov, A. K., E-mail: alpetrov57@gmail.com; Vavilin, K. V.; Kralkina, E. A.; Neklyudova, P. A.; Nikonov, A. M.; Pavlov, V. B. [Moscow State University, Faculty of Physics (Russian Federation); Ayrapetov, A. A.; Odinokov, V. V.; Sologub, V. A.; Pavlov, G. Ya. [Research Institute of Precision Engineering (Russian Federation)

    2016-03-15

    Results of an experimental study of the helicon discharge plasma parameters in a prototype of a hybrid RF plasma system equipped with a solenoidal antenna are described. It is shown that an increase in the external magnetic field leads to the formation of a plasma column and a shift of the maximum ion current along the discharge axis toward the bottom flange of the system. The shape of the plasma column can be controlled via varying the configuration of the magnetic field.

  6. Investigation of helium plasma stream parameters in experiments on surface modification

    International Nuclear Information System (INIS)

    Bandura, A.N.; Byrka, O.V.; Chebotarev, V.V.; Garkusha, I.E.; Tsarenko, A.V. and eds.

    2005-01-01

    The main objection of this study is adjustment of plasma treatment regimes for different materials that allows achieving optimal thickness of modified layer with simultaneously minimal value of surface roughness. With use of optical spectroscopy, detailed information about the basic plasma parameters - electron density, electron and ion temperatures, plasma stream duration and velocity, was obtained. Integrated spectra of plasma radiation were analyzed. The majority of helium and impurity spectral lines were investigated on a subject of Stark broadening. Plasma pressure and energy density values measured with piezodetectors and calorimeters are in good agreement with plasma parameters obtained by optical techniques

  7. Dependence of electron beam instability growth rates on the beam-plasma system parameters

    International Nuclear Information System (INIS)

    Strangeway, R.J.

    1982-01-01

    Electron beam instabilites are studied by using a simple model for an electron beam streaming through a cold plasma, the beam being of finite width perpendicular to the ambient magnetic field. Through considerations of finite geometry and the coldness of the beam and background plasma, an instability similar to the two stream instability is assumed to be the means for wave growth in the system. Having found the maximum growth rate for one set of beam-plasma system parameters, this maximum growth rate is traced as these parameters are varied. The parameters that describe the system are the beam velocity (v/sub b/), electron gyrofrequency to ambient electron plasma frequency ratio (Ω/sub e//ω/sub p/e), the beam to background number density ratio (n/sub b//n/sub a/), and the beam width (a). When Ω/sub e//ω/sub p/e>1, a mode with Ω/sub e/<ω<ω/sub u/hr is found to be unstable, where Ω is the wave frequency and ω/sub u/hr is the upper hybrid resonance frequency. For low values of n/sub b//n/sub a/ and Ω/sub e/<ω/sub p/e, this mode is still present with ω/sub p/e<ω<ω/sub u/hr. If the beam density is large, n/sub b//n/sub a/approx. =1, the instability occures for frequencies just above the electron gyrofrequency. This mode may well be that observed in laboratory plasma before the system undergoes the beam-plasma discharge. There is another instability present, which occurs for ωapprox. =ω/sub p/e. The growth rates for this mode, which are generally larger than those found for the ωapprox. =ωuhr mode, are only weakly dependent on Ω/sub d//ω/sub p/e. That this mode is not always observed in the laboratory implies that some factors not considered in the present theory suppress this mode, specifically, finite beam length

  8. Low energy plasma observations at synchronous orbit

    International Nuclear Information System (INIS)

    Reasoner, D.L.; Lennartsson, W.

    1977-08-01

    The University of California at San Diego Auroral Particles Experiment on the ATS-6 Satellite in synchronous orbit has detected a low-energy plasma population which is separate and distinct from both the ring current and plasma sheet populations. These observations suggest that this plasma is the outer zone of the plasmasphere. During magnetically active periods, this low energy plasma is often observed flowing sunward. In the dusk sector, enhanced plasma flow is often observed for 1-2 hours prior to the onset of a substorm-associated particle injection. (author)

  9. Dependence of plasma characteristics on dc magnetron sputter parameters

    International Nuclear Information System (INIS)

    Wu, S.Z.

    2005-01-01

    Plasma discharge characteristics of a dc magnetron system were measured by a single Langmuir probe at the center axis of the dual-side process chamber. Plasma potential, floating potential, electron and ion densities, and electron temperature were extracted with varying dc power and gas pressure during sputter deposition of a metal target; strong correlations were shown between these plasma parameters and the sputter parameters. The electron density was controlled mostly by secondary electron generation in constant power mode, while plasma potential reflects the confinement space variation due to change of discharge voltage. When discharge pressure was varied, plasma density increases with the increased amount of free stock molecules, while electron temperature inversely decreased, due to energy-loss collision events. In low-pressure discharges, the electron energy distribution function measurements show more distinctive bi-Maxwellian distribution, with the fast electron temperature gradually decreases with increased gas pressure

  10. The scaling of edge parameters in jet with plasma input power

    International Nuclear Information System (INIS)

    Erents, S.K.; McCracken, G.M.; Harbour, P.J.; Clement, S.; Summers, D.D.R.; Tagle, J.A.; Kock, L. de

    1989-01-01

    The scaling of edge parameters of density and temperature with central density and ohmic power in JET has been presented previously for the discrete limiter geometry and more recently for the new belt limiter configuration. However, the scaling with plasma current (I p ) is difficult to interpret because varying I p does not only change the input power but also the safety factor qs and consequently the SOL thickness. The use of additional heating at constant current allows more direct observation of the effects of changing heating power. In this paper we present data in which the plasma input power is increased by ICRH, (Pt<20MW), using a 3MA target plasma, and compare data for different plasma currents using discrete and belt limiter geometries. Edge data is presented from Langmuir probes in tiles at the top of the torus, when the tokamak is operated in single null magnetic separatrix (divertor) mode, as well as for probes in the main plasma boundary to contrast these data with limiter data. (author) 3 refs., 4 figs

  11. The Plasma Parameters and Geometry of Cool and Warm Active Region Loops

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Haixia; Li, Bo; Huang, Zhenghua; Xia, Lidong; Fu, Hui; Mou, Chaozhou [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, 264209 Shandong (China); Madjarska, Maria S.; Wiegelmann, Thomas [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37077, Göttingen (Germany)

    2017-06-10

    How the solar corona is heated to high temperatures remains an unsolved mystery in solar physics. In the present study we analyze observations of 50 whole active region loops taken with the Extreme-ultraviolet Imaging Spectrometer on board the Hinode satellite. Eleven loops were classified as cool loops (<1 MK) and 39 as warm loops (1–2 MK). We study their plasma parameters, such as densities, temperatures, filling factors, nonthermal velocities, and Doppler velocities. We combine spectroscopic analysis with linear force-free magnetic field extrapolation to derive the 3D structure and positioning of the loops, their lengths and heights, and the magnetic field strength along the loops. We use density-sensitive line pairs from Fe xii, Fe xiii, Si x, and Mg vii ions to obtain electron densities by taking special care of intensity background subtraction. The emission measure loci method is used to obtain the loop temperatures. We find that the loops are nearly isothermal along the line of sight. Their filling factors are between 8% and 89%. We also compare the observed parameters with the theoretical Rosner–Tucker–Vaiana (RTV) scaling law. We find that most of the loops are in an overpressure state relative to the RTV predictions. In a follow-up study, we will report a heating model of a parallel-cascade-based mechanism and will compare the model parameters with the loop plasma and structural parameters derived here.

  12. First observations of partially neutralized and quasineutral plasmas in the Columbia Non-neutral Torus

    Science.gov (United States)

    Sarasola, Xabier; Brenner, Paul; Hahn, Michael; Pedersen, Thomas

    2009-11-01

    The Columbia Non-neutral Torus (CNT) is the first stellarator devoted to the study of pure electron, partially neutralized and positron-electron plasmas. To date, CNT usually operates with electron rich plasmas (with negligible ion density) [1], but a stellarator can also confine plasmas of arbitrary degree of neutralization. In CNT the accumulation of ions alters the equilibrium of electron plasmas and a global instability has been observed when the ion fraction exceeds 10 %. A characterization of this instability is presented in [2], analyzing its parameter dependence and spatial structure (non- resonant with rational surfaces). A new set of experiments is currently underway studying plasmas of arbitrary degree of neutralization, ranging from pure electron to quasineutral plasmas. Basic observations show that the plasma potential decouples from emitter bias when we increase the degree of the neutralization of our plasmas. Partially neutralized plasmas are also characterized by multiple mode behavior with dominant modes between 20 and 200 kHz. When the plasma becomes quasineutral, it reverts to single mode behavior. The first results on partially neutralized plasmas confined on magnetic surfaces will be presented. [1] J. Kremer, PRL 97, (2006) 095003 [2] Q. Marksteiner, PRL 100 (2008) 065002

  13. Typical parameters of the plasma chemical similarity in non-isothermal reactive plasmas

    International Nuclear Information System (INIS)

    Gundermann, S.; Jacobs, H.; Miethke, F.; Rutsher, A.; Wagner, H.E.

    1996-01-01

    The substance of physical similarity principles is contained in parameters which govern the comparison of different realizations of a model device. Because similarity parameters for non-isothermal plasma chemical reactors are unknown to a great extent, an analysis of relevant equations is given together with some experimental results. Modelling of the reactor and experimental results for the ozone synthesis are presented

  14. RF plasma parameter determination by a Langmuir multipoint double probe array

    International Nuclear Information System (INIS)

    Rojas-Olmedo, I A; López-Callejas, R; De la Piedad-Beneitez, A; Valencia-Alvarado, R; Peña-Eguiluz, R; Mercado-Cabrera, A; Barocio, S R; Muñoz-Castro, A E; Rodríguez-Méndez, B G

    2012-01-01

    A multipoint double Langmuir (MDL) probe system, which is exempt from interference, has been designed and assembled to be applied to an RF plasma. The system provides the measurement of fundamental plasma parameters such as density, temperature, plasma potential, etc. on the basis of the Bohm Approximation Theory and the Orbital Movement Limit. Thus, one pair of the MDL system is selected so as to consider the right plasma parameters within the prevailing pressure-power intervals. Both the hardware and software of the system have been applied to the modification of material properties by means of the PIII process.

  15. Plasma waves observed by sounding rockets

    International Nuclear Information System (INIS)

    Kimura, I.

    1977-01-01

    Observations of plasma wave phenomena have been conducted with several rockets launched at Kagoshima Space Center, Kyushu, Japan, and at Showa Base, Antarctica. This report presents some results of the observations in anticipation of having valuable comments from other plasma physicists, especially from those who are concerned with laboratory plasma. In the K-9M-41 rocket experiment, VLF plasma waves were observed. In this experiment, the electron beam of several tens of uA was emitted from a hot cathode when a positive dc bias changing from 0 to 10V at 1V interval each second was applied to a receiving dipole antenna. The discrete emissions with 'U' shaped frequency spectrum were observed for the dc bias over 3 volts. The U emissions appeared twice per spin period of the rocket. Similar rocket experiment was performed at Showa Base using a loop and dipole antenna and without hot cathode. Emissions were observed with varying conditions. At present, the authors postulate that such emissions may be produced just in the vicinity of a rocket due to a kind of wake effect. (Aoki, K.)

  16. Study of plasma parameters influencing fractionation in laser ablation-inductively coupled plasma-mass spectrometry

    Science.gov (United States)

    Gäckle, M.; Merten, D.

    2010-12-01

    Methods permitting to test the influence of the matrix as well as of its local and temporal distribution on the plasma conditions in laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) are developed. For this purpose, the MS interface is used as plasma probe allowing to investigate the average plasma condition within the ICP zone observed in terms of temporal and spatial distribution of the matrix. Inserted matrix particles, particularly when being atomized and ionized, can cause considerable changes in both electron density and plasma temperature thus influencing the ionization equilibrium of the individual analytes. In this context, the plasma probe covers a region of the plasma for which no local thermodynamic equilibrium can be assumed. The differences in temperature, identified within the region of the plasma observed, amounted up to 3000 K. While in the central region conditions were detected that would not allow efficient atomization and ionization of the matrix, these conditions improve considerably towards the margin of the area observed. Depending on the nature as well as on the temporally and locally variable density of the matrix, this can lead to varying intensity ratios of the analytes and explain fractionation effects. By means of a derived equation it is shown that the deviation of the intensity ratio from the concentration ratio turns out to be more serious the higher the difference of the ionization potential of the analytes observed, the lower the plasma temperature and the higher the matrix concentration within the area observed.

  17. On the distribution of plasma parameters in RF glow discharge

    International Nuclear Information System (INIS)

    Ning Cheng; Liu Zuli; Liu Donghui; Han Caiyuan.

    1993-01-01

    A self-consistent numerical model based on the two-fluid equations for describing the transport of charged particles in the RF glow discharge is presented. For a plasma generator filled with low-pressure air and parallel-plate electrodes, the model is numerical solved. The space-time distribution of parameters and the spatial distribution of some time-averaged parameters in plasma, which show the physical picture of the RF glow discharge, are obtained

  18. A proposed method for fast determination of plasma parameters

    International Nuclear Information System (INIS)

    Braams, B.J.; Lackner, K.

    1984-09-01

    The method of function parametrization, developed and applied by H. Wind for fast data evaluation in high energy physics, is presented in the context of controlled fusion research. This method relies on statistical analysis of a data base of simulated experiments in order to obtain a functional representation for the intrinsic physical parameters of a system in terms of the values of the measurements. Some variations on Wind's original procedure are suggested. A specific application for tokamak experiments would be the determination of certain global parameters of the plasma, characterizing the current profile, shape of the cross-section, plasma pressure, and the internal inductance. The relevant measurements for this application include values of the poloidal field and flux external to the plasma, and a diamagnetic measurement. These may be combined with other diagnostics, such as electron-cyclotron emission and laser interferometry, in order to obtain also density and temperature profiles. There appears to be a capability for on-line determination of basic physical parameters, in a millisecond timescale on a minicomputer instead of in seconds on a large mainframe. (orig.)

  19. Ion source plasma parameters measurement based on Langmuir probe with commercial frequency sweep

    International Nuclear Information System (INIS)

    Xie, Y.H.; Hu, C.D.; Liu, S.; Shong, S.H.; Jiang, C.C.; Liu, Z.M.

    2010-01-01

    Langmuir probe is one of the main diagnostic tools to measure the plasma parameters in the ion source. In this article, the commercial frequency power, which is sine wave of 50 Hz, was supplied on the Langmuir probe to measure the plasma parameters. The best feature of this probe sweep voltage is that it does not need extra design. The probe I-V characteristic curve can be got in less than 5 ms and the plasma parameters, the electron temperature and the electron density, varying with the time can be got in one plasma discharge of 400 ms.

  20. Study on spatial distribution of plasma parameters in a magnetized inductively coupled plasma

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, Hee-Woon; Lee, Woohyun; Kim, Ji-Won; Whang, Ki-Woong, E-mail: kwhang@snu.ac.kr [Plasma Laboratory, Inter-University Semiconductor Research Center, Department of Electrical and Computer Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, Hyuk [Samsung Electronics Co., Banwol-dong, Hwaseong 445-701 (Korea, Republic of); Park, Wanjae [Tokyo Electron Miyagi Ltd., Taiwa-cho, Kurokawa-gun, Miyagi 981-3629 (Japan)

    2015-07-15

    Spatial distributions of various plasma parameters such as plasma density, electron temperature, and radical density in an inductively coupled plasma (ICP) and a magnetized inductively coupled plasma (M-ICP) were investigated and compared. Electron temperature in between the rf window and the substrate holder of M-ICP was higher than that of ICP, whereas the one just above the substrate holder of M-ICP was similar to that of ICP when a weak (<8 G) magnetic field was employed. As a result, radical densities in M-ICP were higher than those in ICP and the etch rate of oxide in M-ICP was faster than that in ICP without severe electron charging in 90 nm high aspect ratio contact hole etch.

  1. Revisiting linear plasma waves for finite value of the plasma parameter

    Science.gov (United States)

    Grismayer, Thomas; Fahlen, Jay; Decyk, Viktor; Mori, Warren

    2010-11-01

    We investigate through theory and PIC simulations the Landau-damping of plasma waves with finite plasma parameter. We concentrate on the linear regime, γφB, where the waves are typically small and below the thermal noise. We simulate these condition using 1,2,3D electrostatic PIC codes (BEPS), noting that modern computers now allow us to simulate cases where (nλD^3 = [1e2;1e6]). We study these waves by using a subtraction technique in which two simulations are carried out. In the first, a small wave is initialized or driven, in the second no wave is excited. The results are subtracted to provide a clean signal that can be studied. As nλD^3 is decreased, the number of resonant electrons can be small for linear waves. We show how the damping changes as a result of having few resonant particles. We also find that for small nλD^3 fluctuations can cause the electrons to undergo collisions that eventually destroy the initial wave. A quantity of interest is the the life time of a particular mode which depends on the plasma parameter and the wave number. The life time is estimated and then compared with the numerical results. A surprising result is that even for large values of nλD^3 some non-Vlasov discreteness effects appear to be important.

  2. Plasma Arc Cutting Dimensional Accuracy Optimization employing the Parameter Design approach

    Directory of Open Access Journals (Sweden)

    Kechagias John

    2017-01-01

    Full Text Available Plasma Arc Cutting (PAC is a thermal manufacturing process used for metal plates cutting. This work experimentally investigates the influence of process parameters onto the dimensional accuracy performance of the plasma arc cutting process. The cutting parameters studied were cutting speed (mm/min, torch standoff distance (mm, and arc voltage (volts. Linear dimensions of a rectangular workpiece were measured after PAC cutting following the full factorial design experimental approach. For each one of the three process parameters, three parameter levels were used. Analysis of means (ANOM and analysis of variances (ANOVA were performed in order for the effect of each parameter on the leaner dimensional accuracy to be assessed.

  3. Observed and modelled effects of auroral precipitation on the thermal ionospheric plasma: comparing the MICA and Cascades2 sounding rocket events

    Science.gov (United States)

    Lynch, K. A.; Gayetsky, L.; Fernandes, P. A.; Zettergren, M. D.; Lessard, M.; Cohen, I. J.; Hampton, D. L.; Ahrns, J.; Hysell, D. L.; Powell, S.; Miceli, R. J.; Moen, J. I.; Bekkeng, T.

    2012-12-01

    Auroral precipitation can modify the ionospheric thermal plasma through a variety of processes. We examine and compare the events seen by two recent auroral sounding rockets carrying in situ thermal plasma instrumentation. The Cascades2 sounding rocket (March 2009, Poker Flat Research Range) traversed a pre-midnight poleward boundary intensification (PBI) event distinguished by a stationary Alfvenic curtain of field-aligned precipitation. The MICA sounding rocket (February 2012, Poker Flat Research Range) traveled through irregular precipitation following the passage of a strong westward-travelling surge. Previous modelling of the ionospheric effects of auroral precipitation used a one-dimensional model, TRANSCAR, which had a simplified treatment of electric fields and did not have the benefit of in situ thermal plasma data. This new study uses a new two-dimensional model which self-consistently calculates electric fields to explore both spatial and temporal effects, and compares to thermal plasma observations. A rigorous understanding of the ambient thermal plasma parameters and their effects on the local spacecraft sheath and charging, is required for quantitative interpretation of in situ thermal plasma observations. To complement this TRANSCAR analysis we therefore require a reliable means of interpreting in situ thermal plasma observation. This interpretation depends upon a rigorous plasma sheath model since the ambient ion energy is on the order of the spacecraft's sheath energy. A self-consistent PIC model is used to model the spacecraft sheath, and a test-particle approach then predicts the detector response for a given plasma environment. The model parameters are then modified until agreement is found with the in situ data. We find that for some situations, the thermal plasma parameters are strongly driven by the precipitation at the observation time. For other situations, the previous history of the precipitation at that position can have a stronger

  4. Dependence of the source performance on plasma parameters at the BATMAN test facility

    Science.gov (United States)

    Wimmer, C.; Fantz, U.

    2015-04-01

    The investigation of the dependence of the source performance (high jH-, low je) for optimum Cs conditions on the plasma parameters at the BATMAN (Bavarian Test MAchine for Negative hydrogen ions) test facility is desirable in order to find key parameters for the operation of the source as well as to deepen the physical understanding. The most relevant source physics takes place in the extended boundary layer, which is the plasma layer with a thickness of several cm in front of the plasma grid: the production of H-, its transport through the plasma and its extraction, inevitably accompanied by the co-extraction of electrons. Hence, a link of the source performance with the plasma parameters in the extended boundary layer is expected. In order to characterize electron and negative hydrogen ion fluxes in the extended boundary layer, Cavity Ring-Down Spectroscopy and Langmuir probes have been applied for the measurement of the H- density and the determination of the plasma density, the plasma potential and the electron temperature, respectively. The plasma potential is of particular importance as it determines the sheath potential profile at the plasma grid: depending on the plasma grid bias relative to the plasma potential, a transition in the plasma sheath from an electron repelling to an electron attracting sheath takes place, influencing strongly the electron fraction of the bias current and thus the amount of co-extracted electrons. Dependencies of the source performance on the determined plasma parameters are presented for the comparison of two source pressures (0.6 Pa, 0.45 Pa) in hydrogen operation. The higher source pressure of 0.6 Pa is a standard point of operation at BATMAN with external magnets, whereas the lower pressure of 0.45 Pa is closer to the ITER requirements (p ≤ 0.3 Pa).

  5. Dependence of the source performance on plasma parameters at the BATMAN test facility

    International Nuclear Information System (INIS)

    Wimmer, C.; Fantz, U.

    2015-01-01

    The investigation of the dependence of the source performance (high j H − , low j e ) for optimum Cs conditions on the plasma parameters at the BATMAN (Bavarian Test MAchine for Negative hydrogen ions) test facility is desirable in order to find key parameters for the operation of the source as well as to deepen the physical understanding. The most relevant source physics takes place in the extended boundary layer, which is the plasma layer with a thickness of several cm in front of the plasma grid: the production of H − , its transport through the plasma and its extraction, inevitably accompanied by the co-extraction of electrons. Hence, a link of the source performance with the plasma parameters in the extended boundary layer is expected. In order to characterize electron and negative hydrogen ion fluxes in the extended boundary layer, Cavity Ring-Down Spectroscopy and Langmuir probes have been applied for the measurement of the H − density and the determination of the plasma density, the plasma potential and the electron temperature, respectively. The plasma potential is of particular importance as it determines the sheath potential profile at the plasma grid: depending on the plasma grid bias relative to the plasma potential, a transition in the plasma sheath from an electron repelling to an electron attracting sheath takes place, influencing strongly the electron fraction of the bias current and thus the amount of co-extracted electrons. Dependencies of the source performance on the determined plasma parameters are presented for the comparison of two source pressures (0.6 Pa, 0.45 Pa) in hydrogen operation. The higher source pressure of 0.6 Pa is a standard point of operation at BATMAN with external magnets, whereas the lower pressure of 0.45 Pa is closer to the ITER requirements (p ≤ 0.3 Pa)

  6. Plasma Observations During the Mars Atmospheric Plume Event of March-April 2012

    Science.gov (United States)

    Andrews, D. J.; Barabash, S.; Edberg, N. J. T.; Gurnett, D. A.; Hall, B. E. S.; Holmstrom, M.; Lester, M.; Morgan, D. D.; Opgenoorth, H. J.; Ramstad, R.; hide

    2016-01-01

    We present initial analysis and conclusions from plasma observations made during the reported Mars Dust plume event of March - April 2012. During this period, multiple independent amateur observers detected a localized, high-altitude plume over the Martian dawn terminator [Sanchez-Lavega7 et al., Nature, 2015, doi:10.1038nature14162], the origin of which remains to be explained. We report on in-situ measurements of ionospheric plasma density and solar wind parameters throughout this interval made by Mars Express, obtained over the surface region, but at the opposing terminator. We tentatively conclude that the formation and/or transport of this plume to the altitudes where it was observed could be due in part the result of a large interplanetary coronal mass ejection (ICME) encountering the Martian system. Interestingly, we note that a similar plume detection in May 1997 may also have been associated with a large ICME impact at Mars.

  7. Plasma Arc Cutting Dimensional Accuracy Optimization employing the Parameter Design approach

    OpenAIRE

    Kechagias John; Petousis Markos; Vidakis Nectarios; Mastorakis Nikos

    2017-01-01

    Plasma Arc Cutting (PAC) is a thermal manufacturing process used for metal plates cutting. This work experimentally investigates the influence of process parameters onto the dimensional accuracy performance of the plasma arc cutting process. The cutting parameters studied were cutting speed (mm/min), torch standoff distance (mm), and arc voltage (volts). Linear dimensions of a rectangular workpiece were measured after PAC cutting following the full factorial design experimental approach. For ...

  8. Plasma jet source parameter optimisation and experiments on injection into Globus-M spherical tokamak

    International Nuclear Information System (INIS)

    Gusev, V.K.; Petrov, Yu.V.; Sakharov, N.V.; Semenov, A.A.; Voronin, A.V.

    2005-01-01

    Results of theoretical and experimental research on the plasma sources and injection of plasma and gas jet produced by the modified source into tokamak Globus-M are presented. An experimental test stand was developed for investigation of intense plasma jet generation. Optimisation of pulsed coaxial accelerator parameters by means of analytical calculations is performed with the aim of achieving the highest flow velocity at limited coaxial electrode length and discharge current. The optimal parameters of power supply to generate a plasma jet with minimal impurity contamination and maximum flow velocity were determined. A comparison of experimental and calculation results is made. Plasma jet parameters are measured, such as: impurity species content, pressure distribution across the jet, flow velocity, plasma density, etc. Experiments on the interaction of a higher kinetic energy plasma jet with the magnetic field and plasma of the Globus-M tokamak were performed. Experimental results on plasma and gas jet injection into different Globus-M discharge phases are presented and discussed. Results are presented on the investigation of plasma jet injection as the source for discharge breakdown, plasma current startup and initial density rise. (author)

  9. Effect of solar wind plasma parameters on space weather

    International Nuclear Information System (INIS)

    Rathore, Balveer S.; Gupta, Dinesh C.; Kaushik, Subhash C.

    2015-01-01

    Today's challenge for space weather research is to quantitatively predict the dynamics of the magnetosphere from measured solar wind and interplanetary magnetic field (IMF) conditions. Correlative studies between geomagnetic storms (GMSs) and the various interplanetary (IP) field/plasma parameters have been performed to search for the causes of geomagnetic activity and develop models for predicting the occurrence of GMSs, which are important for space weather predictions. We find a possible relation between GMSs and solar wind and IMF parameters in three different situations and also derived the linear relation for all parameters in three situations. On the basis of the present statistical study, we develop an empirical model. With the help of this model, we can predict all categories of GMSs. This model is based on the following fact: the total IMF B total can be used to trigger an alarm for GMSs, when sudden changes in total magnetic field B total occur. This is the first alarm condition for a storm's arrival. It is observed in the present study that the southward B z component of the IMF is an important factor for describing GMSs. A result of the paper is that the magnitude of B z is maximum neither during the initial phase (at the instant of the IP shock) nor during the main phase (at the instant of Disturbance storm time (Dst) minimum). It is seen in this study that there is a time delay between the maximum value of southward B z and the Dst minimum, and this time delay can be used in the prediction of the intensity of a magnetic storm two-three hours before the main phase of a GMS. A linear relation has been derived between the maximum value of the southward component of B z and the Dst, which is Dst = (−0.06) + (7.65) B z +t. Some auxiliary conditions should be fulfilled with this, for example the speed of the solar wind should, on average, be 350 km s −1 to 750 km s −1 , plasma β should be low and, most importantly, plasma temperature

  10. Investigation of shock compressed plasma parameters by interaction with magnetic field

    International Nuclear Information System (INIS)

    Dudin, S. V.; Fortov, V. E.; Gryaznov, V. K.; Mintsev, V. B.; Shilkin, N. S.; Ushnurtsev, A. E.

    1998-01-01

    The Hall effect parameters in shock compressed air, helium and xenon have been estimated and results of experiments with air and helium plasma are presented. Explosively driven shock tubes were used for the generation of strong shock waves. To obtain magnetic field a solenoid was winded over the shock tube. Calculations of dense shock compressed plasma parameters were carried out to plan the experiments. In the experiments with the magnetic field of ∼5 T it was found, that air plasma slug was significantly heated by the whirlwind electrical field. The reflected shock waves technique was used in the experiments with helium. Results on measurements of electrical conductivity and electron concentration of helium are presented

  11. Experimental study on plasma parameters in the mushroom limiter shadow in the T-10 tokamak

    International Nuclear Information System (INIS)

    Alferov, A.A.; Vershkov, V.A.; Grashin, S.A.; Chankin, A.V.

    1988-01-01

    Plasma parameters in the shadow of mashroom limiter installed in the lower tokamak outlet are studied. Investigation into asymmetry of plasma fluxes to the ion and electrone limiter sides leads to a consumption concerning two meachanisms of its occurrance-toroidal plasma rotation and prevailing plasma departure to the wall through the external torus encirclement. Asymmetry of plasma drift potentials near the limiter observed during the experiment leads to current drift through the limiter close to Spitzer j s one. It is shown that with the increase of mean plasma density the plasma density in the limiter channels grows and its temperature is decreased so the charged particle losses for the limiter are weakly dependent on the mean density which is connected with plasma confinement degradation under the density reduction. A complete flux of charged particles to the limiter is comparable to their flux from plasma filament. Plasma flux into the channels is close to ambipolar one and the power fluxes to neutralization plates are of the order of 10 j s Te/e. Neutral gas pressure dependence in the volume under the limiter on the plasma fluxes to channels is nonlinear, the maximum pressure achieves 3x10 -2 T

  12. High-speed photographic observation of plasma-limiter interactions in ISX-B

    International Nuclear Information System (INIS)

    Clausing, R.E.; Emerson, L.C.; Heatherly, L.

    1981-01-01

    High-speed motion pictures confirm that arcing occurs during periods of plasma instability in ISX-B. Various types of plasma-limiter interactions are described and illustrated. Arcing and other visible phenomena are correlated to plasma parameters

  13. Thermodynamics of strongly coupled repulsive Yukawa particles in ambient neutralizing plasma: Thermodynamic instability and the possibility of observation in fine particle plasmas

    International Nuclear Information System (INIS)

    Totsuji, Hiroo

    2008-01-01

    The thermodynamics is analyzed for a system composed of particles with hard cores, interacting via the repulsive Yukawa potential (Yukawa particulates), and neutralizing ambient (background) plasma. An approximate equation of state is given with proper account of the contribution of ambient plasma and it is shown that there exists a possibility for the total isothermal compressibility of Yukawa particulates and ambient plasma to diverge when the coupling between Yukawa particulates is sufficiently strong. In this case, the system undergoes a transition into separated phases with different densities and we have a critical point for this phase separation. Examples of approximate phase diagrams related to this transition are given. It is emphasized that the critical point can be in the solid phase and we have the possibility to observe a solid-solid phase separation. The applicability of these results to fine particle plasmas is investigated. It is shown that, though the values of the characteristic parameters are semiquantitative due to the effects not described by this model, these phenomena are expected to be observed in fine particle plasmas, when approximately isotropic bulk systems are realized with a very strong coupling between fine particles.

  14. Thermodynamics of strongly coupled repulsive Yukawa particles in ambient neutralizing plasma: Thermodynamic instability and the possibility of observation in fine particle plasmas

    Science.gov (United States)

    Totsuji, Hiroo

    2008-07-01

    The thermodynamics is analyzed for a system composed of particles with hard cores, interacting via the repulsive Yukawa potential (Yukawa particulates), and neutralizing ambient (background) plasma. An approximate equation of state is given with proper account of the contribution of ambient plasma and it is shown that there exists a possibility for the total isothermal compressibility of Yukawa particulates and ambient plasma to diverge when the coupling between Yukawa particulates is sufficiently strong. In this case, the system undergoes a transition into separated phases with different densities and we have a critical point for this phase separation. Examples of approximate phase diagrams related to this transition are given. It is emphasized that the critical point can be in the solid phase and we have the possibility to observe a solid-solid phase separation. The applicability of these results to fine particle plasmas is investigated. It is shown that, though the values of the characteristic parameters are semiquantitative due to the effects not described by this model, these phenomena are expected to be observed in fine particle plasmas, when approximately isotropic bulk systems are realized with a very strong coupling between fine particles.

  15. The Influence of the Axial Magnetic Field Upon-the Coaxial Plasma Gun Parameters

    International Nuclear Information System (INIS)

    El-Aragi, G.M.; EL-Demrdash, A.

    2001-01-01

    This study concerns with the influence of an applied axial magnetic field upon the electrical parameters of a coaxial plasma gun device. The experimental results are investigated with 0.5 KJ plasma gun device operated with argon gas at a pressure of 3.5 Torr. An axial time independent magnetic field with intensity of 550 G is introduced along the plasma current sheath axial region, within the annular space between the two coaxial electrodes. From the measurements of the discharge current I(t) and the voltage V(t), the electrical discharge parameters of the plasma gun device and the plasma current sheath implosion velocity are estimated, in normal mode of plasma gun operation and in the mode of presence external axial magnetic field. A comparison between these two modes is studied

  16. A study of evolution/suppression parameters of equatorial postsunset plasma instability

    Directory of Open Access Journals (Sweden)

    O. S. Oyekola

    2009-01-01

    Full Text Available Evening equatorial pre-reversal vertical ion E×B drift (VZP and the peak of the ionospheric F2 maximum altitude (hmF2P of the postsunset equatorial F-layer, which are the essential parameters requisite for the generation or inhibition of postsunset bottomside equatorial irregularities were deduced from ionosonde observations made in the Africa region (Ouagadougou: ~3° N dip latitude between January 1987 and December 1990 for solar activity minimum, medium, and maxima (F10.7=85, 141, 214, and 190, respectively for quiet geomagnetic conditions. We investigate variations of evening equatorial pre-reversal drift and the corresponding altitude at four levels of solar activity. Our observations show strong variations with solar variability. Correlation analysis between these parameters indicates that the correlation coefficient value between hmF2P versus VZP decreases considerably with increasing solar flux value. There seems to be no significant link between these parameters under high solar activity, especially for solar intensity F10.7>200 units. We conclude that meridional neutral wind in the F-region contributes substantially to the variations of the pre-reversal vertical plasma drifts enhancement and the peak hmF2, particularly the electrodynamics during twilight high solar flux conditions.

  17. Plasma Distribution in Mercury's Magnetosphere Derived from MESSENGER Magnetometer and Fast Imaging Plasma Spectrometer Observations

    Science.gov (United States)

    Korth, Haje; Anderson, Brian J.; Gershman, Daniel J.; Raines, Jim M.; Slavin, James A.; Zurbuchen, Thomas H.; Solomon, Sean C.; McNutt, Ralph L.

    2014-01-01

    We assess the statistical spatial distribution of plasma in Mercury's magnetosphere from observations of magnetic pressure deficits and plasma characteristics by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. The statistical distributions of proton flux and pressure were derived from 10months of Fast Imaging Plasma Spectrometer (FIPS) observations obtained during the orbital phase of the MESSENGER mission. The Magnetometer-derived pressure distributions compare favorably with those deduced from the FIPS observations at locations where depressions in the magnetic field associated with the presence of enhanced plasma pressures are discernible in the Magnetometer data. The magnitudes of the magnetic pressure deficit and the plasma pressure agree on average, although the two measures of plasma pressure may deviate for individual events by as much as a factor of approximately 3. The FIPS distributions provide better statistics in regions where the plasma is more tenuous and reveal an enhanced plasma population near the magnetopause flanks resulting from direct entry of magnetosheath plasma into the low-latitude boundary layer of the magnetosphere. The plasma observations also exhibit a pronounced north-south asymmetry on the nightside, with markedly lower fluxes at low altitudes in the northern hemisphere than at higher altitudes in the south on the same field line. This asymmetry is consistent with particle loss to the southern hemisphere surface during bounce motion in Mercury's offset dipole magnetic field.

  18. Plasma parameters effects on the properties, aging and stability behaviors of allylamine plasma coated ultra-high molecular weight polyethylene (UHMWPE) films

    Energy Technology Data Exchange (ETDEWEB)

    Aziz, Gaelle, E-mail: gaelle.aziz@ugent.be; Thukkaram, Monica; De Geyter, Nathalie; Morent, Rino

    2017-07-01

    Highlights: • Medium to atmospheric pressure DBD is used to deposit amino rich films. • Process parameters affect the films’ surface chemical and physical properties. • High deposition rates can be reached by varying the power and/or monomer flow rate. • High amino selectivity (NH{sub 2}/N in %) is obtained at low powers and high monomer concentration. • Aging and stability behaviors of the deposited coatings can be controlled by carefully choosing the plasma parameters. - Abstract: In this work, a dielectric barrier discharge (DBD) operated at medium to atmospheric pressure has been used for the deposition of thin polyallylamine (PAA) films on ultra-high molecular weight polyethylene (UHMWPE) substrates. The effect of treatment time (1–5 min), discharge power (5.7–24.0 W), monomer concentration (1–2 g/h) and pressure (10–100 kPa) on the films properties, aging and stability behaviors have been investigated. The used characterization techniques are X-ray photoelectron spectroscopy, water contact angle and optical reflectance spectroscopy. In this paper, it is shown that plasma treatment time does not affect the coatings chemistry; whereas plasma power, monomer concentration and pressure control the coatings properties. It is also shown that the deposition rate of the deposited films changes with varying W/FM values. At low W/FM values, high deposition rates of up to 2 nm/s are observed. Plasma treatments were also characterized by their amino efficiency ([NH{sub 2}]/[C] in %) and amino selectivity ([NH{sub 2}]/[N] in %). Depending on the used parameters, these varied between 12.3% and 20% and between 71.2% and 91.1%, respectively. For the aging study, coatings that preserved most of their hydrophilicity were obtained at power ≤11.3 W, monomer concentration ≥1.5 g/h and pressure ≥50 kPa. For the stability study, coatings that showed the highest [N] (%) and lowest percentage of thickness decrease were obtained at ≤2 min, 24.0 W, 1 g/h and

  19. Simultaneous measurement of 3 fluctuating plasma parameters

    International Nuclear Information System (INIS)

    Carlson, A.; Giannone, L.

    1991-01-01

    Langmuir triple probes can provide simultaneous measurements of n e , T e and V pl with good temporal and spatial resolution, and therefore are especially suited to detailed investigations of plasma turbulence in the scrape-off-layer. Unfortunately, the finite tip separation coupled with the fluctuating gradients prevents a simple interpretation of the results. We have developed a method using, essentially, two or more triple probes, which allows a good estimate of the three plasma parameters and their spatial derivatives at each point of time (assuming tip separation is much less than correlation length and dimensionless fluctuation levels are much less than unity). In particular, we can unambiguously measure the temperature fluctuations and the turbulent particle and heat flux. (author) 1 fig

  20. Simultaneous measurement of 3 fluctuating plasma parameters

    International Nuclear Information System (INIS)

    Carlson, A.; Giannone, L.

    1991-01-01

    Langmuir triple probes can provide simultaneous measurements of n e , T e , and V pl with good temporal and spatial resolution, and therefore are especially suited to detailed investigations of plasma turbulence in the scrape-off-layer. Unfortunately, the finite tip separation coupled with the fluctuating gradients prevents a simple interpretation of the results. We have developed a method using, essentially, two or more triple probes, which allows a good estimate of the three plasma parameters and their spatial derivatives at each point of time (assuming tip separation is much less than correlation length and dimensionless fluctuation levels are much less than unity). In particular, we can unambiguously measure the temperature fluctuations and the turbulent particle and heat flux. (orig.)

  1. Simultaneous measurement of 3 fluctuating plasma parameters

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, A; Giannone, L. (Max-Planck-Institut fuer Plasmaphysik, Garching (Germany))

    1991-01-01

    Langmuir triple probes can provide simultaneous measurements of n[sub e], T[sub e] and V[sub pl] with good temporal and spatial resolution, and therefore are especially suited to detailed investigations of plasma turbulence in the scrape-off-layer. Unfortunately, the finite tip separation coupled with the fluctuating gradients prevents a simple interpretation of the results. We have developed a method using, essentially, two or more triple probes, which allows a good estimate of the three plasma parameters and their spatial derivatives at each point of time (assuming tip separation is much less than correlation length and dimensionless fluctuation levels are much less than unity). In particular, we can unambiguously measure the temperature fluctuations and the turbulent particle and heat flux. (author) 1 fig.

  2. Determination of Stark parameters by cross-calibration in a multi-element laser-induced plasma

    Science.gov (United States)

    Liu, Hao; Truscott, Benjamin S.; Ashfold, Michael N. R.

    2016-05-01

    We illustrate a Stark broadening analysis of the electron density Ne and temperature Te in a laser-induced plasma (LIP), using a model free of assumptions regarding local thermodynamic equilibrium (LTE). The method relies on Stark parameters determined also without assuming LTE, which are often unknown and unavailable in the literature. Here, we demonstrate that the necessary values can be obtained in situ by cross-calibration between the spectral lines of different charge states, and even different elements, given determinations of Ne and Te based on appropriate parameters for at least one observed transition. This approach enables essentially free choice between species on which to base the analysis, extending the range over which these properties can be measured and giving improved access to low-density plasmas out of LTE. Because of the availability of suitable tabulated values for several charge states of both Si and C, the example of a SiC LIP is taken to illustrate the consistency and accuracy of the procedure. The cross-calibrated Stark parameters are at least as reliable as values obtained by other means, offering a straightforward route to extending the literature in this area.

  3. A lumped parameter model of plasma focus

    International Nuclear Information System (INIS)

    Gonzalez, Jose H.; Florido, Pablo C.; Bruzzone, H.; Clausse, Alejandro

    1999-01-01

    A lumped parameter model to estimate neutron emission of a plasma focus (PF) device is developed. The dynamic of the current sheet is calculated using a snowplow model, and the neutron production with the thermal fusion cross section for a deuterium filling gas. The results were contrasted as a function of the filling pressure with experimental measurements of a 3.68 KJ Mather-type PF. (author)

  4. Optimization of process parameters for spark plasma sintering of nano structured SAF 2205 composite

    Directory of Open Access Journals (Sweden)

    Samuel Ranti Oke

    2018-04-01

    Full Text Available This research optimized spark plasma sintering (SPS process parameters in terms of sintering temperature, holding time and heating rate for the development of a nano-structured duplex stainless steel (SAF 2205 grade reinforced with titanium nitride (TiN. The mixed powders were sintered using an automated spark plasma sintering machine (model HHPD-25, FCT GmbH, Germany. Characterization was performed using X-ray diffraction and scanning electron microscopy. Density and hardness of the composites were investigated. The XRD result showed the formation of FeN0.068. SEM/EDS revealed the presence of nano ranged particles of TiN segregated at the grain boundaries of the duplex matrix. A decrease in hardness and densification was observed when sintering temperature and heating rate were 1200 °C and 150 °C/min respectively. The optimum properties were obtained in composites sintered at 1150 °C for 15 min and 100 °C/min. The composite grades irrespective of the process parameters exhibited similar shrinkage behavior, which is characterized by three distinctive peaks, which is an indication of good densification phenomena. Keywords: Spark plasma sintering, Duplex stainless steel (SAF 2205, Titanium nitride (TiN, Microstructure, Density, Hardness

  5. Scaling laws of design parameters for plasma wakefield accelerators

    International Nuclear Information System (INIS)

    Uhm, Han S.; Nam, In H.; Suk, Hyyong

    2012-01-01

    Simple scaling laws for the design parameters of plasma wakefield accelerators were obtained using a theoretical model, which were confirmed via particle simulation studies. It was found that the acceleration length was given by Δx=0.804λ p /(1−β g ), where λ p is the plasma wavelength and β g c the propagation velocity of the ion cavity. The acceleration energy can also be given by ΔE=(γ m −1)mc 2 =2.645mc 2 /(1−β g ), where m is the electron rest mass. As expected, the acceleration length and energy increase drastically as β g approached unity. These simple scaling laws can be very instrumental in the design of better-performing plasma wakefield accelerators. -- Highlights: ► Simple scaling laws for the design parameters of laser wakefield accelerators were obtained using a theoretical model. ► The scaling laws for acceleration length and acceleration energy were compared with particle-in-cell simulation results. ► The acceleration length and the energy increase drastically as β g approaches unity. ► These simple scaling laws can be very instrumental in the design of laser wakefield accelerators.

  6. Spectroscopic observations of an arc-plasma accelerator

    International Nuclear Information System (INIS)

    Clothiaux, E.J.

    1990-01-01

    Spectra from in-bore and from the muzzle flash of an arc-plasma accelerator have been observed, and a strong absorption in the uv is observed in-bore. High pressure at the wall of the arc-plasma accelerator, >800 Bar, suggests a high on-axis equilibrium temperature and a high opacity. Time-resolved measurements of the in-bore emission, at four spectral points, give a peak temperature at the accelerator wall of ≅200,000 o K. (author)

  7. Cluster observation of plasma flow reversal in the magnetotail during a substorm

    Directory of Open Access Journals (Sweden)

    A. T. Y. Lui

    2006-08-01

    Full Text Available We investigate in detail a reversal of plasma flow from tailward to earthward detected by Cluster at the downstream distance of ~19 RE in the midnight sector of the magnetotail on 22 August 2001. This flow reversal was accompanied by a sign reversal of the Bz component and occurred during the late substorm expansion phase as revealed by simultaneous global view of auroral activity from IMAGE. We examine the associated Hall current system signature, current density, electric field, Lorentz force, and current dissipation/dynamo term, the last two parameters being new features that have not been studied previously for plasma flow reversals. It is found that (1 there was no clear quadrupole Hall current system signature organized by the flow reversal time, (2 the x-component of the Lorentz force did not change sign while the other two did, (3 the timing sequence of flow reversal from the Cluster configuration did not match tailward motion of a single plasma flow source, (4 the electric field was occasionally dawnward, producing a dynamo effect, and (5 the electric field was occasionally larger at the high-latitude plasma sheet than near the neutral sheet. These observations are consistent with the current disruption model for substorms in which these disturbances are due to shifting dominance of multiple current disruption sites and turbulence at the observing location.

  8. Spectroscopic observations of an arc-plasma accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Clothiaux, E.J. (Auburn Univ., AL (USA). Dept. of Physics)

    Spectra from in-bore and from the muzzle flash of an arc-plasma accelerator have been observed, and a strong absorption in the uv is observed in-bore. High pressure at the wall of the arc-plasma accelerator, >800 Bar, suggests a high on-axis equilibrium temperature and a high opacity. Time-resolved measurements of the in-bore emission, at four spectral points, give a peak temperature at the accelerator wall of {approx equal}200,000{sup o}K. (author).

  9. Global parameter optimization of a Mather-type plasma focus in the framework of the Gratton–Vargas two-dimensional snowplow model

    International Nuclear Information System (INIS)

    Auluck, S K H

    2014-01-01

    Dense plasma focus (DPF) is known to produce highly energetic ions, electrons and plasma environment which can be used for breeding short-lived isotopes, plasma nanotechnology and other material processing applications. Commercial utilization of DPF in such areas would need a design tool that can be deployed in an automatic search for the best possible device configuration for a given application. The recently revisited (Auluck 2013 Phys. Plasmas 20 112501) Gratton–Vargas (GV) two-dimensional analytical snowplow model of plasma focus provides a numerical formula for dynamic inductance of a Mather-type plasma focus fitted to thousands of automated computations, which enables the construction of such a design tool. This inductance formula is utilized in the present work to explore global optimization, based on first-principles optimality criteria, in a four-dimensional parameter-subspace of the zero-resistance GV model. The optimization process is shown to reproduce the empirically observed constancy of the drive parameter over eight decades in capacitor bank energy. The optimized geometry of plasma focus normalized to the anode radius is shown to be independent of voltage, while the optimized anode radius is shown to be related to capacitor bank inductance. (paper)

  10. Plasma line observations in the auroral oval

    International Nuclear Information System (INIS)

    Valladares, C.E.; Kelley, M.C.; Vickrey, J.F.

    1988-01-01

    We report here a series of experiments conducted at the Sondre Stromfjord incoherent scatter radar, aimed at detected enhanced plasma lines associated with midnight sector auroral arcs. Using different receivers, we detected both ion and plasma lines simultaneously. The plasma line signal was recorded with the use of a filter bank of eight frequencies. Plasma lines were found to originate mainly from the topside of the particle-produced E layer. The enhanced plasma lines are sometimes a factor of 100 times larger than the thermal level. Our data show a rapid decay of the plasma lines, however. In some cases, only a 30-s integration time was needed in order to unambiguously detect both upshifted and downshifted lines. The level of the plasma lines reaches values of, for the larger cases, up to 40 0 K above the noise temperature. These are considerably higher than results from prior auroral zone plasma line experiments. In situ observations of enhanced plasma waves in this same region are reported in a companion paper. copyright American Geophysical Union 1988

  11. Triple-probe method applied to the direct display of plasma parameters in a supersonic flowing continuum plasma

    International Nuclear Information System (INIS)

    Ogram, G.L.; Chang, J.; Hobson, R.M.

    1979-01-01

    The calibration of electrostatic triple-probe voltage and current response in a supersonic continuum plasma has been carried out using a low-pressure shock tube. The electron temperature T/sub e/ and charge number density N/sub e/ are compared to probe voltage and current response, respectively, for a useful range of plasma parameters (1 13 13 is the nondimensional probe voltage). The dependence of probe response on Debye ratio R/sub p//lambda/sub D/ and various flow parameters was investigated. The probe voltage response was found to depend significantly on the Debye ratio. Expressions for electron temperature determination by triple probe are presented

  12. Study on the effect of hydrogen addition on the variation of plasma parameters of argon-oxygen magnetron glow discharge for synthesis of TiO2 films

    Directory of Open Access Journals (Sweden)

    Partha Saikia

    2016-04-01

    Full Text Available We report the effect of hydrogen addition on plasma parameters of argon-oxygen magnetron glow discharge plasma in the synthesis of H-doped TiO2 films. The parameters of the hydrogen-added Ar/O2 plasma influence the properties and the structural phases of the deposited TiO2 film. Therefore, the variation of plasma parameters such as electron temperature (Te, electron density (ne, ion density (ni, degree of ionization of Ar and degree of dissociation of H2 as a function of hydrogen content in the discharge is studied. Langmuir probe and Optical emission spectroscopy are used to characterize the plasma. On the basis of the different reactions in the gas phase of the magnetron discharge, the variation of plasma parameters and sputtering rate are explained. It is observed that the electron and heavy ion density decline with gradual addition of hydrogen in the discharge. Hydrogen addition significantly changes the degree of ionization of Ar which influences the structural phases of the TiO2 film.

  13. Cluster observation of plasma flow reversal in the magnetotail during a substorm

    Directory of Open Access Journals (Sweden)

    A. T. Y. Lui

    2006-08-01

    Full Text Available We investigate in detail a reversal of plasma flow from tailward to earthward detected by Cluster at the downstream distance of ~19 RE in the midnight sector of the magnetotail on 22 August 2001. This flow reversal was accompanied by a sign reversal of the Bz component and occurred during the late substorm expansion phase as revealed by simultaneous global view of auroral activity from IMAGE. We examine the associated Hall current system signature, current density, electric field, Lorentz force, and current dissipation/dynamo term, the last two parameters being new features that have not been studied previously for plasma flow reversals. It is found that (1 there was no clear quadrupole Hall current system signature organized by the flow reversal time, (2 the x-component of the Lorentz force did not change sign while the other two did, (3 the timing sequence of flow reversal from the Cluster configuration did not match tailward motion of a single plasma flow source, (4 the electric field was occasionally dawnward, producing a dynamo effect, and (5 the electric field was occasionally larger at the high-latitude plasma sheet than near the neutral sheet. These observations are consistent with the current disruption model for substorms in which these disturbances are due to shifting dominance of multiple current disruption sites and turbulence at the observing location.

  14. Hidden parameters in the plasma deposition of microcrystalline silicon solar cells

    NARCIS (Netherlands)

    van den Donker, M.N.; Rech, B.; Schmitz, R.; Klomfass, J.; Dingemans, G.; Finger, F.; Houben, L.; Kessels, W.M.M.; Sanden, van de M.C.M.

    2007-01-01

    The effect of process parameters on the plasma deposition of µc-Si:H solar cells is reviewed in this article. Several in situ diagnostics are presented, which can be used to study the process stability as an additional parameter in the deposition process. The diagnostics were used to investigate the

  15. Observations of dusty plasmas with magnetized dust grains

    Science.gov (United States)

    Luo, Q.-Z.; D'Angelo, N.

    2000-11-01

    We report a newly observed phenomenon in a dusty plasma device of the \\mbox{Q-machine} type. At low plasma densities the time required by the plasma to return to its no-dust conditions, after the dust dispenser is turned off, can be as long as many tens of seconds or longer. A tentative interpretation of this observation in terms of magnetized dust grains is advanced. It appears that an important loss mechanism of fine dust grains is by ion drag along the magnetic field lines. The effect of ion drag is somewhat counteracted by the -µ∇B force present when the magnetic field has a mirror geometry.

  16. Mode transition of power dissipation and plasma parameters in an asymmetric capacitive discharge

    International Nuclear Information System (INIS)

    Lee, Soo-Jin; Lee, Hyo-Chang; Bang, Jin-young; Oh, Seung-Ju; Chung, Chin-Wook

    2013-01-01

    Electrical characteristics and plasma parameters were experimentally investigated in asymmetric capacitively coupled plasma with various argon gas pressures. At a low discharge current region, the transferred power to the plasma was proportional to the current, while the transferred power increased proportionally to square of the current at a high discharge current region. The mode transition of power dissipation occurred at the lower discharge current region with the high gas pressure. At the low radio-frequency power or low discharge current, the plasma density increased linearly with the discharge current, while at the high power or high discharge current, the rate of an increase in the plasma density depended on the gas pressures. A transition of the discharge resistance was also found when the mode transition of the power dissipation occurred. These changes in the electrical characteristics and the plasma parameters were mainly caused by the power dissipation mode transition from the plasma bulk to the sheath in the capacitive discharge with the asymmetric electrode, which has extremely high self-bias voltages. - Highlights: • Mode transition of the power dissipation in an asymmetrical capacitive discharge • Evolution of the discharge power, electrode voltage, and discharge impedance • Electron temperature and plasma density on the power dissipation mode transition

  17. Temporal evolution of electron energy distribution function and plasma parameters in the afterglow of drifting magnetron plasma

    International Nuclear Information System (INIS)

    Seo, Sang-Hun; In, Jung-Hwan; Chang, Hong-Young

    2005-01-01

    The temporal behaviour of the electron energy distribution function (EEDF) and the plasma parameters such as electron density, electron temperature and plasma and floating potentials in a mid-frequency pulsed dc magnetron plasma are investigated using time-resolved probe measurements. A negative-voltage dc pulse with an average power of 160 W during the pulse-on period, a repetition frequency of 20 kHz and a duty cycle of 50% is applied to the cathode of a planar unbalanced magnetron discharge with a grounded substrate. The measured electron energy distribution is found to exhibit a bi-Maxwellian distribution, which can be resolved with the low-energy electron group and the high-energy tail part during the pulse-on period, and a Maxwellian distribution only with low-energy electrons as a consequence of initially rapid decay of the high-energy tail part during the pulse-off period. This characteristic evolution of the EEDF is reflected in the decay characteristics of the electron density and temperature in the afterglow. These parameters exhibit twofold decay represented by two characteristic decay times of an initial fast decay time τ 1 , and a subsequent slower decay time τ 2 in the afterglow when approximated with a bi-exponential function. While the initial fast decay times are of the order of 1 μs (τ T1 ∼ 0.99 μs and τ N1 ∼ 1.5 μs), the slower decay times are of the order of a few tens of microseconds (τ T2 ∼ 7 μs and τ N2 ∼ 40 μs). The temporal evolution of the plasma parameters are qualitatively explained by considering the formation mechanism of the bi-Maxwellian electron distribution function and the electron transports of these electron groups in bulk plasma

  18. Observation of electron plasma waves in plasma of two-temperature electrons

    International Nuclear Information System (INIS)

    Ikezawa, Shunjiro; Nakamura, Yoshiharu.

    1981-01-01

    Propagation of electron plasma waves in a large and unmagnetized plasma containing two Maxwellian distributions of electrons is studied experimentally. Two kinds of plasma sources which supply electrons of different temperature are used. The temperature ratio is about 3 and the density ratio of hot to cool electrons is varied from 0 to 0.5. A small contamination of hot electrons enhances the Landau damping of the principal mode known as the Bohm-Gross mode. When the density of hot electrons is larger than about 0.2, two modes are observed. The results agree with theoretical dispersion relations when excitation efficiencies of the modes are considered. (author)

  19. A study of evolution/suppression parameters of equatorial postsunset plasma instability

    Directory of Open Access Journals (Sweden)

    O. S. Oyekola

    2009-01-01

    Full Text Available Evening equatorial pre-reversal vertical ion E×B drift (VZP and the peak of the ionospheric F2 maximum altitude (hmF2P of the postsunset equatorial F-layer, which are the essential parameters requisite for the generation or inhibition of postsunset bottomside equatorial irregularities were deduced from ionosonde observations made in the Africa region (Ouagadougou: ~3° N dip latitude between January 1987 and December 1990 for solar activity minimum, medium, and maxima (F10.7=85, 141, 214, and 190, respectively for quiet geomagnetic conditions. We investigate variations of evening equatorial pre-reversal drift and the corresponding altitude at four levels of solar activity. Our observations show strong variations with solar variability. Correlation analysis between these parameters indicates that the correlation coefficient value between hmF2P versus VZP decreases considerably with increasing solar flux value. There seems to be no significant link between these parameters under high solar activity, especially for solar intensity F10.7>200 units. We conclude that meridional neutral wind in the F-region contributes substantially to the variations of the pre-reversal vertical plasma drifts enhancement and the peak hmF2, particularly the electrodynamics during twilight high solar flux conditions.

  20. Parameter identification of chaos system based on unknown parameter observer

    International Nuclear Information System (INIS)

    Wang Shaoming; Luo Haigeng; Yue Chaoyuan; Liao Xiaoxin

    2008-01-01

    Parameter identification of chaos system based on unknown parameter observer is discussed generally. Based on the work of Guan et al. [X.P. Guan, H.P. Peng, L.X. Li, et al., Acta Phys. Sinica 50 (2001) 26], the design of unknown parameter observer is improved. The application of the improved approach is extended greatly. The works in some literatures [X.P. Guan, H.P. Peng, L.X. Li, et al., Acta Phys. Sinica 50 (2001) 26; J.H. Lue, S.C. Zhang, Phys. Lett. A 286 (2001) 148; X.Q. Wu, J.A. Lu, Chaos Solitons Fractals 18 (2003) 721; J. Liu, S.H. Chen, J. Xie, Chaos Solitons Fractals 19 (2004) 533] are only the special cases of our Corollaries 1 and 2. Some observers for Lue system and a new chaos system are designed to test our improved method, and simulations results demonstrate the effectiveness and feasibility of the improved approach

  1. Prospects for observing the magnetorotational instability in the plasma Couette experiment

    Science.gov (United States)

    Flanagan, K.; Clark, M.; Collins, C.; Cooper, C. M.; Khalzov, I. V.; Wallace, J.; Forest, C. B.

    2015-08-01

    Many astrophysical disks, such as protoplanetary disks, are in a regime where non-ideal, plasma-specific magnetohydrodynamic (MHD) effects can significantly influence the behaviour of the magnetorotational instability (MRI). The possibility of studying these effects in the plasma Couette experiment (PCX) is discussed. An incompressible, dissipative global stability analysis is developed to include plasma-specific two-fluid effects and neutral collisions, which are inherently absent in analyses of Taylor-Couette flows (TCFs) in liquid metal experiments. It is shown that with boundary driven flows, a ion-neutral collision drag body force significantly affects the azimuthal velocity profile, thus limiting the flows to regime where the MRI is not present. Electrically driven flow (EDF) is proposed as an alternative body force flow drive in which the MRI can destabilize at more easily achievable plasma parameters. Scenarios for reaching MRI relevant parameter space and necessary hardware upgrades are described.

  2. 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).

  3. Registering parameters and granules of wave observations: IMAGE RPI success story

    Science.gov (United States)

    Galkin, I. A.; Charisi, A.; Fung, S. F.; Benson, R. F.; Reinisch, B. W.

    2015-12-01

    Modern metadata systems strive to help scientists locate data relevant to their research and then retrieve them quickly. Success of this mission depends on the organization and completeness of metadata. Each relevant data resource has to be registered; each content has to be described; each data file has to be accessible. Ultimately, data discoverability is about the practical ability to describe data content and location. Correspondingly, data registration has a "Parameter" level, at which content is specified by listing available observed properties (parameters), and a "Granule" level, at which download links are given to data records (granules). Until recently, both parameter- and granule-level data registrations were accomplished at NASA Virtual System Observatory easily by listing provided parameters and building Granule documents with URLs to the datafile locations, usually those at NASA CDAWeb data warehouse. With the introduction of the Virtual Wave Observatory (VWO), however, the parameter/granule concept faced a scalability challenge. The wave phenomenon content is rich with descriptors of the wave generation, propagation, interaction with propagation media, and observation processes. Additionally, the wave phenomenon content varies from record to record, reflecting changes in the constituent processes, making it necessary to generate granule documents at sub-minute resolution. We will present the first success story of registering 234,178 records of IMAGE Radio Plasma Imager (RPI) plasmagram data and Level 2 derived data products in ESPAS (near-Earth Space Data Infrastructure for e-Science), using the VWO-inspired wave ontology. The granules are arranged in overlapping display and numerical data collections. Display data include (a) auto-prospected plasmagrams of potential interest, (b) interesting plasmagrams annotated by human analysts or software, and (c) spectacular plasmagrams annotated by analysts as publication-quality examples of the RPI science

  4. The Influence of the Axial Magnetic Field Upon- the Coaxial Plasma Gun Parameters

    International Nuclear Information System (INIS)

    El-Aragi, G.M.; El-Demardash, A.

    2001-01-01

    This study concerns with the influence of an applied axial magnetic field upon the electrical parameters and on the brightness (luminance) of argon plasma. The brightness was measured by with a photomultiplier type of IP28 RCA. The experimental results are investigated with plasma gun device operated with argon gas at a pressure of 3.5 Torr. An axial time independent magnetic field with intensity of 550 G is introduced along the plasma current sheath axial region, within the annular space between the two coaxial electrodes. From the measurements of the discharge current I(t) and the voltage V(t), the electrical discharge parameters of the plasma gun device and the plasma current sheath implosion velocity are estimated, in normal mode of plasma gun operation and in the mode of presence external axial magnetic field. A comparison between these two modes is studied. It was found that the thickness of skin-layer δ about 0.01 cm and the wavelength λ, of the perturbation about 1.3 cm i.e. the instability has been satisfied. The growth rate γ of the instability about 10 6 sec -1 . (author)

  5. Observations of dense plasma formation in the vacuum spark

    International Nuclear Information System (INIS)

    Chuaqui, H.; Favre, M.; Wyndham, E.; Aliaga R, R.; Choi, P.; Dumitrescu-Zoita, C.

    1994-01-01

    A series of experimental observations have been performed on the dense plasma formations or Hot Spots generated in the Vacuum Spark. The plasma discharges are driven by a 1.5 Ohm, 120 ns line at currents up to 100 KA. The line may be used to deliver a rectangular current pulse when the line gap is used. Alternatively when the line gap is shorted, the Vacuum Spark itself switches the line. A Nd: Yag Laser, with an energy of 0.5 J in an 8 ns pulse, is used to pre ionizing the discharge. The formation of Hot Spots is studied under a range of different conditions. These include the pre ionizing conditions, as well as the Anode shape and the Anode Cathode separation. The optimization of these parameters permit very reproducible shot to shot behaviour. Of particular interest is the Hot Spot size dependence as a function of its temperature and of time. The use of a new variant on the Pin Hole Camera, the Slit Wire Camera provides a new method of measuring with precision the Hot Spot dimensions in different X-ray emission energy ranges. A quadruple hole Camera is used to measure the temperature of the Hot Spots. The temporal and spatial evolution of the X-ray emission is measured using using a Slit Wire, Scintillator, Fibre Optic, Photomultiplier array. The temporal emission of the X-rays is also observed using an array of PIN X-ray diodes. (author). 5 refs, 6 figs

  6. The effect of plasma parameter on the bootstrap current of fast ions in neutral beam injection

    International Nuclear Information System (INIS)

    Huang Qianhong; Gong Xueyu; Cao Jinjia; Yang Lei

    2014-01-01

    The effect of plasma parameters on the distribution of net current density of fast ions produced by neutral beam injection is investigated in a large-aspect-ratio Tokamak with circular cross-section under specific parameters. Numerical results show that the value of net current density increases with the temperature of plasma increasing and decreases with the density of plasma increasing. The value of net current density is weakly affected by the effective charge number, but the peak of net current density moves towards edge plasma with effective charge number increasing. (authors)

  7. Effects of plasma jet parameters, ionization, thermal conduction, and radiation on stagnation conditions of an imploding plasma liner

    Science.gov (United States)

    Stanic, Milos

    The disciplines of High Energy Density Physics (HEDP) and Inertial Confinement Fusion (ICF) are characterized by hypervelocity implosions and strong shocks. The Plasma Liner Experiment (PLX) is focused on reaching HEDP and/or ICF relevant regimes in excess of 1 Mbar peak pressure by the merging and implosion of discrete plasma jets, as a potentially efficient path towards these extreme conditions in a laboratory. In this work we have presented the first 3D simulations of plasma liner, formation, and implosion by the merging of discrete plasma jets in which ionization, thermal conduction, and radiation are all included in the physics model. The study was conducted by utilizing a smoothed particle hydrodynamics code (SPHC) and was a part of the plasma liner experiment (PLX). The salient physics processes of liner formation and implosion are studied, namely vacuum propagation of plasma jets, merging of the jets (liner forming), implosion (liner collapsing), stagnation (peak pressure), and expansion (rarefaction wave disassembling the target). Radiative transport was found to significantly reduce the temperature of the liner during implosion, thus reducing the thermal expansion rates and leaving more pronounced gradients in the plasma liner during the implosion compared with ideal hydrodynamic simulations. These pronounced gradients lead to a greater sensitivity of initial jet geometry and symmetry on peak pressures obtained. Accounting for ionization and transport, many cases gave higher peak pressures than the ideal hydrodynamic simulations. Scaling laws were developed accordingly, creating a non-dimensional parameter space in which performance of an imploding plasma jet liner can be estimated. It is shown that HEDP regimes could be reached with ≈ 5 MJ of liner energy, which would translate to roughly 10 to 20 MJ of stored (capacitor) energy. This is a potentially significant improvement over the currently available means via ICF of achieving HEDP and nuclear

  8. Cluster and Double Star multipoint observations of a plasma bubble

    Directory of Open Access Journals (Sweden)

    A. P. Walsh

    2009-02-01

    Full Text Available Depleted flux tubes, or plasma bubbles, are one possible explanation of bursty bulk flows, which are transient high speed flows thought to be responsible for a large proportion of flux transport in the magnetotail. Here we report observations of one such plasma bubble, made by the four Cluster spacecraft and Double Star TC-2 around 14:00 UT on 21 September 2005, during a period of southward, but BY-dominated IMF. In particular the first direct observations of return flows around the edges of a plasma bubble, and the first observations of plasma bubble features within 8 RE of the Earth, consistent with MHD simulations (Birn et al., 2004 are presented. The implications of the presence of a strong BY in the IMF and magnetotail on the propagation of the plasma bubble and development of the associated current systems in the magnetotail and ionosphere are discussed. It is suggested that a strong BY can rotate the field aligned current systems at the edges of the plasma bubble away from its duskward and dawnward flanks.

  9. MMS observation of energy conversion and collisionless plasma dissipation channels in the turbulent magnetosheath

    Science.gov (United States)

    Parashar, T.; Yang, Y.; Chasapis, A.; Matthaeus, W. H.

    2017-12-01

    High resolution Magnetospheric Multiscale (MMS) plasma and magnetic field data obtained in the inhomogeneous turbulent magnetosheath directly reveals the exchanges of energy between electromagnetic, flow and random kinetic energy. The parameters that quantify these exchanges are based on standard manipulations of the collisionless Vlasov model of plasma dynamics [1], without appeal to viscous or other closures. No analysis of heat transport or heat conduction is carried out. Several intervals of burst mode data in the magnetosheath are considered. Time series of the work done by the electromagnetic field, and the pressure-stress interaction enable description of the pathways to dissipation in this low collisionality plasma. Using these examples we demonstrate that the pressure-stress interaction provides important information not readily revealed in other diagnostics concerning the physical processes that are observed. This method does not require any specific mechanism for its application such as reconnection or a selected mode, although with increased experience it will be useful in distinguishing among proposed possibilities. [1] Y. Yang et al, Phys. Plasmas 24, 072306 (2017); doi: 10.1063/1.4990421.

  10. Fast non-linear extraction of plasma equilibrium parameters using a neural network mapping

    International Nuclear Information System (INIS)

    Lister, J.B.; Schnurrenberger, H.

    1990-07-01

    The shaping of non-circular plasmas requires a non-linear mapping between the measured diagnostic signals and selected equilibrium parameters. The particular configuration of Neural Network known as the multi-layer perceptron provides a powerful and general technique for formulating an arbitrary continuous non-linear multi-dimensional mapping. This technique has been successfully applied to the extraction of equilibrium parameters from measurements of single-null diverted plasmas in the DIII-D tokamak; the results are compared with a purely linear mapping. The method is promising, and hardware implementation is straightforward. (author) 15 refs., 7 figs

  11. An observational study on the relationship between plasma vitamin ...

    African Journals Online (AJOL)

    ARTICLE. An observational study on the relationship between plasma ... To study plasma vitamin C, oxidative stress, hyperglycaemia, endothelial dysfunction and outcome in septic shock. ..... with critical illness,[6,7,16] and excess losses of.

  12. Plasma parameter estimations for the Large Helical Device based on the gyro-reduced Bohm scaling

    International Nuclear Information System (INIS)

    Okamoto, Masao; Nakajima, Noriyoshi; Sugama, Hideo.

    1991-10-01

    A model of gyro-reduced Bohm scaling law is incorporated into a one-dimensional transport code to predict plasma parameters for the Large Helical Device (LHD). The transport code calculations reproduce well the LHD empirical scaling law and basic parameters and profiles of the LHD plasma are calculated. The amounts of toroidal currents (bootstrap current and beam-driven current) are also estimated. (author)

  13. QSAT: The Satellite for Polar Plasma Observation

    Science.gov (United States)

    Tsuruda, Yoshihiro; Fujimoto, Akiko; Kurahara, Naomi; Hanada, Toshiya; Yumoto, Kiyohumi; Cho, Mengu

    2009-04-01

    This paper introduces QSAT, the satellite for polar plasma observation. The QSAT project began in 2006 as an initiative by graduate students of Kyushu University, and has the potential to contribute greatly to IHY (International Heliophysical Year) by showing to the world the beauty, importance, and relevance of space science. The primary objectives of the QSAT mission are (1) to investigate plasma physics in the Earth’s aurora zone in order to better understand spacecraft charging, and (2) to conduct a comparison of the field-aligned current observed in orbit with ground-based observations. The QSAT project can provide education and research opportunities for students in an activity combining space sciences and satellite engineering. The QSAT satellite is designed to be launched in a piggyback fashion with the Japanese launch vehicle H-IIA. The spacecraft bus is being developed at the Department of Aeronautics and Astronautics of Kyushu University with collaboration of Fukuoka Institute of Technology. Regarding the payload instruments, the Space Environment Research Center of Kyushu University is developing the magnetometers, whereas the Laboratory of Spacecraft Environment Interaction Engineering of Kyushu Institute of Technology is developing the plasma probes. We aim to be ready for launch in 2009 or later.

  14. Experimental observations related to the thermodynamic properties of tokamak plasmas

    International Nuclear Information System (INIS)

    Sozzi, C.; Minardi, E.; Lazzaro, E.; Cirant, S.; Mantica, P.; Esposito, B.; Marinucci, M.; Romanelli, M.; Imbeaux, F.

    2005-01-01

    The coarse-grained tokamak plasma description derived from the magnetic entropy concept presents appealing features as it involves a simple mathematics and it identifies a limited set of characteristic parameters of the macroscopic equilibrium. In this paper a comprehensive review of the work done in order to check the reliability of the Stationary Magnetic Entropy predictions against experimental data collected from different tokamaks, plasma regimes and heating methods is reported. (author)

  15. Nonequilibrium phenomena and determination of plasma parameters in the hot core of the cathode region in free-burning arc discharges

    International Nuclear Information System (INIS)

    Kuehn, Gerrit; Kock, Manfred

    2007-01-01

    We present spectroscopic measurements of plasma parameters (electron density n e , electron temperature T e , gas temperature T g , underpopulation factor b) in the hot-core region in front of the cathode of a low-current, free-burning arc discharge in argon under atmospheric pressure. The discharge is operated in the hot-core mode, creating a hot cathode region with plasma parameters similar to high-current arcs in spite of the fact that we use comparatively low currents (less than 20 A). We use continuum emission and (optically thin) line emission to determine n e and T e . We apply relaxation measurements based on a power-interruption technique to investigate deviations from local thermodynamic equilibrium (LTE). These measurements let us determine the gas temperature T g . All measurements are performed side-on with charge-coupled-device cameras as detectors, so that all measured plasma parameters are spatially resolved after an Abel inversion. This yields the first ever spatially resolved observation of the non-LTE phenomena of the hot core in the near-cathode region of free-burning arcs. The results only partly coincide with previously published predictions and measurements in the literature

  16. EFFECT OF PLASMA CUTTING PARAMETERS UPON SHAPES OF BEARING CURVE OF C45 STEEL SURFACE

    Directory of Open Access Journals (Sweden)

    Agnieszka Skoczylas

    2015-08-01

    Full Text Available The article presents the results of studies on the effect of plasma cutting technological parameters upon the shape of bearing curves and the parameters of the curve. The topography of surface formed by plasma cutting were analyzed. For measuring surface roughness and determining the bearing curve the appliance T8000 RC120 – 400 by Hommel-Etamic was used together with software.

  17. Fast non-linear extraction of plasma equilibrium parameters using a neural network mapping

    International Nuclear Information System (INIS)

    Lister, J.B.; Schnurrenberger, H.

    1991-01-01

    The shaping of non-circular plasmas requires a non-linear mapping between the measured diagnostic signals and selected equilibrium parameters. The particular configuration of neural network known as the multilayer perceptron provides a powerful and general technique for formulating an arbitrary continuous non-linear multi-dimensional mapping. This technique has been successfully applied to the extraction of equilibrium parameters from measurements of single-null diverted plasmas in the DIII-D tokamak; the results are compared with a purely linear mapping. The method is promising, and hardware implementation is straightforward. (author). 17 refs, 8 figs, 2 tab

  18. Cluster observations of near-Earth magnetospheric lobe plasma densities – a statistical study

    Directory of Open Access Journals (Sweden)

    K. R. Svenes

    2008-09-01

    Full Text Available The Cluster-mission has enabled a study of the near-Earth magnetospheric lobes throughout the waning part of solar cycle 23. During the first seven years of the mission the satellites crossed this region of space regularly from about July to October. We have obtained new and more accurate plasma densities in this region based on spacecraft potential measurements from the EFW-instrument. The plasma density measurements are found by converting the potential measurements using a functional relationship between these two parameters. Our observations have shown that throughout this period a full two thirds of the measurements were contained in the range 0.007–0.092 cm−3 irrespective of solar wind conditions or geomagnetic activity. In fact, the most probable density encountered was 0.047 cm−3, staying roughly constant throughout the entire observation period. The plasma population in this region seems to reflect an equilibrium situation in which the density is independent of the solar wind condition or geomagnetic activity. However, the high density tail of the population (ne>0.2 cm−3 seemed to decrease with the waning solar cycle. This points to a source region influenced by the diminishing solar UV/EUV-intensity. Noting that the quiet time polar wind has just such a development and that it is magnetically coupled to the lobes, it seems likely to assume that this is a prominent source for the lobe plasma.

  19. Observations and Simulations of Formation of Broad Plasma Depletions Through Merging Process

    Science.gov (United States)

    Huang, Chao-Song; Retterer, J. M.; Beaujardiere, O. De La; Roddy, P. A.; Hunton, D.E.; Ballenthin, J. O.; Pfaff, Robert F.

    2012-01-01

    Broad plasma depletions in the equatorial ionosphere near dawn are region in which the plasma density is reduced by 1-3 orders of magnitude over thousands of kilometers in longitude. This phenomenon is observed repeatedly by the Communication/Navigation Outage Forecasting System (C/NOFS) satellite during deep solar minimum. The plasma flow inside the depletion region can be strongly upward. The possible causal mechanism for the formation of broad plasma depletions is that the broad depletions result from merging of multiple equatorial plasma bubbles. The purpose of this study is to demonstrate the feasibility of the merging mechanism with new observations and simulations. We present C/NOFS observations for two cases. A series of plasma bubbles is first detected by C/NOFS over a longitudinal range of 3300-3800 km around midnight. Each of the individual bubbles has a typical width of approx 100 km in longitude, and the upward ion drift velocity inside the bubbles is 200-400 m/s. The plasma bubbles rotate with the Earth to the dawn sector and become broad plasma depletions. The observations clearly show the evolution from multiple plasma bubbles to broad depletions. Large upward plasma flow occurs inside the depletion region over 3800 km in longitude and exists for approx 5 h. We also present the numerical simulations of bubble merging with the physics-based low-latitude ionospheric model. It is found that two separate plasma bubbles join together and form a single, wider bubble. The simulations show that the merging process of plasma bubbles can indeed occur in incompressible ionospheric plasma. The simulation results support the merging mechanism for the formation of broad plasma depletions.

  20. Cutoff effects of electron velocity distribution to the properties of plasma parameters near the plasma-sheath boundary

    International Nuclear Information System (INIS)

    Jelic, N.

    2011-01-01

    The plasma properties under high thermodynamic non-equilibrium condition, established due to the presence of electrically biased electrode, are investigated. Assumption of electron cut-off velocity distribution function (VDF), as done by Andrews and Varey in their investigations of the sheath region [J. Phys. A 3, 413 (1970)], has been extended here to both plasma and sheath regions. Analytic expressions for the moments of electron VDF, as well as for the electron screening temperature function dependence on the plasma-sheath local potential are derived. In deriving the ion velocity distribution the ''standard'' assumption of strict plasma quasineutrality, or equivalently vanishing of the plasma Debye length, is employed, whereas the ions are assumed to be generated at rest over the plasma region. However, unlike the standard approach of solving the plasma equation, where pure Boltzmann electron density profile is used, here we employ modified Boltzmann's electron density profile, due to cutoff effect of the electron velocity distribution. It is shown that under these conditions the quasineutrality equation solution is characterised by the electric field singularity for any negative value of the electrode bias potential as measured with respect to the plasma potential. The point of singularity i.e., the plasma length and its dependence on the electrode bias and sheath potential is established for the particular case of ionization profile mechanism proportional to the local electron density. Relevant parameters for the kinetic Bohm criterion are explicitly calculated for both ions and electrons, for arbitrary electrode bias.

  1. Relationship between plasma and tissue parameters of leucine metabolism

    International Nuclear Information System (INIS)

    Vazquez, J.A.; Paul, H.S.; Adibi, S.A.

    1986-01-01

    Using a primed continuous infusion of [1- 14 C] leucine, the authors investigated parameters of leucine metabolism in plasma, expired air, and tissues of fed and 48-hour starved rats. The ratios of muscle/plasma specific activity of α-ketoisocaproate (KIC) in fed and starved rats, respectively were not significantly different from one (1.07 +/- 0.14 and 0.97 +/- 0.10, mean +/- SE, 7 rats). The ratio of muscle/plasma specific activity of leucine was also not significantly different from one (0.86 +/- 0.11) in fed rats, but was significantly lower than one (0.80 +/- 0.07) in starved rats. The rate of leucine oxidation was approximately 32% higher when calculated based on plasma KIC rather than leucine specific activity. However, starvation significantly increased the rate of leucine oxidation with either specific activity. The rate of leucine incorporation into whole body protein was unaffected by starvation (32.7 +/- 3.5 vs 36.1 +/- 2.5 μmol/100 g/h), but the incorporation into total protein of liver (1350 +/- 140 vs 780 +/- 33 nmol) and of skeletal muscle (1940 +/- 220 vs 820 +/- 60 nmol) was significantly decreased. The authors conclude that a) leucine or KIC specific activity in muscle is better predicted by plasma KIC than leucine specific activity, and b) the tracer infusion technique is valid for the study of leucine oxidation but not for leucine incorporation into whole body protein

  2. Association of Irisin Plasma Levels with Anthropometric Parameters in Children with Underweight, Normal Weight, Overweight, and Obesity

    Directory of Open Access Journals (Sweden)

    Leticia Elizondo-Montemayor

    2017-01-01

    Full Text Available The correlations between irisin levels, physical activity, and anthropometric measurements have been extensively described in adults with considerable controversy, but little evidence about these relationships has been found in children. The objective of this study is to correlate the plasma levels of irisin in underweight, normal weight, overweight, and obese children with anthropometric parameters and physical activity levels. A cross-sample of 40 children was divided into the following groups on the basis of body mass index (BMI percentile. The correlations of plasma irisin levels with physical activity, anthropometric, and metabolic measurements were determined. Plasma irisin levels (ng/mL were lower for the underweight group (164.2 ± 5.95 than for the normal weight and obese groups (182.8 ± 5.58; p<0.05. Irisin levels correlated positively with BMI percentile (0.387, waist circumference (0.373, and fat-free mass (0.353; p<0.05, but not with body muscle mass (−0.027. After a multiple linear regression analysis, only BMI percentile (0.564; p<0.008 showed a positive correlation with irisin. Our results indicated no association with metabolic parameters. A negative correlation with physical activity was observed. Interrelationships among body components might influence irisin levels in children.

  3. Observation of plasma hole in a rotating plasma

    International Nuclear Information System (INIS)

    Nagaoka, Kenichi; Ishihara, Tatsuzo; Okamoto, Atsushi; Yoshimura, Shinji; Tanaka, Masayoshi Y.

    2001-01-01

    Plasma hole, a cylindrical density cavity, formed in a rotating plasma has been investigated experimentally. The plasma hole is characterized by large aspect ratio (length/radius ≥ 30), steep boundary layer between the hole and the ambient plasma (10 ion Larmor radius), and extremely high positive potential (130 V). The flow velocity field associated with plasma hole structure has been measured, and is found to have interesting features: (1) plasma rotates in azimuthal direction at a maximum velocity of order of ion sound speed, (2) plasma flows radially inward across the magnetic field line, (3) there present an axial flow reversal between core and peripheral region. It is found that the flow pattern of the plasma hole is very similar to the that of well-developed typhoon with core. (author)

  4. Relationship between Lipids Levels of Serum and Seminal Plasma and Semen Parameters in 631 Chinese Subfertile Men.

    Directory of Open Access Journals (Sweden)

    Jin-Chun Lu

    Full Text Available This prospective study was designed to investigate the relationship between lipids levels in both serum and seminal plasma and semen parameters.631 subfertile men were enrolled. Their obesity-associated markers were measured, and semen parameters were analyzed. Also, seminal plasma and serum TC, TG, HDL and LDL and serum FFA, FSH, LH, total testosterone (TT, estradiol (E2 and SHBG levels were detected.Seminal plasma and serum TG, TC and LDL levels were positively related to age. Serum TC, TG and LDL were positively related to obesity-associated markers (P < 0.001, while only seminal plasma TG was positively related to them (P < 0.05. For lipids levels in serum and seminal plasma, only TG level had slightly positive correlation between them (r = 0.081, P = 0.042. There was no significant correlation between serum lipids levels and semen parameters. However, seminal plasma TG, TC, LDL and HDL levels were negatively related to one or several semen parameters, including semen volume (SV, sperm concentration (SC, total sperm count (TSC, sperm motility, progressive motility (PR and total normal-progressively motile sperm counts (TNPMS. Moreover, seminal plasma TG, TC, LDL and HDL levels in patients with oligospermatism, asthenospermia and teratozoospermia were higher than those with normal sperm concentration, motility or morphology. After adjusting age and serum LH, FSH, TT, E2 and SHBG levels, linear regression analysis showed that SV was still significantly correlated with seminal plasma LDL (P = 0.012, both of SC and TSC with seminal plasma HDL (P = 0.028 and 0.002, and both of PR and sperm motility with seminal plasma TC (P = 0.012 and 0.051.The abnormal metabolism of lipids in male reproductive system may contribute to male factor infertility.

  5. Scaling study of edge plasma parameters using a multi-device database

    International Nuclear Information System (INIS)

    Tsui, H.Y.W.; Miner, W.H.; Wootton, A.J.

    1995-01-01

    A database consisting of edge equilibrium, turbulence and transport related plasma parameters has been compiled. Scaling laws for edge density, electron temperature, and radial particle flux are derived in an initial study using a subset of data obtained from tokamaks Phaedrus-T, Tokamak de Varennes, TEXT and TEXT-U. A comparison of edge particle transport in divertor and limiter plasmas shows that the magnetic topology of a separatrix or a divertor improves particle confinement. The particle diffusion coefficient varies radially in a manner opposite to that of Bohm diffusion. ((orig.))

  6. Magnetospheric plasma waves

    International Nuclear Information System (INIS)

    Shawhan, S.D.

    1977-01-01

    A brief history of plasma wave observations in the Earth's magnetosphere is recounted and a classification of the identified plasma wave phenomena is presented. The existence of plasma waves is discussed in terms of the characteristic frequencies of the plasma, the energetic particle populations and the proposed generation mechanisms. Examples are given for which plasmas waves have provided information about the plasma parameters and particle characteristics once a reasonable theory has been developed. Observational evidence and arguments by analogy to the observed Earth plasma wave processes are used to identify plasma waves that may be significant in other planetary magnetospheres. The similarities between the observed characteristics of the terrestrial kilometric radiation and radio bursts from Jupiter, Saturn and possibly Uranus are stressed. Important scientific problems concerning plasma wave processes in the solar system and beyond are identified and discussed. Models for solar flares, flare star radio outbursts and pulsars include elements which are also common to the models for magnetospheric radio bursts. Finally, a listing of the research and development in terms of instruments, missions, laboratory experiments, theory and computer simulations needed to make meaningful progress on the outstanding scientific problems of plasma wave research is given. (Auth.)

  7. Study of the transport parameters of cloud lightning plasmas

    International Nuclear Information System (INIS)

    Chang, Z. S.; Yuan, P.; Zhao, N.

    2010-01-01

    Three spectra of cloud lightning have been acquired in Tibet (China) using a slitless grating spectrograph. The electrical conductivity, the electron thermal conductivity, and the electron thermal diffusivity of the cloud lightning, for the first time, are calculated by applying the transport theory of air plasma. In addition, we investigate the change behaviors of parameters (the temperature, the electron density, the electrical conductivity, the electron thermal conductivity, and the electron thermal diffusivity) in one of the cloud lightning channels. The result shows that these parameters decrease slightly along developing direction of the cloud lightning channel. Moreover, they represent similar sudden change behavior in tortuous positions and the branch of the cloud lightning channel.

  8. Solar wind plasma periodicities observed at 1 AU by IMP 8

    Science.gov (United States)

    Paularena, K. I.; Szabo, A.; Lazarus, A. J.

    1995-01-01

    The IMP 8 spacecraft has been in Earth orbit since 1973, gathering plasma data over one complete 22-year solar cycle. These data are being examined to look for periodicities at time scales ranging from several hours to the entire span of the data set. A 1.3-year periodicity in the radial speed observed by IMP 8 and Voyager 2 has already been reported for the years from 1987 to 1993. The periodogram method, useful for unevenly sampled data such as the IMP 8 plasma data, has been used to search for other periods. It is interesting to note that the 13-year period is not present in the out-of-the-ecliptic component of the velocity (Vz), although a 1-year period is very obvious both visually and on the periodogram. Both components show a very strong peak associated with the 11-year solar cycle variation. This work will be extended to the thermal speed (a measure of the wind's temperature) and density, although the frequent correlations between these parameters and the velocity are expected to cause similar results. Additionally, the fine resolution data will be examined for shorter time periods than are visible using the hourly average data which are appropriate for longer periods. A comparison with periods observed at other spacecraft may also be made.

  9. Stationary neoclassical profiles of plasma parameters in stellarators

    International Nuclear Information System (INIS)

    Danilkin, I.S.; Mineev, A.B.

    1991-01-01

    Peculiarities of neoclassical model of heat and particle transfer, occuring by calculations of plasma stationary profile parameters in stellarators are considered. The main peculiarity out of all consists in ineadequate compatibility with real physical conditions on the boundary, requiring application of supplementary 'anomalous' transfer or special (but technically possible) adjustment of particle and heat sources to achieve solution in form of 'correct' monotonically sloping profile. It is stated, that neoclassical theory does not provide for well-known ambiguity of solutions for ambipolar electrical field by search of monotonous stationary profiles supported by outside sources

  10. Kalman filter data assimilation: targeting observations and parameter estimation.

    Science.gov (United States)

    Bellsky, Thomas; Kostelich, Eric J; Mahalov, Alex

    2014-06-01

    This paper studies the effect of targeted observations on state and parameter estimates determined with Kalman filter data assimilation (DA) techniques. We first provide an analytical result demonstrating that targeting observations within the Kalman filter for a linear model can significantly reduce state estimation error as opposed to fixed or randomly located observations. We next conduct observing system simulation experiments for a chaotic model of meteorological interest, where we demonstrate that the local ensemble transform Kalman filter (LETKF) with targeted observations based on largest ensemble variance is skillful in providing more accurate state estimates than the LETKF with randomly located observations. Additionally, we find that a hybrid ensemble Kalman filter parameter estimation method accurately updates model parameters within the targeted observation context to further improve state estimation.

  11. Kalman filter data assimilation: Targeting observations and parameter estimation

    International Nuclear Information System (INIS)

    Bellsky, Thomas; Kostelich, Eric J.; Mahalov, Alex

    2014-01-01

    This paper studies the effect of targeted observations on state and parameter estimates determined with Kalman filter data assimilation (DA) techniques. We first provide an analytical result demonstrating that targeting observations within the Kalman filter for a linear model can significantly reduce state estimation error as opposed to fixed or randomly located observations. We next conduct observing system simulation experiments for a chaotic model of meteorological interest, where we demonstrate that the local ensemble transform Kalman filter (LETKF) with targeted observations based on largest ensemble variance is skillful in providing more accurate state estimates than the LETKF with randomly located observations. Additionally, we find that a hybrid ensemble Kalman filter parameter estimation method accurately updates model parameters within the targeted observation context to further improve state estimation

  12. Multi-wavelength imaging observations of plasma depletions over Kavalur, India

    Directory of Open Access Journals (Sweden)

    H. S. S. Sinha

    2001-09-01

    Full Text Available Observations of ionospheric plasma depletions were made over Kavalur (12.56° N, 78.8° E, Mag. Lat 4.6° N, India during March–pril 1998 using an all sky optical imaging system operating at 630 nm, 777.4 nm and 557.7 nm. Out of 14 nights of observations, plasma depletions were seen only on 9 nights. Except for 21 March 1998, which was a magnetically disturbed period, all other nights belonged to a magnetically quiet period. Some of the important results obtained from these observations are: (a After the onset of the equatorial spread F (ESF, plasma depletions take typically about 2 hrs 40 min to come to a fully developed state, (b There are three distinct types of plasma depletions: type 1 have an east-west (e–w extent of 250–350 km with an inter-depletion distance (IDD of 125–300 km; Type 2 have an e–w extent of 100–150 km and IDD of 50–150 km; Type 3 have smallest the e–w extent (40–100 km and IDD of 20–60 km, (c Most of the observed plasma depletions (> 82% had their eastward velocity in the range of 25–125 ms–1. Almost stationary plasma depletions (0–25 ms–1 were observed on one night, which was magnetically disturbed. These very slow moving depletions appear to be the result of a modification of the F-region dynamo field due to direct penetration of the electric field and/or changes in the neutral winds induced by the magnetic disturbance, (d On the night of 21/22 March 1998, which was a magnetically disturbed period, plasma depletions could be seen simultaneously in all three observing wavelengths, i.e. in 630 nm, 777.4 nm and 557.7 nm. It is believed that this simultaneous occurrence was due to neutral density modifications as a result of enhanced magnetic activity. (e Well developed brightness patterns were observed for the first time in 777.4 nm images. Earlier, such brightness patterns were observed only in 630 nm and 557.7 nm images. These brightness patterns initially appear as very small regions in the

  13. Langmuir probe-based observables for plasma-turbulence code validation and application to the TORPEX basic plasma physics experiment

    International Nuclear Information System (INIS)

    Ricci, Paolo; Theiler, C.; Fasoli, A.; Furno, I.; Labit, B.; Mueller, S. H.; Podesta, M.; Poli, F. M.

    2009-01-01

    The methodology for plasma-turbulence code validation is discussed, with focus on the quantities to use for the simulation-experiment comparison, i.e., the validation observables, and application to the TORPEX basic plasma physics experiment [A. Fasoli et al., Phys. Plasmas 13, 055902 (2006)]. The considered validation observables are deduced from Langmuir probe measurements and are ordered into a primacy hierarchy, according to the number of model assumptions and to the combinations of measurements needed to form each of them. The lowest levels of the primacy hierarchy correspond to observables that require the lowest number of model assumptions and measurement combinations, such as the statistical and spectral properties of the ion saturation current time trace, while at the highest levels, quantities such as particle transport are considered. The comparison of the observables at the lowest levels in the hierarchy is more stringent than at the highest levels. Examples of the use of the proposed observables are applied to a specific TORPEX plasma configuration characterized by interchange-driven turbulence.

  14. Hot plasma parameters in Neptune's magnetosphere

    International Nuclear Information System (INIS)

    Krimigis, S.M.; Mauk, B.H.; Cheng, A.F.; Keath, E.P.; Kane, M.; Armstrong, T.P.; Gloeckler, G.; Lanzerotti, L.J.

    1990-01-01

    Energy spectra of energetic protons and electrons (E p approx-gt 28 keV, E e approx-gt 22 keV, respectively) obtained with the Low Energy Charged Particle (LECP) instrument during the Voyager 2 encounter with Neptune on August 24-25, 1989 are presented. The proton spectral form was a power law (dj/dE = KE -γ ), outside the orbit of Triton (∼14.3 R N ); inside that distance, it was found to be a hot (kT ≅ 60 keV) Maxwellian distribution. Such distributions, observed in other planets as well, have yet to be explained theoretically. Similarly, the electron spectral form changed from a simple power law outside Triton to a two-slope power law with a high energy tail inside. Intensity and spectral features in both proton and electron fluxes were identified in association with the crossings of the Triton and 1989 N1 L-shells, but these features do not occur simultaneously in both species. Such signatures were manifested by relative peaks in both kT and γ spectral indices. Peak proton pressures of ∼2x10 -9 dynes cm -2 , and β ∼ 0.2 were measured at successive magnetic equatorial crossings, both inbound and outbound. These parameters show Neptune's magnetosphere to be relatively undistorted by hot plasma loading, similar to that of Uranus and unlike those of Saturn and Jupiter. Trapped electron fluxes at Neptune, as at Uranus, exceed the whistler mode stably trapped flux limit. Whistler-induced pitch angle scattering of energetic electrons in the radiation belts can yield a precipitating energy flux sufficient to drive Neptune's aurora

  15. Magnetosheath plasma stability and ULF wave occurrence as a function of location in the magnetosheath and upstream bow shock parameters

    Science.gov (United States)

    Soucek, Jan; Escoubet, C. Philippe; Grison, Benjamin

    2015-04-01

    We present the results of a statistical study of the distribution of mirror and Alfvén-ion cyclotron (AIC) waves in the magnetosheath together with plasma parameters important for the stability of ULF waves, specifically ion temperature anisotropy and ion beta. Magnetosheath crossings registered by Cluster spacecraft over the course of 2 years served as a basis for the statistics. For each observation we used bow shock, magnetopause, and magnetosheath flow models to identify the relative position of the spacecraft with respect to magnetosheath boundaries and local properties of the upstream shock crossing. A strong dependence of both plasma parameters and mirror/AIC wave occurrence on upstream ΘBn and MA is identified. We analyzed a joint dependence of the same parameters on ΘBn and fractional distance between shock and magnetopause, zenith angle, and length of the flow line. Finally, the occurrence of mirror and AIC modes was compared against the respective instability thresholds. We noted that AIC waves occurred nearly exclusively under mirror stable conditions. This is interpreted in terms of different characters of nonlinear saturation of the two modes.

  16. Temporal evolution of the spectral lines emission and temperatures in laser induced plasmas through characteristic parameters

    International Nuclear Information System (INIS)

    Bredice, F.; Pacheco Martinez, P.; Sánchez-Aké, C.; Villagrán-Muniz, M.

    2015-01-01

    . The plasma was produced in vacuum and was observed at different distances from the target. A good agreement between the temperature calculated by the traditional Boltzmann plot and by this method was obtained. - Highlights: • The time evolution of the spectral lines for each point of the plasma can be expressed by a reduced set of constants B i  and δ i . • These constants can be used as a criterion for line selection in LIBS and the evaluation of the LTE departure of the plasma. • It is possible to check if any spectral lines are useful for Boltzmann analysis or if they have been properly classified. • The temperature evolution for each point of the plasma depends on its initial temperature T(t 0 ) and the constants B i . • The determination of these constants does not depend on any parameters which are time-independent

  17. Optimization of the plasma parameters for the high current and uniform large-scale pulse arc ion source of the VEST-NBI system

    International Nuclear Information System (INIS)

    Jung, Bongki; Park, Min; Heo, Sung Ryul; Kim, Tae-Seong; Jeong, Seung Ho; Chang, Doo-Hee; Lee, Kwang Won; In, Sang-Ryul

    2016-01-01

    Highlights: • High power magnetic bucket-type arc plasma source for the VEST NBI system is developed with modifications based on the prototype plasma source for KSTAR. • Plasma parameters in pulse duration are measured to characterize the plasma source. • High plasma density and good uniformity is achieved at the low operating pressure below 1 Pa. • Required ion beam current density is confirmed by analysis of plasma parameters and results of a particle balance model. - Abstract: A large-scale hydrogen arc plasma source was developed at the Korea Atomic Energy Research Institute for a high power pulsed NBI system of VEST which is a compact spherical tokamak at Seoul national university. One of the research target of VEST is to study innovative tokamak operating scenarios. For this purpose, high current density and uniform large-scale pulse plasma source is required to satisfy the target ion beam power efficiently. Therefore, optimizing the plasma parameters of the ion source such as the electron density, temperature, and plasma uniformity is conducted by changing the operating conditions of the plasma source. Furthermore, ion species of the hydrogen plasma source are analyzed using a particle balance model to increase the monatomic fraction which is another essential parameter for increasing the ion beam current density. Conclusively, efficient operating conditions are presented from the results of the optimized plasma parameters and the extractable ion beam current is calculated.

  18. Production of a hot ion plasma at the lower hybrid resonance and measurement of its parameters

    International Nuclear Information System (INIS)

    Glagolev, V.M.; Dyubajlov, A.G.; Krivov, N.A.; Martynenko, V.V.; Skosyrev, Yu.V.

    1975-01-01

    Electromagnetic fields delayed along a magnetic field have been created within a plasma with the aid of a coil encircling the plasma column. When these waves were propagated transversely in relation to the magnetic field in a plasma with density rising along its radius, they were delayed in the direction of propagation. The amplitude and phase distributions of the electromagentic fields along the radius of the plasma column were measured at different moments in time. The existence of an absorption band of these waves within the plasma was detected. The absorption band was shifted towards the outer boundary from the plasma when plasma density was increased. By four independent methods it was established that the gas-kinetic pressure of the plasma, measured according to its diamagnetism, is determined by the ion component. It was found that the energy of electrons at right angles to the magnetic field is considerably less than that of the ions. The cause of limited heating was an increase in density and energy losses in the charge-exchange process. In order to improve vacuum conditions, the coil around the plasma was placed in a metallic chamber, and the UHF plasma source used in the original experiments was replaced by a hydride-film source. This made it possible to increase the internal energy of the plasma to 3x10 15 eV cm -3 at a density of (1-3)x10 12 cm -3 . The mean energy of atoms leaving the plasma at right angles to the magnetic field as a result of charge exchange reached 1 keV. The region of change in plasma parameters (density and magnetic field) for which heating was observed corresponded to the linear transformation theory. Non-linear effects could occur only in the first stage of heating, when the electric fields were strong, but plasma temperature was low. Heating efficiency was measured by a reflectometer installed in the coaxial line connecting the generator and the HF input coil to the plasma. The measurements showed that about 20% of the power

  19. Observation of bifurcation phenomena in an electron beam plasma system

    International Nuclear Information System (INIS)

    Hayashi, N.; Tanaka, M.; Shinohara, S.; Kawai, Y.

    1995-01-01

    When an electron beam is injected into a plasma, unstable waves are excited spontaneously near the electron plasma frequency f pe by the electron beam plasma instability. The experiment on subharmonics in an electron beam plasma system was performed with a glow discharge tube. The bifurcation of unstable waves with the electron plasma frequency f pe and 1/2 f pe was observed using a double-plasma device. Furthermore, the period doubling route to chaos around the ion plasma frequency in an electron beam plasma system was reported. However, the physical mechanism of bifurcation phenomena in an electron beam plasma system has not been clarified so far. We have studied nonlinear behaviors of the electron beam plasma instability. It was found that there are some cases: the fundamental unstable waves and subharmonics of 2 period are excited by the electron beam plasma instability, the fundamental unstable waves and subharmonics of 3 period are excited. In this paper, we measured the energy distribution functions of electrons and the dispersion relation of test waves in order to examine the physical mechanism of bifurcation phenomena in an electron beam plasma system

  20. Eddy turbulence parameters inferred from radar observations at Jicamarca

    Directory of Open Access Journals (Sweden)

    M. N. Vlasov

    2007-03-01

    Full Text Available Significant electron density striations, neutral temperatures 27 K above nominal, and intense wind shear were observed in the E-region ionosphere over the Jicamarca Radio Observatory during an unusual event on 26 July 2005 (Hysell et al., 2007. In this paper, these results are used to estimate eddy turbulence parameters and their effects. Models for the thermal balance in the mesosphere/lower thermosphere and the charged particle density in the E region are developed here. The thermal balance model includes eddy conduction and viscous dissipation of turbulent energy as well as cooling by infrared radiation. The production and recombination of ions and electrons in the E region, together with the production and transport of nitric oxide, are included in the plasma density model. Good agreement between the model results and the experimental data is obtained for an eddy diffusion coefficient of about 1×103 m2/s at its peak, which occurs at an altitude of 107 km. This eddy turbulence results in a local maximum of the temperature in the upper mesosphere/lower thermosphere and could correspond either to an unusually high mesopause or to a double mesosphere. Although complicated by plasma dynamic effects and ongoing controversy, our interpretation of Farley-Buneman wave phase velocity (Hysell et al., 2007 is consistent with a low Brunt-Väisälä frequency in the region of interest. Nitric oxide transport due to eddy diffusion from the lower thermosphere to the mesosphere causes electron density changes in the E region whereas NO density modulation due to irregularities in the eddy diffusion coefficient creates variability in the electron density.

  1. Eddy turbulence parameters inferred from radar observations at Jicamarca

    Directory of Open Access Journals (Sweden)

    M. N. Vlasov

    2007-03-01

    Full Text Available Significant electron density striations, neutral temperatures 27 K above nominal, and intense wind shear were observed in the E-region ionosphere over the Jicamarca Radio Observatory during an unusual event on 26 July 2005 (Hysell et al., 2007. In this paper, these results are used to estimate eddy turbulence parameters and their effects. Models for the thermal balance in the mesosphere/lower thermosphere and the charged particle density in the E region are developed here. The thermal balance model includes eddy conduction and viscous dissipation of turbulent energy as well as cooling by infrared radiation. The production and recombination of ions and electrons in the E region, together with the production and transport of nitric oxide, are included in the plasma density model. Good agreement between the model results and the experimental data is obtained for an eddy diffusion coefficient of about 1×103 m2/s at its peak, which occurs at an altitude of 107 km. This eddy turbulence results in a local maximum of the temperature in the upper mesosphere/lower thermosphere and could correspond either to an unusually high mesopause or to a double mesosphere. Although complicated by plasma dynamic effects and ongoing controversy, our interpretation of Farley-Buneman wave phase velocity (Hysell et al., 2007 is consistent with a low Brunt-Väisälä frequency in the region of interest. Nitric oxide transport due to eddy diffusion from the lower thermosphere to the mesosphere causes electron density changes in the E region whereas NO density modulation due to irregularities in the eddy diffusion coefficient creates variability in the electron density.

  2. Ion acoustic waves and related plasma observations in the solar wind

    International Nuclear Information System (INIS)

    Gurnett, D.A.; Marsch, E.; Pilipp, W.; Schwenn, R.; Rosenbauer, H.

    1979-01-01

    This paper presents an investigation of solar wind ion acoustic waves and their relationship to the macroscopic and microscopic characteristics of the solar wind plasma. Comparisons with the overall solar wind corotational structure show that the most intense ion acoustic waves usually occur in the low-velocity regions ahead of high-speed solar wind streams. Of the detailed plasma parameters investigated, the ion acoustic wave intensities are found to be most closely correlated with the electron to proton temperature ratio T/sub e//T/sub p/ and with the electron heat flux. Investigations of the detailed electron and proton distribution functions also show that the ion acoustic waves usually occur in regions with highly non-Maxwellian distributions characteristic of double-proton streams. The distribution functions for the double-proton streams are usually not resolved into two clearly defined peaks, but rather they appear as a broad shoulder on the main proton distribution. Two main mechanisms, an electron heat flux instability and a double-ion beam instability, are considered for generating the ion-acoustic-like waves observed in the solar wind. Both mechanisms have favorable and unfavorable features. The electron heat flux mechanism can account for the observed waves at moderate to large ratios of T/sub e//T/sub p/ but has problems when T/sub e//T/sub p/ is small, as sometimes occurs. The ion beam instability appears to provide more flexibility on the T/sub e//T/sub p/ ratio; however detailed comparisons using observed distribution functions indicate that the ion beam mode is usually stable. Possible resolutions of these difficulties are discussed

  3. Ulysses radio and plasma wave observations in the jupiter environment.

    Science.gov (United States)

    Stone, R G; Pedersen, B M; Harvey, C C; Canu, P; Cornilleau-Wehrlin, N; Desch, M D; de Villedary, C; Fainberg, J; Farrell, W M; Goetz, K; Hess, R A; Hoang, S; Kaiser, M L; Kellogg, P J; Lecacheux, A; Lin, N; Macdowall, R J; Manning, R; Meetre, C A; Meyer-Vernet, N; Moncuquet, M; Osherovich, V; Reiner, M J; Tekle, A; Thiessen, J; Zarka, P

    1992-09-11

    The Unified Radio and Plasma Wave (URAP) experiment has produced new observations of the Jupiter environment, owing to the unique capabilities of the instrument and the traversal of high Jovian latitudes. Broad-band continuum radio emission from Jupiter and in situ plasma waves have proved valuable in delineating the magnetospheric boundaries. Simultaneous measurements of electric and magnetic wave fields have yielded new evidence of whistler-mode radiation within the magnetosphere. Observations of aurorallike hiss provided evidence of a Jovian cusp. The source direction and polarization capabilities of URAP have demonstrated that the outer region of the lo plasma torus supported at least five separate radio sources that reoccurred during successive rotations with a measurable corotation lag. Thermal noise measurements of the lo torus densities yielded values in the densest portion that are similar to models suggested on the basis of Voyager observations of 13 years ago. The URAP measurements also suggest complex beaming and polarization characteristics of Jovian radio components. In addition, a new class of kilometer-wavelength striated Jovian bursts has been observed.

  4. Observation of plasma motion in a coaxial plasma opening switch with a chordal laser interferometer

    International Nuclear Information System (INIS)

    Teramoto, Y.; Urakami, H.; Akiyama, H.; Kohno, S.; Katsuki, S.

    2002-01-01

    Electron densities in a coaxial plasma opening switch were measured at many lines-of-slight. In the present experiment, electron density was measured by a He-Ne laser interferometer with chordal lines-of sight. In order to observe the motion of the POS plasma, the electron density contours during the conduction, opening and post-opening phases were drawn by combining the results of interferometer experiments. The radial and axial motion of POS plasma was investigated from the density contours. As conduction time progressed, the POS plasma moved toward downstream. At 800 ns, which corresponds to the time of opening in the current waveform, low-density region less than 10 15 cm -2 is seen at 10 mm from the cathode. After the opening was completed, the low-density gap disappeared and the shape of the corn-shape-like plasma was distorted. (author)

  5. Latest Observations of Interstellar Plasma Waves, Radio Emissions, and Dust Impacts from the Voyager 1 Plasma Wave Instrument

    Science.gov (United States)

    Gurnett, D. A.

    2017-12-01

    Voyager 1, which is now 140 AU (Astronomical Units) from the Sun, crossed the heliopause into interstellar space in 2012 at a heliospheric radial distance of 121 AU. Since crossing the heliopause the plasma wave instrument has on several occasions detected plasma oscillations and radio emissions at or near the electron plasma frequency. The most notable of these events occurred in Oct.-Nov. 2012, April-May 2013, Feb.-Nov. 2014, and Sept.-Nov. 2015. Most recently, a very weak emission has been observed at or near the electron plasma frequency through most of 2016. These emissions are all believed to be produced by shock waves propagating into the interstellar medium from energetic solar events. The oscillation frequency of the plasma indicates that the electron density in the interstellar plasma has gradually increased from about 0.06 cm-3 near the heliopause to about 0.12 cm-3 in the most recent data. The plasma wave instrument also continues to detect impacts of what are believed to be interstellar dust grains at an impact rate of a few per year. Comparisons with Ulysses observations of similar interstellar dust near 5 AU suggest that the dust grains have sizes in the range from about 0.1 to 1 micrometer. Although the statistics are poor due to the low count rate, the dust flux observed in the outer heliosphere appears to be as much as a factor of two greater than that observed in the interstellar medium. Since the dust particles are likely to be charged, this increase in the heliosphere suggests that there may be a significant electrodynamic interaction of the dust particles with the heliospheric magnetic field.

  6. Long-time integrator for the study on plasma parameter fluctuations

    International Nuclear Information System (INIS)

    Zalkind, V.M.; Tarasenko, V.P.

    1975-01-01

    A device measuring the absolute value (x) of a fluctuating quantity x(t) averaged over a large number of realizations is described. The specific features of the device are the use of the time selector (Δ t = 50 μs - 1 ms) and the large time integration constant (tau = 30 hrs). The device is meant for studying fluctuations of parameters of a pulse plasma with a small repetition frequency

  7. Observation of plasma toroidal-momentum dissipation by neoclassical toroidal viscosity.

    Science.gov (United States)

    Zhu, W; Sabbagh, S A; Bell, R E; Bialek, J M; Bell, M G; LeBlanc, B P; Kaye, S M; Levinton, F M; Menard, J E; Shaing, K C; Sontag, A C; Yuh, H

    2006-06-09

    Dissipation of plasma toroidal angular momentum is observed in the National Spherical Torus Experiment due to applied nonaxisymmetric magnetic fields and their plasma-induced increase by resonant field amplification and resistive wall mode destabilization. The measured decrease of the plasma toroidal angular momentum profile is compared to calculations of nonresonant drag torque based on the theory of neoclassical toroidal viscosity. Quantitative agreement between experiment and theory is found when the effect of toroidally trapped particles is included.

  8. Characterization of plasma parameters in shaped PBX-M discharges

    Science.gov (United States)

    England, A. C.; Bell, R. E.; Hirshman, S. P.; Kaita, R.; Kugel, H. W.; LeBlanc, B. L.; Lee, D. K.; Okabayashi, M.; Sun, Y.-C.; Takahashi, H.

    1997-09-01

    The Princeton Beta Experiment-Modification (PBX-M) was run both with elliptical and with bean-shaped plasmas during the 1992 and 1993 operating periods. Two deuterium-fed neutral beams were used for auxiliary heating, and during 1992 the average power was 0741-3335/39/9/008/img13. This will be referred to as the lower neutral-beam power (LNBP) period. As many as four deuterium-fed neutral beams were used during 1993, and the average power was 0741-3335/39/9/008/img14. This will be referred to as the medium neutral-beam power (MNBP) period. The neutron source strength, Sn, showed a scaling with injected power 0741-3335/39/9/008/img15, 0741-3335/39/9/008/img16 for both the LMBP and MNBP periods. A much wider range of shaping parameters was studied during the MNBP as compared with the LNBP period. A weak positive dependence on bean shaping was observed for the LNBP, and a stronger positive dependence on shaping was observed for MNBP, viz 0741-3335/39/9/008/img17. High values of Sn were obtained in bean-shaped plasmas for the highest values of 0741-3335/39/9/008/img18 at 0741-3335/39/9/008/img19 for the LNBP. For the MNBP the highest values of Sn and stored energy were obtained at 0741-3335/39/9/008/img19, and the highest values of 0741-3335/39/9/008/img18 were obtained at 0741-3335/39/9/008/img22. The achievement of high Sn is aided by high neutral-beam power, high toroidal field, strong shaping, high electron temperature, and broad profiles. The achievement of high 0741-3335/39/9/008/img18 is aided by low toroidal field, high density, less shaping, broad profiles, and access to the H-mode, viz 0741-3335/39/9/008/img24. The achievement of high 0741-3335/39/9/008/img25 is aided by strong shaping, high density, broad profiles, and access to the H-mode, viz 0741-3335/39/9/008/img26. Some comparisons with the previous higher neutral-beam (HNBP) period in 1989 are also made.

  9. Experimental observation of electron-temperature-gradient turbulence in a laboratory plasma.

    Science.gov (United States)

    Mattoo, S K; Singh, S K; Awasthi, L M; Singh, R; Kaw, P K

    2012-06-22

    We report the observation of electron-temperature-gradient (ETG) driven turbulence in the laboratory plasma of a large volume plasma device. The removal of unutilized primary ionizing and nonthermal electrons from uniform density plasma and the imposition and control of the gradient in the electron temperature (T[Symbol: see text] T(e)) are all achieved by placing a large (2 m diameter) magnetic electron energy filter in the middle of the device. In the dressed plasma, the observed ETG turbulence in the lower hybrid range of frequencies ν = (1-80 kHz) is characterized by a broadband with a power law. The mean wave number k perpendicular ρ(e) = (0.1-0.2) satisfies the condition k perpendicular ρ(e) ≤ 1, where ρ(e) is the electron Larmor radius.

  10. Fine structure of charge exchange lines observed in laboratory plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ida, K.; Nishimura, S. [National Inst. for Fusion Science, Nagoya (Japan); Kondo, K.

    1997-01-01

    The influence of the fine structure of charge exchange lines appears only at the plasma edge or in the recombining phase where the ion temperature is low enough. The observed spectra in Li III and C VI are consistent with the sum of fine-structure components populated by statistical weights (assuming complete l-mixing) not by direct charge exchange cross sections. Some discrepancy was observed in the intensity ratio of fine-structure components between the observation and calculation for C VI in the recombining phase. The fine-structure of charge exchange lines gives an apparent Doppler shift in plasma rotation velocity measurement using charge exchange spectroscopy. (author)

  11. Geomagnetically conjugate observation of plasma bubbles and thermospheric neutral winds at low latitudes

    Science.gov (United States)

    Fukushima, D.; Shiokawa, K.; Otsuka, Y.; Nishioka, M.; Kubota, M.; Tsugawa, T.; Nagatsuma, T.; Komonjinda, S.; Yatini, C. Y.

    2015-03-01

    This is the first paper that reports simultaneous observations of zonal drift of plasma bubbles and the thermospheric neutral winds at geomagnetically conjugate points in both hemispheres. The plasma bubbles were observed in the 630 nm nighttime airglow images taken by using highly sensitive all-sky airglow imagers at Kototabang, Indonesia (geomagnetic latitude (MLAT): 10.0°S), and Chiang Mai, Thailand (MLAT: 8.9°N), which are nearly geomagnetically conjugate stations, for 7 h from 13 to 20 UT (from 20 to 03 LT) on 5 April 2011. The bubbles continuously propagated eastward with velocities of 100-125 m/s. The 630 nm images at Chiang Mai and those mapped to the conjugate point of Kototabang fit very well, which indicates that the observed plasma bubbles were geomagnetically connected. The eastward thermospheric neutral winds measured by two Fabry-Perot interferometers were 70-130 m/s at Kototabang and 50-90 m/s at Chiang Mai. We compared the observed plasma bubble drift velocity with the velocity calculated from the observed neutral winds and the model conductivity, to investigate the F region dynamo contribution to the bubble drift velocity. The estimated drift velocities were 60-90% of the observed velocities of the plasma bubbles, suggesting that most of the plasma bubble velocity can be explained by the F region dynamo effect.

  12. Observation of plasma motion in a coaxial plasma opening switch with a chordal laser interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Teramoto, Y.; Urakami, H.; Akiyama, H. [Kumamoto Univ., Graduate School of Science and Technology, Kumamoto (Japan); Kohno, S. [Ariake National College of Technology, Dept. of Electrical Engineering, Fukuoka (Japan); Katsuki, S. [Kumamoto Univ., Dept. of Electrical and Computer Engineering, Kumamoto (Japan)

    2002-06-01

    Electron densities in a coaxial plasma opening switch were measured at many lines-of-slight. In the present experiment, electron density was measured by a He-Ne laser interferometer with chordal lines-of sight. In order to observe the motion of the POS plasma, the electron density contours during the conduction, opening and post-opening phases were drawn by combining the results of interferometer experiments. The radial and axial motion of POS plasma was investigated from the density contours. As conduction time progressed, the POS plasma moved toward downstream. At 800 ns, which corresponds to the time of opening in the current waveform, low-density region less than 10{sup 15} cm{sup -2} is seen at 10 mm from the cathode. After the opening was completed, the low-density gap disappeared and the shape of the corn-shape-like plasma was distorted. (author)

  13. DYNAMIC OF CHANGES OF BLOOD PLASMA ENERGY METABOLISM PARAMETERS IN SUCKLING COWS DURING CALVING INTERVAL

    Directory of Open Access Journals (Sweden)

    Ales Pavlik

    2015-02-01

    Full Text Available In this study, effect of environmental condition changes during gazing period on energy metabolism parameters was investigated. Totally 40 Aberdeen Angus cows were selected for observation. Calving all of cows was situated into March. The feeding ration for the animals was comprised by pasture during the grazing period and corn silage, hay and granulated distiller’s grains during the winter period. At average age 9 days before calving, and subsequently 10, 81, 151, 189 and 273 days after calving, blood was sampled and analysed for glucose and NEFA (non-esterified fatty acid concentrations on KONELAB T20xt automatic analyser (Thermo Fisher Scientific, Finland and currently available commercial kits (Biovendor-Laboratorni medicina, Czech Republic. A rapid increase (p < 0.05 of glucose concentration was detected in blood plasma of cows in period before calving to 81 days post partum. Average value of glucose concentration at 273 days postpartum was significant (p < 0.05 lower comparing to day 189. The highest concentrations of NEFA in blood plasma of cows were found at 10 day postpartum. After that, during the persisted higher temperature period the NEFA concentration decreased significantly (p < 0.01 till 189 days postpartum. At the end of monitored period concentration of NEFA in blood plasma significantly decreased (p < 0.05. Changes of hot and cold season during the grazing period probably according to forage quality and had significant effects on blood plasma NEFA and glucose concentrations.

  14. Lindhard's polarization parameter and atomic sum rules in the local plasma approximation

    DEFF Research Database (Denmark)

    Cabrera-Trujillo, R.; Apell, P.; Oddershede, J.

    2017-01-01

    In this work, we analyze the effects of Lindhard polarization parameter, χ, on the sum rule, Sp, within the local plasma approximation (LPA) as well as on the logarithmic sum rule Lp = dSp/dp, in both cases for the system in an initial excited state. We show results for a hydrogenic atom with nuc......In this work, we analyze the effects of Lindhard polarization parameter, χ, on the sum rule, Sp, within the local plasma approximation (LPA) as well as on the logarithmic sum rule Lp = dSp/dp, in both cases for the system in an initial excited state. We show results for a hydrogenic atom...... in terms of a screened charge Z* for the ground state. Our study shows that by increasing χ, the sum rule for p0 it increases, and the value p=0 provides the normalization/closure relation which remains fixed to the number of electrons for the same initial state. When p is fixed...

  15. Electron holes observed in the Moon Plasma Wake

    Science.gov (United States)

    Hutchinson, I. H.; Malaspina, D.; Zhou, C.

    2017-10-01

    Electrostatic instabilities are predicted in the magnetized wake of plasma flowing past a non-magnetic absorbing object such as a probe or the moon. Analysis of the data from the Artemis satellites, now orbiting the moon at distances ten moon radii and less, shows very clear evidence of fast-moving isolated solitary potential structures causing bipolar electric field excursions as they pass the satellite's probes. These structures have all the hallmarks of electron holes: BGK solitons typically a few Debye-lengths in size, self-sustaining by a deficit of phase-space density on trapped orbits. Electron holes are now observed to be widespread in space plasmas. They have been observed in PIC simulations of the moon wake to be the non-linear consequence of the predicted electron instabilities. Simulations document hole prevalence, speed, length, and depth; and theory can explain many of these features from kinetic analysis. The solar wind wake is certainly the cause of the overwhelming majority of the holes observed by Artemis, because we observe almost all holes to be in or very near to the wake. We compare theory and simulation of the hole generation, lifetime, and transport mechanisms with observations. Work partially supported by NASA Grant NNX16AG82G.

  16. Temporal evolution of the spectral lines emission and temperatures in laser induced plasmas through characteristic parameters

    Energy Technology Data Exchange (ETDEWEB)

    Bredice, F., E-mail: faustob@ciop.unlp.edu.ar [Centro de Investigaciones Ópticas, P.O. Box 3 C. P.1897 Gonnet, La Plata (Argentina); Pacheco Martinez, P. [Grupo de Espectroscopía Óptica de Emisión y Láser, Universidad del Atlántico, Barranquilla (Colombia); Sánchez-Aké, C.; Villagrán-Muniz, M. [Laboratorio de Fotofísica, Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Apartado Postal 70-186, México D.F. 04510 (Mexico)

    2015-05-01

    evolution of carbon lines obtained from a plasma generated by a Nd:YAG laser. The plasma was produced in vacuum and was observed at different distances from the target. A good agreement between the temperature calculated by the traditional Boltzmann plot and by this method was obtained. - Highlights: • The time evolution of the spectral lines for each point of the plasma can be expressed by a reduced set of constants B{sub i} and δ{sub i}. • These constants can be used as a criterion for line selection in LIBS and the evaluation of the LTE departure of the plasma. • It is possible to check if any spectral lines are useful for Boltzmann analysis or if they have been properly classified. • The temperature evolution for each point of the plasma depends on its initial temperature T(t{sub 0}) and the constants B{sub i}. • The determination of these constants does not depend on any parameters which are time-independent.

  17. Predicted and observed therapeutic dose exceedances of ionizable pharmaceuticals in fish plasma from urban coastal systems.

    Science.gov (United States)

    Scott, W Casan; Du, Bowen; Haddad, Samuel P; Breed, Christopher S; Saari, Gavin N; Kelly, Martin; Broach, Linda; Chambliss, C Kevin; Brooks, Bryan W

    2016-04-01

    Instream flows of the rapidly urbanizing watersheds and estuaries of the Gulf of Mexico in Texas (USA) are increasingly dominated by reclaimed waters. Though ionizable pharmaceuticals have received increasing attention in freshwaters, many research questions remain unanswered, particularly in tidally influenced urban coastal systems, which experience significant spatiotemporal variability in pH that influences bioavailability and bioaccumulation. The authors coupled fish plasma modeling of therapeutic hazard values with field monitoring of water chemistry variability and pharmaceutical occurrence to examine whether therapeutic hazards to fish existed within these urban coastal ecosystems and whether therapeutic hazards differed within and among coastal locations and seasons. Spatial and temporal fluctuations in pH within study sites altered the probability of encountering pharmaceutical hazards to fish. Significant water quality differences were consistently observed among traditional parameters and pharmaceuticals collected from surface and bottom waters, which are rarely sampled during routine surface water quality assessments. The authors then compared modeling predictions of fish plasma concentrations of pharmaceuticals to measured plasma levels from various field-collected fish species. Diphenhydramine and diltiazem were observed in plasma of multiple species, and diltiazem exceeded human therapeutic doses in largemouth bass, catfish, and mullet inhabiting these urban estuaries. Though the present study only examined a small number of target analytes, which represent a microcosm of the exposome of these fish, coastal systems are anticipated to be more strongly influenced by continued urbanization, altered instream flows, and population growth in the future. Unfortunately, aquatic toxicology information for diltiazem and many other pharmaceuticals is not available for marine and estuarine organisms, but such field observations suggest that potential adverse

  18. Plasma parameters, fluctuations and kinetics in a magnetic field line reconnection experiment

    International Nuclear Information System (INIS)

    Wild, N.C. Jr.

    1983-01-01

    The processes associated with reconnecting magnetic field lines have been studied in a large experimental laboratory plasma. Detailed time- and space-resolved probe measurements of the plasma density, temperature, potential and electric and magnetic fields are discussed. Plasma currents are seen to modify the vacuum magnetic field topology. A flat neutral sheet develops along the separatrix where magnetic flux is transferred from regions of private to common flux. Forced tearing and magnetic island formation are also observed. Rapid electron heating, density and temperature nonuniformities and plasma potential gradients are all observed. The pressure is found to peak at the two edges of the neutral sheet. The dissipation E.J is determined and analyzed in terms of particle heating and fluid acceleration. A consistent, detailed picture of the energy flow via Poynting's theorem is also described. Significant temporal fluctuations in the magnetic fields and electron velocity distribution are measured and seen to give rise to anomalously high values for the plasma resistivity, the ion viscosity and the cross-field thermal conductivity. Electron temperature fluctuations, double layers associated with partial current disruptions, and whistler wave magnetic turbulence have all been identified and studied during the course of the reconnection event

  19. Measurement of plasma parameters

    International Nuclear Information System (INIS)

    1999-01-01

    The physics issues of the measurements of the plasma properties necessary to provide both the control and science data for achieving the goals of the ITER device are discussed. The assessment of the requirements for these measurements is first discussed, together with priorities that relate to the experimental program. Subsequently, some of the proposed measurement techniques, the plasma diagnostics, are described with particular emphasis on their implementation on ITER and their capability to meet the requirements. A judgement on the present status of the diagnostic program on ITER is provided with some indication of the research and development program necessary to demonstrate viability of techniques or their implementation. (author)

  20. Helicon plasma ion temperature measurements and observed ion cyclotron heating in proto-MPEX

    Science.gov (United States)

    Beers, C. J.; Goulding, R. H.; Isler, R. C.; Martin, E. H.; Biewer, T. M.; Caneses, J. F.; Caughman, J. B. O.; Kafle, N.; Rapp, J.

    2018-01-01

    The Prototype-Material Plasma Exposure eXperiment (Proto-MPEX) linear plasma device is a test bed for exploring and developing plasma source concepts to be employed in the future steady-state linear device Material Plasma Exposure eXperiment (MPEX) that will study plasma-material interactions for the nuclear fusion program. The concept foresees using a helicon plasma source supplemented with electron and ion heating systems to reach necessary plasma conditions. In this paper, we discuss ion temperature measurements obtained from Doppler broadening of spectral lines from argon ion test particles. Plasmas produced with helicon heating alone have average ion temperatures downstream of the Helicon antenna in the range of 3 ± 1 eV; ion temperature increases to 10 ± 3 eV are observed with the addition of ion cyclotron heating (ICH). The temperatures are higher at the edge than the center of the plasma either with or without ICH. This type of profile is observed with electrons as well. A one-dimensional RF antenna model is used to show where heating of the plasma is expected.

  1. The LXCat project: Electron scattering cross sections and swarm parameters for low temperature plasma modeling

    International Nuclear Information System (INIS)

    Pancheshnyi, S.; Biagi, S.; Bordage, M.C.; Hagelaar, G.J.M.; Morgan, W.L.; Phelps, A.V.; Pitchford, L.C.

    2012-01-01

    Graphical abstract: LXCat is an open-access website containing data needed for low temperature plasma modeling as well as on-line tools useful for their manipulation. Highlights: ► LXCat: an open-access website with data for low temperature plasma modeling. ► Contains compilations of electron scattering cross sections and transport data. ► Data from different contributors for many neutral, ground-state species. ► On-line tools for browsing, plotting, up/downloading data. ► On-line Boltzmann solver for calculating electron swarm parameters. - Abstract: LXCat is a dynamic, open-access, website for collecting, displaying, and downloading ELECtron SCATtering cross sections and swarm parameters (mobility, diffusion coefficient, reaction rates, etc.) required for modeling low temperature, non-equilibrium plasmas. Contributors set up individual databases, and the available databases, indicated by the contributor’s chosen title, include mainly complete sets of electron-neutral scattering cross sections, although the option for introducing partial sets of cross sections exists. A database for measured swarm parameters is also part of LXCat, and this is a growing activity. On-line tools include options for browsing, plotting, and downloading cross section data. The electron energy distribution functions (edfs) in low temperature plasmas are in general non-Maxwellian, and LXCat provides an option for execution of an on-line Boltzmann equation solver to calculate the edf in homogeneous electric fields. Thus, the user can obtain electron transport and rate coefficients (averages over the edfs) in pure gases or gas mixtures over a range of values of the reduced electric fields strength, E/N, the ratio of the electric field strength to the neutral density, using cross sections from the available databases. New contributors are welcome and anyone wishing to create a database and upload data can request a username and password. LXCat is part of a larger, community

  2. Observations of plasma vortices in the vicinity of flow-braking: a case study

    Directory of Open Access Journals (Sweden)

    K. Keika

    2009-08-01

    Full Text Available We examine fast plasma flows and magnetic field fluctuations observed by THEMIS at 03:00–03:30 UT on 12 December 2007. All THEMIS probes are situated in the near-Earth plasma sheet (XSM>−10 RE with 1–2 RE spacecraft separations in azimuthal and radial directions. We focus on the observations of plasma convective flows made simultaneously by more than one THEMIS probe. At about 03:10 UT and 03:14 UT, the THEMIS P2 probe observed earthward flows of >100 km/s. The THEMIS P1 probe, located duskward and earthward of P2, observed tailward flows under a positive Bz. The inner most probe THEMIS P4, located at almost the same MLT as THEMIS P1 and P2, did not see any clear flow. We examine the convective flow patterns for the THEMIS observations. We conclude that plasma vortices are formed near the region where the earthward flows slow down and turn in azimuthal directions.

  3. Voyager microwave scintillation measurements of solar wind plasma parameters

    International Nuclear Information System (INIS)

    Martin, J.M.

    1985-01-01

    During the solar conjunctions of Voyager 1 and 2 spacecraft in August 1979, September 1980, and November 1982, temporal variations of intensity and frequency of the dual-wavelength (3.6 and 13 cm) radio transmissions from the spacecraft were observed and subsequently analyzed to infer characteristics of the solar wind plasma flow. Measurements of the temporal wave structure function were used to estimate the spectral index of the power law spatial spectrum of irregularities. Theoretical-intensity scintillation spectra were compared with measured intensity spectra to obtain least-squares estimates of (1) mean velocity, (2) random velocity, (3) axial ratio, and (4) electron density standard deviation. Uncertainties in parameter estimates were calculated by standard propagation of errors techniques. Mean velocity and electron density standard deviations in 1979-1980 show little dependence on solar latitude. Density standard deviation estimates were 3-10% of the background mean density and mean velocity estimates ranged from approx.200 km/s inside 17 solar radii to approx.300 km/s at 25 solar radii. 1982 density standard deviation estimates increased rapidly with latitude near 45 0 N, then sharply decreased north of that latitude, indicating the existence of a polar region of reduced fluctuations surrounded by a thin cone of strong density irregularities

  4. Chaos and bifurcations in periodic windows observed in plasmas

    International Nuclear Information System (INIS)

    Qin, J.; Wang, L.; Yuan, D.P.; Gao, P.; Zhang, B.Z.

    1989-01-01

    We report the experimental observations of deterministic chaos in a steady-state plasma which is not driven by any extra periodic forces. Two routes to chaos have been found, period-doubling and intermittent chaos. The fine structures in chaos such as periodic windows and bifurcations in windows have also been observed

  5. Stationary neoclassical profiles of plasma parameters in stellarators

    International Nuclear Information System (INIS)

    Danilkin, I.S.; Mineev, A.B.

    1991-01-01

    The properties of the neoclassical model of heat and particle transport are considered in connection with calculations of stationary profiles of the plasma parameters in stellarators. The most important feature is the poor agreement with real physical conditions of the boundary, which imposes the necessity of invoking either an additional anomalous transport or a special (although technically possible) consistency between the particle and heat sources in order to obtain a solution in the form of a correct monotonically decreasing profile. In search for monotonic stationary profiles maintained by external sources, it is ascertained that the neoclassical theory does not give rise to the well-known multivalued solutions for the ambipolar electric field

  6. The Diagnosis of Plasma Parameters in Surface Alloying Technique by Optical Emission Spectrometry

    International Nuclear Information System (INIS)

    Fu Yabo; Zhang Yuefei; Chen Qiang; Zhang Guangqiu; Gao Yuan; Wang Jianzhong; Kui Xiaoyun

    2006-01-01

    Electron density (Ne) in a glow discharge plasma for the surface alloying technique is diagnosed by optical emission spectrometry (OES). With CH 4 as the feeding gas, Ne is obtained by comparing the Hβ spectrum according to the Stark broadening effect. It is noticed that Ne varies with the working pressures (30 Pa to 70 Pa) and cathode voltages (500 V to 1000 V), respectively. Due to an abnormal glow discharge, Ne is between 1.71x10 15 /cm 3 to 6.64x10 15 /cm 3 and increases rapidly with working gas pressures and cathode voltages. The results show that OES is a useful method to measure the plasma parameters in a surface alloying glow discharge plasma

  7. Hollow core plasma channel generation

    International Nuclear Information System (INIS)

    Quast, Heinrich Martin

    2018-03-01

    The use of a hollow plasma channel in plasma-based acceleration has beneficial properties for the acceleration of electron and positron bunches. In the scope of the FLASHForward facility at DESY, the generation of such a plasma structure is examined. Therefore, the generation of a ring-shaped laser intensity profile with different techniques is analyzed. From the obtained intensity profiles the electron density of a hollow plasma channel is simulated in the focal region. Different parameters are scanned to understand their influence on the electron density distribution - an important parameter being, for example, the radius of the central region of the channel. In addition to the simulations, experiments are presented, during which a laser pulse is transformed into a hollow beam with a spiral phase plate. Subsequently, it forms a plasma during the interaction with hydrogen, where the plasma is imaged with interferometry. For energies above 0.9 mJ a hollow plasma structure can be observed at the location of first plasma formation.

  8. Observation of spatial resolution of ECR plasma on the MM-2 magnetic mirror

    International Nuclear Information System (INIS)

    Duan Shuyun; Gu Biao; Guan Weishu; Cheng Shiqing; Liu Rong; Chen Kangwei; Shang Zhenkui

    1991-04-01

    The measuring method and results of the ECR plasma properties taken from hard X-ray pinhole camera on the MM-2 magnetic mirror are presented. This non-destructive imaging method can directly display the spatial distribution of hot electron plasma. A frame of clear picture could be taken at one shot of discharge. The relationships between emission intensity and discharge parameters are also shown by experimental pictures

  9. Effect of basic physical parameters to control plasma meniscus and beam halo formation in negative ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, K. [Naruto University of Education, 748 Nakashima, Takashima, Naruto-cho, Naruto-shi, Tokushima 772-8502 (Japan); Okuda, S.; Nishioka, S.; Hatayama, A. [Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)

    2013-09-14

    Our previous study shows that the curvature of the plasma meniscus causes the beam halo in the negative ion sources: the negative ions extracted from the periphery of the meniscus are over-focused in the extractor due to the electrostatic lens effect, and consequently become the beam halo. In this article, the detail physics of the plasma meniscus and beam halo formation is investigated with two-dimensional particle-in-cell simulation. It is shown that the basic physical parameters such as the H{sup −} extraction voltage and the effective electron confinement time significantly affect the formation of the plasma meniscus and the resultant beam halo since the penetration of electric field for negative ion extraction depends on these physical parameters. Especially, the electron confinement time depends on the characteristic time of electron escape along the magnetic field as well as the characteristic time of electron diffusion across the magnetic field. The plasma meniscus penetrates deeply into the source plasma region when the effective electron confinement time is short. In this case, the curvature of the plasma meniscus becomes large, and consequently the fraction of the beam halo increases.

  10. Effect of basic physical parameters to control plasma meniscus and beam halo formation in negative ion sources

    International Nuclear Information System (INIS)

    Miyamoto, K.; Okuda, S.; Nishioka, S.; Hatayama, A.

    2013-01-01

    Our previous study shows that the curvature of the plasma meniscus causes the beam halo in the negative ion sources: the negative ions extracted from the periphery of the meniscus are over-focused in the extractor due to the electrostatic lens effect, and consequently become the beam halo. In this article, the detail physics of the plasma meniscus and beam halo formation is investigated with two-dimensional particle-in-cell simulation. It is shown that the basic physical parameters such as the H − extraction voltage and the effective electron confinement time significantly affect the formation of the plasma meniscus and the resultant beam halo since the penetration of electric field for negative ion extraction depends on these physical parameters. Especially, the electron confinement time depends on the characteristic time of electron escape along the magnetic field as well as the characteristic time of electron diffusion across the magnetic field. The plasma meniscus penetrates deeply into the source plasma region when the effective electron confinement time is short. In this case, the curvature of the plasma meniscus becomes large, and consequently the fraction of the beam halo increases

  11. Investigation of the effect of laser parameters on the target, plume and plasma behavior during and after laser-solid interaction

    Science.gov (United States)

    Stancalie, A.; Ciobanu, S. S.; Sporea, D.

    2017-09-01

    A detailed theoretical and experimental analysis is performed for a wide range of laser operating conditions, typical for laser induced breakdown spectroscopy (LIBS) and laser ablation (LA) experiments on copper metallic target. The plasma parameters were experimentally estimated from the line intensities ratio which reflects the relative population of neutral excited species in the plasma. In the case of LA experiments the highest temperature observed was 8210 ± 370 K. In case of LIBS measurements, a maximum temperature of 8123 K has been determined. The experimental results are in good agreement with a stationary, hydrodynamic model. We have theoretically investigated the plasma emission based on the generalized collisional-radiative model as implemented in the ADAS interconnected set of computer codes and data collections. The ionic population density distribution over the ground and excited states into the cooper plasma is graphically displayed as output from the code. The theoretical line intensity ratios are in good agreement with experimental values for the electron density and temperature range measured in our experiments.

  12. Some parameters of uranium hexafluoride plasma produced by products of nuclear reaction

    International Nuclear Information System (INIS)

    Batyrbekov, G.A.; Belyakova, Eh.A.

    1996-01-01

    The probe experimental results of investigation of uranium hexafluoride plasma produced in the centre of nuclear reactor core were demonstrated. Study of uranium hexafluoride plasma is continued by the following reasons: a possibility of U F 6 utilization as nuclear fuel, the utilization of U F 6 as volume source o ionization, search of active laser media compatible with U F 6 that is complicated by lack of constant rates data for most of plasma-chemical reactions with U F 6 and his dissociation products. Cylindrical probe volt-ampere characteristics (VAC) measured in U F 6 plasma at pressure 20 Torr and different thermal neutron fluxes and have following features: -firstly, it is possible to choose a linear part in the field of small positive potentials of probe (0-1) V; - secondary, ion branches of VAC have typical break which current of satiation corresponds to; -thirdly, probe VAC measured at small values of thermal neutron flux density are symmetrical. Diagnostics approaches were used for interpretation VAC of probe. The values of satiation current and linear part of electron branch were calculated, and such plasma parameters as conductivity, diffusion coefficient values of positive and negative ions were determined. The resonance recharge cross section was estimated on diffusion coefficient value

  13. A novel method for simultaneous observations of plasma ion and electron temperatures using a semiconductor-detector array

    International Nuclear Information System (INIS)

    Cho, T.; Numakura, T.; Kohagura, J.; Hirata, M.; Minami, R.; Watanabe, H.; Sasuga, T.; Nishizawa, Y.; Yoshida, M.; Nagashima, S.; Nakashima, Y.; Ogura, K.; Tamano, T.; Yatsu, K.; Miyoshi, S.

    2002-01-01

    A new method for a simultaneous observation of both plasma ion and electron temperatures is proposed using one semiconductor-detector array alone. This method will provide a new application of semiconductor-detector arrays for monitoring the key parameter set of nuclear-fusion triple product (i.e., ion temperatures, densities, and confinement time) as well as for clarifying physics mechanisms of energy transport between plasma ions and electrons under various plasma confining conditions. This method is developed on the basis of an alternative 'positive' use of a semiconductor 'dead layer'; that is, an SiO 2 layer is employed as a reliable ultra-thin energy analysis filter for low-energy charge-exchanged neutral particles from plasmas ranging in ion temperatures from 0.1 to several tens of kilo-electron-volts. Using recent fabrication techniques for the thin and uniform SiO 2 layers of the order of tens to hundreds of angstrom, our computer simulation and its experimental verification show the availability of such semiconductors for distinguishing neutral particles (for ion temperatures) from X-rays (for electron temperatures). These are simultaneously emitted from the plasmas into semiconductor detectors; however, we employ their quite different penetration lengths and the resultant different deposition depths and profiles in semiconductor materials. As a result, their output signals are distinguishable for these two different and fundamental species of plasmas

  14. Penentuan Efektifitas Oksitetrasiklin Melalui Parameter Farmakokinetik/farmakodinamik pada Plasma dan Jaringan Ayam Broiler

    Directory of Open Access Journals (Sweden)

    Agustina Dwi Wijayanti

    2010-06-01

    Full Text Available A study was conducted to determine the effectiveness of oxytetracycline on the basis of itspharmacokinetic/pharmacodynamic (PK/PD parameters in the plasma and tissues of broiler following a50 mg/kg single dose of intravenous administration. The male broiler were injected with oxytetracycline attarsal medial venous. The blood, liver, kidney and abdominal muscle were collected at 14 points of timesamplings. Blood was centrifuged to obtain plasma and all tissues were extracted with Mc Ilvine buffer.Drug concentration in samples was determined by High Performance Liquid Chromatography (HPLCusing AOAC standard reference for tetracycline. The pharmacokinetic parameters of oxytetracycline werecalculated using non compartment method. The results were as follows. For plasma: the AUC was 790,615,5 ?g/mL minute , Clearance was 63,242 mL/min/kg bb, Tmax/Cmax was 1 minute/0,7 ?g/mL, T1/2elimination was 6,4, hours, Vd was 37 L/kg. For liver ; AUC was 36418,89, minute , Tmax/Cmax was 16hours/17,15 ?g/g, and T1/2 elimination was 24,5, hours. For kidney; AUC6808,41 ?g/g minute , Tmax/Cmax 1 minute/16,73 ?g/g, , T1/2 elimination was 11,55 hours. For muscle; AUC was 3502 ?g/g minute,Tmax/Cmax was 1 minute/2,58 ?g/g, T1/2 elimination was 167,39 hours. The ratio of AUC/MIC inplasma and tissues appeared to a good pharmacokinetic/pharmacodynamic parameter to determine theeffectiveness of oxytetracycline.

  15. Time-space distribution of laser-induced plasma parameters and its influence on emission spectra of the laser plumes

    International Nuclear Information System (INIS)

    Ershov-Pavlov, E.A.; Katsalap, K.Yu.; Stepanov, K.L.; Stankevich, Yu.A.

    2008-01-01

    A physical model is developed accounting for dynamics and radiation of plasma plumes induced by nanosecond laser pulses on surface of solid samples. The model has been applied to simulate emission spectra of the laser erosion plasma at the elemental analysis of metals using single- and double-pulse excitation modes. Dynamics of the sample heating and expansion of the erosion products are accounted for by the thermal conductivity and gas dynamic equations, respectively, supposing axial symmetry. Using the resulting time-space distributions of the plasma parameters, emission spectra of the laser plumes are evaluated by solving the radiation transfer equation. Particle concentration in consecutive ionization stages is described by the Saha equation in the Debye approximation. The population of excited levels is determined according to Boltzmann distribution. Local characteristics determining spectral emission and absorption coefficients are obtained point-by-point along an observation line. Voigt spectral line profiles are considered with main broadening mechanisms taken into account. The plasma dynamics and plume emission spectra have been studied experimentally and by the model. A Q-switched Nd:YAG laser at 1064 nm wavelength has been used to irradiate Al sample with the pulses of 15 ns and 50 mJ duration and energy, respectively. It has resulted in maximum power density of 0.8 MW/cm 2 on the sample surface. The laser plume emission spectra have been recorded at a side-on observation. Problems of the spectra contrast and of the elemental analysis efficiency are considered relying on a comparative study of the measurement and simulation results at the both excitation modes

  16. Influence of the plasma pedestal parameters on ELM mitigation at low collisionality

    Energy Technology Data Exchange (ETDEWEB)

    Leuthold, Nils [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Universitaet Bayreuth, Universitaetsstrasse 30, 95440 Bayreuth (Germany); Suttrop, Wolfgang [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany)

    2016-07-01

    The control of Edge Localized Modes (ELMs) is of great importance for future fusion devices in order to provide longevity of the plasma facing components and a better overall plasma performance. In recent magnetic perturbation ELM mitigation experiments in ASDEX Upgrade at low pedestal collisionality, the dependence of ELM losses on pedestal parameters is investigated. It is found that the reduction of the stored energy loss associated with ELMs occurs in correlation with a reduction of edge density and edge pedestal pressure induced by the applied magnetic perturbation (''pedestal pump-out''). Significant ELM mitigation occurs at lowest densities, in a region of pedestal n-T parameter space that has not been accessible in ASDEX Upgrade without magnetic perturbations, and which is occupied by type-IV ELMs in DIII-D. The role of magnetic perturbations for ELM mitigation will be discussed in this context and attempts to counteract the confinement loss by increasing neutral beam injection power or pellet injection increases the ELM energy losses.

  17. Properties and parameters of the electron beam injected into the mirror magnetic trap of a plasma accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, V. V., E-mail: temple18@mail.ru; Novitsky, A. A.; Vinnichenko, L. A.; Umnov, A. M.; Ndong, D. O. [Peoples’ Friendship University of Russia (Russian Federation)

    2016-03-15

    The parameters of the injector of an axial plasma beam injected into a plasma accelerator operating on the basis of gyroresonance acceleration of electrons in the reverse magnetic field are determined. The trapping of the beam electrons into the regime of gyroresonance acceleration is numerically simulated by the particle- in-cell method. The optimal time of axial injection of the beam into a magnetic mirror trap is determined. The beam parameters satisfying the condition of efficient particle trapping into the gyromagnetic autoresonance regime are found.

  18. Numerical study for determining PF coil system parameters in MHD equilibrium of KT-2 tokamak plasma

    International Nuclear Information System (INIS)

    Ryu, J.; Hong, S.H.; Lee, K.W.; Hong, B.G.; In, S.R.; Kim, S.K.

    1995-01-01

    The KT-2 is a large-aspect-ratio medium-sized divertor tokamak in the conceptual design phase and planned to be operational in 1998 at the Korea Atomic Energy Research Institute (KAERI). Plasma equilibrium in tokamak can be acquired by controlling the current of poloidal field (PF) coils in appropriate geometries and positions. In this study, the authors have performed numerical calculations to achieve the various equilibrium conditions fitting given plasma shapes and satisfying PF current limitations. Usually an ideal magnetohydrodynamic (MHD) equation is used to obtain the equilibrium solution of tokamak plasma, and it is practical to take advantage of a numerical method in solving the MHD equation because it has nonlinear source terms. Two equilibrium codes have been applied to find a double-null configuration of free-boundary tokamak plasma in KT-2: one is of the authors' own developing and the other is a free-boundary tokamak equilibrium code (FBT) that has been used mainly for the verification of developed code's results. PF coil system parameters including their positions and currents are determined for the optimization of input power required when the specifications of KT-2 tokamak are met. Then, several sets of equilibrium conditions during the tokamak operation are found to observe the changes of poloidal field currents with the passing of operation time step, and the basic stability problems related with the magnetic field structure is also considered

  19. L-carnitine plasma levels in dogs and cats. A diagnostic parameter?

    International Nuclear Information System (INIS)

    Fischer, J.

    1993-04-01

    The relation between levels of carnitine in plasma and lesions of organs should be demonstrated. 52 dogs and 58 cats examined in veterinary clinics for several reasons and routinely screened for blood chemistry also were analysed for free plasma carnitine by a radiocarbon method. Increased carnitine levels were observed in both species in case of heart, liver and kidney disorders. Additionally the influence of food intake on carnitine levels in dogs was studied. Postprandial changes were insignificant. Because of lack of information about carnitine levels in cats and changes with age plasma carnitine was determined in cats and kittens. The range of normal values was 8.2 to 24.2 μmol/l without any significance of age

  20. Plasma Turbulence in Earth's Magnetotail Observed by the Magnetospheric Multiscale Mission

    Science.gov (United States)

    Mackler, D. A.; Avanov, L. A.; Boardsen, S. A.; Pollock, C. J.

    2017-12-01

    Magnetic reconnection, a process in which the magnetic topology undergoes multi-scale changes, is a significant mechanism for particle energization as well as energy dissipation. Reconnection is observed to occur in thin current sheets generated between two regions of magnetized plasma merging with a non-zero shear angle. Within a thinning current sheet, the dominant scale size approaches first the ion and then electron kinetic scale. The plasma becomes demagnetized, field lines transform, then once again the plasma becomes frozen-in. The reconnection process accelerates particles, leading to heated jets of plasma. Turbulence is another fundamental process in collision less plasmas. Despite decades of turbulence studies, an essential science question remains as to how turbulent energy dissipates at small scales by heating and accelerating particles. Turbulence in both plasmas and fluids has a fundamental property in that it follows an energy cascade into smaller scales. Energy introduced into a fluid or plasma can cause large scale motion, introducing vorticity, which merge and interact to make increasingly smaller eddies. It has been hypothesized that turbulent energy in magnetized plasmas may be dissipated by magnetic reconnection, just as viscosity dissipates energy in neutral fluid turbulence. The focus of this study is to use the new high temporal resolution suite of instruments on board the Magnetospheric MultiScale (MMS) mission to explore this hypothesis. An observable feature of the energy cascade in a turbulent magnetized plasma is its similarity to classical hydrodynamics in that the Power Spectral Density (PSD) of turbulent fluctuations follows a Kolmogorov-like power law (Image-5/3). We use highly accurate (0.1 nT) Flux Gate Magnetometer (FGM) data to derive the PSD as a function of frequency in the magnetic fluctuations. Given that we are able to confirm the turbulent nature of the flow field; we apply the method of Partial Variance of Increments (PVI

  1. First observations of acceleration of injected electrons in a laser plasma beatwave experiment

    International Nuclear Information System (INIS)

    Ebrahim, N.A.; Martin, F.; Bordeur, P.; Heighway, E.A.; Matte, J.P.; Pepin, H.; Lavigne, P.

    1986-01-01

    The first experimental observations of acceleration of injected electrons in a laser driven plasma beatwave are presented. The plasma waves were excited in an ionized gas jet, using a short pulse high intensity CO 2 laser with two collinearly propagating beams (at λ = 9.6 μm and 10.6 μm) to excite a fast wave (v/sub p/ = c). The source of electrons was a laser plasma produced on an aluminum slab target by a third, synchronized CO 2 laser beam. A double-focusing dipole magnet was used to energy select and inject electrons into the beatwave, and a second magnetic spectrograph was used to analyze the accelerated electrons. Electron acceleration was only observed when the appropriate resonant plasma density was produced (∼ 10 17 cm -3 ), the two laser lines were incident on the plasma, and electrons were injected into this plasma from an external source

  2. Observation of dielectronic satellites in the K-spectrum of argon ions in plasma produced by femtosecond laser pulses

    International Nuclear Information System (INIS)

    Magunov, A.I.; Faenov, A.Ya.; Skobelev, I.Yu.; Pikuz, T.A.; Biemont, E.; Quinet, P.; Blasco, F.; Bonte, C.; Dorchies, F.; Caillaud, T.; Salin, F.; Stenz, C.

    2002-01-01

    The satellite structure of 1s2p 1,3 P 1 -1s 21 S 0 lines of the He-like argon ion in plasma produced by a 45-fs laser pulse in a gas-jet cluster target is measured with a high spectral resolution. Radiation transitions 2p → 1s from autoionizing states (AISs) are detected for ions ranging from Li-like to F-like. The spectrum observed is theoretically simulated with the use of the spectroscopic data for the AISs of multicharged ions obtained within the multiconfiguration relativistic Hartree-Fock method. Good agreement with experimental data is obtained when the main population channels of these states are taken into account for typical values of cluster-target plasma parameters

  3. [Measurement of plasma parameters in cluster hexagon pattern discharge by optical emission spectrum].

    Science.gov (United States)

    Dong, Li-Fang; Shen, Zhong-Kai; Li, Xin-Chun; Liu, Liang; Lu, Ning; Shang, Jie

    2012-09-01

    The cluster hexagon pattern was obtained in a dielectric barrier discharge in air/argon for the first time. Three plasma parameters, i. e. the molecular vibrational temperature, the molecular rotational temperature and the average electron energy of individual cluster in cluster hexagon pattern discharge, were studied by changing the air content. The molecular vibrational temperature and the molecular rotational temperature were calculated using the second positive band system of nitrogen molecules (C 3IIu --> B 3IIg) and the first negative band system of nitrogen molecular ions (B 2Sigma(u)+ --> Chi2 Sigma(g)+). The relative intensities of the first negative system of nitrogen molecular ions (391. 4 nm) and nitrogen molecules emission spectrum line (337.1 nm) were analyzed for studying the variations of the electron energy. It was found that the three plasma parameters of individual cluster in cluster hexagon pattern increase with air content increasing from 16% to 24%.

  4. Neural network-based preprocessing to estimate the parameters of the X-ray emission of a single-temperature thermal plasma

    Science.gov (United States)

    Ichinohe, Y.; Yamada, S.; Miyazaki, N.; Saito, S.

    2018-04-01

    We present data preprocessing based on an artificial neural network to estimate the parameters of the X-ray emission spectra of a single-temperature thermal plasma. The method finds appropriate parameters close to the global optimum. The neural network is designed to learn the parameters of the thermal plasma (temperature, abundance, normalization and redshift) of the input spectra. After training using 9000 simulated X-ray spectra, the network has grown to predict all the unknown parameters with uncertainties of about a few per cent. The performance dependence on the network structure has been studied. We applied the neural network to an actual high-resolution spectrum obtained with Hitomi. The predicted plasma parameters agree with the known best-fitting parameters of the Perseus cluster within uncertainties of ≲10 per cent. The result shows that neural networks trained by simulated data might possibly be used to extract a feature built in the data. This would reduce human-intensive preprocessing costs before detailed spectral analysis, and would help us make the best use of the large quantities of spectral data that will be available in the coming decades.

  5. Nonlinear processes in laser-produced dense plasma (observation of the fractional harmonics)

    International Nuclear Information System (INIS)

    Lyu, K.S.

    1988-01-01

    One of the main issues of laser plasma physics interactions is harmonic generation. The harmonic emission spectrum provides clues as to which non-linear processes take place in the plasma. Several effects contribute to a given line as judged from the complexity of the actual spectra. Unfolding of them has not been done satisfactorily yet. Harmonic lines with half integer or integer orders have been observed, but the physics are far from complete. In this dissertation research, we observed the usual second harmonic generation and a set of fractional harmonics which we believe have been observed for the first time in plasma physics. The plasma was produced by a high power laser and we have characterized its properties from the analysis of the radiation spectra, including the harmonic lines, as measured using the methods of transient spectroscopy. We produced the plasma with a Nd:glass laser which had a 65 nsec pulse width (FWHM) with a total energy of up to 6 Joules. The targets were steel alloys, copper, and aluminum. The harmonic generation from the plasma with a planar metal target was not strong. But, it became stronger when we made a dead hole (cavity) at the laser spot on the target surface. The second harmonic line appears first before the time of the peak of laser pulse. The fractional harmonics, which are related to the laser wavelength by rational number other than integers or half integers, appear near or after the time of the laser peak and weaker in UV wavelength range but stronger if some atomic emission line are near by. To understand the plasma evolution better, we developed computer simulation codes. The codes contain all relevant processes necessary to compute the plasma evolution

  6. Plasma Electronics. Theoretical and Experimental Investigations of Plasma Nonlinearity in the Powerful Microwave Oscillators

    International Nuclear Information System (INIS)

    Bliokh, Yu.P.

    2001-01-01

    either new steady-state, or automodulation regime can appear. Developed theory predicts appearance of a deep low-frequency automodulation of microwave power when the beam current exceeds some threshold. This effect was observed experimentally and parameters of automodulation are close to calculated ones. The ion-sound waves, which are the reason of auto modulation appearance, were also observed experimentally. It was shown theoretically and experimentally that non-stationary self-consistent plasma density and microwave power redistribution along the system can be the reason of microwave pulse shortening and power limiting mechanism in plasma-filled microwave radiation sources. It was shown also that the same mechanism leads to the stochastization of the microwave signal. Stochastic radiation, which is obtained by plasma-filled structure use, differs strongly by it spectral density homogeneity from stochastic radiation of analogous vacuum devices

  7. Effect of different parameters governing the stability of drift wave in a magnetised plasma

    International Nuclear Information System (INIS)

    Elashkar, F.F.

    1990-01-01

    Influence of the governing parameters, such as electron drift parallel speed, parallel wave length, electron-neutral and ion-neutral collision frequencies, electron temperature and magnetic field, on the stability of drift wave in a magnetized plasma has been studied experimentally and theoretically using a full numerical solution of the exact equation. Drift wave has been excited by a positively biased grid; at a threshold grid potential secondary excitation and ionisation processes take place in the ejected beam of plasma. Effect of the applied magnetic field on the probability of these processes is discussed. Grid positive potential, electron-neutral collision, parallel wave length, electron temperature and speed are found to be destabilizing, While ion neutral collision is stabilizing. Using a new parameter β, the effect of magnetic field is investigated and it is destabilizing only upto a certain limit. (author). 11 figs., 21 refs

  8. Monitoring of plasma butyrylcholinesterase activity and hematological parameters in pesticide sprayers.

    Science.gov (United States)

    Rastogi, S K; Singh, Vipul K; Kesavachandran, C; Jyoti; Siddiqui, M K J; Mathur, N; Bharti, R S

    2008-04-01

    To evaluate the health impact of spraying organophosphorus insecticides (OPs), 34 male sprayers in the mango belt of Malihabad, a small town located 27 km from Lucknow in North India was selected. Plasma butyryl cholinesterase (PBChE) and complete blood count were assessed among sprayers after spraying pesticides and the findings obtained were compared with those determined in a reference group (n = 18). The most common symptoms observed were burning sensation in the eyes (8.82%), itching/skin irritation (23.52%) and chest symptoms (32.35%) in the exposed workers. Plasma butyrylcholinesterase (PBChE) was significantly decreased in workers. The results indicated significant decrease in the mean value of hemoglobin, hematocrit and platelets count; however, significantly higher count of leukocytes was also observed in the exposed group (sprayers) compared to that observed in the control group (P < 0.05). Monitoring of PBChE in pesticide sprayers could be useful to predict and prevent health hazards of OPs.

  9. Experimental and numerical investigation of plasma parameters in the magnetosheath

    Directory of Open Access Journals (Sweden)

    Dobreva Polya

    2018-01-01

    Full Text Available We investigate the behaviour of the plasma parameters in the magnetosheath in a case when Interball-1 satellite stayed in the magnetosheath, crossing the tail magnetopause. In our analysis we apply the numerical magnetosheath-magnetosphere model as a theoretical tool. The bow shock and the magnetopause are self-consistently determined in the process of the solution. The flow in the magnetosheath is governed by the Euler equations of compressible ideal gas. The magnetic field in the magnetosphere is calculated by a variant of the Tsyganenko model, modified to account for an asymmetric magnetopause. Also, the magnetopause currents in Tsyganenko model are replaced by numericaly calulated ones. Measurements from WIND spacecraft are used as a solar wind monitor. The results demonstrate a good agreement between the model-calculated and measured values of the parameters under investigation.

  10. First Observation of the Seeded Proton Bunch Self-Modulation in Plasma

    CERN Document Server

    AUTHOR|(CDS)2093171; Vincke, Helmut

    In this thesis I observe experimentally and study in simulations the seeded selfmodulation of a relativistic proton bunch in AWAKE, the Advanced Proton Driven Plasma Wakefield Acceleration Experiment. The 400 GeV/c proton bunch from the CERN SPS with a rms length of 12 cm propagates in a 10m long plasma with a density adjustable between 2-10x10^14 electrons/cm3. The seeded self-modulation process results in focusing and defocusing of the protons, thereby forming a bunch train that resonantly drives wakefields to large amplitudes. I use the two-screen measurement setup, to observe the result of the proton bunch self-modulation and to learn about its physics (i.e. growth of the process). The idea is to obtain images of protons that were defocused by the transverse wakefields, 2 and 10m downstream the end of the plasma. From these images I determine the maximum transverse momentum of the defocused protons as well as infer their point of origin along the plasma. I use simulations to guide the understanding of the...

  11. Study of thermal and electrical parameters of workpieces during spray coating by electrolytic plasma jet

    International Nuclear Information System (INIS)

    Khafizov, A A; Shakirov, Yu I; Valiev, R A; Valiev, R I; Khafizova, G M

    2016-01-01

    In this paper the results are presented of thermal and electrical parameters of products in the system bottom layer - intermediate layer when applying protective coatings of ferromagnetic powder by plasma spray produced in an electric discharge with a liquid cathode, on steel samples. Temperature distribution and gradients in coating and intermediate coating were examined. Detailed descriptions of spray coating with ferromagnetic powder by plasma jet obtained in electrical discharge with liquid cathode and the apparatus for obtaining thereof is provided. Problem has been solved by using of Fourier analysis. Initial data for calculations is provided. Results of numerical analysis are provided as temporal functions of temperature in contiguity between coating and intermediate coating as well as temporal function of the value Q=q-φ; where q is density of heat current directed to the free surface of intermediate coating, φ is density of heat current in contiguity between coating and intermediate coating. The analysis of data given shows that in the systems of contact heat exchange bottom layer-intermediate layer with close values of the thermophysical characteristics of constituting materials is observed a slow increase of the temperature of the contact as a function of time. (paper)

  12. Reconstruction of the ion plasma parameters from the current measurements: mathematical tool

    Directory of Open Access Journals (Sweden)

    E. Séran

    Full Text Available Instrument d’Analyse du Plasma (IAP is one of the instruments of the newly prepared ionospheric mission Demeter. This analyser was developed to measure flows of thermal ions at the altitude of ~ 750 km and consists of two parts: (i retarding potential analyser (APR, which is utilised to measure the energy distribution of the ion plasma along the sensor look direction, and (ii velocity direction analyser (ADV, which is used to measure the arrival angle of the ion flow with respect to the analyser axis. The necessity to obtain quick and precise estimates of the ion plasma parameters has prompted us to revise the existing mathematical tool and to investigate different instrumental limitations, such as (i finite angular aperture, (ii grid transparency, (iii potential depression in the space between the grid wires, (iv losses of ions during their passage between the entrance diaphragm and the collector. Simple analytical expressions are found to fit the currents, which are measured by the APR and ADV collectors, and show a very good agreement with the numerical solutions. It was proven that the fitting of the current with the model functions gives a possibility to properly resolve even minor ion concentrations and to find the arrival angles of the ion flow in the multi-species plasma. The discussion is illustrated by an analysis of the instrument response in the ionospheric conditions which are predicted by the International Reference Ionosphere (IRI model.

    Key words. Ionosphere (plasma convection; instruments and techniques – Space plasma physics (experimental and mathematical techniques

  13. Reconstruction of the ion plasma parameters from the current measurements: mathematical tool

    Directory of Open Access Journals (Sweden)

    E. Séran

    2003-05-01

    Full Text Available Instrument d’Analyse du Plasma (IAP is one of the instruments of the newly prepared ionospheric mission Demeter. This analyser was developed to measure flows of thermal ions at the altitude of ~ 750 km and consists of two parts: (i retarding potential analyser (APR, which is utilised to measure the energy distribution of the ion plasma along the sensor look direction, and (ii velocity direction analyser (ADV, which is used to measure the arrival angle of the ion flow with respect to the analyser axis. The necessity to obtain quick and precise estimates of the ion plasma parameters has prompted us to revise the existing mathematical tool and to investigate different instrumental limitations, such as (i finite angular aperture, (ii grid transparency, (iii potential depression in the space between the grid wires, (iv losses of ions during their passage between the entrance diaphragm and the collector. Simple analytical expressions are found to fit the currents, which are measured by the APR and ADV collectors, and show a very good agreement with the numerical solutions. It was proven that the fitting of the current with the model functions gives a possibility to properly resolve even minor ion concentrations and to find the arrival angles of the ion flow in the multi-species plasma. The discussion is illustrated by an analysis of the instrument response in the ionospheric conditions which are predicted by the International Reference Ionosphere (IRI model.Key words. Ionosphere (plasma convection; instruments and techniques – Space plasma physics (experimental and mathematical techniques

  14. Observer-based linear parameter varying H∞ tracking control for hypersonic vehicles

    Directory of Open Access Journals (Sweden)

    Yiqing Huang

    2016-11-01

    Full Text Available This article aims to develop observer-based linear parameter varying output feedback H∞ tracking controller for hypersonic vehicles. Due to the complexity of an original nonlinear model of the hypersonic vehicle dynamics, a slow–fast loop linear parameter varying polytopic model is introduced for system stability analysis and controller design. Then, a state observer is developed by linear parameter varying technique in order to estimate the unmeasured attitude angular for slow loop system. Also, based on the designed linear parameter varying state observer, a kind of attitude tracking controller is presented to reduce tracking errors for all bounded reference attitude angular inputs. The closed-loop linear parameter varying system is proved to be quadratically stable by Lypapunov function technique. Finally, simulation results show that the developed linear parameter varying H∞ controller has good tracking capability for reference commands.

  15. Plasma-parameter measurements using neutral-particle-beam attenuation

    International Nuclear Information System (INIS)

    Foote, J.H.; Molvik, A.W.; Turner, W.C.

    1982-01-01

    Intense and energetic neutral-particle-beam injection used for fueling or heating magnetically confined, controlled-fusion experimental plasmas can also provide diagnostic measurements of the plasmas. The attenuation of an atomic beam (mainly from charge-exchange and ionization interactions) when passing through a plasma gives the plasma line density. Orthogonal arrays of highly collimated detectors of the secondary-electron-emission type have been used in magnetic-mirror experiments to measure neutral-beam attenuation along chords through the plasma volume at different radial and axial positions. The radial array is used to infer the radial plasma-density profile; the axial array, to infer the axial plasma-density profile and the ion angular distribution at the plasma midplane

  16. On scattering diagnostics with periodically pulsed lasers to follow the continuous evolution of time dependent plasma parameters

    International Nuclear Information System (INIS)

    Hellermann, M. von; Hirsch, K.; Doeble, H.F.

    1977-04-01

    The possibilities to use periodically pulsed lasers for plasma scattering diagnostics are discussed. An experiment with succesful application of a periodically pulsed frequency-doubled Nd:YAG laser is described and results are given. Application of the method to monitor continuously, with millisecond time resolution, parameters of Tokamak type plasmas, is considered. (orig.) [de

  17. Design and construction the identification of nitriding plasma process parameters using personal computer based on serial communication

    International Nuclear Information System (INIS)

    Frida Iswinning Diah; Slamet Santosa

    2012-01-01

    Design and construction the identification of process parameters using personal computer based on serial communication PLC M-series has been done. The function of this device is to identify the process parameters of a system (plan), to which then be analyzed and conducted a follow-up given to the plan by the user. The main component of this device is the M-Series T100MD1616 PLC and personal computer (PC). In this device the data plan parameters obtained from the corresponding sensor outputs in the form of voltage or current. While the analog parameter data is adjusted to the ADC analog input of the PLC using a signal conditioning system. Then, as the parameter is processed by the PLC then sent to a PC via RS232 to be displayed in the form of graphs or tables and stored in the database. Software to program the database is created using Visual Basic Programming V-6. The device operation test is performed for the measurement of temperature parameter and vacuum level on the plasma nitriding machine. The results indicate that the device has functioning as an identification device parameters process of plasma nitriding machine. (author)

  18. The lobe to plasma sheet boundary layer transition: Theory and observations

    International Nuclear Information System (INIS)

    Schriver, D.; Ashour-Abdalla, M.; Treumann, R.; Nakamura, M.; Kistler, L.M.

    1990-01-01

    The lobe and the plasma sheet boundary layer in the Earth's magnetotail are regions of different plasma conditions and share a common interface. The transition from the lobe to the plasma sheet boundary layer is examined here using AMPTE/IRM data. When the satellite crossed from the lobe to the plasma sheet boundary layer, intense narrow banded wave bursts at 1 kHz were observed an d then broadband electrostatic noise (BEN) immediately followed. Simultaneous with the onset of BEN, high energy earthward streaming proton beams at > 40 keV (> 2,700 km/s) were detected. These results are used as input into a numerical simulation to study ion beam instabilities in the PSBL

  19. Identification of Plasma Parameters and Optimization of Magnetic Sensors in the Superconducting Steady-State Tokamak-1 Using Neural Networks

    International Nuclear Information System (INIS)

    Sengupta, A.; Ranjan, P.

    2001-01-01

    In this paper, we examine the possibility of using a multilayered feedforward neural network to extract tokamak plasma parameters from magnetic measurements as an improvement over the traditional methodology of function parametrization. It is also used to optimize the number and locations of the magnetic diagnostics designed for the tokamak. This work has been undertaken with the specific purpose of application of the neural network technique to the newly designed (and currently under fabrication) Superconducting Steady-State Tokamak-1 (SST-1). The magnetic measurements will be utilized to achieve real-time control of plasma shape, position, and some global profiles. A trained neural network is tested, and the results of parameter identification are compared with function parametrization. Both techniques appear well suited for the purpose, but a definite improvement with neural networks is observed. Although simulated measurements are used in this work, confidence regarding the network performance with actual experimental data is ensured by testing the network's noise tolerance with Gaussian noise of up to 10%. Finally, three possible methods of ranking the diagnostics in decreasing order of importance are suggested, and the neural network is used to optimize the number and locations of the magnetic sensors designed for SST-1. The results from the three methods are compared with one another and also with function parametrization. Magnetic probes within the plasma-facing side of the outboard limiter have been ranked high. Function parametrization and one of the neural network methods show a distinct tendency to favor the probes in the remote regions of the vacuum vessel, proving the importance of redundancy. Fault tolerance of the optimized network is tested. The results obtained should, in the long run, help in the decision regarding the final effective set of magnetic diagnostics to be used in SST-1 for reconstruction of the control parameters

  20. Theory and observation of compressional Alfven eigenmodes in low aspect ratio plasma

    International Nuclear Information System (INIS)

    Gorelenkov, N.N.

    2002-01-01

    A new theory of radially and poloidally localized Compressional Alfven Eigenmodes (CAE) in low aspect ratio plasma is reported. The theory is applied to identify recently observed instabilities in the MHz frequency range in National Spherical Torus experiments (NSTX). The frequency of observed CAEs is correlated with the characteristic Alfven velocity of the plasma. The observed high frequency modes are explained as CAEs driven by energetic beam ions. The CAE frequency is determined by the Alfven frequency at the mode location on the low field side of the plasma and is given approximately by ω CAE v A m=r, where m is the poloidal mode number, and r is the local minor radius. CAEs are destabilized by free energy in the energetic ion velocity space gradient via Doppler shifted cyclotron resonance with beam ions. Properties of the CAE instability driven by different NBI ion distributions are presented. (author)

  1. The producing of an ECR plasma using 2450MHz Whistler Wave and the investigating of its parameters

    International Nuclear Information System (INIS)

    Fang Yude; Zhang Jiande; Fu Keming; Lu Xiangyu; Liu Dengcheng; Wang Xianyu; Xie Weidong; Bao Dinghua; Yin Xiejin

    1988-12-01

    A stable ECR plasma was produced and sustained in HER mirror using 2450MHz Whistler wave. The parameters of the ECR plasma and their chaining characters were studied in detail and were compared with those of the DC discharge plasmas. The conclusion is that the ECR plasma is a high ionizability, low temperature, middle density plasma, its peak density may much exceed the cutoff density of the pump wave (when ω = ω pe ) and arrive at the order of 10 12 cm -3 . The ECR plasma includes some high energy hot electrons (20Kev-200Kev) and middle energy warm electrons (< 20Kev). Those two kinds of electron created some strong X-ray emissions in a wide frequency range. The ECR plasma has higher edge density and can strongly interact with the wall. (author). 9 refs, 17 figs

  2. A NANOFLARE-BASED CELLULAR AUTOMATON MODEL AND THE OBSERVED PROPERTIES OF THE CORONAL PLASMA

    Energy Technology Data Exchange (ETDEWEB)

    Fuentes, Marcelo López [Instituto de Astronomía y Física del Espacio, CONICET-UBA, CC. 67, Suc. 28, 1428 Buenos Aires (Argentina); Klimchuk, James A., E-mail: lopezf@iafe.uba.ar [NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States)

    2016-09-10

    We use the cellular automaton model described in López Fuentes and Klimchuk to study the evolution of coronal loop plasmas. The model, based on the idea of a critical misalignment angle in tangled magnetic fields, produces nanoflares of varying frequency with respect to the plasma cooling time. We compare the results of the model with active region (AR) observations obtained with the Hinode /XRT and SDO /AIA instruments. The comparison is based on the statistical properties of synthetic and observed loop light curves. Our results show that the model reproduces the main observational characteristics of the evolution of the plasma in AR coronal loops. The typical intensity fluctuations have amplitudes of 10%–15% both for the model and the observations. The sign of the skewness of the intensity distributions indicates the presence of cooling plasma in the loops. We also study the emission measure (EM) distribution predicted by the model and obtain slopes in log(EM) versus log(T) between 2.7 and 4.3, in agreement with published observational values.

  3. A Nanoflare-Based Cellular Automaton Model and the Observed Properties of the Coronal Plasma

    Science.gov (United States)

    Lopez-Fuentes, Marcelo; Klimchuk, James Andrew

    2016-01-01

    We use the cellular automaton model described in Lopez Fuentes and Klimchuk to study the evolution of coronal loop plasmas. The model, based on the idea of a critical misalignment angle in tangled magnetic fields, produces nanoflares of varying frequency with respect to the plasma cooling time. We compare the results of the model with active region (AR) observations obtained with the Hinode/XRT and SDOAIA instruments. The comparison is based on the statistical properties of synthetic and observed loop light curves. Our results show that the model reproduces the main observational characteristics of the evolution of the plasma in AR coronal loops. The typical intensity fluctuations have amplitudes of 10 percent - 15 percent both for the model and the observations. The sign of the skewness of the intensity distributions indicates the presence of cooling plasma in the loops. We also study the emission measure (EM) distribution predicted by the model and obtain slopes in log(EM) versus log(T) between 2.7 and 4.3, in agreement with published observational values.

  4. PLASMA DIAGNOSTICS OF AN EIT WAVE OBSERVED BY HINODE/EIS AND SDO/AIA

    Energy Technology Data Exchange (ETDEWEB)

    Veronig, A. M.; Kienreich, I. W.; Muhr, N.; Temmer, M. [Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Goemoery, P. [Astronomical Institute, Slovak Academy of Sciences, SK-05960 Tatranska Lomnica (Slovakia); Vrsnak, B. [Hvar Observatory, Faculty of Geodesy, Kaciceva 26, 1000 Zagreb (Croatia); Warren, H. P., E-mail: astrid.veronig@uni-graz.at [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2011-12-10

    We present plasma diagnostics of an Extreme-Ultraviolet Imaging Telescope (EIT) wave observed with high cadence in Hinode/Extreme-Ultraviolet Imaging Spectrometer (EIS) sit-and-stare spectroscopy and Solar Dynamics Observatory/Atmospheric Imaging Assembly imagery obtained during the HOP-180 observing campaign on 2011 February 16. At the propagating EIT wave front, we observe downward plasma flows in the EIS Fe XII, Fe XIII, and Fe XVI spectral lines (log T Almost-Equal-To 6.1-6.4) with line-of-sight (LOS) velocities up to 20 km s{sup -1}. These redshifts are followed by blueshifts with upward velocities up to -5 km s{sup -1} indicating relaxation of the plasma behind the wave front. During the wave evolution, the downward velocity pulse steepens from a few km s{sup -1} up to 20 km s{sup -1} and subsequently decays, correlated with the relative changes of the line intensities. The expected increase of the plasma densities at the EIT wave front estimated from the observed intensity increase lies within the noise level of our density diagnostics from EIS Fe XIII 202/203 A line ratios. No significant LOS plasma motions are observed in the He II line, suggesting that the wave pulse was not strong enough to perturb the underlying chromosphere. This is consistent with the finding that no H{alpha} Moreton wave was associated with the event. The EIT wave propagating along the EIS slit reveals a strong deceleration of a Almost-Equal-To -540 m s{sup -2} and a start velocity of v{sub 0} Almost-Equal-To 590 km s{sup -1}. These findings are consistent with the passage of a coronal fast-mode MHD wave, pushing the plasma downward and compressing it at the coronal base.

  5. The effect of axial ion parameters on the properties of glow discharge polymer in T2B/H2 plasma

    Science.gov (United States)

    Ai, Xing; He, Xiao-Shan; Huang, Jing-Lin; He, Zhi-Bing; Du, Kai; Chen, Guo

    2018-03-01

    Glow discharge polymer (GDP) films were fabricated using plasma-enhanced chemical vapor deposition. The main purpose of this work was to explore the correlations of plasma parameters with the surface morphology and chemical structure of GDP films. The intensities of main positive ions and ion energy as functions of axial distances in T2B/H2 plasma were diagnosed using energy-resolved mass spectrometry. The surface morphology and chemical structure were characterized as functions of axial distances using a scanning electron microscope and Fourier transform infrared spectroscopy, respectively. As the axial distance increases, both the intensities of positive ions and high energy ions decreases, and dissociation weakens while polymerization enhances. This leads to the weakening of the cross-linking structure of GDP films and the formation of dome defects on films. Additionally, high energy ions could introduce a strong etching effect to form etching pits. Therefore, an axial distance of about 20 mm was found to be the optimal plasma parameter to prepare the defect-free GDP films. These results could help one to find the optimal plasma parameters for GDP film deposition.

  6. Observation of Dust Particle Gyromotion in a Magnetized Dusty Plasma

    Science.gov (United States)

    Compton, C. S.; Amatucci, W. E.; Gatling, G.; Tejero, E.

    2008-11-01

    In dusty plasma research, gyromotion of the dust has been difficult to observe experimentally. Previous experiments by Amatucci et al. have shown gyromotion of a single dust particle [1]. This early work was performed with alumina dust that had a size distribution and non-uniformly shaped particles. In the current experiment, evidence of spherical, monodispersed, dust particles exhibiting gyromotion has been observed. Silica particles 0.97 micrometers in diameter are suspended in a DC glow discharge argon plasma. The experiment is performed in the Naval Research Laboratory's DUsty PLasma EXperiment (DUPLEX Jr.). DUPLEX is a 61-cm tall by 46-cm diameter acrylic chamber allowing full 360 degree optical access for diagnostics. The neutral pressure for the experiment is 230 mTorr with a 275 V bias between the circular electrodes. The electrodes have a separation of 4 cm. A strong magnetic field is created by 2 pairs of neodymium iron boride magnets placed above and below the anode and cathode respectively. The resulting field is 1.4 kG. The dust particles are illuminated with a 25 mW, 672 nm laser. Images are captured using an intensified CCD camera and a consumer digital video cassette recorder. Recent evidence of gyromotion of spherical, monodispersed, dust particles will be presented. [1] Amatucci, W.E., et al., Phys. Plasmas, 11, 2097 (2004)

  7. First observation of the depolarization of Thomson scattering radiation by a fusion plasma

    Science.gov (United States)

    Giudicotti, L.; Kempenaars, M.; McCormack, O.; Flanagan, J.; Pasqualotto, R.; contributors, JET

    2018-04-01

    We report the first experimental observation of the depolarization of the Thomson scattering (TS) radiation, a relativistic effect expected to occur in very high {{T}e} plasmas and never observed so far in a fusion machine. A set of unused optical fibers in the collection optics of the high resolution Thomson scattering system of JET has been used to detect the depolarized TS radiation during a JET campaign with {{T}e}≤slant 8 keV . A linear polarizer with the axis perpendicular to the direction of the incident E-field was placed in front of a fiber optic pair observing a region close to the plasma core, while another fiber pair with no polariser simultaneously observed an adjacent plasma region. The measured intensity ratio was found to be consistent with the theory, taking into account sensitivity coefficients of the two measurement channels determined with post-experiment calibrations and Raman scattering. This depolarization effect is at the basis of polarimetric TS, a different and complementary method for the analysis of TS spectra that can provide significant advantages for {{T}e} measurements in very hot plasmas such as in ITER ≤ft({{T}e}≤slant 40 keV \\right) .

  8. Coaxial discharge plasma parameters and radiation emission

    International Nuclear Information System (INIS)

    Solimen, H.M.

    1993-01-01

    Results are reported for experiments carried out on a Mather type coaxial discharge plasma device. Experimental measurements of the electron temperature and density for the plasma propagated from the coaxial discharge are determined by using a biased double electric probe. The experimental results illustrated that , there are two groups of the plasma in the ejected plasma bulk, at 9 cm from the muzzle axis, the plasma reached the probe at 20 μsec from the start of discharge. The first group has electron temperature and density 27 eV and 3 x 10 14 cm -3 respectively,while The second group has 25 eV and 3 x 10 14 cm -3 respectively. The decay rate of the electron temperature and density of each group is presented. The plasma radiation spectrum is detected by a dielectric filter at 3500 A degree or 6100 A degree . The experimental measurements showed that, without or with dielectric filters, the visible radiation consists from two pulses with different magnitudes within the same half cycle of discharge. The time resolution of the soft x-ray is achieved by means of scintillator detector. The detected x-ray pulse during the first half cycle of discharge had a double peaks with different structures. All the experimental results present in this paper showed that the plasma bulk propagated in the expansion chamber, consists of two-groups. 6 fig

  9. The observation on plasma endothelin levels in patients with graves' disease

    International Nuclear Information System (INIS)

    Hao Xiaojun; Liu Changshan; Yang Lianrong; Zhang Qiliang; Wang Honggang; Liu Xudong

    2002-01-01

    Observing the plasma endothelin levels in patients with Graves' disease to probe its clinical significance, plasma endothelin levels were measured in 55 cases of Graves' disease before and after treatment respectively, and these were compared with that of 23 health subjects. Results: plasma endothelin levels in patients with Graves' disease significantly increase, compared with heath subjects (150.4 +- 29.31 ng/L vs 42.80 +- 7.58 ng/L, P < 0.01); post-treatment endothelin levels apparently decrease (97.61 +- 15.99 ng/L vs 150.4 +- 29.31 ng/L, P < 0.01). Plasma endothelin levels in patients with Graves' disease significantly increase, and after treatment the endothelin levels decrease following decreasing of thyroid hormone level and high hemodynamics

  10. Observation of a Relaxed Plasma State in a Quasi-Infinite Cylinder

    Science.gov (United States)

    Gray, T.; Brown, M. R.; Dandurand, D.

    2013-02-01

    A helical relaxed plasma state is observed in a long cylindrical volume. The cylinder is long enough so that the predicted minimum energy state is a close approximation to the infinite cylinder solution. The plasma is injected at v≥50km/s by a coaxial magnetized plasma gun located at one end of the cylindrical volume. The relaxed state is rapidly attained in 1-2 axial Alfvén times after initiation of the plasma. Magnetic data are favorably compared with an analytical model. Magnetic data exhibit broadband fluctuations of the measured axial modes during the formation period. The broadband activity rapidly decays as the energy condenses into the lowest energy mode, which is in agreement with the minimum energy eigenstate of ∇×B=λB.

  11. DEMETER Observations of Equatorial Plasma Depletions and Related Ionospheric Phenomena

    Science.gov (United States)

    Berthelier, J.; Malingre, M.; Pfaff, R.; Jasperse, J.; Parrot, M.

    2008-12-01

    DEMETER, the first micro-satellite of the CNES MYRIAD program, was launched from Baikonour on June 29, 2004 on a nearly circular, quasi helio-synchronous polar orbit at ~ 715 km altitude. The DEMETER mission focuses primarily on the search for a possible coupling between seismic activity and ionospheric disturbances as well as on the effects of natural phenomena such as tropospheric thunderstorms and man-made activities on the ionosphere. The scientific payload provides fairly complete measurements of the ionospheric plasma, energetic particles above ~ 70 keV, and plasma waves, up to 20 kHz for the magnetic and 3.3 MHz for the electric components. Several studies related to space weather and ionospheric physics have been conducted over the past years. Following a brief description of the payload and the satellite modes of operation, this presentation will focus on a set of results that provide a new insight into the physics of instabilities in the night-time equatorial ionosphere. The observations were performed during the major magnetic storm of November 2004. Deep plasma depletions were observed on several night-time passes at low latitudes characterized by the decrease of the plasma density by nearly 3 orders of magnitude relative to the undisturbed plasma, and a significant abundance of molecular ions. These features can be best interpreted as resulting from the rise of the F-layer above the satellite altitude over an extended region of the ionosphere. In one of the passes, DEMETER was operated in the Burst mode and the corresponding high resolution data allowed for the discovery of two unexpected phenomena. The first one is the existence of high intensity monochromatic wave packets at the LH frequency that develop during the decay phase of intense bursts of broadband LH turbulence. The broadband LH turbulence is triggered by whistlers emitted by lightning from atmospheric thunderstorms beneath the satellite. The second unexpected feature is the detection of a

  12. Current-driven turbulence in plasmas

    International Nuclear Information System (INIS)

    Kluiver, H. de.

    1977-10-01

    Research on plasma heating in linear and toroidal systems using current-driven turbulence is reviewed. The motivation for this research is presented. Relations between parameters describing the turbulent plasma state and macroscopic observables are given. Several linear and toroidal devices used in current-driven turbulence studies are described, followed by a discussion of special diagnostic methods used. Experimental results on the measurement of electron and ion heating, anomalous plasma conductivity and associated turbulent fluctuation spectra are reviewed. Theories on current-driven turbulence are discussed and compared with experiments. It is demonstrated from the experimental results that current-driven turbulence occurs not only for extreme values of the electric field but also for an experimentally much more accessible and wide range of parameters. This forms a basis for a discussion on possible future applications in fusion-oriented plasma research

  13. Clinical and Biological Predictors of Plasma Levels of Soluble RAGE in Critically Ill Patients: Secondary Analysis of a Prospective Multicenter Observational Study

    Directory of Open Access Journals (Sweden)

    Thibaut Pranal

    2018-01-01

    Full Text Available Rationale. Although soluble forms of the receptor for advanced glycation end products (RAGE have been recently proposed as biomarkers in multiple acute or chronic diseases, few studies evaluated the influence of usual clinical and biological parameters, or of patient characteristics and comorbidities, on circulating levels of soluble RAGE in the intensive care unit (ICU setting. Objectives. To determine, among clinical and biological parameters that are usually recorded upon ICU admission, which variables, if any, could be associated with plasma levels of soluble RAGE. Methods. Data for this ancillary study were prospectively obtained from adult patients with at least one ARDS risk factor upon ICU admission enrolled in a large multicenter observational study. At ICU admission, plasma levels of total soluble RAGE (sRAGE and endogenous secretory (esRAGE were measured by duplicate ELISA and baseline patient characteristics, comorbidities, and usual clinical and biological indices were recorded. After univariate analyses, significant variables were used in multivariate, multidimensional analyses. Measurements and Main Results. 294 patients were included in this ancillary study, among whom 62% were admitted for medical reasons, including septic shock (11%, coma (11%, and pneumonia (6%. Although some variables were associated with plasma levels of RAGE soluble forms in univariate analysis, multidimensional analyses showed no significant association between admission parameters and baseline plasma sRAGE or esRAGE. Conclusions. We found no obvious association between circulating levels of soluble RAGE and clinical and biological indices that are usually recorded upon ICU admission. This trial is registered with NCT02070536.

  14. Rocket measurements within a polar cap arc - Plasma, particle, and electric circuit parameters

    Science.gov (United States)

    Weber, E. J.; Ballenthin, J. O.; Basu, S.; Carlson, H. C.; Hardy, D. A.; Maynard, N. C.; Kelley, M. C.; Fleischman, J. R.; Pfaff, R. F.

    1989-01-01

    Results are presented from the Polar Ionospheric Irregularities Experiment (PIIE), conducted from Sondrestrom, Greenland, on March 15, 1985, designed for an investigation of processes which lead to the generation of small-scale (less than 1 km) ionospheric irregularities within polar-cap F-layer auroras. An instrumented rocket was launched into a polar cap F layer aurora to measure energetic electron flux, plasma, and electric circuit parameters of a sun-aligned arc, coordinated with simultaneous measurements from the Sondrestrom incoherent scatter radar and the AFGL Airborne Ionospheric Observatory. Results indicated the existence of two different generation mechanisms on the dawnside and duskside of the arc. On the duskside, parameters are suggestive of an interchange process, while on the dawnside, fluctuation parameters are consistent with a velocity shear instability.

  15. Observation of high-temperature bubbles in an ECR plasma

    Science.gov (United States)

    Terasaka, K.; Yoshimura, S.; Tanaka, M. Y.

    2018-05-01

    Creation and annihilation of high-temperature bubbles have been observed in an electron cyclotron resonance plasma. The electron temperature in the bubble core is three times higher than that in the ambient region, and the size perpendicular to the magnetic field is much smaller than the plasma diameter. Formation of a bubble accompanies large negative spikes in the floating potential of a Langmuir probe, and the spatiotemporal behavior of the bubble has been visualized with a high-impedance wire grid detector. It is found that the bubble is in a prolate spheroidal shape with the axis along the magnetic field and occurs randomly in time and independently in space.

  16. Ulysses radio and plasma wave observations at high southern heliographic latitudes.

    Science.gov (United States)

    Stone, R G; Macdowall, R J; Fainberg, J; Kaiser, M L; Desch, M D; Goldstein, M L; Hoang, S; Bougeret, J L; Harvey, C C; Manning, R; Steinberg, J L; Kellogg, P J; Lin, N; Goetz, K; Osherovich, V A; Reiner, M J; Canu, P; Cornilleau-Wehrlin, N; Lengyel-Frey, D; Thejappa, G

    1995-05-19

    Ulysses spacecraft radio and plasma wave observations indicate that some variations in the intensity and occurrence rate of electric and magnetic wave events are functions of heliographic latitude, distance from the sun, and phase of the solar cycle. At high heliographic latitudes, solartype Ill radio emissions did not descend to the local plasma frequency, in contrast to the emission frequencies of some bursts observed in the ecliptic. Short-duration bursts of electrostatic and electromagnetic waves were often found in association with depressions in magnetic field amplitude, known as magnetic holes. Extensive wave activity observed in magnetic clouds may exist because of unusually large electron-ion temperature ratios. The lower number of intense in situ wave events at high latitudes was likely due to the decreased variability of the high- latitude solar wind.

  17. Jet quenching parameter in an expanding QCD plasma arXiv

    CERN Document Server

    Iancu, Edmond; Wu, Bin

    We study the phenomenon of transverse momentum broadening for a high-$p_T$ parton propagating through a weakly-coupled quark-gluon plasma undergoing boost-invariant longitudinal expansion. We propose a boost-invariant description for this phenomenon, in which the broadening refers to the angular variables $\\eta$ (the pseudo-rapidity) and $\\phi$ (the azimuthal angle). The jet quenching parameter $\\hat{q}$ which enters this description depends upon the proper time alone. We furthermore consider radiative corrections to $\\hat q$. As in the case of a static medium, we find potentially large corrections enhanced by a double logarithm. But unlike for the static medium, these corrections are now local in time: they depend upon the local (proper) time characterizing the expansion, and not upon the overall path length. We resum such corrections to all orders into a renormalized jet quenching parameter. The main effect of this resummation is to slow down the decrease of $\\hat q$ with increasing proper time.

  18. Effect of plasma spraying parameter on wear resistance of NiCrBSiCFe plasma coatings on austenitic stainless steel at elevated temperatures at various loads

    International Nuclear Information System (INIS)

    Parthasarathi, N.L.; Duraiselvam, Muthukannan; Borah, Utpal

    2012-01-01

    Highlights: ► Effect of plasma spraying parameters, especially the stand-off distance. ► Effect of microstructure and applied load on coating in sliding wear. ► The reason for maximum wear rate at 250 °C and the minimum wear at 350 °C were explained. ► The worn debris were characterised by SEM analysis and correlated with wear rate. -- Abstract: The dry sliding wear tests were carried out on AISI 316 austenitic stainless steel (ASS) plasma coated with NiCrBSiCFe alloy powder under two set of plasma spraying parameters (PSP-1 and PSP-2). EN 8 medium carbon steel was used as a counterface material. The tests were carried out at loads of 20 N and 40 N with a constant sliding velocity of 1 m/s at room temperature (35°), 150 °C, 250 °C and 350 °C. Metallographic characterisation was carried out by optical microscope (OM), scanning electron microscope (SEM) and X-ray diffraction (XRD). Between the two plasma parameters tested, stand-off distance of 125 mm was found to be more suitable for producing uniform lamellar microstructure with fewer amounts of pores which shows better wear resistance. The wear rate at 250 °C was comparatively more due to the material softening and adhesion by intermolecular bonding. The worn debris collected during sliding at 350 °C turn into oxides which further behaves like a protective and lubricative film eliminating the chances of severe material loss. SEM was used to characterise the worn track and debris to identity the wear mechanism.

  19. The Ionospheric Bubble Index deduced from magnetic field and plasma observations onboard Swarm

    DEFF Research Database (Denmark)

    Park, Jaeheung; Noja, Max; Stolle, Claudia

    2013-01-01

    . This product called L2-IBI is generated from magnetic field and plasma observations onboard Swarm, and gives information as to whether a Swarm magnetic field observation is affected by EPBs. We validate the performance of the L2-IBI product by using magnetic field and plasma measurements from the CHAMP...... satellite, which provided observations similar to those of the Swarm. The L2-IBI product is of interest not only for ionospheric studies, but also for geomagnetic field modeling; modelers can de-select magnetic data which are affected by EPBs or other unphysical artifacts....

  20. Observation of a relaxed plasma state in a quasi-infinite cylinder.

    Science.gov (United States)

    Gray, T; Brown, M R; Dandurand, D

    2013-02-22

    A helical relaxed plasma state is observed in a long cylindrical volume. The cylinder is long enough so that the predicted minimum energy state is a close approximation to the infinite cylinder solution. The plasma is injected at v ≥ 50 km/s by a coaxial magnetized plasma gun located at one end of the cylindrical volume. The relaxed state is rapidly attained in 1-2 axial Alfvén times after initiation of the plasma. Magnetic data are favorably compared with an analytical model. Magnetic data exhibit broadband fluctuations of the measured axial modes during the formation period. The broadband activity rapidly decays as the energy condenses into the lowest energy mode, which is in agreement with the minimum energy eigenstate of [Symbol: see text] × B = λB.

  1. Effect of the resonant magnetic perturbation on the plasma parameters in COMPASS tokamak’s divertor region

    Science.gov (United States)

    Dimitrova, M.; Cahyna, P.; Peterka, M.; Hasan, E.; Popov, Tsv K.; Ivanova, P.; Vasileva, E.; Panek, R.; Cavalier, J.; Seidl, J.; Markovic, T.; Havlicek, J.; Dejarnac, R.; Weinzettl, V.; Hacek, P.; Tomes, M.; the COMPASS Team; the EUROfusion MST1 Team

    2018-02-01

    The resonant magnetic perturbation (RMP) has proven to be a useful way to suppress edge-localized modes that under certain conditions can damage the device by the large power fluxes carried from the bulk plasma to the wall. The effect of RMP on the L-mode plasma parameters in the divertor region of the COMPASS tokamak was studied using the array of 39 Langmuir probes embedded into the divertor target. The current-voltage (IV) probe characteristics were processed by the first-derivative probe technique to obtain the plasma potential and the electron energy distribution function (EEDF) which was approximated by a bi-Maxwellian EEDF with a low-energy (4-6 eV) fraction and a high-energy (11-35 eV) one, the both factions having similar electron density. Clear splitting was observed during the RMP pulse in the low-field-side scrape-off-layer profiles of the floating potential U fl and the ion saturation current density J sat; these two quantities were obtained both by direct continuous measurement and by evaluation of the IV characteristics of probes with swept bias. The negative peaks of U fl induced by RMP spatially overlaps with the local minima of J sat (and n e) rather than with its local maxima which is partly caused by the spatial variation of the plasma potential and partly by the changed shape of the EEDF. The effective temperature of the whole EEDF is not correlated with the negative peaks of U fl, and the profile of the parallel power flux density shows secondary maxima due to RMP which mimic those of J sat.

  2. Features of highly structured equatorial plasma irregularities deduced from CHAMP observations

    Science.gov (United States)

    Xiong, C.; Lühr, H.; Ma, S. Y.; Stolle, C.; Fejer, B. G.

    2012-08-01

    In this study five years of CHAMP (Challenging Mini-satellite Payload) fluxgate magnetometer (FGM) data is used to investigate the characteristics of Equatorial Plasma Bubbles (EPBs). We filtered the FGM data by using band-passes with four different cut-off periods to get the EPBs with different maximum spatial scale sizes in the meridional plane ranging from 76-608 km. Associated with the EPB observations at about 400 km, the typical altitude of CHAMP during the year 2000-2005, we also investigate the post-sunset equatorial vertical plasma drift data from ROCSAT-1 (Republic of China Satellite 1). Since the height of the F-layer is highly correlated with the vertical plasma drift and solar flux, we sorted the ROCSAT-1 data into different groups by F10.7. From the integrated vertical drift we have estimated the post-sunset uplift of the ionosphere. By comparing the properties of EPB occurrence for different scale sizes with the global distribution of plasma vertical uplift, we have found that EPBs reaching higher altitudes are more structured than those which are sampled by CHAMP near the top side of the depleted fluxtube. Such a result is in accord with 3-D model simulations (Aveiro and Hysell, 2010). Small-scale EPB structures are observed by CHAMP when the irregularities reach apex heights of 800 km and more. Such events are encountered primarily in the Brazilian sector during the months around November, when the post-sunset vertical plasma drift is high.

  3. Dynacore Final Report , Plasma Physics prototype

    OpenAIRE

    Lourens, W.

    2000-01-01

    The generation and behaviour of plasma in a fusion device and its interaction with sur-rounding materials is studied by observing several phenomena that will accompany a plasma discharge. These phenomena are recorded by means of so called Diagnostics. These are instruments that comprise complex electronic equipment, coupled to various sensors. The generation of the plasma is also governed by electronic systems that control different parameters of the fusion device, the Tokamak, and of auxilia...

  4. Determination by R/A of plasma cortisol levels as a parameter of adrenocortical function before and after radiotherapy of gynaecological genital carcinoma

    International Nuclear Information System (INIS)

    Freischem, C.W.

    1980-01-01

    rn 20 female patients with carcinoma of the genitals, day profiles of cortisol were established and ACTH stimulation tests carried out directly after radiotherapy and 6 months later. Plasma concentrations of cortisol were determined in a RIA as parameters of the adrenocortical function. The assumption of a change in adrenocortical activity after radiotherapy of gynaecological genital carcinoma could not be validated. Instead, there was a typical diurnal rhythm of plasma cortisol, with a peak in the early morning hours and a decrease until midnight. The same applies to the ACTH stimulation tests: In all cases, plasma cortisol levels were elevated after intravenous application of ACTH. This means that the 1976 findings of Samundzham and Butsan could not be proved. Since adrenal functions were absolutely normal in the observed cases, the adynamic clinical picture of patients after radiotherapy, which is rather infrequent, cannot be explained as being due to an impaired adrenocortical function. (orig./MG) [de

  5. Study of a Laser-Produced Plasma by Langmuir Probes

    DEFF Research Database (Denmark)

    Chang, C. T.; Hasimi, M.; Pant, H. C.

    1977-01-01

    -emission peak and the main plasma from the target. The flow velocity, density and electron temperature of the plasma were determined. The expansion of the plasma was found to be adiabatic, yielding gamma =5/3. The spatial distribution of the plasma was observed to be strongly anisotropic.......The structure, the parameters and the expansion of the plasma produced by focusing a 7 J, 20 ns Nd-glass laser on stainless-steel and glass targets suspended in a high-vacuum chamber were investigated by Langmuir probes. It was observed that the probe signals consisted of a photoelectric...

  6. Some recent results from European sounding rocket and satellite observations of the hot magnetospheric plasma

    International Nuclear Information System (INIS)

    Hultqvist, B.

    1979-03-01

    A brief summary of some recent results from European studies of the hot magnetospheric plasma is presented. The material is organized in four main sections: 1) Observations of keV auroral electrons. 2) Observation of the hot ion component of the magnetospheric plasma. 3) Sudden changes of the distribution of the hot plasma in the dayside magnetosphere. 4) Banded electron cyclotron harmonic instability in the magnetosphere - a first comparison of theory and experiment. (E.R.)

  7. Observation and particle simulation of vaporized W, Mo, and Be in PISCES-B plasma for vapor-shielding studies

    Directory of Open Access Journals (Sweden)

    K. Ibano

    2017-08-01

    Full Text Available Interactions of Tungsten (W, Molybdenum (Mo, and Beryllium (Be vapors with a steady-state plasma were studied by the PISCES-B liner plasma experiments as well as Particle-In-Cell (PIC simulations for the understanding of vapor-shielding phenomena. Effective cooling of the plasma by laser-generated Be vapor was observed in PISCES-B. On the other hand, no apparent cooling was observed for W and Mo vapors. The PIC simulation explains these experimental observations of the difference between low-Z and high-Z vapors. Decrease of electron temperature due to the vapor ejection was observed in case of a simulation of the Be vapor. As for the W vapor, it was found that the plasma cooling is localized only near the wall at a higher electron density plasma (∼1019m−3. On the other hand, the appreciable plasma cooling can be observed in a lower density plasma (∼1018m−3 for the W vapor.

  8. Numerical simulation of dual frequency etching reactors: Influence of the external process parameters on the plasma characteristics

    International Nuclear Information System (INIS)

    Georgieva, V.; Bogaerts, A.

    2005-01-01

    A one-dimensional particle-in-cell/Monte Carlo model is used to investigate Ar/CF 4 /N 2 discharges sustained in capacitively coupled dual frequency reactors, with special emphasis on the influence of the reactor parameters such as applied voltage amplitudes and frequencies of the two voltage sources. The presented calculation results include plasma density, ion current, average sheath potential and width, electron and ion average energies and energy distributions, and ionization rates. The simulations were carried out for high frequencies (HFs) of 27, 40, 60, and 100 MHz and a low frequency (LF) of 1 or 2 MHz, varying the LF voltage and keeping the HF voltage constant and vice versa. It is observed that the decoupling of the two sources is possible by increasing the applied HF to very high values (above 60 MHz) and it is not defined by the frequency ratio. Both voltage sources have influence on the plasma characteristics at a HF of 27 MHz and to some extent at 40 MHz. At HFs of 60 and 100 MHz, the plasma density and ion flux are determined only by the HF voltage source. The ion energy increases and the ion energy distribution function (IEDF) becomes broader with HF or LF voltage amplitude, when the other voltage is kept constant. The IEDF is broader with the increase of HF or the decrease of LF

  9. EISCAT observations of plasma patches at sub-auroral cusp latitudes

    Directory of Open Access Journals (Sweden)

    J. Moen

    2006-09-01

    Full Text Available A sequence of 3 patches of high-density (1012 m−3 cold plasma on a horizontal scale-size of 300–700 km was observed near magnetic noon by the EISCAT VHF radar above Svalbard on 17 December 2001. The patches followed a trajectory towards the cusp inflow region. The combination of radar and all-sky observations demonstrates that the patches must have been segmented equatorward of the cusp/cleft auroral display, and hence their properties had not yet been influenced by cusp particle showers and electrodynamics on open flux tubes. The last patch in the sequence was intersected by radio tomography observations, and was found to be located adjacent to a broader region of the same high electron density further south. The patches occurred under moderately active conditions (Kp=3 and the total electron content (TEC of the high-density plasma was 45 TEC units. The train of patches appeared as a segmentation of the tongue of ionization. The sequence of patches occurred in association with a sequence of flow bursts in the dusk cell return flow. It is proposed that reconnection driven pulsed convection is able to create sub-auroral patches in the region where high density mid-latitude plasma is diverted poleward toward the cusp. It is the downward Birkeland current sheet located at the equatorward boundary of the flow disturbance that represents the actual cutting mechanism.

  10. EISCAT observations of plasma patches at sub-auroral cusp latitudes

    Directory of Open Access Journals (Sweden)

    J. Moen

    2006-09-01

    Full Text Available A sequence of 3 patches of high-density (1012 m−3 cold plasma on a horizontal scale-size of 300–700 km was observed near magnetic noon by the EISCAT VHF radar above Svalbard on 17 December 2001. The patches followed a trajectory towards the cusp inflow region. The combination of radar and all-sky observations demonstrates that the patches must have been segmented equatorward of the cusp/cleft auroral display, and hence their properties had not yet been influenced by cusp particle showers and electrodynamics on open flux tubes. The last patch in the sequence was intersected by radio tomography observations, and was found to be located adjacent to a broader region of the same high electron density further south. The patches occurred under moderately active conditions (Kp=3 and the total electron content (TEC of the high-density plasma was 45 TEC units. The train of patches appeared as a segmentation of the tongue of ionization. The sequence of patches occurred in association with a sequence of flow bursts in the dusk cell return flow. It is proposed that reconnection driven pulsed convection is able to create sub-auroral patches in the region where high density mid-latitude plasma is diverted poleward toward the cusp. It is the downward Birkeland current sheet located at the equatorward boundary of the flow disturbance that represents the actual cutting mechanism.

  11. Observation of instability-induced current redistribution in a spherical-torus plasma.

    Science.gov (United States)

    Menard, J E; Bell, R E; Gates, D A; Kaye, S M; LeBlanc, B P; Levinton, F M; Medley, S S; Sabbagh, S A; Stutman, D; Tritz, K; Yuh, H

    2006-09-01

    A motional Stark effect diagnostic has been utilized to reconstruct the parallel current density profile in a spherical-torus plasma for the first time. The measured current profile compares favorably with neoclassical theory when no large-scale magnetohydrodynamic instabilities are present in the plasma. However, a current profile anomaly is observed during saturated interchange-type instability activity. This apparent anomaly can be explained by redistribution of neutral beam injection current drive and represents the first observation of interchange-type instabilities causing such redistribution. The associated current profile modifications contribute to sustaining the central safety factor above unity for over five resistive diffusion times, and similar processes may contribute to improved operational scenarios proposed for ITER.

  12. Enhanced THz radiation generation by photo-mixing of tophat lasers in rippled density plasma with a planar magnetostatic wiggler and s-parameter

    Science.gov (United States)

    Abedi-Varaki, M.

    2018-02-01

    In this paper, the effects of planar magnetostatic wiggler and s-parameter on the terahertz (THz) radiation generation through rippled plasma have been investigated. Efficient THz radiation generation by photo-mixing of tophat lasers for rippled density plasma in the presence of the wiggler field has been presented. Fundamental equations for the analysis of the non-linear current density and THz radiation generation by wiggler magnetostatic field have been derived. It is shown that for the higher order of the tophat lasers, the values of THz amplitude are greater. In fact, the higher order of the tophat lasers has a sharp gradient in the intensity of lasers, which leads to a stronger nonlinear ponderomotive force and, consequently, a stronger current density. In addition, it is seen that by increasing s-parameter, the normalized transverse profile becomes more focused near the axis of y. Furthermore, it is observed that the normalized laser efficiency has a decreasing trend with increasing normalized THz frequency for different values of the wiggler field. Also, it is shown that by employing a greater order of the tophat lasers and a stronger wiggler field, the efficiency of order of 30% can be achieved. Moreover, it is found that we can control focus and intensity of THz radiation emitted in rippled plasma by choosing the appropriate order of the tophat lasers and tuning of the wiggler field.

  13. Observations at the planet Mercury by the plasma electron experiment, Mariner 10

    Science.gov (United States)

    Ogilvie, K. W.; Scudder, J. D.; Vasyliunas, V. M.; Hartle, R. E.; Siscoe, G. L.

    1976-01-01

    Plasma electron observations made onboard Mariner 10 are reported. Three encounters with the planet Mercury show that the planet interacts with the solar wind to form a bow shock and a permanent magnetosphere. The observations provide a determination of the dimensions and properties of the magnetosphere, independently of and in general agreement with magnetometer observations. The magnetosphere of Mercury appears to be similar in shape to that of the Earth but much smaller in relation to the size of the planet. Electron populations similar to those found in the Earth's magnetotail, within the plasma sheet and adjacent regions, were observed at Mercury; both their spatial location and the electron energy spectra within them bear qualitative and quantitative resemblance to corresponding observations at the Earth. The magnetosphere of Mercury resembles to a marked degree a reduced version of that of the Earth, with no significant differences of structure.

  14. Observations at the planet Mercury by the plasma electron experiment, Mariner 10

    International Nuclear Information System (INIS)

    Ogilvie, K.W.; Scudder, J.D.; Vasyliunas, V.M.; Hartle, R.E.; Siscoe, G.L.

    1976-09-01

    Plasma electron observations made onboard Mariner 10 are reported. Three encounters with the planet Mercury show that the planet interacts with the solar wind to form a bow shock and a permanent magnetosphere. The observations provide a determination of the dimensions and properties of the magnetosphere, independently of and in general agreement with magnetometer observations. The magnetosphere of Mercury appears to be similar in shape to that of the Earth but much smaller in relation to the size of the planet. Electron populations similar to those found in the Earth's magnetotail, within the plasma sheet and adjacent regions, were observed at Mercury; both their spatial location and the electron energy spectra within them bear qualitative and quantitative resemblance to corresponding observations at the Earth. The magnetosphere of Mercury resembles to a marked degree a reduced version of that of the Earth, with no significant differences of structure

  15. Rocket measurements within a polar cap arc: Plasma, particle, and electric circuit parameters

    International Nuclear Information System (INIS)

    Weber, E.J.; Ballenthin, J.O.; Basu, S.; Carlson, H.C.; Hardy, D.A.; Maynard, N.C.; Smiddy, M.; Kelley, M.C.; Fleischman, J.R.; Sheehan, R.E.; Pfaff, R.F.; Rodriguez, P.

    1989-01-01

    An instrumented rocket payload was launched into a polar cap F layer aurora to investigate the energetic particle, plasma, and electric circuit parameters of a Sun-aligned arc. On-board instruments measured energetic electron flux, ion composition and density fluctuations, electron density and temperature, electron density fluctuations, and ac and dc electric fields. Real-time all-sky imaging photometer measurements of the location and motion of the aurora, were used to determine the proper geophysical situation for launch. Comparison of the in situ measurements with remote optical measurements shows that the arc was produced by fluxes of low-energy (< 1 keV) electrons. Field-aligned potentials in the arc inferred from the electron spectra had a maximum value of approximately 300 V, and from the spectral shape a parent population of preaccelerated electrons characteristic of the boundary plasma sheet or magnetosheath was inferred. Electric field components along and across the arc show sunward flow within the arc and duskward drift of the arc consistent with the drift direction and speed determined from optical imaging. Thus this arc is drifting duskward under the influence of the convection electric field. Three possible explanations for this (field-aligned currents, chemistry, and transport) are considered. Finally, ionospheric irregularity and electric field fluctuations indicate two different generation mechanisms on the dawnside and duskside of the arc. On the duskside, parameters are suggestive of an interchange process, while on the dawnside, fluctuation parameters are consistent with a velocity shear instability

  16. Stability assessment and operating parameter optimization on experimental results in very small plasma focus, using sensitivity analysis

    Science.gov (United States)

    Jafari, Hossein; Habibi, Morteza

    2018-04-01

    Regarding the importance of stability in small-scale plasma focus devices for producing the repeatable and strength pinching, a sensitivity analysis approach has been used for applicability in design parameters optimization of an actually very low energy device (84 nF, 48 nH, 8-9.5 kV, ∼2.7-3.7 J). To optimize the devices functional specification, four different coaxial electrode configurations have been studied, scanning an argon gas pressure range from 0.6 to 1.5 mbar via the charging voltage variation study from 8.3 to 9.3 kV. The strength and efficient pinching was observed for the tapered anode configuration, over an expanded operating pressure range of 0.6 to 1.5 mbar. The analysis results showed that the most sensitive of the pinch voltage was associated with 0.88 ± 0.8mbar argon gas pressure and 8.3-8.5 kV charging voltage, respectively, as the optimum operating parameters. From the viewpoint of stability assessment of the device, it was observed that the least variation in stable operation of the device was for a charging voltage range of 8.3 to 8.7 kV in an operating pressure range from 0.6 to 1.1 mbar.

  17. Relationship of zinc concentrations in blood and seminal plasma with various semen parameters in infertile subjects

    International Nuclear Information System (INIS)

    Ali, H.; Ahmed, M.; Baig, M.; Ali, M.

    2007-01-01

    To find out relationship of zinc concentrations in blood and seminal plasma with various semen parameters between fertile and infertile men. (JPMC), Karachi and Department of Biochemistry. Basic Medical Sciences Institute, JPMC, Karachi. Fifty eight primary infertile male subjects, without any treatment, who had regular unprotected intercourse for at least 12 months without conception with their partners, aged 20-40 years, were selected from Infertility Clinic Jinnah Postgraduate Medical Center, Karachi. After semen analyses they were grouped as, oligospermic (30), and azoospermic (28). Twenty five known fertile male selected from general population and after semen analysis were taken as normospermic control group. Semen analyzed according to WHO criteria. Serum and seminal plasma zinc were estimated by 5Br. PAPS Colorimetric method. This study showed significant difference in serum and seminal zinc levels in normospermic, oligospermic (p<0.05) and azoospermic (p<0.005). Seminal plasma zinc showed a positive correlation with sperm count and negative with sperm motility in normospermic and oligospermic and negative correlation with volume, pH, WBC concentration in all three groups. There was no correlation found with sperm morphology. On the basis of the findings of this study and those of other reports, zinc may contribute to fertility through its significant effects on various semen parameters. It seems that the estimation of seminal plasma zinc may help in investigation and treatment of infertile males. (author)

  18. Features of highly structured equatorial plasma irregularities deduced from CHAMP observations

    Directory of Open Access Journals (Sweden)

    C. Xiong

    2012-08-01

    Full Text Available In this study five years of CHAMP (Challenging Mini-satellite Payload fluxgate magnetometer (FGM data is used to investigate the characteristics of Equatorial Plasma Bubbles (EPBs. We filtered the FGM data by using band-passes with four different cut-off periods to get the EPBs with different maximum spatial scale sizes in the meridional plane ranging from 76–608 km. Associated with the EPB observations at about 400 km, the typical altitude of CHAMP during the year 2000–2005, we also investigate the post-sunset equatorial vertical plasma drift data from ROCSAT-1 (Republic of China Satellite 1. Since the height of the F-layer is highly correlated with the vertical plasma drift and solar flux, we sorted the ROCSAT-1 data into different groups by F10.7. From the integrated vertical drift we have estimated the post-sunset uplift of the ionosphere. By comparing the properties of EPB occurrence for different scale sizes with the global distribution of plasma vertical uplift, we have found that EPBs reaching higher altitudes are more structured than those which are sampled by CHAMP near the top side of the depleted fluxtube. Such a result is in accord with 3-D model simulations (Aveiro and Hysell, 2010. Small-scale EPB structures are observed by CHAMP when the irregularities reach apex heights of 800 km and more. Such events are encountered primarily in the Brazilian sector during the months around November, when the post-sunset vertical plasma drift is high.

  19. Developing of the ionospheric plasma turbulence over the epicenters of the extremely strong earthquakes - the results of the DEMETER satellite observations

    Science.gov (United States)

    Blecki, J. S.; Parrot, M.; Wronowski, R.; Kosciesza, M.

    2011-12-01

    The DEMETER French microsatellite satellite was launched in June 2004 and finished its operation in December 2010. During the time of the DEMETER satellite operation some gigantic earthquakes took place. We will report the electromagnetic effects registered by DEMETER prior to the earthquakes with magnitude over 8 or just close to this value. We selected events with good coverage of the measurements in the burst mode when the wave form of the electric field variations were registered. It is because the special attention will be given to study of the characteristics of the spectra of these variations and search of the nonlinear effects. This analysis is possible in the time interval when the waveform has been transmitted. Using wavelet and bispectral analysis as well as the statistical characteristics of the measured parameter, we find that registered variations are associated with developing of the ionospheric plasma turbulence. It is mainly Kolmogorov type of the turbulence. The payload of the DEMETER allows to measure important plasma parameters (ion composition, electron density and temperature, energetic particles) with high temporal resolution in the ionosphere over the seismic regions. The correlation of the observed plasma turbulence with changes of the other parameters will be also given. In the present work analysis of the low frequency fluctuations of the electric and magnetic fields for the selected strong earthquakes will be given. The mechanism of the energy transmission from the earthquake to the ionosphere is not clear, but we can discuss the behavior of the ionospheric plasma and search of the instabilities which could be a source of the electromagnetic field variations. Some attempt of this discussion will be given in the presentation. We will present results obtained prior to the some giant earthquakes (Peru2007, Wechuan China 2008, Haiti 2010, Chile 2010).

  20. Performance Testing of Suspension Plasma Sprayed Thermal Barrier Coatings Produced with Varied Suspension Parameters

    Directory of Open Access Journals (Sweden)

    Nicholas Curry

    2015-07-01

    Full Text Available Suspension plasma spraying has become an emerging technology for the production of thermal barrier coatings for the gas turbine industry. Presently, though commercial systems for coating production are available, coatings remain in the development stage. Suitable suspension parameters for coating production remain an outstanding question and the influence of suspension properties on the final coatings is not well known. For this study, a number of suspensions were produced with varied solid loadings, powder size distributions and solvents. Suspensions were sprayed onto superalloy substrates coated with high velocity air fuel (HVAF -sprayed bond coats. Plasma spray parameters were selected to generate columnar structures based on previous experiments and were maintained at constant to discover the influence of the suspension behavior on coating microstructures. Testing of the produced thermal barrier coating (TBC systems has included thermal cyclic fatigue testing and thermal conductivity analysis. Pore size distribution has been characterized by mercury infiltration porosimetry. Results show a strong influence of suspension viscosity and surface tension on the microstructure of the produced coatings.

  1. Dielectric parameters of blood plasma of rats treated with cerium-144 and external irradiation

    International Nuclear Information System (INIS)

    Hadzhidekova, E.; Kiradzhiev, G.; Paskalev, Z.; Miloslavov, V.

    1988-01-01

    Investigation was carried out of the dielectric parameters of blood plasma of male Wistar rats treated with cerium 144 in doses of 370 kBq/animal and external gamma irradiation in doses of 200 cGy and 400 cGy. The radioactive cerium was introduced intraperitoneally 1 h after the external irradiation with dose rate of 1,6 cGy/sec. The permittivity ε, the time of relaxation τ and the coefficient of Debaye κ of plasma protein molecules were determined at the 1st, 3rd, 10th, 15th, and 30th days after treatement for frequence ranges of 1,4, 2,2, 3,6 and 6 MHz. At the same terms the content of cerium 144 was measured in the organs of predilectional accumulation of cerium. It was established that the treatment only with cerium lead to most essential changes of dielectric parameters at frequence of 3,6 MHz. The external irradiation didn't influence essentially the kinetics of absorbed cerium. In combination of both radiation factors the action of cerium was predominant

  2. Preparation and Characterization of Plasma-Sprayed Ultrafine Chromium Oxide Coatings

    International Nuclear Information System (INIS)

    Lin Feng; Jiang Xianliang; Yu Yueguang; Zeng Keli; Ren Xianjing; Li Zhenduo

    2007-01-01

    Ultrafine chromium oxide coatings were prepared by plasma spraying with ultrafine feedstock. Processing parameters of plasma spraying were optimized. Optical microscope (OM) was used to observe the microstructure of the ultrafine chromium oxide coatings. Scanning electron microscopy (SEM) was used to observe the morphology and particle size of ultrafine powder feedstock as well as to examine the microstructure of the chromium oxide coating. In addition, hardness and bonding strength of the ultrafine chromium oxide coatings were measured. The results showed that the optimized plasma spraying parameters were suitable for ultrafine chromium oxide coating and the properties and microstructure of the optimized ultrafine chromium oxide coating were superior compared to conventional chromium oxide wear resistant coatings

  3. Electron cyclotron resonance plasma photos

    Energy Technology Data Exchange (ETDEWEB)

    Racz, R.; Palinkas, J. [Institute of Nuclear Research (ATOMKI), H-4026 Debrecen, Bem ter 18/c (Hungary); University of Debrecen, H-4010 Debrecen, Egyetem ter 1 (Hungary); Biri, S. [Institute of Nuclear Research (ATOMKI), H-4026 Debrecen, Bem ter 18/c (Hungary)

    2010-02-15

    In order to observe and study systematically the plasma of electron cyclotron resonance (ECR) ion sources (ECRIS) we made a high number of high-resolution visible light plasma photos and movies in the ATOMKI ECRIS Laboratory. This required building the ECR ion source into an open ECR plasma device, temporarily. An 8MP digital camera was used to record photos of plasmas made from Ne, Ar, and Kr gases and from their mixtures. We studied and recorded the effect of ion source setting parameters (gas pressure, gas composition, magnetic field, and microwave power) to the shape, color, and structure of the plasma. The analysis of the photo series gave us many qualitative and numerous valuable physical information on the nature of ECR plasmas.

  4. Electron cyclotron resonance plasma photos

    International Nuclear Information System (INIS)

    Racz, R.; Palinkas, J.; Biri, S.

    2010-01-01

    In order to observe and study systematically the plasma of electron cyclotron resonance (ECR) ion sources (ECRIS) we made a high number of high-resolution visible light plasma photos and movies in the ATOMKI ECRIS Laboratory. This required building the ECR ion source into an open ECR plasma device, temporarily. An 8MP digital camera was used to record photos of plasmas made from Ne, Ar, and Kr gases and from their mixtures. We studied and recorded the effect of ion source setting parameters (gas pressure, gas composition, magnetic field, and microwave power) to the shape, color, and structure of the plasma. The analysis of the photo series gave us many qualitative and numerous valuable physical information on the nature of ECR plasmas.

  5. Experimental observation of fluid echoes in a non-neutral plasma

    International Nuclear Information System (INIS)

    Yu, Jonathan H.; Driscoll, C. Fred

    2002-01-01

    Experimental observation of a nonlinear fluid echo is presented which demonstrates the reversible nature of spatial Landau damping, and that non-neutral plasmas behave as nearly ideal 2D fluids. These experiments are performed on UCSD's CamV Penning-Malmberg trap with magnetized electron plasmas. An initial m i =2 diocotron wave is excited, and the received wall signal damps away in about 5 wave periods. The density perturbation filaments are observed to wrap up as the wave is spatially Landau damped. An m t =4 'tickler' wave is then excited, and this wave also Landau damps. The echo consists of a spontaneous appearance of a third m e =2 wave after the responses to the first two waves have inviscidly damped away. The appearance time of the echo agrees with theory, and data suggests the echo is destroyed at least partly due to saturation

  6. Dynamics of imploding argon plasmas

    International Nuclear Information System (INIS)

    Clark, W.; Richardson, R.; Brannon, J.; Wilkinson, M.; Katzenstein, J.

    1982-01-01

    The BLACKJACK 5 pulse generator has been used to implode annular argon plasmas to form dense Z pinches. Visible streak photography, framing photography, and laser shadowgraphy were used to observe the radial position and velocity of the plasmas as they imploded. The measured position and velocity of the imploding plasmas have been compared with the results of calculations based on a one-dimensional snowplow model. Good agreement is obtained between the snowplow calculations and the optical measurements. Empirically determined optimum implosion parameters are also found to agree with those predicted by the model

  7. Spatial diagnostics of the laser induced lithium fluoride plasma

    Energy Technology Data Exchange (ETDEWEB)

    Baig, M. A.; Qamar, Aisha; Fareed, M. A.; Anwar-ul-Haq, M.; Ali, Raheel [Atomic and Molecular Physics Laboratory, Department of Physics, Quaid-i-Azam University, 45320 Islamabad (Pakistan)

    2012-06-15

    We present spatial characteristics of the lithium fluoride plasma generated by the fundamental and second harmonic of a Nd:YAG laser. The plume emission has been recorded spatially using five spectrometers covering the spectral region from 200 nm to 720 nm. The electron density is measured from the Stark broadened line profile of the line at 610.37 nm, whereas the plasma temperature has been determined using the Boltzmann plot method including all the observed spectral lines of lithium. Both the plasma parameters; electron density and plasma temperature decrease with the increase of the distance from the target surface. The thermal conduction towards the target, the radiative cooling of the plasma, and the conversion of thermal energy into kinetic energy are the main mechanisms responsible for the spatially decrease of the plasma parameters.

  8. Basic Earth's Parameters as estimated from VLBI observations

    Directory of Open Access Journals (Sweden)

    Ping Zhu

    2017-11-01

    Full Text Available The global Very Long Baseline Interferometry observation for measuring the Earth rotation's parameters was launched around 1970s. Since then the precision of the measurements is continuously improving by taking into account various instrumental and environmental effects. The MHB2000 nutation model was introduced in 2002, which is constructed based on a revised nutation series derived from 20 years VLBI observations (1980–1999. In this work, we firstly estimated the amplitudes of all nutation terms from the IERS-EOP-C04 VLBI global solutions w.r.t. IAU1980, then we further inferred the BEPs (Basic Earth's Parameters by fitting the major nutation terms. Meanwhile, the BEPs were obtained from the same nutation time series using a BI (Bayesian Inversion. The corrections to the precession rate and the estimated BEPs are in an agreement, independent of which methods have been applied.

  9. Surface temperature: A key parameter to control the propanethiol plasma polymer chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Thiry, Damien, E-mail: damien.thiry@umons.ac.be; Aparicio, Francisco J. [Chimie des Interactions Plasma Surface (ChIPS), CIRMAP, Université de Mons, 23 Place du Parc, B-7000 Mons (Belgium); Laha, Priya; Terryn, Herman [Research Group Electrochemical and Surface Engineering (SURF), Department of Materials and Chemistry (MACH), Pleinlaan 2, 1050 Brussel (Belgium); Snyders, Rony [Chimie des Interactions Plasma Surface (ChIPS), CIRMAP, Université de Mons, 23 Place du Parc, B-7000 Mons, Belgium and Materia Nova Research Center, Parc Initialis, B-7000 Mons (Belgium)

    2014-09-01

    In this work, the influence of the substrate temperature (T{sub s}) on the chemical composition of propanethiol plasma polymers was investigated for a given set of plasma conditions. In a first study, a decrease in the atomic sulfur content (at. %S) with the deposition time (t{sub d}) was observed. This behavior is explained by the heating of the growing film during deposition process, limiting the incorporation of stable sulfur-based molecules produced in the plasma. Experiments carried out by controlling the substrate temperature support this hypothesis. On the other hand, an empirical law relating the T{sub s} and the at. %S was established. This allows for the formation of gradient layer presenting a heterogeneous chemical composition along the thickness, as determined by depth profile analysis combining X-ray photoelectron spectroscopy and C{sub 60} ion gun sputtering. The experimental data fit with the one predicted from our empiric description. The whole set of our results provide new insights in the relationship between the substrate temperature and the sulfur content in sulfur-based plasma polymers, essential for future developments.

  10. Full Two-Body Problem Mass Parameter Observability Explored Through Doubly Synchronous Systems

    Science.gov (United States)

    Davis, Alex Benjamin; Scheeres, Daniel

    2018-04-01

    The full two-body problem (F2BP) is often used to model binary asteroid systems, representing the bodies as two finite mass distributions whose dynamics are influenced by their mutual gravity potential. The emergent behavior of the F2BP is highly coupled translational and rotational mutual motion of the mass distributions. For these systems the doubly synchronous equilibrium occurs when both bodies are tidally-locked and in a circular co-orbit. Stable oscillations about this equilibrium can be shown, for the nonplanar system, to be combinations of seven fundamental frequencies of the system and the mutual orbit rate. The fundamental frequencies arise as the linear periods of center manifolds identified about the equilibrium which are heavily influenced by each body’s mass parameters. We leverage these eight dynamical constraints to investigate the observability of binary asteroid mass parameters via dynamical observations. This is accomplished by proving the nonsingularity of the relationship between the frequencies and mass parameters for doubly synchronous systems. Thus we can invert the relationship to show that given observations of the frequencies, we can solve for the mass parameters of a target system. In so doing we are able to predict the estimation covariance of the mass parameters based on observation quality and define necessary observation accuracies for desired mass parameter certainties. We apply these tools to 617 Patroclus, a doubly synchronous Trojan binary and flyby target of the LUCY mission, as well as the Pluto and Charon system in order to predict mutual behaviors of these doubly synchronous systems and to provide observational requirements for these systems’ mass parameters

  11. Observation of minor collapse of current-carrying plasma in LHD

    International Nuclear Information System (INIS)

    Narushima, Yoshiro; Sakakibara, Satoru; Watanabe, Kiyomasa

    2006-01-01

    A minor collapse observed in current-carrying plasma has been investigated in Large Helical Device (LHD). The magnetic configuration with high central rotational transform has ι/2π=1 surface at the core region and is relatively unstable for the m/n=1/1 mode (here, m and n are the poloidal and toroidal mode number, respectively). When the beam-driven current exceeds a certain value, the m/n=1/1 mode grows with a growth time of ∼30 ms and causes a sudden drop of the plasma stored energy and the electron temperature, and it also limits the plasma current itself. A local flattening in an electron temperature profile appears just after the minor collapse. The mode does not rotate and stays at the same spatial location. The possibility of pressure- and current-driven magneto-hydro dynamics (MHD) instabilities is discussed. (author)

  12. The ASDEX Upgrade Parameter Server

    Energy Technology Data Exchange (ETDEWEB)

    Neu, Gregor, E-mail: gregor.neu@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Cole, Richard [Unlimited Computer Systems, Seeshaupter Str. 15, 82393 Iffeldorf (Germany); Gräter, Alex [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Lüddecke, Klaus [Unlimited Computer Systems, Seeshaupter Str. 15, 82393 Iffeldorf (Germany); Rapson, Christopher J.; Raupp, Gerhard; Treutterer, Wolfgang; Zasche, Dietrich; Zehetbauer, Thomas [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany)

    2015-10-15

    Highlights: • We describe our main tool in the plasma control configuration process. • Parameter access and computation are configurable with XML files. • Simple implementation of in situ tests by rerouting requests to test data. • Pulse specific overriding of parameters. - Abstract: Concepts for the configuration of plant systems and plasma control of modern devices such as ITER and W7-X are based on global data structures, or “pulse schedules” or “experiment programs”, which specify all physics characteristics (waveforms for controlled actuators and plasma quantities) and all technical characteristics of the plant systems (diagnostics and actuators operation settings) for a planned pulse. At ASDEX Upgrade we use different approach. We observed that the physics characteristics driving the discharge control system (DCS) are frequently modified on a pulse-to-pulse basis. Plant system operation, however, relies on technical standard settings, or “basic configurations” to provide guaranteed resources or services, which evolve according to longer term session or campaign operation schedules. This is why AUG manages technical configuration items separately from physics items. Consistent computation of the DCS configuration requires access to all this physics and technical data, which include the discharge programme (DP), settings of actuator systems and real-time diagnostics, the current system state and a database of static parameters. A Parameter Server provides a unified view on all these parameter sets and acts as the central point of access. We describe the functionality and architecture of the Parameter Server and its embedding into the control environment.

  13. Recent observations of beam plasma interactions in the ionosphere and a comparison with laboratory studies of the beam plasma discharge

    International Nuclear Information System (INIS)

    Bernstein, W.; Holzworth, R.H.; Kellogg, P.J.; Monson, S.J.; Whalen, B.A.

    1982-01-01

    This chapter summarizes the experimental results which relate to collective beam-plasma interactions from a recent electron beam injection rocket flight launched into an active aurora. NASA rocket 27:010 AE carried a modest accelerator which injected programmed electron beams of <100 ma at 2 and 4 kV into the ionosphere plasma over the altitude range 120-240 km. Topics considered include a description of the payloads, accelerator operation, diagnostics (aft section, aft payload geometric configuration, wave diagnostics, TAD instrumentation), experimental results (161 eV-20 KeV electrons, thermal ions, TAD data, wave measurements), and laboratory results (energetic particles, photometric observations). A major objective of this experiment was the possible identification of the ignition of the Beam-Plasma Discharge (BPD) which has been intensively studied in laboratory configurations. The results indicate that BPD ignition occurred for Im current pulses at 2 and 4 kV and during the 3 kHz modulation period. It is concluded that many of the observed characteristics are similar to the BPD characteristics observed in the laboratory

  14. A Study of Charge-Exchange Neutrals from a Rotating Plasma

    DEFF Research Database (Denmark)

    Jørgensen, L. W.; Sillesen, Alfred Hegaard

    1980-01-01

    Measurements of charge-exchange neutrals leaving a rotating plasma (a puffatron device) are reported. Neutrals are observed only during the breakdown phase (2-3 mu s) indicating that the created plasma is fully ionized. Several energy spectra of the neutrals for different plasma parameters are ob....... Neutral particle measurements at different distances from the puffatron midplane show ionization velocities parallel with the magnetic field of about 2*104 ms-1 and plasma expansion velocities of about 5-6*104 ms-1 corresponding to an electron temperature of about 25 eV.......Measurements of charge-exchange neutrals leaving a rotating plasma (a puffatron device) are reported. Neutrals are observed only during the breakdown phase (2-3 mu s) indicating that the created plasma is fully ionized. Several energy spectra of the neutrals for different plasma parameters...... are obtained. These spectra are grossly explained using a single-particle orbit model of the plasma ions. Assuming a Maxwellian distribution for the spread in the ion Larmor energy for the central part of the measured energy spectra, it is possible to determine the ion energy during the breakdown phase...

  15. Plasma sheath dynamics and parameters in focus and defocus conditions. Vol. 2

    International Nuclear Information System (INIS)

    Masoud, M.M.; Soliman, H.M.; El-Aragi, G.M.

    1996-01-01

    The study deals with the effect of the inner electrode polarity on the dynamic behaviour and parameters of plasma sheath in a coaxial discharge. The experimental investigations presented here were carried out in a coaxial plasma focus discharge device of mather geometry. It consisted of coaxial stainless steel hollow cylindrical electrodes with inner electrode 18.2 cm length and outer-electrode 31.5 cm length. The diameter of the inner and outer electrodes are 3.2 cm and 6.6 cm, respectively. The two electrodes are separated by a teflon disc at the breech. The outer electrode muzzle is connected to stainless steel expansion chamber of 23 cm length and 17 cm diameter. The discharge takes place in hydrogen gas with a base pressure of 1 torr. The experiments were conducted with 10 kV bank voltage, which corresponds to 100 K A peak discharge current. By using a double electric probe, It was found that the plasma electron density was higher near the negative electrode. Investigations using a miniature rogovsky coil have shown that, the radial and azimuthal current density increased with radial distance from negative electrode to positive electrode. The shape and the axial velocity of plasma sheath were measured using a magnetic probe. The experimental results indicate that, the plasma is thick near the negative electrode, in both cases of the outer or the inner electrode. Also it has been found that the axial plasma sheath velocity reaches its maximum value at the muzzle for positive and negative inner electrode. The magnitude of maximum axial velocity reaches 1.7 x 10 60 cm/s for positive inner electrode and decreased by 25% for negative inner electrode further investigations revealed that on interchanging the polarity from normal operation (positive inner electrode), it was found that with negative inner electrode the soft x-ray emission intensity dropped by three orders of magnitude from that with positive inner electrode. 9 figs

  16. Plasma sheath dynamics and parameters in focus and defocus conditions. Vol. 2

    Energy Technology Data Exchange (ETDEWEB)

    Masoud, M M; Soliman, H M; El-Aragi, G M [Plasma Physics and Nuclear Fusion Department, Nuclear Research Centre, Atomic Energy Aurhority, Cairo (Egypt)

    1996-03-01

    The study deals with the effect of the inner electrode polarity on the dynamic behaviour and parameters of plasma sheath in a coaxial discharge. The experimental investigations presented here were carried out in a coaxial plasma focus discharge device of mather geometry. It consisted of coaxial stainless steel hollow cylindrical electrodes with inner electrode 18.2 cm length and outer-electrode 31.5 cm length. The diameter of the inner and outer electrodes are 3.2 cm and 6.6 cm, respectively. The two electrodes are separated by a teflon disc at the breech. The outer electrode muzzle is connected to stainless steel expansion chamber of 23 cm length and 17 cm diameter. The discharge takes place in hydrogen gas with a base pressure of 1 torr. The experiments were conducted with 10 kV bank voltage, which corresponds to 100 K A peak discharge current. By using a double electric probe, It was found that the plasma electron density was higher near the negative electrode. Investigations using a miniature rogovsky coil have shown that, the radial and azimuthal current density increased with radial distance from negative electrode to positive electrode. The shape and the axial velocity of plasma sheath were measured using a magnetic probe. The experimental results indicate that, the plasma is thick near the negative electrode, in both cases of the outer or the inner electrode. Also it has been found that the axial plasma sheath velocity reaches its maximum value at the muzzle for positive and negative inner electrode. The magnitude of maximum axial velocity reaches 1.7 x 10{sup 60} cm/s for positive inner electrode and decreased by 25% for negative inner electrode further investigations revealed that on interchanging the polarity from normal operation (positive inner electrode), it was found that with negative inner electrode the soft x-ray emission intensity dropped by three orders of magnitude from that with positive inner electrode. 9 figs.

  17. Observations of imposed ordered structures in a dusty plasma at high magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Edward, E-mail: etjr@auburn.edu; Lynch, Brian; Konopka, Uwe [Physics Department, Auburn University, Auburn, Alabama 36849 (United States); Merlino, Robert L. [Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242 (United States); Rosenberg, Marlene [Department of Electrical and Computer Engineering, University of California–San Diego, La Jolla, California 92093 (United States)

    2015-03-15

    Dusty plasmas have been studied in argon, rf glow discharge plasmas at magnetic fields up to 2 T, where the electrons and ions are strongly magnetized. In this experiment, plasmas are generated between two parallel plate electrodes where the lower, powered electrode is solid and the upper, electrically floating electrode supports a semi-transparent, titanium mesh. We report on the formation of an ordered dusty plasma, where the dust particles form a spatial structure that is aligned to the mesh. We discuss possible mechanisms that may lead to the formation of the “dust grid” and point out potential implications and applications of these observations.

  18. Edge transport barrier modification in the L-2M stellarator depending on the heating power and plasma parameters

    International Nuclear Information System (INIS)

    Voronov, G S; Voronova, E V; Akulina, D K; Gladkov, G A

    2006-01-01

    Boronization of the vacuum chamber of the L-2M stellarator has resulted in modification of the electron temperature profile. In particular, a well-defined jump in the electron temperature to T e ∼ 100 eV in a narrow region Δr/r ∼ 0.05 is observed in the temperature profile at the plasma edge. In the present paper, the value and shape of the jump in T e are studied at different values of plasma parameters and ECR heating power. A jump in T e is absent at a power of P ∼ 100 kW, whereas at P ∼ 200 kW the electron temperature drops from 150 eV to zero within Δr ∼ 0.5 cm. The value of threshold power for the formation of a jump in T e at n e ∼ 1.7 x 10 19 m -3 lies within the range P ∼ 100-160 kW. In terms of power per particle this power threshold is P/V/N e ∼ 0.2-0.3 Mw/m 3 /10 19 m -3 , the value of which coincides with threshold power for ETB formation found recently in the CHS stellarator. When the helical-field strength is 25% or 50% below its standard value, a jump in T e at the plasma edge in L-2M is absent

  19. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Spectroscopic investigation of thermodynamic parameters of a plasma plume formed by the action of cw CO2 laser radiation on a metal substrate

    Science.gov (United States)

    Vasil'chenko, Zh V.; Azharonok, V. V.; Filatova, I. I.; Shimanovich, V. D.; Golubev, V. S.; Zabelin, A. M.

    1996-09-01

    Emission spectroscopy methods were used in an investigation of thermodynamic parameters of a surface plasma formed by the action of cw CO2 laser radiation of (2-5)×106 W cm-2 intensity on stainless steel in a protective He or Ar atmosphere. The spatiotemporal structure and pulsation characteristics of the plasma plume were used to determine the fields of the plasma electron density and temperature.

  20. The effect of processing parameters on plasma sprayed beryllium for fusion applications

    International Nuclear Information System (INIS)

    Castro, R.G.; Stanek, P.W.; Jacobson, L.A.; Cowgill, D.F.; Snead, L.L.

    1993-01-01

    Plasma spraying is being investigated as a potential coating technique for applying thin (0.1--5mm) layers of beryllium on plasma facing surfaces of blanket modules in ITER and also as an in-situ repair technique for repairing eroded beryllium surfaces in high heat flux divertor regions. High density spray deposits (>98% of theoretical density) of beryllium will be required in order to maximize the thermal conductivity of the beryllium coatings. A preliminary investigation was done to determine the effect of various processing parameters (particle size, particle morphology, secondary gas additions and reduced chamber pressure) on the as-deposited density of beryllium. The deposits were made using spherical beryllium feedstock powder which was produced by centrifugal atomization at Los Alamos National Laboratory (LANL). Improvements in the as-deposited densities and deposit efficiencies of the beryllium spray deposits will be discussed along with the corresponding thermal conductivity and outgassing behavior of these deposits

  1. The effect of processing parameters on plasma sprayed beryllium for fusion applications

    International Nuclear Information System (INIS)

    Castro, R.G.; Stanek, P.W.; Jacobson, L.W.; Cowgill, D.F.

    1993-01-01

    Plasma spraying is being investigated as a potential coating technique for applying thin (0.1-5mm) layers of beryllium on plasma facing surfaces of blanket modules in ITER and also as an in-situ repair technique for repairing eroded beryllium surfaces in high heat flux divertor regions. High density spray deposits (>98% of theoretical density) of beryllium will be required in order to maximize the thermal conductivity of the beryllium coatings. A preliminary investigation was done to determine the effect of various processing parameters (particle size, particle morphology, secondary gas additions and reduced chamber pressure) on the as-deposited density of beryllium. The deposits were made using spherical beryllium feedstock powder which was produced by centrifugal atomization at Los Alamos National Laboratory (LANL). Improvements in the as-deposited densities and deposit efficiencies of the beryllium spray deposits will be discussed along with the corresponding thermal conductivity and outgassing behavior of these deposits. (orig.)

  2. Spectroscopic observations in the visible and near ultraviolet of a laser-produced plasma

    International Nuclear Information System (INIS)

    Zago, A.; Tondello, G.

    1985-01-01

    The emission from a plasma produced by laser focusing on plane targets of the elements Be, B, C and N has been observed in the visible and near ultraviolet. The spectra have been recorded mainly with an optical multichannel analyser allowing great sensitivity of detection. Both continua and line emission have been analysed in terms of plasma properties. Very broad lines of the type Δn = 1 appear prominent in the spectrum and, through their Stark broadening, the electron density of the plasma has been derived

  3. Spectroscopic observations in the visible and near ultraviolet of a laser-produced plasma

    Energy Technology Data Exchange (ETDEWEB)

    Zago, A.; Tondello, G.

    1985-01-11

    The emission from a plasma produced by laser focusing on plane targets of the elements Be, B, C and N has been observed in the visible and near ultraviolet. The spectra have been recorded mainly with an optical multichannel analyser allowing great sensitivity of detection. Both continua and line emission have been analysed in terms of plasma properties. Very broad lines of the type ..delta..n = 1 appear prominent in the spectrum and, through their Stark broadening, the electron density of the plasma has been derived.

  4. Interrelated experiments in laboratory and space plasmas

    International Nuclear Information System (INIS)

    Koepke, M. E.

    2005-01-01

    Many advances in understanding space plasma phenomena have been linked to insight derived from theoretical modelling and/or laboratory experiments. Here are discussed advances for which laboratory experiments played an important role. How the interpretation of the space plasma data was influenced by one or more laboratory experiments is described. The space-motivation of laboratory investigations and the scaling of laboratory plasma parameters to space plasma conditions are discussed. Examples demonstrating how laboratory experiments develop physical insight, benchmark theoretical models, discover unexpected behaviour, establish observational signatures, and pioneer diagnostic methods for the space community are presented. The various device configurations found in space-related laboratory investigations are outlined. A primary objective of this review is to articulate the overlapping scientific issues that are addressable in space and lab experiments. A secondary objective is to convey the wide range of laboratory and space plasma experiments involved in this interdisciplinary alliance. The interrelation ship between plasma experiments in the laboratory and in space has a long history, with numerous demonstrations of the benefits afforded the space community by laboratory results. An experiment's suitability and limitations for investigating space processes can be quantitatively established using dimensionless parameters. Even with a partial match of these parameters, aspects of waves, instabilities, nonlinearities, particle transport, reconnection, and hydrodynamics are addressable in a way useful to observers and modelers of space phenomena. Because diagnostic access to space plasmas, laboratory-experimentalists awareness of space phenomena, and efforts by theorists and funding agencies to help scientists bridge the gap between the space and laboratory communities are increasing, the range of laboratory and space plasma experiments with overlapping scientific

  5. Theoretical search for optimal pump parameters for observing spontaneous radiation amplification on the λ=41.8-nm transition of Xe IX in plasma

    International Nuclear Information System (INIS)

    Ivanova, E P; Ivanov, Arkadii L

    2004-01-01

    Based on a collisional-radiative model, an atomic-kinetic calculation of the gains on the 41.8-nm transitions of Pd-like xenon was performed for the plasma produced due to the interaction of a femtosecond laser pulse with gaseous xenon. The gains g(z,τ) averaged over the spatial and temporal coordinates were compared with the known gains which had been measured experimentally in Xe 8+ . The amplification was shown to occur under the conditions of ionisation of the working ions, and the time of output radiation saturation depends on the time of Xe 8+ transformation to higher-ionised ions. Our theoretical investigation enables determining the optimal pump parameters, at which the product of the gain g by the active medium length L is about 20, which exceeds the experimental gL value. (active media)

  6. Effects of magnesium on erythrocyte sodium-lithium countertransport and some of plasma biochemical parameters in rabbit

    Directory of Open Access Journals (Sweden)

    Samad Akbarzadeh

    2009-02-01

    Full Text Available Background: Magnesium acts as an essential cofactor for the activity of many enzymes. It regulates the work of cardiovascular system. The activity of sodium–lithium countertransport (SLC and the concentrations of plasma biochemical parameters such as VLDL, LDL-cholesterol, HDL-cholesterol, sodium, potassium, urea and creatinine are changed in cardiovascular diseases. The aim of this study was to determine the effects of magnesium on SLC activity and some of the plasma biochemical parameters. Methods: New Zealand white rabbits (weighed 1350 ± 50g were chosen for these experiments. This study was conducted through two in vitro and in vivo techniques. Through in vitro method, the effects of different concentrations of magnesium on SLC activity were investigated. In order to conduct in vivo method, the rabbits were divided into two groups (5 /group. One group was treated by MgSo4 (40 mg/kg body weight through peritoneum for two weeks. For the second group, deionized water was used. The activity of SLC and mentioned biochemical parameters were determined. Results: The results of both in vitro and in vivo studies showed that magnesium can significantly decrease the SLC activity and also causes an increase in Km and decreased Vmax/Km of the system and plasma concentrations of VLDL, LDL-cholesterol, total cholesterol and triglycerides were significantly decreased. Conclusion: Magnesium may cause a reduction in blood pressure through decreasing the SLC activity and affecting the concentrations of VLDL, LDL-cholesterol, total cholesterol and triglycerides and so improvement the cardiovascular diseases.

  7. PARAMETER ESTIMATION AND MODEL SELECTION FOR INDOOR ENVIRONMENTS BASED ON SPARSE OBSERVATIONS

    Directory of Open Access Journals (Sweden)

    Y. Dehbi

    2017-09-01

    Full Text Available This paper presents a novel method for the parameter estimation and model selection for the reconstruction of indoor environments based on sparse observations. While most approaches for the reconstruction of indoor models rely on dense observations, we predict scenes of the interior with high accuracy in the absence of indoor measurements. We use a model-based top-down approach and incorporate strong but profound prior knowledge. The latter includes probability density functions for model parameters and sparse observations such as room areas and the building footprint. The floorplan model is characterized by linear and bi-linear relations with discrete and continuous parameters. We focus on the stochastic estimation of model parameters based on a topological model derived by combinatorial reasoning in a first step. A Gauss-Markov model is applied for estimation and simulation of the model parameters. Symmetries are represented and exploited during the estimation process. Background knowledge as well as observations are incorporated in a maximum likelihood estimation and model selection is performed with AIC/BIC. The likelihood is also used for the detection and correction of potential errors in the topological model. Estimation results are presented and discussed.

  8. Parameter Estimation and Model Selection for Indoor Environments Based on Sparse Observations

    Science.gov (United States)

    Dehbi, Y.; Loch-Dehbi, S.; Plümer, L.

    2017-09-01

    This paper presents a novel method for the parameter estimation and model selection for the reconstruction of indoor environments based on sparse observations. While most approaches for the reconstruction of indoor models rely on dense observations, we predict scenes of the interior with high accuracy in the absence of indoor measurements. We use a model-based top-down approach and incorporate strong but profound prior knowledge. The latter includes probability density functions for model parameters and sparse observations such as room areas and the building footprint. The floorplan model is characterized by linear and bi-linear relations with discrete and continuous parameters. We focus on the stochastic estimation of model parameters based on a topological model derived by combinatorial reasoning in a first step. A Gauss-Markov model is applied for estimation and simulation of the model parameters. Symmetries are represented and exploited during the estimation process. Background knowledge as well as observations are incorporated in a maximum likelihood estimation and model selection is performed with AIC/BIC. The likelihood is also used for the detection and correction of potential errors in the topological model. Estimation results are presented and discussed.

  9. Instabilities observed at the bubble edge of a laser produced plasma during its expansion in an ambient tenuous plasma

    Science.gov (United States)

    Lee, Bo Ram; Clark, S. E.; Hoffmann, D. H. H.; Niemann, C.

    2014-10-01

    The Raptor kJ class 1053 nm Nd:Glass laser in the Phoenix laser laboratory at University of California, Los Angeles, is used to ablate a dense debris plasma from a graphite or plastic target embedded in a tenuous, uniform, and quiescent ambient magnetized plasma in the Large Plasma Device (LAPD) which provides a peak plasma density of ni ~ 1013 cm-3. Its background magnetic field can vary between 200 and 1200 G. Debris ions from laser produced plasma expand out conically with super-Alfvénic speed (MA ~ 2) and expel the background magnetic field and ambient ions to form a diamagnetic bubble. The debris plasma interacts with the ambient plasma and the magnetic field and acts as a piston which can create collisionless shocks. Flute-type instabilities, which are probably large Larmor radius Rayleigh Taylor instabilities or lower hybrid drift instabilities, are developed at the bubble edge and also observed in the experiment. The amplitude and wavelength dependence of the instabilities, which might be a strong function of debris to ambient mass to charge ratio, is studied and the experimental results are compared to the two dimensional hybrid simulations. the Deutsche Forschungsgemeinschaft in the framework of the Excellence Initiative Darmstadt Graduate School of Energy Science and Engineering (GSC1070).

  10. Evaluation of hemostasis parameters and the role of the oxidative damage to plasma proteins in the modulation of hemostasis in patients with nephrolithiasis before and after extracorporeal shock wave lithotripsy.

    Directory of Open Access Journals (Sweden)

    Paweł Woźniak

    Full Text Available Extracorporeal shock wave lithotripsy (ESWL is a commonly-used method in urology, which may modulate hemostasis and may induce lipid peroxidation in patients with nephrolithiasis. However, previous studies only examine changes occurring in patients 30-240 min after ESWL. The main aim of the present study was to determine whether oxidative stress may modulate the hemostatic activity of plasma in patients with nephrolithiasis before ESWL and the day after treatment ESWL. This will be performed by measuring selected parameters of hemostasis in these patients, both before ESWL and the following day, and assessing the level of oxidative damage to plasma proteins in these patients by measuring two biomarkers.Twelve patients with nephrolithiasis and 10 healthy participants were included. The following parameters of hemostasis were measured: the activated partial thromboplastin time (APTT, prothrombin time (PT, and thrombin time (TT of plasma, the level of fibrinogen, the level of D-dimer and blood platelet count. In addition, two selected biomarkers of oxidative stress were measured: protein carbonylation level and the number of protein thiol groups.No difference was observed between patients with nephrolithiasis before and after ESWL and healthy controls with regard to PT, TT or APTT. Fibrinogen concentration and blood platelet count were lower in the nephrolithiasis patients in the period after ESWL than before ESWL. The nephrolithiasis patients demonstrated elevated D-dimer concentration after ESWL. However, although oxidative damage was observed in the plasma proteins in the nephrolithiasis patients, this was not influenced by ESWL.Oxidative stress may induce changes of hemostasis in patients with nephrolithiasis, both before and after ESWL. In addition, changes of hemostasis parameters such as fibrinogen, blood platelet count and D-dimer level can be observed in these patients, especially after ESWL, and this may suggest that ESWL modulates

  11. Evaluation of hemostasis parameters and the role of the oxidative damage to plasma proteins in the modulation of hemostasis in patients with nephrolithiasis before and after extracorporeal shock wave lithotripsy.

    Science.gov (United States)

    Woźniak, Paweł; Kontek, Bogdan; Różański, Waldemar; Olas, Beata

    2017-01-01

    Extracorporeal shock wave lithotripsy (ESWL) is a commonly-used method in urology, which may modulate hemostasis and may induce lipid peroxidation in patients with nephrolithiasis. However, previous studies only examine changes occurring in patients 30-240 min after ESWL. The main aim of the present study was to determine whether oxidative stress may modulate the hemostatic activity of plasma in patients with nephrolithiasis before ESWL and the day after treatment ESWL. This will be performed by measuring selected parameters of hemostasis in these patients, both before ESWL and the following day, and assessing the level of oxidative damage to plasma proteins in these patients by measuring two biomarkers. Twelve patients with nephrolithiasis and 10 healthy participants were included. The following parameters of hemostasis were measured: the activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) of plasma, the level of fibrinogen, the level of D-dimer and blood platelet count. In addition, two selected biomarkers of oxidative stress were measured: protein carbonylation level and the number of protein thiol groups. No difference was observed between patients with nephrolithiasis before and after ESWL and healthy controls with regard to PT, TT or APTT. Fibrinogen concentration and blood platelet count were lower in the nephrolithiasis patients in the period after ESWL than before ESWL. The nephrolithiasis patients demonstrated elevated D-dimer concentration after ESWL. However, although oxidative damage was observed in the plasma proteins in the nephrolithiasis patients, this was not influenced by ESWL. Oxidative stress may induce changes of hemostasis in patients with nephrolithiasis, both before and after ESWL. In addition, changes of hemostasis parameters such as fibrinogen, blood platelet count and D-dimer level can be observed in these patients, especially after ESWL, and this may suggest that ESWL modulates hemostasis. By

  12. Plasma spray technology process parameters and applications

    International Nuclear Information System (INIS)

    Sreekumar, K.P.; Karthikeyan, J.; Ananthapadmanabhan, P.V.; Venkatramani, N.; Chatterjee, U.K.

    1991-01-01

    The current trend in the structural design philosophy is based on the use of substrate with the necessary mechanical properties and a thin coating to exhibit surface properties. Plasma spray process is a versatile surface coating technique which finds extensive application in meeting advance technologies. This report describes the plasma spray technique and its use in developing coatings for various applications. The spray system is desribed in detail including the different variables such as power input to the torch, gas flow rate, powder properties, powder injection, etc. and their interrelation in deciding the quality of the coating. A brief write-up on the various plasma spray coatings developed for different applications is also included. (author). 15 refs., 15 figs., 2 tabs

  13. Plasma Immersion Ion Implantation in Radio Frequency Plasma

    International Nuclear Information System (INIS)

    Bora, B.; Bhuyan, H.; Wyndham, E.

    2013-01-01

    Plasma immersion ion implantation (PIII) has attracted wide interests since it emulates conventional ion-beam ion implantation (IBII) in niche applications. For instance, the technique has very high throughput, the implantation time is independent of the sample size, and samples with an irregular shape can be implanted without complex beam scanning or sample manipulation. For uniform ion implantation and deposition on to different substrates, like silicon, stainless steel etc., a capacitive coupled Radio frequency (RF), 13.6 MHz, plasma is used. During the PIII process, the physical parameters which are expected to play crucial rule in the deposition process like RF power, Negative pulse voltage and pulse duration, gas type and gas mixture, gas flow rates and the implantation dose are studied. The ion dose is calculated by dynamic sheath model and the plasma parameters are calculated from the V-I characteristic and power balance equation by homogeneous model of rf plasma discharge considering Ohmic as well as Stochastic heating. The correlations between the yield of the implantation process and the physical parameters as well as plasma parameters are discussed. (author)

  14. Multi-instrument observations of nightside plasma patches under conditions of IMF Bz positive

    Directory of Open Access Journals (Sweden)

    V. S. C. Howells

    2008-08-01

    Full Text Available Results are presented from two multi-instrument case studies showing patches of cold, long-lived plasma in the winter nightside ionosphere during times when the z-component of the Interplanetary Magnetic Field (IMF Bz was positive. These enhancements were coincident with the antisunward convective plasma drift, flowing from polar to nightside auroral latitudes. In the first case, on 5 December 2005 with IMF By negative, two regions of enhanced electron density were observed extended in MLT in the magnetic midnight sector separated by lower densities near midnight. It is likely that the earlier enhancement originated on the dayside near magnetic noon and was transported to the nightside sector in the convective flow, whilst the later feature originated in the morning magnetic sector. The lower densities separating the two enhancements were a consequence of a pair of lobe cells essentially blocking the direct antisunward cross polar flow from the dayside. A second case study on 4 February 2006 with IMF By positive revealed a single nightside enhancement likely to have originated in the morning magnetic sector. These multi-instrument investigations, incorporating observations by the EISCAT radar facility, the SuperDARN network and radio tomography, reveal that plasma flowing from the dayside can play a significant role in the nightside ionosphere under conditions of IMF Bz positive. The observations are reinforced by simulations of flux-tube transport and plasma decay.

  15. Observation of ion acoustic multi-Peregrine solitons in multicomponent plasma with negative ions

    Science.gov (United States)

    Pathak, Pallabi; Sharma, Sumita K.; Nakamura, Y.; Bailung, H.

    2017-12-01

    The evolution of the multi-Peregrine soliton is investigated in a multicomponent plasma and found to be critically dependent on the initial bound state. Formation and splitting of Peregrine soliton, broadening of the frequency spectra provide clear evidence of nonlinear-dispersive focusing due to modulational instability, a generic mechanism for rogue wave formation in which amplitude and phase modulation grow as a result of interplay between nonlinearity and anomalous dispersion. We have shown that initial perturbation parameters (amplitude & temporal length) critically determine the number of solitons evolution. It is also found that a sufficiently long wavelength perturbation of high amplitude invoke strong nonlinearity to generate a supercontinuum state. Continuous Wavelet Transform (CWT) and Fast Fourier Transform (FFT) analysis of the experimental time series data clearly indicate the spatio-temporal localization and spectral broadening. We consider a model based on the frame work of Nonlinear Schrodinger equation (NLSE) to explain the experimental observations.

  16. Identification and observations of the plasma mantle at low altitude

    International Nuclear Information System (INIS)

    Newell, P.T.; Meng, Ching-I.; Sanchez, E.R.; Burke, W.J.; Greenspan, M.E.

    1991-01-01

    The direct injection of magnetosheath plasma into the cusp produces at low altitude a precipitation regime with an energy-latitude dispersion-the more poleward portion of which the authors herein term the cusp plume. An extensive survey of the Defense Meteorological Satellite Program (DMSP) F7 and F9 32 eV to 30 keV precipitating particle data shows that similar dispersive signatures exist over much of the dayside, just poleward of the auroral oval. Away from noon (or more precisely, anywhere not immediately poleward of the cusp) the fluxes are reduced by a factor of about 10 as compared to the cusp plume, but other characteristics are quite similar. For example, the inferred temperatures and flow velocities, and the characteristic decline of energy and number flux with increasing latitude is essentially the same in a longitudinally broad ring of precipitation a few degrees thick in latitude over much of the dayside. They conclude that the field lines on which such precipitation occurs thread the magnetospheric plasma mantle over the entire longitudinally extended ring. Besides the location of occurence (i.e., immediately poleward of the dayside oval), the identification is based especially on the associated very soft ion spectra, which have densities from a few times 10 -2 to a few times 10 -1 /cm 3 ; on the temperature range, which is form from a few tens of eV up to about 200 eV; amd on the characteristic gradients with latitude. Further corroborating evidence that the precipitation is associated with field lines which thread the plasma mantle includes drift meter observations which show that regions so identified based on the particle data consistently lie on antisunward convecting field lines. The observations indicate that some dayside high-latitude auroral features just poleward of the auroral oval are embedded in the plasma mantle

  17. The study of a plasma jet injected by an on-board plasma thruster

    International Nuclear Information System (INIS)

    Grebnev, I.A.; Ivanov, G.V.; Khodnenko, V.P.

    1981-01-01

    The injection of a steady plasma jet into the ionosphere results in interactions which were studied in experiments conducted onboard two Meteor satellites in 1977-1979. The jet parameters at the propulsion system output were as follows: propulsive mass: Xe Xe (+) ion density at the nozzle section 3 x 10 to the 11th per cu cm plasma stream divergence: 20 degrees jet velocity: 10-12 km/cm ion energy: 130 eV electron temperature: 1 + 3 eV. A Bennett-type modified radio-frequency mass-spectrometer and a two-channel electromagnetic wave analyzer were used for the measurements. It was found that (1) the injected plasma jet propagation depends on the jet injection pitch angle (2) when the plasma jet was injected along the magnetic field, impactless jet spreading took place without considerable interaction with the ionospheric plasma (3) when the plasma jet was injected across the magnetic field, considerable interaction was observed between the plasma jet/ionospheric plasma and the earth's magnetic field and (4) electromagnetic fields were generated near the satellite by plasma jet interaction

  18. ECR Plasma Photos

    International Nuclear Information System (INIS)

    Racz, R.; Biri, S.; Palinkas, J.

    2009-01-01

    Complete text of publication follows. In order to observe and study systematically the plasma of electron cyclotron resonance (ECR) ion sources (ECRIS) we made a high number of high-resolution visible light plasma photos and movies in the ATOMKI ECRIS Laboratory. This required building the ECR ion source into an open plasma device, temporarily. An 8MP digital camera was used to record photos of plasmas made from He, methane, N, O, Ne, Ar, Kr, Xe gases and from their mixtures. The effects of the main external setting parameters (gas pressure, gas composition, magnetic field, microwave power, microwave frequency) were studied to the shape, color and structure of the plasma. The double frequency mode (9+14 GHz) was also realized and photos of this special 'star-in-star' shape plasma were recorded. A study was performed to analyze and understand the color of the ECR plasmas. The analysis of the photo series gave us many qualitative and numerous valuable physical information on the nature of ECR plasmas. To our best knowledge our work is the first systematic study of ECR plasmas in the visible light region. When looking in the plasma chamber of an ECRIS we can see an axial image of the plasma (figure 1) in conformity with experimental setup. Most of the quantitative information was obtained through the summarised values of the Analogue Digital Unit (ADU) of pixels. By decreasing the strength of the magnetic trap we clearly observed that the brightness of the central part of the plasma gradually decreases, i.e. the plasma becomes more and more 'empty'. Figure 2 shows a photo series of ECR plasma at decreasing axial magnetic field. The radial size of the plasma increased because of the ascendant resonant zone. By increasing the power of the injected microwave an optimum (or at least saturation) was found in the brightness of the plasma. We found correlation between the gas dosing rates and plasma intensities. When sweeping the frequency of the microwave in a wide region

  19. Observation of intense beam in low pressure from IPR Plasma Focus facility

    International Nuclear Information System (INIS)

    Kumar, R.; Shyam, A.; Chaturvedi, S.; Lathi, D.; Sarkar, Partha; Chaudhari, V.; Verma, R.; Shukla, R.; Debnath, K.; Sonara, J.; Shah, K.; Adhikary, B.

    2004-01-01

    Full text: Plasma focus (PF) is a powerful source of various ionizing radiation such as charged particles beam (ions and electrons), X-ray, neutrons etc. This device can operate from energy level of 50J to 1MJ. Plasma Focus is relatively small, simple and cheap in comparison with other radiation sources based on isotopes, accelerators and fusion reactors. Radiation pulse from PF is strong and very short. Now with the new pulsed power technology this device can be operated repeatedly with enhanced lifetime. All these features make plasma focus a versatile device for academic as well as industrial interest such as hot plasma physics and plasma collective processes, equation of state of matter under extreme conditions, material science including material characterization, dynamic equation control, and surface modification and destruction test. Intense burst of neutrons have been observed from a low energy (3.6 kJ) Mather type plasma focus device operated in 0.4 Torr pressure of deuterium medium at IPR. The emitted neutrons (10 9 /shot), that are accompanied by a strong hard X-ray pulse, were found to be having energy up to 3.26 MeV in the axial direction of the device

  20. Impact of gas puffing location on density control and plasma parameters in TJ-II

    International Nuclear Information System (INIS)

    Tabares, F.L.; Garcia-Cortes, I.; Estrada, T.; Tafalla, D.; Hidalgo, A.; Ferreira, J.A.; Pastor, I.; Herranz, J.; Ascasibar, E.

    2005-01-01

    Under pure Electron Cyclotron Resonance Heating (ECRH) conditions in TJ-II plasmas (P<300 kW, 53.2 GHz, 2nd harmonic X-mode, power density < 25 W/m''3), plasma start-up and good density control are obtained only by the proper combination of wall conditions and gas puffing characteristics. Such a control is particularly critical for the optimisation of the NBI power transfer to the target plasmas. The relatively low cut-off limit is easily reached due not only to the unfavourable wall/puffing-fuelling ratio but also due to the steep density profiles developed during the Enhanced Particle Confinement (EPC) modes. These modes are triggered by the gas puffing waveform, and they cannot be achieved for high iota magnetic configurations in TJ-II. Comparative experiments under metallic and boronised wall conditions have shown that the sensitivity of the EPC modes to the puffing rate is at least partially related to the energy balance at the plasma periphery under central heating scenarios. In this work, the impact of gas-fuelling location on the plasma parameters and density control is described. For that purpose, three different fuelling locations have been investigated; broad distribution from a side ports, localized injection from long tubes at different poloidal positions and highly localized injection through a movable limiter. Edge density and temperature profiles from a broad set of diagnostics (atomic beams, reflectometry, Thompson Scattering ECE, etc...) are analysed and compared. It has been found that preventing from transition to the EPC mode is achieved by using slow puffing rates, while neutral penetration into the plasma core can be enhanced for highly localized gas sources. Wall inventory, however, has been found to pl ay a dominant role in the fuelling of the plasma under most conditions. (author)

  1. The Inner Magnetosphere Plasma Response to Interplanetary Shocks: Van Allen Probes HOPE Observations

    Science.gov (United States)

    Winter, L. M.; Denton, M.; Ferradas, C.; Henderson, M. G.; Larsen, B.; Reeves, G.; Skoug, R. M.; Thomsen, M. F.

    2017-12-01

    The Van Allen Probes' Helium, Oxygen, Proton, and Electron (HOPE) sensors measure ion and electron populations in the plasmasphere, plasma sheet, and lower-energy ring current, providing unique observations at low energies (0.001-50 keV) and low L-shell (down to 1.5 RE). We use the capabilities of these two spacecraft to probe changes in the low energy particles in response to interplanetary (IP) shocks. We focus on changes in the plasma energies, composition, and pitch angle distributions following IP shocks and storm sudden commencements from 2012-2017 through a comparison of HOPE observations preceding and post shock.

  2. Visualizing the influence of the process parameters on the keyhole dimensions in plasma arc welding

    International Nuclear Information System (INIS)

    Liu, Z M; Wu, C S; Chen, M A

    2012-01-01

    The keyhole status and its dimensions are critical information determining both the process quality and weld quality in plasma arc welding (PAW). It is of great significance to measure the keyhole shape and size and to correlate them with the main process parameters. In this study, a low-cost vision system is developed to visualize the keyhole at the backside of the test-pieces in PAW. Three stages of keyhole evolution, i.e. initial blind stage (non-penetrated keyhole), unstable stage with momentarily disappeared keyhole and quasi-steady open keyhole stage (fully-penetrated keyhole), are measured in real-time during the PAW tests on stainless steel test-pieces of thickness 8 mm. Based on the captured images of keyhole under different welding conditions, the correlations of the main welding process parameters (welding current, welding speed, plasma gas flow rate) with the keyhole length, width and area are visualized through vision measurement. It lays a solid foundation for implementing keyhole stability control and process optimization in keyhole PAW. (paper)

  3. A contoured gap coaxial plasma gun with injected plasma armature.

    Science.gov (United States)

    Witherspoon, F Douglas; Case, Andrew; Messer, Sarah J; Bomgardner, Richard; Phillips, Michael W; Brockington, Samuel; Elton, Raymond

    2009-08-01

    A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 microg of plasma with density above 10(17) cm(-3) to greater than 200 km/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, high energy density plasmas, and others. The approach uses symmetric injection of high density plasma into a coaxial electromagnetic accelerator having an annular gap geometry tailored to prevent formation of the blow-by instability. The injected plasma is generated by numerous (currently 32) radially oriented capillary discharges arranged uniformly around the circumference of the angled annular injection region of the accelerator. Magnetohydrodynamic modeling identified electrode profiles that can achieve the desired plasma jet parameters. The experimental hardware is described along with initial experimental results in which approximately 200 microg has been accelerated to 100 km/s in a half-scale prototype gun. Initial observations of 64 merging injector jets in a planar cylindrical testing array are presented. Density and velocity are presently limited by available peak current and injection sources. Steps to increase both the drive current and the injected plasma mass are described for next generation experiments.

  4. A contoured gap coaxial plasma gun with injected plasma armature

    International Nuclear Information System (INIS)

    Witherspoon, F. Douglas; Case, Andrew; Messer, Sarah J.; Bomgardner, Richard II; Phillips, Michael W.; Brockington, Samuel; Elton, Raymond

    2009-01-01

    A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 μg of plasma with density above 10 17 cm -3 to greater than 200 km/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, high energy density plasmas, and others. The approach uses symmetric injection of high density plasma into a coaxial electromagnetic accelerator having an annular gap geometry tailored to prevent formation of the blow-by instability. The injected plasma is generated by numerous (currently 32) radially oriented capillary discharges arranged uniformly around the circumference of the angled annular injection region of the accelerator. Magnetohydrodynamic modeling identified electrode profiles that can achieve the desired plasma jet parameters. The experimental hardware is described along with initial experimental results in which approximately 200 μg has been accelerated to 100 km/s in a half-scale prototype gun. Initial observations of 64 merging injector jets in a planar cylindrical testing array are presented. Density and velocity are presently limited by available peak current and injection sources. Steps to increase both the drive current and the injected plasma mass are described for next generation experiments.

  5. Observations of acoustic-wave-induced superluminescence in an argon plasma

    International Nuclear Information System (INIS)

    Aramyan, A.R.

    2003-01-01

    It is shown that in an argon discharge plasma it is possible to obtain overpopulation of certain electronic levels of atomic argon under the influence of acoustic waves. When the specified threshold is exceeded, then a superluminescence (in the form of light flashes) from the overpopulated electronic levels of atomic argon is observed

  6. Sub-kilometer Simulation of Equatorial Plasma Bubble and Comparison with Satellite Observations

    Science.gov (United States)

    Yokoyama, T.; Pfaff, R. F., Jr.; Stolle, C.; Su, S. Y.

    2016-12-01

    Equatorial plasma bubble (EPB) is a well-known phenomenon in the equatorial ionospheric F region. As it causes severe scintillation in the amplitude and phase of radio signals, it is important to understand and forecast the occurrence of EPB from a space weather point of view. The development of EPB is presently believed as an evolution of the generalized Rayleigh-Taylor instability. We have already developed a 3D high-resolution bubble (HIRB) model with a grid spacing of as small as 1 km and presented nonlinear growth of EPB which shows very turbulent internal structures such as bifurcation and pinching. Recent upgrade of the HIRB model has made it possible to conduct the simulation with sub-kilometer grid spacing. The simulation results can be compared with various in situ satellite observations such as plasma drift velocity, plasma density, magnetic field, and their structures and power spectra, e.g. from the C/NOFS, ROCSAT, CHAMP, or Swarm missions. Our initial results show encouraging agreement between model results and observational data.

  7. Observation of Electron Energy Pinch in HT-7 ICRF Heated Plasmas

    International Nuclear Information System (INIS)

    Ding Siye; Wan Baonian; Ti Ang; Zhang Xinjun; Liu Zixi; Qian Jinping; Zhong Guoqiang; Duan Yanmin; Wang Lu

    2014-01-01

    Inward energy transport (pinch phenomenon) in the electron channel is observed in HT-7 plasmas using off-axis ion cyclotron resonance frequency (ICRF) heating. Experimental results and power balance transport analysis by TRANSP code are presented in this article. With the aids of GLF23 and Chang-Hinton transport models, which predict energy diffusivity in experimental conditions, the estimated electron pinch velocity is obtained by experimental data and is found reasonably comparable to the results in the previous study, such as Song on Tore Supra. Density scanning shows that the energy convective velocity in the electron channel has a close relation to density scale length, which is qualitatively in agreement with Wang's theoretical prediction. The parametric dependence of electron energy convective velocity on plasma current is still ambiguous and is worthy of future research on EAST. (magnetically confined plasma)

  8. Experimental studies of collisional plasma shocks and plasma interpenetration via merging supersonic plasma jets

    Science.gov (United States)

    Hsu, S. C.; Moser, A. L.; Merritt, E. C.; Adams, C. S.

    2015-11-01

    Over the past 4 years on the Plasma Liner Experiment (PLX) at LANL, we have studied obliquely and head-on-merging supersonic plasma jets of an argon/impurity or hydrogen/impurity mixture. The jets are formed/launched by pulsed-power-driven railguns. In successive experimental campaigns, we characterized the (a) evolution of plasma parameters of a single plasma jet as it propagated up to ~ 1 m away from the railgun nozzle, (b) density profiles and 2D morphology of the stagnation layer and oblique shocks that formed between obliquely merging jets, and (c) collisionless interpenetration transitioning to collisional stagnation between head-on-merging jets. Key plasma diagnostics included a fast-framing CCD camera, an 8-chord visible interferometer, a survey spectrometer, and a photodiode array. This talk summarizes the primary results mentioned above, and highlights analyses of inferred post-shock temperatures based on observations of density gradients that we attribute to shock-layer thickness. We also briefly describe more recent PLX experiments on Rayleigh-Taylor-instability evolution with magnetic and viscous effects, and potential future collisionless shock experiments enabled by low-impurity, higher-velocity plasma jets formed by contoured-gap coaxial guns. Supported by DOE Fusion Energy Sciences and LANL LDRD.

  9. Centrifugal Separation and Equilibration Dynamics in an Electron-Antiproton Plasma

    International Nuclear Information System (INIS)

    Andresen, G. B.; Bowe, P. D.; Hangst, J. S.; Ashkezari, M. D.; Hayden, M. E.; Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C.; Bertsche, W.; Butler, E.; Charlton, M.; Deller, A.; Eriksson, S.; Humphries, A. J.; Madsen, N.; Werf, D. P. van der; Cesar, C. L.; Friesen, T.

    2011-01-01

    Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments.

  10. Centrifugal separation and equilibration dynamics in an electron-antiproton plasma

    CERN Document Server

    Andresen, G B; Baquero-Ruiz, Marcelo; Bertsche, William; Bowe, Paul D; Butler, Eoin; Cesar, Claudio L; Chapman, Steven; Charlton, Michael; Deller, A; Eriksson, S; Fajans, Joel; Friesen, Tim; Fujiwara, Makoto C; Gill, David R; Gutierrez, A; Hangst, Jeffrey S; Hardy, Walter N; Hayden, Michael E; Humphries, Andrew J; Hydomako, Richard; Jonsell, Svante; Madsen, Niels; Menary, Scott; Nolan, Paul; Olin, Art; Povilus, Alexander; Pusa, Petteri; Robicheaux, Francis; Sarid, Eli; Silveira, Daniel M; So, Chukman; Storey, James W; Thompson, Robert I; van der Werf, Dirk P; Wurtele, Jonathan S; Yamazaki, Yasunori

    2011-01-01

    Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally-separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally-separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments.

  11. Propagation of high frequency electrostatic surface waves along the planar interface between plasma and dusty plasma

    Science.gov (United States)

    Mishra, Rinku; Dey, M.

    2018-04-01

    An analytical model is developed that explains the propagation of a high frequency electrostatic surface wave along the interface of a plasma system where semi-infinite electron-ion plasma is interfaced with semi-infinite dusty plasma. The model emphasizes that the source of such high frequency waves is inherent in the presence of ion acoustic and dust ion acoustic/dust acoustic volume waves in electron-ion plasma and dusty plasma region. Wave dispersion relation is obtained for two distinct cases and the role of plasma parameters on wave dispersion is analyzed in short and long wavelength limits. The normalized surface wave frequency is seen to grow linearly for lower wave number but becomes constant for higher wave numbers in both the cases. It is observed that the normalized frequency depends on ion plasma frequencies when dust oscillation frequency is neglected.

  12. Observational constraint on spherical inhomogeneity with CMB and local Hubble parameter

    Science.gov (United States)

    Tokutake, Masato; Ichiki, Kiyotomo; Yoo, Chul-Moon

    2018-03-01

    We derive an observational constraint on a spherical inhomogeneity of the void centered at our position from the angular power spectrum of the cosmic microwave background (CMB) and local measurements of the Hubble parameter. The late time behaviour of the void is assumed to be well described by the so-called Λ-Lemaȋtre-Tolman-Bondi (ΛLTB) solution. Then, we restrict the models to the asymptotically homogeneous models each of which is approximated by a flat Friedmann-Lemaȋtre-Robertson-Walker model. The late time ΛLTB models are parametrized by four parameters including the value of the cosmological constant and the local Hubble parameter. The other two parameters are used to parametrize the observed distance-redshift relation. Then, the ΛLTB models are constructed so that they are compatible with the given distance-redshift relation. Including conventional parameters for the CMB analysis, we characterize our models by seven parameters in total. The local Hubble measurements are reflected in the prior distribution of the local Hubble parameter. As a result of a Markov-Chains-Monte-Carlo analysis for the CMB temperature and polarization anisotropies, we found that the inhomogeneous universe models with vanishing cosmological constant are ruled out as is expected. However, a significant under-density around us is still compatible with the angular power spectrum of CMB and the local Hubble parameter.

  13. The impact of BMI on sperm parameters and the metabolite changes of seminal plasma concomitantly.

    Science.gov (United States)

    Guo, Dan; Wu, Wei; Tang, Qiuqin; Qiao, Shanlei; Chen, Yiqiu; Chen, Minjian; Teng, Mengying; Lu, Chuncheng; Ding, Hongjuan; Xia, Yankai; Hu, Lingqing; Chen, Daozhen; Sha, Jiahao; Wang, Xinru

    2017-07-25

    The development of male infertility increased rapidly worldwide, which coinciding with the epidemic of obesity. However, the impact of weight abnormalities on sperm quality is still contestable. To assess the correlation between BMI and sperm parameters, we searched relevant articles in PubMed, Embase, Web of science, and Wanfang database published until June 2015 without language restriction. Otherwise, we also recruited some participants who attended fertility clinic as well as some general populations in this report. We performed a systematic review and meta-analysis about BMI and sperm parameters containing total sperm count, concentration, semen volume and sperm motility (overall and progressive). Metabolomic analysis of seminal plasma was performed to explore the mechanism from a new perspective. This study found standardized weighted mean differences (SMD) in sperm parameters (total sperm count, sperm concentration, and semen volume) of abnormal weight groups decreased to different degree compared to normal weight. Dose-response analysis found SMD of sperm count, sperm concentration and semen volume respectively fell 2.4%, 1.3% and 2.0% compared with normal weight for every 5-unit increase in BMI. Metabolomic analysis of seminal plasma showed that spermidine and spermine were likely to play a vital role in the spermatogenesis progress. This systematic review with meta-analysis has confirmed there was a relationship between BMI and sperm quality, suggesting obesity may be a detrimental factor of male infertility.

  14. Influence of plasma parameters in pulsed plasma gun on modification processes in exposed structural materials

    International Nuclear Information System (INIS)

    Byrka, O.V.; Bandura, A.N.; Chebotarev, V.V.; Garkusha, I.E.; Garkusha, V.V.; Makhai, V.A.; Tereshin, V.I.

    2011-01-01

    This paper is focused on investigation of helium, nitrogen and krypton plasma streams generated by pulsed plasma gun (PPA). The main objection of this study is adjustment of plasma treatment regimes for different materials that allows achieving optimal thickness of modified layer with simultaneously minimal value of surface roughness. Features of materials alloying from gas and metallic plasma as a result of the plasma ions mixing with the steel substrate in liquid phase are discussed also.

  15. Analytical investigation on domain of decentered parameter for self-focusing of Hermite-cosh-Gaussian laser beam in collisional plasma

    Science.gov (United States)

    Valkunde, Amol T.; Patil, Sandip D.; Vhanmore, Bandopant D.; Urunkar, Trupti U.; Gavade, Kusum M.; Takale, Mansing V.; Fulari, Vijay J.

    2018-03-01

    In the present paper, an analytically investigated domain of decentered parameter and its effect on the self-focusing of Hermit-cosh-Gaussian (HChG) laser beams in a collisional plasma have been studied theoretically. The nonlinearity in the dielectric constant of plasma arising due to the nonuniform heating of carriers along the wavefront of the laser beam has been employed in the present investigation. The nonlinear differential equation of beam width parameter for various laser modes of HChG beam is obtained by following the standard Akhamanov's parabolic equation approach under Wentzel-Kramers-Brillouin and paraxial approximations. The analytical treatment has enabled us to define three distinct regions: self-focusing, self-trapping and defocusing, which are presented graphically.

  16. Hypervelocity dust particle impacts observed by the Giotto Magnetometer and Plasma Experiments

    OpenAIRE

    Neubauer, F. M.; Glassmeier, K. H.; Coates, A. J.; Goldstein, R.; Acuña, M. H.; Musmann, G.

    1990-01-01

    We report thirteen very short events in the magnetic field of the inner magnetic pile‐up region of comet Halley observed by the Giotto magnetometer experiment together with simultaneous plasma data obtained by the Johnstone plasma analyzer and the ion mass spectrometer experiments. The events are due to dust impacts in the milligram range on the spacecraft at the relative velocity between the cemetery dust and the spacecraft of 68 km/sec. They are generally consistent with dust impact events ...

  17. MMS Observations of Ion-Scale Magnetic Island in the Magnetosheath Turbulent Plasma

    Science.gov (United States)

    Huang, S. Y.; Sahraoui, F.; Retino, A.; Contel, O. Le; Yuan, Z. G.; Chasapis, A.; Aunai, N.; Breuillard, H.; Deng, X. H.; Zhou, M.; hide

    2016-01-01

    In this letter, first observations of ion-scale magnetic island from the Magnetospheric Multiscale mission in the magnetosheath turbulent plasma are presented. The magnetic island is characterized by bipolar variation of magnetic fields with magnetic field compression, strong core field, density depletion, and strong currents dominated by the parallel component to the local magnetic field. The estimated size of magnetic island is about 8 di, where di is the ion inertial length. Distinct particle behaviors and wave activities inside and at the edges of the magnetic island are observed: parallel electron beam accompanied with electrostatic solitary waves and strong electromagnetic lower hybrid drift waves inside the magnetic island and bidirectional electron beams, whistler waves, weak electromagnetic lower hybrid drift waves, and strong broadband electrostatic noise at the edges of the magnetic island. Our observations demonstrate that highly dynamical, strong wave activities and electron-scale physics occur within ion-scale magnetic islands in the magnetosheath turbulent plasma..

  18. Plasma barodiffusion in inertial-confinement-fusion implosions: application to observed yield anomalies in thermonuclear fuel mixtures.

    Science.gov (United States)

    Amendt, Peter; Landen, O L; Robey, H F; Li, C K; Petrasso, R D

    2010-09-10

    The observation of large, self-generated electric fields (≥10(9)  V/m) in imploding capsules using proton radiography has been reported [C. K. Li, Phys. Rev. Lett. 100, 225001 (2008)]. A model of pressure gradient-driven diffusion in a plasma with self-generated electric fields is developed and applied to reported neutron yield deficits for equimolar D3He [J. R. Rygg, Phys. Plasmas 13, 052702 (2006)] and (DT)3He [H. W. Herrmann, Phys. Plasmas 16, 056312 (2009)] fuel mixtures and Ar-doped deuterium fuels [J. D. Lindl, Phys. Plasmas 11, 339 (2004)]. The observed anomalies are explained as a mild loss of deuterium nuclei near capsule center arising from shock-driven diffusion in the high-field limit.

  19. Direct observations of blob deformation during a substorm

    Directory of Open Access Journals (Sweden)

    T. Ishida

    2015-05-01

    Full Text Available Ionospheric blobs are localized plasma density enhancements, which are mainly produced by the transportation process of plasma. To understand the deformation process of a blob, observations of plasma parameters with good spatial–temporal resolution are desirable. Thus, we conducted the European Incoherent Scatter radar observations with high-speed meridional scans (60–80 s during October and December 2013, and observed the temporal evolution of a blob during a substorm on 4 December 2013. This paper is the first report of direct observations of blob deformation during a substorm. The blob deformation arose from an enhanced plasma flow shear during the substorm expansion phase, and then the blob split into two smaller-scale blobs, whose scale sizes were more than ~100 km in latitude. Our analysis indicates that the Kelvin–Helmholtz instability and dissociative recombination could have deformed the blob structure.

  20. Observations of suppressed retention and blistering for tungsten exposed to deuterium-helium mixture plasmas

    International Nuclear Information System (INIS)

    Miyamoto, M.; Morito, S.; Ono, K.; Nishijima, D.; Doerner, R.P.; Baldwin, M.J.; Hanna, J.; Ueda, Y.; Kurishita, H.

    2009-01-01

    Blister formation and D retention in W have been investigated for low energy (∼55 ± 15 eV), high flux (∼10 22 m -2 s -1 ), high fluence (≤4.5 x 10 26 m -2 ) ion bombardment at moderate temperature (∼573 K) in mixed species D+He plasmas in the linear divertor plasma simulator PISCES-A. The amount of D retained in W is found to decrease significantly when compared with that in W exposed to pure D plasmas, as measured with high resolution thermal desorption spectroscopy. Scanning electron microscopy observations reveal the suppression of the blisters, a surface feature known to drive up retention, in the D + He mixture plasma exposed W samples. Reduced D retention is accompanied by the formation of nano-sized high density He bubbles in the near surface, observed with a transmission electron microscope (TEM). It is believed that the nano-bubbles act as a diffusion barrier to implanted D atoms and consequently reduce the amount of uptake in the W material. This newly observed effect implies that current predictions of D retention in W, in actual fusion devices, may be overestimated, since there will be He ash in fusion plasma. Toughness enhanced, fine-grained (grain size of ∼1 μm) W-TiC samples, exposed to pure D plasma conditions, also show little or no evidence of blistering. The measured D retention in the W-TiC samples was approximately 1 x 10 19 D m -2 corresponding to about 2 x 10 -7 of the implanted D fluence, and is very low compared with the retention in pure stress relieved W, which exhibited surface blisters and had a D retention of about 1 x 10 21 D m -2 .

  1. Strong self-focusing of a cosh-Gaussian laser beam in collisionless magneto-plasma under plasma density ramp

    International Nuclear Information System (INIS)

    Nanda, Vikas; Kant, Niti

    2014-01-01

    The effect of plasma density ramp on self-focusing of cosh-Gaussian laser beam considering ponderomotive nonlinearity is analyzed using WKB and paraxial approximation. It is noticed that cosh-Gaussian laser beam focused earlier than Gaussian beam. The focusing and de-focusing nature of the cosh-Gaussian laser beam with decentered parameter, intensity parameter, magnetic field, and relative density parameter has been studied and strong self-focusing is reported. It is investigated that decentered parameter “b” plays a significant role for the self-focusing of the laser beam as for b=2.12, strong self-focusing is seen. Further, it is observed that extraordinary mode is more prominent toward self-focusing rather than ordinary mode of propagation. For b=2.12, with the increase in the value of magnetic field self-focusing effect, in case of extraordinary mode, becomes very strong under plasma density ramp. Present study may be very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, and x-ray lasers. Moreover, plasma density ramp plays a vital role to enhance the self-focusing effect

  2. Strong self-focusing of a cosh-Gaussian laser beam in collisionless magneto-plasma under plasma density ramp

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, Vikas; Kant, Niti, E-mail: nitikant@yahoo.com [Department of Physics, Lovely Professional University, G. T. Road, Phagwara, Punjab 144411 (India)

    2014-07-15

    The effect of plasma density ramp on self-focusing of cosh-Gaussian laser beam considering ponderomotive nonlinearity is analyzed using WKB and paraxial approximation. It is noticed that cosh-Gaussian laser beam focused earlier than Gaussian beam. The focusing and de-focusing nature of the cosh-Gaussian laser beam with decentered parameter, intensity parameter, magnetic field, and relative density parameter has been studied and strong self-focusing is reported. It is investigated that decentered parameter “b” plays a significant role for the self-focusing of the laser beam as for b=2.12, strong self-focusing is seen. Further, it is observed that extraordinary mode is more prominent toward self-focusing rather than ordinary mode of propagation. For b=2.12, with the increase in the value of magnetic field self-focusing effect, in case of extraordinary mode, becomes very strong under plasma density ramp. Present study may be very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, and x-ray lasers. Moreover, plasma density ramp plays a vital role to enhance the self-focusing effect.

  3. Plasma parameters in the COMPASS divertor during Ohmic plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrova, M. [Institute of Plasma Physics, Academy of Sciences of the Czech Republic v.v.i., Prague (Czech Republic); Emil Djakov Institute of Electronics, Bulgarian Academy of Sciences, Sofia (Bulgaria); Dejarnac, R.; Stoeckel, J.; Havlicek, J.; Janky, F.; Panek, R. [Institute of Plasma Physics, Academy of Sciences of the Czech Republic v.v.i., Prague (Czech Republic); Popov, Ts.K. [Faculty of Physics, St. Kl. Ohridski University of Sofia (Bulgaria); Ivanova, P.; Vasileva, E. [Emil Djakov Institute of Electronics, Bulgarian Academy of Sciences, Sofia (Bulgaria); Kovacic, J. [Jozef Stefan Institute, Ljubljana (Slovenia)

    2014-04-15

    This paper reports on probe measurements of the electron energy distribution function and plasma potential in the divertor region of the COMPASS tokamak during D-shaped plasmas. The probe data have been processed using the novel first-derivative technique. A comparison with the results obtained by processing the same data with the classical probe technique, which assumes Maxwellian electron energy distribution functions is presented and discussed. In the vicinity of the inner and outer strike points of the divertor the electron energy distribution function can be approximated by a bi-Maxwellian, with a dominating low-energy electron population (4-7 eV) and a minority of higher energy electrons (12-25 eV). In the private flux region between the two strike points the electron energy distribution function is found to be Maxwellian with temperatures in the range of 7-10 eV. The comparative analysis using both techniques has allowed a better insight into the underlying physical processes at the divertor region of the COMPASS tokamak. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with neon

    Science.gov (United States)

    Malinina, A. A.; Malinin, A. N.

    2013-12-01

    Results are presented from studies of the optical characteristics and parameters of plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with neon—the working medium of a non-coaxial exciplex gas-discharge emitter. The electron energy distribution function, the transport characteristics, the specific power losses for electron processes, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering by the working mixture components are determined as functions of the reduced electric field. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules is found to be 1.6 × 10-14 m3/s for a reduced electric field of E/ N = 15 Td, at which the maximum emission intensity in the blue-green spectral region (λmax = 502 nm) was observed in this experiment.

  5. Effect of Mucuna pruriens on semen profile and biochemical parameters in seminal plasma of infertile men.

    Science.gov (United States)

    Ahmad, Mohammad Kaleem; Mahdi, Abbas Ali; Shukla, Kamla Kant; Islam, Najmul; Jaiswar, Shyam Pyari; Ahmad, Sohail

    2008-09-01

    To investigate the impact of Mucuna pruriens seeds on semen profiles and biochemical levels in seminal plasma of infertile men. Prospective study. Departments of Biochemistry and Obstetrics and Gynecology, King George's Medical University, Lucknow, India. Sixty normal healthy fertile men (controls) and 60 men undergoing infertility screening. High-performance liquid chromatography assay procedure for quantitation of vitamin A and E in seminal plasma. Biochemical parameters in seminal plasma, namely lipids, fructose, and vitamin C, were estimated by standard spectrophotometric procedures. Before and after the treatment, seminal plasma lipid profile, lipid peroxide, fructose, and antioxidant vitamin levels were measured. Treatment with M. pruriens significantly inhibited lipid peroxidation, elevated spermatogenesis, and improved sperm motility. Treatment also recovered the levels of total lipids, triglycerides, cholesterol, phospholipids, and vitamin A, C, and E and corrected fructose in seminal plasma of infertile men. Treatment with M. pruriens increased sperm concentration and motility in all the infertile study groups. Oligozoospermic patients recovered sperm concentration significantly, but sperm motility was not restored to normal levels in asthenozoospermic men. Furthermore, in the seminal plasma of all the infertile groups, the levels of lipids, antioxidant vitamins, and corrected fructose were recovered after a decrease in lipid peroxides after treatment. The present study is likely to open new vistas on the possible role of M. pruriens seed powder as a restorative and invigorating agent for infertile men.

  6. Determination of plasma Z-pinch effect by intrinsic stimulated emission

    International Nuclear Information System (INIS)

    Lue, J.T.; Liang, J.M.

    1977-01-01

    The plasma Z-pinch behavior has been observed in a relatively small-bore diameter tube and low bank voltage discharge system. The instant of the occurrence of the laser line at 4880 A coincides with the plasma pinch time calculated by using a one-fluid snow-plow model. A determination of plasma pinch parameters by measuring the intrinsic stimulated emission of the ions is described

  7. Magnetized whirls in plasma focus discharges

    International Nuclear Information System (INIS)

    Witalis, E.

    1979-05-01

    The plasma focus is briefly described with emphasis on its capabilities as a neutron source. The filamentary whirl structures observed in the discharge plasma are described. Starting with a simple, early and particularly well established case of vorticity imparted by a rotational electric field to the plasma in MHD generators, a general derivation is then outlined proving that such magnetically induced rotation is a general feature for the normally Hall-conducting magnetized plasma. Physical interpretations of the effect are given and objections to it are critically reviewed as is also a theory proposing radiation cooling as the cause of plasma filamentation. A more detailed derivation based essentially on the consistent description of the motion and the field generation of the charged plasma particles yields a theoretical model where the specific features of magnetically compressed plasmas are found. In particular, the ion collisionless skin depth is obtained as the key length parameter. This length is identified as roughly the whirl radius. In conjunction with a generalized Bennett relation theoretical whirl properties are predicted and found to agree with observations. Mechanisms that relate the whirls to nuclear fusion reaction conditions are tentatively indicated. (author)

  8. Probabilistic inference of ecohydrological parameters using observations from point to satellite scales

    Science.gov (United States)

    Bassiouni, Maoya; Higgins, Chad W.; Still, Christopher J.; Good, Stephen P.

    2018-06-01

    Vegetation controls on soil moisture dynamics are challenging to measure and translate into scale- and site-specific ecohydrological parameters for simple soil water balance models. We hypothesize that empirical probability density functions (pdfs) of relative soil moisture or soil saturation encode sufficient information to determine these ecohydrological parameters. Further, these parameters can be estimated through inverse modeling of the analytical equation for soil saturation pdfs, derived from the commonly used stochastic soil water balance framework. We developed a generalizable Bayesian inference framework to estimate ecohydrological parameters consistent with empirical soil saturation pdfs derived from observations at point, footprint, and satellite scales. We applied the inference method to four sites with different land cover and climate assuming (i) an annual rainfall pattern and (ii) a wet season rainfall pattern with a dry season of negligible rainfall. The Nash-Sutcliffe efficiencies of the analytical model's fit to soil observations ranged from 0.89 to 0.99. The coefficient of variation of posterior parameter distributions ranged from interest. In these cases, model inversion converged more slowly but ultimately provided better goodness of fit and lower uncertainty. Results were robust using as few as 100 daily observations randomly sampled from the full records, demonstrating the advantage of analyzing soil saturation pdfs instead of time series to estimate ecohydrological parameters from sparse records. Our work combines modeling and empirical approaches in ecohydrology and provides a simple framework to obtain scale- and site-specific analytical descriptions of soil moisture dynamics consistent with soil moisture observations.

  9. Influence of spray parameters on the microstructure and mechanical properties of gas-tunnel plasma sprayed hydroxyapatite coatings

    International Nuclear Information System (INIS)

    Morks, M.F.; Kobayashi, Akira

    2007-01-01

    For biomedical applications, hydroxyapatite (HA) coatings were deposited on 304 stainless steel substrate by using a gas tunnel type plasma spraying process. The influences of spraying distances and plasma arc currents on the microstructure, hardness and adhesion properties of HA coatings were investigated. Microstructure observation by SEM showed that HA coatings sprayed at low plasma power have a porous structure and poor hardness. HA coatings sprayed at high plasma power and short spraying distance are characterized by good adhesion and low porosity with dense structure. Hardness increased for HA coatings sprayed at shorter spraying distance and higher plasma power, mainly due to the formation of dense coatings

  10. A contoured gap coaxial plasma gun with injected plasma armature

    Energy Technology Data Exchange (ETDEWEB)

    Witherspoon, F. Douglas; Case, Andrew; Messer, Sarah J.; Bomgardner, Richard II; Phillips, Michael W.; Brockington, Samuel; Elton, Raymond [HyperV Technologies Corp., Chantilly, Virginia 20151 (United States)

    2009-08-15

    A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 {mu}g of plasma with density above 10{sup 17} cm{sup -3} to greater than 200 km/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, high energy density plasmas, and others. The approach uses symmetric injection of high density plasma into a coaxial electromagnetic accelerator having an annular gap geometry tailored to prevent formation of the blow-by instability. The injected plasma is generated by numerous (currently 32) radially oriented capillary discharges arranged uniformly around the circumference of the angled annular injection region of the accelerator. Magnetohydrodynamic modeling identified electrode profiles that can achieve the desired plasma jet parameters. The experimental hardware is described along with initial experimental results in which approximately 200 {mu}g has been accelerated to 100 km/s in a half-scale prototype gun. Initial observations of 64 merging injector jets in a planar cylindrical testing array are presented. Density and velocity are presently limited by available peak current and injection sources. Steps to increase both the drive current and the injected plasma mass are described for next generation experiments.

  11. Analysis of multidimensional difference-of-Gaussians filters in terms of directly observable parameters.

    Science.gov (United States)

    Cope, Davis; Blakeslee, Barbara; McCourt, Mark E

    2013-05-01

    The difference-of-Gaussians (DOG) filter is a widely used model for the receptive field of neurons in the retina and lateral geniculate nucleus (LGN) and is a potential model in general for responses modulated by an excitatory center with an inhibitory surrounding region. A DOG filter is defined by three standard parameters: the center and surround sigmas (which define the variance of the radially symmetric Gaussians) and the balance (which defines the linear combination of the two Gaussians). These parameters are not directly observable and are typically determined by nonlinear parameter estimation methods applied to the frequency response function. DOG filters show both low-pass (optimal response at zero frequency) and bandpass (optimal response at a nonzero frequency) behavior. This paper reformulates the DOG filter in terms of a directly observable parameter, the zero-crossing radius, and two new (but not directly observable) parameters. In the two-dimensional parameter space, the exact region corresponding to bandpass behavior is determined. A detailed description of the frequency response characteristics of the DOG filter is obtained. It is also found that the directly observable optimal frequency and optimal gain (the ratio of the response at optimal frequency to the response at zero frequency) provide an alternate coordinate system for the bandpass region. Altogether, the DOG filter and its three standard implicit parameters can be determined by three directly observable values. The two-dimensional bandpass region is a potential tool for the analysis of populations of DOG filters (for example, populations of neurons in the retina or LGN), because the clustering of points in this parameter space may indicate an underlying organizational principle. This paper concentrates on circular Gaussians, but the results generalize to multidimensional radially symmetric Gaussians and are given as an appendix.

  12. Experimental observation of current generation by asymmetrical heating of ions in a tokamak plasma

    International Nuclear Information System (INIS)

    Gahl, J.; Ishihara, O.; Wong, K.L.; Kristiansen, M.; Hagler, M.

    1986-01-01

    The first experimental observation of current generation by asymmetrical heating of ions is reported. Ions were asymmetrically heated by a unidirectional fast Alfven wave launched by a slow wave antenna inside a tokamak. Current generation was detected by measuring the asymmetry of the toroidal plasma current with probes at the top and bottom of the toroidal plasma column

  13. Observational constraints on Hubble parameter in viscous generalized Chaplygin gas

    Science.gov (United States)

    Thakur, P.

    2018-04-01

    Cosmological model with viscous generalized Chaplygin gas (in short, VGCG) is considered here to determine observational constraints on its equation of state parameters (in short, EoS) from background data. These data consists of H(z)-z (OHD) data, Baryonic Acoustic Oscillations peak parameter, CMB shift parameter and SN Ia data (Union 2.1). Best-fit values of the EoS parameters including present Hubble parameter (H0) and their acceptable range at different confidence limits are determined. In this model the permitted range for the present Hubble parameter and the transition redshift (zt) at 1σ confidence limits are H0= 70.24^{+0.34}_{-0.36} and zt=0.76^{+0.07}_{-0.07} respectively. These EoS parameters are then compared with those of other models. Present age of the Universe (t0) have also been determined here. Akaike information criterion and Bayesian information criterion for the model selection have been adopted for comparison with other models. It is noted that VGCG model satisfactorily accommodates the present accelerating phase of the Universe.

  14. Observation of magnetic field perturbations during sawtooth activity in tokamak plasmas

    International Nuclear Information System (INIS)

    Soltwisch, H.; Koslowski, H.R.

    1997-01-01

    Sawtooth activity is a prominent example of a global plasma instability which is observed in virtually all tokamak devices. Despite numerous experimental and theoretical investigations, the phenomenon is still barely understood. As far as experimental effort is concerned, much attention has been paid to soft X-ray emission from the plasma and to its analysis in terms of two-dimensional contour plots, because it is thought to reflect the shape and temporal behaviour of magnetic flux surfaces during a sawtooth cycle. Recently, more direct methods of detecting sawtooth-related changes in the magnetic field structure have become available and have added new facets to the general picture. In this picture, some observations made on the Juelich tokamak TEXTOR by means of a Faraday rotation diagnostic technique will be reported. First, in correlation with the sawtooth collapse a localized periodic perturbation of the magnetic field with principal mode numbers m = 1 and n = 0 has been detected which, in the presence of an m = n = 1 island, may give rise to magnetic field line stochastization and thereby contribute significantly to a rapid expulsion of electronic energy from the plasma core region. Second, the so-called precursor oscillations prior to a sawtooth crash have been investigated and estimates have been obtained for the growth rate and width of a magnetic island forming immediately before the collapse. (Author)

  15. Electrostatic quasi-monochromatic waves in the downstream region of the Earth's bow shock based on Geotail observations

    Science.gov (United States)

    Shin, K.; Kojima, H.; Matsumoto, H.; Mukai, T.

    2007-02-01

    Geotail plasma wave observations show the existence of intense electrostatic quasi-monochromatic (EQM) waves in the downstream region of the Earth's bow shock. They oscillate parallel to the ambient magnetic field and appear at frequencies between the electron plasma and ion plasma frequencies. Although these waves have been believed to be Doppler-shifted ion acoustic waves, the typical plasma parameters observed in the downstream region do not support the generation conditions for ion acoustic waves. In this paper, the existence of cold electron beam-like components accompanying EQM waves is considered based on waveform and statistical analyses. Linear dispersion analyses using realistic plasma parameters revealed that the cold electron beams cause destabilization of electron acoustic waves at frequencies consistent with those of observed EQM waves. The results of observations and linear analyses suggest that EQM waves are generated by the destabilization of the electron acoustic mode.

  16. Preliminary study of cross-field plasma injection in 2XIIB

    International Nuclear Information System (INIS)

    Cheng, D.Y.; Hartman, C.W.; Simonen, T.C.

    1978-01-01

    Preliminary results are presented of a study of cross-field plasma injection in the 2XIIB mirror machine. Plasma accelerated by a coaxial deflagration gun was observed to pass 3.5M across the vacuum field, and some trapping was observed when the gun plasma intersected a plasma streaming along B at the center of the magnetic well. Parameters for the experiment are: gun plasma kinetic energy 50 to 200 eV, n/sub gun/ = 3 x 10 13 cm -3 , streaming plasma 25 to 50 eV and n/sub streaming/ = 6 x 10 11 cm -3 , duration of both 100 to 200 μsec. For the trapped plasma, n = 2.4 x 10 12 cm -3 , and the decay time is t/sub 1 / 2 / = 400 μsec consistent with Coulomb scattering loss at 100 eV mean ion energy

  17. Observation of ion-acoustic rarefaction solitons in a multicomponent plasma with negative ions

    International Nuclear Information System (INIS)

    Ludwig, G.O.; Ferreira, J.L.; Nakamura, Y.

    1984-01-01

    The propagation of ion-acoustic solitons in a plasma with negative ions has been observed. For sufficiently large concentration of negative ions, applied rarefactive (negative) voltage pulses break up into solitons, whereas compressive pulses evolve into wave trains, with exactly the opposite behavior as that for a plasma composed only of positive ions. There is a critical value of the negative-ion concentration for which a finite-amplitude pulse propagates without steepening

  18. Comparing UV/EUV line parameters and magnetic field in a quiescent prominence with tornadoes

    Science.gov (United States)

    Levens, P. J.; Labrosse, N.; Schmieder, B.; López Ariste, A.; Fletcher, L.

    2017-10-01

    Context. Understanding the relationship between plasma and the magnetic field is important for describing and explaining the observed dynamics of solar prominences. Aims: We determine if a close relationship can be found between plasma and magnetic field parameters, measured at high resolution in a well-observed prominence. Methods: A prominence observed on 15 July 2014 by the Interface Region Imaging Spectrograph (IRIS), Hinode, the Solar Dynamics Observatory (SDO), and the Télescope Héliographique pour l'Étude du Magnétisme et des Instabilités Solaires (THEMIS) is selected. We perform a robust co-alignment of data sets using a 2D cross-correlation technique. Magnetic field parameters are derived from spectropolarimetric measurements of the He I D3 line from THEMIS. Line ratios and line-of-sight velocities from the Mg II h and k lines observed by IRIS are compared with magnetic field strength, inclination, and azimuth. Electron densities are calculated using Fe xii line ratios from the Hinode Extreme-ultraviolet Imaging Spectrometer, which are compared to THEMIS and IRIS data. Results: We find Mg II k/h ratios of around 1.4 everywhere, similar to values found previously in prominences. Also, the magnetic field is strongest ( 30 G) and predominantly horizontal in the tornado-like legs of the prominence. The k3 Doppler shift is found to be between ±10 km s-1 everywhere. Electron densities at a temperature of 1.5 × 106 K are found to be around 109 cm-3. No significant correlations are found between the magnetic field parameters and any of the other plasma parameters inferred from spectroscopy, which may be explained by the large differences in the temperatures of the lines used in this study. Conclusions: This is the first time that a detailed statistical study of plasma and magnetic field parameters has been performed at high spatial resolution in a prominence. Our results provide important constraints on future models of the plasma and magnetic field in

  19. Relativistic effects in hydrogenlike atoms embedded in Debye plasmas

    International Nuclear Information System (INIS)

    Bielinska-Waz, D.; Karwowski, J.; Saha, B.; Mukherjee, P.K.

    2004-01-01

    Spectra of hydrogenlike atoms embedded in a Debye plasma are investigated. The state energies and the transition rates are studied using a fully relativistic formalism based on the Dirac equation. The effect of the plasma is described by introducing an exponential screening to the nuclear Coulomb potential (the Debye screening). Systematic trends with respect to both the nuclear charge and the screening parameter are observed for all calculated quantities. The pattern of splittings of ns 1/2 , np 1/2 and np 3/2 is modified in a specific way due to the combined relativity and plasma effect. The transition rates decrease with an increase of the Debye parameter as well as with an increase of Z

  20. ULF waves and plasma stability in different regions of the magnetosheath

    Science.gov (United States)

    Soucek, Jan; Escoubet, C. Philippe; Grison, Benjamin

    2016-04-01

    We present a statistical study of the occurrence and properties of ultra low frequency waves in the magnetosheath and interpret the results in terms of the competition of mirror and Alfvén-ion-cyclotron (AIC) instabilities. Both mirror and AIC waves are generated in high beta plasma of the magnetosheath when ion temperature anisotropy exceeds the threshold of the respective instabilities. These waves are frequently observed in the terrestrial and planetary magnetosheaths, but their distribution within the magnetosheath is inhomogeneous and their character varies as a function of location, local and upstream plasma parameters. We studied the spatial distribution of the two wave modes in the magnetosheath together with the local plasma parameters important for the stability of ULF waves. This analysis was performed on a dataset of all magnetosheath crossings observed by Cluster spacecraft over two years. For each observation we used bow shock, magnetopause and magnetosheath flow models to identify the relative position of the spacecraft with respect to magnetosheath boundaries and local properties of the upstream shock crossing. A strong dependence of parameters characterizing plasma stability and mirror/AIC wave occurrence on upstream ΘBn and MA is identified. The occurrence of mirror and AIC modes was compared against the respective instability thresholds and it was observed that AIC waves occurred nearly exclusively under mirror stable conditions. This is interpreted in terms of the different character of non-linear saturation of the two modes.

  1. Double plasma system with inductively coupled source plasma and quasi-quiescent target plasma

    International Nuclear Information System (INIS)

    Massi, M.; Maciel, H.S.

    1995-01-01

    Cold plasmas have successfully been used in the plasma-assisted material processing industry. An understanding of the physicochemical mechanisms involved in the plasma-surface interaction is needed for a proper description of deposition and etching processes at material surfaces. Since these mechanisms are dependent on the plasma properties, the development of diagnostic techniques is strongly desirable for determination of the plasma parameters as well as the characterization of the electromagnetic behaviour of the discharge. In this work a dual discharge chamber, was specially designed to study the deposition of thin films via plasma polymerization process. In the Pyrex chamber an inductively coupled plasma can be excited either in the diffuse low density E-mode or in the high density H-mode. This plasma diffuses into the cylindrical stainless steel chamber which is covered with permanent magnets to produce a multidipole magnetic field configuration at the surface. By that means a double plasma is established consisting of a RF source plasma coupled to a quasi-quiescent target plasma. The preliminary results presented here refer to measurements of the profiles of plasma parameters along the central axis of the double plasma apparatus. Additionally a spectrum analysis performed by means of a Rogowski coil probe immersed into the source plasma is also presented. The discharge is made in argon with pressure varying from 10 -2 to 1 torr, and the rf from 10 to 150 W

  2. Experimental observations of the plasma properties of a high-density, low-temperature accelerated arc

    International Nuclear Information System (INIS)

    Thomas, K.A.

    1991-01-01

    The existence of an absorbing layer, or buffer zone, of weakly ionized gas between the rear of the projectile and the front of the plasma arc armature in a plasma accelerator was demonstrated. A technique was developed to accurately determine the position of the projectile as it accelerates along the bore of the device. The projectile position is compared to that of the plasma arc as measured by magnetic field probes. These measurements provide the basis for a description of the in-bore motion of the projectile with respect to the plasma arc. Observations of this motion in plasma accelerators of 0.6 and 2.4 m lengths show the buffer zone can be as large as 50 times the bore diameter. In-bore measurements of the broadband light emission and pressure of both the buffer region and the plasma arc armature are correlated with the known projectile position to determine the characteristics of both the buffer zone and the plasma arc. Time-integrated spectral measurements of the emission taken through both the side insulators and the electrodes indicate the existence of a nonuniform plasma temperature and of turbulence in the plasma. The presence of molecular species is attributed with the ablation of the side insulator material

  3. Plasma end-loss studies on Scylla I-C

    International Nuclear Information System (INIS)

    McKenna, K.F.; York, T.M.

    1976-08-01

    The end-loss process in the collision dominated Scylla I-C plasma has been investigated with a local pressure sensitive diagnostic, integrated density measurement and axially arrayed diamagnetic loop probes. The development of a plasma loss orifice, well within the theta-pinch coil, has been identified. The magnitude of the observed orifice is found to be in excellent agreement with that predicted from collisional MHD theories. The axially flowing plasma is well confined until it flows through the loss orifice. After passing through the orifice, rapid axial expansion is observed. An indication of the existence of inward traveling rarefaction waves has been observed from the plasma midplane temperature data; an abrupt decrease in the plasma temperature at t approximately equal to 6.5 μs corresponds to the predicted time of arrival of rarefaction waves at the coil midplane. The plasma loss rate derived from the pressure data indicates an initial period (t 4 μs) of gradual decay in the loss rate. This initial period of high loss rate is predicted from the MHD flow theories when the measured, time dependent plasma parameters are substituted into the analytical models. The loss rate determined from the end-on interferograms does not respond to the detailed structure of the plasma loss process

  4. Occurrence of high-beta superthermal plasma events in the close environment of Jupiter's bow shock as observed by Ulysses

    International Nuclear Information System (INIS)

    Marhavilas, P. K.; Sarris, E. T.; Anagnostopoulos, G. C.

    2011-01-01

    The ratio of the plasma pressure to the magnetic field pressure (or of their energy densities) which is known as the plasma parameter 'beta'(β) has important implications to the propagation of energetic particles and the interaction of the solar wind with planetary magnetospheres. Although in the scientific literature the contribution of the superthermal particles to the plasma pressure is generally assumed negligible, we deduced, by analyzing energetic particles and magnetic field measurements recorded by the Ulysses spacecraft, that in a series of events, the energy density contained in the superthermal tail of the particle distribution is comparable to or even higher than the energy density of the magnetic field, creating conditions of high-beta plasma. More explicitly, in this paper we analyze Ulysses/HI-SCALE measurements of the energy density ratio (parameter β ep ) of the energetic ions'(20 keV to ∼5 MeV) to the magnetic field's in order to find occurrences of high-beta (β ep >1) superthermal plasma conditions in the environment of the Jovian magnetosphere, which is an interesting plasma laboratory and an important source of emissions in our solar system. In particular, we examine high-beta ion events close to Jupiter's bow shock, which are produced by two processes: (a) bow shock ion acceleration and (b) ion leakage from the magnetosphere.

  5. Nonlinear Adaptive Descriptor Observer for the Joint States and Parameters Estimation

    KAUST Repository

    2016-08-29

    In this note, the joint state and parameters estimation problem for nonlinear multi-input multi-output descriptor systems is considered. Asymptotic convergence of the adaptive descriptor observer is established by a sufficient set of linear matrix inequalities for the noise-free systems. The noise corrupted systems are also considered and it is shown that the state and parameters estimation errors are bounded for bounded noises. In addition, if the noises are bounded and have zero mean, then the estimation errors asymptotically converge to zero in the mean. The performance of the proposed adaptive observer is illustrated by a numerical example.

  6. Nonlinear Adaptive Descriptor Observer for the Joint States and Parameters Estimation

    KAUST Repository

    Unknown author

    2016-01-01

    In this note, the joint state and parameters estimation problem for nonlinear multi-input multi-output descriptor systems is considered. Asymptotic convergence of the adaptive descriptor observer is established by a sufficient set of linear matrix inequalities for the noise-free systems. The noise corrupted systems are also considered and it is shown that the state and parameters estimation errors are bounded for bounded noises. In addition, if the noises are bounded and have zero mean, then the estimation errors asymptotically converge to zero in the mean. The performance of the proposed adaptive observer is illustrated by a numerical example.

  7. Demeter high resolution observations of the ionospheric thermal plasma response to magnetospheric energy input during the magnetic storm of November 2004

    Directory of Open Access Journals (Sweden)

    E. Séran

    2007-01-01

    Full Text Available High resolution Demeter plasma and wave observations were available during one of the geomagnetic storms of November 2004 when the ionospheric footprint of the plasmasphere was pushed below 64 degrees in the midnight sector. We report here onboard observations of thermal/suprathermal plasma and HF electric field variations with a temporal resolution of 0.4 s, which corresponds to a spatial resolution of 3 km. Local perturbations of the plasma parameters at the altitude of 730 km are analysed with respect to the variation of the field-aligned currents, electron and proton precipitation and large-scale electric fields, measured in-situ by Demeter and by remote optical methods from the IMAGE/Polar satellites. Flow monitoring in the 21:00 and 24:00 MLT sectors during storm conditions reveals two distinct regions of O+ outflow, i.e. the region of the field-aligned currents, which often comprises few layers of opposite currents, and the region of velocity reversal toward dusk at sub-auroral latitudes. Average upward O+ velocities are identical in both local time sectors and vary between 200 and 450 m s−1, with an exception of a few cases of higher speed (~1000 m s−1 outflow, observed in the midnight sector. Each individual outflow event does not indicate any heating process of the thermal O+ population. On the contrary, the temperature of the O+, outflowing from auroral latitudes, is found to be even colder than that of the ambient ion plasma. The only ion population which is observed to be involved in the heating is the O+ with energies a few times higher than the thermal energy. Such a population was detected at sub-auroral latitudes in the region of duskward flow reversal. Its temperature raises up to a few eV inside the layer of sheared velocity. A deep decrease in the H+ density at heights and latitudes, where, according to the IRI model, these ions are expected to comprise ~50% of the positive charge, indicates that the thermospheric balance

  8. Parameter Identification and Synchronization of Uncertain Chaotic Systems Based on Sliding Mode Observer

    Directory of Open Access Journals (Sweden)

    Li-lian Huang

    2013-01-01

    Full Text Available The synchronization of nonlinear uncertain chaotic systems is investigated. We propose a sliding mode state observer scheme which combines the sliding mode control with observer theory and apply it into the uncertain chaotic system with unknown parameters and bounded interference. Based on Lyapunov stability theory, the constraints of synchronization and proof are given. This method not only can realize the synchronization of chaotic systems, but also identify the unknown parameters and obtain the correct parameter estimation. Otherwise, the synchronization of chaotic systems with unknown parameters and bounded external disturbances is robust by the design of the sliding surface. Finally, numerical simulations on Liu chaotic system with unknown parameters and disturbances are carried out. Simulation results show that this synchronization and parameter identification has been totally achieved and the effectiveness is verified very well.

  9. Parametric studies in a small plasma focus device

    International Nuclear Information System (INIS)

    Chuaqui, H.; Favre, M.; Silva, P.; Wyndham, E.

    1996-01-01

    Very high temperature and density plasmas can be produced in modest size plasma focus devices at the kJ level. Much of the scaling parameters on the plasma focus have been evaluated, though many questions still remain. The modest cost and simple construction allows easy modification to the device and the discharge parameters. In this paper the authors report on a small plasma focus device, which is set-up to investigate the effect of some of those modifications on the plasma, with detailed experimental diagnostics. Experiments have been carried out in various gases and with mixtures of different ratios. Extended operating range from below 0.5 torr upwards has been achieved with the implementation of the auxiliary discharge circuit. Despite the low voltage and low energy operation, energetic beam formation has been observed at the time of the final compression, prior to disruption. Current sheath formation and evolution has been characterized using the magnetic probes array, in correlation with beam formation and plasma emission. The relationship of the current sheath structure and that of the pinched plasma, as shown by the filtered X-ray pinhole camera, has been investigated

  10. Monitoring of plasma butyrylcholinesterase activity and hematological parameters in pesticide sprayers

    OpenAIRE

    Rastogi, S. K.; Singh, Vipul K.; Kesavachandran, C.; Jyoti,; Siddiqui, M. K. J.; Mathur, N.; Bharti, R. S.

    2008-01-01

    To evaluate the health impact of spraying organophosphorus insecticides (OPs), 34 male sprayers in the mango belt of Malihabad, a small town located 27 km from Lucknow in North India was selected. Plasma butyryl cholinesterase (PBChE) and complete blood count were assessed among sprayers after spraying pesticides and the findings obtained were compared with those determined in a reference group ( n = 18). The most common symptoms observed were burning sensation in the eyes (8.82%), it...

  11. A model for steady-state large-volume plasma generation

    International Nuclear Information System (INIS)

    Uhm, H.S.; Miller, J.D.; Schneider, R.F.

    1991-01-01

    In this paper, a simple, new scheme to generate a uniform, steady-state, large-volume plasma is presented. The weakly magnetized plasma is created by direct ionization of the background gas by low-energy electrons generated from thermionic filaments. An annular arrangement of the filaments ensures a uniform plasma density in the radial direction as predicted by theory. Experiments have been performed to characterize the plasma generated in such a configuration. In order to explain the experimental observation, we develop a bulk plasma theory based on plasma transport via cross-field diffusion. As assumed in the theoretical model, the experimental measurements indicate a uniform plasma density along the axis. Both the theory and experiment indicate that the plasma density is a function of the square of the external magnetic field. The theory also predicts the plasma density to be proportional to the neutral density to the two-thirds power in agreement with the experimental data. We also observe the experimental data to agree remarkably well with theoretical prediction for a broad range of system parameters

  12. Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with neon

    International Nuclear Information System (INIS)

    Malinina, A. A.; Malinin, A. N.

    2013-01-01

    Results are presented from studies of the optical characteristics and parameters of plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with neon—the working medium of a non-coaxial exciplex gas-discharge emitter. The electron energy distribution function, the transport characteristics, the specific power losses for electron processes, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering by the working mixture components are determined as functions of the reduced electric field. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules is found to be 1.6 × 10 −14 m 3 /s for a reduced electric field of E/N = 15 Td, at which the maximum emission intensity in the blue-green spectral region (λ max = 502 nm) was observed in this experiment

  13. Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with neon

    Energy Technology Data Exchange (ETDEWEB)

    Malinina, A. A., E-mail: alexandr_malinin@rambler.ru; Malinin, A. N. [Uzhhorod National University (Ukraine)

    2013-12-15

    Results are presented from studies of the optical characteristics and parameters of plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with neon—the working medium of a non-coaxial exciplex gas-discharge emitter. The electron energy distribution function, the transport characteristics, the specific power losses for electron processes, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering by the working mixture components are determined as functions of the reduced electric field. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules is found to be 1.6 × 10{sup −14} m{sup 3}/s for a reduced electric field of E/N = 15 Td, at which the maximum emission intensity in the blue-green spectral region (λ{sub max} = 502 nm) was observed in this experiment.

  14. MMS Observations of Protons and Heavy Ions Acceleration at Plasma Jet Fronts

    Science.gov (United States)

    Catapano, F.; Retino, A.; Zimbardo, G.; Cozzani, G.; Breuillard, H.; Le Contel, O.; Alexandrova, A.; Mirioni, L.; Cohen, I. J.; Turner, D. L.; Perri, S.; Greco, A.; Mauk, B.; Torbert, R. B.; Russell, C. T.; Khotyaintsev, Y. V.; Lindqvist, P. A.; Ergun, R.; Giles, B. L.; Fuselier, S. A.; Moore, T. E.; Burch, J.

    2017-12-01

    Plasma jet fronts in the Earth's magnetotail are kinetic-scale boundaries separating hot fast plasma jets, generally attributed to reconnection outflows, from colder ambient plasma. Jet fronts are typically associated with a sharp increase of the vertical component of the magnetic field Bz, an increase of the plasma temperature and a drop of plasma density. Spacecraft observations and numerical simulations indicate that jet fronts are sites of major ion acceleration. The exact acceleration mechanisms as well as the dependence of such mechanisms on ion composition are not fully understood, yet. Recent high-resolution measurements of ion distribution functions in the magnetotail allow for the first time to study the acceleration mechanisms in detail. Here, we show several examples of jet fronts and discuss ion acceleration therein. We show fronts that propagate in the mid-tail magnetotail both as isolated laminar boundaries and as multiple boundaries embedded in strong magnetic fluctuations and turbulence. We also show fronts in the near-Earth jet braking region, where they interact with the dipolar magnetic field and are significantly decelerated/diverted. Finally, we study the acceleration of different ion species (H+, He++, O+) at different types of fronts and we discuss possible different acceleration mechanisms and how they depend on the ion species.

  15. Dust-acoustic instability in an inductive gas-discharge plasma

    International Nuclear Information System (INIS)

    Zobnin, A.V.; Usachev, A.D.; Petrov, O.F.; Fortov, V.E.

    2002-01-01

    Spontaneous excitation of a dust-particle density wave is observed in a dust cloud levitating in the region of the diffused edge of an rf inductive low-pressure gas-discharge plasma. The main physical parameters of this wave and of the background plasma are measured. The analytic model proposed for the observed phenomenon is based on the theory of dust sound and successfully correlates with experimental data in a wide range of experimental conditions. The effect of variable charge of dust particles on the evolution of the observed dust-plasma instability is studied analytically. It is shown that the necessary condition for the development of the dust-acoustic instability is the presence of a dc electric field in the dust cloud region

  16. Determination of discharge parameters via OES at the Linac4 H− ion source

    International Nuclear Information System (INIS)

    Briefi, S.; Fink, D.; Mattei, S.; Lettry, J.; Fantz, U.

    2016-01-01

    Optical emission spectroscopy (OES) measurements of the atomic Balmer series and the molecular Fulcher transition have been carried out at the Linac4 ion source in order to determine plasma parameters. As the spectroscopic system was only relatively calibrated, the data evaluation only yielded rough estimates of the plasma parameters (T e ≈ 1.2 eV, n e ≈ 1 × 10 19 m −3 , and n H /n H 2 ≈ 0.5 at standard operational parameters). The analysis of the Fulcher transition revealed a non-thermal “hockey-stick” rotational population of the hydrogen molecules. At varying RF power, the measurements at the on-axis line of sight (LOS) showed a peak in the rotational temperatures between 25 and 40 kW of RF power, whereas a steady decrease with power was observed at a tilted LOS, indicating the presence of strong plasma parameter gradients

  17. Observations of plasma rotation in the high-beta tokamak Torus II

    International Nuclear Information System (INIS)

    Kostek, C.; Marshall, T.C.

    1982-01-01

    Toroidal and poloidal plasma rotation are measured in a high Beta tokamak device by studying the Doppler shift of the 4686 A He II line. The toroidal flow motion is in the same direction as the plasma current at an average velocity of 1.6 x 10 6 cm/sec, a small fraction of the ion thermal speed. The poloidal flow follows the ion diamagnetic direction, also at an average speed of 1.6 x 10 6 cm/sec. In view of certain ordering parameters, the toroidal flow is compared with the predictions of neoclassical transport theory in the collisional regime. For the poloidal motion, however, it appears that an (E/sub r/ x B)/B 2 drift in a positive radial electric field, approaching a stable ambipolar state (STRINGER, 1970) is responsible. Mechanisms for the time evolution of the rotation are also examined. The radial electric field responsible for the (E/sub r/ x B)/B 2 drift is determined from the theory using the measured poloidal velocity

  18. On the identifiability of linear dynamical systems. [parameters observation in presence of white noise

    Science.gov (United States)

    Glover, K.; Willems, J. C.

    1973-01-01

    Consider the situation in which the unknown parameters of a stationary linear system may be parametrized by a set of unknown parameters. The question thus arises of when such a set of parameters can be uniquely identified on the basis of observed data. This problem is considered here both in the case of input and output observations and in the case of output observations in the presence of a white noise input. Conditions for local identifiability are derived for both situations and a sufficient condition for global identifiability is given for the former situation, i.e., when simultaneous input and output observations are available.

  19. Observation of Ion Acoustic Waves Excited by Drift Waves in a Weakly Magnetized Plasma

    International Nuclear Information System (INIS)

    Tsukabayashi, Isao; Sato, Sugiya; Nakamura, Yoshiharu

    2003-01-01

    Spontaneous fluctuations excited by drift waves are investigated experimentally in magnetic multi-pole plasma. The magnetic multi-pole has been widely used in DP devices and so on. It was observed that the high level of density fluctuations was generated by the drift instability near a magnetic multi-pole or a dipole magnet. The waves propagate to the middle plasma region forming the envelope train waves

  20. Determination of reference ranges for full blood count parameters in neonatal cord plasma in Hilla, Babil, Iraq

    Directory of Open Access Journals (Sweden)

    Al-Marzoki JM

    2012-10-01

    Full Text Available Jasim M Al-Marzoki1, Zainab W Al-Maaroof2, Ali H Kadhum31Department of Pediatrics, 2Department of Pathology, Babylon Medical College, 3Babylon Gynecology and Pediatric Teaching Hospital, Hilla, IraqBackground: The health of an individual is known to vary in different countries, in the same country at different times, and in the same individuals at different ages. This means that the condition of individuals must be related to or compared with reference data. Determination of a reference range for the healthy term newborn is clinically important in terms of various complete blood count parameters. The purpose of this study was to establish a local reference range for full blood count parameters in neonatal cord plasma in Hilla, Babil, Iraq.Methods: A total of 220 mothers and their neonates were enrolled in this cross-sectional study from February 2011 to January 2012. Maternal inclusion criteria were age 15–45 years, an uneventful pregnancy, and hemoglobin ≥ 10 g. Neonatal inclusion criteria were full term (37–42 weeks and normal birth weight. The umbilical cord was immediately clamped after delivery of the baby; 3 mL of cord blood was then taken from the umbilical vein and collected in a tube containing ethylenediamine tetra-acetic acid, its plasma was analyzed for full blood count parameters by standard Coulter gram, and the differential leukocyte count was done manually.Results: Mean neonatal hemoglobin was 13.88 ± 1.34 (range 11–17.3 g/dL and mean white cell count was 10.12 ± 2.8 (range 3.1–21.6 × 109/L. Mean platelet count was 267.63 ± 60.62 (range 152–472 × 109/L. No significant differences in red cell, white cell, or platelet counts were found between males and females, except for neutrophil count. The current study shows lower levels of hemoglobin, white cells, and red cells compared with other studies, and there is agreement with some studies and disagreement with others concerning platelet count.Conclusion: Most results

  1. Non-thermal plasma mills bacteria: Scanning electron microscopy observations

    International Nuclear Information System (INIS)

    Lunov, O.; Churpita, O.; Zablotskii, V.; Jäger, A.; Dejneka, A.; Deyneka, I. G.; Meshkovskii, I. K.; Syková, E.; Kubinová, Š.

    2015-01-01

    Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanning electron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin–stained rat skin sections from plasma–treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy

  2. Hypervelocity dust particle impacts observed by the Giotto magnetometer and plasma experiments

    Science.gov (United States)

    Neubauer, F. M.; Glassmeier, K.-H.; Coates, A. J.; Goldstein, R.; Acuna, M. H.

    1990-01-01

    This paper describes 13 very short events in the magnetic field of the inner magnetic pile-up region of Comet Halley observed by the Giotto magnetometer experiment together with simultaneous plasma data obtained by the Johnstone plasma analyzer and the ion mass spectrometer experiments. The events are due to dust impacts in the milligram range on the spacecraft at the relative velocity between the cometary dust and the spacecraft of 68 km/sec. They are generally consistent with dust impact events derived from spacecraft attitude perturbations by the Giotto camera. Their characteristic shape generally involves a sudden decrease in magnetic-field magnitude, a subsequent overshoot beyond initial field values, and an asymptotic approach to the initial field (somewhat reminiscent of the magnetic-field signature after the AMPTE releases in the solar wind). These observations give a new way of analyzing ultra-fast dust particles incident on a spacecraft.

  3. Geometry of solar corona expansion and solar wind parameters

    International Nuclear Information System (INIS)

    Krajnev, M.B.

    1980-01-01

    The character of the parameter chanqe of solar wind plasma in the region of the Earth orbit is studied. The main regularities in the parametep behaviour of solar wind (plasma velocity and density) are qualitatively explained in the framework of a model according to which solar corona expansion stronqly differs from radial expansion, that is: the solar wind current lines are focused towards helioequator during the period of low solar activity with gradual transfer to radial expansion during the years of high solar activity. It is shown that the geometry of the solar wind current tubes and its change with the solar activity cycle can not serve an explanation of the observed change of the solar wind parameters

  4. ℋ- adaptive observer design and parameter identification for a class of nonlinear fractional-order systems

    KAUST Repository

    Ndoye, Ibrahima

    2014-12-01

    In this paper, an adaptive observer design with parameter identification for a nonlinear system with external perturbations and unknown parameters is proposed. The states of the nonlinear system are estimated by a nonlinear observer and the unknown parameters are also adapted to their values. Sufficient conditions for the stability of the adaptive observer error dynamics are derived in terms of linear matrix inequalities. Simulation results for chaotic Lorenz systems with unknown parameters in the presence of external perturbations are given to illustrate the effectiveness of our proposed approach. © 2014 IEEE.

  5. Observations of nonlinear behaviour in a low-pressure discharge column

    International Nuclear Information System (INIS)

    Cartier, S.L.; Merlino, R.L.

    1984-01-01

    Sudden and abrupt jumps in the plasma density and discharge current of low-pressure magnetized argon and helium plasmas are observed. These jumps are found to depend on the discharge bias voltage, the neutral gas pressure, and the magnetic field strength and occur with a substantial hysteresis in those parameters. These jumps are accompanied by the onset of intense and coherent low-frequency plasma oscillations. In addition, under certain conditions, the radial density profile of the plasma is found to be significantly different following a jump. Some possibly related plasma instabilities are discussed

  6. Experimental observation of the inductive electric field and related plasma nonuniformity in high frequency capacitive discharge

    International Nuclear Information System (INIS)

    Ahn, S. K.; Chang, H. Y.

    2008-01-01

    To elucidate plasma nonuniformity in high frequency capacitive discharges, Langmuir probe and B-dot probe measurements were carried out in the radial direction in a cylindrical capacitive discharge driven at 90 MHz with argon pressures of 50 and 400 mTorr. Through the measurements, a significant inductive electric field (i.e., time-varying magnetic field) was observed at the radial edge, and it was found that the inductive electric field creates strong plasma nonuniformity at high pressure operation. The plasma nonuniformity at high pressure operation is physically similar to the E-H mode transition typically observed in inductive discharges. This result agrees well with the theories of electromagnetic effects in large area and/or high frequency capacitive discharges

  7. Self-sustained oscillations in the divertor plasma

    International Nuclear Information System (INIS)

    Krasheninnikov, S.I.; Kukushkin, A.S.; Pistunovich, V.I.; Pozharov, V.A.

    1985-01-01

    A simple analytical model of the edge plasma with high recycling, which relays on the presence of a small parameter - the ratio of the particle flows crossing the magnetic field to those impinging onto the divertor target, is proposed. A concept of the one-dimensional steady state (OSS) is introduced as the zero approximation in the small parameter. The mean number density N-tilde of the particles - ions plus neutrals - in the magnetic flux tube is choosen as the most representative and convenient parameter of the problem. The OSS are shown to be ambiguous in some N-tilde range for sufficiently high values of the energy flow entering the scrape-off layer from the bulk plasma. An equation, that describes a quasi-steady variations in OSS, is derived and a mechanism of exciting the self-sustained oscillations is developed. Results of simulation of the edge plasma oscillations are found to be in a good agreement with this mechanism, which could be responsible for the H-mode oscillations observed in the divertor experiments

  8. Titan's plasma environment: 3D hybrid simulation and comparison with observations

    Science.gov (United States)

    Lipatov, A. S.; Sittler, E. C.; Hartle, R. E.

    2007-12-01

    A multiscale combined (fluid--kinetic) numerical method allows us to use more realistic plasma models at Titan. This method takes into account charge-exchange and photoionization processes. We study the Titan's plasma environment in case of high, intermediate and low exosphere density in Chamberlain models. The background ions H+, O+ and pickup ions H2+, CH4+ and N2+ are described in a kinetic approximation, where the electrons are approximated as a fluid. We also include an immobile ionosphere at the height 1300km. In this report we consider the multiscale spatial structure for plasma and electromagnetic field, and the velocity distribution of ions that results from the coupling between background ions and pickup ions. Special attention will be paid for the comparisons our numerical results with Voyager and Cassini observations (see e.g. [Sittler, Hartle, et al., 2005; Hartle, Sittler et al., 2006]). We shall estimate of mass loading rate for Ta, energy input to upper atmosphere from ambient +pickup ions, and the T9 encounter with two crossings. \

  9. Design of an Experiment to Observe Laser-Plasma Interactions on NIKE

    Science.gov (United States)

    Phillips, L.; Weaver, J.; Manheimer, W.; Zalesak, S.; Schmitt, A.; Fyfe, D.; Afeyan, B.; Charbonneau-Lefort, M.

    2007-11-01

    Recent proposed designs (Obenschain et al., Phys. Plasmas 13 056320 (2006)) for direct-drive ICF targets for energy applications involve high implosion velocities combined with higher laser irradiances. The use of high irradiances increases the likelihood of deleterious laser plasma instabilities (LPI) that may lead, for example, to the generation of fast electrons. The proposed use of a 248 nm KrF laser to drive these targets is expected to minimize LPI; this is being studied by experiments at NRL's NIKE facility. We used a modification of the FAST code that models laser pulses with arbitrary spatial and temporal profiles to assist in designing these experiments. The goal is to design targets and pulseshapes to create plasma conditions that will produce sufficient growth of LPI to be observable on NIKE. Using, for example, a cryogenic DT target that is heated by a brief pulse and allowed to expand freely before interacting with a second, high-intensity pulse, allows the development of long scalelengths at low electron temperatures and leads to a predicted 20-efold growth in two-plasmon amplitude.

  10. Response of the plasma to the size of an anode electrode biased near the plasma potential

    International Nuclear Information System (INIS)

    Barnat, E. V.; Laity, G. R.; Baalrud, S. D.

    2014-01-01

    As the size of a positively biased electrode increases, the nature of the interface formed between the electrode and the host plasma undergoes a transition from an electron-rich structure (electron sheath) to an intermediate structure containing both ion and electron rich regions (double layer) and ultimately forms an electron-depleted structure (ion sheath). In this study, measurements are performed to further test how the size of an electron-collecting electrode impacts the plasma discharge the electrode is immersed in. This is accomplished using a segmented disk electrode in which individual segments are individually biased to change the effective surface area of the anode. Measurements of bulk plasma parameters such as the collected current density, plasma potential, electron density, electron temperature and optical emission are made as both the size and the bias placed on the electrode are varied. Abrupt transitions in the plasma parameters resulting from changing the electrode surface area are identified in both argon and helium discharges and are compared to the interface transitions predicted by global current balance [S. D. Baalrud, N. Hershkowitz, and B. Longmier, Phys. Plasmas 14, 042109 (2007)]. While the size-dependent transitions in argon agree, the size-dependent transitions observed in helium systematically occur at lower electrode sizes than those nominally derived from prediction. The discrepancy in helium is anticipated to be caused by the finite size of the interface that increases the effective area offered to the plasma for electron loss to the electrode

  11. Mercury-free electrodeless discharge lamp: effect of xenon pressure and plasma parameters on luminance

    International Nuclear Information System (INIS)

    Nazri Dagang Ahmad; Kondo, Akira; Motomura, Hideki; Jinno, Masafumi

    2009-01-01

    Since there is much concern about environmental preservation, the authors have paid attention to the uses of mercury in lighting application. They have focused on the application of the xenon low-pressure inductively coupled plasma (ICP) discharge in developing cylindrical type mercury-free light sources. ICP can be operated at low filling gas pressures and demonstrates significant potential in producing high density plasma. Xenon pressure was varied from 0.1 to 100 Torr and the lamp luminance was measured. The gas pressure dependence shows an increase in luminance at pressures below 1 Torr. In order to clarify this behaviour, measurement of plasma parameters was carried out using the double probe method and its relation to lamp luminance is discussed. As the gas pressure is decreased (from 1 to 0.01 Torr), the electron temperature increases while the electron density decreases while at the same time the lamp luminance increases. There are several factors that are believed to contribute to the increase in luminance in the very low pressure region. Increases in luminance are considered to be due to the electron-ion recombination process which brings a strong recombination radiation in continuum in the visible region and also due to the effect of stochastic heating.

  12. Boundary plasma control with the ergodic divertor

    International Nuclear Information System (INIS)

    Ghendrih, Ph.; Becoulet, M.; Beyer, P.

    1999-01-01

    Ergodic divertor experiments on Tore Supra provide evidence of significant control of plasma-wall interaction. Theoretical investigation of the laminar region (i.e. governed by parallel transport) indicates that control of the plasma state at the target plate can be achieved with plasma states similar to that observed with the axisymmetric divertor. Analysis of the temperature field with a 2-D test particle code allows one to recover the observed spatial modulation and shows that an intrinsic barrier appears to develop at the separatrix. Energy deposition peaking, analysed with a 3-D code, is strongly reduced when moderate transverse transport is considered. Possible control of upstream parameters can thus be achieved in the ergodic region, for instance a lowering of the parallel energy flux by cross field transport. (author)

  13. Boundary plasma control with the ergodic divertor

    International Nuclear Information System (INIS)

    Ghendrih, Ph.; Becoulet, M.; Beyer, P.

    2001-01-01

    Ergodic divertor experiments on Tore Supra provide evidence of significant control of plasma-wall interaction. Theoretical investigation of the laminar region (i.e. governed by parallel transport) indicates that control of the plasma state at the target plate can be achieved with plasma states similar to that observed with the axisymmetric divertor. Analysis of the temperature field with a 2-D test particle code allows one to recover the observed spatial modulation and shows that an intrinsic barrier appears to develop at the separatrix. Energy deposition peaking, analysed with a 3-D code, is strongly reduced when moderate transverse transport is considered. Possible control of upstream parameters can thus be achieved in the ergodic region, for instance a lowering of the parallel energy flux by cross field transport. (author)

  14. A dynamic state observer for real-time reconstruction of the tokamak plasma profile state and disturbances

    NARCIS (Netherlands)

    Felici, F.; De Baar, M.; Steinbuch, M.

    2014-01-01

    A dynamic observer is presented which can reconstruct the internal state of a tokamak fusion plasma, consisting of the spatial distribution of current and temperature, from measurements. Today, the internal plasma state is usually reconstructed by solving an ill-conditioned inversion problem using a

  15. Influence of laser design parameters on the hydrodynamics of microfusion plasmas; Influencia de los parametros basicos del laser sobre la hidrodinamica de plasmas para microfusion

    Energy Technology Data Exchange (ETDEWEB)

    Sanmartin, J A; Barrero, A

    1976-07-01

    The quasi neutral, one dimensional motion generated in a cold, infinite, uniform plasma of density n{sub 0}, by the absorption, In a given plane, of a linear pulse of energy per unit time and area {phi} - {phi}{sub 0}t/{tau}, 0< t {<=} {tau}, is considered; the analysis allows for thermal conduction and viscosity of ions and electrons, their energy exchange, and an electron thermal flux limiter. The motion is found to be self similar and governed by single non dimensional parameter {alpha} similar{sub t}o(n{sup 2}{sub 0} {tau}/{phi}{sub 0}){sup 2}/3. Detailed asymptotic results are obtained for both {alpha}<<1and {alpha}>>1; the general (behaviour of the solution for arbitrary {alpha} is discussed. The analysis can be easily extended to the case of a plasma initially occupying a half-space, and throws light on the hydrodynamics of laser fusion plasmas. (Author) 51 refs.

  16. EDITORIAL: Interrelationship between plasma phenomena in the laboratory and in space

    Science.gov (United States)

    Koepke, Mark

    2008-07-01

    favor of theory-paper counterparts and, thus, the scientific support that laboratory results can provide to the development of space-relevant theoretical models is often under-recognized. It is unrealistic to expect the dimensional parameters corresponding to space plasma to be matchable in the laboratory. However, a laboratory experiment is considered well designed if the subset of parameters relevant to a specific process shares the same phenomenological regime as the subset of analogous space parameters, even if less important parameters are mismatched. Regime boundaries are assigned by normalizing a dimensional parameter to an appropriate reference or scale value to make it dimensionless and noting the values at which transitions occur in the physical behavior or approximations. An example of matching regimes for cold-plasma waves is finding a 45° diagonal line on the log--log CMA diagram along which lie both a laboratory-observed wave and a space-observed wave. In such a circumstance, a space plasma and a lab plasma will support the same kind of modes if the dimensionless parameters are scaled properly (Bellan 2006 Fundamentals of Plasma Physics (Cambridge: Cambridge University Press) p 227). The plasma source, configuration geometry, and boundary conditions associated with a specific laboratory experiment are characteristic elements that affect the plasma and plasma processes that are being investigated. Space plasma is not exempt from an analogous set of constraining factors that likewise influence the phenomena that occur. Typically, each morphologically distinct region of space has associated with it plasma that is unique by virtue of the various mechanisms responsible for the plasma's presence there, as if the plasma were produced by a unique source. Boundary effects that typically constrain the possible parameter values to lie within one or more restricted ranges are inescapable in laboratory plasma. The goal of a laboratory experiment is to examine the

  17. X-Ray photoelectron spectroscopy analysis of plasma-polymer interactions for development of low-damage plasma processing of soft materials

    International Nuclear Information System (INIS)

    Setsuhara, Yuichi; Cho, Ken; Shiratani, Masaharu; Sekine, Makoto; Hori, Masaru

    2010-01-01

    Plasma-polymer interactions have been investigated using atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS) of polyethyleneterephthalate (PET) films, which have been exposed to argon plasmas driven by low-inductance antenna modules as a parameter of ion energy. The AFM images indicated that the argon plasma exposure exhibited a significant change in surface roughness. The XPS analyses suggested that the degradation of chemical bonding structure and/or bond scission of PET could be effectively suppressed in the plasma exposures with ion energies below 6 eV. However, significant degradations of O = C-O bond, C-O bond and phenyl group were observed with increasing ion energy above 6 eV.

  18. Observations of solar flare transition zone plasmas from the Solar Maximum Mission

    Science.gov (United States)

    Cheng, C.-C.; Bruner, E. C.; Tandberg-Hanssen, E.; Woodgate, B. E.; Shine, R. A.; Kenny, P. J.; Henze, W.; Poletto, G.

    1982-01-01

    The spatial and temporal evolution of the Si IV and O IV intensity, density and mass motions in preflare and flare transition zone plasmas are studied for the case of the April 8, 1980 flare. It is found that: (1) the UV flare observed in the Si IV and O IV lines is unambiguously identified as occurring in a low-lying, preexisting transition zone loop which spanned the magnetic neutral line separating a larger leader spot and a newly emerged, isolated spot of opposite polarity; (2) at the onset of the flare, the easternmost footpoint, which was anchored in an isolated spot region of high longitudinal magnetic field gradient, showed sudden, impulsive brightening with large intensity increases; and (3) the release flare energy was transported by way of large-scale connecting field lines to other parts of the active region, producing the hot plasma and H-alpha kernels observed near the trailing spot.

  19. Hypervelocity dust particle impacts observed by the Giotto magnetometer and plasma experiments

    International Nuclear Information System (INIS)

    Neubauer, F.M.; Glassmeier, K.H.; Goldstein, R.; Acuna, M.H.; Musmann, G.; Coates, A.J.

    1990-01-01

    The authors report thirteen very short events in the magnetic field of the inner magnetic pile-up region of comet Halley observed by the Giotto magnetometer experiment together with simultaneous plasma data obtained by the Johnstone plasma analyzer and the ion mass spectrometer experiments. The events are due to dust impacts in the milligram range on the spacecraft at the relative velocity between the cometary dust and the spacecraft of 68 km/sec. They are generally consistent with dust impact events derived from spacecraft attitude perturbations by the Giotto camera [Curdt and Keller, private communication]. Their characteristic shape generally involves a sudden decrease in magnetic field magnitude, a subsequent overshoot beyond initial field values and an asymptotic approach to the initial field somewhat reminiscent of the magnetic field signature after the AMPTE releases in the solar wind. These observations give a new way of analyzing ultra-fast dust particles incident on a spacecraft

  20. Advantages of the first-derivative probe technique over the three- and four-parameter probe techniques in fusion plasmas diagnostics

    Czech Academy of Sciences Publication Activity Database

    Hasan, E.; Dimitrova, Miglena; Popov, T.; Ivanova, P.; Dejarnac, Renaud; Stöckel, Jan; Pánek, Radomír

    2018-01-01

    Roč. 13, č. 4 (2018), č. článku P04005. ISSN 1748-0221 R&D Projects: GA MŠk(CZ) LM2015045 Institutional support: RVO:61389021 Keywords : Plasma potential * electron temperature * bi-Maxwellian EEDF * Divertor Langmuir probes * three- and four-parameter probe techniques * first-derivative probe technique Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: 2.11 Other engineering and technologies Impact factor: 1.220, year: 2016 http://iopscience.iop.org/article/10.1088/1748-0221/13/04/P04005/meta

  1. Observation of finite-β MHD phenomena in Tokamaks

    International Nuclear Information System (INIS)

    McGuire, K.M.

    1985-01-01

    Stable high beta plasmas are required for the tokamak to attain an economical fusion reactor. Recently, intense neutral beam heating experiments in tokamaks have shown new effects on plasma stability and confinement associated with high beta plasmas. The observed spectrum of MHD fluctuations at high beta is clearly dominated by the n = 1 mode when the q = 1 surface is in the plasma. The m/n = 1/1 mode drives other n = 1 modes through toroidal coupling and n > 1 modes through nonlinear coupling. On PDX, with near perpendicular injection, a resonant interaction between the n = 1 internal kink and the trapped fast ions results in loss of beam particles and heating power. Key parameters in the theory are the value of qsub(o) and the injection angle. High frequency broadband magnetic fluctuations have been observed on ISX-B and D-III and a correlation with the deterioration of plasma confinement was reported. During enhanced confinement (H-mode) discharges in divertor plasmas two new edge instabilities were observed, both localized radially near the separatrix. By assembling results from the different tokamak experiments, it is found that the simple theoretical ideal MHD beta limit has not been exceeded

  2. Demeter high resolution observations of the ionospheric thermal plasma response to magnetospheric energy input during the magnetic storm of November 2004

    Directory of Open Access Journals (Sweden)

    E. Séran

    2008-01-01

    Full Text Available High resolution Demeter plasma and wave observations were available during one of the geomagnetic storms of November 2004 when the ionospheric footprint of the plasmasphere was pushed below 64 degrees in the midnight sector. We report here onboard observations of thermal/suprathermal plasma and HF electric field variations with a temporal resolution of 0.4 s, which corresponds to a spatial resolution of 3 km. Local perturbations of the plasma parameters at the altitude of 730 km are analysed with respect to the variation of the field-aligned currents, electron and proton precipitation and large-scale electric fields, measured in-situ by Demeter and by remote optical methods from the IMAGE/Polar satellites.

    Flow monitoring in the 21:00 and 24:00 MLT sectors during storm conditions reveals two distinct regions of O+ outflow, i.e. the region of the field-aligned currents, which often comprises few layers of opposite currents, and the region of velocity reversal toward dusk at sub-auroral latitudes. Average upward O+ velocities are identical in both local time sectors and vary between 200 and 450 m s−1, with an exception of a few cases of higher speed (~1000 m s−1 outflow, observed in the midnight sector. Each individual outflow event does not indicate any heating process of the thermal O+ population. On the contrary, the temperature of the O+, outflowing from auroral latitudes, is found to be even colder than that of the ambient ion plasma. The only ion population which is observed to be involved in the heating is the O+ with energies a few times higher than the thermal energy. Such a population was detected at sub-auroral latitudes in the region of duskward flow reversal. Its temperature raises up to a few eV inside the layer of sheared velocity.

    A deep decrease in the H+ density at heights and latitudes, where, according to the IRI model

  3. Probing a dusty magnetized plasma with self-excited dust-density waves

    Science.gov (United States)

    Tadsen, Benjamin; Greiner, Franko; Piel, Alexander

    2018-03-01

    A cloud of nanodust particles is created in a reactive argon-acetylene plasma. It is then transformed into a dusty magnetized argon plasma. Plasma parameters are obtained with the dust-density wave diagnostic introduced by Tadsen et al. [Phys. Plasmas 22, 113701 (2015), 10.1063/1.4934927]. A change from an open to a cylindrically enclosed nanodust cloud, which was observed earlier, can now be explained by a stronger electric confinement if a vertical magnetic field is present. Using two-dimensional extinction measurements and the inverse Abel transform to determine the dust density, a redistribution of the dust with increasing magnetic induction is found. The dust-density profile changes from being peaked around the central void to being peaked at an outer torus ring resulting in a hollow profile. As the plasma parameters cannot explain this behavior, we propose a rotation of the nanodust cloud in the magnetized plasma as the origin of the modified profile.

  4. Determination of parameters of the arc plasma of electrodynamic macro-particle accelerator by the method of simulation of surface energy losses

    Energy Technology Data Exchange (ETDEWEB)

    Djuric, Z.; Mihajlov, A.A. (Inst. of Physics, Belgrade (Yugoslavia))

    1989-01-01

    In the paper we have presented the model method of calculating electrical arc parameters in the macroparticles' electrodynamic accelerator at the given rail width and the given width between them. The method is based on energy losses simulation at the arc's boundary surfaces and is a modification of the one-dimensional version of Powell and Batteh's method. It has been shown that the proposed method is adequate for operative use and that it enables the determination of both macroscopic arc parameters - acceleration, length, electroconductivity, mean temperature and density of particles etc., as well as local arc plasma parameters. The values of these parameters are determined by numerical solutions of the self-consistent system of magnetic-hydrodynamic, material and thermodynamic equations, at the arc's given mass and muzzle voltage between rails. It has also been shown that the proposed method allows the comparison of one-, two- and three-dimensional arc approximations. In the present paper we have used the method assuming that arc plasma is at most doubly ionized and produced exclusively by copper atoms. (orig.).

  5. Pioneer 7 observations of plasma flow and field reversal regions in the distant geomagnetic tail

    International Nuclear Information System (INIS)

    Walker, R.C.; Villante, U.; Lazarus, A.J.

    1975-01-01

    We present the results of an extensive analysis of plasma and magnetic field data from Pioneer 7 taken in the geomagnetic tail approximately 1000 R/sub E/ downstream from earth. The principal observations are (1) measurable fluxes of protons in the tail, flowing away from earth, sometimes with a double-peaked velocity distribution; (2) field reversal regions in which the field changes from radial to antiradial by a vector rotation in the north-south plane; and (3) general characteristics of the tail similar to those observed near earth with good correlation between taillike magnetic fields and plasma

  6. Pioneer 7 observations of plasma flow and field reversal regions in the distant geomagnetic tail

    Science.gov (United States)

    Walker, R. C.; Lazarus, A. J.; Villante, U.

    1975-01-01

    The present paper gives the results of an extensive analysis of plasma and magnetic-field data from Pioneer 7 taken in the geomagnetic tail approximately 1000 earth radii downstream from earth. The principal observations are: (1) measurable fluxes of protons in the tail, flowing away from earth, sometimes with a double-peaked velocity distribution; (2) field reversal regions in which the field changes from radial to antiradial by a vector rotation in the north-south plane; and (3) general characteristics of the tail similar to those observed near earth with good correlation between taillike magnetic fields and plasma.

  7. Observation of plasma rotation driven by static nonaxisymmetric magnetic fields in a tokamak.

    Science.gov (United States)

    Garofalo, A M; Burrell, K H; DeBoo, J C; deGrassie, J S; Jackson, G L; Lanctot, M; Reimerdes, H; Schaffer, M J; Solomon, W M; Strait, E J

    2008-11-07

    We present the first evidence for the existence of a neoclassical toroidal rotation driven in a direction counter to the plasma current by nonaxisymmetric, nonresonant magnetic fields. At high beta and with large injected neutral beam momentum, the nonresonant field torque slows down the plasma toward the neoclassical "offset" rotation rate. With small injected neutral beam momentum, the toroidal rotation is accelerated toward the offset rotation, with resulting improvement in the global energy confinement time. The observed magnitude, direction, and radial profile of the offset rotation are consistent with neoclassical theory predictions.

  8. Effect of substrate and cathode parameters on the properties of suspension plasma sprayed solid oxide fuel cell electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Waldbillig, D.; Tang, Z.; Burgess, A. [British Columbia Univ., Vancouver, BC (Canada); Kesler, O. [Toronto Univ., ON (Canada)

    2008-07-01

    An axial injection suspension plasma spray system has been used to produce layers of fully stabilized yttriastabilized zirconia (YSZ) that could be used as solid oxide fuel cell (SOFC) electrolytes. Suspension plasma spraying is a promising technique for the rapid production of coatings with fine microstructures and controlled porosity without requiring a post-deposition heat treatment. This new manufacturing technique to produce SOFC active layers requires the build up of a number of different plasma sprayed SOFC functional layers (cathode, electrolyte and anode) sequentially on top of each other. To understand the influence of the substrate and previouslydeposited coating layers on subsequent coating layer properties, YSZ layers were deposited on top of plasma sprayed composite lanthanum strontium manganite (LSM)/YSZ cathode layers that were first deposited on porous ferritic stainless steel substrates. Three layer half cells consisting of the porous steel substrate, composite cathode, and suspension plasma sprayed electrolyte layer were then characterized. A systematic study was performed in order to investigate the effect of parameters such as substrate and cathode layer roughness, substrate surface pore size, and cathode microstructure and thickness on electrolyte deposition efficiency, cathode and electrolyte permeability, and layer microstructure. (orig.)

  9. Magnetosheath jets: MMS observations of internal structures and jet interactions with ambient plasma

    Science.gov (United States)

    Plaschke, F.; Karlsson, T.; Hietala, H.; Archer, M. O.; Voros, Z.; Nakamura, R.; Magnes, W.; Baumjohann, W.; Torbert, R. B.; Russell, C. T.; Giles, B. L.

    2017-12-01

    The dayside magnetosheath downstream of the quasi-parallel bow shock is commonly permeated by high-speed jets. Under low IMF cone angle conditions, large scale jets alone (with cross-sectional diameters of over 2 Earth radii) have been found to impact the subsolar magnetopause once every 6 minutes - smaller scale jets occurring much more frequently. The consequences of jet impacts on the magnetopause can be significant: they may trigger local reconnection and waves, alter radiation belt electron drift paths, disturb the geomagnetic field, and potentially generate diffuse throat aurora at the dayside ionosphere. Although some basic statistical properties of jets are well-established, their internal structure and interactions with the surrounding magnetosheath plasma are rather unknown. We present Magnetospheric Multiscale (MMS) observations which reveal a rich jet-internal structure of high-amplitude plasma moment and magnetic field variations and associated currents. These variations/structures are generally found to be in thermal and magnetic pressure balance; they mostly (but not always) convect with the plasma flow. Small velocity differences between plasma and structures are revealed via four-spacecraft timing analysis. Inside a jet core region, where the plasma velocity maximizes, structures are found to propagate forward (i.e., with the jet), whereas backward propagation is found outside that core region. Although super-magnetosonic flows are detected by MMS in the spacecraft frame of reference, no fast shock is seen as the jet plasma is sub-magnetosonic with respect to the ambient magnetosheath plasma. Instead, the fast jet plasma pushes ambient magnetosheath plasma ahead of the jet out of the way, possibly generating anomalous sunward flows in the vicinity, and modifies the magnetic field aligning it with the direction of jet propagation.

  10. Ulysses Radio Occultation Observations of the lo Plasma Torus During the Jupiter Encounter.

    Science.gov (United States)

    Bird, M K; Asmar, S W; Brenkle, J P; Edenhofer, P; Funke, O; Pätzold, M; Volland, H

    1992-09-11

    Radio signals from Ulysses were used to probe the lo plasma torus (IPT) shortly after the spacecraft's closest approach to Jupiter. The frequencies of the two downlinks at S-band (2.3 gigahertz) and X-band (8.4 gigahertz) were recorded, differenced, and integrated in order to derive the columnar electron density of the IPT. The measurements agree qualitatively with contemporary models of the IPT based on Voyager data, but significant differences are apparent as well. The overall level of the IPT electron density is approximately the same as the prediction, implying that the amount of gas (or plasma) injected from lo is similar to that observed during the Voyager era. On the other hand, the IPT seems to be less extended out of the centrifugal equator, implying a smaller plasma temperature than predicted.

  11. Therapeutic effects of marshmallow (Althaea officinalis L.) extract on plasma biochemical parameters of common carp infected with Aeromonas hydrophila.

    Science.gov (United States)

    Banaee, Mahdi; Soleimany, Vahid; Nematdoost Haghi, Behzad

    2017-01-01

    This study evaluated preclinical and clinical safety of marshmallow ( Althaea officinalis L.) extract as a naturopathic medicine in common carp deliberately infected with Aeromonas hydrophila . The fish were fed 0 (control), 2.50, 5.00 and 10.00 g of marshmallow extract for 60 days in a preclinical experiment and then, challenged with A. hydrophila for a 10-day experiment. Significant increases were observed in aspartate aminotransferase (AST), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), creatine phosphokinase (CPK) activities and plasma creatinine levels in fish fed 10 g marshmallow extract per kg feed. However, alanine aminotransferase (ALT) significantly decreased on day 60. The fish fed 2.50 g marshmallow extract per kg feed indicated increased levels of total protein and globulin. There were no significant changes in albumin levels ( p > 0.05). 2.50 and 5.00 g marshmallow significantly decreased triglyceride and cholesterol levels and increased glucose levels ( p Marshmallow extract at 5.00 and 10.00 g can adjust plasma biochemical parameters in fish challenged with A. hydrophila . The results of preclinical studies and pharmaceutical toxicity of marshmallow extract revealed that dietary levels lower than 5.00 g were safe and effective. The results of this clinical study demonstrated that marshmallow extract (5.00 g kg -1 feed) can protect fish against A. hydrophila .

  12. THE POWER OF IMAGING: CONSTRAINING THE PLASMA PROPERTIES OF GRMHD SIMULATIONS USING EHT OBSERVATIONS OF Sgr A*

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Chi-Kwan; Psaltis, Dimitrios; Özel, Feryal [Steward Observatory and Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Narayan, Ramesh [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Sadowski, Aleksander, E-mail: chanc@email.arizona.edu [MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)

    2015-01-20

    Recent advances in general relativistic magnetohydrodynamic simulations have expanded and improved our understanding of the dynamics of black-hole accretion disks. However, current simulations do not capture the thermodynamics of electrons in the low density accreting plasma. This poses a significant challenge in predicting accretion flow images and spectra from first principles. Because of this, simplified emission models have often been used, with widely different configurations (e.g., disk- versus jet-dominated emission), and were able to account for the observed spectral properties of accreting black holes. Exploring the large parameter space introduced by such models, however, requires significant computational power that exceeds conventional computational facilities. In this paper, we use GRay, a fast graphics processing unit (GPU) based ray-tracing algorithm, on the GPU cluster El Gato, to compute images and spectra for a set of six general relativistic magnetohydrodynamic simulations with different magnetic field configurations and black-hole spins. We also employ two different parametric models for the plasma thermodynamics in each of the simulations. We show that, if only the spectral properties of Sgr A* are used, all 12 models tested here can fit the spectra equally well. However, when combined with the measurement of the image size of the emission using the Event Horizon Telescope, current observations rule out all models with strong funnel emission, because the funnels are typically very extended. Our study shows that images of accretion flows with horizon-scale resolution offer a powerful tool in understanding accretion flows around black holes and their thermodynamic properties.

  13. Plasma heating by non-linear wave-Plasma interaction | Echi ...

    African Journals Online (AJOL)

    We simulate the non-linear interaction of waves with magnetized tritium plasma with the aim of determining the parameter values that characterize the response of the plasma. The wave-plasma interaction has a non-conservative Hamiltonian description. The resulting system of Hamilton's equations is integrated numerically ...

  14. Studies of plasma interactions with tungsten targets in PF-1000U facility

    Directory of Open Access Journals (Sweden)

    Ladygina Maryna S.

    2016-06-01

    Full Text Available This paper presents results of experimental studies of tungsten samples of 99.95% purity, which were irradiated by intense plasma-ion streams. The behaviour of tungsten, and particularly its structural change induced by high plasma loads, is of great importance for fusion technology. The reported measurements were performed within a modified PF-1000U plasma-focus facility operated at the IFPiLM in Warsaw, Poland. The working gas was pure deuterium. In order to determine the main plasma parameters and to study the behaviour of impurities at different instants of the plasma discharge, the optical emission spectroscopy was used. The dependence of plasma parameters on the initial charging voltage (16, 19 and 21 kV was studied. Detailed optical measurements were performed during interactions of a plasma stream with the tungsten samples placed at the z-axis of the facility, at a distance of 6 cm from the electrode outlets. The recorded spectra showed distinct WI and WII spectral lines. Investigation of a target surface morphology, after its irradiation by intense plasma streams, was performed by means of an optical microscope. The observations revealed that some amounts of the electrodes material (mainly copper were deposited upon the irradiated sample surface. In all the cases, melted zones were observed upon the irradiated target surface, and in experiments performed at the highest charging voltage there were formed some cracks.

  15. Collisionless scattering of plasma cloud in a dipole magnetic field

    International Nuclear Information System (INIS)

    Osipyan, D.A.

    2006-01-01

    Results of numerical simulation of dense plasma cloud scattering dynamics in a magnetized background and MHD indignations generation are presented. The magnetic field has dipole structure. The initial system of equations includes the Vlasov equations for ionic components of plasma, hydrodynamic approach for electrons and Maxwell's system of equations. The method of solution is based on the use of the method of particles in cells and finite difference splitting schemes. Quantitative characteristics of dependence of scattering cloud parameters from the Mach-Alfven number and parameter of magnetic laminar interaction are observed. In particular, a condition of more effective deformation of a cloud is large values of the Mach-Alfven numbers and small parameters of the magnetic laminar interaction

  16. Deviations from thermal equilibrium in plasmas

    International Nuclear Information System (INIS)

    Burm, K.T.A.L.

    2004-01-01

    A plasma system in local thermal equilibrium can usually be described with only two parameters. To describe deviations from equilibrium two extra parameters are needed. However, it will be shown that deviations from temperature equilibrium and deviations from Saha equilibrium depend on one another. As a result, non-equilibrium plasmas can be described with three parameters. This reduction in parameter space will ease the plasma describing effort enormously

  17. A statistical survey of heat input parameters into the cusp thermosphere

    Science.gov (United States)

    Moen, J. I.; Skjaeveland, A.; Carlson, H. C.

    2017-12-01

    Based on three winters of observational data, we present those ionosphere parameters deemed most critical to realistic space weather ionosphere and thermosphere representation and prediction, in regions impacted by variability in the cusp. The CHAMP spacecraft revealed large variability in cusp thermosphere densities, measuring frequent satellite drag enhancements, up to doublings. The community recognizes a clear need for more realistic representation of plasma flows and electron densities near the cusp. Existing average-value models produce order of magnitude errors in these parameters, resulting in large under estimations of predicted drag. We fill this knowledge gap with statistics-based specification of these key parameters over their range of observed values. The EISCAT Svalbard Radar (ESR) tracks plasma flow Vi , electron density Ne, and electron, ion temperatures Te, Ti , with consecutive 2-3 minute windshield-wipe scans of 1000x500 km areas. This allows mapping the maximum Ti of a large area within or near the cusp with high temporal resolution. In magnetic field-aligned mode the radar can measure high-resolution profiles of these plasma parameters. By deriving statistics for Ne and Ti , we enable derivation of thermosphere heating deposition under background and frictional-drag-dominated magnetic reconnection conditions. We separate our Ne and Ti profiles into quiescent and enhanced states, which are not closely correlated due to the spatial structure of the reconnection foot point. Use of our data-based parameter inputs can make order of magnitude corrections to input data driving thermosphere models, enabling removal of previous two fold drag errors.

  18. Localized fast flow disturbance observed in the plasma sheet and in the ionosphere

    Directory of Open Access Journals (Sweden)

    R. Nakamura

    2005-02-01

    Full Text Available An isolated plasma sheet flow burst took place at 22:02 UT, 1 September 2002, when the Cluster footpoint was located within the area covered by the Magnetometers-Ionospheric Radars-All-sky Cameras Large Experiment (MIRACLE. The event was associated with a clear but weak ionospheric disturbance and took place during a steady southward IMF interval, about 1h preceding a major substorm onset. Multipoint observations, both in space and from the ground, allow us to discuss the temporal and spatial scale of the disturbance both in the magnetosphere and ionosphere. Based on measurements from four Cluster spacecraft it is inferred that Cluster observed the dusk side part of a localized flow channel in the plasma sheet with a flow shear at the front, suggesting a field-aligned current out from the ionosphere. In the ionosphere the equivalent current pattern and possible field-aligned current location show a pattern similar to the auroral streamers previously obtained during an active period, except for its spatial scale and amplitude. It is inferred that the footpoint of Cluster was located in the region of an upward field-aligned current, consistent with the magnetospheric observations. The entire disturbance in the ionosphere lasted about 10min, consistent with the time scale of the current sheet disturbance in the magnetosphere. The plasma sheet bulk flow, on the other hand, had a time scale of about 2min, corresponding to the time scale of an equatorward excursion of the enhanced electrojet. These observations confirm that localized enhanced convection in the magnetosphere and associated changes in the current sheet structure produce a signature with consistent temporal and spatial scale at the conjugate ionosphere.

  19. Studies of electron cyclotron resonance ion source plasma physics

    International Nuclear Information System (INIS)

    Tarvainen, O.

    2005-01-01

    This thesis consists of an introduction to the plasma physics of electron cyclotron resonance ion sources (ECRIS) and a review of the results obtained by the author and co-workers including discussion of related work by others. The thesis begins with a theoretical discussion dealing with plasma physics relevant for the production of highly charged ions in ECR ion source plasmas. This is followed by an overview of different techniques, such as gas mixing and double frequency heating, that can be used to improve the performance of this type of ion source. The experimental part of the work consists of studies related to ECRIS plasma physics. The effect of the gas mixing technique on the production efficiency of different ion beams was studied with both gaseous and solid materials. It was observed that gas mixing improves the confinement of the heavier element while the confinement of the lighter element is reduced. When the effect of gas mixing on MIVOC-plasmas was studied with several mixing gases it was observed that applying this technique can reduce the inevitable carbon contamination by a significant factor. In order to understand the different plasma processes taking place in ECRIS plasmas, a series of plasma potential and emittance measurements was carried out. An instrument, which can be used to measure the plasma potential in a single measurement without disturbing the plasma, was developed for this work. Studying the plasma potential of ECR ion sources is important not only because it helps to understand different plasma processes, but also because the information can be used as an input parameter for beam transport simulations and ion source extraction design. The experiments performed have revealed clear dependencies of the plasma potential on certain source parameters such as the amount of carbon contamination accumulated on the walls of the plasma chamber during a MIVOC-run. It was also observed that gas mixing affects not only the production efficiency

  20. Observation at the planet Mercury by the plasma electron experiment: Mariner Mariner 10

    International Nuclear Information System (INIS)

    Ogilvie, K.W.; Scudder, J.D.; Vasyliunas, V.M.; Hartle, R.E.; Siscoe, G.L.

    1977-01-01

    Plasma electron observations made on board Mariner 10 during its three encounters with the planet Mercury show that the planet interacts with the solar wind to form a bow shock and a permanent magnetosphere. The observations provide a determination of the dimensions and properties of the magnetosphere, independently of and in general agreement with magnetometer observations. The magnetosphere of Mercury appears to be similar in shape to that of the earth but much smaller in relation to the size of the planet. The average distance from the center of Mercury to the subsolar point of the magnetopause is approx.1.4 planetary radii. Electron populations similar to those found in the earth's magneto-tail, within the plasma sheet and adjacent regions, were observed at Mercury; both their spatial location and the electron energy spectra within them bear qualitative and quantitative resemblance to corresponding observations at the earth. In general, the magnetosphere of Mercury resembles to a marked degree a reduced version of that of the earth, there being no significant differences of structure revealed by the Mariner 10 observations. Quantities in the two magnetospheres are related by simple scaling laws. The size of Mercury relative to its magnetosphere precludes, however, the existence of stably trapped particle belts and of inner magnetosphere (Lapproximately-less-than8 at the earth) phenomena generally

  1. Traveling magnetopause distortion related to a large-scale magnetosheath plasma jet: THEMIS and ground-based observations

    Science.gov (United States)

    Dmitriev, A. V.; Suvorova, A. V.

    2012-08-01

    Here, we present a case study of THEMIS and ground-based observations of the perturbed dayside magnetopause and the geomagnetic field in relation to the interaction of an interplanetary directional discontinuity (DD) with the magnetosphere on 16 June 2007. The interaction resulted in a large-scale local magnetopause distortion of an "expansion - compression - expansion" (ECE) sequence that lasted for ˜15 min. The compression was caused by a very dense, cold, and fast high-βmagnetosheath plasma flow, a so-called plasma jet, whose kinetic energy was approximately three times higher than the energy of the incident solar wind. The plasma jet resulted in the effective penetration of magnetosheath plasma inside the magnetosphere. A strong distortion of the Chapman-Ferraro current in the ECE sequence generated a tripolar magnetic pulse "decrease - peak- decrease" (DPD) that was observed at low and middle latitudes by some ground-based magnetometers of the INTERMAGNET network. The characteristics of the ECE sequence and the spatial-temporal dynamics of the DPD pulse were found to be very different from any reported patterns of DD interactions with the magnetosphere. The observed features only partially resembled structures such as FTE, hot flow anomalies, and transient density events. Thus, it is difficult to explain them in the context of existing models.

  2. V-I curves and plasma parameters in a high density DC glow discharge generated by a current-source

    International Nuclear Information System (INIS)

    Granda-Gutierrez, E E; Lopez-Callejas, R; Piedad-Beneitez, A de la; BenItez-Read, J S; Pacheco-Sotelo, J O; Pena-Eguiluz, R; A, R Valencia; Mercado-Cabrera, A; Barocio, S R

    2008-01-01

    Nitrogen DC glow discharges, conducted in a cylindrical geometry, have been characterized using a new current-source able to provide 10 -3 - 3 A for the sustainment of the discharge, instead of a conventional voltage-source. The V-I characteristic curves obtained from these discharges were found to fit the general form i(v) = A(p)v k(p) , whereby the plasma itself can be modeled as a voltage-controlled current-source. We conclude that the fitting parameters A and k, which mainly depend on the gas pressure p, are strongly related to the plasma characteristics, so much so that they can indicate the pressure interval in which the maximum plasma density is located, with values in the order of 10 16 m -3 at reduced discharge potential (300-600 V) and low working pressure (10 -1 - 10 1 Pa)

  3. ℋ- adaptive observer design and parameter identification for a class of nonlinear fractional-order systems

    KAUST Repository

    Ndoye, Ibrahima; Voos, Holger; Laleg-Kirati, Taous-Meriem; Darouach, Mohamed

    2014-01-01

    In this paper, an adaptive observer design with parameter identification for a nonlinear system with external perturbations and unknown parameters is proposed. The states of the nonlinear system are estimated by a nonlinear observer and the unknown

  4. Observations of multiple order parameters in 5f electron systems

    International Nuclear Information System (INIS)

    Blackburn, E.

    2005-12-01

    In this thesis, multiple order parameters originating in the same electronic system are studied. The multi-k magnetic structures, where more than one propagation wavevector, k, is observed in the same volume, are considered as prototypical models. The effect of this structure on the elastic and inelastic response is studied. In cubic 3-k uranium rock-salts, unexpected elastic diffraction events were observed at positions in reciprocal space where the structure factor should have been zero. These diffraction peaks are identified with correlations between the (orthogonal) magnetic order parameters. The 3-k structure also affects the observed dynamics; the spin-wave fluctuations in uranium dioxide as observed by inelastic neutron polarization analysis can only be explained on the basis of a 3-k structure. In the antiferromagnetic superconductor UPd 2 Al 3 the magnetic order and the super-conducting state coexist, and are apparently generated by the same heavy fermions. The effect of an external magnetic field on both the normal and superconducting states is examined. In the normal state, the compound displays Fermi-liquid-like behaviour. The inelastic neutron response is strongly renormalized on entering the superconducting state, and high-precision measurements of the low-energy transfer part of this response confirm that the superconducting energy gap has the same symmetry as the antiferromagnetic lattice. (author)

  5. Opacity measurements in shock-generated argon plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Erskine, D.

    1993-07-01

    Dense plasmas having uniform and constant density and temperature are generated by passage of a planar shock wave through gas. The opacity of the plasma is accurately measured versus wavelength by recording the risetime of emitted light. This technique is applicable to a wide variety of species and plasma conditions. Initial experiments in argon have produced plasmas with 2 eV temperatures, 0.004--0.04 g/cm{sup 3} densities, and coupling parameters {Gamma} {approximately}0.3--0.7. Measurements in visible light are compared with calculations using the HOPE code. An interesting peak in the capacity at 400 nm is observed for the first time and is identified with the 4s-5p transition in excited neutral argon atoms.

  6. Self-organization observed in either fusion or strongly coupled plasmas

    International Nuclear Information System (INIS)

    Himura, Haruhiko; Sanpei, Akio

    2011-01-01

    If self-organization happens in the fusion plasma, the plasma alters its shape by weakening the confining magnetic field. The self-organized plasma is stable and robust, so its configuration is conserved even during transport in asymmetric magnetic fields. The self-organization of the plasma is driven by an electrostatic potential. Examples of the plasma that has such strong potential are non-neutral plasmas of pure ions or electrons and dusty plasmas. In the present paper, characteristic phenomena of strongly coupled plasmas such as particle aggregation and formation of the ordered structure are discussed. (T.I.)

  7. Observations of core toroidal rotation reversals in Alcator C-Mod ohmic L-mode plasmas

    International Nuclear Information System (INIS)

    Rice, J.E.; Reinke, M.L.; Podpaly, Y.A.; Churchill, R.M.; Cziegler, I.; Dominguez, A.; Ennever, P.C.; Fiore, C.L.; Granetz, R.S.; Greenwald, M.J.; Hubbard, A.E.; Hughes, J.W.; Irby, J.H.; Ma, Y.; Marmar, E.S.; McDermott, R.M.; Porkolab, M.; Duval, B.P.; Bortolon, A.; Diamond, P.H.

    2011-01-01

    Direction reversals of intrinsic toroidal rotation have been observed in Alcator C-Mod ohmic L-mode plasmas following modest electron density or toroidal magnetic field ramps. The reversal process occurs in the plasma interior, inside of the q = 3/2 surface. For low density plasmas, the rotation is in the co-current direction, and can reverse to the counter-current direction following an increase in the electron density above a certain threshold. Reversals from the co- to counter-current direction are correlated with a sharp decrease in density fluctuations with k R ≥ 2 cm -1 and with frequencies above 70 kHz. The density at which the rotation reverses increases linearly with plasma current, and decreases with increasing magnetic field. There is a strong correlation between the reversal density and the density at which the global ohmic L-mode energy confinement changes from the linear to the saturated regime.

  8. Profiles of plasma parameters and density of negative hydrogen ions by laser detachment measurements in RF-driven ion sources

    International Nuclear Information System (INIS)

    Christ-Koch, Sina

    2007-01-01

    This work shows the application of the Laserdetachment method for spatially resolved measurements of negative Hydrogen/Deuterium ion density. It was applied on a high power low pressure RF-driven ion source. The Laser detachment method is based on the measurement of electron currents on a positively biased Langmuir probe before and during/after a laser pulse. The density ratio of negative ions to electrons can be derived from the ratio of currents to the probe. The absolute density of negative ions can be obtained when the electron density is measured with the standard Langmuir probe setup. Measurements with the Langmuir probe additionally yield information about the floating and plasma potential, the electron temperature and the density of positive ions. The Laser detachment setup had to be adapted to the special conditions of the RF-driven source. In particular the existence of RF fields (1 MHz), high source potential (-20 kV), magnetic fields (∝ 7 mT) and caesium inside the source had to be considered. The density of negative ions could be identified in the range of n(H - )=1.10 17 1/m 3 , which is in the same order of magnitude as the electron density. Only the application of the Laser detachment method with the Langmuir probe measurements will yield spatially resolved plasma parameters and H- density profiles. The influence of diverse external parameters, such as pressure, RF-power, magnetic fields on the plasma parameters and their profiles were studied and explained. Hence, the measurements lead to a detailed understanding of the processes inside the source. (orig.)

  9. Structural observability analysis and EKF based parameter estimation of building heating models

    Directory of Open Access Journals (Sweden)

    D.W.U. Perera

    2016-07-01

    Full Text Available Research for enhanced energy-efficient buildings has been given much recognition in the recent years owing to their high energy consumptions. Increasing energy needs can be precisely controlled by practicing advanced controllers for building Heating, Ventilation, and Air-Conditioning (HVAC systems. Advanced controllers require a mathematical building heating model to operate, and these models need to be accurate and computationally efficient. One main concern associated with such models is the accurate estimation of the unknown model parameters. This paper presents the feasibility of implementing a simplified building heating model and the computation of physical parameters using an off-line approach. Structural observability analysis is conducted using graph-theoretic techniques to analyze the observability of the developed system model. Then Extended Kalman Filter (EKF algorithm is utilized for parameter estimates using the real measurements of a single-zone building. The simulation-based results confirm that even with a simple model, the EKF follows the state variables accurately. The predicted parameters vary depending on the inputs and disturbances.

  10. Sandwich structure of plasma edge during transition to improved confinement regime in L-2M stellarator

    International Nuclear Information System (INIS)

    Shchepetov, S V; Kholnov, Yu V; Fedyanin, O I; Kuznetsov, A B; Vasilkov, D G; Akulina, D K; Batanov, G M; Gladkov, G A; Grebenshchikov, S E; Meshcheryakov, A I

    2008-01-01

    Transitions to the regime with better confinement in the L-2M stellarator are presented. Transitions are indicated only at sufficiently high plasma densities, and for a given value of average density they appear only at higher heating powers. Each transition is easily identified by a sudden fast ( e ). In the bulk of the plasma parameters evolve slowly. Drastic changes are observed in the region close to the plasma boundary where two moderate order rational magnetic surfaces are located with the rotational transform μ taking the values 2/3 and 3/4. Relative values of plasma parameters' fluctuations and their spectrum widths decrease significantly in this region. The region has a definite sandwich structure being subdivided by the above-named moderate order rational magnetic surfaces into three smaller zones with different plasma parameter dynamics. Transition is triggered by local disturbances of plasma parameters that are caused by instabilities in the vicinity of magnetic surfaces where μ is equal to 2/3 or 3/4. Different hypotheses on the nature of the phenomenon are discussed

  11. 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

  12. Association of Seminal Plasma Total Antioxidant Capacity and Malondialdehyde Levels With Sperm Parameters in Infertile Men With Varicocele

    Directory of Open Access Journals (Sweden)

    Salimi

    2016-05-01

    Full Text Available Background Varicocele is one of the most common reasons for male infertility and could impair spermatogenesis through mechanisms that are not well known. Recently, oxidative stress has been introduced as a major reason for male infertility caused by varicocele. Objectives In the current study, we aimed to assess the TAC (total antioxidant capacity and MDA (malondialdehyde as stress oxidative markers in infertile men with varicocele and fertile men, and moreover, their correlation with sperm parameters. Patients and Methods This case control study was performed on 43 infertile men with varicocele and 46 men with proven fertility. The ferric reducing ability of plasma (FRAP and thiobarbituric acid (TBA reaction methods were used for seminal plasma TAC and MDA assay, respectively. Results Lower TAC levels (1.7 ± 0.2 vs. 1.3 ± 0.4 mmol/L, P = 0.0004 and higher MDA levels (2.5 ± 1.1 vs. 5.8 ± 1.9 mmol/L, P < 0.0001 were observed in infertile men with varicocele compared to fertile men. There was no correlation between TAC and MDA in fertile men (r = 0.02, P = 0.9, however, a negative correlation was found between TAC and MDA levels in varicocele infertile men (r = −0.44, P = 0.003. Moreover, a positive correlation was found between sperm count and sperm motility with TAC levels in varicocele infertile men (r = 0.4, P = 0.02 and r = 0.6, P < 0.0001, respectively. There was a correlation between sperm motility and TAC levels in fertile men (r = 0.5, P = 0.001, but other parameters did not correlate with TAC in this group. A negative correlation was shown between semen volume, sperm count, total sperm, sperm motility, and sperm morphology with MDA levels in varicocele infertile men (r = 0.3, P = 0.045; r = −0.4, P = 0.009; r = −0.5, P = 0.002; r = −0.5, P = 0.001 and r = −0.4, P = 0.008, respectively. There was no correlation between these parameters and MDA in fertile men. Conclusions Our findings indicated that oxidative stress could

  13. A variable-coefficient unstable nonlinear Schroedinger model for the electron beam plasmas and Rayleigh-Taylor instability in nonuniform plasmas: Solutions and observable effects

    International Nuclear Information System (INIS)

    Gao Yitian; Tian Bo

    2003-01-01

    A variable-coefficient unstable nonlinear Schroedinger model is hereby investigated, which arises in such applications as the electron-beam plasma waves and Rayleigh-Taylor instability in nonuniform plasmas. With computerized symbolic computation, families of exact analytic dark- and bright-soliton-like solutions are found, of which some previously published solutions turn out to be the special cases. Similarity solutions also come out, which are expressible in terms of the elliptic functions and the second Painleve transcendent. Some observable effects caused by the variable coefficient are predicted, which may be detected in the future with the relevant space or laboratory plasma experiments with nonuniform background existing

  14. Laboratory simulation of space plasma phenomena*

    Science.gov (United States)

    Amatucci, B.; Tejero, E. M.; Ganguli, G.; Blackwell, D.; Enloe, C. L.; Gillman, E.; Walker, D.; Gatling, G.

    2017-12-01

    Laboratory devices, such as the Naval Research Laboratory's Space Physics Simulation Chamber, are large-scale experiments dedicated to the creation of large-volume plasmas with parameters realistically scaled to those found in various regions of the near-Earth space plasma environment. Such devices make valuable contributions to the understanding of space plasmas by investigating phenomena under carefully controlled, reproducible conditions, allowing for the validation of theoretical models being applied to space data. By working in collaboration with in situ experimentalists to create realistic conditions scaled to those found during the observations of interest, the microphysics responsible for the observed events can be investigated in detail not possible in space. To date, numerous investigations of phenomena such as plasma waves, wave-particle interactions, and particle energization have been successfully performed in the laboratory. In addition to investigations such as plasma wave and instability studies, the laboratory devices can also make valuable contributions to the development and testing of space plasma diagnostics. One example is the plasma impedance probe developed at NRL. Originally developed as a laboratory diagnostic, the sensor has now been flown on a sounding rocket, is included on a CubeSat experiment, and will be included on the DoD Space Test Program's STP-H6 experiment on the International Space Station. In this presentation, we will describe several examples of the laboratory investigation of space plasma waves and instabilities and diagnostic development. *This work supported by the NRL Base Program.

  15. The Role of Spraying Parameters and Inert Gas Shrouding in Hybrid Water-Argon Plasma Spraying of Tungsten and Copper for Nuclear Fusion Applications

    Czech Academy of Sciences Publication Activity Database

    Matějíček, Jiří; Kavka, Tetyana; Bertolissi, Gabriele; Ctibor, Pavel; Vilémová, Monika; Mušálek, Radek; Nevrlá, Barbara

    2013-01-01

    Roč. 22, č. 5 (2013), s. 744-755 ISSN 1059-9630 R&D Projects: GA MPO FR-TI2/702; GA TA ČR TA01010300 Institutional support: RVO:61389021 Keywords : plasma spraying * tungsten * copper * inert gas shrouding * water-argon plasma torch * gas shroud * hybrid plasma torch * influence of spray parameters * nuclear fusion * oxidation Subject RIV: JG - Metallurgy Impact factor: 1.491, year: 2013 http://link.springer.com/content/pdf/10.1007%2Fs11666-013-9895-x.pdf

  16. 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.

  17. The concept of temperature in space plasmas

    Science.gov (United States)

    Livadiotis, G.

    2017-12-01

    Independently of the initial distribution function, once the system is thermalized, its particles are stabilized into a specific distribution function parametrized by a temperature. Classical particle systems in thermal equilibrium have their phase-space distribution stabilized into a Maxwell-Boltzmann function. In contrast, space plasmas are particle systems frequently described by stationary states out of thermal equilibrium, namely, their distribution is stabilized into a function that is typically described by kappa distributions. The temperature is well-defined for systems at thermal equilibrium or stationary states described by kappa distributions. This is based on the equivalence of the two fundamental definitions of temperature, that is (i) the kinetic definition of Maxwell (1866) and (ii) the thermodynamic definition of Clausius (1862). This equivalence holds either for Maxwellians or kappa distributions, leading also to the equipartition theorem. The temperature and kappa index (together with density) are globally independent parameters characterizing the kappa distribution. While there is no equation of state or any universal relation connecting these parameters, various local relations may exist along the streamlines of space plasmas. Observations revealed several types of such local relations among plasma thermal parameters.

  18. Design of a helicon plasma source for ion–ion plasma production

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, N., E-mail: narayan.sharma@cppipr.res.in; Chakraborty, M.; Neog, N.K.; Bandyopadhyay, M.

    2017-04-15

    Highlights: • Development of a helicon plasma system to carry out ion–ion plasma studies in electronegative gases such as Hydrogen, Oxygen and Chlorine. • Determination of initial parameters of helicon plasma source for ion–ion plasma by using dispersion relation of bounded helicon waves. • Design and development of solenoid with magnetic field strength production capability of ∼ 600 G along the axis of the chamber. • Optimization of the chamber parameters using Helic codes and estimation of optimum attainable density. • Estimation of RF power requirements for various gases. - Abstract: A helicon plasma system is being designed and developed at CPP-IPR. The design parameters of the system are deduced from the dispersion relation of bounded helicon waves and the required magnetic fields are simulated by using Poisson Superfish code. The Helic code is used to simulate the power deposition profile for various conditions and to investigate the optimum values of chamber parameters for effective coupling of radio frequency (RF) power to plasma. The helicon source system is aimed at carrying out ion–ion plasma studies in electronegative gases such as Hydrogen, Oxygen and Chlorine. The system mainly consists of a source chamber in which helicon plasma will be produced by injecting RF power at a frequency of 13.56 MHz through a right helical antenna in presence of a DC magnetic field followed by an expansion chamber in which it is expected to produce negative ions along with the positive ions. Installation of the various parts of the system is in progress. The details of the design and development of the system is presented in this article.

  19. Plasma heating due to X-B mode conversion in a cylindrical ECR plasma system

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, V.K.; Bora, D. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat (India)

    2004-07-01

    Extra Ordinary (X) mode conversion to Bernstein wave near Upper Hybrid Resonance (UHR) layer plays an important role in plasma heating through cyclotron resonance. Wave generation at UHR and parametric decay at high power has been observed during Electron Cyclotron Resonance (ECR) heating experiments in toroidal magnetic fusion devices. A small linear system with ECR and UHR layer within the system has been used to conduct experiments on X-B conversion and parametric decay process as a function of system parameters. Direct probing in situ is conducted and plasma heating is evidenced by soft x-ray emission measurement. Experiments are performed with hydrogen plasma produced with 160-800 W microwave power at 2.45 GHz of operating frequency at 10{sup -3} mbar pressure. The axial magnetic field required for ECR is such that the resonant surface (B = 875 G) is situated at the geometrical axis of the plasma system. Experimental results will be presented in the paper. (authors)

  20. Adaptive distributed parameter and input estimation in linear parabolic PDEs

    KAUST Repository

    Mechhoud, Sarra

    2016-01-01

    First, new sufficient identifiability conditions of the input and the parameter simultaneous estimation are stated. Then, by means of Lyapunov-based design, an adaptive estimator is derived in the infinite-dimensional framework. It consists of a state observer and gradient-based parameter and input adaptation laws. The parameter convergence depends on the plant signal richness assumption, whereas the state convergence is established using a Lyapunov approach. The results of the paper are illustrated by simulation on tokamak plasma heat transport model using simulated data.

  1. On plasma ion beam formation in the Advanced Plasma Source

    International Nuclear Information System (INIS)

    Harhausen, J; Foest, R; Hannemann, M; Ohl, A; Brinkmann, R P; Schröder, B

    2012-01-01

    The Advanced Plasma Source (APS) is employed for plasma ion-assisted deposition (PIAD) of optical coatings. The APS is a hot cathode dc glow discharge which emits a plasma ion beam to the deposition chamber at high vacuum (p ≲ 2 × 10 −4 mbar). It is established as an industrial tool but to date no detailed information is available on plasma parameters in the process chamber. As a consequence, the details of the generation of the plasma ion beam and the reasons for variations of the properties of the deposited films are barely understood. In this paper the results obtained from Langmuir probe and retarding field energy analyzer diagnostics operated in the plasma plume of the APS are presented, where the source was operated with argon. With increasing distance to the source exit the electron density (n e ) is found to drop by two orders of magnitude and the effective electron temperature (T e,eff ) drops by a factor of five. The parameters close to the source region read n e ≳ 10 11 cm −3 and T e,eff ≳ 10 eV. The electron distribution function exhibits a concave shape and can be described in the framework of the non-local approximation. It is revealed that an energetic ion population leaves the source region and a cold ion population in the plume is build up by charge exchange collisions with the background neutral gas. Based on the experimental data a scaling law for ion beam power is deduced, which links the control parameters of the source to the plasma parameters in the process chamber. (paper)

  2. Testing backreaction effects with observational Hubble parameter data

    Science.gov (United States)

    Cao, Shu-Lei; Teng, Huan-Yu; Wan, Hao-Yi; Yu, Hao-Ran; Zhang, Tong-Jie

    2018-02-01

    The spatially averaged inhomogeneous Universe includes a kinematical backreaction term Q_{D} that is relate to the averaged spatial Ricci scalar _{D} in the framework of general relativity. Under the assumption that Q_{D} and _{D} obey the scaling laws of the volume scale factor a_{D}, a direct coupling between them with a scaling index n is remarkable. In order to explore the generic properties of a backreaction model for explaining the accelerated expansion of the Universe, we exploit two metrics to describe the late time Universe. Since the standard FLRW metric cannot precisely describe the late time Universe on small scales, the template metric with an evolving curvature parameter κ _{D}(t) is employed. However, we doubt the validity of the prescription for κ _{D}, which motivates us apply observational Hubble parameter data (OHD) to constrain parameters in dust cosmology. First, for FLRW metric, by getting best-fit constraints of Ω^{D_0}_m = 0.25^{+0.03}_{-0.03}, n = 0.02^{+0.69}_{-0.66}, and H_{D_0} = 70.54^{+4.24}_{-3.97} km s^{-1 Mpc^{-1}}, the evolutions of parameters are explored. Second, in template metric context, by marginalizing over H_{D_0} as a prior of uniform distribution, we obtain the best-fit values of n=-1.22^{+0.68}_{-0.41} and Ωm^{D0}=0.12^{+0.04}_{-0.02}. Moreover, we utilize three different Gaussian priors of H_{D_0}, which result in different best-fits of n, but almost the same best-fit value of Ωm^{D0}˜ 0.12. Also, the absolute constraints without marginalization of parameter are obtained: n=-1.1^{+0.58}_{-0.50} and Ωm^{D0}=0.13± 0.03. With these constraints, the evolutions of the effective deceleration parameter q^{D} indicate that the backreaction can account for the accelerated expansion of the Universe without involving extra dark energy component in the scaling solution context. Nevertheless, the results also verify that the prescription of κ _{D} is insufficient and should be improved.

  3. Measuring the Plasma Density of a Ferroelectric Plasma Source in an Expanding Plasma

    International Nuclear Information System (INIS)

    Dunaevsky, A.; Fisch, N.J.

    2003-01-01

    The initial density and electron temperature at the surface of a ferroelectric plasma source were deduced from floating probe measurements in an expanding plasma. The method exploits negative charging of the floating probe capacitance by fast flows before the expanding plasma reaches the probe. The temporal profiles of the plasma density can be obtained from the voltage traces of the discharge of the charged probe capacitance by the ion current from the expanding plasma. The temporal profiles of the plasma density, at two different distances from the surface of the ferroelectric plasma source, could be further fitted by using the density profiles for the expanding plasma. This gives the initial values of the plasma density and electron temperature at the surface. The method could be useful for any pulsed discharge, which is accompanied by considerable electromagnetic noise, if the initial plasma parameters might be deduced from measurements in expanding plasma

  4. Transient plasma injections in the dayside magnetosphere: one-to-one correlated observations by Cluster and SuperDARN

    Directory of Open Access Journals (Sweden)

    A. Marchaudon

    2004-01-01

    Full Text Available Conjunctions in the cusp between the four Cluster spacecraft and SuperDARN ground-based radars offer unique opportunities to compare the signatures of transient plasma injections simultaneously in the high-altitude dayside magnetosphere and in the ionosphere. We report here on such observations on 17 March 2001, when the IMF initially northward and duskward, turns southward and dawnward for a short period. The changes in the convection direction at Cluster are well correlated with the interplanetary magnetic field (IMF By variations. Moreover, the changes in the ionosphere follow those in the magnetosphere, with a 2–3min delay. When mapped into the ionosphere, the convection velocity at Cluster is about 1.5 times larger than measured by SuperDARN. In the high-altitude cusp, field and particle observations by Cluster display the characteristic signatures of plasma injections into the magnetosphere suggestive of Flux Transfer Events (FTEs. Simultaneous impulsive and localized convection plasma flows are observed in the ionospheric cusp by the HF radars. A clear one-to-one correlation is observed for three successive injections, with a 2–3min delay between the magnetospheric and ionospheric observations. For each event, the drift velocity of reconnected flux tubes (phase velocity has been compared in the magnetosphere and in the ionosphere. The drift velocity measured at Cluster is of the order of 400–600ms–1 when mapped into the ionosphere, in qualitative agreement with SuperDARN observations. Finally, the reconnected flux tubes are elongated in the north-south direction, with an east-west dimension of 30–60km in the ionosphere from mapped Cluster observations, which is consistent with SuperDARN observations, although slightly smaller. Key words. Ionosphere (plasma convection – Magnetospheric physics (magnetopause, cusp, and boundary layers; magnetosphere-ionosphere interactions

  5. Observation of refraction and convergence of ion acoustic waves in a plasma with a temperature gradient

    International Nuclear Information System (INIS)

    Nishida, Y.; Hirose, A.

    1977-01-01

    The refraction and convergence of ion acoustic waves are experimentally investigated in a magnetized plasma with an electron temperature gradient. When ion acoustic waves are launched parallel to the field lines the waves converge toward the interior of the plasma column where the electron temperature is lower, in good agreement with theoretical prediction. Wave interference is also observed. (author)

  6. Effects of pulsed electric field on ULQ and RFP plasmas

    International Nuclear Information System (INIS)

    Watanabe, M.; Saito, K.; Suzuki, T.

    1997-01-01

    Dynamo activity and self-organization processes are investigated using the application of pulsed poloidal and toroidal electric fields on ULQ and RFP plasmas. Synchronized to the application of the pulsed electric fields, the remarkable responses of the several plasma parameters are observed. The plasma has a preferential magnetic field structure, and the external perturbation activates fluctuation to maintain the structure through dynamo effect. This process changes the total dissipation with the variation of magnetic helicity in the system, showing that self organization accompanies an enhanced dissipation. (author)

  7. Influence of the low-frequency source parameters on the plasma characteristics in a dual frequency capacitively coupled plasma reactor: Two dimensional simulations

    Institute of Scientific and Technical Information of China (English)

    Xiang Xu; Hao Ge; Shuai Wang; Zhongling Dai; Younian Wang; Aimin Zhu

    2009-01-01

    A two-dimensional (2D) fluid model is presented to study the discharge of argon in a dual frequency capacitively coupled plasma (CCP) reactor. We are interested in the influence of low-frequency (LF) source parameters such as applied voltage amplitudes and low frequencies on the plasma characteristics. In this paper, the high frequency is set to 60 MHz with voltage 50 V. The simulations were carried out for low frequencies of 1, 2 and 6 MHz with LF voltage 100 V, and for LF voltages of 60, 90 and 120 V with low frequency 2 MHz. The results of 2D distributions of electric field and ion density, the ion flux impinging on the substrate and the ion energy on the powered electrode are shown. As the low frequency increases, two sources become from uncoupling to coupling, When two sources are uncoupling, the increase in LF has little impact on the plasma characteristics, but when two sources are coupling, the increase in LF decreases the uniformities of ion density and ion flux noticeably. It is also found that with the increase in LF voltage, the uniformities in the radial direction of ion density distribution and ion flux at the powered electrode decreases significantly, and the energy of ions bombarding on the powered electrode increases significantly.

  8. Westward tilt of low-latitude plasma blobs as observed by the Swarm constellation

    DEFF Research Database (Denmark)

    Park, Jaeheung; Luehr, Hermann; Michaelis, Ingo

    2015-01-01

    In this study we investigate the three-dimensional structure of low-latitude plasma blobs using multi-instrument and multisatellite observations of the Swarm constellation. During the early commissioning phase the Swarm satellites were flying at the same altitude with zonal separation of about 0...

  9. Exploiting Laboratory and Heliophysics Plasma Synergies

    Directory of Open Access Journals (Sweden)

    Jill Dahlburg

    2010-05-01

    Full Text Available Recent advances in space-based heliospheric observations, laboratory experimentation, and plasma simulation codes are creating an exciting new cross-disciplinary opportunity for understanding fast energy release and transport mechanisms in heliophysics and laboratory plasma dynamics, which had not been previously accessible. This article provides an overview of some new observational, experimental, and computational assets, and discusses current and near-term activities towards exploitation of synergies involving those assets. This overview does not claim to be comprehensive, but instead covers mainly activities closely associated with the authors’ interests and reearch. Heliospheric observations reviewed include the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI on the National Aeronautics and Space Administration (NASA Solar Terrestrial Relations Observatory (STEREO mission, the first instrument to provide remote sensing imagery observations with spatial continuity extending from the Sun to the Earth, and the Extreme-ultraviolet Imaging Spectrometer (EIS on the Japanese Hinode spacecraft that is measuring spectroscopically physical parameters of the solar atmosphere towards obtaining plasma temperatures, densities, and mass motions. The Solar Dynamics Observatory (SDO and the upcoming Solar Orbiter with the Heliospheric Imager (SoloHI on-board will also be discussed. Laboratory plasma experiments surveyed include the line-tied magnetic reconnection experiments at University of Wisconsin (relevant to coronal heating magnetic flux tube observations and simulations, and a dynamo facility under construction there; the Space Plasma Simulation Chamber at the Naval Research Laboratory that currently produces plasmas scalable to ionospheric and magnetospheric conditions and in the future also will be suited to study the physics of the solar corona; the Versatile Toroidal Facility at the Massachusetts Institute of Technology that

  10. Electric Field and Plasma Density Observations of Irregularities and Plasma Instabilities in the Low Latitude Ionosphere Gathered by the C/NOFS Satellite

    Science.gov (United States)

    Pfaff, Robert F.; Freudenreich, H.; Rowland, D.; Klenzing, J.; Liebrecht, C.

    2012-01-01

    The Vector Electric Field Investigation (VEFI) on the C/NOFS equatorial satellite provides a unique data set which includes detailed measurements of irregularities associated with the equatorial ionosphere and in particular with spread-F depletions. We present vector AC electric field observations gathered on C/NOFS that address a variety of key questions regarding how plasma irregularities, from meter to kilometer scales, are created and evolve. The talk focuses on occasions where the ionosphere F-peak has been elevated above the C/NOFS satellite perigee of 400 km as solar activity has increased. In particular, during the equinox periods of 2011, the satellite consistently journeyed below the F-peak whenever the orbit was in the region of the South Atlantic anomaly after sunset. During these passes, data from the electric field and plasma density probes on the satellite have revealed two types of instabilities which had not previously been observed in the C/NOFS data set: The first is evidence for 400-500km-scale bottomside "undulations" that appear in the density and electric field data. In one case, these large scale waves are associated with a strong shear in the zonal E x B flow, as evidenced by variations in the meridional (outward) electric fields observed above and below the F-peak. These undulations are devoid of smaller scale structures in the early evening, yet appear at later local times along the same orbit associated with fully-developed spread-F with smaller scale structures. This suggests that they may be precursor waves for spread-F, driven by a collisional shear instability, following ideas advanced previously by researchers using data from the Jicamarca radar. A second result is the appearance of km-scale irregularities that are a common feature in the electric field and plasma density data that also appear when the satellite is near or below the F-peak at night. The vector electric field instrument on C/NOFS clearly shows that the electric field

  11. Noninvasive in vivo plasma volume and hematocrit in humans: observing long-term baseline behavior to establish homeostasis for intravascular volume and composition

    Science.gov (United States)

    Dent, Paul; Deng, Bin; Goodisman, Jerry; Peterson, Charles M.; Narsipur, Sriram; Chaiken, J.

    2016-04-01

    A new device incorporating a new algorithm and measurement process allows simultaneous noninvasive in vivo monitoring of intravascular plasma volume and red blood cell volume. The purely optical technique involves probing fingertip skin with near infrared laser light and collecting the wavelength shifted light, that is, the inelastic emission (IE) which includes the unresolved Raman and fluorescence, and the un-shifted emission, that is, the elastic emission (EE) which includes both the Rayleigh and Mie scattered light. Our excitation and detection geometry is designed so that from these two simultaneous measurements we can calculate two parameters within the single scattering regime using radiation transfer theory, the intravascular plasma volume fraction and the red blood cell volume fraction. Previously calibrated against a gold standard FDA approved device, 2 hour monitoring sessions on three separate occasions over a three week span for a specific, motionless, and mostly sleeping individual produced 3 records containing a total of 5706 paired measurements of hematocrit and plasma volume. The average over the three runs, relative to the initial plasma volume taken as 100%, of the plasma volume±1σ was 97.56+/-0.55 or 0.56%.For the same three runs, the average relative hematocrit (Hct), referenced to an assumed initial value of 28.35 was 29.37+/-0.12 or stable to +/-0.4%.We observe local deterministic circulation effects apparently associated with the pressure applied by the finger probe as well as longer timescale behavior due to normal ebb and flow of internal fluids due to posture changes and tilt table induced gravity gradients.

  12. Experimental observation of a tripolar vortex in a plasma

    International Nuclear Information System (INIS)

    Okamoto, A.; Hara, K.; Nagaoka, K.; Yoshimura, S.; Vranjes, J.; Kono, M.; Tanaka, M. Y.

    2003-01-01

    A tripolar vortex, three aligned vortices with alternate signs of polarity of rotation, has been observed in a plasma for the first time. The tripolar vortex always appears with a deep density depression in the neutral particles, and the rotation direction of each vortex is opposite to that of the ExB rotation due to the ambipolar electric field. It is shown that a net momentum transfer during the charge-exchange interaction produces an effective force acting on the ions. The present experiment shows that this effective force may dominate the ambipolar-electric field and drive the anti-ExB vortical motion of ions

  13. Particle-in-cell plasma simulations of the modified two-stream instability

    Directory of Open Access Journals (Sweden)

    K. Schlegel

    1994-08-01

    Full Text Available We model the modified two-stream plasma instability occurring in the ionospheric E-region using a 2.5-dimensional particle-in-cell code. Compared to previous similar work we concentrate on simulated quantities that can easily be measured in the real ionosphere by coherent radars or rockets, such as the Doppler velocity, the backscattered power, backscattered spectra, aspect angle behaviour and electron temperature enhancement. Despite using a relatively small simulation model, we obtain remarkably good agreement between actual observed and simulated plasma parameters. The advantage of such a small system is that we were able to perform (other than in previous related work many simulation runs with different sets of input parameters, thus studying the unstable plasma under various conditions.

  14. Distant interplanetary wake of Venus: plasma observations from pioneer Venus

    International Nuclear Information System (INIS)

    Mihalov, J.D.; Barnes, A.

    1982-01-01

    In June 1979 the Pioneer Venus orbiter made its first series of passes through the distant solar wind wake of Venus at distances of 8--12 R/sub V/ behind the planet. During this period the plasma analyzer aboard the spacecraft detected disturbed magnetosheath plasma that intermittently disappeared and reappeared, suggesting a tattered, filamentary cavity trailing behind the planet. The magnetosheath dropouts almost always occurred inside the region of 'magnetotail' observed by Russell et al. Sporadic bursts of energetic ions (E/q> or approx. =4kV) are detected inside and, occasionally, outside the magnetotail; all such bursts are consistent with identification of the ion as O + of planetary origin moving at the local magnetosheath flow speed. The morphology of the plasma dropouts and of the O + bursts is analyzed in detail. The cavity appears to contract at times of high solar wind dynamic pressure. The intensity of the O + component is highly variable, and appears not to be strongly correlated with solar wind dynamic pressure. The most intense bursts correspond to a flux 7 ions cm - 2 s - 1 . This maximum flux, if steady and filling a cylinder 1 R/sub V/ in radius would correspond to a mass loss rate of 25 ions s - 1 ; the intermittency and variability of the flux suggest that the true mean loss rate is very much lower. The kinetic temperature of the O + component is estimated as 10 5 --10 6 K in order of magnitude

  15. Relation of zonal plasma drift and wind in the equatorial F region as derived from CHAMP observations

    Directory of Open Access Journals (Sweden)

    J. Park

    2013-06-01

    Full Text Available In this paper we estimate zonal plasma drift in the equatorial ionospheric F region without counting on ion drift meters. From June 2001 to June 2004 zonal plasma drift velocity is estimated from electron, neutral, and magnetic field observations of Challenging Mini-satellite Payload (CHAMP in the 09:00–20:00 LT sector. The estimated velocities are validated against ion drift measurements by the Republic of China Satellite-1/Ionospheric Plasma and Electrodynamics Instrument (ROCSAT-1/IPEI during the same period. The correlation between the CHAMP (altitude ~ 400 km estimates and ROCSAT-1 (altitude ~ 600 km observations is reasonably high (R ≈ 0.8. The slope of the linear regression is close to unity. However, the maximum westward drift and the westward-to-eastward reversal occur earlier for CHAMP estimates than for ROCSAT-1 measurements. In the equatorial F region both zonal wind and plasma drift have the same direction. Both generate vertical currents but with opposite signs. The wind effect (F region wind dynamo is generally larger in magnitude than the plasma drift effect (Pedersen current generated by vertical E field, thus determining the direction of the F region vertical current.

  16. Determination of discharge parameters via OES at the Linac4 H{sup −} ion source

    Energy Technology Data Exchange (ETDEWEB)

    Briefi, S., E-mail: stefan.briefi@physik.uni-augsburg.de [AG Experimentelle Plasmaphysik, Institut für Physik, Universität Augsburg, 86135 Augsburg (Germany); Fink, D.; Mattei, S.; Lettry, J. [Linac4 Ion Source Team, CERN-ABP, 1211 Geneva 23 (Switzerland); Fantz, U. [AG Experimentelle Plasmaphysik, Institut für Physik, Universität Augsburg, 86135 Augsburg (Germany); Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching (Germany)

    2016-02-15

    Optical emission spectroscopy (OES) measurements of the atomic Balmer series and the molecular Fulcher transition have been carried out at the Linac4 ion source in order to determine plasma parameters. As the spectroscopic system was only relatively calibrated, the data evaluation only yielded rough estimates of the plasma parameters (T{sub e} ≈ 1.2 eV, n{sub e} ≈ 1 × 10{sup 19} m{sup −3}, and n{sub H}/n{sub H{sub 2}} ≈ 0.5 at standard operational parameters). The analysis of the Fulcher transition revealed a non-thermal “hockey-stick” rotational population of the hydrogen molecules. At varying RF power, the measurements at the on-axis line of sight (LOS) showed a peak in the rotational temperatures between 25 and 40 kW of RF power, whereas a steady decrease with power was observed at a tilted LOS, indicating the presence of strong plasma parameter gradients.

  17. Orbit effects on impurity transport in a rotating tokamak plasma

    International Nuclear Information System (INIS)

    Wong, K.L.; Cheng, C.Z.

    1988-05-01

    Particle orbits in a rotating tokamak plasma are calculated from the equation of motion in the frame that rotates with the plasma. It is found that heavy particles in a rotating plasma can drift away from magnetic surfaces significantly faster with a higher bounce frequency, resulting in a diffusion coefficient much larger than that for a stationary plasma. Particle orbits near the surface of a rotating tokamak are also analyzed. Orbit effects indicate that more impurities can penetrate into a plasma rotating with counter-beam injection. Particle simulation is carried out with realistic experimental parameters and the results are in qualitative agreement with some experimental observations in the Tokamak Fusion Test Reactor (TFTR). 19 refs., 15 figs

  18. Flare plasma density determination using observed temperature profiles

    International Nuclear Information System (INIS)

    Garcia, H.A.

    1986-01-01

    Observed electron temperature variations derived from flux intensity ratios of whole-disk continuum soft X-ray spectra recorded by GOES satellites are presently subjected to an analysis that is based on the nonequilibrium energy balance equation in order to obtain the physical properties of a large solar flare from onset through the gradual phase. A self-similar formalism which reduces the nonlinear, second-order PDE in length and time to a more tractable, nonlinear, first-order Ricatti equation is invoked. Plasma density is the principal unknown variable contained in the Ricatti equation, which also contains first-order time derivatives and first- and second-order spatial derivatives of temperature. This methodology is presently applied to the moderate size flare of January 28, 1982, for which a density profile is deduced under various parametric conditions. 37 references

  19. Estimation of Flow Channel Parameters for Flowing Gas Mixed with Air in Atmospheric-pressure Plasma Jets

    Science.gov (United States)

    Yambe, Kiyoyuki; Saito, Hidetoshi

    2017-12-01

    When the working gas of an atmospheric-pressure non-equilibrium (cold) plasma flows into free space, the diameter of the resulting flow channel changes continuously. The shape of the channel is observed through the light emitted by the working gas of the atmospheric-pressure plasma. When the plasma jet forms a conical shape, the diameter of the cylindrical shape, which approximates the conical shape, defines the diameter of the flow channel. When the working gas flows into the atmosphere from the inside of a quartz tube, the gas mixes with air. The molar ratio of the working gas and air is estimated from the corresponding volume ratio through the relationship between the diameter of the cylindrical plasma channel and the inner diameter of the quartz tube. The Reynolds number is calculated from the kinematic viscosity of the mixed gas and the molar ratio. The gas flow rates for the upper limit of laminar flow and the lower limit of turbulent flow are determined by the corresponding Reynolds numbers estimated from the molar ratio. It is confirmed that the plasma jet length and the internal plasma length associated with strong light emission increase with the increasing gas flow rate until the rate for the upper limit of laminar flow and the lower limit of turbulent flow, respectively. Thus, we are able to explain the increasing trend in the plasma lengths with the diameter of the flow channel and the molar ratio by using the cylindrical approximation.

  20. The nonextensive parameter for nonequilibrium electron gas in an electromagnetic field

    International Nuclear Information System (INIS)

    Yu, Haining; Du, Jiulin

    2014-01-01

    The nonextensive parameter for nonequilibrium electron gas of the plasma in an electromagnetic field is studied. We exactly obtained an expression of the q-parameter based on Boltzmann kinetic theories for plasmas, where Coulombian interactions and Lorentz forces play dominant roles. We show that the q-parameter different from unity is related by an equation to temperature gradient, electric field strength, magnetic induction as well as overall bulk velocity of the gas. The effect of the magnetic field on the q-parameter depends on the overall bulk velocity. Thus the q-parameter for the electron gas in an electromagnetic field represents the nonequilibrium nature or nonisothermal configurations of the plasma with electromagnetic interactions. - Highlights: • An expression of the q-parameter is obtained for nonequilibrium plasma with electromagnetic interactions. • The q-parameter is related to temperature gradient, electric field strength, magnetic induction as well as overall bulk velocity of the plasma. • The q-parameter represents the nonequilibrium nature of the complex plasma with electromagnetic interactions

  1. The nonextensive parameter for nonequilibrium electron gas in an electromagnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Haining; Du, Jiulin, E-mail: jldu@tju.edu.cn

    2014-11-15

    The nonextensive parameter for nonequilibrium electron gas of the plasma in an electromagnetic field is studied. We exactly obtained an expression of the q-parameter based on Boltzmann kinetic theories for plasmas, where Coulombian interactions and Lorentz forces play dominant roles. We show that the q-parameter different from unity is related by an equation to temperature gradient, electric field strength, magnetic induction as well as overall bulk velocity of the gas. The effect of the magnetic field on the q-parameter depends on the overall bulk velocity. Thus the q-parameter for the electron gas in an electromagnetic field represents the nonequilibrium nature or nonisothermal configurations of the plasma with electromagnetic interactions. - Highlights: • An expression of the q-parameter is obtained for nonequilibrium plasma with electromagnetic interactions. • The q-parameter is related to temperature gradient, electric field strength, magnetic induction as well as overall bulk velocity of the plasma. • The q-parameter represents the nonequilibrium nature of the complex plasma with electromagnetic interactions.

  2. Plasma parameters and electromagnetic forces induced by the magneto hydro dynamic interaction in a hypersonic argon flow experiment

    International Nuclear Information System (INIS)

    Cristofolini, Andrea; Neretti, Gabriele; Borghi, Carlo A.

    2012-01-01

    This work proposes an experimental analysis on the magneto hydro dynamic (MHD) interaction induced by a magnetic test body immersed into a hypersonic argon flow. The characteristic plasma parameters are measured. They are related to the voltages arising in the Hall direction and to the variation of the fluid dynamic properties induced by the interaction. The tests have been performed in a hypersonic wind tunnel at Mach 6 and Mach 15. The plasma parameters are measured in the stagnation region in front of the nozzle of the wind tunnel and in the free stream region at the nozzle exit. The test body has a conical shape with the cone axis in the gas flow direction and the cone vertex against the flow. It is placed at the nozzle exit and is equipped with three permanent magnets. In the configuration adopted, the Faraday current flows in a closed loop completely immersed into the plasma of the shock layer. The electric field and the pressure variation due to MHD interaction have been measured on the test body walls. Microwave adsorption measurements have been used for the determination of the electron number density and the electron collision frequency. Continuum recombination radiation and line radiation emissions have been detected. The electron temperature has been determined by means of the spectroscopic data by using different methods. The electron number density has been also determined by means of the Stark broadening of H α and the H β lines. Optical imaging has been utilized to visualize the pattern of the electric current distribution in the shock layer around the test body. The experiments show a considerable effect of the electromagnetic forces produced by the MHD interaction acting on the plasma flow around the test body. A comparison of the experimental data with simulation results shows a good agreement.

  3. Characterization of the plasma in magnetic multidipole discharges

    International Nuclear Information System (INIS)

    Ferreira, J.G.

    1988-09-01

    In this work, a caracterization of the discharge of the quiescent plasma machine of INPE, and an identification of the most relevant processes in the definition of its plasma properties, were achieved. Measurements of plasma potential, the floating potential, the temperature of the electrons, and the density of the plasma, for pressures ranging from 10 -3 to 10 -1 Pa and for discharge potentials for 45V to 120V were acomplished. These measurements were made with a Langmuir spherical probe with 1mm in diameter. In the whole range of operation the presence of two populations of electrons with distinct temperatures in the energy range from 1 to 10eV was observed, although for pressures approaching 10 -1 Pa the plasma tended to a single population of electrons with temperature of 1eV. The difference between plasma and floating potentials was observed to become smaller as the pressure raised, and the potential difference between plasma and anode reached a value around 2V when pressure raised above 10 -2 Pa. The plasma density increases approximately linearly with pressure, for values below 10 -2 Paa, but above 10 -1 Pa its increase with pressure is quite reduced. A study on the collision processes in the plasma volume and on loss processes to surfaces allowed to interpret qualitatively the observed plasma behavior and to estimate, by means of simple expressions, some of the plasma parameters. The loss areas for ions and primary electrons were estimated from experimental results. A simple quantitative model which allows the calculation of plasma density in the whole range of operation, reproduced the correct order of magnitude of experimental values. However, an additional work, both theoretical and experimental, is required to obtain better agreement between experimental and theoretical values. (author) [pt

  4. Predicting Plasma Glucose From Interstitial Glucose Observations Using Bayesian Methods

    DEFF Research Database (Denmark)

    Hansen, Alexander Hildenbrand; Duun-Henriksen, Anne Katrine; Juhl, Rune

    2014-01-01

    One way of constructing a control algorithm for an artificial pancreas is to identify a model capable of predicting plasma glucose (PG) from interstitial glucose (IG) observations. Stochastic differential equations (SDEs) make it possible to account both for the unknown influence of the continuous...... glucose monitor (CGM) and for unknown physiological influences. Combined with prior knowledge about the measurement devices, this approach can be used to obtain a robust predictive model. A stochastic-differential-equation-based gray box (SDE-GB) model is formulated on the basis of an identifiable...

  5. Plasma Clouds and Snowplows: Bulk Plasma Escape from Mars Observed by MAVEN

    Science.gov (United States)

    Halekas, J. S.; Brain, D. A.; Ruhunusiri, S.; McFadden, J. P.; Mitchell, D. L.; Mazelle, C.; Connerney, J. E. P.; Harada, Y.; Hara, T.; Espley, J. R.; hide

    2016-01-01

    We present initial Mars Atmosphere and Volatile EvolutioN (MAVEN) observations and preliminary interpretation of bulk plasma loss from Mars. MAVEN particle and field measurements show that planetary heavy ions derived from the Martian atmosphere can escape in the form of discrete coherent structures or "clouds." The ions in these clouds are unmagnetized or weakly magnetized, have velocities well above the escape speed, and lie directly downstream from magnetic field amplifications, suggesting a "snowplow" effect. This postulated escape process, similar to that successfully used to explain the dynamics of active gas releases in the solar wind and terrestrial magnetosheath, relies on momentum transfer from the shocked solar wind protons to the planetary heavy ions, with the electrons and magnetic field acting as intermediaries. Fluxes of planetary ions on the order of 10(exp 7)/sq cm/s can escape by this process, and if it operates regularly, it could contribute 10-20% of the current ion escape from Mars.

  6. Study of single and binary ion plasma expansion into laboratory-generated plasma wakes

    International Nuclear Information System (INIS)

    Wright, K.H. Jr.

    1988-02-01

    Plasma expansion into the wake of a large rectangular plate immersed in a collisionless, supersonic plasma was investigated in laboratory experiments. The experimental conditions address both single ion and binary ion plasma flows for the case of a body whose size is large in comparison with the Debye length, when the potential difference between the body and the plasma is relatively small. A new plasma source was developed to generate equi-velocity, binary ion plasma flows, which allows access to new parameter space that have previously been unavailable for laboratory studies. Specifically, the new parameters are the ionic mass ratio and the ionic component density ratio. In a series of experiments, a krypton-neon plasma is employed where the ambient density ratio of neon to krypton is varied more than an order of magnitude. The expansion in both the single ion and binary ion plasma cases is limited to early times, i.e., a few ion plasma periods, by the combination of plasma density, plasma drift speed, and vacuum chamber size, which prevented detailed comparison with self-similar theory

  7. A plasma deflagration accelerator as a platform for laboratory astrophysics

    Science.gov (United States)

    Underwood, Thomas C.; Loebner, Keith T. K.; Cappelli, Mark A.

    2017-06-01

    The replication of astrophysical flows in the laboratory is critical for isolating particular phenomena and dynamics that appear in complex, highly-coupled natural systems. In particular, plasma jets are observed in astrophysical contexts at a variety of scales, typically at high magnetic Reynolds number and driven by internal currents. In this paper, we present detailed measurements of the plasma parameters within deflagration-produced plasma jets, the scaling of these parameters against both machine operating conditions and the corresponding astrophysical phenomena. Using optical and spectroscopic diagnostics, including Schlieren cinematography, we demonstrate the production of current-driven plasma jets of ∼100 km/s and magnetic Reynolds numbers of ∼100, and discuss the dynamics of their acceleration into vacuum. The results of this study will contribute to the reproduction of various types of astrophysical jets in the laboratory and indicate the ability to further probe active research areas such as jet collimation, stability, and interaction.

  8. Self-compression of intense short laser pulses in relativistic magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Olumi, M.; Maraghechi, B., E-mail: behrouz@aut.ac.ir [Department of Physics, Amirkabir University of Technology, Post code 15916-34311 Tehran (Iran, Islamic Republic of)

    2014-11-15

    The compression of a relativistic Gaussian laser pulse in a magnetized plasma is investigated. By considering relativistic nonlinearity and using non-linear Schrödinger equation with paraxial approximation, a second-order differential equation is obtained for the pulse width parameter (in time) to demonstrate the longitudinal pulse compression. The compression of laser pulse in a magnetized plasma can be observed by the numerical solution of the equation for the pulse width parameter. The effects of magnetic field and chirping are investigated. It is shown that in the presence of magnetic field and negative initial chirp, compression of pulse is significantly enhanced.

  9. Asymmetric SOL Current in Vertically Displaced Plasma

    Science.gov (United States)

    Cabrera, J. D.; Navratil, G. A.; Hanson, J. M.

    2017-10-01

    Experiments at the DIII-D tokamak demonstrate a non-monotonic relationship between measured scrape-off layer (SOL) currents and vertical displacement event (VDE) rates with SOL currents becoming largely n=1 dominant as plasma is displaced by the plasma control system (PCS) at faster rates. The DIII-D PCS is used to displace the magnetic axis 10x slower than the intrinsic growth time of similar instabilities in lower single-null plasmas. Low order (n VDE instabilities observed when vertical control is disabled. Previous inquiry shows VDE asymmetry characterized by SOL current fraction and geometric parameters of tokamak plasmas. We note that, of plasmas displaced by the PCS, short displacement time scales near the limit of the PCS temporal control appear to result in larger n=1/n=2 asymmetries. Work supported under USDOE Cooperative Agreement DE-FC02-04ER54698 and DE-FG02-04ER54761.

  10. Quasi-equilibria and plasma chemical similarity in non-isothermal reactive plasmas

    International Nuclear Information System (INIS)

    Miethke, F.; Rutscher, A.; Wagner, H.E.

    2000-01-01

    With regard to the output of stable products the mode of operation of non-isothermal plasma chemical reactors shows physical and chemical well defined states, which represent limiting cases and may be interpreted as quasi-equilibrium states. The occurrence and the characteristics of these states, meanwhile more than once observed and described, are demonstrated by an instructive model reaction. Within the frame of the so-called Macroscopic Kinetics a central parameter is dominating the reactor operation. This result may be generalized and is linked up to the application of similarity principles for the reactor operation. After the general formulation of such principles, starting from the balance equations of particles and energy, a dimensionless similarity parameter is formulated, characterizing the composition of the effluent gas of the reactor. The applicability of this parameter is demonstrated by experimental examples. (Authors)

  11. Equation of state of partially-ionized dense plasmas

    International Nuclear Information System (INIS)

    Rogers, F.J.

    1989-01-01

    This paper describes methods for calculating the equation of state of partially-ionized dense plasmas. The term dense plasma is used rather than strongly coupled plasma, since it is possible that at plasma conditions such that only a few levels can be observed spectroscopically the plasma coupling parameters are not large. Due mainly to their importance in theoretical astrophysics, the properties of partially ionized plasmas have been of interest for a long while. More recently, this interest has intensified due to the development of methods for producing partially ionized plasmas in the laboratory. This has opened up large programs of experimental investigation and of practical application. In this paper we consider detailed statistical mechanical methods that explicitly treat the distribution over ionic species and their energy level structure. These detailed approaches are generally characterized as being in the ''chemical picture'' when a free energy expression is minimized or in the ''physical picture'' when the starting point is the grand canonical ensemble. 52 refs., 2 tabs

  12. 2XIIB plasma confinement experiments

    International Nuclear Information System (INIS)

    Coensgen, F.H.; Clauser, J.F.; Correll, D.L.

    1976-01-01

    This paper reports results of 2XIIB neutral-beam injection experiments with plasma-stream stabilization. The plasma stream is provided either by a pulsed plasma generator located on the field lines outside the plasma region or by ionization of neutral gas introduced at the mirror throat. In the latter case, the gas is ionized by the normal particle flux through the magnetic mirror. A method of plasma startup and sustenance in a steady-state magnetic field is reported in which the plasma stream from the pulsed plasma generator serves as the initial target for the neutral beams. After an energetic plasma of sufficient density is established, the plasma generator stream is replaced by the gas-fed stream. Lifetimes of the stabilized plasma increase with plasma temperature in agreement with the plasma stabilization of the drift-cyclotron loss-cone mode. The following plasma parameters are attained using the pulsed plasma generator for stabilization: n approximately 5 x 10 13 cm -3 , anti W/sub i/ approximately 13 keV, T/sub e/ = 140 eV, and ntau/sub p/ approximately 7 x 10 10 cm -3 .s. With the gas feed, the mean deuterium ion energy is 9 keV and the peak density n approximately 10 14 cm -3 . In the latter case, the energy confinement parameter reaches ntau/sub E/ = 7 x 10 10 cm -3 .s, and the particle confinement parameter reaches ntau/sub p/ = 1 x 10 11 cm -3 .s

  13. Testing backreaction effects with observational Hubble parameter data

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Shu-Lei; Teng, Huan-Yu [Beijing Normal University, Department of Astronomy, Beijing (China); Wan, Hao-Yi [Beijing Normal University, Department of Astronomy, Beijing (China); National Astronomical Observatories, Chinese Academy of Sciences, Beijing (China); Yu, Hao-Ran [Shanghai Jiao Tong University, Tsung-Dao Lee Institute, Shanghai (China); Zhang, Tong-Jie [Dezhou University, Dezhou (China); Beijing Normal University, Department of Astronomy, Beijing (China)

    2018-02-15

    The spatially averaged inhomogeneous Universe includes a kinematical backreaction term Q{sub D} that is relate to the averaged spatial Ricci scalar left angle R right angle {sub D} in the framework of general relativity. Under the assumption that Q{sub D} and left angle R right angle {sub D} obey the scaling laws of the volume scale factor a{sub D}, a direct coupling between them with a scaling index n is remarkable. In order to explore the generic properties of a backreaction model for explaining the accelerated expansion of the Universe, we exploit two metrics to describe the late time Universe. Since the standard FLRW metric cannot precisely describe the late time Universe on small scales, the template metric with an evolving curvature parameter κ{sub D}(t) is employed. However, we doubt the validity of the prescription for κ{sub D}, which motivates us apply observational Hubble parameter data (OHD) to constrain parameters in dust cosmology. First, for FLRW metric, by getting best-fit constraints of Ω{sup D{sub 0m}} = 0.25{sup +0.03}{sub -0.03}, n = 0.02{sup +0.69}{sub -0.66}, and H{sub D{sub 0}} = 70.544{sup +4.24}{sub -3.97} km s{sup -1} Mpc{sup -1}, the evolutions of parameters are explored. Second, in template metric context, by marginalizing over H{sub D{sub 0}} as a prior of uniform distribution, we obtain the best-fit values of n = -1.22{sup +0.68}{sub -0.41} and Ω{sub m}{sup D{sub 0}} = 0.12{sup +0.04}{sub -0.02}. Moreover, we utilize three different Gaussian priors of H{sub D{sub 0}}, which result in different best-fits of n, but almost the same best-fit value of Ω{sub m}{sup D{sub 0}} ∝ 0.12. Also, the absolute constraints without marginalization of parameter are obtained: n = -1.1{sup +0.58}{sub -0.50} and Ω{sub m}{sup D{sub 0}} = 0.13 ± 0.03. With these constraints, the evolutions of the effective deceleration parameter q{sup D} indicate that the backreaction can account for the accelerated expansion of the Universe without involving extra

  14. Collisional transport in nonneutral plasmas

    International Nuclear Information System (INIS)

    Dubin, D.H.E.

    1999-01-01

    Classical transport theory grossly underestimates collisionally-driven cross-field transport for plasmas in the parameter regime of r c D , where r c ≡ v-bar/Ω c , λ D 2 ≡ T/4πe 2 n. In current experiments operating in this regime, cross-field test particle transport is observed to be a factor of 10 larger than the prediction of classical theory. Heat conduction is enhanced by up to 300 times over classical theory, and viscosity is up to 10 4 times larger. New guiding center theories of transport due to long-range collisions have been developed that agree with the measurements. Theory also predicts that emission and absorption of plasma waves may further enhance the thermal conduction and viscosity, providing a possible mechanism for anomalous thermal conductivity in the electron channel of fusion plasmas. (author)

  15. Real time plasma control experiments using the JET auxiliary plasma heating systems as the actuator

    International Nuclear Information System (INIS)

    Zornig, N.H.

    1999-01-01

    The role of the Real Time Power Control system (RTPC) in the Joint European Torus (JET) is described in depth. The modes of operation are discussed in detail and a number of successful experiments are described. These experiments prove that RTPC can be used for a wide range of experiments, including: (1) Feedback control of plasma parameters in real time using Ion Cyclotron Resonance Heating (ICRH) or Neutral Beam Heating (NBH) as the actuator in various JET operating regimes. It is demonstrated that in a multi-parameter space it is not sufficient to control one global plasma parameter in order to avoid performance limiting events. (2) Restricting neutron production and subsequent machine activation resulting from high performance pulses. (3) The simulation of α-particle heating effects in a DT-plasma in a D-only plasma. The heating properties of α-particles are simulated using ICRH-power, which is adjusted in real time. The simulation of α-particle heating in JET allows the effects of a change in isotopic mass to be separated from α-particle heating. However, the change in isotopic mass of the plasma ions appears to affect not only the global energy confinement time (τ E ) but also other parameters such as the electron temperature at the plasma edge. This also affects τ E , making it difficult to make a conclusive statement about any isotopic effect. (4) For future JET experiments a scheme has been designed which simulates the behaviour of a fusion reactor experimentally. The design parameters of the International Thermonuclear Experimental Reactor (ITER) are used. In the proposed scheme the most relevant dimensionless plasma parameters are similar in JET and ITER. It is also shown how the amount of heating may be simulated in real time by RTPC using the electron temperature and density as input parameters. The results of two demonstration experiments are presented. (author)

  16. Expanding plasma jet in a vacuum vessel

    International Nuclear Information System (INIS)

    Chutov, Yu.I.; Kravchenko, A.Yu.; Yakovetskij, V.S.

    1998-01-01

    The paper deals with numerical calculations of parameters of a supersonic quasi-neutral argon plasma jet expanding into a cylindrical vacuum vessel and interacting with its inner surface. A modified method of large particles was used, the complex set of hydrodynamic equations being broken into simpler components, each of which describes a separate physical process. Spatial distributions of the main parameters of the argon plasma jet were simulated at various times after the jet entering the vacuum vessel, the parameters being the jet velocity field, the full plasma pressure, the electron temperature, the temperature of heavy particles, and the degree of ionization. The results show a significant effect of plasma jet interaction on the plasma parameters. The jet interaction with the vessel walls may result e.g. in excitation of shock waves and rotational plasma motions. (J.U.)

  17. 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.

  18. Dust in flowing magnetized plasma

    International Nuclear Information System (INIS)

    Pandey, Birendra P.; Samarian, Alex A.; Vladimirov, Sergey V.

    2009-01-01

    Plasma flows occur in almost every laboratory device and interactions of flowing plasmas with near-wall impurities and/or dust significantly affects the efficiency and lifetime of such devices. The charged dust inside the magnetized flowing plasma moves primarily under the influence of the plasma drag and electric forces. Here, the charge on the dust, plasma potential, and plasma density are calculated self-consistently. The electrons are assumed non-Boltzmannian and the effect of electron magnetization and electron-atom collisions on the dust charge is calculated in a self-consistent fashion. For various plasma magnetization parameters viz. the ratio of the electron and ion cyclotron frequencies to their respective collision frequencies, plasma-atom and ionization frequencies, the evolution of the plasma potential and density in the flow region is investigated. The variation of the dust charge profile is shown to be a sensitive function of plasma parameters. (author)

  19. Self-organized ignition of a tokamak plasma

    International Nuclear Information System (INIS)

    Schoepf, K.

    2007-01-01

    The continuous progress in the attainment of plasma parameters required for establishing nuclear fusion in magnetically confined plasmas as well as the prospect of feasible steady-state operation has instigated the interest in the physics of burning plasmas [1]. Aside from the required plasma current drive, fusion energy production with tokamaks demands particular attention to confinement and fuelling regimes in order to maintain the plasma density n and temperature T at favourable values matching with specific requirements such as the triple product nτ E T, where τ E represents the plasma energy confinement time. The identification of state and parameter space regions capable of ignited fusion plasma operation is evidently crucial if significant energy gains are to be realized over longer periods. Examining the time-evolving state of tokamak fusion plasma in a parameter space spanned by the densities of plasma constituents and their temperatures has led to the formation of an ignition criterion [2] fundamentally different from the commonly used static patterns. The incorporation of non-stationary particle and energy balances into the analysis here, the application of a 'soft' Troyon beta limit [3], the consideration of actual fusion power deposition [4,5] and its effect of reducing τ E are seen to significantly influence the fusion burn dynamics and to shape the ignition conditions. The presented investigation refers to a somewhat upgraded (to achieve ignition) ITER-like tokamak plasma and uses volume averages of locally varying quantities and processes. The resulting ignition criterion accounts for the dynamic evolution of a reacting plasma controlled by heating and fuel feeding. Interestingly, also self-organized ignition can be observed: a fusion plasma possessing a density and temperature above a distinct separatrix in the considered parameter phase space is seen to evolve - without external heating and hence practically by itself - towards an ignited

  20. Energetic ion emission in a positive polarity nanosecond plasma opening switch

    Energy Technology Data Exchange (ETDEWEB)

    Sarfaty, M [Univ. of Wisconsin, Madison, WI (United States); Krasik, Ya E; Weingarten, A; Fruchtman, A; Maron, Y [Weizmann Institute of Science, Rehovot (Israel). Department of Physics

    1997-12-31

    The emission was studied of energetic ions from the plasma in a coaxial Plasma Opening Switch (POS) powered by a 300 kV, 15 kA, 90 ns positive polarity pulse. Fluxes lasting 2 - 3 ns of ions flowing radially onto the cathode were observed at all axial locations of the switch plasma within 5 ns of the beginning of the upstream POS current. It is suggested that the termination of this ion flux is due to the formation of a cathode plasma, which is consistent with our spectroscopic measurements. Later in the pulse, longer duration (100 ns) ion fluxes were observed radially, first appearing in the generator side of the switch plasma. Fluxes 30 - 40 ns long of ions flowing axially towards the POS load at velocities (2{+-}1) x 10{sup 8} cm/s were also observed. The dependences of the start time of the axial ion flow, of the ion velocities, and of the ion flux on the POS operation parameters were studied. (author). 6 figs., 5 refs.

  1. Energetic ion emission in a positive polarity nanosecond plasma opening switch

    International Nuclear Information System (INIS)

    Sarfaty, M.; Krasik, Ya.E.; Weingarten, A.; Fruchtman, A.; Maron, Y.

    1996-01-01

    The emission was studied of energetic ions from the plasma in a coaxial Plasma Opening Switch (POS) powered by a 300 kV, 15 kA, 90 ns positive polarity pulse. Fluxes lasting 2 - 3 ns of ions flowing radially onto the cathode were observed at all axial locations of the switch plasma within 5 ns of the beginning of the upstream POS current. It is suggested that the termination of this ion flux is due to the formation of a cathode plasma, which is consistent with our spectroscopic measurements. Later in the pulse, longer duration (100 ns) ion fluxes were observed radially, first appearing in the generator side of the switch plasma. Fluxes 30 - 40 ns long of ions flowing axially towards the POS load at velocities (2±1) x 10 8 cm/s were also observed. The dependences of the start time of the axial ion flow, of the ion velocities, and of the ion flux on the POS operation parameters were studied. (author). 6 figs., 5 refs

  2. Experimental observation of 3-D, impulsive reconnection events in a laboratory plasma

    Energy Technology Data Exchange (ETDEWEB)

    Dorfman, S.; Ji, H.; Yamada, M.; Yoo, J.; Lawrence, E.; Myers, C.; Tharp, T. D. [Center for Magnetic Self-Organization, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2014-01-15

    Fast, impulsive reconnection is commonly observed in laboratory, space, and astrophysical plasmas. In this work, impulsive, local, 3-D reconnection is identified for the first time in a laboratory current sheet. The two-fluid, impulsive reconnection events observed on the Magnetic Reconnection Experiment (MRX) [Yamada et al., Phys Plasmas 4, 1936 (1997)] cannot be explained by 2-D models and are therefore fundamentally three-dimensional. Several signatures of flux ropes are identified with these events; 3-D high current density regions with O-point structure form during a slow buildup period that precedes a fast disruption of the reconnecting current layer. The observed drop in the reconnection current and spike in the reconnection rate during the disruption are due to ejection of these flux ropes from the layer. Underscoring the 3-D nature of the events, strong out-of-plane gradients in both the density and reconnecting magnetic field are found to play a key role in this process. Electromagnetic fluctuations in the lower hybrid frequency range are observed to peak at the disruption time; however, they are not the key physics responsible for the impulsive phenomena observed. Important features of the disruption dynamics cannot be explained by an anomalous resistivity model. An important discrepancy in the layer width and force balance between the collisionless regime of MRX and kinetic simulations is also revisited. The wider layers observed in MRX may be due to the formation of flux ropes with a wide range of sizes; consistent with this hypothesis, flux rope signatures are observed down to the smallest scales resolved by the diagnostics. Finally, a 3-D two-fluid model is proposed to explain how the observed out-of-plane variation may lead to a localized region of enhanced reconnection that spreads in the direction of the out-of-plane electron flow, ejecting flux ropes from the layer in a 3-D manner.

  3. Kinetic parameters for plasma β-endorphin in lean and obese Zucker rats

    International Nuclear Information System (INIS)

    Rodd, D.; Farrell, P.A.; Caston, A.L.; Green, M.H.

    1991-01-01

    To determine plasma clearance kinetics for β-endorphin (BE) by empirical compartmental analysis, a bolus of radioactive labeled 125I-BE was rapidly injected into a carotid artery catheter of unanesthetized lean (L) and obese (O) Zucker rats. The plasma disappearance of 125I was followed over a 3-h period. A 3-component exponential equation provided the best fit for plasma data. Plasma transit times were very short (10 s); however, plasma fractional catabolic rate was much slower. Plasma mean residence time was similar for both groups (50 min) as was recycle time (1.3 min). These data suggest that BE plasma disappearance kinetics are similar in L and O rats

  4. Kinetic parameters for plasma. beta. -endorphin in lean and obese Zucker rats

    Energy Technology Data Exchange (ETDEWEB)

    Rodd, D.; Farrell, P.A.; Caston, A.L.; Green, M.H. (Department of Exercise and Sport Science, Pennsylvania State University, University Park (USA))

    1991-03-01

    To determine plasma clearance kinetics for {beta}-endorphin (BE) by empirical compartmental analysis, a bolus of radioactive labeled 125I-BE was rapidly injected into a carotid artery catheter of unanesthetized lean (L) and obese (O) Zucker rats. The plasma disappearance of 125I was followed over a 3-h period. A 3-component exponential equation provided the best fit for plasma data. Plasma transit times were very short (10 s); however, plasma fractional catabolic rate was much slower. Plasma mean residence time was similar for both groups (50 min) as was recycle time (1.3 min). These data suggest that BE plasma disappearance kinetics are similar in L and O rats.

  5. Observing atmospheric tides in Earth rotation parameters with VLBI

    Science.gov (United States)

    Girdiuk, Anastasiia; Böhm, Johannes; Schindelegger, Michael

    2015-04-01

    In this study, we assess the contribution of diurnal (S1) and semi-diurnal (S2) atmospheric tides to variations in Earth rotation by analyzing Very Long Baseline Interferometry (VLBI) observations. Particular emphasis is placed on the dependency of S1 and S2 estimates on varying settings in the a priori delay model. We use hourly Earth rotation parameters (ERP) of polar motion and UT1 as determined with the Vienna VLBI Software (VieVS) from 25 years of VLBI observations and we adjust diurnal and semi-diurnal amplitudes to the hourly ERP estimates after disregarding the effect of high-frequency ocean tides. Prograde and retrograde polar motion coefficients are obtained for several solutions differing in processing strategies (with/without thermal deformation, time span of observations, choice of a priori ERP model and celestial pole offsets) and we compare the corresponding harmonics with those derived from atmospheric and non-tidal oceanic angular momentum estimates.

  6. Ulysses solar wind plasma observations at high southerly latitudes.

    Science.gov (United States)

    Phillips, J L; Bame, S J; Feldman, W C; Gosling, J T; Hammond, C M; McComas, D J; Goldstein, B E; Neugebauer, M; Scime, E E; Suess, S T

    1995-05-19

    Solar wind plasma observations made by the Ulysses spacecraft through -80.2 degrees solar latitude and continuing equatorward to -40.1 degrees are summarized. Recurrent high-speed streams and corotating interaction regions dominated at middle latitudes. The speed of the solar wind was typically 700 to 800 kilometers per second poleward of -35 degrees . Corotating reverse shocks persisted farther south than did forward shocks because of the tilt of the heliomagnetic streamer belt. Sporadic coronal mass ejections were seen as far south as -60.5 degrees . Proton temperature was higher and the electron strahl was broader at higher latitudes. The high-latitude wind contained compressional, pressure-balanced, and Alfvénic structures.

  7. Effect of transient scrotal hyperthermia on sperm parameters, seminal plasma biochemical markers, and oxidative stress in men

    Directory of Open Access Journals (Sweden)

    Meng Rao

    2015-01-01

    Full Text Available In this experimental prospective study, we aimed to analyze the effect of transient scrotal hyperthermia on the male reproductive organs, from the perspective of sperm parameters, semen plasma biochemical markers, and oxidative stress, to evaluate whether different frequencies of heat exposure cause different degrees of damage to spermatogenesis. Two groups of volunteers (10 per group received testicular warming in a 43°C water bath 10 times, for 30 min each time: group 1: 10 consecutive days; group 2: once every 3 days. Sperm parameters, epididymis and accessory sex gland function, semen plasma oxidative stress and serum sex hormones were tested before treatment and in the 16-week recovery period after treatment. At last, we found an obvious reversible decrease in sperm concentration (P = 0.005 for Group 1 and P= 0.008 for Group 2 when the minimums were compared with baseline levels, the same below, motility (P = 0.009 and 0.021, respectively, the hypoosmotic swelling test score (P = 0.007 and 0.008, respectively, total acrosin activity (P = 0.018 and 0.009, respectively, and an increase in the seminal plasma malondialdehyde concentration (P = 0.005 and 0.017, respectively. The decrease of sperm concentration was greater for Group 2 than for Group 1 (P = 0.031. We concluded that transient scrotal hyperthermia seriously, but reversibly, negatively affected the spermatogenesis, oxidative stress may be involved in this process. In addition, intermittent heat exposure more seriously suppresses the spermatogenesis compared to consecutive heat exposure. This may be indicative for clinical infertility etiology analysis and the design of contraceptive methods based on heat stress.

  8. Enhanced relativistic self-focusing of Hermite-cosh-Gaussian laser beam in plasma under density transition

    International Nuclear Information System (INIS)

    Nanda, Vikas; Kant, Niti

    2014-01-01

    Enhanced and early relativistic self-focusing of Hermite-cosh-Gaussian (HChG) beam in the plasmas under density transition has been investigated theoretically using Wentzel-Kramers-Brillouin and paraxial ray approximation for mode indices m=0, 1, and 2. The variation of beam width parameter with normalized propagation distance for m=0, 1, and 2 is reported, and it is observed that strong self-focusing occurs as the HChG beam propagates deeper inside the nonlinear medium as spot size shrinks due to highly dense plasmas and the results are presented graphically. A comparative study between self-focusing of HChG beam in the presence and absence of plasmas density transition is reported. The dependency of beam width parameter on the normalized propagation distance for different values of decentered parameter “b” has also been presented graphically. For m=0 and 1, strong self-focusing is reported for b=1.8, and for m=2 and b=1.8, beam gets diffracted. The results obtained indicate the dependency of the self-focusing of the HChG beam on the selected values of decentered parameter. Moreover, proper selection of decentered parameter results strong self-focusing of HChG beam. Stronger self-focusing of laser beam is observed due to the presence of plasma density transition which might be very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, etc

  9. Enhanced relativistic self-focusing of Hermite-cosh-Gaussian laser beam in plasma under density transition

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, Vikas; Kant, Niti, E-mail: nitikant@yahoo.com [Department of Physics, Lovely Professional University, Phagwara 144411, Punjab (India)

    2014-04-15

    Enhanced and early relativistic self-focusing of Hermite-cosh-Gaussian (HChG) beam in the plasmas under density transition has been investigated theoretically using Wentzel-Kramers-Brillouin and paraxial ray approximation for mode indices m=0, 1, and 2. The variation of beam width parameter with normalized propagation distance for m=0, 1, and 2 is reported, and it is observed that strong self-focusing occurs as the HChG beam propagates deeper inside the nonlinear medium as spot size shrinks due to highly dense plasmas and the results are presented graphically. A comparative study between self-focusing of HChG beam in the presence and absence of plasmas density transition is reported. The dependency of beam width parameter on the normalized propagation distance for different values of decentered parameter “b” has also been presented graphically. For m=0 and 1, strong self-focusing is reported for b=1.8, and for m=2 and b=1.8, beam gets diffracted. The results obtained indicate the dependency of the self-focusing of the HChG beam on the selected values of decentered parameter. Moreover, proper selection of decentered parameter results strong self-focusing of HChG beam. Stronger self-focusing of laser beam is observed due to the presence of plasma density transition which might be very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, etc.

  10. Modelling and control of a tokamak plasma; Modelisation et commande d`un plasma de tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Bremond, S

    1995-10-18

    Vertically elongated tokamak plasmas, while attractive as regards Lawson criteria, are intrinsically instable. It is found that the open-loop instability dynamics is characterised by the relative value of two dimensionless parameters: the coefficient of inductive coupling between the vessel and the coils, and the coil damping efficiency on the plasma displacement relative to that of the vessel. Applications to Tore Supra -where the instability is due to the iron core attraction- and DIII-D are given. A counter-effect of the vessel, which temporarily reverses the effect of coil control on the plasma displacement, is seen when the inductive coupling is higher than the damping ratio. Precise control of the plasma boundary is necessary if plasma-wall interaction and/or coupling to heating antennas are to be monitored. A positional drift, of a few mm/s, which had been observed in the Tore Supra tokamak, is explained and corrected. A linear plasma shape response model is then derived from magnetohydrodynamic equilibrium calculation, and proved to be in good agreement with experimental data. An optimal control law is derived, which minimizes an integral quadratic criteria on tracking errors and energy expenditure. This scheme avoids compensating coil currents, and could render local plasma shaping more precise. (authors). 123 refs., 77 figs., 6 tabs., 4 annexes.

  11. Health Parameter Estimation with Second-Order Sliding Mode Observer for a Turbofan Engine

    Directory of Open Access Journals (Sweden)

    Xiaodong Chang

    2017-07-01

    Full Text Available In this paper the problem of health parameter estimation in an aero-engine is investigated by using an unknown input observer-based methodology, implemented by a second-order sliding mode observer (SOSMO. Unlike the conventional state estimator-based schemes, such as Kalman filters (KF and sliding mode observers (SMO, the proposed scheme uses a “reconstruction signal” to estimate health parameters modeled as artificial inputs, and is not only applicable to long-time health degradation, but reacts much quicker in handling abrupt fault cases. In view of the inevitable uncertainties in engine dynamics and modeling, a weighting matrix is created to minimize such effect on estimation by using the linear matrix inequalities (LMI. A big step toward uncertainty modeling is taken compared with our previous SMO-based work, in that uncertainties are considered in a more practical form. Moreover, to avoid chattering in sliding modes, the super-twisting algorithm (STA is employed in observer design. Various simulations are carried out, based on the comparisons between the KF-based scheme, the SMO-based scheme in our earlier research, and the proposed method. The results consistently demonstrate the capabilities and advantages of the proposed approach in health parameter estimation.

  12. Observations of unusual whistlers during daytime at Jammu

    Indian Academy of Sciences (India)

    1999-03-08

    spectra of these events is briefly presented. 1. Introduction. Whistler ... tude whistlers and the determination of various plasma parameters in .... (Date of whistler recording March 8, 1999). Total. Time of. Equatorial electron observation. Nose electron content NT hours. Dispersion frequency density. 10. 13 el/(cm. 2. Whistler.

  13. Rayleigh-Taylor-instability evolution in colliding-plasma-jet experiments with magnetic and viscous stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Colin Stuart [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States); Univ. of Washington, Seattle, WA (United States)

    2015-01-15

    The Rayleigh-Taylor instability causes mixing in plasmas throughout the universe, from micron-scale plasmas in inertial confinement fusion implosions to parsec-scale supernova remnants. The evolution of this interchange instability in a plasma is influenced by the presence of viscosity and magnetic fields, both of which have the potential to stabilize short-wavelength modes. Very few experimental observations of Rayleigh-Taylor growth in plasmas with stabilizing mechanisms are reported in the literature, and those that are reported are in sub-millimeter scale plasmas that are difficult to diagnose. Experimental observations in well-characterized plasmas are important for validation of computational models used to make design predictions for inertial confinement fusion efforts. This dissertation presents observations of instability growth during the interaction between a high Mach-number, initially un-magnetized plasma jet and a stagnated, magnetized plasma. A multi-frame fast camera captures Rayleigh-Taylor-instability growth while interferometry, spectroscopy, photodiode, and magnetic probe diagnostics are employed to estimate plasma parameters in the vicinity of the collision. As the instability grows, an evolution to longer mode wavelength is observed. Comparisons of experimental data with idealized magnetohydrodynamic simulations including a physical viscosity model suggest that the observed instability evolution is consistent with both magnetic and viscous stabilization. These data provide the opportunity to benchmark computational models used in astrophysics and fusion research.

  14. Determining cosmological parameters with the latest observational data

    International Nuclear Information System (INIS)

    Xia Junqing; Li Hong; Zhao Gongbo; Zhang Xinmin

    2008-01-01

    In this paper, we combine the latest observational data, including the WMAP five-year data (WMAP5), BOOMERanG, CBI, VSA, ACBAR, as well as the baryon acoustic oscillations (BAO) and type Ia supernovae (SN) ''union'' compilation (307 sample), and use the Markov Chain Monte Carlo method to determine the cosmological parameters, such as the equation of state (EoS) of dark energy, the curvature of the universe, the total neutrino mass, and the parameters associated with the power spectrum of primordial fluctuations. In a flat universe, we obtain the tight limit on the constant EoS of dark energy as w=-0.977±0.056(stat)±0.057(sys). For the dynamical dark energy models with the time evolving EoS parametrized as w de (a)=w 0 +w 1 (1-a), we find that the best-fit values are w 0 =-1.08 and w 1 =0.368, while the ΛCDM model remains a good fit to the current data. For the curvature of the universe Ω k , our results give -0.012 k de =-1. When considering the dynamics of dark energy, the flat universe is still a good fit to the current data, -0.015 k s ≥1 are excluded at more than 2σ confidence level. However, in the framework of dynamical dark energy models, the allowed region in the parameter space of (n s ,r) is enlarged significantly. Finally, we find no strong evidence for the large running of the spectral index.

  15. A study of single and binary ion plasma expansion into laboratory-generated plasma wakes

    Science.gov (United States)

    Wright, Kenneth Herbert, Jr.

    1988-01-01

    Plasma expansion into the wake of a large rectangular plate immersed in a collisionless, supersonic plasma was investigated in laboratory experiments. The experimental conditions address both single ion and binary ion plasma flows for the case of a body whose size is large in comparison with the Debye length, when the potential difference between the body and the plasma is relatively small. A new plasma source was developed to generate equi-velocity, binary ion plasma flows, which allows access to new parameter space that have previously been unavailable for laboratory studies. Specifically, the new parameters are the ionic mass ratio and the ionic component density ratio. In a series of experiments, a krypton-neon plasma is employed where the ambient density ratio of neon to krypton is varied more than an order of magnitude. The expansion in both the single ion and binary ion plasma cases is limited to early times, i.e., a few ion plasma periods, by the combination of plasma density, plasma drift speed, and vacuum chamber size, which prevented detailed comparison with self-similar theory.

  16. From stellar plasmas to laboratory plasmas: application to X and XUV opacity measurements

    International Nuclear Information System (INIS)

    Loisel, G.

    2011-01-01

    The general context of this thesis is the one of radiative properties of high energy density matter. Energy densities involved (>10 11 J/cm 3 ) implies that a large part of energy exchange goes through radiation-matter interactions. My studies deal with spectral opacity, a fundamental parameter for modelling stellar interiors and constitute a propitious observable to experimental tests of theoretical descriptions of hot and dense plasmas physics. Although the main application of my work is stellar plasmas it can be useful for plasma diagnostics in inertial confinement fusion. My work activities are centred on the experimental study of opacities of plasmas at local thermodynamic equilibrium for temperature conditions of a few tens eV (a few 100000 K) and a few mg/cm 3 in matter density. Plasmas are obtained in conditions as homogenous as possible using the radiative heating of a laser-irradiated cavity. Heating is provided through a laser beam of high energy (100-300 J) and with relatively long pulse duration of a few nanosecond. For such measurements we could benefit from the LULI lasers configuration coupling the nanosecond beam with a picosecond one used to perform on a short duration the measurement of the plasma transmission. The use of short pulse laser to produce a short time radiography beam was a first achievement for this kind of experience. In the spectral range of keV photons, absorbing transitions 2p-3d or 3d-4f of elements of moderate or high atomic number have been probed. They present absorption structures which shape results mainly of the competition between spin-orbit splitting and statistical broadening effects. It appeared that this competition depends strongly on the atomic number Z. Thus for similar plasma parameters we explored opacities of Iron, Nickel, Copper and Germanium (Z around 30) in a first series of measurement and the one of Barium, Samarium and Gadolinium (Z around 60) in a second campaign

  17. Density gradients in the solar plasma observed by interplanetary scintillation

    International Nuclear Information System (INIS)

    Gapper, G.R.; Hewish, A.

    1981-01-01

    A new technique is described which overcomes the limitation set by Fresnel filtering in previous IPS studies of the small-scale density irregularities in the solar plasma. Phase gradients introduced by irregularities larger than the Fresnel limit cause transverse displacements of the small-scale scintillation pattern. In the presence of the solar wind, such refraction effects may be revealed by simultaneous measurements of intensity scintillation at two radio frequencies. Observations show that the structure corresponding to temporal frequencies approximately 0.02 Hz is in agreement with an extrapolation of the Kolmogorov spectrum derived from spacecraft data at lower frequencies. (author)

  18. Plasma sheath in non-Maxwellian plasma

    International Nuclear Information System (INIS)

    Shimizu, Takuo; Horigome, Takashi

    1992-01-01

    Reviewing many theoretical and experimental works on the electron-energy distributions (EEDF) of various plasmas, we point out that many plasmas have EEDF of non-Maxwellian in shape. Therefore, the recent treatment of plasma sheath using the Maxwell-Boltzmann distribution approximation should be improved. To do this, we have adopted Rutcher's standard distribution as a generalized form in place of the traditional Maxwellian, and found that the minimum energy of ions entering the sheath edge (Bohm's criterion) varies largely, and have also shown the variation of Debye length with the shape of EEDF. The length is the most important parameter to proceed with more detailed analysis on plasma-sheaths, and also to control them in the future. (author)

  19. Evidence of Mixed-mode oscillations and Farey arithmetic in double plasma system in presence of fireball

    Science.gov (United States)

    Mitra, Vramori; Sarma, Bornali; Sarma, Arun

    2017-10-01

    Plasma fireballs are luminous glowing region formed around a positively biased electrode. The present work reports the observation of mix mode oscillation (MMO) in the dynamics of plasma oscillations that are excited in the presence of fireball in a double plasma device. Source voltage and applied electrode voltage are considered as the controlling parameters for the experiment. Many sequences of distinct multi peaked periodic states reflects the presence of MMO with the variation of control parameter. The sequences of states with two patterns are characterized well by Farey arithmetic, which provides rational approximations of irrational numbers. These states can be characterized by a firing number, the ratio of the number of small amplitude oscillations to the total number of oscillations per period. The dynamical transition in plasma fireball is also demonstrated by spectral analysis, recurrence quantification analysis (RQA) and by statistical measures viz., skewness and kurtosis. The mix mode phenomenon observed in the experiment is consistent with a model that describes the dynamics of ionization instabilities.

  20. Modulation of plasma N-acylethanolamine levels and physiological parameters by dietary fatty acid composition in humans.

    Science.gov (United States)

    Jones, Peter J H; Lin, Lin; Gillingham, Leah G; Yang, Haifeng; Omar, Jaclyn M

    2014-12-01

    N-Acylethanolamines (NAEs) are endogenous lipid-signaling molecules involved in satiety and energetics; however, how diet impacts circulating NAE concentrations and their downstream metabolic actions in humans remains unknown. Objectives were to examine effects of diets enriched with high-oleic canola oil (HOCO) or HOCO blended with flaxseed oil (FXCO), compared with a Western diet (WD), on plasma NAE levels and the association with energy expenditure and substrate oxidation. Using a randomized controlled crossover design, 36 hypercholesterolemic participants consumed three isoenergetic diets for 28 days, each containing 36% energy from fat, of which 70% was HOCO, FXCO, or WD. Ultra-performance liquid chromatography-MS/MS was used to measure plasma NAE levels and indirect calorimetry to assess energy expenditure and substrate oxidation. After 28 days, compared with WD, plasma oleoylethanolamide (OEA) and alpha-linolenoyl ethanolamide (ALEA) levels were significantly increased in response to HOCO and FXCO (P = 0.002, P < 0.001), respectively. Correlation analysis demonstrated an inverse association between plasma OEA levels and percent body fat (r = -0.21, P = 0.04), and a positive association was observed between the plasma arachidonoyl ethanolamide (AEA)/OEA ratio and android:gynoid fat (r = 0.23, P = 0.02), respectively. Results suggest that plasma NAE levels are upregulated via their dietary lipid substrates and may modulate regional and total fat mass through lipid-signaling mechanisms. Copyright © 2014 by the American Society for Biochemistry and Molecular Biology, Inc.

  1. Laboratory simulation of the formation of an ionospheric depletion using Keda Space Plasma EXperiment (KSPEX

    Directory of Open Access Journals (Sweden)

    Pengcheng Yu

    2017-10-01

    Full Text Available In the work, the formation of an ionospheric depletion was simulated in a controlled laboratory plasma. The experiment was performed by releasing chemical substance sulfur hexafluoride (SF6 into the pure argon discharge plasma. Results indicate that the plasma parameters change significantly after release of chemicals. The electron density is nearly depleted due to the sulfur hexafluoride-electron attachment reaction; and the electron temperature and space potential experience an increase due to the decrease of the electron density. Compared to the traditional active release experiments, the laboratory scheme can be more efficient, high repetition rate and simpler measurement of the varying plasma parameter after chemical releasing. Therefore, it can effective building the bridge between the theoretical work and real space observation.

  2. Current sustaining by RF travelling field in a collisional toroidal plasma

    International Nuclear Information System (INIS)

    Fukuda, Masaji; Matsuura, Kiyokata

    1978-01-01

    The relation between the current generated by RF travelling field and the absorbed power is studied in a collisional toroidal plasma, parameters being phase velocity and filling gap pressure or electron collision frequency. It is observed at a low magnetic field that the current is proportional to the plasma conductivity and an effective electromotive force, which is a new concept introduced on the basis of fluid model; the electromotive force is proportional to the absorbed RF power and inversely proportional to the plasma density and the phase velocity of the travelling field. (author)

  3. Current sustaining by RF travelling field in a collisional toroidal plasma

    International Nuclear Information System (INIS)

    Fukuda, Masaji; Matsuura, Kiyokata.

    1977-06-01

    The relation between the current generation by RF travelling field and the accompanied power absorption is studied in a collisional toroidal plasma, parameters being phase velocity and filling gas pressure or electron collision frequency. It is observed at a low magnetic field that the current is proportional to the plasma conductivity and an effective electromotive force, which is a new concept introduced on the basis of fluid model; the electromotive force is proportional to the absorbed RF power and inversely proportional to the plasma density and the phase velocity of the travelling field. (auth.)

  4. X-ray laser studies using plasmas created by optical field ionization

    International Nuclear Information System (INIS)

    Krushelnick, K.M.; Tighe, W.; Suckewer, S.

    1995-01-01

    X-ray laser experiments involving the creation of fast recombining plasmas by optical field ionization of preformed targets were conducted. A nonlinear increase in the intensity of the 13.5nm Lyman-α line in Li III with the length of the target plasma was observed but only for distances less than the laser confocal parameter and for low plasma electron temperatures. Multiphoton pumping of resonant atomic transitions was also examined and the process of multiphoton ionization of FIII was found to be more probable than multiphoton excitation

  5. Geotail observations of plasma sheet ion composition over 16 years: On variations of average plasma ion mass and O+ triggering substorm model

    Science.gov (United States)

    Nosé, M.; Ieda, A.; Christon, S. P.

    2009-07-01

    We examined long-term variations of ion composition in the plasma sheet, using energetic (9.4-212.1 keV/e) ion flux data obtained by the suprathermal ion composition spectrometer (STICS) sensor of the energetic particle and ion composition (EPIC) instrument on board the Geotail spacecraft. EPIC/STICS observations are available from 17 October 1992 for more than 16 years, covering the declining phase of solar cycle 22, all of solar cycle 23, and the early phase of solar cycle 24. This unprecedented long-term data set revealed that (1) the He+/H+ and O+/H+ flux ratios in the plasma sheet were dependent on the F10.7 index; (2) the F10.7 index dependence is stronger for O+/H+ than He+/H+; (3) the O+/H+ flux ratio is also weakly correlated with the ΣKp index; and (4) the He2+/H+ flux ratio in the plasma sheet appeared to show no long-term trend. From these results, we derived empirical equations related to plasma sheet ion composition and the F10.7 index and estimated that the average plasma ion mass changes from ˜1.1 amu during solar minimum to ˜2.8 amu during solar maximum. In such a case, the Alfvén velocity during solar maximum decreases to ˜60% of the solar minimum value. Thus, physical processes in the plasma sheet are considered to be much different between solar minimum and solar maximum. We also compared long-term variation of the plasma sheet ion composition with that of the substorm occurrence rate, which is evaluated by the number of Pi2 pulsations. No correlation or negative correlation was found between them. This result contradicts the O+ triggering substorm model, in which heavy ions in the plasma sheet increase the growth rate of the linear ion tearing mode and play an important role in localization and initiation of substorms. In contrast, O+ ions in the plasma sheet may prevent occurrence of substorms.

  6. Beta limit of resistive plasma in Torsatron / Heliotron

    International Nuclear Information System (INIS)

    Itoh, K.; Ichiguchi, K.; Itoh, S.I.

    1992-02-01

    Stability against the interchange mode in the Torsatron / Heliotron device is investigated, taking into account the effects of the resistivity, current diffusivity, ion viscosity and thermal diffusivity. Critical beta for the low-mode-number stability is found at the finite beta value. For the range of plasma parameters of the present experiments, the resistive mode and current diffusive mode set comparable critical beta values, which are consistent with experimental observations. In future high temperature plasmas, the current diffusive mode determines the stability limit for the global mode. (author)

  7. An empirical model of the topside plasma density around 600 km based on ROCSAT-1 and Hinotori observations

    Science.gov (United States)

    Huang, He; Chen, Yiding; Liu, Libo; Le, Huijun; Wan, Weixing

    2015-05-01

    It is an urgent task to improve the ability of ionospheric empirical models to more precisely reproduce the plasma density variations in the topside ionosphere. Based on the Republic of China Satellite 1 (ROCSAT-1) observations, we developed a new empirical model of topside plasma density around 600 km under relatively quiet geomagnetic conditions. The model reproduces the ROCSAT-1 plasma density observations with a root-mean-square-error of 0.125 in units of lg(Ni(cm-3)) and reasonably describes the temporal and spatial variations of plasma density at altitudes in the range from 550 to 660 km. The model results are also in good agreement with observations from Hinotori, Coupled Ion-Neutral Dynamics Investigations/Communications/Navigation Outage Forecasting System satellites and the incoherent scatter radar at Arecibo. Further, we combined ROCSAT-1 and Hinotori data to improve the ROCSAT-1 model and built a new model (R&H model) after the consistency between the two data sets had been confirmed with the original ROCSAT-1 model. In particular, we studied the solar activity dependence of topside plasma density at a fixed altitude by R&H model and find that its feature slightly differs from the case when the orbit altitude evolution is ignored. In addition, the R&H model shows the merging of the two crests of equatorial ionization anomaly above the F2 peak, while the IRI_Nq topside option always produces two separate crests in this range of altitudes.

  8. ICRF-enhanced plasma potentials in the SOL of Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Ochoukov, R.; Whyte, D. G.; Brunner, D.; LaBombard, B.; Lipschultz, B.; Terry, J. L.; Wukitch, S. J. [PSFC MIT, NW17, 175 Albany Street, Cambridge, MA 02139 (United States); D' Ippolito, D. A.; Myra, J. R. [Lodestar Research Corporation, 2400 Central Avenue, Boulder, Colorado 80301 (United States)

    2014-02-12

    We performed an extensive survey of the plasma potential in the scrape-off layer (SOL) of Ion Cyclotron Range-of Frequencies (ICRF)-heated discharges on Alcator C-Mod. Our results show that plasma potentials are enhanced in the presence of ICRF power and plasma potential values of >100 V are often observed. Such potentials are high enough to induce sputtering of high-Z molybdenum (Mo) plasma facing components by deuterium ions on C-Mod. For comparison, the plasma potential in Ohmic discharges is typically less than 10 V, well below the threshold needed to induce Mo sputtering by deuterium ions. ICRF-enhanced plasma potentials are observed in the SOL regions that both magnetically map and do not map to active ICRF antennas. Regions that magnetically map to active ICRF antennas are accessible to slow waves directly launched by the antennas and these regions experience plasma potential enhancement that is partially consistent with the slow wave rectification mechanism. One of the most defining features of the slow wave rectification is a threshold appearance of significant plasma potentials (>100 V) when the dimensionless rectification parameter Λ{sub −o} is above unity and this trend is observed experimentally. We also observe ICRF-enhanced plasma potentials >100 V in regions that do not magnetically map to the active antennas and, hence, are not accessible for slow waves launched directly by the active antennas. However, unabsorbed fast waves can reach these regions. The general trend that we observe in these 'un-mapped' regions is that the plasma potential scales with the strength of the local RF wave fields with the fast wave polarization and the highest plasma potentials are observed in discharges with the highest levels of unabsorbed ICRF power. Similarly, we find that core Mo levels scale with the level of unabsorbed ICRF power suggesting a link between plasma potentials in the SOL and the strength of the impurity source.

  9. Multi electron species and shielding potentials in plasmas

    International Nuclear Information System (INIS)

    Khan, Arroj A.; Murtaza, G.; Rasheed, A.; Jamil, M.

    2012-01-01

    The phenomenon of Debye shielding is investigated in electron ion plasmas using the approach of two temperature electrons. We get different profiles of potential for different parameters and observe that the potentials fall very slowly than the standard Coulomb and Debye potentials. The importance of work is pointed out in the introduction.

  10. Online plasma calculator

    Science.gov (United States)

    Wisniewski, H.; Gourdain, P.-A.

    2017-10-01

    APOLLO is an online, Linux based plasma calculator. Users can input variables that correspond to their specific plasma, such as ion and electron densities, temperatures, and external magnetic fields. The system is based on a webserver where a FastCGI protocol computes key plasma parameters including frequencies, lengths, velocities, and dimensionless numbers. FastCGI was chosen to overcome security problems caused by JAVA-based plugins. The FastCGI also speeds up calculations over PHP based systems. APOLLO is built upon the WT library, which turns any web browser into a versatile, fast graphic user interface. All values with units are expressed in SI units except temperature, which is in electron-volts. SI units were chosen over cgs units because of the gradual shift to using SI units within the plasma community. APOLLO is intended to be a fast calculator that also provides the user with the proper equations used to calculate the plasma parameters. This system is intended to be used by undergraduates taking plasma courses as well as graduate students and researchers who need a quick reference calculation.

  11. Some necessary parameters for a critical velocity interaction between the ionospheric plasma and a xenon cloud

    International Nuclear Information System (INIS)

    Axnaes, I.

    1979-12-01

    The conditions for an experiment to study the critical ionization velocity effect in the interaction between a Xenon cloud, released from a satellite, and the ionospheric plasma are investigated. The model used is based on the assumption that there exists an effective process that transfers the energy, that is available in the relative motion, to the electrons. Some necessary conditions to obtain significant heating or deceleration of the plasma penetrating the cloud are calculated. The conditions are mainly given by the energy available in the relative motion and the rates of the different binary collision processes involved. As the released gas cloud expands the possibilities for a critical velocity interaction will exist only within a certain range of cloud radii. It is shown that the charge transfer collision cross section between the ionospheric ions and the cloud atoms is an important parameter and that Xenon is a very suitable gas in that respect. (author)

  12. CALIBRATIONS OF ATMOSPHERIC PARAMETERS OBTAINED FROM THE FIRST YEAR OF SDSS-III APOGEE OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Mészáros, Sz.; Allende Prieto, C. [Instituto de Astrofísica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain); Holtzman, J. [New Mexico State University, Las Cruces, NM 88003 (United States); García Pérez, A. E.; Chojnowski, S. D.; Hearty, F. R.; Majewski, S. R. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States); Schiavon, R. P. [Astrophysics Research Institute, Liverpool John Moores University, Egerton Wharf, Birkenhead, Wirral CH41 1LD (United Kingdom); Basu, S. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Bizyaev, D. [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349-0059 (United States); Chaplin, W. J.; Elsworth, Y. [University of Birmingham, School of Physics and Astronomy, Edgbaston, Birmingham B15 2TT (United Kingdom); Cunha, K. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Epstein, C.; Johnson, J. A. [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States); Frinchaboy, P. M. [Texas Christian University, Fort Worth, TX 76129 (United States); García, R. A. [Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, IRFU/SAp, Centre de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Hekker, S. [Astronomical Institute ' ' Anton Pannekoek' ' , University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Kallinger, T. [Institute for Astronomy, University of Vienna, Türkenschanzstrasse 17, A-1180 Vienna (Austria); Koesterke, L. [Texas Advanced Computing Center, University of Texas, Austin, TX 78759 (United States); and others

    2013-11-01

    The Sloan Digital Sky Survey III (SDSS-III) Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a three-year survey that is collecting 10{sup 5} high-resolution spectra in the near-IR across multiple Galactic populations. To derive stellar parameters and chemical compositions from this massive data set, the APOGEE Stellar Parameters and Chemical Abundances Pipeline (ASPCAP) has been developed. Here, we describe empirical calibrations of stellar parameters presented in the first SDSS-III APOGEE data release (DR10). These calibrations were enabled by observations of 559 stars in 20 globular and open clusters. The cluster observations were supplemented by observations of stars in NASA's Kepler field that have well determined surface gravities from asteroseismic analysis. We discuss the accuracy and precision of the derived stellar parameters, considering especially effective temperature, surface gravity, and metallicity; we also briefly discuss the derived results for the abundances of the α-elements, carbon, and nitrogen. Overall, we find that ASPCAP achieves reasonably accurate results for temperature and metallicity, but suffers from systematic errors in surface gravity. We derive calibration relations that bring the raw ASPCAP results into better agreement with independently determined stellar parameters. The internal scatter of ASPCAP parameters within clusters suggests that metallicities are measured with a precision better than 0.1 dex, effective temperatures better than 150 K, and surface gravities better than 0.2 dex. The understanding provided by the clusters and Kepler giants on the current accuracy and precision will be invaluable for future improvements of the pipeline.

  13. MHD model of magnetosheath flow: comparison with AMPTE/IRM observations on 24 October, 1985

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    1998-05-01

    Full Text Available We compare numerical results obtained from a steady-state MHD model of solar wind flow past the terrestrial magnetosphere with documented observations made by the AMPTE/IRM spacecraft on 24 October, 1985, during an inbound crossing of the magnetosheath. Observations indicate that steady conditions prevailed during this about 4 hour-long crossing. The magnetic shear at spacecraft entry into the magnetosphere was 15°. A steady density decrease and a concomitant magnetic field pile-up were observed during the 40 min interval just preceding the magnetopause crossing. In this plasma depletion layer (1 the plasma beta dropped to values below unity; (2 the flow speed tangential to the magnetopause was enhanced; and (3 the local magnetic field and velocity vectors became increasingly more orthogonal to each other as the magnetopause was approached (Phan et al., 1994. We model parameter variations along a spacecraft orbit approximating that of AMPTE/IRM, which was at slightly southern GSE latitudes and about 1.5 h post-noon Local Time. We model the magnetopause as a tangential discontinuity, as suggested by the observations, and take as input solar wind parameters those measured by AMPTE/IRM just prior to its bow shock crossing. We find that computed field and plasma profiles across the magnetosheath and plasma depletion layer match all observations closely. Theoretical predictions on stagnation line flow near this low-shear magnetopause are confirmed by the experimental findings. Our theory does not give, and the data on this pass do not show, any localized density enhancements in the inner magnetosheath region just outside the plasma depletion layer.Key words. Steady-state magnetosheath · Plasma depletion layer · Stagnation line flow

  14. Observation of helical structure in a low energy plasma focus pinch

    International Nuclear Information System (INIS)

    Rout, R.K.; Shyam, A.

    1989-01-01

    Helical structure and hot spots were observed in a Mather-type plasma focus operated at 3 KJ of bank energy. The experiments were carried out with the help of a fast optical framing camera and two X-ray pin-hole cameras with different filters. It was observed that initially a conical pinch (with base diameter of 6 mm and length of 14 mm) with temperature of ≅ 10 2 eV was formed. This pinch disintegrated after ≅ 50 ns by a single lobe sausage instability into a central high temperature (≅ 10 3 eV) filament of 1 mm diameter and 8 mm length containing a high emissivity helical structure. This helix is probably responsible for generation of axial magnetic field and relaxation of the focus pinch. Hot spots of high X-ray intensity and temperature (≅ 10 3 eV) were also observed much beyond the filament region. (author)

  15. Normal-mode Magnetoseismology as a Virtual Instrument for the Plasma Mass Density in the Inner Magneotsphere: MMS Observations during Magnetic Storms

    Science.gov (United States)

    Chi, P. J.; Takahashi, K.; Denton, R. E.

    2017-12-01

    Previous studies have demonstrated that the electric and magnetic field measurements on closed field lines can detect harmonic frequencies of field line resonance (FLR) and infer the plasma mass density distribution in the inner magnetosphere. This normal-mode magnetoseismology technique can act as a virtual instrument for spacecraft with a magnetometer and/or an electric field instrument, and it can convert the electromagnetic measurements to knowledge about the plasma mass, of which the dominant low-energy core is difficult to detect directly due to the spacecraft potential. The additional measurement of the upper hybrid frequency by the plasma wave instrument can well constrain the oxygen content in the plasma. In this study, we use field line resonance (FLR) frequencies observed by the Magnetospheric Multiscale (MMS) satellites to estimate the plasma mass density during magnetic storms. At FLR frequencies, the phase difference between the azimuthal magnetic perturbation and the radial electric perturbation is approximately ±90°, which is consistent with the characteristic of standing waves. During the magnetic storm in October 2015, the FLR observations indicate a clear enhancement in the plasma mass density on the first day of the recovery phase, but the added plasma was quickly removed on the following day. We will compare with the FLR observations by other operating satellites such as the Van Allen Probes and GOES to examine the spatial variations of the plasma mass density in the magnetosphere. Also discussed are how the spacing in harmonic frequencies can infer the distribution of plasma mass density along the field line as well as its implications.

  16. Electrostatic fluctuations measured in low temperature helical plasmas with low collisionality

    International Nuclear Information System (INIS)

    Takeuchi, M.; Ikeda, R.; Ito, T.; Toi, K.; Suzuki, C.; Matsunaga, G.

    2004-01-01

    Electrostatic fluctuations have been measured by Langmuir probes from edge to core plasma region in low temperature helical plasmas which are produced by 2.45 GHz microwaves at very low field less than 0.1 T. The principal dimensionless parameters of the plasmas, that is, the normalized electron-ion collision frequency ν ei , and averaged plasma β φ and others are in the same range of them in high temperature plasmas, except the normalized gyro radius ρ s . The data on fluctuation characteristics from the dimensionally similar low temperature plasmas may give an important insight into the understanding of turbulent transport in high temperature plasmas. Dependences of fluctuation amplitudes on the radial electric field shear, ρ s and ν ei are investigated. Electrostatic fluctuations propagating in electron-diamagnetic drift direction have been observed in the plasma edge region and in ion-diamagnetic drift direction in the plasma core region. (authors)

  17. Magnetized relativistic electron-ion plasma expansion

    Science.gov (United States)

    Benkhelifa, El-Amine; Djebli, Mourad

    2016-03-01

    The dynamics of relativistic laser-produced plasma expansion across a transverse magnetic field is investigated. Based on a one dimensional two-fluid model that includes pressure, enthalpy, and rest mass energy, the expansion is studied in the limit of λD (Debye length) ≤RL (Larmor radius) for magnetized electrons and ions. Numerical investigation conducted for a quasi-neutral plasma showed that the σ parameter describing the initial plasma magnetization, and the plasma β parameter, which is the ratio of kinetic to magnetic pressure are the key parameters governing the expansion dynamics. For σ ≪ 1, ion's front shows oscillations associated to the break-down of quasi-neutrality. This is due to the strong constraining effect and confinement of the magnetic field, which acts as a retarding medium slowing the plasma expansion.

  18. Determination of reference ranges for full blood count parameters in neonatal cord plasma in Hilla, Babil, Iraq

    Science.gov (United States)

    Al-Marzoki, Jasim M; Al-Maaroof, Zainab W; Kadhum, Ali H

    2012-01-01

    Background The health of an individual is known to vary in different countries, in the same country at different times, and in the same individuals at different ages. This means that the condition of individuals must be related to or compared with reference data. Determination of a reference range for the healthy term newborn is clinically important in terms of various complete blood count parameters. The purpose of this study was to establish a local reference range for full blood count parameters in neonatal cord plasma in Hilla, Babil, Iraq. Methods A total of 220 mothers and their neonates were enrolled in this cross-sectional study from February 2011 to January 2012. Maternal inclusion criteria were age 15–45 years, an uneventful pregnancy, and hemoglobin ≥ 10 g. Neonatal inclusion criteria were full term (37–42 weeks) and normal birth weight. The umbilical cord was immediately clamped after delivery of the baby; 3 mL of cord blood was then taken from the umbilical vein and collected in a tube containing ethylenediamine tetra-acetic acid, its plasma was analyzed for full blood count parameters by standard Coulter gram, and the differential leukocyte count was done manually. Results Mean neonatal hemoglobin was 13.88 ± 1.34 (range 11–17.3) g/dL and mean white cell count was 10.12 ± 2.8 (range 3.1–21.6) × 109/L. Mean platelet count was 267.63 ± 60.62 (range 152–472) × 109/L. No significant differences in red cell, white cell, or platelet counts were found between males and females, except for neutrophil count. The current study shows lower levels of hemoglobin, white cells, and red cells compared with other studies, and there is agreement with some studies and disagreement with others concerning platelet count. Conclusion Most results in the current study were within the reference range. The hematological reference values for Iraqi neonatal cord plasma need to be confirmed by larger numbers of blood samples and by collecting samples from

  19. MMS Observations of Vorticity Near Sites of Magnetic Reconnection

    Science.gov (United States)

    Paterson, W. R.; Giles, B. L.; Avanov, L. A.; Boardsen, S. A.; Dorelli, J.; Gershman, D. J.; Mackler, D. A.; Moore, T. E.; Pollock, C. J.; Schiff, C.; Shuster, J. R.; Viñas, A. F.; Russell, C. T.; Strangeway, R. J.; Burch, J. L.; Torbert, R. B.

    2017-12-01

    With highly capable plasma instruments on four spacecraft flown in tetrahedral formation, it is possible for MMS investigators to approximate spatial derivatives of the plasma parameters observed. Here, we examine vorticity of the electron and ion components of the plasma computed from the curl of velocity as measured by the Fast Plasma Investigation (FPI). Vorticity of magnetospheric plasma has not previously been studied on scales of tens-of-km to less than 10 km, which are the typical inter-spacecraft separations for MMS. Nor has it been explored on time scales of 30 ms for electrons and 150 ms for ions, which are the burst data rates for the FPI spectrometers. Review of observations from the magnetopause and magnetotail phases of the mission finds increases in vorticity associated with near encounters with the electron diffusion region, with nearby regions of measurable current, and with elevated electron and ion temperatures. These are suggestive of a possible role for turbulence in magnetic reconnection. In this presentation we provide an assessment of the quality of these measurements and discuss their potential significance.

  20. Non-linear collective phenomena in dusty plasmas

    International Nuclear Information System (INIS)

    Tsytovich, V N; Morfill, G E

    2004-01-01

    Dusty plasmas are unusual states of matter where the interactions between the dust grains can be collective and are not a sum of all pair particle interactions. This state of matter is appropriate to form non-linear dissipative collective self-organized structures. It is found that the potential around the grains can be over-screened leading to a new phenomenon-collective attraction of pairs of large charge grains of equal sign. The grain clouds can self-contract and their collapse is terminated at distances where the interaction becomes repulsive. The homogeneous dusty plasma distribution is universally unstable to form structures. The potential of the collective attraction is proportional to the square of the dimensionless parameter P = n d Z d /n i , where n d and n i are the average dust and ion densities, respectively, and Z d is the dust charge in units of electron charge. The collective attraction is determined by finite grain size and by the presence of absorption of plasma flux on grains. The physics of attraction is related to the space charge accumulation caused by collective flux disturbances. The collective attraction operates for systems with size larger than the mean free path for ion-dust absorption, the condition met in many existing low temperature dusty plasma experiments, in edge plasmas of fusion devices and in space dusty plasmas. The collective attraction exceeds the previously known non-collective attraction such as shadow attraction or wake attraction. The collective attraction can be responsible for pairing of dust grains (this process is completely classical in contrast to the known pairing in superconductivity) and can serve as the main process for the formation of more complicated dust complexes up to dust-plasma crystals. The equilibrium structures formed by collective attraction have universal properties and can exist in a limited domain of parameters (similar to the equilibrium balance known for stars). The balance conditions for

  1. Study of plasma-material surface interaction using langmuir probe technique during plasma treatment

    International Nuclear Information System (INIS)

    Saloum, S.; Akel, M.

    2012-01-01

    In this study, we tried to understand the plasma-surface interactions by using Langmuir probes. Two different types of plasmas were studied, the first is the electropositive plasma in Argon and the second is the electronegative plasma in Sulfur Hexafluoride. In the first type, the effects of Argon gas pressure, the injection of Helium in the remote zone and the substrate bias on the measurements of the Electron Energy Probability Function (EEPF) and on the plasma parameters (electron density (n e ), effective electron temperature (T e ff), plasma potential (V p ) and floating potential (V f )) have been investigated. The obtained EEPFs and plasma parameters have been used to control two remote plasma processes. The first is the remote Plasma Enhanced Chemical Vapor Deposition (PE-CVD) of thin films, on silicon wafers, from Hexamethyldisiloxane (HMDSO) precursor diluted in the remote Ar-He plasma. The second is the pure Argon remote plasma treatment of polymethylmethacrylate (PMMA) polymer surface. In the second type, the plasma diagnostics were performed in the remote zone as a function of SF 6 flow rate, where relative concentrations of fluorine atoms were measured using actinometry optical emission spectroscopy; electron density, electron temperature and plasma potential were determined using single cylindrical Langmuir probe, positive ion flux and negative ion fraction were determined using an planar probe. The silicon etching process in SF 6 plasma was studied. (author)

  2. Study of plasma-material surface interaction using Langmuir probe technique during plasma treatment

    International Nuclear Information System (INIS)

    Saloum, S.; Akel, M.

    2009-06-01

    In this study, we tried to understand the plasma-surface interactions by using Langmuir probes. Two different types of plasmas were studied, the first is the electropositive plasma in Argon and the second is the electronegative plasma in Sulfur Hexafluoride. In the first type, the effects of Argon gas pressure, the injection of Helium in the remote zone and the substrate bias on the measurements of the Electron Energy Probability Function (EEPF) and on the plasma parameters (electron density (n e ), effective electron temperature (T e ff), plasma potential (V p ) and floating potential (V f )) have been investigated. The obtained EEPFs and plasma parameters have been used to control two remote plasma processes. The first is the remote Plasma Enhanced Chemical Vapor Deposition (PE-CVD) of thin films, on silicon wafers, from Hexamethyldisoloxane (HMDSO) precursor diluted in the remote Ar-He plasma. The second is the pure Argon remote plasma treatment of polymethylmethacrylate (PMMA) polymer surface. In the second type, the plasma diagnostics were performed in the remote zone as a function of SF 6 flow rate, where relative concentrations of fluorine atoms were measured using actinometry optical emission spectroscopy; electron density, electron temperature and plasma potential were determined using single cylindrical Langmuir probe, positive ion flux and negative ion fraction were determined using an planar probe. The silicon etching process in SF 6 plasma was studied. (author)

  3. Experimental observation of nonlinear behaviour in a helium plasma discharge in the presence of a nonuniform magnetic field

    International Nuclear Information System (INIS)

    Toma, M.; Sanduloviciu, M.

    1994-01-01

    The nonlinear behaviour in an electrical discharge plasma due to the action of an external nonuniform magnetic field is presented. The discharge geometry and the magnetic field configuration ('inverse' cylindrical magnetron discharge) were so chosen that there is a possibility to control the net electron flux in a certain region of a positive electrode. The plasma discharge nonlinearity manifested in the profile of the current-voltage, current-magnetic field and current-gas pressure characteristics by the appearance of the anomalous negative resistance, in the bistability and hysteresis and also in the periodical and chaotic variation of the discharge current. The profile of the current variation vs control discharge parameters was related to the appearance of a space charge structure in the shape of nearly spherical bulges, delimited from the surrounding plasma by a double layer. (Author)

  4. Magnetic tearing in plasma focus

    International Nuclear Information System (INIS)

    Sharkawy, W.

    1994-01-01

    A plasma focus device used is Mather type filled with hydrogen gas at pressure between 0.1 and 1 torr. When connected to a large capacitor ≤10 KV a discharge is started with peak current 100 KA. Under the influence of the radial electric field E r , due to the potential between electrodes, and B φ the plasma will drift in the axial direction with velocity cE r /B φ . An induced axial magnetic field B z has been detected which due to sheath velocity. A propagation of magnetosonic wave has been observed with velocity ≅10 3 m sec -1 . Such a wave might be excited when the magnetic pressure is much greater than the plasma kinetic pressure B 2 /8π>nKT. Assuming (MHD) to be stable, Tearing model was driven which generally has smaller growth rates than (MHD) modes. Using the designed theoretical model and the plasma parameters the electron energy dΦ/dt=Ba 2 /τ R was calculated to be 2.22 KeV, which is comparable with that detected from X-ray measurements. (author)

  5. Correlation of Seminal Plasma Total Antioxidant Capacity and Malondialdehyde Levels With Sperm Parameters in Men With Idiopathic Infertility

    Directory of Open Access Journals (Sweden)

    Fazeli

    2016-01-01

    Full Text Available Background Oxidative stress is the result of an imbalance between the production and scavenging of reactive oxygen species (ROS. Recently, oxidative stress has been introduced as a major cause of male infertility. Objectives The aim of the present study was to determine the correlation between total antioxidant capacity (TAC and malondialdehyde (MDA as markers of oxidative stress in relation to idiopathic male infertility and sperm parameters. Patients and Methods This case control study was conducted using 35 men with idiopathic infertility and 34 men with proven fertility. Seminal plasma TAC and MDA were measured by ferric reducing ability of plasma (FRAP and thiobarbituric acid (TBA reaction methods, respectively. Results Seminal TAC levels were significantly lower and seminal MDA levels were significantly higher in men with idiopathic infertility than in fertile men (P < 0.0001 and P = 0.004, respectively. A positive correlation was shown between sperm motility, sperm morphology, and TAC levels in men with idiopathic infertility (P = 0.002 and P = 0.002, respectively. In addition, there was a correlation between sperm motility and TAC levels in fertile men (P = 0.005. There was no correlation between sperm count and TAC levels in either men with idiopathic infertility or in fertile men. Negative correlations were observed between MDA levels and sperm motility, morphology, and sperm count only in men with idiopathic infertility (P = 0.003, P = 0.001, and P = 0.006, respectively. Conclusions Our results show that oxidative stress could play an important role in male infertility as well as in sperm motility and sperm morphology.

  6. High-temperature plasma physics

    International Nuclear Information System (INIS)

    Furth, H.P.

    1988-03-01

    Both magnetic and inertial confinement research are entering the plasma parameter range of fusion reactor interest. This paper reviews the individual and common technical problems of these two approaches to the generation of thermonuclear plasmas, and describes some related applications of high-temperature plasma physics

  7. Dependence of polar effect on parameters of coaxial plasma-erosive switches

    International Nuclear Information System (INIS)

    Bystritskij, V.M.; Ivanov, I.B.; Krasik, Ya.E.; Ryzhakin, N.N.; Sinebryukhov, A.A.; Tolmacheva, V.G.

    1988-01-01

    The results of experimental investigations and numerical simulation of the polar effect in a coaxial plasma-erosive switch (PES) established in a circuit of a strong-current nanosecond accelerator are presented. PES characteristics (energy losses, impedance, rate of its increase, etc.) are investigated depending on mutual direction of accelerator current and plasma flow as well as on the cathode radius in the PES region. It is experimentally shown that the magnetic fields near the cathode determined by this electrode radius influences mainly on PES characteristics. Mutual direction of accelerator current and plasma flow is the second significance factor influencing on PES characteristics. The optimal mode of PES operation is realized when providing the less with respect to the positive electrode, cathode radius and coinciding in direction accelerator current and plasma flow. Numerical simulation of dynamic processes in coaxial PES for different ratios of cathode and anode radii and mutual directions of accelerator current and plasma flow gives qualitative agreement with the experimental results

  8. Compound sawtooth study in ohmically heated TFTR plasmas

    International Nuclear Information System (INIS)

    Yamada, H.; McGuire, K.; Colchin, D.

    1985-09-01

    Compound sawtooth activity has been observed in ohmically heated, high current, high density TFTR plasmas. Commonly called ''double sawteeth,'' such sequences consist of a repetitive series of subordinate relaxations followed by a main relaxation with a different inversion radius. The period of such compound sawteeth can be as long as 100 msec. In other cases, however, no compound sawteeth or bursts of them can be observed in discharges with essentially the same parameters

  9. Calculating the jet quenching parameter in the plasma of noncommutative Yang-Mills theory from gauge/gravity duality

    Science.gov (United States)

    Chakraborty, Somdeb; Roy, Shibaji

    2012-02-01

    A particular decoupling limit of the nonextremal (D1, D3) brane bound state system of type IIB string theory is known to give the gravity dual of space-space noncommutative Yang-Mills theory at finite temperature. We use a string probe in this background to compute the jet quenching parameter in a strongly coupled plasma of hot noncommutative Yang-Mills theory in (3+1) dimensions from gauge/gravity duality. We give expressions for the jet quenching parameter for both small and large noncommutativity. For small noncommutativity, we find that the value of the jet quenching parameter gets reduced from its commutative value. The reduction is enhanced with temperature as T7 for fixed noncommutativity and fixed ’t Hooft coupling. We also give an estimate of the correction due to noncommutativity at the present collider energies like in RHIC or in LHC and find it too small to be detected. We further generalize the results for noncommutative Yang-Mills theories in diverse dimensions.

  10. Influence of Plasma Transferred Arc Process Parameters on Structure and Mechanical Properties of Wear Resistive NiCrBSi-WC/Co Coatings

    Directory of Open Access Journals (Sweden)

    Eitvydas GRUZDYS

    2011-07-01

    Full Text Available Self-fluxing NiCrBSi and related coatings received considerable interest due to their good wear as well as corrosion resistance at moderate and elevated temperatures. Hard tungsten carbide (WC particles can be included in NiCrBSi for further increase of the coating hardness and abrasive wear resistance. Flame spray technique is widely used for fabrication of NiCrBSi films. However, in such a case, subsequent remelting of the deposited coatings by flame, arc discharge or high power laser beam is necessary. In present study NiCrBSi-WC/Co coatings were formed using plasma transferred arc process. By adjusting plasma parameters, such as current, plasma gas flow, shielding gas flow, a number of coatings were formed on steel substrates. Structure of the coatings was investigated using X-ray diffractometry. Microstructure of cross-sectioned coatings was examined using scanning electron microscopy. Hardness of the coating was evaluated by means of the Vickers hardness tests. Wear tests were also performed on specimens to determine resistance to abrasive wear. Acquired results allowed estimating the influence of the deposition process parameters on structure and mechanical properties of the coatings.http://dx.doi.org/10.5755/j01.ms.17.2.482

  11. 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.

  12. The Downwind Hemisphere of the Heliosphere as Observed with IBEX-Lo from 2009 to 2015

    Science.gov (United States)

    Wurz, P.; Galli, A.; Schwadron, N.; Kucharek, H.; Moebius, E.; Bzowski, M.; Sokol, J. M.; Kubiak, M. A.; Funsten, H. O.; Fuselier, S. A.; McComas, D. J.

    2017-12-01

    The topic of this study is the vast region towards the tail of the heliosphere. To this end, we comprehensively analyzed energetic neutral hydrogen atoms (ENAs) of energies 10 eV to 2.5 keV from the downwind hemisphere of the heliosheath measured during the first 7 years of the IBEX (Interstellar Boundary Explorer) mission. Neutralized ions from the heliosheath (the region of slow solar wind plasma between termination shock and heliopause) can be remotely observed as ENAs down to 10 eV with the IBEX-Lo sensor onboard IBEX. This sensor covers those energies of the ion spectrum that dominate the total plasma pressure in the downwind region. So far, this region of the heliosphere has never been explored in-situ. Converting observations obtained near Earth orbit at these low energies to the original ion distributions in the heliocentric rest frame at 100 AU is very challenging, making the assessment of uncertainties and implicit assumptions crucial. From the maps of observed ENAs from the heliosheath and their uncertainties we derive observational constraints on heliospheric models for the downwind hemisphere. These constraints limit the possible range of 1) the distance of the termination shock, 2) the total plasma pressure across the termination shock, 3) the radial flow velocity of the heliosheath plasma, 4) the extinction length of said plasma, and finally 5) the dimension of the heliosheath in downwind directions. Because these parameters are coupled and because of observational limitations, we also need to characterize the degeneracy, i.e., the fact that different sets of parameters may reproduce the observations.

  13. Collision Time Measurements in a Sonoluminescing Microplasma with a Large Plasma Parameter

    Science.gov (United States)

    Bataller, A.; Kappus, B.; Camara, C.; Putterman, S.

    2014-07-01

    The plasma which forms inside of a micron-sized sonoluminescing bubble in water for under a nanosecond has been probed with 3 ns long laser pulses. A comparison of the response to 532 and 1064 nm light indicates that the plasma number density is about 2×1021 cm-3 and that transport properties are dominated by strong screening and correlation effects. The spherical shape, well-defined atomic density, and blackbody temperature make the sonoluminescing plasma a test bed for theories of strongly coupled plasmas. The plasma in this experiment distinguishes between competing theories of strong, intermediate, and weak effective screening.

  14. Influence of laser design parameters on the hydrodynamics of microfusion plasmas

    International Nuclear Information System (INIS)

    Sanmartin, J.R.; Barrero, A.

    1976-01-01

    The quasineutral, oned ) 7mensional motion generated in a cold, infinite, uniform plasma of density n 0 , by the absorption, in a given plane, of a linear pulse of energy per unit time and area phi - phi 0 t/tau, 0 0 2 tau/phi 0 ) 2 /3. )etailed asymptotic results are obtained for both α > 1; the general behaviour of the solution for arbitrary α is discused. The analysis can be easily extended to the case of a plasma initially occuping a half-space, and throws light on the hydrodynamics of laser fusion plasmas. Approximate results existing in the literature for constant irradiation (phi) of a plasma are recovered under appropiate limiting processes. (author). )] [es

  15. Constraining parameters of white-dwarf binaries using gravitational-wave and electromagnetic observations

    International Nuclear Information System (INIS)

    Shah, Sweta; Nelemans, Gijs

    2014-01-01

    The space-based gravitational wave (GW) detector, evolved Laser Interferometer Space Antenna (eLISA) is expected to observe millions of compact Galactic binaries that populate our Milky Way. GW measurements obtained from the eLISA detector are in many cases complimentary to possible electromagnetic (EM) data. In our previous papers, we have shown that the EM data can significantly enhance our knowledge of the astrophysically relevant GW parameters of Galactic binaries, such as the amplitude and inclination. This is possible due to the presence of some strong correlations between GW parameters that are measurable by both EM and GW observations, for example, the inclination and sky position. In this paper, we quantify the constraints in the physical parameters of the white-dwarf binaries, i.e., the individual masses, chirp mass, and the distance to the source that can be obtained by combining the full set of EM measurements such as the inclination, radial velocities, distances, and/or individual masses with the GW measurements. We find the following 2σ fractional uncertainties in the parameters of interest. The EM observations of distance constrain the chirp mass to ∼15%-25%, whereas EM data of a single-lined spectroscopic binary constrain the secondary mass and the distance with factors of two to ∼40%. The single-line spectroscopic data complemented with distance constrains the secondary mass to ∼25%-30%. Finally, EM data on double-lined spectroscopic binary constrain the distance to ∼30%. All of these constraints depend on the inclination and the signal strength of the binary systems. We also find that the EM information on distance and/or the radial velocity are the most useful in improving the estimate of the secondary mass, inclination, and/or distance.

  16. Dynamic plasma screening effects on semiclassical inelastic electron endash ion collisions in dense plasmas

    International Nuclear Information System (INIS)

    Jung, Y.

    1997-01-01

    In dense plasmas, dynamic plasma screening effects are investigated on 1s→2p dipole transition probabilities for electron-impact excitation of hydrogenic ions. The electron endash ion interaction potential is considered by introduction of the plasma dielectric function. A semiclassical straight-line trajectory method is applied to the path of the projectile electron in order to visualize the semiclassical transition probability as a function of the impact parameter, projectile energy, and plasma parameters. The transition probability including the dynamic plasma screening effect is always greater than that including the static plasma screening effect. When the projectile velocity is smaller than the electron thermal velocity, the dynamic polarization screening effect becomes the static plasma screening effect. When the projectile velocity is greater than the electron thermal velocity, then the interaction potential is almost unshielded. The difference between the dynamic and static plasma screening effects is more significant for low-energy projectiles. It is also found that the static plasma screening formula obtained by the Debye endash Hueckel model overestimates the plasma screening effects on the atomic excitation processes in dense plasmas. copyright 1997 American Institute of Physics

  17. Inverse modeling of hydrologic parameters using surface flux and runoff observations in the Community Land Model

    Science.gov (United States)

    Sun, Y.; Hou, Z.; Huang, M.; Tian, F.; Leung, L. Ruby

    2013-12-01

    This study demonstrates the possibility of inverting hydrologic parameters using surface flux and runoff observations in version 4 of the Community Land Model (CLM4). Previous studies showed that surface flux and runoff calculations are sensitive to major hydrologic parameters in CLM4 over different watersheds, and illustrated the necessity and possibility of parameter calibration. Both deterministic least-square fitting and stochastic Markov-chain Monte Carlo (MCMC)-Bayesian inversion approaches are evaluated by applying them to CLM4 at selected sites with different climate and soil conditions. The unknowns to be estimated include surface and subsurface runoff generation parameters and vadose zone soil water parameters. We find that using model parameters calibrated by the sampling-based stochastic inversion approaches provides significant improvements in the model simulations compared to using default CLM4 parameter values, and that as more information comes in, the predictive intervals (ranges of posterior distributions) of the calibrated parameters become narrower. In general, parameters that are identified to be significant through sensitivity analyses and statistical tests are better calibrated than those with weak or nonlinear impacts on flux or runoff observations. Temporal resolution of observations has larger impacts on the results of inverse modeling using heat flux data than runoff data. Soil and vegetation cover have important impacts on parameter sensitivities, leading to different patterns of posterior distributions of parameters at different sites. Overall, the MCMC-Bayesian inversion approach effectively and reliably improves the simulation of CLM under different climates and environmental conditions. Bayesian model averaging of the posterior estimates with different reference acceptance probabilities can smooth the posterior distribution and provide more reliable parameter estimates, but at the expense of wider uncertainty bounds.

  18. Similarity analysis for the high-pressure inductively coupled plasma source

    International Nuclear Information System (INIS)

    Vanden-Abeele, D; Degrez, G

    2004-01-01

    It is well known that the optimal operating parameters of an inductively coupled plasma (ICP) torch strongly depend upon its dimensions. To understand this relationship better, we derive a dimensionless form of the equations governing the behaviour of high-pressure ICPs. The requirement of similarity then naturally leads to expressions for the operating parameters as a function of the plasma radius. In addition to the well-known scaling law for frequency, surprising results appear for the dependence of the mass flow rate, dissipated power and operating pressure upon the plasma radius. While the obtained laws do not appear to be in good agreement with empirical results in the literature, their correctness is supported by detailed numerical calculations of ICP sources of varying diameters. The approximations of local thermodynamic equilibrium and negligible radiative losses restrict the validity of our results and can be responsible for the disagreement with empirical data. The derived scaling laws are useful for the design of new plasma torches and may provide explanations for the unsteadiness observed in certain existing ICP sources

  19. Influence of the choice of internal temperatures on the composition of CxHyOzNt plasmas out of thermodynamic equilibrium: Application to CH2 plasma

    International Nuclear Information System (INIS)

    Koalaga, Zacharie

    2002-01-01

    The purpose of this paper is to study the influence of the choice of internal temperatures on the composition of C x H y O z N t plasmas out of thermodynamic equilibrium. The numerical calculation is specially performed for CH 2 plasma in the pressure range 0.1-1 MPa and for the electron temperature range 5000-30 000 K. Precisely, the investigation of this plasma allows one to show that the choice of internal temperatures can have more influence on plasma composition than the choice of the form of the two-temperature Saha and Guldberg-Waage laws. Indeed, for one of the supposed hypotheses, it is observed that the two forms of the two-temperature system used here can give the same equilibrium composition by uncoupling the excitation temperature of the diatomic and the monatomic species. Great attention must then be given to the adopted hypothesis for internal temperature and not only to the form of the two temperature system used. An accurate comparison between the two models requires the measurement of plasma parameters such as the various internal temperatures and the species concentration. Therefore, we have also carried out an analysis of the potential experimental diagnostics of these plasma parameters. Such diagnostics can help to test and validate theoretical models

  20. Interplay of light and heavy impurities in a fusion plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gaja, Mustafa [IPP, Garching (Germany); Tokar, Mikhail [IEK4, Juelich FZ, Juelich (Germany)

    2016-07-01

    Radiation from impurities eroded from the walls can lead to a broad spectrum of spectacular phenomena in fusion devices An example of such events are breathing oscillations observed in the large helical device (LHD), in long pulse discharges with a stainless steel divertor. They were characterized with oscillations of a period of a second in various plasma parameters. By optimizing magnetic geometry this operation mode, leading to a deteriorate plasma performance, can be avoided. Nonetheless it is of interest and practical importance to understand and firmly predict conditions for breathing phenomenon, in particular, in view of similar impurity environment in W-7 X stellarator. A qualitative explanation for breathing oscillations proposed earlier presumes that they arise due to non-linear synergetic interplay of diverse physical processes. A one-dimensional non-stationary model, describing the generation and transport of main, impurity particles and heat by including the radiation of high-Z (Fe) and low-Z (C and O) impurities is elaborated here. The calculations predict the appearance of oscillations in the relevant range of plasma parameters, reproduce well experimentally observed amplitudes and period of oscillations. It demonstrates that the smaller the fraction of the plasma interaction with a stainless steel surface, the higher the light impurity concentration needed to excite the breathing oscillations. This shows a way to avoid oscillations in future experiments.

  1. Plasma Fibrinolysis Parameters in Smokers and Non-smokers of the Ludwigshafen Risk and Cardiovascular Health (LURIC) Study.

    Science.gov (United States)

    Delgado, Graciela E; Siekmeier, Rüdiger; Krämer, Bernhard K; März, Winfried; Kleber, Marcus E

    2015-01-01

    Cardiovascular diseases (CVD) are an important cause of morbidity and mortality worldwide. Parameters of coagulation and fibrinolysis are risk factors of CVD and might be affected by cigarette smoking. Aim of our study was to analyze the effect of cigarette smoking on parameters of fibrinolysis in active smokers (AS) and life-time non-smokers (NS) of the Ludwigshafen Risk and Cardiovascular Health (LURIC) Study as well as the use of these parameters for risk prediction. We determined plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator antigen (t-PA), protein C activity, and D-dimers in 3,316 LURIC patients. Smoking status was assessed by a questionnaire and measurement of plasma cotinine concentration. Cox regression was used to assess the effect of parameters on mortality. We found that of the 3,316 LURIC patients 777 were AS and 1,178 NS. Within the observation period of 10 years (median) 221 AS and 302 NS died. In male AS vs. NS, PAI-1 (19.0 (10.0-35.0) vs. 15.0 (9.0-29.0) U/ml; p=0.026) and t-PA antigen (12.7 (9.6-16.3) vs. 11.6 (8.9-14.6) μg/l; p=0.020) were slightly increased, while t-PA activity was slightly decreased (0.63 (0.30-1.05) vs. 0.68 (0.42-1.10) U/l; p=0.005). In female AS vs. NS, t-PA antigen (10.5 (8.3-13.9) vs. 11.5 (8.8-15.0) μg/l; p=0.025) and protein C (108.0±24.1% vs. 118.0±25.7%; p=0.004) were decreased. All parameters except for protein C were predictive for mortality in AS. Fully adjusted hazard ratios (95% CI) were 1.14 (1.04-1.25), 1.19 (1.06-1.34), and 1.29 (1.11-1.49) per 1SD increase for D-dimer, t-PA, and PAI-1, respectively. Including fibrinolysis parameters in risk prediction models for mortality improved the area-under-the-curve (AUC) significantly compared with the conventional risk factors. In conclusion, we found alterations in the fibrinolytic system in smokers, which were more pronounced in male AS. PAI-1, t-PA and D-dimers were significant predictors of mortality in AS in LURIC and should be

  2. Microcavity Plasma Devices and Arrays Fabricated in Semiconductor, Ceramic, or Metal/polymer Structures: A New Realm of Plasma Physics and Photonics Applications

    International Nuclear Information System (INIS)

    Eden, J. G.

    2005-01-01

    Micro discharge, or microcavity plasma, is the broad term that has come to be associated with an emerging class of glow discharge devices in which the characteristic spatial dimension of the plasma is nominally ) dia. Si wafers and operated in the rare gases and Ar/N2 gas mixtures. Also, photodetection in the ultraviolet, visible and near-infrared with microplasma devices has been observed by interfacing a low temperature plasma with a semiconductor. Carbon nanotubes grown directly within the microcavity of microplasma devices improve all key performance parameters of the device, and nanoporous Al2O3 grown onto Al by wet chemical processing yields microplasma devices of exceptional stability and lifetime. The opportunities such structures offer for accessing new avenues in plasma physics and photonics will be discussed. (Author)

  3. High-beta plasma effects in a low-pressure helicon plasma

    International Nuclear Information System (INIS)

    Corr, C. S.; Boswell, R. W.

    2007-01-01

    In this work, high-beta plasma effects are investigated in a low-pressure helicon plasma source attached to a large volume diffusion chamber. When operating above an input power of 900 W and a magnetic field of 30 G a narrow column of bright blue light (due to Ar II radiation) is observed along the axis of the diffusion chamber. With this blue mode, the plasma density is axially very uniform in the diffusion chamber; however, the radial profiles are not, suggesting that a large diamagnetic current might be induced. The diamagnetic behavior of the plasma has been investigated by measuring the temporal evolution of the magnetic field (B z ) and the plasma kinetic pressure when operating in a pulsed discharge mode. It is found that although the electron pressure can exceed the magnetic field pressure by a factor of 2, a complete expulsion of the magnetic field from the plasma interior is not observed. In fact, under our operating conditions with magnetized ions, the maximum diamagnetism observed is ∼2%. It is observed that the magnetic field displays the strongest change at the plasma centre, which corresponds to the maximum in the plasma kinetic pressure. These results suggest that the magnetic field diffuses into the plasma sufficiently quickly that on a long time scale only a slight perturbation of the magnetic field is ever observed

  4. Observation of metallic sphere–complex plasma interactions in microgravity

    International Nuclear Information System (INIS)

    Schwabe, M; Zhdanov, S; Hagl, T; Huber, P; Rubin-Zuzic, M; Zaehringer, E; Thomas, H M; Lipaev, A M; Molotkov, V I; Naumkin, V N; Fortov, V E; Vinogradov, P V

    2017-01-01

    The PK-3 Plus laboratory on board the International Space Station is used to study the interaction between metallic spheres and a complex plasma. We show that the metallic spheres significantly affect both the local plasma environment and the microparticle dynamics. The spheres charge under the influence of the plasma and repel the microparticles, forming cavities surrounding the spheres. The size of the cavity around a sphere is used to study the force balance acting on microparticles at the cavity edge. We show that the ion drag force and pressure force from other microparticles balances with the electric force acting from the sphere to within 20%. At intermediate distances from the sphere surface, the interaction between the microparticles and the metallic spheres is attractive due to the drag force stemming from the ions which are moving towards the highly charged spheres. The spheres thus strongly affect the plasma fluxes. This modification of the plasma flux can lead to an effective surface tension acting on the microparticles, and to the excitation of dust-density waves near the spheres, as the local electric field crosses a threshold. (paper)

  5. Plasma confinement using biased electrode in the TCABR tokamak

    International Nuclear Information System (INIS)

    Nascimento, I.C.; Kuznetsov, Y.K.; Severo, J.H.F.; Fonseca, A.M.M.; Elfimov, A.; Bellintani, V.; Heller, M.V.A.P.; Galvao, R.M.O.; Sanada, E.K.; Elizondo, J.I.; Machida, M.

    2005-01-01

    Experimental data obtained on the TCABR tokamak (R = 0.61 m, r = 0.18 m) with an electrally polarized electrode, placed at r = 0.16 m, is reported in this paper. The experiment was performed with plasma current of 90 kA (q 3.1), and hydrogen gas injection adjusted for keeping the electron density at 1.0x10(19) m(-3) without bias. Temporal and radial profiles of plasma parameters with and without bias were measured. The comparison of the profiles shows an increase of the density, up to a maximum factor of 2.6, while H-alpha hydrogen spectral line intensity decreases, and the CIII impurity stays on the same level. The analysis of temporal and radial profiles of plasma parameters indicates that the confined plasma entered in the H-mode regime. The data analysis shows a maximum enhanced confinement factor of 1.95, decaying to 1.5 at the maximum of the density, in comparison with predicted Neo-Alcator scaling law values. Indications of transient increase of the density gradient near the plasma edge were obtained with measurements of density profiles. Calculations of turbulence and transport at the plasma edge, using measured floating potentials and ion saturation currents, show strong decrease in the power spectra and transport. Bifurcation was not observed, and the decrease in the saturation current occurs in 50 microseconds. (author)

  6. The plasma mantle: Composition and other characteristics observed by means of the Prognoz-7 Satellite