Volume generation of negative ions in high density hydrogen discharges

International Nuclear Information System (INIS)

Hiskes, J.R.; Karo, A.M.

1983-01-01

A parametric survey is made of a high-density tandem two-chamber hydrogen negative ion system. The optimum extracted negative ion current densities are sensitive to the atom concentration in the discharge and to the system scale length. For scale lengths ranging from 10 cm to 0.1 cm optimum current densities range from of order 1 to 100 mA cm -2 , respectively

Density- and wavefunction-normalized Cartesian spherical harmonics for l ≤ 20.

Science.gov (United States)

Michael, J Robert; Volkov, Anatoliy

2015-03-01

The widely used pseudoatom formalism [Stewart (1976). Acta Cryst. A32, 565-574; Hansen & Coppens (1978). Acta Cryst. A34, 909-921] in experimental X-ray charge-density studies makes use of real spherical harmonics when describing the angular component of aspherical deformations of the atomic electron density in molecules and crystals. The analytical form of the density-normalized Cartesian spherical harmonic functions for up to l ≤ 7 and the corresponding normalization coefficients were reported previously by Paturle & Coppens [Acta Cryst. (1988), A44, 6-7]. It was shown that the analytical form for normalization coefficients is available primarily for l ≤ 4 [Hansen & Coppens, 1978; Paturle & Coppens, 1988; Coppens (1992). International Tables for Crystallography, Vol. B, Reciprocal space, 1st ed., edited by U. Shmueli, ch. 1.2. Dordrecht: Kluwer Academic Publishers; Coppens (1997). X-ray Charge Densities and Chemical Bonding. New York: Oxford University Press]. Only in very special cases it is possible to derive an analytical representation of the normalization coefficients for 4 4 the density normalization coefficients were calculated numerically to within seven significant figures. In this study we review the literature on the density-normalized spherical harmonics, clarify the existing notations, use the Paturle-Coppens (Paturle & Coppens, 1988) method in the Wolfram Mathematica software to derive the Cartesian spherical harmonics for l ≤ 20 and determine the density normalization coefficients to 35 significant figures, and computer-generate a Fortran90 code. The article primarily targets researchers who work in the field of experimental X-ray electron density, but may be of some use to all who are interested in Cartesian spherical harmonics.

Ball lightning dynamics and stability at moderate ion densities

International Nuclear Information System (INIS)

Morrow, R

2017-01-01

A general mechanism is presented for the dynamics and structure of ball lightning and for the maintenance of the ball lightning structure for several seconds. Results are obtained using a spherical geometry for air at atmospheric pressure, by solving the continuity equations for electrons, positive ions and negative ions coupled with Poisson’s equation. A lightning strike can generate conditions in the lightning channel with a majority of positive nitrogen ions, and a minority of negative oxygen ions and electrons. The calculations are initiated with electrons included; however, at the moderate ion densities chosen the electrons are rapidly lost to form negative ions, and after 1 µ s their influence on the ion dynamics is negligible. Further development after 1 µ s is followed using a simpler set of equations involving only positive ions and negative ions, but including ion diffusion. The space-charge electric field generated by the majority positive ions drives them from the centre of the distribution and drives the minority negative ions and electrons towards the centre of the distribution. In the central region the positive and negative ion distributions eventually overlap exactly and their space-charge fields cancel resulting in zero electric field, and the plasma ball formed is quite stable for a number of seconds. The formation of such plasma balls is not critically dependent on the initial diameter of the ion distributions, or the initial density of minority negative ions. The ion densities decrease relatively slowly due to mutual neutralization of positive and negative ions. The radiation from this neutralization process involving positive nitrogen ions and negative oxygen ions is not sufficient to account for the reported luminosity of ball lightning and some other source of luminosity is shown to be required; the plasma ball model used could readily incorporate other ions in order to account for the luminosity and range of colours reported for ball

Distributions of the ion temperature, ion pressure, and electron density over the current sheet surface

International Nuclear Information System (INIS)

Kyrie, N. P.; Markov, V. S.; Frank, A. G.; Vasilkov, D. G.; Voronova, E. V.

2016-01-01

The distributions of the ion temperature, ion pressure, and electron density over the width (the major transverse dimension) of the current sheet have been studied for the first time. The current sheets were formed in discharges in argon and helium in 2D and 3D magnetic configurations. It is found that the temperature of argon ions in both 2D and 3D magnetic configurations is almost uniform over the sheet width and that argon ions are accelerated by the Ampère force. In contrast, the distributions of the electron density and the temperature of helium ions are found to be substantially nonuniform. As a result, in the 2D magnetic configuration, the ion pressure gradient across the sheet width makes a significant contribution (comparable with the Ampère force) to the acceleration of helium ions, whereas in the 3D magnetic configuration, the Ampère force is counterbalanced by the pressure gradient.

Distributions of the ion temperature, ion pressure, and electron density over the current sheet surface

Energy Technology Data Exchange (ETDEWEB)

Kyrie, N. P., E-mail: kyrie@fpl.gpi.ru; Markov, V. S., E-mail: natalya.kyrie@yandex.ru; Frank, A. G.; Vasilkov, D. G.; Voronova, E. V. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

2016-06-15

The distributions of the ion temperature, ion pressure, and electron density over the width (the major transverse dimension) of the current sheet have been studied for the first time. The current sheets were formed in discharges in argon and helium in 2D and 3D magnetic configurations. It is found that the temperature of argon ions in both 2D and 3D magnetic configurations is almost uniform over the sheet width and that argon ions are accelerated by the Ampère force. In contrast, the distributions of the electron density and the temperature of helium ions are found to be substantially nonuniform. As a result, in the 2D magnetic configuration, the ion pressure gradient across the sheet width makes a significant contribution (comparable with the Ampère force) to the acceleration of helium ions, whereas in the 3D magnetic configuration, the Ampère force is counterbalanced by the pressure gradient.

Investigation of the silicon ion density during molecular beam epitaxy growth

CERN Document Server

Eifler, G; Ashurov, K; Morozov, S

2002-01-01

Ions impinging on a surface during molecular beam epitaxy influence the growth and the properties of the growing layer, for example, suppression of dopant segregation and the generation of crystal defects. The silicon electron gun in the molecular beam epitaxy (MBE) equipment is used as a source for silicon ions. To use the effect of ion bombardment the mechanism of generation and distribution of ions was investigated. A monitoring system was developed and attached at the substrate position in the MBE growth chamber to measure the ion and electron densities towards the substrate. A negative voltage was applied to the substrate to modify the ion energy and density. Furthermore the current caused by charge carriers impinging on the substrate was measured and compared with the results of the monitoring system. The electron and ion densities were measured by varying the emission current of the e-gun achieving silicon growth rates between 0.07 and 0.45 nm/s and by changing the voltage applied to the substrate betw...

Ion acoustic solitons/double layers in two-ion plasma revisited

International Nuclear Information System (INIS)

Lakhina, G. S.; Singh, S. V.; Kakad, A. P.

2014-01-01

Ion acoustic solitons and double layers are studied in a collisionless plasma consisting of cold heavier ion species, a warm lighter ion species, and hot electrons having Boltzmann distributions by Sagdeev pseudo-potential technique. In contrast to the previous results, no double layers and super-solitons are found when both the heavy and lighter ion species are treated as cold. Only the positive potential solitons are found in this case. When the thermal effects of the lighter ion species are included, in addition to the usual ion-acoustic solitons occurring at M > 1 (where the Mach number, M, is defined as the ratio of the speed of the solitary wave and the ion-acoustic speed considering temperature of hot electrons and mass of the heavier ion species), slow ion-acoustic solitons/double layers are found to occur at low Mach number (M < 1). The slow ion-acoustic mode is actually a new ion-ion hybrid acoustic mode which disappears when the normalized number density of lighter ion species tends to 1 (i.e., no heavier species). An interesting property of the new slow ion-acoustic mode is that at low number density of the lighter ion species, only negative potential solitons/double layers are found whereas for increasing densities there is a transition first to positive solitons/double layers, and then only positive solitons. The model can be easily applicable to the dusty plasmas having positively charged dust grains by replacing the heavier ion species by the dust mass and doing a simple normalization to take account of the dust charge

Evaluation of the ion-density measurements by the Indian satellite SROSS-C2

Science.gov (United States)

Subrahmanyam, P.; Jain, A. R.; Maini, H. K.; Bahl, M.; Das, Rupesh M.; Garg, S. C.; Niranjan, K.

2010-12-01

The ion and electron F region plasma measurements made by the ion and electron Retarding Potential Analyzers (RPAs) onboard the Indian satellite SROSS-C2, have yielded excellent data set over the Indian region for more than half a solar cycle, after the SROSS-C2 launch in May 1994. The absolute ion density, ion temperature, and ion composition parameters are derived from these in situ measurements and used by many workers. In this paper the absolute values of ion density derived from the ion RPA measurements are compared and evaluated with the measurements made by ground-based ionosondes located in the Indian region and close to the SROSS-C2 orbital path. It is shown that a slight adjustment in efficiency factor of the ion RPA sensor brings the in situ measurements much closer to those obtained from the ground-based ionosonde measurements taking into account the model calculations. It may be mentioned that this is a correction to the ion density measurement by SROSS-C2 by a fixed proportion (14-11.4%). The effect of change in efficiency factor on the ion current, which is used to deduce the ion number density, is demonstrated and discussed.

Density changes in amorphous Pd80Si20 during low temperature ion irradiation

International Nuclear Information System (INIS)

Schumacher, G.; Birtcher, R.C.; Rehn, L.E.

1994-11-01

Density changes in amorphous Pd 80 Si 20 during ion irradiation below 100K were detected by in situ HVEM measurements of the changes in specimen length as a function of ion fluence. A decrease in mass density as a function of the ion fluence was observed. The saturation value of the change in mass density was determined to be approximately -1.2%

Experimental observations of anomalous potential drops over ion density cavities

International Nuclear Information System (INIS)

Bohm, M.

1991-08-01

Experiments are reported showing the plasma potential response when a step voltage is applied over the plasma column between the two plasma sources in a triple plasma machine. The time resolution is sufficient to resolve potential variations caused essentially by the electron motion, and two independent probe methods are used to obtain this time resolution. Depending on the initial conditions two different responses were observed on the time scale of the electron motion. When the initial ion density varies along the plasma column and has a local minimum (that is, forms an ion density cavity), the applied potential drop becomes distributed over the cavity after a few electron transit times. Later the profile steepens to a double layer on the time scale of the ion motion. The width of the cavity is comparable to the length of the plasma column. When the initial density is axially uniform, most of the potential drop instead concentrates to a narrow region at the low potential end of the plasma column after a few electron transit times. On the time scale of the ion motion this potential drop begins to propagate into the plasma as a double layer. The results obtained are consistent with those from numerical simulations with similar boundary conditions. Further experiments are necessary to get conclusive insight into the voltage supporting capability of an ion density cavity. (au) (34 refs.)

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.)

US Heavy Ion Beam Research for Energy Density Physics Applications and Fusion

International Nuclear Information System (INIS)

Davidson, R.C.; Logan, B.G.; Barnard, J.J.; Bieniosek, F.M.; Briggs, R.J.; Callahan D.A.; Kireeff Covo, M.; Celata, C.M.; Cohen, R.H.; Coleman, J.E.; Debonnel, C.S.; Grote, D.P.; Efthimiom, P.C.; Eylon, S.; Friedman, A.; Gilson, E.P.; Grisham, L.R.; Henestroza, E.; Kaganovich, I.D.; Kwan, J.W.; Lee, E.P.; Lee, W.W.; Leitner, M.; Lund, S.M.; Meier, W.R.; Molvik, A.W.; Olson, C.L.; Penn, G.E.; Qin, H.; Roy, P.K.; Rose, D.V.; Sefkow, A.; Seidl, P.A.; Sharp, W.M.; Startsev, E.A.; Tabak, M.; Thoma, C.; Vay, J-L; Wadron, W.L.; Wurtele, J.S.; Welch, D.R.; Westenskow, G.A.; Yu, S.S.

2005-01-01

Key scientific results from recent experiments, modeling tools, and heavy ion accelerator research are summarized that explore ways to investigate the properties of high energy density matter in heavy-ion-driven targets, in particular, strongly-coupled plasmas at 0.01 to 0.1 times solid density for studies of warm dense matter, which is a frontier area in high energy density physics. Pursuit of these near-term objectives has resulted in many innovations that will ultimately benefit heavy ion inertial fusion energy. These include: neutralized ion beam compression and focusing, which hold the promise of greatly improving the stage between the accelerator and the target chamber in a fusion power plant; and the Pulse Line Ion Accelerator (PLIA), which may lead to compact, low-cost modular linac drivers

Long-time evolution of a low-density ion beam

International Nuclear Information System (INIS)

Zachary, A.L.; Cohen, B.I.; Max, C.E.; Arons, J.

1989-01-01

With a new, orbit-averaged hybrid computer simulation code, we study a cold, fast low-density ion beam which propagates along the ambient magnetic field as it interacts with a much denser fluid background. We examine the character of the interactions as we vary the ion beam density relative to the background density over the range 1 x 10/sup -5/ to 3 x 10/sup -3/. The low beam density simulations may not be directly observable upstream of the Earth's bow shock, but they are included to help develop an understanding of the results seen in the simulations with high-beam density. However, our highest density simulation falls within the range of solar wind data. All the simulations, regardless of the relative beam density, show three distinct phases: (1) an early or ''linear'' phase; (2) an intermediate or ''trapping'' phase; and (3) a late or ''decorrelation'' phase. In the early phase, the beam excites a nearly monochromatic Alfven wave whose amplitude grows exponentially at a rate given by linear perturbation theory. The wave amplitude saturates when the linear growth rate is of the order of the trapping frequency

Low-emittance uniform density Cs+ sources for heavy ion fusion accelerators studies

International Nuclear Information System (INIS)

Eylon, S.; Henestroza, E.; Garvey, T.; Johnson, R.; Chupp, W.

1991-04-01

Low-emittance (high-brightness) Cs + thermionic sources were developed for the heavy ion induction linac experiment MBE-4 at LBL. The MBE-4 linac accelerates four 10 mA beams from 200 ke V to 900 ke V while amplifying the current up to a factor of nine. Recent studies of the transverse beam dynamics suggested that characteristics of the injector geometry were contributing to the normalized transverse emissions growth. Phase-space and current density distribution measurements of the beam extracted from the injector revealed overfocusing of the outermost rays causing a hollow density profile. We shall report on the performance of a 5 mA scraped beam source (which eliminates the outermost beam rays in the diode) and on the design of an improved 10 mA source. The new source is based on EGUN calculations which indicated that a beam with good emissions and uniform current density could be obtained by modifying the cathode Pierce electrodes and using a spherical emitting surface. The measurements of the beam current density profile on a test stand were found to be in agreement with the numerical simulations. 3 refs., 6 figs

Achieving high baryon densities in the fragmentation regions in heavy ion collisions at top RHIC energy

International Nuclear Information System (INIS)

Li, Ming; Kapusta, Joseph I.

2017-01-01

Heavy ion collisions at extremely high energy, such as the top energy at RHIC, exhibit the property of transparency where there is a clear separation between the almost net-baryon-free central rapidity region and the net-baryon-rich fragmentation region. We calculate the net-baryon rapidity loss and the nuclear excitation energy using the energy-momentum tensor obtained from the McLerran-Venugopalan model. Nuclear compression during the collision is further estimated using a simple space-time picture. The results show that extremely high baryon densities, about twenty times larger than the normal nuclear density, can be achieved in the fragmentation regions. (paper)

Measuring the radial density distribution of light emission around the track of fast ions in nitrogen

International Nuclear Information System (INIS)

Ibach, T.

1983-01-01

For analysing the emission and stopping of ionization electrons (σ-electrons) emitted by fast ions passing through a gas, the radial density distribution of the light emission of the (0,0) transition of two optical bands in nitrogen have been measured. The systems selected for the epxeriments are the 2nd positive system (2.PS) at 337.1 nm primarily excited by low-energy electrons of about 20 eV, and the first negative system (1.NS) at 391.4 nm excited by faster electrons and simultaneous ionization. The equipment developed for the experiments records the light emission with a telescope-type optical arrangement including interference filters, allowing high local resolution and dynamics of the measured range. The measurements have been carried out at pressures between 0.133 and 13.3 mbar, using photons of energies ranging from 270 keV to 2.8 MeV, helium 3 beams of 270 keV/u and 500 keV/u, and neon beams of 270 keV/u. Abel's inversion applied to the distance functions allows calculation of the spatial light emission density which is normalized for a gas density of 1 g/cm 3 . The profiles of the two bands indicate that the σ-electron spectrum gets harder in outward direction. Next to the beam the impact density decreases faster with increasing ion energy than the stopping power (increasing interaction range of the σ-electrons). With photon beams, about half of the whole light emission in the 1. NS, and of the ionization, is induced by primary interactions of the ion beam. This proportion decreases at constant energy per nucleon with increasing atomic number of the ions as compared with the σ-electrons. The primary σ-emission gets harder with higher atomic numbers. (orig./HP) [de

Pulsed, Inductively Generated, Streaming Plasma Ion Source for Heavy Ion Fusion Linacs

International Nuclear Information System (INIS)

Steven C. Glidden; Howard D Sanders; John B. Greenly; Daniel L. Dongwoo

2006-01-01

This report describes a compact, high current density, pulsed ion source, based on electrodeless, inductively driven gas breakdown, developed to meet the requirements on normalized emittance, current density, uniformity and pulse duration for an ion injector in a heavy-ion fusion driver. The plasma source produces >10 (micro)s pulse of Argon plasma with ion current densities >100 mA/cm2 at 30 cm from the source and with strongly axially directed ion energy of about 80 eV, and sub-eV transverse temperature. The source has good reproducibility and spatial uniformity. Control of the current density during the pulse has been demonstrated with a novel modulator coil method which allows attenuation of the ion current density without significantly affecting the beam quality. This project was carried out in two phases. Phase 1 used source configurations adapted from light ion sources to demonstrate the feasibility of the concept. In Phase 2 the performance of the source was enhanced and quantified in greater detail, a modulator for controlling the pulse shape was developed, and experiments were conducted with the ions accelerated to >40 kV

Highly Compressed Ion Beams for High Energy Density Science

CERN Document Server

Friedman, Alex; Briggs, Richard J; Callahan, Debra; Caporaso, George; Celata, C M; Davidson, Ronald C; Faltens, Andy; Grant-Logan, B; Grisham, Larry; Grote, D P; Henestroza, Enrique; Kaganovich, Igor D; Lee, Edward; Lee, Richard; Leitner, Matthaeus; Nelson, Scott D; Olson, Craig; Penn, Gregory; Reginato, Lou; Renk, Tim; Rose, David; Sessler, Andrew M; Staples, John W; Tabak, Max; Thoma, Carsten H; Waldron, William; Welch, Dale; Wurtele, Jonathan; Yu, Simon

2005-01-01

The Heavy Ion Fusion Virtual National Laboratory (HIF-VNL) is developing the intense ion beams needed to drive matter to the High Energy Density (HED) regimes required for Inertial Fusion Energy (IFE) and other applications. An interim goal is a facility for Warm Dense Matter (WDM) studies, wherein a target is heated volumetrically without being shocked, so that well-defined states of matter at 1 to 10 eV are generated within a diagnosable region. In the approach we are pursuing, low to medium mass ions with energies just above the Bragg peak are directed onto thin target "foils," which may in fact be foams or "steel wool" with mean densities 1% to 100% of solid. This approach complements that being pursued at GSI, wherein high-energy ion beams deposit a small fraction of their energy in a cylindrical target. We present the requirements for warm dense matter experiments, and describe suitable accelerator concepts, including novel broadband traveling wave pulse-line, drift-tube linac, RF, and single-gap approa...

Restoring the consistency with the contact density theorem of a classical density functional theory of ions at a planar electrical double layer.

Science.gov (United States)

Gillespie, Dirk

2014-11-01

Classical density functional theory (DFT) of fluids is a fast and efficient theory to compute the structure of the electrical double layer in the primitive model of ions where ions are modeled as charged, hard spheres in a background dielectric. While the hard-core repulsive component of this ion-ion interaction can be accurately computed using well-established DFTs, the electrostatic component is less accurate. Moreover, many electrostatic functionals fail to satisfy a basic theorem, the contact density theorem, that relates the bulk pressure, surface charge, and ion densities at their distances of closest approach for ions in equilibrium at a smooth, hard, planar wall. One popular electrostatic functional that fails to satisfy the contact density theorem is a perturbation approach developed by Kierlik and Rosinberg [Phys. Rev. A 44, 5025 (1991)PLRAAN1050-294710.1103/PhysRevA.44.5025] and Rosenfeld [J. Chem. Phys. 98, 8126 (1993)JCPSA60021-960610.1063/1.464569], where the full free-energy functional is Taylor-expanded around a bulk (homogeneous) reference fluid. Here, it is shown that this functional fails to satisfy the contact density theorem because it also fails to satisfy the known low-density limit. When the functional is corrected to satisfy this limit, a corrected bulk pressure is derived and it is shown that with this pressure both the contact density theorem and the Gibbs adsorption theorem are satisfied.

Effects of the instability enhanced friction on relative ion densities in a two-ion species low-temperature plasma

Science.gov (United States)

Vukovic, Mirko

2011-10-01

The instability enhanced friction theory of Baalrud & Hegna (Phys. Plasmas 18, 023505 (2011)) predicts that for comparable ion densities the ions nearly reach a common velocity near the sheath edge in a low temperature plasma. The theory was experimentally confirmed by Yip, Hershkowitz, & Severn (Phys. Rev. Letters 104, 225003 (2010)). We will explore the effects of the theory on relative ion densities in a numerical simulation of an Ar/Xe plasma. Results for a 0D plasma model (Lieberman, Lichtenberg, Principles of Plasma Discharges and Materials Processing, 2005) will be presented.

Electron and Negative Ion Densities in C2F6 and CHF3 Containing Inductively Coupled Discharges

International Nuclear Information System (INIS)

HEBNER, GREGORY A.; MILLER, PAUL A.

1999-01-01

Electron and negative ion densities have been measured in inductively coupled discharges containing C 2 F 6 and CHF 3 . Line integrated electron density was determined using a microwave interferometer, negative ion densities were inferred using laser photodetachment spectroscopy, and electron temperature was determined using a Langmuir probe. For the range of induction powers, pressures and bias power investigated, the electron density peaked at 9 x 10 12 cm -2 (line-integrated) or approximately 9 x 10 11 cm -3 . The negative ion density peaked at approximately 1.3 x 10 11 cm -3 . A maximum in the negative ion density as a function of induction coil power was observed. The maximum is attributed to a power dependent change in the density of one or more of the potential negative ion precursor species since the electron temperature did not depend strongly on power. The variation of photodetachment with laser wavelength indicated that the dominant negative ion was F - . Measurement of the decay of the negative ion density in the afterglow of a pulse modulated discharge was used to determine the ion-ion recombination rate for CF 4 , C 2 F 6 and CHF 3 discharges

High-ion temperature experiments with negative-ion-based NBI in LHD

International Nuclear Information System (INIS)

Takeiri, Y.; Morita, S.; Tsumori, K.; Ikeda, K.; Oka, Y.; Osakabe, M.; Nagaoka, K.; Goto, M.; Miyazawa, J.; Masuzaki, S.; Ashikawa, N.; Yokoyama, M.; Narihara, K.; Yamada, I.; Kubo, S.; Shimozuma, T.; Inagaki, S.; Tanaka, K.; Peterson, B.J.; Ida, K.; Kaneko, O.; Komori, A.; Murakami, S.

2005-01-01

High-Z plasmas have been produced with Ar- and/or Ne-gas fuelling to increase the ion temperature in the LHD plasmas heated with the high-energy negative-ion-based NBI. Although the electron heating is dominant in the high-energy NBI heating, the direct ion heating power is much enhanced effectively in low-density plasmas due to both an increase in the beam absorption (ionisation) power and a reduction of the ion density in the high-Z plasmas. Intensive Ne- and/or Ar-glow discharge cleaning works well to suppress dilution of the high-Z plasmas with the wall-absorbed hydrogen. As a result, the ion temperature increases with an increase in the ion heating power normalized by the ion density, and reaches 10 keV. An increase in the ion temperature is also observed with an addition of the centrally focused ECRH to the low-density and high-Z NBI plasma, suggesting improvement of the ion transport. The results obtained in the high-Z plasma experiments with the high-energy NBI heating indicate that an increase in the direct ion heating power and improvement of the ion transport are essential to the ion temperature rise, and that a high-ion temperature would be obtained as well in hydrogen plasmas with low-energy positive-NBI heating which is planed in near future in LHD. (author)

Fast-scan monitor examines neutral-beam ion-density profile

International Nuclear Information System (INIS)

Anon.

1978-01-01

All of the magnetic mirror confinement fusion experiments at LLL and at other laboratories depend on pulsed, energetic neutral-beam injection for fueling and imparting energy to the trapped plasma for density build-up and stability studies. It is vital to be able to monitor how well the injected ion beam is aimed and focused. To do this, we have designed an ion-beam current-density profile monitor that uses a commercial minimodular data acquisition system. Our prototype model monitors a single 20-kV, 50-A, 10-ms beam. However, the method is applicable to any number of beams with similar sampling target arrays. Also, the electronics can be switched to monitor any one of several target collectors

Real-time control of ion density and ion energy in chlorine inductively coupled plasma etch processing

International Nuclear Information System (INIS)

Chang, C.-H.; Leou, K.-C.; Lin Chaung; Lin, T.-L.; Tseng, C.-W.; Tsai, C.-H.

2003-01-01

In this study, we have experimentally demonstrated the real-time closed-loop control of both ion density and ion energy in a chlorine inductively coupled plasma etcher. To measure positive ion density, the trace rare gases-optical emission spectroscopy is used to measure the chlorine positive ion density. An rf voltage probe is adopted to measure the root-mean-square rf voltage on the electrostatic chuck which is linearly dependent on sheath voltage. One actuator is a 13.56 MHz rf generator to drive the inductive coil seated on a ceramic window. The second actuator is also a 13.56 MHz rf generator to power the electrostatic chuck. The closed-loop controller is designed to compensate for process drift, process disturbance, and pilot wafer effect and to minimize steady-state error of plasma parameters. This controller has been used to control the etch process of unpatterned polysilicon. The experimental results showed that the closed-loop control had a better repeatability of plasma parameters compared with open-loop control. The closed-loop control can eliminate the process disturbance resulting from reflected power. In addition, experimental results also demonstrated that closed-loop control has a better reproducibility in etch rate as compared with open-loop control

Determination of plasma density from data on the ion current to cylindrical and planar probes

Energy Technology Data Exchange (ETDEWEB)

Voloshin, D. G., E-mail: dvoloshin@mics.msu.su; Vasil’eva, A. N.; Kovalev, A. S.; Mankelevich, Yu. A.; Rakhimova, T. V. [Moscow State University, Skobeltsyn Nuclear Physics Institute (Russian Federation)

2016-12-15

To improve probe methods of plasma diagnostics, special probe measurements were performed and numerical models describing ion transport to a probe with allowance for collisions were developed. The current–voltage characteristics of cylindrical and planar probes were measured in an RF capacitive discharge in argon at a frequency of 81 MHz and plasma densities of 10{sup 10}–10{sup 11} cm{sup –3}, typical of modern RF reactors. 1D and 2D numerical models based on the particle-in-cell method with Monte Carlo collisions for simulating ion motion and the Boltzmann equilibrium for electrons are developed to describe current collection by a probe. The models were used to find the plasma density from the ion part of the current–voltage characteristic, study the effect of ion collisions, and verify simplified approaches to determining the plasma density. A 1D hydrodynamic model of the ion current to a cylindrical probe with allowance for ion collisions is proposed. For a planar probe, a method to determine the plasma density from the averaged numerical results is developed. A comparative analysis of different approaches to calculating the plasma density from the ion current to a probe is performed.

Comparison of measured and modelled negative hydrogen ion densities at the ECR-discharge HOMER

Science.gov (United States)

Rauner, D.; Kurutz, U.; Fantz, U.

2015-04-01

As the negative hydrogen ion density nH- is a key parameter for the investigation of negative ion sources, its diagnostic quantification is essential in source development and operation as well as for fundamental research. By utilizing the photodetachment process of negative ions, generally two different diagnostic methods can be applied: via laser photodetachment, the density of negative ions is measured locally, but only relatively to the electron density. To obtain absolute densities, the electron density has to be measured additionally, which induces further uncertainties. Via cavity ring-down spectroscopy (CRDS), the absolute density of H- is measured directly, however LOS-averaged over the plasma length. At the ECR-discharge HOMER, where H- is produced in the plasma volume, laser photodetachment is applied as the standard method to measure nH-. The additional application of CRDS provides the possibility to directly obtain absolute values of nH-, thereby successfully bench-marking the laser photodetachment system as both diagnostics are in good agreement. In the investigated pressure range from 0.3 to 3 Pa, the measured negative hydrogen ion density shows a maximum at 1 to 1.5 Pa and an approximately linear response to increasing input microwave powers from 200 up to 500 W. Additionally, the volume production of negative ions is 0-dimensionally modelled by balancing H- production and destruction processes. The modelled densities are adapted to the absolute measurements of nH- via CRDS, allowing to identify collisions of H- with hydrogen atoms (associative and non-associative detachment) to be the dominant loss process of H- in the plasma volume at HOMER. Furthermore, the characteristic peak of nH- observed at 1 to 1.5 Pa is identified to be caused by a comparable behaviour of the electron density with varying pressure, as ne determines the volume production rate via dissociative electron attachment to vibrationally excited hydrogen molecules.

Cholesterol transfer from normal and atherogenic low density lipoproteins to Mycoplasma membranes

International Nuclear Information System (INIS)

Mitschelen, J.J.; St Clair, R.W.; Hester, S.H.

1981-01-01

The purpose of this study was to determine whether the free cholesterol of hypercholesterolemic low density lipoprotein from cholesterol-fed nonhuman primates has a greater potential for surface transfer to cell membranes than does the free cholesterol of normal low density lipoprotein. The low density lipoproteins were isolated from normal and hypercholesterolemic rhesus and cynomolgus monkeys, incubated with membranes from Acholeplasma laidlawii, a mycoplasma species devoid of cholesterol in its membranes, and the mass transfer of free cholesterol determined by measuring membrane cholesterol content. Since these membranes neither synthesize nor esterify cholesterol, nor degrade the protein or cholesterol ester moieties of low density lipoprotein, they are an ideal model with which to study differences in the cholesterol transfer potential of low density lipoprotein independent of the uptake of the intact low density lipoprotein particle. These studies indicate that, even though there are marked differences in the cholesterol composition of normal and hypercholesterolemic low density lipoproteins, this does not result in a greater chemical potential for surface transfer of free cholesterol. Consequently, if a difference in the surface transfer of free cholesterol is responsible for the enhanced ability of hypercholesterolemic low density lipoprotein to promote cellular cholesterol accumulation and, perhaps, also atherosclerosis, it must be the result of differences in the interaction to the hypercholesterolemic low density lipoprotein with the more complicated mammalian cell membranes, rather than differences in the chemical potential for cholesterol transfer

U.S. Heavy Ion Beam Research for High Energy Density Physics Applications and Fusion

International Nuclear Information System (INIS)

Davidson, R.C.; Logan, B.G.; Barnard, J.J.; Bieniosek, F.M.; Briggs, R.J.

2005-01-01

Key scientific results from recent experiments, modeling tools, and heavy ion accelerator research are summarized that explore ways to investigate the properties of high energy density matter in heavy-ion-driven targets, in particular, strongly-coupled plasmas at 0.01 to 0.1 times solid density for studies of warm dense matter, which is a frontier area in high energy density physics. Pursuit of these near-term objectives has resulted in many innovations that will ultimately benefit heavy ion inertial fusion energy. These include: neutralized ion beam compression and focusing, which hold the promise of greatly improving the stage between the accelerator and the target chamber in a fusion power plant; and the Pulse Line Ion Accelerator (PLIA), which may lead to compact, low-cost modular linac drivers

Destructive role of hot ions in the formation of electrostatic density humps and dips in dusty plasmas

International Nuclear Information System (INIS)

Mahmood, S.; Saleem, H.

2003-01-01

It is shown that the ion thermal energy is destructive for the ion acoustic solitons in the presence of dust, and it decreases the value of Mach number for the formation of solitary structures. The regions of ion density humps and dips are produced simultaneously, corresponding to positive and negative values of the electrostatic potential. The nonlinear electron density also behaves in a similar fashion as that of ions. However, the dust density increases in the regions where the ion and electron densities are depleted and vice versa

2D electron density profile measurement in tokamak by laser-accelerated ion-beam probe.

Science.gov (United States)

Chen, Y H; Yang, X Y; Lin, C; Wang, L; Xu, M; Wang, X G; Xiao, C J

2014-11-01

A new concept of Heavy Ion Beam Probe (HIBP) diagnostic has been proposed, of which the key is to replace the electrostatic accelerator of traditional HIBP by a laser-driven ion accelerator. Due to the large energy spread of ions, the laser-accelerated HIBP can measure the two-dimensional (2D) electron density profile of tokamak plasma. In a preliminary simulation, a 2D density profile was reconstructed with a spatial resolution of about 2 cm, and with the error below 15% in the core region. Diagnostics of 2D density fluctuation is also discussed.

Effect of 50 and 80 MeV phosphorous ions on the contribution of interface and oxide state density in n-channel MOSFETs

Energy Technology Data Exchange (ETDEWEB)

Shinde, N.S.; Dhole, S.D.; Kanjilal, D.; Bhoraskar, V.N. E-mail: vnb@physics.unipune.ernet.in

1999-07-02

n-channel depletion MOS devices were irradiated with 50 and 80 MeV phosphorous ions, with different fluences varying in the range from 10{sup 11} to 10{sup 13} ions/cm{sup 2}. The pre and post irradiation I-V characteristics were measured and the corresponding threshold shift {delta}V{sub TH} was estimated. In both the cases, the drain current I{sub D} and the threshold voltage V{sub TH} were found to decrease with the ion fluence. The increase in the threshold voltage shift {delta}V{sub TH} with the ion fluence, was greater for the devices irradiated with 80 MeV ions than those irradiated with 50 MeV ions. The interface and oxide state densities were determined through the subthreshold voltage measurements. To separate the contributions of oxide and interface states towards the threshold voltage shift, the ion irradiated MOS devices were annealed at 150 deg. C. The threshold shift during annealing initially decreased and later increased with increasing annealing period. The rate of change of the interface states during annealing was higher than that of the oxide states. It was also found that depletion mode (normally ON) MOSFETs switched operation to enhancement mode (normally OFF)

Determination of Hydrogen Density by Swift Heavy Ions.

Science.gov (United States)

Xu, Ge; Barriga-Carrasco, M D; Blazevic, A; Borovkov, B; Casas, D; Cistakov, K; Gavrilin, R; Iberler, M; Jacoby, J; Loisch, G; Morales, R; Mäder, R; Qin, S-X; Rienecker, T; Rosmej, O; Savin, S; Schönlein, A; Weyrich, K; Wiechula, J; Wieser, J; Xiao, G Q; Zhao, Y T

2017-11-17

A novel method to determine the total hydrogen density and, accordingly, a precise plasma temperature in a lowly ionized hydrogen plasma is described. The key to the method is to analyze the energy loss of swift heavy ions interacting with the respective bound and free electrons of the plasma. A slowly developing and lowly ionized hydrogen theta-pinch plasma is prepared. A Boltzmann plot of the hydrogen Balmer series and the Stark broadening of the H_{β} line preliminarily defines the plasma with a free electron density of (1.9±0.1)×10^{16}  cm^{-3} and a free electron temperature of 0.8-1.3 eV. The temperature uncertainty results in a wide hydrogen density, ranging from 2.3×10^{16} to 7.8×10^{18}  cm^{-3}. A 108 MHz pulsed beam of ^{48}Ca^{10+} with a velocity of 3.652  MeV/u is used as a probe to measure the total energy loss of the beam ions. Subtracting the calculated energy loss due to free electrons, the energy loss due to bound electrons is obtained, which linearly depends on the bound electron density. The total hydrogen density is thus determined as (1.9±0.7)×10^{17}  cm^{-3}, and the free electron temperature can be precisely derived as 1.01±0.04  eV. This method should prove useful in many studies, e.g., inertial confinement fusion or warm dense matter.

Comparison of measured and modelled negative hydrogen ion densities at the ECR-discharge HOMER

Energy Technology Data Exchange (ETDEWEB)

Rauner, D.; Kurutz, U.; Fantz, U. [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); AG Experimentelle Plasmaphysik, Universität Augsburg, 86135 Augsburg (Germany)

2015-04-08

As the negative hydrogen ion density n{sub H{sup −}} is a key parameter for the investigation of negative ion sources, its diagnostic quantification is essential in source development and operation as well as for fundamental research. By utilizing the photodetachment process of negative ions, generally two different diagnostic methods can be applied: via laser photodetachment, the density of negative ions is measured locally, but only relatively to the electron density. To obtain absolute densities, the electron density has to be measured additionally, which induces further uncertainties. Via cavity ring-down spectroscopy (CRDS), the absolute density of H{sup −} is measured directly, however LOS-averaged over the plasma length. At the ECR-discharge HOMER, where H{sup −} is produced in the plasma volume, laser photodetachment is applied as the standard method to measure n{sub H{sup −}}. The additional application of CRDS provides the possibility to directly obtain absolute values of n{sub H{sup −}}, thereby successfully bench-marking the laser photodetachment system as both diagnostics are in good agreement. In the investigated pressure range from 0.3 to 3 Pa, the measured negative hydrogen ion density shows a maximum at 1 to 1.5 Pa and an approximately linear response to increasing input microwave powers from 200 up to 500 W. Additionally, the volume production of negative ions is 0-dimensionally modelled by balancing H{sup −} production and destruction processes. The modelled densities are adapted to the absolute measurements of n{sub H{sup −}} via CRDS, allowing to identify collisions of H{sup −} with hydrogen atoms (associative and non-associative detachment) to be the dominant loss process of H{sup −} in the plasma volume at HOMER. Furthermore, the characteristic peak of n{sub H{sup −}} observed at 1 to 1.5 Pa is identified to be caused by a comparable behaviour of the electron density with varying pressure, as n{sub e} determines

Effects of low central fuelling on density and ion temperature profiles in reversed shear plasmas on JT-60U

Energy Technology Data Exchange (ETDEWEB)

Takenaga, H; Ide, S; Sakamoto, Y; Fujita, T [Japan Atomic Energy Agency, Naka Ibaraki 311-0193 (Japan)], E-mail: takenaga.hidenobu@jaea.go.jp

2008-07-15

Effects of low central fuelling on density and ion temperature profiles have been investigated using negative ion based neutral beam injection and electron cyclotron heating (ECH) in reversed shear plasmas on JT-60U. Strong internal transport barrier (ITB) was maintained in density and ion temperature profiles, when central fuelling was decreased by switching positive ion based neutral beam injection to ECH after the strong ITB formation. Similar density and ion temperature ITBs were formed for the low and high central fuelling cases during the plasma current ramp-up phase. Strong correlation between the density gradient and the ion temperature gradient was observed, indicating that particle transport and ion thermal transport are strongly coupled or the density gradient assists the ion temperature ITB formation through suppression of drift wave instabilities such as ion temperature gradient mode. These results support that the density and ion temperature ITBs can be formed under reactor relevant conditions.

Effects of low central fuelling on density and ion temperature profiles in reversed shear plasmas on JT-60U

Science.gov (United States)

Takenaga, H.; Ide, S.; Sakamoto, Y.; Fujita, T.; JT-60 Team

2008-07-01

Effects of low central fuelling on density and ion temperature profiles have been investigated using negative ion based neutral beam injection and electron cyclotron heating (ECH) in reversed shear plasmas on JT-60U. Strong internal transport barrier (ITB) was maintained in density and ion temperature profiles, when central fuelling was decreased by switching positive ion based neutral beam injection to ECH after the strong ITB formation. Similar density and ion temperature ITBs were formed for the low and high central fuelling cases during the plasma current ramp-up phase. Strong correlation between the density gradient and the ion temperature gradient was observed, indicating that particle transport and ion thermal transport are strongly coupled or the density gradient assists the ion temperature ITB formation through suppression of drift wave instabilities such as ion temperature gradient mode. These results support that the density and ion temperature ITBs can be formed under reactor relevant conditions.

High energy density in matter produced by heavy ion beams

International Nuclear Information System (INIS)

1987-08-01

This annual report summarizes the results of research carried out in 1986 within the framework of the program 'High Energy Density in Matter Produced by Heavy Ion Beams' which is funded by the Federal Ministry for Research and Technology. Its initial motivation and its ultimate goal is the question whether inertial confinement can be achieved by intense beams of heavy ions. (orig./HSI)

Flexible Aqueous Li-Ion Battery with High Energy and Power Densities.

Science.gov (United States)

Yang, Chongyin; Ji, Xiao; Fan, Xiulin; Gao, Tao; Suo, Liumin; Wang, Fei; Sun, Wei; Chen, Ji; Chen, Long; Han, Fudong; Miao, Ling; Xu, Kang; Gerasopoulos, Konstantinos; Wang, Chunsheng

2017-11-01

A flexible and wearable aqueous symmetrical lithium-ion battery is developed using a single LiVPO 4 F material as both cathode and anode in a "water-in-salt" gel polymer electrolyte. The symmetric lithium-ion chemistry exhibits high energy and power density and long cycle life, due to the formation of a robust solid electrolyte interphase consisting of Li 2 CO 3 -LiF, which enables fast Li-ion transport. Energy densities of 141 Wh kg -1 , power densities of 20 600 W kg -1 , and output voltage of 2.4 V can be delivered during >4000 cycles, which is far superior to reported aqueous energy storage devices at the same power level. Moreover, the full cell shows unprecedented tolerance to mechanical stress such as bending and cutting, where it not only does not catastrophically fail, as most nonaqueous cells would, but also maintains cell performance and continues to operate in ambient environment, a unique feature apparently derived from the high stability of the "water-in-salt" gel polymer electrolyte. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Damping-Growth Transition for Ion-Acoustic Waves in a Density Gradient

DEFF Research Database (Denmark)

D'Angelo, N.; Michelsen, Poul; Pécseli, Hans

1975-01-01

A damping-growth transition for ion-acoustic waves propagating in a nonuniform plasma (e-folding length for the density ln) is observed at a wavelength λ∼2πln. This result supports calculations performed in connection with the problem of heating of the solar corona by ion-acoustic waves generated...

Modification of high density polyethylene by gold implantation using different ion energies

Energy Technology Data Exchange (ETDEWEB)

Nenadović, M.; Potočnik, J. [INS Vinca, Laboratory of Atomic Physics, University of Belgrade, Mike Alasa 12–14, 11001 Belgrade (Serbia); Mitrić, M. [INS Vinca, Condensed Matter Physics Laboratory, University of Belgrade, Mike Alasa 12–14, 11001 Belgrade (Serbia); Štrbac, S. [ICTM Institute of Electrochemistry, University of Belgrade, Njegoseva 12, 11001 Belgrade (Serbia); Rakočević, Z., E-mail: zlatkora@vinca.rs [INS Vinca, Laboratory of Atomic Physics, University of Belgrade, Mike Alasa 12–14, 11001 Belgrade (Serbia)

2013-11-01

High density polyethylene (HDPE) samples were modified by Au{sup +} ion implantation at a dose of 5 × 10{sup 15} ions cm{sup −2}, using energies of 50, 100, 150 and 200 keV. The existence of implanted gold in the near-surface region of HDPE samples was confirmed by X-ray diffraction analysis. Surface roughness and Power Spectral Density analyses based on Atomic Force Microscopy (AFM) images of the surface topography revealed that the mechanism of HDPE modification during gold ion implantation depended on the energy of gold ions. Histograms obtained from phase AFM images indicated a qualitative change in the chemical composition of the surface during implantation with gold ions with different energies. Depth profiles obtained experimentally from cross-sectional Force Modulation Microscopy images and ones obtained from a theoretical simulation are in agreement for gold ions energies lower than 100 keV. The deviation that was observed for higher energies of the gold ions is explained by carbon precipitation in the near surface region of the HDPE, which prevented the penetration of gold ions further into the depth of the sample. - Highlights: • HDPE was implanted by Au{sup +} ions using energies of 50, 100, 150 and 200 keV. • Surface composition was analyzed from phase AFM images. • FMM depth profiles are in agreement with theoretical ones for energies up to 100 keV. • A deviation is observed for higher gold ion energies.

Modification of high density polyethylene by gold implantation using different ion energies

International Nuclear Information System (INIS)

Nenadović, M.; Potočnik, J.; Mitrić, M.; Štrbac, S.; Rakočević, Z.

2013-01-01

High density polyethylene (HDPE) samples were modified by Au + ion implantation at a dose of 5 × 10 15 ions cm −2 , using energies of 50, 100, 150 and 200 keV. The existence of implanted gold in the near-surface region of HDPE samples was confirmed by X-ray diffraction analysis. Surface roughness and Power Spectral Density analyses based on Atomic Force Microscopy (AFM) images of the surface topography revealed that the mechanism of HDPE modification during gold ion implantation depended on the energy of gold ions. Histograms obtained from phase AFM images indicated a qualitative change in the chemical composition of the surface during implantation with gold ions with different energies. Depth profiles obtained experimentally from cross-sectional Force Modulation Microscopy images and ones obtained from a theoretical simulation are in agreement for gold ions energies lower than 100 keV. The deviation that was observed for higher energies of the gold ions is explained by carbon precipitation in the near surface region of the HDPE, which prevented the penetration of gold ions further into the depth of the sample. - Highlights: • HDPE was implanted by Au + ions using energies of 50, 100, 150 and 200 keV. • Surface composition was analyzed from phase AFM images. • FMM depth profiles are in agreement with theoretical ones for energies up to 100 keV. • A deviation is observed for higher gold ion energies

Normal bone density in male pseudohermaphroditism due to 5a- reductase 2 deficiency

Directory of Open Access Journals (Sweden)

Costa Elaine Maria Frade

2001-01-01

Full Text Available Bone is an androgen-dependent tissue, but it is not clear whether the androgen action in bone depends on testosterone or on dihydrotestosterone. Patients with 5alpha-reductase 2 deficiency present normal levels of testosterone and low levels of dihydrotestosterone, providing an in vivo human model for the analysis of the effect of testosterone on bone. OBJECTIVE: To analyze bone mineral density in 4 adult patients with male pseudohermaphroditism due to 5alpha-reductase 2 deficiency. RESULTS: Three patients presented normal bone mineral density of the lumbar column (L1-L4 and femur neck, and the other patient presented a slight osteopenia in the lumbar column. CONCLUSION: Patients with dihydrotestosterone deficiency present normal bone mineral density, suggesting that dihydrotestosterone is not the main androgen acting in bone.

Modified Korteweg-deVries soliton evolution at critical density of negative ions in an inhomogeneous magnetized cold plasma

International Nuclear Information System (INIS)

Singh, Dhananjay K.; Malik, Hitendra K.

2007-01-01

Soliton propagation at critical density of negative ions is studied for weakly inhomogeneous magnetized cold plasma having positive ions, negative ions, and electrons. A general phase velocity relation is obtained and possible modes are studied for different cases involving different constituents of the plasma. Two types of modes (fast and slow) are found to propagate for the equal mass of the positive and negative ions. However, a limit on the obliqueness of magnetic field is obtained for the propagation of slow mode. For both types of modes, a variable coefficient modified Korteweg-deVries equation with an additional term arisen due to the density gradient is realized, which admits solutions for compressive solitons and rarefactive solitons of the same amplitudes at critical negative ion density. The propagation characteristics of these solitons are studied under the effect of densities of ions, magnetic field, and its obliqueness. The amplitudes of fast and slow wave solitons show their opposite behavior with the negative ion concentration, which is consistent with the variation of phase velocities with the negative ion density

Visualization and analysis of pulsed ion beam energy density profile with infrared imaging

Science.gov (United States)

Isakova, Y. I.; Pushkarev, A. I.

2018-03-01

Infrared imaging technique was used as a surface temperature-mapping tool to characterize the energy density distribution of intense pulsed ion beams on a thin metal target. The technique enables the measuring of the total ion beam energy and the energy density distribution along the cross section and allows one to optimize the operation of an ion diode and control target irradiation mode. The diagnostics was tested on the TEMP-4M accelerator at TPU, Tomsk, Russia and on the TEMP-6 accelerator at DUT, Dalian, China. The diagnostics was applied in studies of the dynamics of the target cooling in vacuum after irradiation and in the experiments with target ablation. Errors caused by the target ablation and target cooling during measurements have been analyzed. For Fluke Ti10 and Fluke Ti400 infrared cameras, the technique can achieve surface energy density sensitivity of 0.05 J/cm2 and spatial resolution of 1-2 mm. The thermal imaging diagnostics does not require expensive consumed materials. The measurement time does not exceed 0.1 s; therefore, this diagnostics can be used for the prompt evaluation of the energy density distribution of a pulsed ion beam and during automation of the irradiation process.

Moderate energy ions for high energy density physics experiments

International Nuclear Information System (INIS)

Grisham, L.R.

2004-01-01

This paper gives the results of a preliminary exploration of whether moderate energy ions (≅0.3-3 MeV/amu) could be useful as modest-cost drivers for high energy density physics experiments. It is found that if the target thickness is chosen so that the ion beam enters and then leaves the target in the vicinity of the peak of the dE/dX (stopping power) curve, high uniformity of energy deposition may be achievable while also maximizing the amount of energy per beam particle deposited within the target

A thermodynamic perturbation theory for the surface tension and ion density profile of a liquid metal

International Nuclear Information System (INIS)

Evans, R.; Kumaravadivel, R.

1976-01-01

A simple scheme for determining the ion density profile and the surface tension of a liquid metal is described. Assuming that the interaction between metallic pseudo-ions is of the form introduced by Evans, an approximate expression for the excess free energy of the system is derived using the thermodynamic perturbation theory of Weeks, Chandler and Anderson. This excess free energy is then minimized with respect to a parameter which specifies the ion density profile, and the surface tension is given directly. From a consideration of the dependence of the interionic forces on the electron density it is predicted that the ions should take up a very steep density profile at the liquid metal surface. This behaviour is contrasted with that to be expected for rare-gas fluids in which the interatomic forces are density-independent. The values of the surface tension calculated for liquid Na, K and Al from a simplified version of the theory are in reasonable agreement with experiment. (author)

Measurement of the density profile of pure and seeded molecular beams by femtosecond ion imaging

Energy Technology Data Exchange (ETDEWEB)

Meng, Congsen [LaserLaB Amsterdam, VU University Amsterdam, de Boelelaan 1083, 1081 HV Amsterdam (Netherlands); Department of Physics, National University of Defense Technology, Changsha 410073 (China); Janssen, Maurice H. M. [LaserLaB Amsterdam, VU University Amsterdam, de Boelelaan 1083, 1081 HV Amsterdam (Netherlands)

2015-02-15

Here, we report on femtosecond ion imaging experiments to measure the density profile of a pulsed supersonic molecular beam. Ion images are measured for both a molecular beam and bulk gas under identical experimental conditions via femtosecond multiphoton ionization of Xe atoms. We report the density profile of the molecular beam, and the measured absolute density is compared with theoretical calculations of the centre line beam density. Subsequently, we discuss reasons accounting for the differences between measurements and calculations and propose that strong skimmer interference is the most probable cause for the differences. Furthermore, we report on experiments measuring the centre line density of seeded supersonic beams. The femtosecond ion images show that seeding the heavy Xe atom at low relative seed fractions (1%-10%) in a light carrier gas like Ne results in strong relative enhancements of up to two orders of magnitude.

Energy dependence of ion-induced sputtering yields from monoatomic solids at normal incidence

International Nuclear Information System (INIS)

Yamamura, Yasunori; Tawara, Hiro.

1995-03-01

The yields of the ion-induced sputtering from monoatomic solids at normal incidence for various ion-target combinations are presented graphically as a function of the incident ion energy. In order to fill the lack of the experimental data, the sputtering yields are also calculated by the Monte Carlo simulation code ACAT for some ion-target combinations. Each graph shows available experimental data points and the ACAT data, together with the sputtering yields calculated by the present empirical formula, whose parameters are determined by the best-fit to available data. (author)

Ion-sound emission by Langmuir soliton reflected at density barrier

International Nuclear Information System (INIS)

El-Ashry, M.Y.

1989-07-01

The emission of ion-sound waves by an accelerated Langmuir soliton is studied. The acceleration of the soliton is due to an inhomogeneous density barrier. On the assumption that the kinetic energy of the Langmuir soliton is smaller than the potential energy created by the barrier. The basic equations describing the dynamic behaviour of the soliton and the emission of the ion-sound waves are formulated. The qualitative spatial distributions of the perturbed concentration in the ion-sound waves are analyzed at different characteristic points of the soliton. The energy lost by the soliton, as a result of the emission, is estimated. (author). 6 refs, 4 figs

Magnetically filtered Faraday probe for measuring the ion current density profile of a Hall thruster

International Nuclear Information System (INIS)

Rovey, Joshua L.; Walker, Mitchell L.R.; Gallimore, Alec D.; Peterson, Peter Y.

2006-01-01

The ability of a magnetically filtered Faraday probe (MFFP) to obtain the ion current density profile of a Hall thruster is investigated. The MFFP is designed to eliminate the collection of low-energy, charge-exchange (CEX) ions by using a variable magnetic field as an ion filter. In this study, a MFFP, Faraday probe with a reduced acceptance angle (BFP), and nude Faraday probe are used to measure the ion current density profile of a 5 kW Hall thruster operating over the range of 300-500 V and 5-10 mg/s. The probes are evaluated on a xenon propellant Hall thruster in the University of Michigan Large Vacuum Test Facility at operating pressures within the range of 4.4x10 -4 Pa Xe (3.3x10 -6 Torr Xe) to 1.1x10 -3 Pa Xe (8.4x10 -6 Torr Xe) in order to study the ability of the Faraday probe designs to filter out CEX ions. Detailed examination of the results shows that the nude probe measures a greater ion current density profile than both the MFFP and BFP over the range of angular positions investigated for each operating condition. The differences between the current density profiles obtained by each probe are attributed to the ion filtering systems employed. Analysis of the results shows that the MFFP, operating at a +5 A solenoid current, provides the best agreement with flight-test data and across operating pressures

Near equality of ion phase space densities at earth, Jupiter, and Saturn

Science.gov (United States)

Cheng, A. F.; Krimigis, S. M.; Armstrong, T. P.

1985-01-01

Energetic-ion phase-space density profiles are strikingly similar in the inner magnetospheres of earth, Jupiter, and Saturn for ions of first adiabatic invariant near 100 MeV/G and small mirror latitudes. Losses occur inside L approximately equal to 7 for Jupiter and Saturn and inside L approximately equal to 5 at earth. At these L values there exist steep plasma-density gradients at all three planets, associated with the Io plasma torus at Jupiter, the Rhea-Dione-Tethys torus at Saturn, and the plasmasphere at earth. Measurements of ion flux-tube contents at Jupiter and Saturn by the low-energy charged-particle experiment show that these are similar (for O ions at L = 5-9) to those at earth (for protons at L = 2-6). Furthermore, the thermal-ion flux-tube contents from Voyager plasma-science data at Jupiter and Saturn are also very nearly equal, and again similar to those at earth, differing by less than a factor of 3 at the respective L values. The near equality of energetic and thermal ion flux-tube contents at earth, Jupiter, and Saturn suggests the possibility of strong physical analogies in the interaction between plasma and energetic particles at the plasma tori/plasma sheets of Jupiter and Saturn and the plasmasphere of earth.

Low-density silicon thin films for lithium-ion battery anodes

Energy Technology Data Exchange (ETDEWEB)

Demirkan, M.T., E-mail: tmdemirkan@ualr.edu [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States); Department of Materials Science and Engineering, Gebze Technical University, Kocaeli (Turkey); Trahey, L. [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Karabacak, T. [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States)

2016-02-01

Density of sputter deposited silicon (Si) thin films was changed by a simple working gas pressure control process, and its effects on the cycling performance of Si films in Li-ion batteries as anodes was investigated. Higher gas pressure results in reduced film densities due to a shadowing effect originating from lower mean free path of sputter atoms, which leads to a wider angular distribution of the incoming flux and formation of a porous film microstructure. Si thin film anodes of different densities ranging from 2.27 g/cm{sup 3} (film porosity ~ 3%) down to 1.64 g/cm{sup 3} (~ 30% porosity) were fabricated by magnetron sputtering at argon pressures varying from 0.2 Pa to 2.6 Pa, respectively. High density Si thin film anodes of 2.27 g/cm{sup 3} suffered from an unstable cycling behavior during charging/discharging depicted by a continuous reduction in specific down to ~ 830 mAh/g at the 100th cycle. Electrochemical properties of lower density films with 1.99 g/cm{sup 3} (~ 15% porosity) and 1.77 g/cm{sup 3} (~ 24% porosity) got worse resulting in only ~ 100 mAh/g capacity at 100th cycle. On the other hand, as the density of anode was further reduced down to about 1.64 g/cm{sup 3} (~ 30% porosity), cycling stability and capacity retention significantly improved resulting in specific capacity values ~ 650 mAh/g at 100th cycle with coulombic efficiencies of > 98%. Enhancement in our low density Si film anodes are believed to mainly originate from the availability of voids for volumetric expansion during lithiation and resulting compliant behavior that provides superior mechanical and electrochemical stability. - Highlights: • Low density Si thin films were studied as Li-ion battery anodes. • Low density Si films were fabricated by magnetron sputter deposition. • Density of Si films reduced down to as low as ~ 1.64 g/cm{sup 3} with a porosity of ~ 30% • Low density Si films presented superior mechanical properties during cycling.

High Energy Density Li-Ion Batteries Designed for Low Temperature Applications, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The state-of-the-art Li-ion batteries do not fully meet the energy density, power density and safety requirements specified by NASA for future exploration missions....

Effects of positron density and temperature on large amplitude ion-acoustic waves in an electron-positron-ion plasma

International Nuclear Information System (INIS)

Nejoh, Y.N.

1997-01-01

The nonlinear wave structures of large amplitude ion-acoustic waves are studied in a plasma with positrons. We have presented the region of existence of the ion-acoustic waves by analysing the structure of the pseudopotential. The region of existence sensitively depends on the positron to electron density ratio, the ion to electron mass ratio and the positron to electron temperature ratio. It is shown that the maximum Mach number increases as the positron temperature increases and the region of existence of the ion-acoustic waves spreads as the positron temperature increases. 12 refs., 6 figs

A Quasi-Solid-State Sodium-Ion Capacitor with High Energy Density.

Science.gov (United States)

Wang, Faxing; Wang, Xiaowei; Chang, Zheng; Wu, Xiongwei; Liu, Xiang; Fu, Lijun; Zhu, Yusong; Wu, Yuping; Huang, Wei

2015-11-18

A quasi-solid-state sodium-ion capacitor is demonstrated with nanoporous disordered carbon and macroporous graphene as the negative and positive electrodes, respectively, using a sodium-ion-conducting gel polymer electrolyte. It can operate at a cell voltage as high as 4.2 V with an energy density of record high 168 W h kg(-1). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Calculation of large ion densities under HVdc transmission lines by the finite difference method

International Nuclear Information System (INIS)

Suda, Tomotaka; Sunaga, Yoshitaka

1995-01-01

A calculation method for large ion densities (charged aerosols) under HVdc transmission lines was developed considering both the charging mechanism of aerosols by small ions and the drifting process by wind. Large ion densities calculated by this method agreed well with the ones measured under the Shiobara HVdc test line on the lateral profiles at ground level up to about 70m downwind from the line. Measured values decreased more quickly than calculated ones farther downwind from the line. Considering the effect of point discharge from ground cover (earth corona) improved the agreement in the farther downwind region

Characterization of the internal ion environment of biofilms based on charge density and shape of ion.

Science.gov (United States)

Kurniawan, Andi; Tsuchiya, Yuki; Eda, Shima; Morisaki, Hisao

2015-12-01

Biofilm polymers contain both electrically positively and negatively charged sites. These charged sites enable the biofilm to trap and retain ions leading to an important role of biofilm such as nutrient recycling and pollutant purification. Much work has focused on the ion-exchange capacity of biofilms, and they are known to adsorb ions through an exchange mechanism between the ions in solution and the ions adsorbed to the charged sites on the biofilm polymer. However, recent studies suggest that the adsorption/desorption behavior of ions in a biofilm cannot be explained solely by this ion exchange mechanism. To examine the possibility that a substantial amount of ions are held in the interstitial region of the biofilm polymer by an electrostatic interaction, intact biofilms formed in a natural environment were immersed in distilled water and ion desorption was investigated. All of the detected ion species were released from the biofilms over a short period of time, and very few ions were subsequently released over more time, indicating that the interstitial region of biofilm polymers is another ion reserve. The extent of ion retention in the interstitial region of biofilms for each ion can be determined largely by charge density, |Z|/r, where |Z| is the ion valence as absolute value and r is the ion radius. The higher |Z|/r value an ion has, the stronger it is retained in the interstitial region of biofilms. Ion shape is also a key determinant of ion retention. Spherical and non-spherical ions have different correlations between the condensation ratio and |Z|/r. The generality of these findings were assured by various biofilm samples. Thus, the internal regions of biofilms exchange ions dynamically with the outside environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Foldable, High Energy Density Lithium Ion Batteries

Science.gov (United States)

Suresh, Shravan

Lithium Ion Batteries (LIBs) have become ubiquitous owing to its low cost, high energy density and, power density. Due to these advantages, LIBs have garnered a lot of attention as the primary energy storage devices in consumer electronics and electric vehicles. Recent advances in the consumer electronics research and, the drive to reduce greenhouse gases have created a demand for a shape conformable, high energy density batteries. This thesis focuses on the aforementioned two aspects of LIBs: (a) shape conformability (b) energy density and provides potential solutions to enhance them. This thesis is divided into two parts viz. (i) achieving foldability in batteries and, (ii) improving its energy density. Conventional LIBs are not shape conformable due to two limitations viz. inelasticity of metallic foils, and delamination of the active materials while bending. In the first part of the thesis (in Chapter 3), this problem is solved by replacing metallic current collector with Carbon Nanotube Macrofilms (CNMs). CNMs are superelastic films comprising of porous interconnected nanotube network. Using Molecular Dynamics (MD) simulation, we found that in the presence of an interconnected nanotube network CNMs can be fully folded. This is because the resultant stress due to bending and, the effective bending angle at the interface is reduced due to the network of nanotubes. Hence, unlike an isolated nanotube (which ruptures beyond 120 degrees of bending), a network of nanotubes can be completely folded. Thus, by replacing metallic current collector foils with CNMs, the flexibility limitation of a conventional LIB can be transcended. The second part of this thesis focusses on enhancing the energy density of LIBs. Two strategies adopted to achieve this goal are (a) removing the dead weight of the batteries, and (b) incorporating high energy density electrode materials. By incorporating CNMs, the weight of the batteries was reduced by 5-10 times due to low mass loading of

High dislocation density structures and hardening produced by high fluency pulsed-ion-beam implantation

International Nuclear Information System (INIS)

Sharkeev, Yu.P.; Didenko, A.N.; Kozlov, E.V.

1994-01-01

The paper presents a review of experimental data on the ''long-range effect'' (a change in dislocation structure and in physicomechanical properties at distances considerably greater than the ion range value in ion-implanted metallic materials and semiconductors). Our results of electron microscopy studies of high density dislocation structure in ion-implanted metallic materials with different initial states are given. It has been shown that the nature of the dislocation structure and its quantitative characteristics in the implanted metals and alloys depend on the target initial state, the ion type and energy and the retained dose. The data obtained by different workers are in good agreement both with our results and with each other as well as with the results of investigation of macroscopic characteristics (wear resistance and microhardness). It has been established that the ''long-range effect'' occurs in metallic materials with a low yield point or high plasticity level and with little dislocation density in their initial state prior to ion implantation. ((orig.))

Ultralow energy ion beam surface modification of low density polyethylene.

Science.gov (United States)

Shenton, Martyn J; Bradley, James W; van den Berg, Jaap A; Armour, David G; Stevens, Gary C

2005-12-01

Ultralow energy Ar+ and O+ ion beam irradiation of low density polyethylene has been carried out under controlled dose and monoenergetic conditions. XPS of Ar+-treated surfaces exposed to ambient atmosphere show that the bombardment of 50 eV Ar+ ions at a total dose of 10(16) cm(-2) gives rise to very reactive surfaces with oxygen incorporation at about 50% of the species present in the upper surface layer. Using pure O+ beam irradiation, comparatively low O incorporation is achieved without exposure to atmosphere (approximately 13% O in the upper surface). However, if the surface is activated by Ar+ pretreatment, then large oxygen contents can be achieved under subsequent O+ irradiation (up to 48% O). The results show that for very low energy (20 eV) oxygen ions there is a dose threshold of about 5 x 10(15) cm(-2) before surface oxygen incorporation is observed. It appears that, for both Ar+ and O+ ions in this regime, the degree of surface modification is only very weakly dependent on the ion energy. The results suggest that in the nonequilibrium plasma treatment of polymers, where the ion flux is typically 10(18) m(-2) s(-1), low energy ions (<50 eV) may be responsible for surface chemical modification.

Electrostatic lens to focus an ion beam to uniform density

International Nuclear Information System (INIS)

Johnson, C.H.

1977-01-01

A focusing lens for an ion beam having a gaussian or similar density profile is described. The lens is constructed to provide an inner zero electrostatic field, and an outer electrostatic field such that ions entering this outer field are deflected by an amount that is a function of their distance from the edge of the inner field. The result is a beam that focuses to uniform density in a manner analogous to that of an optical ring lens. In one embodiment, a conically-shaped network of fine wires is enclosed within a cylindrical anode. The wire net together with the anode produces a voltage field that re-directs the outer particles of the beam while the axial particles pass undeflected through a zero field inside the wire net. The result is a focused beam having a uniform intensity over a given target area and at a given distance from the lens

Ultrahigh-Energy Density Lithium-Ion Cable Battery Based on the Carbon-Nanotube Woven Macrofilms.

Science.gov (United States)

Wu, Ziping; Liu, Kaixi; Lv, Chao; Zhong, Shengwen; Wang, Qinghui; Liu, Ting; Liu, Xianbin; Yin, Yanhong; Hu, Yingyan; Wei, Di; Liu, Zhongfan

2018-05-01

Moore's law predicts the performance of integrated circuit doubles every two years, lasting for more than five decades. However, the improvements of the performance of energy density in batteries lag far behind that. In addition, the poor flexibility, insufficient-energy density, and complexity of incorporation into wearable electronics remain considerable challenges for current battery technology. Herein, a lithium-ion cable battery is invented, which is insensitive to deformation due to its use of carbon nanotube (CNT) woven macrofilms as the charge collectors. An ultrahigh-tap density of 10 mg cm -2 of the electrodes can be obtained, which leads to an extremely high-energy density of 215 mWh cm -3 . The value is approximately seven times than that of the highest performance reported previously. In addition, the battery displays very stable rate performance and lower internal resistance than conventional lithium-ion batteries using metal charge collectors. Moreover, it demonstrates excellent convenience for connecting electronics as a new strategy is applied, in which both electrodes can be integrated into one end by a CNT macrorope. Such an ultrahigh-energy density lithium-ion cable battery provides a feasible way to power wearable electronics with commercial viability. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Unique aqueous Li-ion/sulfur chemistry with high energy density and reversibility.

Science.gov (United States)

Yang, Chongyin; Suo, Liumin; Borodin, Oleg; Wang, Fei; Sun, Wei; Gao, Tao; Fan, Xiulin; Hou, Singyuk; Ma, Zhaohui; Amine, Khalil; Xu, Kang; Wang, Chunsheng

2017-06-13

Leveraging the most recent success in expanding the electrochemical stability window of aqueous electrolytes, in this work we create a unique Li-ion/sulfur chemistry of both high energy density and safety. We show that in the superconcentrated aqueous electrolyte, lithiation of sulfur experiences phase change from a high-order polysulfide to low-order polysulfides through solid-liquid two-phase reaction pathway, where the liquid polysulfide phase in the sulfide electrode is thermodynamically phase-separated from the superconcentrated aqueous electrolyte. The sulfur with solid-liquid two-phase exhibits a reversible capacity of 1,327 mAh/(g of S), along with fast reaction kinetics and negligible polysulfide dissolution. By coupling a sulfur anode with different Li-ion cathode materials, the aqueous Li-ion/sulfur full cell delivers record-high energy densities up to 200 Wh/(kg of total electrode mass) for >1,000 cycles at ∼100% coulombic efficiency. These performances already approach that of commercial lithium-ion batteries (LIBs) using a nonaqueous electrolyte, along with intrinsic safety not possessed by the latter. The excellent performance of this aqueous battery chemistry significantly promotes the practical possibility of aqueous LIBs in large-format applications.

HIGH ENERGY DENSITY PHYSICS EXPERIMENTS WITH INTENSE HEAVY ION BEAMS

International Nuclear Information System (INIS)

Bieniosek, F.M.; Henestroza, E.; Leitner, M.; Logan, B.G.; More, R.M.; Roy, P.K.; Ni, P.; Seidl, P.A.; Waldron, W.L.; Barnard, J.J.

2008-01-01

The US heavy ion fusion science program has developed techniques for heating ion-beam-driven warm dense matter (WDM) targets. The WDM conditions are to be achieved by combined longitudinal and transverse space-charge neutralized drift compression of the ion beam to provide a hot spot on the target with a beam spot size of about 1 mm, and pulse length about 1-2 ns. As a technique for heating volumetric samples of matter to high energy density, intense beams of heavy ions are capable of delivering precise and uniform beam energy deposition dE/dx, in a relatively large sample size, and the ability to heat any solid-phase target material. Initial experiments use a 0.3 MeV K+ beam (below the Bragg peak) from the NDCX-I accelerator. Future plans include target experiments using the NDCX-II accelerator, which is designed to heat targets at the Bragg peak using a 3-6 MeV lithium ion beam. The range of the beams in solid matter targets is about 1 micron, which can be lengthened by using porous targets at reduced density. We have completed the fabrication of a new experimental target chamber facility for WDM experiments, and implemented initial target diagnostics to be used for the first target experiments in NDCX-1. The target chamber has been installed on the NDCX-I beamline. The target diagnostics include a fast multi-channel optical pyrometer, optical streak camera, VISAR, and high-speed gated cameras. Initial WDM experiments will heat targets by compressed NDCX-I beams and will explore measurement of temperature and other target parameters. Experiments are planned in areas such as dense electronegative targets, porous target homogenization and two-phase equation of state

Pseudoclassical approach to electron and ion density correlations in simple liquid metals

International Nuclear Information System (INIS)

Vericat, F.; Tosi, M.P.; Pastore, G.

1986-04-01

Electron-electron and electron-ion structural correlations in simple liquid metals are treated by using effective pair potentials to incorporate quantal effects into a pseudoclassical description of the electron fluid. An effective pair potential between simultaneous electron density fluctuations is first constructed from known properties of the degenerate jellium model, which are the plasmon sum rule, the Kimball-Niklasson relation and Yasuhara's values of the electron pair distribution function at contact. An analytic expression is thereby obtained in the Debye-Hueckel approximation for the electronic structure factor in jellium over a range of density appropriate to metals, with results which compare favourably with those of fully quantal evaluations. A simple pseudoclassical model is then set up for a liquid metal: this involves a model of charged hard spheres for the ion-ion potential and an empty core model for the electron-ion potential, the Coulombic tails being scaled as required by the relation between the long-wavelength partial structure factors and the isothermal compressibility of the metal. The model is solved analytically by a pseudoclassical linear response treatment of the electron-ion coupling and numerical results are reported for partial structure factors in liquid sodium and liquid beryllium. Contact is made for the latter system with data on the electron-electron structure factor in the crystal from inelastic X-ray scattering experiments of Eisenberger, Marra and Brown. (author)

Comparison of ion temperature and ion density measured during geomagnetically very quiet conditions on board of the geophysical rocket ''Vertical-6'' with the international reference ionosphere

International Nuclear Information System (INIS)

Bencze, P.; Kovacs, K.; Apathy, I.; Szemerey, I.; Afonin, V.; Bezrukih, V.; Shutte, N.

1980-05-01

Ion temperature and ion density, measured on October 25, 1977 during the flight of the geophyisical rocket ''Vertical-6'' by means of a group of five retarding potential analyzers looking into different directions of space, are compared with the International Reference Ionosphere 1978. The measurements were carried out in a geomagnetically quiet period to a height of 1500 km. The results show that both the ion temperature and the ion density are lower than the values predicted by the Reference Ionosphere, the difference is decreasing with increasing altitude. (author)

Kinetic Alfven wave with density variation and loss-cone distribution function of multi-ions in PSBL region

Science.gov (United States)

Tamrakar, Radha; Varma, P.; Tiwari, M. S.

2018-05-01

Kinetic Alfven wave (KAW) generation due to variation of loss-cone index J and density of multi-ions (H+, He+ and O+) in the plasma sheet boundary layer region (PSBL) is investigated. Kinetic approach is used to derive dispersion relation of wave using Vlasov equation. Variation of frequency with respect to wide range of k⊥ρi (where k⊥ is wave vector across the magnetic field, ρi is gyroradius of ions and i denotes H+, He+ and O+ ions) is analyzed. It is found that each ion gyroradius and number density shows different effect on wave generation with varying width of loss-cone. KAW is generated with multi-ions (H+, He+ and O+) over wide regime for J=1 and shows dissimilar effect for J=2. Frequency is reduced with increasing density of gyrating He+ and O+ ions. Wave frequency is obtained within the reported range which strongly supports generation of kinetic Alfven waves. A sudden drop of frequency is also observed for H+ and He+ ion which may be due to heavy penetration of these ions through the loss-cone. The parameters of PSBL region are used for numerical calculation. The application of these results are in understanding the effect of gyrating multi-ions in transfer of energy and Poynting flux losses from PSBL region towards ionosphere and also describing the generation of aurora.

Investigation of the alpha cluster model and the density matrix expansion in ion-ion collision

International Nuclear Information System (INIS)

Rashdan, M.B.M.

1986-01-01

This thesis deals with the investigation of the alpha cluster model (ACM) of brink and studies of the accuracy of the density matrix expansion (DME) approximation in deriving the real part of the ion-ion optical potential. the ACM is applied to calculate the inelastic 0 1 + →2 1 + charge form factor for electron scattering by 12 C to investigate the validity of this model for 12 C nucleus. it is found that the experimental curve can be fitted over the entire range of the momentum transfer by a generator - coordinate state for the 2 1 + state that consist of a superposition of two triangular ACM states with two different cluster separations and the same oscillator parameter

DIAGNOSTICS FOR ION BEAM DRIVEN HIGH ENERGY DENSITY PHYSICS EXPERIMENTS

International Nuclear Information System (INIS)

Bieniosek, F.M.; Henestroza, E.; Lidia, S.; Ni, P.A.

2010-01-01

Intense beams of heavy ions are capable of heating volumetric samples of matter to high energy density. Experiments are performed on the resulting warm dense matter (WDM) at the NDCX-I ion beam accelerator. The 0.3 MeV, 30-mA K + beam from NDCX-I heats foil targets by combined longitudinal and transverse neutralized drift compression of the ion beam. Both the compressed and uncompressed parts of the NDCX-I beam heat targets. The exotic state of matter (WDM) in these experiments requires specialized diagnostic techniques. We have developed a target chamber and fielded target diagnostics including a fast multi-channel optical pyrometer, optical streak camera, laser Doppler-shift interferometer (VISAR), beam transmission diagnostics, and high-speed gated cameras. We also present plans and opportunities for diagnostic development and a new target chamber for NDCX-II.

Ion acceleration in electrostatic collisionless shock: on the optimal density profile for quasi-monoenergetic beams

Science.gov (United States)

Boella, E.; Fiúza, F.; Stockem Novo, A.; Fonseca, R.; Silva, L. O.

2018-03-01

A numerical study on ion acceleration in electrostatic shock waves is presented, with the aim of determining the best plasma configuration to achieve quasi-monoenergetic ion beams in laser-driven systems. It was recently shown that tailored near-critical density plasmas characterized by a long-scale decreasing rear density profile lead to beams with low energy spread (Fiúza et al 2012 Phys. Rev. Lett. 109 215001). In this work, a detailed parameter scan investigating different plasma scale lengths is carried out. As result, the optimal plasma spatial scale length that allows for minimizing the energy spread while ensuring a significant reflection of ions by the shock is identified. Furthermore, a new configuration where the required profile has been obtained by coupling micro layers of different densities is proposed. Results show that this new engineered approach is a valid alternative, guaranteeing a low energy spread with a higher level of controllability.

Studies on the production of high energy density in matter with intense heavy-ion beams

International Nuclear Information System (INIS)

Jacoby, J.

1989-01-01

In the framework of the present thesis the interaction of an intense heavy-ion beam with a small, but macroscopic, amount of matter is studied. Thereby high energy densities are produced in the target matter. For this experiment it was for the first time possible to heat matter with ion beams from conventional heavy-ion accelerators up to plasma conditions. A Kr + ion beam was first accelerated with the heavy-ion accelerator MAXILAC to 45 keV/u and then focused by a fine-focusing lens on a closed xenon gas target. The light emitted from the target was space- and time-resolved taken up with a spectrometer as well a streak and CCD camera. Thereby the radial development of the plasma and the penetration behaviour of the ion beam were consecuted. The free-electron density of the plasma was determined from the Stark-broadening of emission lines (n e ≅ 4x10 16 cm -3 ). The electron temperature amounted in the center of the pipelet kT ≅ 0.75 eV. (orig./HSI) [de

Body fat assessed from body density and estimated from skinfold thickness in normal children and children with cystic fibrosis.

Science.gov (United States)

Johnston, J L; Leong, M S; Checkland, E G; Zuberbuhler, P C; Conger, P R; Quinney, H A

1988-12-01

Body density and skinfold thickness at four sites were measured in 140 normal boys, 168 normal girls, and 6 boys and 7 girls with cystic fibrosis, all aged 8-14 y. Prediction equations for the normal boys and girls for the estimation of body-fat content from skinfold measurements were derived from linear regression of body density vs the log of the sum of the skinfold thickness. The relationship between body density and the log of the sum of the skinfold measurements differed from normal for the boys and girls with cystic fibrosis because of their high body density even though their large residual volume was corrected for. However the sum of skinfold measurements in the children with cystic fibrosis did not differ from normal. Thus body fat percent of these children with cystic fibrosis was underestimated when calculated from body density and invalid when calculated from skinfold thickness.

Electron density measurements during ion beam transport on Gamble II

International Nuclear Information System (INIS)

Weber, B.V.; Hinshelwood, D.D.; Neri, J.M.; Ottinger, P.F.; Rose, D.V.; Stephanakis, S.J.; Young, F.C.

1999-01-01

High-sensitivity laser interferometry was used to measure the electron density created when an intense proton beam (100 kA, 1 MeV, 50 ns) from the Gamble II generator was transported through low-pressure gas as part of a project investigating Self-Pinched Transport (SPT) of intense ion beams. This measurement is non-perturbing and sufficiently quantitative to allow benchmarking of codes (particularly IPROP) used to model beam-gas interaction and ion-beam transport. Very high phase sensitivity is required for this measurement. For example, a 100-kA, 1-MeV, 10-cm-radius proton beam with uniform current density has a line-integrated proton density equal to n b L = 3 x 10 13 cm -2 . An equal electron line-density, n e L = n b L, (expected for transport in vacuum) will be detected as a phase shift of the 1.064 microm laser beam of only 0.05degree, or an optical path change of 1.4 x 10 -4 waves (about the size of a hydrogen atom). The time-history of the line-integrated electron density, measured across a diameter of the transport chamber at 43 cm from the input aperture, starts with the proton arrival time and decays differently depending on the gas pressure. The gas conditions included vacuum (10 -4 Torr air), 30 to 220 mTorr He, and 1 Torr air. The measured densities vary by three orders of magnitude, from 10 13 to 10 16 cm -2 for the range of gas pressures investigated. In vacuum, the measured electron densities indicate only co-moving electrons (n e L approximately n b L). In He, when the gas pressure is sufficient for ionization by beam particles and SPT is observed, n e L increases to about 10 n b L. At even higher pressures where electrons contribute to ionization, even higher electron densities are observed with an ionization fraction of about 2%. The diagnostic technique as used on the SPT experiment will be described and a summary of the results will be given. The measurements are in reasonable agreement with theoretical predictions from the IPROP code

Study of the ion density of a radio-frequency plasma using electrostatic probes and focussed microwave interferometers

International Nuclear Information System (INIS)

Nguyen Cao, L.; Gagne, R.R.J.

1976-01-01

In order to verify experimentally and compare recent ion theories for cylindrical electrostatic probes, the ion density in a radio-frequency plasma was evaluated from V-I curves by means of six different theories. At low pressures, the theories of Bernstein and Rabinowitz, of Lam and Laframboise, give values of density which differ respectively by 20, 25 and 30% compared with the values obtained using a 10GHz focussed microwave interferometer. At the continuum limit, The Schulz and Brown's, and Su and Kiel's theories give density values which disagree respectively by 55 and 20%, compared with the values obtained by microwaves. For pressures varying from 0.05 to 3mmHg, the decrease of ion current, as predicted theorically by Waymouth, was observed. The density perturbation near the probe was found to be a dominant factor affecting the precision of density measurements, for pressures up to 2mmHg at least for our experimental conditions [fr

Mineral density volume gradients in normal and diseased human tissues.

Directory of Open Access Journals (Sweden)

Sabra I Djomehri

Full Text Available Clinical computed tomography provides a single mineral density (MD value for heterogeneous calcified tissues containing early and late stage pathologic formations. The novel aspect of this study is that, it extends current quantitative methods of mapping mineral density gradients to three dimensions, discretizes early and late mineralized stages, identifies elemental distribution in discretized volumes, and correlates measured MD with respective calcium (Ca to phosphorus (P and Ca to zinc (Zn elemental ratios. To accomplish this, MD variations identified using polychromatic radiation from a high resolution micro-computed tomography (micro-CT benchtop unit were correlated with elemental mapping obtained from a microprobe X-ray fluorescence (XRF using synchrotron monochromatic radiation. Digital segmentation of tomograms from normal and diseased tissues (N=5 per group; 40-60 year old males contained significant mineral density variations (enamel: 2820-3095 mg/cc, bone: 570-1415 mg/cc, cementum: 1240-1340 mg/cc, dentin: 1480-1590 mg/cc, cementum affected by periodontitis: 1100-1220 mg/cc, hypomineralized carious dentin: 345-1450 mg/cc, hypermineralized carious dentin: 1815-2740 mg/cc, and dental calculus: 1290-1770 mg/cc. A plausible linear correlation between segmented MD volumes and elemental ratios within these volumes was established, and Ca/P ratios for dentin (1.49, hypomineralized dentin (0.32-0.46, cementum (1.51, and bone (1.68 were observed. Furthermore, varying Ca/Zn ratios were distinguished in adapted compared to normal tissues, such as in bone (855-2765 and in cementum (595-990, highlighting Zn as an influential element in prompting observed adaptive properties. Hence, results provide insights on mineral density gradients with elemental concentrations and elemental footprints that in turn could aid in elucidating mechanistic processes for pathologic formations.

Mineral Density Volume Gradients in Normal and Diseased Human Tissues

Science.gov (United States)

Djomehri, Sabra I.; Candell, Susan; Case, Thomas; Browning, Alyssa; Marshall, Grayson W.; Yun, Wenbing; Lau, S. H.; Webb, Samuel; Ho, Sunita P.

2015-01-01

Clinical computed tomography provides a single mineral density (MD) value for heterogeneous calcified tissues containing early and late stage pathologic formations. The novel aspect of this study is that, it extends current quantitative methods of mapping mineral density gradients to three dimensions, discretizes early and late mineralized stages, identifies elemental distribution in discretized volumes, and correlates measured MD with respective calcium (Ca) to phosphorus (P) and Ca to zinc (Zn) elemental ratios. To accomplish this, MD variations identified using polychromatic radiation from a high resolution micro-computed tomography (micro-CT) benchtop unit were correlated with elemental mapping obtained from a microprobe X-ray fluorescence (XRF) using synchrotron monochromatic radiation. Digital segmentation of tomograms from normal and diseased tissues (N=5 per group; 40-60 year old males) contained significant mineral density variations (enamel: 2820-3095mg/cc, bone: 570-1415mg/cc, cementum: 1240-1340mg/cc, dentin: 1480-1590mg/cc, cementum affected by periodontitis: 1100-1220mg/cc, hypomineralized carious dentin: 345-1450mg/cc, hypermineralized carious dentin: 1815-2740mg/cc, and dental calculus: 1290-1770mg/cc). A plausible linear correlation between segmented MD volumes and elemental ratios within these volumes was established, and Ca/P ratios for dentin (1.49), hypomineralized dentin (0.32-0.46), cementum (1.51), and bone (1.68) were observed. Furthermore, varying Ca/Zn ratios were distinguished in adapted compared to normal tissues, such as in bone (855-2765) and in cementum (595-990), highlighting Zn as an influential element in prompting observed adaptive properties. Hence, results provide insights on mineral density gradients with elemental concentrations and elemental footprints that in turn could aid in elucidating mechanistic processes for pathologic formations. PMID:25856386

Effect of radical species density and ion bombardment during ashing of extreme ultralow-κ interlevel dielectric materials

International Nuclear Information System (INIS)

Worsley, M. A.; Bent, S. F.; Fuller, N. C. M.; Tai, T. L.; Doyle, J.; Rothwell, M.; Dalton, T.

2007-01-01

The significance of ion impact and radical species density on ash-induced modification of an extreme ultralow-κ interlevel dielectric (ILD) material (κ 2 and Ar/N 2 dual frequency capacitive discharges is determined by combining plasma diagnostics, modeling of the ion angular distribution function, and material characterization such as angle resolved x-ray photoelectron spectroscopy. Radical species density was determined by optical emission actinometry under the same conditions and in the same reactor in a previous study by the present authors. ILD modification is observed and correlated with changes in the plasma for a range of pressures (5-60 mTorr), bias powers (0-350 W), and percent Ar in the source gas (0%, 85%). For the Ar/O 2 discharge, extensive modification of the ILD sidewall was observed for significant ion scattering conditions, whereas minimal modification of the ILD sidewall was observed under conditions of minimal or no ion scattering. Further, for an identical increase in the O-radical density (∼ an order of magnitude), a different degree of modification was induced at the ILD trench bottom surface depending on whether pressure or percent Ar was used to increase the radical density. The different degrees of modification seemingly correlated with the relative changes in the ion current for increasing pressure or percent Ar. For the Ar/N 2 discharge, reduced damage of the ILD sidewall and trench bottom surfaces was observed for increasing pressure (increasing N-radical density) and decreasing ion current to both surfaces. It is, thus, proposed that the mechanism for modification of the porous ILD is dominated by the creation of reactive sites by ion impact under the present conditions. A detailed discussion of the results which support this proposal is presented

Remote sensing of electron density and ion composition using nonducted whistler observations on OGO 1 and Van Allen Probes

Science.gov (United States)

Sonwalkar, V. S.; Butler, J.; Reddy, A.

2017-12-01

We present a new method to remotely measure magnetospheric electron density and ion composition using lightning generated nonducted whistlers observed on a satellite. Electron and ion densities play important roles in magnetospheric processes such as wave-particle interactions in the equatorial region and ion-neutral dynamics in the ionosphere, and are important for calculating space weather effects such as particle precipitation, GPS scintillations, and satellite drag. The nonducted whistler resulting from a single lightning appears on a spectrogram as a series of magnetospherically reflected traces with characteristic dispersion (time delay versus frequency) and upper and lower cut off frequencies. Ray tracing simulations show that these observed characteristics depend on the magnetospheric electron density and ion composition. The cut off frequencies depend on both electron density and ion composition. The dispersion depends strongly on electron density, but weakly on ion composition. Using an iterative process to fit the measured dispersion and cutoff frequencies to those obtained from ray tracing simulations, it is possible to construct the electron and ion density profiles of the magnetosphere. We demonstrate our method by applying it to nonducted whistlers observed on OGO 1 and Van Allen probe satellites. In one instance (08 Nov 1965), whistler traces observed on OGO 1 (L = 2.4, λm = -6°) displayed a few seconds of dispersion and cutoff frequencies in the 1-10 kHz range. Ray tracing analysis showed that a diffusive equilibrium density model with the following parameters can reproduce the observed characteristics of the whistler traces: 1900 el/cc at L=2.4 and the equator, 358,000 el/cc at F2 peak (hmF2 = 220 km), the relative ion concentrations αH+ = 0.2, αHe+ = 0.2, and αO+ = 0.6 at 1000 km, and temperature 1600 K. The method developed here can be applied to whistlers observed on the past, current, and future magnetospheric satellite missions carrying

Flexible Aqueous Lithium-Ion Battery with High Safety and Large Volumetric Energy Density.

Science.gov (United States)

Dong, Xiaoli; Chen, Long; Su, Xiuli; Wang, Yonggang; Xia, Yongyao

2016-06-20

A flexible and wearable aqueous lithium-ion battery is introduced based on spinel Li1.1 Mn2 O4 cathode and a carbon-coated NASICON-type LiTi2 (PO4 )3 anode (NASICON=sodium-ion super ionic conductor). Energy densities of 63 Wh kg(-1) or 124 mWh cm(-3) and power densities of 3 275 W kg(-1) or 11.1 W cm(-3) can be obtained, which are seven times larger than the largest reported till now. The full cell can keep its capacity without significant loss under different bending states, which shows excellent flexibility. Furthermore, two such flexible cells in series with an operation voltage of 4 V can be compatible with current nonaqueous Li-ion batteries. Therefore, such a flexible cell can potentially be put into practical applications for wearable electronics. In addition, a self-chargeable unit is realized by integrating a single flexible aqueous Li-ion battery with a commercial flexible solar cell, which may facilitate the long-time outdoor operation of flexible and wearable electronic devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanomaterials Enabled High Energy and Power Density Li-ion Batteries, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — There is a need for high energy (~ 200 Wh/kg) and high power (> 500 W/kg) density rechargeable Li-ion batteries that are safe and reliable for several space and...

Signs of Gas Trapping in Normal Lung Density Regions in Smokers.

Science.gov (United States)

Bodduluri, Sandeep; Reinhardt, Joseph M; Hoffman, Eric A; Newell, John D; Nath, Hrudaya; Dransfield, Mark T; Bhatt, Surya P

2017-12-01

A substantial proportion of subjects without overt airflow obstruction have significant respiratory morbidity and structural abnormalities as visualized by computed tomography. Whether regions of the lung that appear normal using traditional computed tomography criteria have mild disease is not known. To identify subthreshold structural disease in normal-appearing lung regions in smokers. We analyzed 8,034 subjects with complete inspiratory and expiratory computed tomographic data participating in the COPDGene Study, including 103 lifetime nonsmokers. The ratio of the mean lung density at end expiration (E) to end inspiration (I) was calculated in lung regions with normal density (ND) by traditional thresholds for mild emphysema (-910 Hounsfield units) and gas trapping (-856 Hounsfield units) to derive the ND-E/I ratio. Multivariable regression analysis was used to measure the associations between ND-E/I, lung function, and respiratory morbidity. The ND-E/I ratio was greater in smokers than in nonsmokers, and it progressively increased from mild to severe chronic obstructive pulmonary disease severity. A proportion of 26.3% of smokers without airflow obstruction had ND-E/I greater than the 90th percentile of normal. ND-E/I was independently associated with FEV 1 (adjusted β = -0.020; 95% confidence interval [CI], -0.032 to -0.007; P = 0.001), St. George's Respiratory Questionnaire scores (adjusted β = 0.952; 95% CI, 0.529 to 1.374; P smokers without airflow obstruction, and it is associated with respiratory morbidity. Clinical trial registered with www.clinicaltrials.gov (NCT00608764).

Measurement of the density profile of pure and seeded molecular beams by femtosecond ion imaging

NARCIS (Netherlands)

Meng, C.; Janssen, M.H.M.

2015-01-01

Here, we report on femtosecond ion imaging experiments to measure the density profile of a pulsed supersonic molecular beam. Ion images are measured for both a molecular beam and bulk gas under identical experimental conditions via femtosecond multiphoton ionization of Xe atoms. We report the

Extraction Compression and Acceleration of High Line Charge Density Ion Beams

CERN Document Server

Henestroza, Enrique; Grote, D P; Peters, Craig; Yu, Simon

2005-01-01

HEDP applications require high line charge density ion beams. An efficient method to obtain this type of beams is to extract a long pulse, high current beam from a gun at high energy, and let the beam pass through a decelerating field to compress it. The low energy beam bunch is loaded into a solenoid and matched to a Brillouin flow. The Brillouin equilibrium is independent of the energy if the relationship between the beam size (a), solenoid magnetic field strength (B) and line charge density is such that (Ba)2

High energy density in matter produced by heavy ion beams. Annual report 1993

International Nuclear Information System (INIS)

1994-06-01

The experimental activities at GSI were concentrated on the progress in beam-plasma interaction experiments of heavy ion with ionized matter, plasma -lens forming devices, intense beam at high temperature experimental area, and charge exchange collisions of ions. The development to higher intensities and phase space densities during 1993 for the SIS and the ESR is recorded. The possibility of studying of funneling of two beams in a two-beam RFQ is studied. Specific results are presented with respect to inertial confinement fusion (ICF). The problem of ion stopping in plasma and pumping X-ray lasers with heavy ion beams are discussed. Various contributions deal with dense plasma effects, shocks and opacity. (HP)

Heavy ions

CERN Multimedia

CERN. Geneva; Antinori, Federico

2001-01-01

Colliding two heavy nuclei at ultrarelativistic energies allows to create in the laboratory a bulk system with huge density, pressure and temperature and to study its properties. It is estimated that in Pb-Pb collisions at CERN-SPS we reach over an appreciable volume an energy density which exceeds by more than a factor 20 that of normal nuclear matter. At such densities, the hadrons are so closely packed that they interpenetrate; novel physics phenomena are expected to appear. QCD predicts that under such conditions a phase transition from a system composed of colourless hadrons to a Quark-Gluon Plasma (QGP) should occur. A rich ultrarelativistic heavy-ion physics programme is under way both at BNL-AGS and at CERN-SPS since 1986. The results obtained so far have led CERN to officially announce evidence for a new state of matter last year. A long-range programme of heavy-ion physics at higher energies is under way (BNL-RHIC) and in preparation (CERN-LHC). These lectures are meant as an introduction to the phy...

Heavy ions

CERN Multimedia

CERN. Geneva. Audiovisual Unit

2002-01-01

Colliding two heavy nuclei at ultrarelativistic energies allows to create in the laboratory a bulk system with huge density, pressure and temperature and to study its properties. It is estimated that in Pb-Pb collisions at CERN-SPS we reach over an appreciable volume an energy density which exceeds by more than a factor 20 that of normal nuclear matter. At such densities, the hadrons are so closely packed that they interpenetrate; novel physics phenomena are expected to appear. QCD predicts that under such conditions a phase transition from a system composed of colourless hadrons to a Quark-Gluon Plasma (QGP) should occur. A rich ultrarelativistic heavy-ion physics programme is under way both at BNL-AGS and at CERN-SPS since 1986. The results obtained so far have led CERN to officially announce evidence for a new state of matter last year. A long-range programme of heavy-ion physics at higher energies is under way (BNL-RHIC) and in preparation (CERN-LHC). These lectures are meant as an introduction to the phy...

Density, potential and temperature fluctuations in Wendelstein 7-AS and ASDEX

Energy Technology Data Exchange (ETDEWEB)

Balbin, R; Hidalgo, C [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain); Carlson, A; Endler, M; Giannone, L.; Niedermeyer, H; Rudyj, A; Theimer, G [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)

1993-12-31

Measurements of density, potential and temperature fluctuations in Wendelstein 7-AS stellarator (W7-AS) and ASDEX tokamak have been carried out. The properties of plasma fluctuations in a tokamak and stellarator can then be compared. A reciprocating Langmuir probe with an array of 19 graphite tips has been used to measure the radial profiles of fluctuations in the ion saturation current and floating potential in W7-AS and ASDEX. In both devices, a reversal in radial electric field and an associated velocity shear layer at the plasma boundary have been observed and in both cases the normalized ion saturation current fluctuation level decreases monotonically moving towards the plasma centre and through the shear layer. At the radial position where the phase velocity in the poloidal direction of the fluctuations goes to zero, the normalized ion saturation current fluctuation level of 0.25 are similar for edge plasma parameters of similar temperatures and densities. A spatial crosscorrelation between fluctuations in floating potential and ion saturation current has been observed in both machines. (author) 6 refs., 4 figs.

A note on asymptotic normality in the thermodynamic limit at low densities

DEFF Research Database (Denmark)

Jensen, J.L.

1991-01-01

We consider a continuous statistical mechanical system with a pair interaction in a region λ tending to infinity. For low densities asymptotic normality of the canonical statistic is proved, both in the grand canonical ensemble and in the canonical ensemble. The results are illustrated through...

Dust ion acoustic solitary waves in a magnetized dusty plasma with anisotropic ion pressure

International Nuclear Information System (INIS)

Choi, Cheong Rim; Ryu, Chang-Mo; Lee, D.-Y.; Lee, Nam C.; Kim, Y.-H.

2007-01-01

The influence of anisotropic ion pressure on the dust ion acoustic solitary wave (DIASW) and the double layer (DL) obliquely propagating to a magnetic field are investigated by using the Sagdeev potential. The anisotropic ion pressure is defined by applying the Chew-Goldberger-Low (CGL) theory, p-perpendicular=p-perpendicular 0 n and p-parallel=p-parallel 0 n 3 , where n is the normalized ion density. The solutions of DIASWs and DLs obliquely propagating to an external magnetic field are obtained in the small amplitude limit. It is found that the perpendicular component of anisotropic ion pressure works differently from that of the parallel component on the DIASWs in a magnetized dusty plasma, deviating from a straight extension of the isotropic pressure effect

Features of the normal choriocapillaris with OCT-angiography: Density estimation and textural properties.

Science.gov (United States)

Montesano, Giovanni; Allegrini, Davide; Colombo, Leonardo; Rossetti, Luca M; Pece, Alfredo

2017-01-01

The main objective of our work is to perform an in depth analysis of the structural features of normal choriocapillaris imaged with OCT Angiography. Specifically, we provide an optimal radius for a circular Region of Interest (ROI) to obtain a stable estimate of the subfoveal choriocapillaris density and characterize its textural properties using Markov Random Fields. On each binarized image of the choriocapillaris OCT Angiography we performed simulated measurements of the subfoveal choriocapillaris densities with circular Regions of Interest (ROIs) of different radii and with small random displacements from the center of the Foveal Avascular Zone (FAZ). We then calculated the variability of the density measure with different ROI radii. We then characterized the textural features of choriocapillaris binary images by estimating the parameters of an Ising model. For each image we calculated the Optimal Radius (OR) as the minimum ROI radius required to obtain a standard deviation in the simulation below 0.01. The density measured with the individual OR was 0.52 ± 0.07 (mean ± STD). Similar density values (0.51 ± 0.07) were obtained using a fixed ROI radius of 450 μm. The Ising model yielded two parameter estimates (β = 0.34 ± 0.03; γ = 0.003 ± 0.012; mean ± STD), characterizing pixel clustering and white pixel density respectively. Using the estimated parameters to synthetize new random textures via simulation we obtained a good reproduction of the original choriocapillaris structural features and density. In conclusion, we developed an extensive characterization of the normal subfoveal choriocapillaris that might be used for flow analysis and applied to the investigation pathological alterations.

Measurement of the radial density distribution of the light emissions near the trajectory of fast ions in nitrogen

International Nuclear Information System (INIS)

Ibach, T.

1983-11-01

For the analysis of the emission and deceleration mechanisms of ionisation-electrons (delta-electrons) during the passage of fast ions through gases, the radial density distribution of the light emission has been measured, which is related with the (0,0)-transitions of two optical bands in nitrogen. These measurements have been made using a small aperture limited ion beam. The first band under study is the 2. positive system at 337.1 nm excited mainly by low energy electrons around 20 eV, and the second band is the 1. negative system at 391.4 nm excited by fast electrons with simultaneous ionisation. For these measurements an experimental setup has been developed with a telescope-like optical system and interference filters to detect the emitted light with a high spacial resolution (4x10 -4 of profile width) and a high dynamic range (10 6 ). The experiments have been performed using proton beams of different energies between 270 keV and 2.8 MeV, He-3 beams with 270 keV/u and 500 keV/u and a Ne beam with 270 keV/u with gas pressures in the range between 0.133 to 13.3 mbar. Based on the method of Abel inversion the spacial light emission density is deduced from the experimental distance functions and normalized to a gas density of 1 g/cm 3 . The results show that approximately half of the total light emission in the 1. negative system and the ionisation is caused by the primary interaction of the ion beam. For the same energy per nucleon this contribution decreases relative to the contribution of the delta-electrons with increasing atomic number. In addition the delta-radiation becomes harder with increasing atomic number. Good agreement is obtained by comparison with the results of other authors, which are based on probe techniques and Monte-Carlo-calculations. (orig./HP) [de

Density of uranium ions in the 4I0/sub 9/2/ ground state in a hollow-cathode type discharge

International Nuclear Information System (INIS)

Pianarosa, P.; Bouchard, P.; Saint-Dizier, J.P.; Gagne, J.M.

1983-01-01

A hollow-cathode type discharge cell as generator of uranium ions is investigated. The 4 I 0 /sub 9/2/ ground-state ion density has been obtained by absorption spectroscopy at 5493 and 4244 A. The absorption measurements have been performed using two identical hollow-cathode lamps: one acting as a light source, the other as a reservoir of free ions. Neon and xenon have been used as discharge sustaining gases. In our experimental conditions the measured ion ground-state density is of the order of 10 12 ions cm -3 . Absorption measurements performed at 5915 and 4246 A of U i give a density of the order of 10 12 atoms cm -3 . This latter value is in excellent agreement with a previously measured value obtained by laser-absorption spectroscopy

High Energy Density Solid State Li-ion Battery with Enhanced Safety, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — We propose to develop an all solid state Li-ion battery which is capable of delivering high energy density, combined with high safety over a wide operating...

Measurement of heat load density profile on acceleration grid in MeV-class negative ion accelerator.

Science.gov (United States)

Hiratsuka, Junichi; Hanada, Masaya; Kojima, Atsushi; Umeda, Naotaka; Kashiwagi, Mieko; Miyamoto, Kenji; Yoshida, Masafumi; Nishikiori, Ryo; Ichikawa, Masahiro; Watanabe, Kazuhiro; Tobari, Hiroyuki

2016-02-01

To understand the physics of the negative ion extraction/acceleration, the heat load density profile on the acceleration grid has been firstly measured in the ITER prototype accelerator where the negative ions are accelerated to 1 MeV with five acceleration stages. In order to clarify the profile, the peripheries around the apertures on the acceleration grid were separated into thermally insulated 34 blocks with thermocouples. The spatial resolution is as low as 3 mm and small enough to measure the tail of the beam profile with a beam diameter of ∼16 mm. It was found that there were two peaks of heat load density around the aperture. These two peaks were also clarified to be caused by the intercepted negative ions and secondary electrons from detailed investigation by changing the beam optics and gas density profile. This is the first experimental result, which is useful to understand the trajectories of these particles.

Measurement of heat load density profile on acceleration grid in MeV-class negative ion accelerator

Energy Technology Data Exchange (ETDEWEB)

Hiratsuka, Junichi, E-mail: hiratsuka.junichi@jaea.go.jp; Hanada, Masaya; Kojima, Atsushi; Umeda, Naotaka; Kashiwagi, Mieko; Yoshida, Masafumi; Nishikiori, Ryo; Ichikawa, Masahiro; Watanabe, Kazuhiro; Tobari, Hiroyuki [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka 311-0193 (Japan); Miyamoto, Kenji [Naruto University of Education, 748 Nakashima, Takashima, Naruto-cho, Naruto-shi, Tokushima 772-8502 (Japan)

2016-02-15

To understand the physics of the negative ion extraction/acceleration, the heat load density profile on the acceleration grid has been firstly measured in the ITER prototype accelerator where the negative ions are accelerated to 1 MeV with five acceleration stages. In order to clarify the profile, the peripheries around the apertures on the acceleration grid were separated into thermally insulated 34 blocks with thermocouples. The spatial resolution is as low as 3 mm and small enough to measure the tail of the beam profile with a beam diameter of ∼16 mm. It was found that there were two peaks of heat load density around the aperture. These two peaks were also clarified to be caused by the intercepted negative ions and secondary electrons from detailed investigation by changing the beam optics and gas density profile. This is the first experimental result, which is useful to understand the trajectories of these particles.

Energy density, stopping and flow in ultrarelativistic heavy ion collisions

International Nuclear Information System (INIS)

Sorge, H.; von Keitz, A.; Mattiello, R.; Stoecker, H.; Greiner, W.

1990-01-01

The Lorentz invariant molecular dynamics approach (RQMD) is employed to investigate the space-time evolution of heavy ion collisions at energies (E kin = 10AGeV hor-ellipsis 200AGeV). The calculations for various nucleus nucleus reactions show a high degree of stopping power. The importance of secondary rescattering at these beam energies is demonstrated. The computed nucleon rapidity distributions are compared to available experimental data. It is demonstrated that nonlinear, collective effects like full stopping of target and projectile and matter flow could be expected for heavy projectiles only. For nuclear collisions in the Booster era at BNL and for the lead beam at CERN SPS the authors predict a stimulating future: then a nearly equilibrated, long lived (8 fm/c) macroscopic volume of very high energy density (> 1 GeV/fm 3 ) and baryon density (> 5 times ground state density) is produced

Fast-ion transport in low density L-mode plasmas at TCV using FIDA spectroscopy and the TRANSP code

DEFF Research Database (Denmark)

Geiger, B.; Karpushov, A.; Duval, B. P.

2017-01-01

Experiments with the new neutral beam injection source of TCV have been performed with high fast-ion fractions (>20%) that exhibit a clear reduction of the loop voltage and a clear increase of the plasma pressure in on- and off-axis heating configurations. However, good quantitative......, a newly installed fast-ion D-alpha (FIDA) spectroscopy system measures strong passive radiation and, hence, indicates the presence of high background neutral densities such that charge-exchange losses are substantial. Also the active radiation measured with the FIDA diagnostic, as well as data from...... a neutral particle analyzer, suggest strong fast-ion losses and large neutral densities. The large neutral densities can be justified since high electron temperatures (3–4 keV), combined with low electron densities (about 2 X 1019 m−3) yield long mean free paths of the neutrals which are penetrating from...

Highly Oriented Graphene Sponge Electrode for Ultra High Energy Density Lithium Ion Hybrid Capacitors.

Science.gov (United States)

Ahn, Wook; Lee, Dong Un; Li, Ge; Feng, Kun; Wang, Xiaolei; Yu, Aiping; Lui, Gregory; Chen, Zhongwei

2016-09-28

Highly oriented rGO sponge (HOG) can be easily synthesized as an effective anode for application in high-capacity lithium ion hybrid capacitors. X-ray diffraction and morphological analyses show that successfully exfoliated rGO sponge on average consists of 4.2 graphene sheets, maintaining its three-dimensional structure with highly oriented morphology even after the thermal reduction procedure. Lithium-ion hybrid capacitors (LIC) are fabricated in this study based on a unique cell configuration which completely eliminates the predoping process of lithium ions. The full-cell LIC consisting of AC/HOG-Li configuration has resulted in remarkably high energy densities of 231.7 and 131.9 Wh kg(-1) obtained at 57 W kg(-1) and 2.8 kW kg(-1). This excellent performance is attributed to the lithium ion diffusivity related to the intercalation reaction of AC/HOG-Li which is 3.6 times higher that of AC/CG-Li. This unique cell design and configuration of LIC presented in this study using HOG as an effective anode is an unprecedented example of performance enhancement and improved energy density of LIC through successful increase in cell operation voltage window.

High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region

Energy Technology Data Exchange (ETDEWEB)

Hirano, Y., E-mail: y.hirano@aist.go.jp, E-mail: hirano.yoichi@phys.cst.nihon-u.ac.jp [Innovative Plasma Processing Group, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); College of Science and Technologies, Nihon University, Chiyodaku, Tokyo 101-0897 (Japan); Kiyama, S.; Koguchi, H. [Innovative Plasma Processing Group, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Fujiwara, Y.; Sakakita, H. [Innovative Plasma Processing Group, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Department of Engineering Mechanics and Energy, University of Tsukuba, Ibaraki 305-8577 (Japan)

2015-11-15

A high current density (≈3 mA/cm{sup 2}) hydrogen ion beam source operating in an extremely low-energy region (E{sub ib} ≈ 150–200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E{sub ib} is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.

Brain parenchymal density measurements by CT in demented subjects and normal controls

International Nuclear Information System (INIS)

Gado, M.; Danziger, W.L.; Chi, D.; Hughes, C.P.; Coben, L.A.

1983-01-01

Parachymal density measurements of 14 regions of gray and white matter from each cerebral hemisphere were made from CT scans of 25 subjects who had varying degrees of dementia as measured by a global Clinical Dementia Rating, and also from CT scans of 33 normal control subjects. There were few significant differences between the two groups in the mean density value for each of the regions examined, although several individual psychometric tests did correlate with density changes. Moreover, for six regions in the cerebral cortex, and for one region in the thalamus of each hemisphere, we found no significant correlation between the gray-white matter density difference and dementia. There was, however, a loss of the discriminability between the gray and white matter with an increase in the size of the ventricles. These findings may be attributed to the loss of white matter volume

Corneal endothelial cell density and morphology in normal Iranian eyes

Directory of Open Access Journals (Sweden)

Fallah Mohammad

2006-03-01

Full Text Available Abstract Background We describe corneal endothelial cell density and morphology in normal Iranian eyes and compare endothelial cell characteristics in the Iranian population with data available in the literature for American and Indian populations. Methods Specular microscopy was performed in 525 eyes of normal Iranian people aged 20 to 85 years old. The studied parameters including mean endothelial cell density (MCD, mean cell area (MCA and coefficient of variation (CV in cell area were analyzed in all of the 525 eyes. Results MCD was 1961 ± 457 cell/mm2 and MCA was 537.0 ± 137.4 μm2. There was no statistically significant difference in MCD, MCA and CV between genders (Student t-test, P = 0.85, P = 0.97 and P = 0.15 respectively. There was a statistically significant decrease in MCD with age (P r = -0.64. The rate of cell loss was 0.6% per year. There was also a statistically significant increase in MCA (P r = 0.56 and CV (P r = 0.30 from 20 to 85 years of age. Conclusion The first normative data for the endothelium of Iranian eyes seems to confirm that there are no differences in MCD, MCA and CV between genders. Nevertheless, the values obtained in Iranian eyes seem to be different to those reported by the literature in Indian and American populations.

Ion transition heights from topside electron density profiles

International Nuclear Information System (INIS)

Titheridge, J.E.

1976-01-01

Theoretical electron density profiles are calculated for the topside ionosphere to determine the major factors controlling the profile shape. Only the mean temperature, the vertical temperature gradient and the O + /H + ion transition height are important. Vertical proton fluxes alter the ion transition height but have no other effect on the profile shape. Diffusive equilibrium profiles including only these three effects fit observed profiles, at all latitudes, to within experimental accuracy. Values of plasma temperature, temperature gradient and ion transition height hsub(T) were determined by fitting theoretical models to 60,000 experimental profiles obtained from Alouette 1 ionograms, at latitudes of 75 0 S to 85 0 N near solar minimum. Inside the plasmasphere hsub(T) varies from about 500 km on winter nights to 850 km on summer days. Diurnal variations are caused primarily by the production and loss of O + in the ionosphere. The approximately constant winter night value of hsub(T) is close to the level for chemical equilibrium. In summer hsub(T) is always above the equilibrium level, giving a continual production of protons which travel along lines of force to aid in maintaining the conjugate winter night ionosphere. Outside the plasmasphere hsub(T) is 300 to 600 km above the equilibrium level at all times. This implies a continual near-limiting upwards flux of protons which persists down to latitudes of about 60 0 at night and 50 0 during the day. (author)

Preliminary scaling laws for plasma current, ion kinetic temperature, and plasma number density in the NASA Lewis bumpy torus plasma

Science.gov (United States)

Roth, J. R.

1976-01-01

Parametric variation of independent variables which may affect the characteristics of bumpy torus plasma have identified those which have a significant effect on the plasma current, ion kinetic temperature, and plasma number density, and those which do not. Empirical power law correlations of the plasma current, and the ion kinetic temperature and number density were obtained as functions of potential applied to the midplane electrode rings, the background neutral gas pressure, and the magnetic field strength. Additional parameters studied included the type of gas, the polarity of the midplane electrode rings, the mode of plasma operation, and the method of measuring the plasma number density. No significant departures from the scaling laws appear to occur at the highest ion kinetic temperatures or number densities obtained to date.

Profiles of plasma parameters and density of negative hydrogen ions by laser detachment measurements in RF-driven ion sources; Profile der Plasmaparameter und Dichte negativer Wasserstoffionen mittels Laserdetachmentmessungen in HF-angeregten Ionenquellen

Energy Technology Data Exchange (ETDEWEB)

Christ-Koch, Sina

2007-12-20

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 ({proportional_to} 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{sup -})=1.10{sup 17} 1/m{sup 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.)

Axial magnetic field extraction type microwave ion source with a permanent magnet

International Nuclear Information System (INIS)

Ishikawa, Junzo; Takagi, Toshinori

1984-01-01

A new type of microwave ion source in which a permanent magnet generates an axially directed magnetic field needed for the electron cyclotron resonance was developed. The electron cyclotron resonance produces a high density plasma in the ion source. A mA-order ion beam can be extracted. Compared with usual microwave ion sources, this source has a distinguished feature in that the axially directed magnetic field is formed by use of a permanent magnet. Shape of magnetic force lines near the ion extraction aperture was carefully investigated. The extracted ion current as a function of the ion extraction voltage was measured. The experimental data are in good agreement with the theoretical line. The ion source can be heated up to 500 deg C, and extraction of the alkaline metal ions is possible. The extracted ion current for various elements are shown in the table. The current density normalized by the proton was 350-650 mA/cm 2 which was nearly equal to the upper limit of the extractable positive ion current density. The plasma density was estimated and was 2 - 3 x 10 12 cm -3 . The mass spectrum of a Cesium ion beam was obtained. A negligible amount of impurities was observed. The emittance diagram of the extracted ion beam was measured. The result shows that a low emittance and high brightness ion source is constructed. (Kato, T.)

Study of electron densities of normal and neoplastic human breast tissues by Compton scattering using synchrotron radiation

Energy Technology Data Exchange (ETDEWEB)

Antoniassi, M.; Conceicao, A.L.C. [Departamento de Fisica-Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto-Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil); Poletti, M.E., E-mail: poletti@ffclrp.usp.br [Departamento de Fisica-Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto-Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil)

2012-07-15

Electron densities of 33 samples of normal (adipose and fibroglangular) and neoplastic (benign and malignant) human breast tissues were determined through Compton scattering data using a monochromatic synchrotron radiation source and an energy dispersive detector. The area of Compton peaks was used to determine the electron densities of the samples. Adipose tissue exhibits the lowest values of electron density whereas malignant tissue the highest. The relationship with their histology was discussed. Comparison with previous results showed differences smaller than 4%. - Highlights: Black-Right-Pointing-Pointer Electron density of normal and neoplastic breast tissues was measured using Compton scattering. Black-Right-Pointing-Pointer Monochromatic synchrotron radiation was used to obtain the Compton scattering data. Black-Right-Pointing-Pointer The area of Compton peaks was used to determine the electron densities of samples. Black-Right-Pointing-Pointer Adipose tissue shows the lowest electron density values whereas the malignant tissue the highest. Black-Right-Pointing-Pointer Comparison with previous results showed differences smaller than 4%.

Study of electron densities of normal and neoplastic human breast tissues by Compton scattering using synchrotron radiation

International Nuclear Information System (INIS)

Antoniassi, M.; Conceição, A.L.C.; Poletti, M.E.

2012-01-01

Electron densities of 33 samples of normal (adipose and fibroglangular) and neoplastic (benign and malignant) human breast tissues were determined through Compton scattering data using a monochromatic synchrotron radiation source and an energy dispersive detector. The area of Compton peaks was used to determine the electron densities of the samples. Adipose tissue exhibits the lowest values of electron density whereas malignant tissue the highest. The relationship with their histology was discussed. Comparison with previous results showed differences smaller than 4%. - Highlights: ► Electron density of normal and neoplastic breast tissues was measured using Compton scattering. ► Monochromatic synchrotron radiation was used to obtain the Compton scattering data. ► The area of Compton peaks was used to determine the electron densities of samples. ► Adipose tissue shows the lowest electron density values whereas the malignant tissue the highest. ► Comparison with previous results showed differences smaller than 4%.

Experiments on the indirect heating of low density aerogels for applications in heavy ion stopping in plasma

International Nuclear Information System (INIS)

Rosmej, O.N.; Blazevic, A.; Suslov, N.; Kunin, A.; Pinegin, A.; Schaefer, D.; Nisius, Th.; Zhao, Y.; Rinecker, T.; Wiechula, J.

2010-01-01

Complete text of publication follows. The unique combination of a Petawatt High-Energy Laser System for Ion beam eXperiments - 'Phelix' (Nd:glass, 1053 nm, 300-500 J, 1-15 ns) and intense heavy ion beams of the UNILAC accelerator at GSI-Darmstadt allow creating and probing of hot plasma with a density of some percentage of solid-state density. The experimental program aims at the investigation of fundamental features of heavy ion stopping in ionized matter in view of promising applications for the Heavy Ion Fusion and astrophysics. For combined experiments on the interaction of heavy ion beams with ionized matter (GSI) a high density plasma target with homogeneous in time (∼ 5 ns) and space (∼ 1 mm) plasma parameters in required. For these purposes we are developing the combined target which consists on the Gold hohlraum (converter) and low Z foam target heated by the hohlraum radiation before probed by an ion bunch. Foam targets are rather promising due to the effective conversion of the deposited radiation energy into the internal plasma energy and slow hydrodynamic response on the heating. Direct irradiation of the Gold converter walls with a nanosecond pulse delivered by the PHELIX-laser system (GSI) leads to hohlraum radiation spectra in the photon energy range of 50-500 eV. Expected temperatures of the foam targets heated by this radiation amount to 20-30 eV at electron densities of 10 21 cm -3 . The results of the last hohlraum experiments carried out at PHELIX-laser energies of 200-250 J will be presented. In experiments the hohlraum radiation field, the conversion efficiency of the laser energy into soft X-rays, duration of the soft X-ray pulse, and parameters of the heated with X-rays foam targets have been measured. Acknowledgements. This work is supported by ISTC 2264 grant.

Electrodeposition of high-density lithium vanadate nanowires for lithium-ion battery

Science.gov (United States)

Hua, Kang; Li, Xiujuan; Fang, Dong; Yi, Jianhong; Bao, Rui; Luo, Zhiping

2018-07-01

Lithium vanadate nanowires have been electrodeposited onto a titanium (Ti) foil by a direct current electrodeposition without template. The morphology, crystal structure, and the effects of deposition voltage, temperature and time on the prepared samples were tested and presented. The as-prepared lithium vanadate nanowires/Ti composite can be used as electrode for lithium-ion battery. Electrochemical measurements showed that the electrode displayed a specific discharge capacitance as high as 235.1 mAh g-1 after 100 cycles at a current density of 30 mA g-1. This research provides a new pathway to explore high tap density vanadates nanowires on metals with enhanced electrochemical performance.

Analytic theory of the Rayleigh-Taylor instability in a uniform density plasma-filled ion diode

International Nuclear Information System (INIS)

Hussey, T.W.; Payne, S.S.

1987-04-01

The J-vector x B-vector forces associated with the surface current of a plasma-filled ion diode will accelerate this plasma fill toward the anode surface. It is well known that such a configuration with a high I is susceptible to the hydromagnetic Rayleigh-Taylor instability in certain geometries. A number of ion diode plasma sources have been proposed, most of which have a falling density going away from the wall. A somewhat more unstable case, however, is that of uniform density. In this report we attempt to establish an upper limit on this effect with a simple analytic model in which a uniform-density plasma is accelerated by the magnetic field anticipated in a PBFA-II diode. We estimate the number of linear e-foldings experienced by an unstable surface as well as the most damaging wavelength initial perturbation. This model, which accounts approximately for stabilization due to field diffusion, suggests that even with a uniform fill, densities in excess of a few 10 15 are probably not damaged by the instability. In addition, even lower densities might be tolerated if perturbations near the most damaging wavelength can be kept very small

Fabrication and demonstration of high energy density lithium ion microbatteries

Science.gov (United States)

Sun, Ke

density on a limited footprint area. In chapter 4, Li-ion batteries based on the LiMn2O4-TiP 2O7 couple are manufactured on flexible paper substrates; where the use of light-weight paper substrates significantly increase the gravimetric energy density of this electrode couple as compared to traditional metal current collectors. In chapter 5, a novel nanowire growth mechanism will be explored to grow interdigitated metal oxide nanowire micro battery electrodes. The growth kinetics of this mechanism is systematically studied to understand how to optimize the growth process to produce electrodes with improved electrochemical properties.

Event-by-event gluon multiplicity, energy density, and eccentricities in ultrarelativistic heavy-ion collisions

Science.gov (United States)

Schenke, Björn; Tribedy, Prithwish; Venugopalan, Raju

2012-09-01

The event-by-event multiplicity distribution, the energy densities and energy density weighted eccentricity moments ɛn (up to n=6) at early times in heavy-ion collisions at both the BNL Relativistic Heavy Ion Collider (RHIC) (s=200GeV) and the CERN Large Hardron Collider (LHC) (s=2.76TeV) are computed in the IP-Glasma model. This framework combines the impact parameter dependent saturation model (IP-Sat) for nucleon parton distributions (constrained by HERA deeply inelastic scattering data) with an event-by-event classical Yang-Mills description of early-time gluon fields in heavy-ion collisions. The model produces multiplicity distributions that are convolutions of negative binomial distributions without further assumptions or parameters. In the limit of large dense systems, the n-particle gluon distribution predicted by the Glasma-flux tube model is demonstrated to be nonperturbatively robust. In the general case, the effect of additional geometrical fluctuations is quantified. The eccentricity moments are compared to the MC-KLN model; a noteworthy feature is that fluctuation dominated odd moments are consistently larger than in the MC-KLN model.

Nanopore density effect of polyacrylamide gel plug on electrokinetic ion enrichment in a micro-nanofluidic chip

Science.gov (United States)

Wang, Jun-yao; Xu, Zheng; Li, Yong-kui; Liu, Chong; Liu, Jun-shan; Chen, Li; Du, Li-qun; Wang, Li-ding

2013-07-01

In this paper, the nanopore density effect on ion enrichment is quantitatively described with the ratio between electrophoresis flux and electroosmotic flow flux based on the Poisson-Nernst-Planck equations. A polyacrylamide gel plug is integrated into a microchannel to form a micro-nanofluidic chip. With the chip, electrokinetic ion enrichment is relatively stable and enrichment ratio of fluorescein isothiocyanate can increase to 600-fold within 120 s at the electric voltage of 300 V. Both theoretical research and experiments show that enrichment ratio can be improved through increasing nanopore density. The result will be beneficial to the design of micro-nanofluidic chips.

Ionization of liquid argon by x-rays: effect of density on electron thermalization and free ion yields

International Nuclear Information System (INIS)

Huang, S.S.-S.; Gee, N.; Freeman, G.R.

1991-01-01

Free ion yields were measured in liquid argon as a function of electric field strength at densities 736-1343 kg/m 3 (temperatures 149-95 K). The field dependence of the yields was parametrized using the extended Onsager and box models. Over the present density range the total ion yield was constant within 1% and was taken as 4.4, the average of earlier values at 87-91 K. The absence of internal vibrational modes in argon makes its electron thermalizing ability smaller than that of methane. The electron thermalization distance b GP in liquid argon is 3-5 times longer than that in liquid methane at a given d/d c (d c = critical fluid density). (author)

Studies on the production of high energy densities in matter by intense heavy-ion beams

International Nuclear Information System (INIS)

Jacoby, J.

1989-08-01

In the framework of the present thesis the interaction of an intense heavy-ion beam with a small, but macroscopical amount of matter is studied. Thereby high energy densities in the target matter are produced. For this experiment it was for the first time possible to heat matter with ion beams from conventional heavy-ion accelerators up to plasma conditions. A KR + -ion beam was first accelerated with the heavy-ion accelerator MAXILAC to 45 keV/u and then focussed by a fine-focusing lens to a closed xenon gas target. The light emitted from the target was space- and time resolved taken up by a spectrometer as well as by a streak and CCD camera. Thereby the radial development of the plasma and the penetration behaviour of the ion beam was observed. The free electron density of the plasma was determined from the Stark broadening of emission lines (n e ≅ 4x10 16 cm -3 ). The temperature could be determined by different methods (shock-wave velocity, degree of ionization, line ratios). The electron temperature amounted in the center of the pipe to kT ≅ 0.75 eV. For the opacity of the target by which the emitted light power is determined under the assumption of the two-dimensional model (equilibrium between emitted and absorbed energy) the value κ p ≅ 7700 cm 2 /g resulted. (orig./HSI) [de

Two-dimensional electrodynamic structure of the normal glow discharge in an axial magnetic field

Energy Technology Data Exchange (ETDEWEB)

Surzhikov, S. T., E-mail: surg@ipmnet.ru [Russian Academy of Sciences, Institute for Problems in Mechanics (Russian Federation)

2017-03-15

Results are presented from numerical simulations of an axisymmetric normal glow discharge in molecular hydrogen and molecular nitrogen in an axial magnetic field. The charged particle densities and averaged azimuthal rotation velocities of electrons and ions are studied as functions of the gas pressure in the range of 1–5 Torr, electric field strength in the range of 100–600 V/cm, and magnetic field in the range of 0.01–0.3 T. It is found that the axial magnetic field does not disturb the normal current density law.

Probing neutral density at the plasma edge of Tore Supra with CX excited impurity ions

International Nuclear Information System (INIS)

Hess, W.R.; Mattioli, M.; Guirlet, R.

1993-01-01

In Tokamak plasma physics renewed interest in visible spectroscopy has grown for two reasons. The use of fiber optics allows observation of local sources of both impurities and of hydrogen by observing radiation of low ionization states. Moreover, charge exchange spectroscopy (CXS) with either auxiliary or heating neutral beams is a standard technique to determine the ion temperature and impurity density profiles. After a short description of the experimental setup and the ergodic divertor of Tore Supra (TS), two discharges in which space-resolved observations of the CVI (8-7) line clearly show the presence of CX-related effects. A well isolated spectral line at 5304.6 A is discussed. Tentative identification as CIII (1s 2 2s, 7-5) is suggested. The conclusion shows the usefulness of the reported results for probing neutral density at the plasma edge by detecting CX excited impurity ions and that highly ionized C 6+ ions exist in the MARFE regions. To the best of our knowledge, only very low ionization C and O ions (such as CIII or OIV) have been previously reported in these regions

Analytical evaluation for the sputtering yield of monoatomic solids at normal ion incidence

International Nuclear Information System (INIS)

Shao Qiyun; Pan Zhengying

1994-01-01

A universal formula of sputtering yield for normal incidence of mono-energetic ions on single element targets is presented. The results based on this method are compared with the Monte Carlo simulation and the experimental data. By means of Wilcoxon two-sample paired signed rank test, the statistically significant difference of the above results is discussed

Reflection and absorption of ion-acoustic waves in a plasma density gradient

International Nuclear Information System (INIS)

Ishihara, O.

1977-01-01

Plasma is characterized by electrical quasineutrality and the collective behavior. There exists a longitudinal low-frequency wave called an ion-acoustic wave in a plasma. One problem in the experimental study of ion-acoustic waves has been that sometimes they are observed to be reflected from discharge tube walls, and sometimes to be absorbed. Theoretical computation reveals that a velocity gradient produced by a density gradient plays a significant role in the reflection. The velocity gradient produces the subsonic-supersonic transition and long wavelength waves are reflected before reaching the transition while short wavelength waves penetrate over the transition and are absorbed in the supersonic flow plasma

Predicted precision of ion temperature and impurity fractional density measurements using the JET collective scattering diagnostic

International Nuclear Information System (INIS)

Orsitto, F.

1992-11-01

In a previous investigation the possibility of measuring the bulk ion temperature was considered in detail, in the context of the proposed Thomson scattering diagnostic for fast ions and alpha particles in the Joint European Torus project. In this report we give an affirmative answer to the question of whether good precision can be obtained in the simultaneous determination of the temperatures and densities of plasma ions from a collective scattering experiment provided some conditions are satisfied. (Author)

Hg+ ion density in low-pressure Ar-Hg discharge plasma used for liquid crystal display back-lighting

International Nuclear Information System (INIS)

Goto, Miki; Arai, Toshihiko

1995-01-01

The positive column of a low-pressure Ar-Hg discharge has been applied as a fluorescent light source for illumination. Many studies on the diagnostics and fundamental mechanisms have been carried out on both the classical fluorescent lamp (d=36 mm) and the compact fluorescent lamp (d=12 mm). On the other hand, a lamp of extremely narrow diameter (usually below 6 mm) has been recently developed for liquid crystal display (LCD) back-lighting and its importance is undoubtedly increasing. Some characteristics or mechanisms of the narrow-diameter lamp may be similar to those of the 36 mm one; however the similarity rule does not hold between them due to the contributions from a stepwise ionization process. Therefore, in order to clarify the excitation mechanism in the narrow-diameter lamp quantitatively, various parameters must be measured directly and some analysis must be done. The Hg + ion density and electron density are important parameters for the purpose of clarifying the excitation mechanism quantitatively. In this work, we have measured the Hg + ion density using the modified absorption method, and the electron density using the probe method in the Ar-Hg discharge of the 4 mm bore tube on bath temperature. Moreover, with combining the modified absorption method and the probe method, the Hg 2 + molecular ion density has been determined

Negative Halogen Ions for Fusion Applications

International Nuclear Information System (INIS)

Grisham, L.R.; Kwan, J.W.; Hahto, S.K.; Hahto, S.T.; Leung, K.N.; Westenskow, G.

2006-01-01

Over the past quarter century, advances in hydrogen negative ion sources have extended the usable range of hydrogen isotope neutral beams to energies suitable for large magnetically confined fusion devices. Recently, drawing upon this experience, negative halogen ions have been proposed as an alternative to positive ions for heavy ion fusion drivers in inertial confinement fusion, because electron accumulation would be prevented in negative ion beams, and if desired, the beams could be photo-detached to neutrals. This paper reports the results of an experiment comparing the current density and beam emittance of Cl+ and Cl- extracted from substantially ion-ion plasmas with that of Ar+ extracted from an ordinary electron-ion plasma, all using the same source, extractor, and emittance scanner. At similar discharge conditions, the Cl- current was typically 85-90% of the positive chlorine current, with an e-/ Cl- ratio as low as seven without grid magnets. The Cl- was as much as 76% of the Ar+ current from a discharge with the same RF drive. The minimum normalized beam emittance and inferred ion temperatures of Cl+, Cl-, and Ar+ were all similar, so the current density and optical quality of Cl- appear as suitable for heavy ion fusion driver applications as a positive noble gas ion of similar mass. Since F, I, and Br should all behave similarly in an ion source, they should also be suitable as driver beams

Differences in bone mineral density between normal-weight children and children with overweight and obesity: a systematic review and meta-analysis.

Science.gov (United States)

van Leeuwen, J; Koes, B W; Paulis, W D; van Middelkoop, M

2017-05-01

This study examines the differences in bone mineral density between normal-weight children and children with overweight or obesity. A systematic review and meta-analysis of observational studies (published up to 22 June 2016) on the differences in bone mineral density between normal-weight children and overweight and obese children was performed. Results were pooled when possible and mean differences (MDs) were calculated between normal-weight and overweight and normal-weight and obese children for bone content and density measures at different body sites. Twenty-seven studies, with a total of 5,958 children, were included. There was moderate and high quality of evidence that overweight (MD 213 g; 95% confidence interval [CI] 166, 261) and obese children (MD 329 g; 95%CI [229, 430]) have a significantly higher whole body bone mineral content than normal-weight children. Similar results were found for whole body bone mineral density. Sensitivity analysis showed that the association was stronger in girls. Overweight and obese children have a significantly higher bone mineral density compared with normal-weight children. Because there was only one study included with a longitudinal design, the long-term impact of childhood overweight and obesity on bone health at adulthood is not clear. © 2017 World Obesity Federation.

Achieving High-Energy-High-Power Density in a Flexible Quasi-Solid-State Sodium Ion Capacitor.

Science.gov (United States)

Li, Hongsen; Peng, Lele; Zhu, Yue; Zhang, Xiaogang; Yu, Guihua

2016-09-14

Simultaneous integration of high-energy output with high-power delivery is a major challenge for electrochemical energy storage systems, limiting dual fine attributes on a device. We introduce a quasi-solid-state sodium ion capacitor (NIC) based on a battery type urchin-like Na2Ti3O7 anode and a capacitor type peanut shell derived carbon cathode, using a sodium ion conducting gel polymer as electrolyte, achieving high-energy-high-power characteristics in solid state. Energy densities can reach 111.2 Wh kg(-1) at power density of 800 W kg(-1), and 33.2 Wh kg(-1) at power density of 11200 W kg(-1), which are among the best reported state-of-the-art NICs. The designed device also exhibits long-term cycling stability over 3000 cycles with capacity retention ∼86%. Furthermore, we demonstrate the assembly of a highly flexible quasi-solid-state NIC and it shows no obvious capacity loss under different bending conditions.

On ion injection at quasiparallel shocks

International Nuclear Information System (INIS)

Scholer, M.; Kucharek, H.; Kato, C.

2002-01-01

A large number of numerical experiments has been performed in order to study the interaction of interstellar pickup protons and helium ions with quasiparallel collisionless shocks. The shocks are modeled by a one-dimensional hybrid simulation method which treats the ions as macroparticles and the electrons as a massless fluid. Solar wind alpha particles and pickup protons are included self-consistently. In addition, the particle splitting method is used for the solar wind ions so that the distribution function can be followed over more than 10 orders of magnitude. A large part of the pickup ion distribution is reflected; the reflection efficiency is very high, and can reach in cases where the pickup ion density is low as much as 50%-60%. The reflection efficiency is almost independent of magnetic field-shock normal angle. This indicates that magnetic mirroring is unimportant and does not lead to larger reflection efficiencies. The reflection efficiency of pickup protons rapidly decreases when the pickup ion density exceeds a few percent of the solar wind density. An addition of 25% pickup protons decreases the reflection coefficient for these ions to ∼10%. This represents the fact that a quasiparallel shock cannot be considered as being uncoupled from the upstream region: at high additions of pickup ions the shock structure is changed in such a way as to reflect less pickup ions. The intensity of diffuse ions upstream of a quasiparallel shock does not depend on the temperature of the core distribution. Within the framework of the present model even solar wind distributions with a hard power law tail do not produce higher intensities of diffuse ions. It is argued that this can be understood by the fact that the intrinsic self-consistency between the processes in the upstream region and at the shock transition determines the injection and reflection properties of the core solar wind distribution

Continuum modeling of ion-beam eroded surfaces under normal incidence: Impact of stochastic fluctuations

International Nuclear Information System (INIS)

Dreimann, Karsten; Linz, Stefan J.

2010-01-01

Graphical abstract: Deterministic surface pattern (left) and its stochastic counterpart (right) arising in a stochastic damped Kuramoto-Sivashinsky equation that serves as a model equation for ion-beam eroded surfaces and is systematically investigated. - Abstract: Using a recently proposed field equation for the surface evolution of ion-beam eroded semiconductor target materials under normal incidence, we systematically explore the impact of additive stochastic fluctuations that are permanently present during the erosion process. Specifically, we investigate the dependence of the surface roughness, the underlying pattern forming properties and the bifurcation behavior on the strength of the fluctuations.

High energy density in matter produced by heavy ion beams. Annual report 1987

International Nuclear Information System (INIS)

1988-08-01

Research activities presented in this annual report were carried out in 1987 in the framework of the government-funded program 'High Energy Density in Matter Produced by Heavy Ion Beams'. It addresses fundamental problems of the generation and investigation of hot dense matter. Its initial motivation and its ultimate goal is the question whether inertial confinement can be achieved by intense heavy ion beams. The new accelerator facility SIS/ESR now under construction at GSI will provide an excellent potential for research in this field. The construction work at the new validity is on schedule. The building construction is near completion and the SIS accelerator will have its first beam at the beginning of next year. First experiments at lower intensity will start in summer 1989 and the full program will run after the cooler and storage ring ESR has got operational. Accordingly, the planning and the preparation of the high energy density experiments at this unique facility was an essential part of the activities last year. In this funding period emphasis was given to the experimental activities at the existing accelerator. In addition to a number of accelerator-oriented and instrumental developments, an experiment on beam-plasma interaction had first exciting results, a significant increase of the stopping power for heavy ions in plasma was measured. Other important activities were the investigation of dielectronic recombination of highly charged ions, spectroscopic investigations aiming at the pumping of short wavelength lasers by heavy ion beams and a crossed beam experiment for the determination of Bi + + Bi + ionization cross sections. As in previous years theoretical work an space-charge dominated beam dynamics as well as on hydrodynamics of dense plasmas, radiation transport and beam plasma interaction was continued, thus providing a basis for the future experiments. (orig.)

Regions of low density in the contrast-enhanced pituitary gland: normal and pathologic processes

International Nuclear Information System (INIS)

Chambers, E.F.; Turski, P.A.; LaMasters, D.; Newton, T.H.

1982-01-01

The incidence of low-density regions in the contrast-enhanced pituitary gland and the possible causes of these regions were investigated by a retrospective review of computed tomographic (CT) scans of the head in 50 patients and autopsy specimens of the pituitary in 100 other patients. It was found that focal areas of low density within the contrast enhanced pituitary gland can be caused by various normal and pathologic conditions such as pituitary microadenomas, pars intermedia cysts, foci of metastasis, infarcts, epidermoid cysts, and abscesses. Although most focal low-density regions probably represent pituitary microadenomas, careful clinical correlation is needed to establish a diagnosis

Partial differential equation for the idempotent Dirac density matrix characterized solely by the exact non-relativistic ground-state electron density for spherical atomic ions

International Nuclear Information System (INIS)

March, N.H.

2009-08-01

In this Journal, March and Suhai have earlier set up a first-order Dirac idempotent density matrix theory for one- and two-level occupancy in which the only input required is the nonrelativistic ground-state electron density. Here, an analytic generalization is provided for the case of spherical electron densities for arbitrary level occupancy. Be-like atomic ions are referred to as an example, but 'almost spherical' molecules like SiH 4 and GeH 4 also become accessible. (author)

Role of ion magnetization in formation of radial density profile in magnetically expanding plasma produced by helicon antenna

Science.gov (United States)

Yadav, Sonu; Ghosh, Soumen; Bose, Sayak; Barada, Kshitish K.; Pal, Rabindranath; Chattopadhyay, Prabal K.

2018-04-01

Experimentally, the density profile in the magnetic nozzle of a helicon antenna based plasma device is seen to be modified from being centrally peaked to that of hollow nature as the external magnetic field is increased. It occurs above a characteristic field value when the ions become magnetized in the expansion chamber. The density profile in the source chamber behind the nozzle, however, remains peaked on-axis irrespective of the magnetic field. The electron temperature there is observed to be hollow and this nature is carried to the expansion chamber along the field line. In the electron energy distribution near the off axis peak location, a high energy tail exists. Rotation of these tail electrons in the azimuthal direction due to the gradient-B drift in the expansion chamber leads to an additional off-axis ionization and forms the hollow density profile. It seems that if the ions are not magnetized, then the off-axially produced additional plasma is not confined and the density profile retains the on-axis peak nature. The present experiment successfully demonstrates how the knowledge of the ion magnetization together with tail electrons significantly contributes to the design of an efficient helicon plasma based thruster.

Development of D-region electron and ion densities under various auroral conditions during the Energy Budget Campaign (EBC)

International Nuclear Information System (INIS)

Brekke, A.; Holt, O.; Friedrich, M.; Hansen, T.; Stauning, P.; Thrane, E.V.

1985-01-01

D-region electron density profiles and time variations were obtained during the Energy Budget Campaign 1980 by a partial reflection radar at Ramfjordmoen, Tromso, located between the rocket ranges at Andoya and Kiruna. The observations were made under various geophysical conditions which are illustrated by riometer observations. The partial reflection measurements indicate that the rockets were launched into a relatively stable D-region on two occasions, while it was somewhat more disturbed on the third. A comparison between the electron density profiles derived by the partial reflection technique and rocket borne probes and Faraday rotation experiments does indicate fair agreement during the quiet conditions, but relatively large discrepancies during disturbed conditions. Simultaneously derived electron density profiles, by use of the Faraday technique, and ion density profiles, by gridded electrostatic spheres mounted on the rocket payload, have made it possible to estimate the negative ion to electron density ratio lambda versus height. These values of lambda are within the range of model calculations. (author)

High energy density in matter produced by heavy ion beams

International Nuclear Information System (INIS)

1989-07-01

This Annual Report summarizes research activities carried out in 1988 in the framework of the government-funded program 'High Energy Density in Matter produced by Heavy Ion Beams'. It addresses fundamental problems of the generation of heavy ion beams and the investigation of hot dense plasmas produced by these beams. Its initial motivation and its long-term goal is the feasibility of inertial confinement fusion by intense heavy ion beams. Two outstanding events deserve to be mentioned explicity, the Heavy Ion Inertial Fusion Conference held in Darmstadt and organized by GSI end of June and the first heavy ion beam injected into the new SIS facility in November. The former event attracted more than hundred scientists for three days to the 4th Conference in this field. This symposium showed the impressive progress since the last conference in Washington two years ago. In particular the first beams in MBE-4 at LBL and results of beam plasma interaction experiments at GSI open new directions for future investigations. The ideas for non-Lionvillean injection into storage rings presented by Carlo Rubbia will bring the discussion of driver scenarios into a new stage. The latter event is a milestone for both machine and target experiments. It characterizes the beginning of the commissioning phase for the new SIS/ESR facility which will be ready for experiments at the end of this year. The commissioning of SIS is on schedule and first experiments can start at the beginning of 1990. A status report of the accelerator project is included. Theoretical activities were continued as in previous years, many of them providing guide lines for future experiments, in particular for the radiation transport aspects and for beam-plasma interaction. (orig.)

Monte Carlo neutral density calculations for ELMO Bumpy Torus

International Nuclear Information System (INIS)

Davis, W.A.; Colchin, R.J.

1986-11-01

The steady-state nature of the ELMO Bumpy Torus (EBT) plasma implies that the neutral density at any point inside the plasma volume will determine the local particle confinement time. This paper describes a Monte Carlo calculation of three-dimensional atomic and molecular neutral density profiles in EBT. The calculation has been done using various models for neutral source points, for launching schemes, for plasma profiles, and for plasma densities and temperatures. Calculated results are compared with experimental observations - principally spectroscopic measurements - both for guidance in normalization and for overall consistency checks. Implications of the predicted neutral profiles for the fast-ion-decay measurement of neutral densities are also addressed

Communication: Density functional theory model for multi-reference systems based on the exact-exchange hole normalization.

Science.gov (United States)

Laqua, Henryk; Kussmann, Jörg; Ochsenfeld, Christian

2018-03-28

The correct description of multi-reference electronic ground states within Kohn-Sham density functional theory (DFT) requires an ensemble-state representation, employing fractionally occupied orbitals. However, the use of fractional orbital occupation leads to non-normalized exact-exchange holes, resulting in large fractional-spin errors for conventional approximative density functionals. In this communication, we present a simple approach to directly include the exact-exchange-hole normalization into DFT. Compared to conventional functionals, our model strongly improves the description for multi-reference systems, while preserving the accuracy in the single-reference case. We analyze the performance of our proposed method at the example of spin-averaged atoms and spin-restricted bond dissociation energy surfaces.

Communication: Density functional theory model for multi-reference systems based on the exact-exchange hole normalization

Science.gov (United States)

Laqua, Henryk; Kussmann, Jörg; Ochsenfeld, Christian

2018-03-01

The correct description of multi-reference electronic ground states within Kohn-Sham density functional theory (DFT) requires an ensemble-state representation, employing fractionally occupied orbitals. However, the use of fractional orbital occupation leads to non-normalized exact-exchange holes, resulting in large fractional-spin errors for conventional approximative density functionals. In this communication, we present a simple approach to directly include the exact-exchange-hole normalization into DFT. Compared to conventional functionals, our model strongly improves the description for multi-reference systems, while preserving the accuracy in the single-reference case. We analyze the performance of our proposed method at the example of spin-averaged atoms and spin-restricted bond dissociation energy surfaces.

Heavy ion and proton-induced single event multiple upset

International Nuclear Information System (INIS)

Reed, R.A.; Carts, M.A.; Marshall, P.W.

1997-01-01

Individual ionizing heavy ion events are shown to cause two or more adjacent memory cells to change logic states in a high density CMOS SRAM. A majority of the upsets produced by normally incident heavy ions are due to single-particle events that causes a single cell to upset. However, for grazing angles a majority of the upsets produced by heavy-ion irradiation are due to single-particle events that cause two or more cells to change logic states. Experimental evidence of a single proton-induced spallation reaction that causes two adjacent memory cells to change logic states is presented. Results from a dual volume Monte-Carlo simulation code for proton-induced single-event multiple upsets are within a factor of three of experimental data for protons at normal incidence and 70 degrees

Line profiles of hydrogenic ions from high-temperature and high-density plasmas

International Nuclear Information System (INIS)

Hou Qing; Li Jianming

1991-01-01

Applying the Hooper's first-order theory, the authors calculate the static micro-electric field distributions in plasmas containing various multiply-charged ions. The influences of the impurity concentrations on the micro electric field distributions and on the Lyman profiles (n→1) from hydrogenic ions are analysed. Based on the optical-thin line profiles, the radiation transfer equation in sphere plasmas with various optical depths is solved. The results confirm that the opacity-broadening of the line profiles has almost no effect on the separation of Lyman β splitted peaks. Such separation is determined by electric field at which the static micro-electric field distribution has a maximum. The separation can be utilized for spatially resolved and temporally resolved density diagnostic of fusion plasmas

Densities and temperatures at fragment formation in heavy-ion collision

Energy Technology Data Exchange (ETDEWEB)

Ohnishi, Akira [Hokkaido Univ., Sapporo (Japan)

1998-07-01

In order to clarify whether the liquid-gas phase transition is relevant to the multi-fragment formation found in intermediate energy heavy-ion collisions, we estimate the densities and temperatures at fragment formation in Au+Au collisions at incident energies of 150 MeV/A and 400 MeV/A within the Quantum Molecular Dynamics (QMD) model with and without quantum fluctuations implemented according to the Quantal Langevin (QL) model. The calculated results show that the IMFs are mainly produced inside the unstable region of nuclear matter, which supports the idea of the fragment formation from supercooled nuclear matter. (author)

Evolution of porous network in GaSb under normally incident 60 keV Ar{sup +}-ion irradiation

Energy Technology Data Exchange (ETDEWEB)

Datta, D.P. [SUNAG Laboratory, Institute of Physics, Bhubaneswar 751 005, Odisha (India); Kanjilal, A. [Department of Physics, Shiv Nadar University, Gautam Budh Nagar 203 207, Uttar Pradesh (India); Garg, S.K. [SUNAG Laboratory, Institute of Physics, Bhubaneswar 751 005, Odisha (India); Sahoo, P.K. [School of Physical Sciences, National Institute of Science Education and Research, Bhubaneswar 751 005, Odisha (India); Satpati, B. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Kanjilal, D. [Inter-University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Som, T., E-mail: tsom@iopb.res.in [SUNAG Laboratory, Institute of Physics, Bhubaneswar 751 005, Odisha (India)

2014-08-15

Highlights: • We show the evolution of a nanoporous layer in GaSb under Ar{sup +}-ion bombardment at normal incidence in the hitherto unexplored high fluence regime, namely 7 × 10{sup 16}–3 × 10{sup 18} ions cm{sup −2}. • Fluence dependent formation and growth of patches on top of the nanoporous layer is demonstrated by scanning electron microscopy. • We also show high amount of oxidation of such ion-beam-generated nanoporous structures, with formation of Ga{sub 2}O{sub 3} and Sb{sub 2}O{sub 3}. • Our study reveals the presence of nanocrystallites within the porous layer even at the highest fluence used in the experiment. • We interpret the experimental observations through a qualitative model where we take into account the effect of re-deposition of atoms sputtered from the nanoporous layer during Ar{sup +}-ion irradiation of GaSb. - Abstract: GaSb(1 0 0) samples were irradiated with 60 keV Ar{sup +}-ions at normal incidence for fluences in the range of 7 × 10{sup 16} to 3 × 10{sup 18} ions cm{sup −2} at room temperature, showing gradual evolution of a porous surface layer containing interconnected nanofibers. In particular, fluence dependent formation of patches on the nanoporous layer is observed by scanning electron microscopy. Combined results of grazing incidence x-ray diffraction and transmission electron microscopy reveal the presence of nanocrystallites in the porous structures. Compositional analysis by x-ray photoelectron spectroscopy indicates the development of oxide phases, mainly Ga{sub 2}O{sub 3} and Sb{sub 2}O{sub 3} where the former increases with fluence. We have proposed a model addressing a competition between ion-induced-defect driven growth of the nanoporous layer and redeposition of sputtered target atoms on the growing layer.

Evolution of Field-Aligned Electron and Ion Densities From Whistler Mode Radio Soundings During Quiet to Moderately Active Period and Comparisons With SAMI2 Simulations

Science.gov (United States)

Reddy, A.; Sonwalkar, V. S.; Huba, J. D.

2018-02-01

Knowledge of field-aligned electron and ion distributions is necessary for understanding the physical processes causing variations in field-aligned electron and ion densities. Using whistler mode sounding by Radio Plasma Imager/Imager for Magnetopause-to-Aurora Global Exploration (RPI/IMAGE), we determined the evolution of dayside electron and ion densities along L ˜ 2 and L ˜ 3 (90-4,000 km) during a 7 day (21-27 November 2005) geomagnetically quiet to moderately active period. Over this period the O+/H+ transition height was ˜880 ± 60 km and ˜1000 ± 100 km, respectively, at L ˜ 2 and L ˜ 3. The electron density varied in a complex manner; it was different at L ˜ 2 and L ˜ 3 and below and above the O+/H+ transition height. The measured electron and ion densities are consistent with those from Challenging Minisatellite Payload (CHAMP) and Defense Meteorological Satellite Program (DMSP) and other past measurements, but they deviated from bottomside sounding and International Reference Ionosphere (IRI) 2012 empirical model results. Using SAMI2 (Naval Research Laboratory (NRL) ionosphere model) with reasonably adjusted values of inputs (neutral densities, winds, electric fields, and photoelectron heating), we simulated the evolution of O+/H+ transition height and field-aligned electron and ion densities so that a fair agreement was obtained between the simulation results and observations. Simulation studies indicated that reduced neutral densities (H and/or O) with time limited O+-H charge exchange process. This reduction in neutral densities combined with changes in neutral winds and plasma temperature led to the observed variations in the electron and ion densities. The observation/simulation method presented here can be extended to investigate the role of neutral densities and composition, disturbed winds, and prompt penetration electric fields in the storm time ionosphere/plasmasphere dynamics.

Influence of plasma density and plasma sheath dynamics on the ion implantation by plasma immersion technique

OpenAIRE

Ensinger, Wolfgang

1996-01-01

Influence of plasma density and plasma sheath dynamics on the ion implantation by plasma immersion technique / B. Rauschenbach ... - In: Nuclear instruments and methods in physics research. B. 113. 1996. S. 266-269

Measurements of Ion Stopping around the Bragg Peak in High-Energy-Density Plasmas

Science.gov (United States)

Frenje, Johan

2015-11-01

Over the last few decades, ion stopping in weakly- to strongly-coupled High-Energy-Density (HED) plasmas has been subject to extensive analytical and numerical studies, but only a limited set of experimental data exists to check the validity of these theories. Most of these experiments also did not probe the detailed characteristics of the Bragg peak (peak ion stopping) where the ion velocity is similar to the average thermal electron velocity. To the best of our knowledge, only one exploratory attempt to do this was conducted by Hicks et al., who were able to describe qualitatively the behavior of the Bragg peak for one plasma condition. The work described in this presentation makes significant advances over previous experimental efforts by quantitatively assessing the characteristics of the ion stopping, ranging from low-velocity stopping, through the Bragg peak, to high-velocity stopping for different HED plasma conditions. This was achieved by measuring the energy loss of DD-tritons, D3He-alphas, DD-protons and D3He-protons, with distinctly different velocities, and the results indicate that the stopping power varies strongly with Te and ne. This effort represents the first experimental test of state-of-art plasma-stopping-power theories around the Bragg peak, which is an important first step in our efforts of getting a fundamental understanding of DT-alpha stopping in HED plasmas, a prerequisite for understanding ignition margins in various implosion designs with varying hot spot areal density at the National Ignition Facility. The work described here was performed in part at the LLE National Laser User's Facility (NLUF), and was supported in part by US DOE (Grant No. DE-FG03- 03SF22691), LLNL (subcontract Grant No. B504974) and LLE (subcontract Grant No. 412160-001G).

Calculating the Maximum Density of the Surface Packing of Ions in Ionic Liquids

Science.gov (United States)

Kislenko, S. A.; Moroz, Yu. O.; Karu, K.; Ivaništšev, V. B.; Fedorov, M. V.

2018-05-01

The maximum density of monolayer packing on a graphene surface is calculated by means of molecular dynamics (MD) for ions of characteristic size and symmetry: 1-butyl-3-methylimidazolium [BMIM]+, tetrabutylammonium [TBA]+, tetrafluoroborate [BF4]-, dicyanamide [DCA]-, and bis(trifluoromethane) sulfonimide [TFSI]-. The characteristic orientations of ions in a closely packed monolayer are found. It is shown that the formation of a closely packed monolayer is possible for [DCA]- and [BF4]- anions only at surface charges that exceed the limit of the electrochemical stability of the corresponding ionic liquids. For the [TBA]+ cation, a monolayer structure can be observed at the charge of nearly 30 μC/cm2 attainable in electrochemical experiment.

Comparative studies of the laser Thomson scattering and Langmuir probe methods for measurements of negative ion density in a glow discharge plasma

International Nuclear Information System (INIS)

Noguchi, M; Hirao, T; Shindo, M; Sakurauchi, K; Yamagata, Y; Uchino, K; Kawai, Y; Muraoka, K

2003-01-01

The newly developed method of the negative ion density measurement in a plasma by laser Thomson scattering (LTS) was checked by comparing the obtained results against an independent technique, namely the Langmuir probe method. Both measurements were performed at the same position of the same inductively coupled plasma. The results agree quite well with each other and this has given confidence in the LTS method of negative ion density measurement. At the same time, both methods are complementary to each other, because the Langmuir probe measurement requires knowledge of the positive ion mass number

Density and potential measurements in an intense ion-beam-generated plasma

International Nuclear Information System (INIS)

Abt, N.E.

1982-05-01

Neutral beams are created by intense large area ion beams which are neutralized in a gas cell. The interaction of the beam with the gas cell creates a plasma. Such a plasma is studied here. The basic plasma parameters, electron temperature, density, and plasma potential, are measured as a function of beam current and neutral gas pressure. These measurements are compared to a model based on the solution of Poisson's equation. Because of the cylindrical geometry the equation cannot be solved analytically. Details of the numerical method are presented

Nernst-Planck modeling of multicomponent ion transport in a Nafion membrane at high current density

NARCIS (Netherlands)

Moshtari Khah, S.; Oppers, N.A.W.; de Groot, M.T.; Keurentjes, J.T.F.; Schouten, J.C.; van der Schaaf, J.

A mathematical model of multicomponent ion transport through a cation-exchange membrane is developed based on the Nernst–Planck equation. A correlation for the non-linear potential gradient is derived from current density relation with fluxes. The boundary conditions are determined with the Donnan

The impact of edge gradients in the pressure, density, ion temperature, and electron temperature on edge-localized modes

International Nuclear Information System (INIS)

Kleva, Robert G.; Guzdar, Parvez N.

2011-01-01

The magnitude of the energy and particle fluxes in simulations of edge-localized modes (ELMs) is determined by the edge gradients in the pressure, density, ion temperature, and electron temperature. The total edge pressure gradient is the dominant influence on ELMs by far. An increase (decrease) of merely 2% in the pressure gradient results in an increase (decrease) of more than a factor of ten in the size of the ELM bursts. At a fixed pressure gradient, the size of the ELM bursts decreases as the density gradient increases, while the size of the bursts increases as the electron temperature gradient or, especially, the ion temperature gradient increases.

Resonance hairpin and Langmuir probe-assisted laser photodetachment measurements of the negative ion density in a pulsed dc magnetron discharge

Energy Technology Data Exchange (ETDEWEB)

Bradley, James W.; Dodd, Robert; You, S.-D.; Sirse, Nishant; Karkari, Shantanu Kumar [Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool (United Kingdom); National Centre for Plasma Science and Technology, Dublin City University, Dublin 9, Republic of Ireland (Ireland); National Centre for Plasma Science and Technology, Dublin City University, Dublin 9, Republic of Ireland and Institute for Plasma Research, Bhat Gandhinagar, Gujarat (India)

2011-05-15

The time-resolved negative oxygen ion density n{sub -} close to the center line in a reactive pulsed dc magnetron discharge (10 kHz and 50% duty cycle) has been determined for the first time using a combination of laser photodetachment and resonance hairpin probing. The discharge was operated at a power of 50 W in 70% argon and 30% oxygen gas mixtures at 1.3 Pa pressure. The results show that the O{sup -} density remains pretty constant during the driven phase of the discharge at values typically below 5x10{sup 14} m{sup -3}; however, in the off-time, the O{sup -} density grows reaching values several times those in the on-time. This leads to the negative ion fraction (or degree of electronegativity) {alpha}=n{sub -}/n{sub e} being higher in the off phase (maximum value {alpha}{approx}1) than in the on phase ({alpha}=0.05-0.3). The authors also see higher values of {alpha} at positions close to the magnetic null than in the more magnetized region of the plasma. This fractional increase in negative ion density during the off-phase is attributed to the enhanced dissociative electron attachment of highly excited oxygen molecules in the cooling plasma. The results show that close to the magnetic null the photodetached electron density decays quickly after the laser pulse, followed by a slow decay over a few microseconds governed by the negative ion temperature. However, in the magnetized regions of the plasma, this decay is more gradual. This is attributed to the different cross-field transport rates for electrons in these two regions. The resonance hairpin probe measurements of the photoelectron densities are compared directly to photoelectron currents obtained using a conventional Langmuir probe. There is good agreement in the general trends, particularly in the off-time.

Normal axonal ion channel function in large peripheral nerve fibers following chronic ciguatera sensitization.

Science.gov (United States)

Vucic, Steve; Kiernan, Matthew C

2008-03-01

Although the acute clinical effects of ciguatera poisoning, due to ingestion of ciguatoxin, are mediated by activation of transient Na+ channels, the mechanisms underlying ciguatera sensitization remain undefined. Axonal excitability studies were performed by stimulating the median motor and sensory nerves in two patients with ciguatera sensitization. Excitability parameters were all within normal limits, thereby arguing against dysfunction of axonal membrane ion channels in large-diameter fibers in ciguatera sensitization.

Effect of Ar ion on the surface properties of low density polyethylene

Science.gov (United States)

Zaki, M. F.

2016-04-01

In this paper, low-density polyethylene (LDPE) was irradiated by argon ion with different fluences up to 1015ions/cm2. The optical, chemical and hardness properties have been investigated using UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and micro-indentation tester, respectively. The results showed the ion beam bombardment induced decreases in the transmittance of the irradiated polymer samples. This change in transmittance can be attributed to the formation of conjugated bonds i.e. possible formation of defects and/or carbon clusters. The indirect optical band gap decreased from 3.0 eV for the pristine sample to 2.3 eV for that sample irradiated with the highest fluence of the Ar ion beam. Furthermore, the number of carbon atoms and clusters increased with increasing Ar ion fluences. FTIR spectra showed the formation of new bands of the bombarded polymer samples. Furthermore, polar groups were created on the surface of the irradiated samples which refer to the increase of the hydrophilic nature of the surface of the irradiated samples. The Vicker's hardness increased from 4.9 MPa for the pristine sample to 17.9 MPa for those bombarded at the highest fluence. This increase is attributed to the increase in the crosslinking and alterations of the bombarded surface into hydrogenated amorphous carbon, which improves the hardness of the irradiated samples. The bombarded LDPE surfaces may be used in special applications to the field of the micro-electronic devices and shock absorbers.

Anisotropic dislocation loop nucleation in ion-irradiated MgAl2O4

International Nuclear Information System (INIS)

Zinkle, S.J.

1991-01-01

Polycrystalline disks of stoichiometric magnesium aluminate spinel (MgAl 2 O 4 ) were irradiated with 2 MeV Al + ions at 650 degrees C and subsequently analyzed in cross-section using transmission electron microscopy (TEM). Interstitial dislocation loops were observed on 110 and 11 habit planes. The population of loops on both sets of habit planes was strongly dependent on their orientation with respect to the ion beam direction. The density of loops with habit plane normals nearly perpendicular to the ion beam direction much higher than loops with habit plane normals nearly parallel to the ion beam direction. On the other hand, the loop size was nearly independent of habit plane orientation. This anisotropic loop nucleation does not occur in ion-irradiated metals such as copper. An additional anomaly associated with ion-irradiated spinel is that the loops on 111 planes were partially unfaulted with a Burgers vector of b = a/4 . Previous neutron irradiation studies have never reported unfaulted loops in stoichiometric spinel. Possible cause of the unusual response of spinel to ion irradiation are discussed. 12 refs., 14 figs

Characterization of low density carbon foams by x-ray computed tomography (CT) and ion microtomography (IMF)

International Nuclear Information System (INIS)

Moddeman, W.E.; Kramer, D.P.; Firsich, D.W.; Trainer, P.D.; Yancy, R.N.; Weirup, D.L.; Logan, C.M.; Pontau, A.E.; Antolak, A.J.; Morse, D.H.

1990-01-01

Two NDT techniques were used to characterize low-density, microcellular, carbon foams fabricated from a salt replica process. In this paper the two techniques are x-ray computed tomography (CT) and ion microtomography (IMT); data are presented on carbon foams that contain high-density regions. The data show that densities which differ by 3 ) materials. The data reveal that the carbon foams produced by this replica process have small density variations; the density being ∼30% greater at the outer edges than when compared to the interior of the foam. In addition, the density gradient is found to be rather sharp, that is the density drops-off rapidly from the outer edges to a uniform one in the interior of the foam. This edge build-up in carbon density was explained in terms of polymer concentrating on the foam exterior during drying which immediately followed a polymer infusion processing step. Supporting analytical data from other techniques show the foam material to be >88.8% carbon

The disparate impact of the ion temperature gradient and the density gradient on edge transport and the low-high transition in tokamaks

International Nuclear Information System (INIS)

Kleva, Robert G.; Guzdar, Parvez N.

2009-01-01

Steepening of the ion temperature gradient in nonlinear fluid simulations of the edge region of a tokamak plasma causes a rapid degradation in confinement. As the density gradient steepens, there is a continuous improvement in confinement analogous to the low (L) to high (H) transition observed in tokamaks. In contrast, as the ion temperature gradient steepens, there is a rapid increase in the particle and energy fluxes and no L-H transition. For a given pressure gradient, confinement always improves when more of the pressure gradient arises from the density gradient, and less of the pressure gradient arises from the ion temperature gradient.

Anisotropic dislocation loop nucleation in ion-irradiated MgAl2O4

International Nuclear Information System (INIS)

Zinkle, S.J.

1992-01-01

This work is intended to investigate the effects of transmutation products and varying ionizing-to-displacive damage ratio on microstructural evolution in ceramics for fusion machine. Polycrystalline disks of stoichiometric magnesium aluminate spinel (MgAl 2 O 4 ) were irradiated with 2 MeV Al + ions at 650C and subsequently analyzed in cross section using transmission electron microscopy (TEM). Interstitial dislocation loops were observed on [110] and [111] habit planes. The population of loops on both sets of habit planes was strongly dependent on their orientation with respect to the ion beam direction. The density of loops with habit plane normals nearly perpendicular to the ion beam direction was much higher than loops with habit plane normals nearly parallel to the ion beam direction. On the other hand, the loop size was nearly independent of habit plane orientation. This anisotropic loop nucleation does not occur in ion-irradiated metals such as copper and may be associated with the structure of displacement cascades in ceramics

Ion mixing and numerical simulation of different ions produced in the ECR ion source

International Nuclear Information System (INIS)

Shirkov, G.D.

1996-01-01

This paper is to continue theoretical investigations and numerical simulations in the physics of ECR ion sources within the CERN program on heavy ion acceleration. The gas (ion) mixing effect in ECR sources is considered here. It is shown that the addition of light ions to the ECR plasma has three different mechanisms to improve highly charged ion production: the increase of confinement time and charge state of highly ions as the result of ion cooling; the concentration of highly charged ions in the central region of the source with high energy and density of electrons; the increase of electron production rate and density of plasma. The numerical simulations of lead ion production in the mixture with different light ions and different heavy and intermediate ions in the mixture with oxygen, are carried out to predict the principal ECR source possibilities for LHC applications. 18 refs., 23 refs

Atomic processes, cross sections, and reaction rates necessary for modelling hydrogen-negative-ion sources and identification of optimum H- current densities

International Nuclear Information System (INIS)

Hiskes, J.R.

1991-01-01

The principal electron excitation cross sections for vibrational excitation in a hydrogen discharge are reported. In the first chamber of a two-chamber hydrogen negative-ion-source system subject to the beam-line constraint of a maximum gas pressure, the density of vibrationally excited molecules reaches an asymptote for increasing discharge current or the equivalent fast electron density. Operating near this first-chamber asymptote, there exists a spatially-dependent maximum negative-ion density in the second chamber. With the extraction grid placed at this maximum the optimum performance of a hydrogen-based system is determined. This optimum performance provides a criterion for the selection of differing source types for fusion applications

Self-consistent-field calculations of atoms and ions using a modified local-density approximation

International Nuclear Information System (INIS)

Liberman, D.A.; Albritton, J.R.; Wilson, B.G.; Alley, W.E.

1994-01-01

Local-density-approximation calculations of atomic structure are useful for the description of atoms and ions in plasmas. The large number of different atomic configurations that exist in typical plasmas leads one to consider the expression of total energies in terms of a Taylor series in the orbital occupation numbers. Two schemes for computing the second derivative Taylor-series coefficients are given; the second, and better one, uses the linear response method developed by Zangwill and Soven [Phys. Rev. A 21, 1561 (1980)] for the calculation of optical response in atoms. A defect in the local-density approximation causes some second derivatives involving Rydberg orbitals to be infinite. This is corrected by using a modified local-density approximation that had previously been proposed [Phys. Rev. B 2, 244 (1970)

Energetic heavy ions accelerate differentiation in the descendants of irradiated normal human diploid fibroblasts

International Nuclear Information System (INIS)

Hamada, Nobuyuki; Hara, Takamitsu; Funayama, Tomoo; Sakashita, Tetsuya; Kobayashi, Yasuhiko

2008-01-01

Ionizing radiation-induced genomic instability has been demonstrated in a variety of endpoints such as delayed reproductive death, chromosome instability and mutations, which occurs in the progeny of survivors many generations after the initial insult. Dependence of these effects on the linear energy transfer (LET) of the radiation is incompletely characterized; however, our previous work has shown that delayed reductions in clonogenicity can be most pronounced at LET of 108 keV/μm. To gain insight into potential cellular mechanisms involved in LET-dependent delayed loss of clonogenicity, we investigated morphological changes in colonies arising from normal human diploid fibroblasts exposed to γ-rays or energetic carbon ions (108 keV/μm). Exposure of confluent cultures to carbon ions was 4-fold more effective at inactivating cellular clonogenic potential and produced more abortive colonies containing reduced number of cells per colony than γ-rays. Second, colonies were assessed for clonal morphotypic heterogeneity. The yield of differentiated cells was elevated in a dose- and LET-dependent fashion in clonogenic colonies, whereas differentiated cells predominated to a comparable extent irrespective of radiation type or dose in abortive colonies. The incidence of giant or multinucleated cells was also increased but much less frequent than that of differentiated cells. Collectively, our results indicate that carbon ions facilitate differentiation more effectively than γ-rays as a major response in the progeny of irradiated fibroblasts. Accelerated differentiation may account, at least in part, for dose- and LET-dependent delayed loss of clonogenicity in normal human diploid cells, and could be a defensive mechanism that minimizes further expansion of aberrant cells

Symmetry energy, its density slope, and neutron-proton effective mass splitting at normal density extracted from global nucleon optical potentials

International Nuclear Information System (INIS)

Xu Chang; Li Baoan; Chen Liewen

2010-01-01

Based on the Hugenholtz-Van Hove theorem, it is shown that both the symmetry energy E sym (ρ) and its density slope L(ρ) at normal density ρ 0 are completely determined by the nucleon global optical potentials. The latter can be extracted directly from nucleon-nucleus scatterings, (p,n) charge-exchange reactions, and single-particle energy levels of bound states. Averaging all phenomenological isovector nucleon potentials constrained by world data available in the literature since 1969, the best estimates of E sym (ρ 0 )=31.3 MeV and L(ρ 0 )=52.7 MeV are simultaneously obtained. Moreover, the corresponding neutron-proton effective mass splitting in neutron-rich matter of isospin asymmetry δ is estimated to be (m n * -m p * )/m=0.32δ.

Swift heavy ion irradiation effects on carbonyl and trans-vinylene groups in high and low density polyethylene

International Nuclear Information System (INIS)

Grosso, M.F. del; Chappa, V.C.; Arbeitman, C.R.; Garcia Bermudez, G.; Behar, M.

2009-01-01

In this work, we have studied the effects of swift heavy ion irradiation on the creation of new functional groups in high and low density polyethylene (HDPE and LDPE). Polymers were irradiated with different ions (6.77 MeV He and 47 MeV Li) and fluences. The induced changes were analyzed by Fourier transform infrared (FTIR) spectroscopy. Creation and damage cross sections for some groups were compared for two different types of PE.

Swift heavy ion irradiation effects on carbonyl and trans-vinylene groups in high and low density polyethylene

Energy Technology Data Exchange (ETDEWEB)

Grosso, M.F. del, E-mail: delgrosso@tandar.cnea.gov.a [Gerencia de Investigacion y Aplicaciones, TANDAR-CNEA (Argentina); Chappa, V.C. [Gerencia de Investigacion y Aplicaciones, TANDAR-CNEA (Argentina); CONICET (Argentina); Arbeitman, C.R. [Gerencia de Investigacion y Aplicaciones, TANDAR-CNEA (Argentina); Garcia Bermudez, G. [Gerencia de Investigacion y Aplicaciones, TANDAR-CNEA (Argentina); CONICET (Argentina); Escuela de Ciencia y Tecnologia, UNSAM (Argentina); Behar, M. [Instituto de Fisica, UFRGS, Porto Alegre (Brazil)

2009-10-01

In this work, we have studied the effects of swift heavy ion irradiation on the creation of new functional groups in high and low density polyethylene (HDPE and LDPE). Polymers were irradiated with different ions (6.77 MeV He and 47 MeV Li) and fluences. The induced changes were analyzed by Fourier transform infrared (FTIR) spectroscopy. Creation and damage cross sections for some groups were compared for two different types of PE.

Orientation-dependent ion beam sputtering at normal incidence conditions in FeSiAl alloy

International Nuclear Information System (INIS)

Batic, Barbara Setina; Jenko, Monika

2010-01-01

The authors have performed Ar+ broad ion beam sputtering of a polycrystalline Fe-Si-Al alloy at normal incidence at energies varying from 6 to 10 keV. Sputtering results in the formation of etch pits, which can be classified in three shapes: triangular, rectangular, and square. As each grain of individual orientation exhibits a certain type of pattern, the etch pits were correlated with the crystal orientations by electron backscattered diffraction technique.

Probing the density dependence of the symmetry potential in intermediate-energy heavy ion collisions

International Nuclear Information System (INIS)

Li Qingfeng; Li Zhuxia; Soff, Sven; Gupta, Raj K; Bleicher, Marcus; Stoecker, Horst

2005-01-01

Based on the ultrarelativistic quantum molecular dynamics model, the effects of the density-dependent symmetry potential for baryons and of the Coulomb potential for produced mesons are investigated for neutron-rich heavy ion collisions at intermediate energies. The calculated results of the Δ - /Δ ++ and π - /π + production ratios show a clear beam-energy dependence on the density-dependent symmetry potential, which is stronger for the π - /π + ratio close to the pion production threshold. The Coulomb potential of the mesons changes the transverse momentum distribution of the π - /π + ratio significantly, though it alters only slightly the π - and π + total yields. The π - yields, especially at midrapidity or at low transverse momenta and the π - /π + ratios at low transverse momenta are shown to be sensitive probes of the density-dependent symmetry potential in dense nuclear matter. The effect of the density-dependent symmetry potential on the production of both K 0 and K + mesons is also investigated

Realization of a diamond based high density multi electrode array by means of Deep Ion Beam Lithography

International Nuclear Information System (INIS)

Picollo, F.; Battiato, A.; Bernardi, E.; Boarino, L.; Enrico, E.; Forneris, J.; Gatto Monticone, D.; Olivero, P.

2015-01-01

In the present work we report about a parallel-processing ion beam fabrication technique whereby high-density sub-superficial graphitic microstructures can be created in diamond. Ion beam implantation is an effective tool for the structural modification of diamond: in particular ion-damaged diamond can be converted into graphite, therefore obtaining an electrically conductive phase embedded in an optically transparent and highly insulating matrix. The proposed fabrication process consists in the combination of Deep Ion Beam Lithography (DIBL) and Focused Ion Beam (FIB) milling. FIB micromachining is employed to define micro-apertures in the contact masks consisting of thin (<10 μm) deposited metal layers through which ions are implanted in the sample. A prototypical single-cell biosensor was realized with the above described technique. The biosensor has 16 independent electrodes converging inside a circular area of 20 μm diameter (typical neuroendocrine cells size) for the simultaneous recording of amperometric signals

Critical current densities and flux creep rate in Co-doped BaFe2As2 with columnar defects introduced by heavy-Ion irradiation

International Nuclear Information System (INIS)

Nakajima, Y.; Tsuchiya, Y.; Taen, T.; Yagyuda, H.; Tamegai, T.; Okayasu, S.; Sasase, M.; Kitamura, H.; Murakami, T.

2010-01-01

We report the formation of columnar defects in Co-doped BaFe 2 As 2 single crystals with different heavy-ion irradiations. The formation of columnar defects by 200 MeV Au ion irradiation is confirmed by transmission electron microscopy and their density is about 40% of the irradiation dose. Magneto-optical imaging and bulk magnetization measurements reveal that the critical current density J c is enhanced in the 200 MeV Au and 800 MeV Xe ion irradiated samples while J c is unchanged in the 200 MeV Ni ion irradiated sample. We also find that vortex creep rates are strongly suppressed by the columnar defects. We compare the effect of heavy-ion irradiation into Co-doped BaFe 2 As 2 and cuprate superconductors.

Probing the nuclear matter at high baryon and isospin density with heavy ion collisions

International Nuclear Information System (INIS)

Di Toro, M.; Colonna, M.; Ferini, G.

2010-01-01

Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. High Energy Collisions are studied in order to access nuclear matter properties at high density. Particular attention is devoted to the selection of observables sensitive to the poorly known symmetry energy at high baryon density, of large fundamental interest, even for the astrophysics implications. Using fully consistent covariant transport simulations built on effective field theories we are testing isospin observables ranging from nucleon/cluster emissions, collective flows (in particular the elliptic, squeeze out, part) and meson production. The possibility to shed light on the controversial neutron/proton effective mass splitting in asymmetric matter is also stressed. The "symmetry" repulsion at high baryon density will also lead to an "earlier" hadron-deconfinement transition in n-rich matter. The phase transition of hadronic to quark matter at high baryon and isospin density is analyzed. Nonlinear relativistic mean field models are used to describe hadronic matter, and the MIT bag model is adopted for quark matter. The boundaries of the mixed phase and the related critical points for symmetric and asymmetric matter are obtained. Isospin effects appear to be rather significant. The binodal transition line of the (T,ρ B ) diagram is lowered in a region accessible to heavy ion collisions in the energy range of the new planned FAIR/NICA facilities. Some observable effects of the mixed phase are suggested, in particular a neutron distillation mechanism. Theoretically a very important problem appears to be the suitable treatment of the isovector part of the interaction in effective QCD lagrangian approaches. (author)

Ion channel density regulates switches between regular and fast spiking in soma but not in axons.

Directory of Open Access Journals (Sweden)

Hugo Zeberg

2010-04-01

Full Text Available The threshold firing frequency of a neuron is a characterizing feature of its dynamical behaviour, in turn determining its role in the oscillatory activity of the brain. Two main types of dynamics have been identified in brain neurons. Type 1 dynamics (regular spiking shows a continuous relationship between frequency and stimulation current (f-I(stim and, thus, an arbitrarily low frequency at threshold current; Type 2 (fast spiking shows a discontinuous f-I(stim relationship and a minimum threshold frequency. In a previous study of a hippocampal neuron model, we demonstrated that its dynamics could be of both Type 1 and Type 2, depending on ion channel density. In the present study we analyse the effect of varying channel density on threshold firing frequency on two well-studied axon membranes, namely the frog myelinated axon and the squid giant axon. Moreover, we analyse the hippocampal neuron model in more detail. The models are all based on voltage-clamp studies, thus comprising experimentally measurable parameters. The choice of analysing effects of channel density modifications is due to their physiological and pharmacological relevance. We show, using bifurcation analysis, that both axon models display exclusively Type 2 dynamics, independently of ion channel density. Nevertheless, both models have a region in the channel-density plane characterized by an N-shaped steady-state current-voltage relationship (a prerequisite for Type 1 dynamics and associated with this type of dynamics in the hippocampal model. In summary, our results suggest that the hippocampal soma and the two axon membranes represent two distinct kinds of membranes; membranes with a channel-density dependent switching between Type 1 and 2 dynamics, and membranes with a channel-density independent dynamics. The difference between the two membrane types suggests functional differences, compatible with a more flexible role of the soma membrane than that of the axon membrane.

Low-density lipoprotein concentration in the normal left coronary artery tree

Directory of Open Access Journals (Sweden)

Louridas George E

2008-10-01

Full Text Available Abstract Background The blood flow and transportation of molecules in the cardiovascular system plays a crucial role in the genesis and progression of atherosclerosis. This computational study elucidates the Low Density Lipoprotein (LDL site concentration in the entire normal human 3D tree of the LCA. Methods A 3D geometry model of the normal human LCA tree is constructed. Angiographic data used for geometry construction correspond to end-diastole. The resulted model includes the LMCA, LAD, LCxA and their main branches. The numerical simulation couples the flow equations with the transport equation applying realistic boundary conditions at the wall. Results High concentration of LDL values appears at bifurcation opposite to the flow dividers in the proximal regions of the Left Coronary Artery (LCA tree, where atherosclerosis frequently occurs. The area-averaged normalized luminal surface LDL concentrations over the entire LCA tree are, 1.0348, 1.054 and 1.23, for the low, median and high water infiltration velocities, respectively. For the high, median and low molecular diffusivities, the peak values of the normalized LDL luminal surface concentration at the LMCA bifurcation reach 1.065, 1.080 and 1.205, respectively. LCA tree walls are exposed to a cholesterolemic environment although the applied mass and flow conditions refer to normal human geometry and normal mass-flow conditions. Conclusion The relationship between WSS and luminal surface concentration of LDL indicates that LDL is elevated at locations where WSS is low. Concave sides of the LCA tree exhibit higher concentration of LDL than the convex sides. Decreased molecular diffusivity increases the LDL concentration. Increased water infiltration velocity increases the LDL concentration. The regional area of high luminal surface concentration is increased with increasing water infiltration velocity. Regions of high LDL luminal surface concentration do not necessarily co-locate to the

Reduction in life span on normal human fibroblasts exposed to low-dose radiation in heavy-ion radiation field

International Nuclear Information System (INIS)

Suzuki, Masao; Yamaguchi, Chizuru; Yasuda, Hiroshi; Uchihori, Yukio; Fujitaka, Kazunobu

2003-01-01

We studied the effect of in vitro life span in normal human fibroblasts exposed to chronically low-dose radiation in heavy-ion radiation field. Cells were cultured in a CO 2 incubator, which was set in the irradiation room for biological study of heavy ions in the Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences (NIRS), and exposed to scattered radiations produced with heavy-ion beams throughout the life span of the cell population. Absorbed dose, which was measured using a thermoluminescence dosimeter(TLD) and a Si-semiconductor detector, was to be 1.4 mGy per day when operating the HIMAC machine for biological experiments. The total population doubling number of the exposed cells reduced to 79-93% of non-exposed control cells in the three independent experiments. There is evidence that the exposure of chronically low-dose radiation in heavy-ion radiation field promotes the life-span reduction in cellular level. (author)

Collective focusing ion accelerator

International Nuclear Information System (INIS)

Goldin, F.J.

1986-01-01

The principal subject of this dissertation is the trapping confinement of pure electron plasmas in bumpy toroidal magnetic fields, with particular attention given to the trapping procedure and the behavior of the plasma during the final equilibrium. The most important aspects of the equilibrium studied were the qualitative nature of the plasma configuration and motion and its density, distribution and stability. The motivation for this study was that an unneutralized cloud of electrons contained in a toroidal system, sufficiently dense and stable, may serve to electrostatically focus ions (against centrifugal and self space charge forces) in a cyclic ion accelerator. Such an accelerator, known as a Collective Focusing Ion Accelerator (CFIA) could be far smaller than conventional designs (which use external magnetic fields directly to focus the ions) due to the smaller gyro-radium of an electron in a magnetic field of given strength. The electron cloud generally drifted poloidally at a finite radius from the toroidal minor axis. As this would preclude focusing ions with such clouds, damping this motion was investigated. Finite resistance in the normally perfectly conductive vessel wall did this. In further preparation for a working CFIA, additional experiments studied the effect of ions on the stability of the electron cloud

Electrical characterization of single cells using polysilicon wire ion sensor in an isolation window.

Science.gov (United States)

Wu, You-Lin; Hsu, Po-Yen; Hsu, Chung-Ping; Wang, Chih-Cheng; Lee, Li-Wen; Lin, Jing-Jenn

2011-10-01

A polysilicon wire (PSW) sensor can detect the H(+) ion density (pH value) of the medium coated on its surface, and different cells produce different extracellular acidification and hence different H(+) ion densities. Based on this, we used a PSW sensor in combination with a mold-cast polydimethylsiloxane (PDMS) isolation window to detect the adhesion, apoptosis and extracellular acidification of single normal cells and single cancer cells. Single living human normal cells WI38, MRC5, and BEAS-2B as well as non-small-cell lung cancer (NSCLC) cells A549, H1299, and CH27 were cultivated separately inside the isolation window. The current flowing through the PSW channel was measured. From the PSW channel current change as a function of time, we determined the cell adhesion time by observing the time required for the current change to saturate, since a stable extracellular ion density was established after the cells were completely adhered to the PSW surface. The apoptosis of cells can also be determined when the channel current change drops to zero. We found that all the NSCLC cells had a higher channel current change and hence a lower pH value than the normal cells anytime after they were seeded. The corresponding average pH values were 5.86 for A549, 6.00 for H1299, 6.20 for CH27, 6.90 for BEAS-2B, 6.96for MRC5, and 7.02 for WI38, respectively, after the cells were completely adhered to the PSW surface. Our results show that NSCLC cells have a stronger cell-substrate adhesion and a higher extracellular acidification rate than normal cells.

The small-molecule Bcl-2 inhibitor HA14-1 sensitizes cervical cancer cells, but not normal fibroblasts, to heavy-ion radiation

International Nuclear Information System (INIS)

Hamada, Nobuyuki; Kataoka, Keiko; Sora, Sakura; Hara, Takamitsu; Omura-Minamisawa, Motoko; Funayama, Tomoo; Sakashita, Tetsuya; Nakano, Takashi; Kobayashi, Yasuhiko

2008-01-01

This is the first study to demonstrate that the small-molecule Bcl-2 inhibitor HA14-1 renders human cervical cancer cells and their Bcl-2 overexpressing radioresistant counterparts, but not normal fibroblasts, more susceptible to heavy ions. Thus, Bcl-2 may be an attractive target for improving the efficacy of heavy-ion therapy

Influence of Electrode Density on the Performance of Li-Ion Batteries: Experimental and Simulation Results

Directory of Open Access Journals (Sweden)

Jelle Smekens

2016-02-01

Full Text Available Lithium-ion battery (LIB technology further enabled the information revolution by powering smartphones and tablets, allowing these devices an unprecedented performance against reasonable cost. Currently, this battery technology is on the verge of carrying the revolution in road transport and energy storage of renewable energy. However, to fully succeed in the latter, a number of hurdles still need to be taken. Battery performance and lifetime constitute a bottleneck for electric vehicles as well as stationary electric energy storage systems to penetrate the market. Electrochemical battery models are one of the engineering tools which could be used to enhance their performance. These models can help us optimize the cell design and the battery management system. In this study, we evaluate the ability of the Porous Electrode Theory (PET to predict the effect of changing positive electrode density in the overall performance of Li-ion battery cells. It can be concluded that Porous Electrode Theory (PET is capable of predicting the difference in cell performance due to a changing positive electrode density.

Ion cyclotron modes in a low density plasma cavity. Part I: Theory

International Nuclear Information System (INIS)

Sawley, M.L.

1990-12-01

Ion cyclotron modes excited in a low density, cylindrical plasma cavity using an external inductive antenna are investigated theoretically. These modes, which have a long parallel wavelength, exhibit a strong electrostatic character and are only weakly coupled to the antenna fields. It is shown that, despite the low frequency considered, electron dynamics play a dominant role via the effects of both Landau damping and electron inertia. The characteristics of the wavefields associated with these modes, relevant to an experimental investigation, are described. (author) 8 figs., 1 tab., 10 refs

Ion-acoustic double layers in multi-species plasmas maintained by negative ions

International Nuclear Information System (INIS)

Verheest, F.

1989-01-01

A study is made of ion-acoustic double layers in a plasma consisting of any number of cold positive and negative ion (and cold electron) species in addition to one isothermal electron population. The Sagdeev potential is obtained in general, together with limits on both compressive and rarefactive solutions for ion-acoustic double layers and/or solitons. Weak ion-acoustic double layers are described by a modified Korteweg-de Vries equation. Such double layers are not possible in plasmas with only positive ion species and one electron population. When one or more negative ion and/or cold electron species are included above a certain threshold density, rarefactive ion-acoustic double layers occur, but no compressive ones. The double-layer form of the potential is given, together with an application to a plasma with one positive and one negative ion component. It is shown that there is indeed such a threshold density for the negative ion density, depending on the charge-to-mass ratios of both types of ions. The threshold density is determined numerically for a range of such ratios and discussed in view of possible relevance to auroral and experimental plasmas. In the discussion, cold electrons can play the role of the negative ion species. (author)

Ion beam enhancement in magnetically insulated ion diodes for high-intensity pulsed ion beam generation in non-relativistic mode

Energy Technology Data Exchange (ETDEWEB)

Zhu, X. P. [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024 (China); Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Zhang, Z. C.; Lei, M. K., E-mail: surfeng@dlut.edu.cn [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Pushkarev, A. I. [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Laboratory of Beam and Plasma Technology, High Technologies Physics Institute, Tomsk Polytechnic University, 30, Lenin Ave, 634050 Tomsk (Russian Federation)

2016-01-15

High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, taking into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200–300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation.

On the asymptotic improvement of supervised learning by utilizing additional unlabeled samples - Normal mixture density case

Science.gov (United States)

Shahshahani, Behzad M.; Landgrebe, David A.

1992-01-01

The effect of additional unlabeled samples in improving the supervised learning process is studied in this paper. Three learning processes. supervised, unsupervised, and combined supervised-unsupervised, are compared by studying the asymptotic behavior of the estimates obtained under each process. Upper and lower bounds on the asymptotic covariance matrices are derived. It is shown that under a normal mixture density assumption for the probability density function of the feature space, the combined supervised-unsupervised learning is always superior to the supervised learning in achieving better estimates. Experimental results are provided to verify the theoretical concepts.

'Beam-emission spectroscopy' diagnostics also measure edge fast-ion light

International Nuclear Information System (INIS)

Heidbrink, W W; Bortolon, A; McKee, G R; Smith, D R

2011-01-01

Beam-emission spectroscopy (BES) diagnostics normally detect fluctuations in the light emitted by an injected neutral beam. Under some circumstances, however, light from fast ions that charge exchange in the high neutral-density region at the edge of the plasma make appreciable contributions to the BES signals. This 'passive' fast-ion D α (FIDA) light appears in BES signals from both the DIII-D tokamak and the National Spherical Torus Experiment (NSTX). One type of passive FIDA light is associated with classical orbits that traverse the edge. Another type is caused by instabilities that expel fast ions from the core; this light can complicate measurement of the instability eigenfunction.

Density functional study of isoguanine tetrad and pentad sandwich complexes with alkali metal ions.

Science.gov (United States)

Meyer, Michael; Steinke, Thomas; Sühnel, Jürgen

2007-02-01

Isoguanine tetraplexes and pentaplexes contain two or more stacked polyads with intercalating metal ions. We report here the results of a density functional study of sandwiched isoguanine tetrad and pentad complexes consisting of two polyads with Na(+), K(+) and Rb(+) ions at the B3LYP level. In comparison to single polyad metal ion complexes, there is a trend towards increased non-planarity of the polyads in the sandwich complexes. In general, the pentad sandwiches have relatively planar polyad structures, whereas the tetrad complexes contain highly non-planar polyad building blocks. As in other sandwich complexes and in metal ion complexes with single polyads, the metal ion-base interaction energy plays an essential role. In iG sandwich structures, this interaction energy is slightly larger than in the corresponding guanine sandwich complexes. Because the base-base interaction energy is even more increased in passing from guanine to isoguanine, the isoguanine sandwiches are thus far the only examples where the base-base interaction energy is larger than the base-metal ion interaction energy. Stacking interactions have been studied in smaller models consisting of two bases, retaining the geometry from the complete complex structures. From the data obtained at the B3LYP and BH&H levels and with Møller-Plesset perturbation theory, one can conclude that the B3LYP method overestimates the repulsion in stacked base dimers. For the complexes studied in this work, this is only of minor importance because the direct inter-tetrad or inter-pentad interaction is supplemented by a strong metal ion-base interaction. Using a microsolvation model, the metal ion preference K(+) approximately Rb(+) > Na(+) is found for tetrad complexes. On the other hand, for pentads the ordering is Rb(+) > K(+) > Na(+). In the latter case experimental data are available that agree with this prediction.

Enhanced ion acceleration in transition from opaque to transparent plasmas

Science.gov (United States)

Mishra, R.; Fiuza, F.; Glenzer, S.

2018-04-01

Using particle-in-cell simulations, we investigate ion acceleration in the interaction of high intensity lasers with plasmas which transition from opaque to transparent during the interaction process. We show that the highest ion energies are achieved when the laser traverses the target around the peak intensity and re-heats the electron population responsible for the plasma expansion, enhancing the corresponding sheath electric field. This process can lead to an increase of up to 2x in ion energy when compared with the standard Target Normal Sheath Acceleration in opaque targets under the same laser conditions. A theoretical model is developed to predict the optimal target areal density as a function of laser intensity and pulse duration. A systematic parametric scan for a wide range of target densities and thicknesses is performed in 1D, 2D and 3D and shown consistent with the theory and with recent experimental results. These results open the way for a better optimization of the ion energy in future laser–solid experiments.

Development of intense pulsed heavy ion beam diode using gas puff plasma gun as ion source

International Nuclear Information System (INIS)

Ito, H.; Higashiyama, M.; Takata, S.; Kitamura, I.; Masugata, K.

2006-01-01

A magnetically insulated ion diode with an active ion source of a gas puff plasma gun has been developed in order to generate a high-intensity pulsed heavy ion beam for the implantation process of semiconductors and the surface modification of materials. The nitrogen plasma produced by the plasma gun is injected into the acceleration gap of the diode with the external magnetic field system. The ion diode is operated at diode voltage approx. =200 kV, diode current approx. =2 kA and pulse duration approx. =150 ns. A new acceleration gap configuration for focusing ion beam has been designed in order to enhance the ion current density. The experimental results show that the ion current density is enhanced by a factor of 2 and the ion beam has the ion current density of 27 A/cm 2 . In addition, the coaxial type Marx generator with voltage 200 kV and current 15 kA has been developed and installed in the focus type ion diode. The ion beam of ion current density approx. =54 A/cm 2 is obtained. To produce metallic ion beams, an ion source by aluminum wire discharge has been developed and the aluminum plasma of ion current density ∼70 A/cm 2 is measured. (author)

Cassini Ion Mass Spectrometer Peak Calibrations from Statistical Analysis of Flight Data

Science.gov (United States)

Woodson, A. K.; Johnson, R. E.

2017-12-01

The Cassini Ion Mass Spectrometer (IMS) is an actuating time-of-flight (TOF) instrument capable of resolving ion mass, energy, and trajectory over a field of view that captures nearly the entire sky. One of three instruments composing the Cassini Plasma Spectrometer, IMS sampled plasma throughout the Kronian magnetosphere from 2004 through 2012 when it was permanently disabled due to an electrical malfunction. Initial calibration of the flight instrument at Southwest Research Institute (SwRI) was limited to a handful of ions and energies due to time constraints, with only about 30% of planned measurements carried out prior to launch. Further calibration measurements were subsequently carried out after launch at SwRI and Goddard Space Flight Center using the instrument prototype and engineering model, respectively. However, logistical differences among the three calibration efforts raise doubts as to how accurately the post-launch calibrations describe the behavior of the flight instrument. Indeed, derived peak parameters for some ion species differ significantly from one calibration to the next. In this study we instead perform a statistical analysis on 8 years of flight data in order to extract ion peak parameters that depend only on the response of the flight instrument itself. This is accomplished by first sorting the TOF spectra based on their apparent compositional similarities (e.g. primarily water group ions, primarily hydrocarbon ions, etc.) and normalizing each spectrum. The sorted, normalized data are then binned according to TOF, energy, and counts in order to generate energy-dependent probability density maps of each ion peak contour. Finally, by using these density maps to constrain a stochastic peak fitting algorithm we extract confidence intervals for the model parameters associated with various measured ion peaks, establishing a logistics-independent calibration of the body of IMS data gathered over the course of the Cassini mission.

Peculiarity of deuterium ions interaction with tungsten surface in the condition imitating combination of normal operation with plasma disruption in ITER

Energy Technology Data Exchange (ETDEWEB)

Guseva, M.I. E-mail: martyn@nfi.kiae.ru; Vasiliev, V.I.; Gureev, V.M.; Danelyan, L.S.; Khirpunov, B.I.; Korshunov, S.N.; Kulikauskas, V.S.; Martynenko, Yu.V.; Petrov, V.B.; Strunnikov, V.N.; Stolyarova, V.G.; Zatekin, V.V.; Litnovsky, A.M

2001-03-01

Tungsten is a candidate material for the ITER divertor. For the simulation of ITER normal operation conditions in combination with plasma disruptions samples of various types of tungsten were exposed to both steady-state and high power pulsed deuterium plasmas. Tungsten samples were first exposed in a steady-state plasma with an ion current density {approx}10{sup 21} m{sup -2} s{sup -1} up to a dose of 10{sup 25} m{sup -2} at a temperature of 770 K. The energy of deuterium ions was 150 eV. The additional exposure of the samples to 10 pulses of deuterium plasma was performed in the electrodynamical plasma accelerator with an energy flux 0.45 MJ/m{sup 2} per pulse. Samples of four types of tungsten (W-1%La{sub 2}O{sub 3}, W-13I, monocrystalline W(1 1 1) and W-10%Re) were investigated. The least destruction of the surface was observed for W(1 1 1). The concentration of retained deuterium in tungsten decreased from 2.5x10{sup 19} m{sup -2} to 1.07x10{sup 19} m{sup -2} (for W(1 1 1)) as a result of the additional pulsed plasma irradiation. Investigation of the tungsten erosion products after the high power pulsed plasma shots was also carried out.

Calculation of electronic stopping power along glancing swift heavy ion tracks in perovskites using ab initio electron density data

Energy Technology Data Exchange (ETDEWEB)

Osmani, O; Duvenbeck, A; Akcoeltekin, E; Meyer, R; Schleberger, M [Department of Physics, University of Duisburg-Essen, D-47048 Duisburg (Germany); Lebius, H [CIMAP, blvd Henri Becquerel, 14070 Caen (France)], E-mail: marika.schleberger@uni-due.de

2008-08-06

In recent experiments the irradiation of insulators of perovskite type with swift (E{approx}100 MeV) heavy ions under glancing incidence has been shown to provide a unique means to generate periodically arranged nanodots at the surface. The physical origin of these patterns has been suggested as stemming from a highly anisotropic electron density distribution within the bulk. In order to show the relevance of the electron density distribution of the target we present a model calculation for the system Xe{sup 23+} {yields} SrTiO{sub 3} that is known to produce the aforementioned surface modifications. On the basis of the Lindhard model of electronic stopping, we employ highly-resolved ab initio electron density data to describe the conversion of kinetic energy into excitation energy along the ion track. The primary particle dynamics are obtained via integration of the Newtonian equations of motion that are governed by a space- and time-dependent frictional force originating from Lindhard stopping. The analysis of the local electronic stopping power along the ion track reveals a pronounced periodic structure. The periodicity length varies strongly with the particular choice of the polar angle of incidence and is directly correlated to the experimentally observed formation of periodic nanodots at insulator surfaces.

Maximizing Ion Current by Space Charge Neutralization using Negative Ions and Dust Particles

International Nuclear Information System (INIS)

Smirnov, A.; Raitses, Y.; Fisch, N.J.

2005-01-01

Ion current extracted from an ion source (ion thruster) can be increased above the Child-Langmuir limit if the ion space charge is neutralized. Similarly, the limiting kinetic energy density of the plasma flow in a Hall thruster might be exceeded if additional mechanisms of space charge neutralization are introduced. Space charge neutralization with high-mass negative ions or negatively charged dust particles seems, in principle, promising for the development of a high current or high energy density source of positive light ions. Several space charge neutralization schemes that employ heavy negatively charged particles are considered. It is shown that the proposed neutralization schemes can lead, at best, only to a moderate but nonetheless possibly important increase of the ion current in the ion thruster and the thrust density in the Hall thruster

Stability of Non-Neutral Plasma Cylinder Consisting of Magnetized Cold Electrons and of Small Density Fraction of Ions Born at Rest: Non-Local Analysis

International Nuclear Information System (INIS)

Yeliseyev, Y. N.

2009-01-01

The non-local stability problem of the plasma cylinder, filled with 'cold' magnetized rigidly rotating electrons, and a small density fraction of ions, is solved. The ions are supposed to be born at rest by ionization of background gas. The study is based on the kinetic description of ions. The equilibrium distribution function, taking into account the peculiarity of ions birth, is used. The radial electric field is caused by space charge of non-neutral plasma. The dispersion equation for plasma eigen frequencies is obtained analytically. It is valid within the total admissible range of values of electric and magnetic fields. Normalized eigen frequencies ω'/Ω i are calculated for the basic azimuth mode m = 1(ω' ω-mω i + , ω + = (-ω ci +Ω i )/2, Ω i (ω ci 2 -4eE r /m i r) 1/2 is called the 'modified' ion cyclotron (MIC) frequency), for the density fraction of ions of atomic nitrogen f N i /n e = 0,01 and are presented in graphic form versus parameter 2ω pe 2 /ω ce 2 . The spectra of oscillations ω'/Ω i consist of the family of electron Trivel-piece--Gould (TG) modes and of the families of MIC modes. The frequencies of MIC modes are located in a small vicinity of harmonics of the MIC frequency Ω i above and below the harmonic. The TG modes in non-neutral plasma fall in the region of MIC frequencies Ω i and interact strongly with MIC modes. The slow TG modes become unstable near the crossings with non-negative harmonics of MIC frequencies. The instabilities have a resonant character. The lowest radial TG mode has a maximum growth rate at crossing with a zero harmonic of Ω i ((Im ω'/Ω i ) max ≅0,074). The growth rates of MIC modes are much lower ((Im ω'/Ω i ) max pe 2 /ω ce 2 , corresponding to strong radial electric fields (ω ci 2 r /m i r|), in which the ions are unmagnetized. The oscillations of small amplitude are seen on some frequency dependencies of MIC modes. They are similar to oscillations on dispersion curves of electron waves in

Optimization of superconductor--normal-metal--superconductor Josephson junctions for high critical-current density

International Nuclear Information System (INIS)

Golub, A.; Horovitz, B.

1994-01-01

The application of superconducting Bi 2 Sr 2 CaCu 2 O 8 and YBa 2 Cu 3 O 7 wires or tapes to electronic devices requires the optimization of the transport properties in Ohmic contacts between the superconductor and the normal metal in the circuit. This paper presents results of tunneling theory in superconductor--normal-metal--superconductor (SNS) junctions, in both pure and dirty limits. We derive expressions for the critical-current density as a function of the normal-metal resistivity in the dirty limit or of the ratio of Fermi velocities and effective masses in the clean limit. In the latter case the critical current increases when the ratio γ of the Fermi velocity in the superconductor to that of the weak link becomes much less than 1 and it also has a local maximum if γ is close to 1. This local maximum is more pronounced if the ratio of effective masses is large. For temperatures well below the critical temperature of the superconductors the model with abrupt pair potential on the SN interfaces is considered and its applicability near the critical temperature is examined

Optimum extracted H- and D- current densities from gas-pressure-limited high-power hydrogen/deuterium tandem ion sources

International Nuclear Information System (INIS)

Hiskes, J.R.

1993-01-01

The tandem hydrogen/deuterium ion source is modelled for the purpose of identifying the maximum current densities that can be extracted subject to the gas-pressure constraints proposed for contemporary beam-line systems. Optimum useful extracted current densities are found to be in the range of approximately 7 to 10 mA cm -2 . The sensitivity of these current densities is examined subject to uncertainties in the underlying atomic/molecular rate processes; A principal uncertainty remains the quantification of the molecular vibrational distribution following H 3 + wall collisions

Brightness enhancement of plasma ion source by utilizing anode spot for nano applications

International Nuclear Information System (INIS)

Park, Yeong-Shin; Lee, Yuna; Chung, Kyoung-Jae; Hwang, Y. S.; Kim, Yoon-Jae; Park, Man-Jin; Moon, Dae Won

2012-01-01

Anode spots are known as additional discharges on positively biased electrode immersed in plasmas. The anode spot plasma ion source (ASPIS) has been investigated as a high brightness ion source for nano applications such as focused ion beam (FIB) and nano medium energy ion scattering (nano-MEIS). The generation of anode spot is found to enhance brightness of ion beam since the anode spot increases plasma density near the extraction aperture. Brightness of the ASPIS has been estimated from measurement of emittance for total ion beam extracted through sub-mm aperture. The ASPIS is installed to the FIB system. Currents and diameters of the focused beams with/without anode spot are measured and compared. As the anode spot is turned on, the enhancement of beam current is observed at fixed diameter of the focused ion beam. Consequently, the brightness of the focused ion beam is enhanced as well. For argon ion beam, the maximum normalized brightness of 12 300 A/m 2 SrV is acquired. The ASPIS is applied to nano-MEIS as well. The ASPIS is found to increase the beam current density and the power efficiency of the ion source for nano-MEIS. From the present study, it is shown that the ASPIS can enhance the performance of devices for nano applications.

Silicon nanodot formation and self-ordering under bombardment with heavy Bi3 ions

International Nuclear Information System (INIS)

Boettger, Roman; Heinig, Karl-Heinz; Bischoff, Lothar; Liedke, Bartosz; Huebner, Rene; Pilz, Wolfgang

2013-01-01

Si nanodots of high density and hexagonal short-range order are observed upon normal-incidence bombardment of hot, crystalline Si with Bi 3 + ions having a kinetic energy of a few tens of keV. The heights of nanodots are comparable to their widths of ∝20 nm. The implanted Bi accumulates in tiny Bi nanocrystals in a thin Si top layer which is amorphous due to implantation damage. Light and heavy ions up to Xe cause smoothing of surfaces, but Bi 3 + ions considered here have a much higher mass. Atomistic simulations prove that each Bi 3 + impact deposits an extremely high energy density resulting in a several nanometer large melt pool, which resolidifies within a few hundreds of picoseconds. Experiments confirm that dot patterns form only if the deposited energy density exceeds the threshold for melting. Comparing monatomic and polyatomic Bi ion irradiation, Bi-Si phase separation and preferential ion erosion are ruled out as driving forces of pattern formation. A model based on capillary forces in the melt pool explains the pattern formation consistently. High-density Si nanodots are formed by polyatomic Bi ion irradiation of hot Si surfaces. Each impact causes local transient melt pools smaller than the dots. Hexagonally ordered patterns evolve by self-organization driven by repeated ion-induced melting of tiny volumes. Homogeneously distributed Bi nanocrystals are found in the a-Si film. These nanocrystals are related to particularities of the Si-Bi phase diagram. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Change in equilibrium position of misfit dislocations at the GaN/sapphire interface by Si-ion implantation into sapphire—I. Microstructural characterization

Energy Technology Data Exchange (ETDEWEB)

Lee, Sung Bo, E-mail: bolee@snu.ac.kr; Han, Heung Nam, E-mail: hnhan@snu.ac.kr; Lee, Dong Nyung [Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 151-744 (Korea, Republic of); Ju, Jin-Woo [Korea Photonics Technology Institute, Gwangju 500-779 (Korea, Republic of); Kim, Young-Min; Yoo, Seung Jo; Kim, Jin-Gyu [Korea Basic Science Institute, Daejeon 305-806 (Korea, Republic of)

2015-07-15

Much research has been done to reduce dislocation densities for the growth of GaN on sapphire, but has paid little attention to the elastic behavior at the GaN/sapphire interface. In this study, we have examined effects of the addition of Si to a sapphire substrate on its elastic property and on the growth of GaN deposit. Si atoms are added to a c-plane sapphire substrate by ion implantation. The ion implantation results in scratches on the surface, and concomitantly, inhomogeneous distribution of Si. The scratch regions contain a higher concentration of Si than other regions of the sapphire substrate surface, high-temperature GaN being poorly grown there. However, high-temperature GaN is normally grown in the other regions. The GaN overlayer in the normally-grown regions is observed to have a lower TD density than the deposit on the bare sapphire substrate (with no Si accommodated). As compared with the film on an untreated, bare sapphire, the cathodoluminescence defect density decreases by 60 % for the GaN layer normally deposited on the Si-ion implanted sapphire. As confirmed by a strain mapping technique by transmission electron microscopy (geometric phase analysis), the addition of Si in the normally deposited regions forms a surface layer in the sapphire elastically more compliant than the GaN overlayer. The results suggest that the layer can largely absorb the misfit strain at the interface, which produces the overlayer with a lower defect density. Our results highlight a direct correlation between threading-dislocation density in GaN deposits and the elastic behavior at the GaN/sapphire interface, opening up a new pathway to reduce threading-dislocation density in GaN deposits.

Experimental Evaluation of a Negative Ion Source for a Heavy Ion Fusion Negative Ion Driver

International Nuclear Information System (INIS)

Grisham, L.R.; Hahto, S.K.; Hahto, S.T.; Kwan, J.W.; Leung, K.N.

2004-01-01

Negative halogen ions have recently been proposed as a possible alternative to positive ions for heavy ion fusion drivers because electron accumulation would not be a problem in the accelerator, and if desired, the beams could be photo-detached to neutrals. To test the ability to make suitable quality beams, an experiment was conducted at Lawrence Berkeley National Laboratory using chlorine in an RF-driven ion source. Without introducing any cesium (which is required to enhance negative ion production in hydrogen ion sources) a negative chlorine current density of 45 mA/cm 2 was obtained under the same conditions that gave 57 45 mA/cm 2 of positive chlorine, suggesting the presence of nearly as many negative ions as positive ions in the plasma near the extraction plane. The negative ion spectrum was 99.5% atomic chlorine ions, with only 0.5% molecular chlorine, and essentially no impurities. Although this experiment did not incorporate the type of electron suppression technology that i s used in negative hydrogen beam extraction, the ratio of co-extracted electrons to Cl - was as low as 7 to 1, many times lower than the ratio of their mobilities, suggesting that few electrons are present in the near-extractor plasma. This, along with the near-equivalence of the positive and negative ion currents, suggests that the plasma in this region was mostly an ion-ion plasma. The negative chlorine current density was relatively insensitive to pressure, and scaled linearly with RF power. If this linear scaling continues to hold at higher RF powers, it should permit current densities of 100 45 mA/cm 2 , sufficient for present heavy ion fusion injector concepts. The effective ion temperatures of the positive and negative ions appeared to be similar and relatively low for a plasma source

Derivation of the threshold condition for the ion temperature gradient mode with an inverted density profile from a simple physics picture

Science.gov (United States)

Jhang, Hogun

2018-05-01

We show that the threshold condition for the toroidal ion temperature gradient (ITG) mode with an inverted density profile can be derived from a simple physics argument. The key in this picture is that the density inversion reduces the ion compression due to the ITG mode and the electron drift motion mitigates the poloidal potential build-up. This condition reproduces the same result that has been reported from a linear gyrokinetic calculation [T. S. Hahm and W. M. Tang, Phys. Fluids B 1, 1185 (1989)]. The destabilizing role of trapped electrons in toroidal geometry is easily captured in this picture.

High density nitrogen-vacancy sensing surface created via He{sup +} ion implantation of {sup 12}C diamond

Energy Technology Data Exchange (ETDEWEB)

Kleinsasser, Ed E., E-mail: edklein@uw.edu [Department of Electrical Engineering, University of Washington, Seattle, Washington 98195-2500 (United States); Stanfield, Matthew M.; Banks, Jannel K. Q. [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Zhu, Zhouyang; Li, Wen-Di [HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), Shenzhen 518000 (China); Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong (China); Acosta, Victor M. [Department of Physics and Astronomy, Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87106 (United States); Watanabe, Hideyuki [Correlated Electronics Group, Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8565 (Japan); Itoh, Kohei M. [School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Fu, Kai-Mei C., E-mail: kaimeifu@uw.edu [Department of Electrical Engineering, University of Washington, Seattle, Washington 98195-2500 (United States); Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States)

2016-05-16

We present a promising method for creating high-density ensembles of nitrogen-vacancy centers with narrow spin-resonances for high-sensitivity magnetic imaging. Practically, narrow spin-resonance linewidths substantially reduce the optical and RF power requirements for ensemble-based sensing. The method combines isotope purified diamond growth, in situ nitrogen doping, and helium ion implantation to realize a 100 nm-thick sensing surface. The obtained 10{sup 17 }cm{sup −3} nitrogen-vacancy density is only a factor of 10 less than the highest densities reported to date, with an observed 200 kHz spin resonance linewidth over 10 times narrower.

Formation time of hadrons and density of matter produced in relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Pisut, J.; Zavada, P.

1994-06-01

Densities of interacting hadronic matter produced in Oxygen-Lead and Sulphur-Lead collisions at 200 GeV/nucleon are estimated as a function of the formation time of hadrons. Uncertainties in our knowledge of the critical temperature T c and of the formation time of hadrons τ 0 permit at present three scenarios: an optimistic one (QGP has already been produced in collisions of Oxygen and Sulphur with heavy ions and will be copiously in Lead collisions), a pessimistic one (QGP cannot be produced at 200 GeV/nucleon) and an intermediate one (QGP has not been produced in Oxygen and Sulphur Interactions with heavy ions and will be at best produced only marginally in Pb-collisions). The last option is found to be the most probable. (author)

Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

Science.gov (United States)

Li, Wangda; Dolocan, Andrei; Oh, Pilgun; Celio, Hugo; Park, Suhyeon; Cho, Jaephil; Manthiram, Arumugam

2017-01-01

Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species. By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries. PMID:28443608

Ion Channel Trafficking: Control of Ion Channel Density as a Target for Arrhythmias?

Directory of Open Access Journals (Sweden)

Elise Balse

2017-10-01

Full Text Available The shape of the cardiac action potential (AP is determined by the contributions of numerous ion channels. Any dysfunction in the proper function or expression of these ion channels can result in a change in effective refractory period (ERP and lead to arrhythmia. The processes underlying the correct targeting of ion channels to the plasma membrane are complex, and have not been fully characterized in cardiac myocytes. Emerging evidence highlights ion channel trafficking as a potential causative factor in certain acquired and inherited arrhythmias, and therapies which target trafficking as opposed to pore block are starting to receive attention. In this review we present the current evidence for the mechanisms which underlie precise control of cardiac ion channel trafficking and targeting.

Mesospheric H2O and H2O2 densities inferred from in situ positive ion composition measurement

Science.gov (United States)

Kopp, E.

1984-01-01

A model for production and loss of oxonium ions in the high-latitude D-region is developed, based on the observed excess of 34(+) which has been interpreted as H2O2(+). The loss mechanism suggested in the study is the attachment of N2 and/or CO2 in three-body reactions. Furthermore, mesospheric water vapor and H2O2 densities are inferred from measurements of four high-latitude ion compositions, based on the oxonium model. Mixing ratios of hydrogen peroxide of up to two orders of magnitude higher than previous values were obtained. A number of reactions, reaction constants, and a block diagram of the oxonium ion chemistry in the D-region are given.

Phase-space densities and effects of resonance decays in a hydrodynamic approach to heavy ion collisions

International Nuclear Information System (INIS)

Akkelin, S.V.; Sinyukov, Yu.M.

2004-01-01

A method allowing analysis of the overpopulation of phase space in heavy ion collisions in a model-independent way is proposed within the hydrodynamic approach. It makes it possible to extract a chemical potential of thermal pions at freeze-out, irrespective of the form of freeze-out (isothermal) hypersurface in Minkowski space and transverse flows on it. The contributions of resonance (with masses up to 2 GeV) decays to spectra, interferometry volumes, and phase-space densities are calculated and discussed in detail. The estimates of average phase-space densities and chemical potentials of thermal pions are obtained for SPS and RHIC energies. They demonstrate that multibosonic phenomena at those energies might be considered as a correction factor rather than as a significant physical effect. The analysis of the evolution of the pion average phase-space density in chemically frozen hadron systems shows that it is almost constant or slightly increases with time while the particle density and phase-space density at each space point decreases rapidly during the system's expansion. We found that, unlike the particle density, the average phase-space density has no direct link to the freeze-out criterion and final thermodynamic parameters, being connected rather to the initial phase-space density of hadronic matter formed in relativistic nucleus-nucleus collisions

Dispersion relations of density fluctuations observed by heavy ion beam probe in the TEXT tokamak

International Nuclear Information System (INIS)

Ross, D.W.

1990-09-01

Wave numbers as functions of frequency for density fluctuations in the core of the TEXT tokamak are measured in Heavy Ion Beam Probe experiments by analyzing the relative phases of signals originating from nearby points in the plasma. The adjacent points are typically 2 cm apart, with their relative orientation (δr, δθ) depending on position (r,θ). for angular frequencies ω ≤ 10 6 /s the signals are quite coherent, leading to reasonably well-defined ''dispersion relations.'' These do not correspond to known modes of the drift wave type, i.e., ballooning or slab-like electron drift waves or ion temperature gradient modes. The effect of finite sample volume size does not significantly alter this conclusion. 25 refs., 6 figs., 3 tabs

High Energy Density Li-ion Cells for EV’s Based on Novel, High Voltage Cathode Material Systems

Energy Technology Data Exchange (ETDEWEB)

Kepler, Keith [Farasis Energy Inc; Slater, Michael [Farasis Energy Inc

2018-03-14

This Li-ion cell technology development project had three objectives: to develop advanced electrode materials and cell components to enable stable high-voltage operation; to design and demonstrate a Li-ion cell using these materials that meets the PHEV40 performance targets; and to design and demonstrate a Li-ion cell using these materials that meets the EV performance targets. The major challenge to creating stable high energy cells with long cycle life is system integration. Although materials that can give high energy cells are known, stabilizing them towards long-term cycling in the presence of other novel cell components is a major challenge. The major technical barriers addressed by this work include low cathode specific energy, poor electrolyte stability during high voltage operation, and insufficient capacity retention during deep discharge for Si-containing anodes. Through the course of this project, Farasis was able to improve capacity retention of NCM materials for 4.4+ V operation, through both surface treatment and bulk-doping approaches. Other material advances include increased rate capability and of HE-NCM materials through novel synthesis approach, doubling the relative capacity at 1C over materials synthesized using standard methods. Silicon active materials proved challenging throughout the project and ultimately were the limiting factor in the energy density vs. cycle life trade off. By avoiding silicon anodes for the lower energy PHEV design, we manufactured cells with intermediate energy density and long cycle life under high voltage operation for PHEV applications. Cells with high energy density for EV applications were manufactured targeting a 300 Wh/kg design and were able to achieve > 200 cycles.

High energy density physics studies at the facility for antiprotons and ion research: the HEDgeHOB collaboration

International Nuclear Information System (INIS)

Tahir, N.A.; Stoehlker, T.; Geissel, H.; Shutov, A.; Lomonosov, I.V.; Fortov, V.E.; Piriz, A.R.; Redmer, R.; Deutsch, C.

2011-01-01

The forthcoming Facility for Antiprotons and Ion Research (FAIR) at Darmstadt, is going to be a unique accelerator facility that will deliver high quality, strongly bunched, well focused, intense beams of heavy ions that will lead to unprecedented specific power deposition in solid matter. This will generate macroscopic samples of High Energy Density (HED) matter with fairly uniform physical conditions. These samples can be used to study the thermophysical and transport properties of HED matter. Extensive theoretical work has been carried out over the past decade to design numerous dedicated experiments to study HED physics at the FAIR, which has provided the basis for the HEDgeHOB (High Energy Density Matter Generated by Heavy Ion Beams) scientific proposal. This work is still in progress as the feasibility studies for more experimental schemes are being carried out. Another, very important research area that will benefit tremendously from the FAIR facility, is the production of radioactive beams. A superconducting fragment separator, Super-FRS is being designed for the production and separation of rare radioactive isotopes. Unlike the HED targets, the Super-FRS production target should not be destroyed or damaged by the beam, but should remain intact during the long experimental campaign. However, the high level of specific power deposited in the production target by the high intensity ion beam at FAIR, could cause serious problems to the target survival. These HED issues related to the Super-FRS production target are also discussed in the present paper (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Interaction of energetic ions with high-density plasmas

International Nuclear Information System (INIS)

Gericke, D.O.; Edie, D.; Grinenko, A.; Vorberger, J.

2010-01-01

Complete text of publication follows. The talk will review the importance of energetic ions in different inertial confinement fusion scenarios: i) heavy ion beams are very efficient drivers that can deliver the energy for compression in indirect as well as direct drive approaches; ii) the interaction of α-particles, that are created in a burning plasma, with the surrounding cold plasma is essential for creating a burn wave; iii) laser-produced ion beams are also a strong candidate to create the hot spot needed for fast ignition. In all applications the ions interact with dense matter that is characterized by strongly coupled ions and (possibly) partially degenerate electrons. Moreover, the coupling between beam ions and target electrons can be strong as well. Under these conditions, standard approaches for the beam-plasma interactions process are known to fail. The presentation will demonstrate how advanced models for the energy loss of ions in dense plasmas can resolve the issues mentioned above. These models are largely built on quantum kinetic theory that is able to describe degeneracy and strong coupling in a systematic way. In particular, strong interactions require a quantum description for electron-ion collisions in dense plasma environments, which is done by direct solutions of the Schroedinger equation. Degeneracy and collective excitations can be included via the Lenard-Balescu description where strong interactions may be included via a pseudo-potential approach. Finally, results are shown for all three fusion applications described above. The effects related to strong coupling and degeneracy mainly concern the end of the stopping range where the beam ion dose not have enough energy to excite all possible degrees of freedom and, thus, certain processes are frozen out. However, we also find a significant reduction of the range for swift heavy ions in the GeV-range when stopping in dense matter is considered. The stopping range of α-particles in the

Brightness enhancement of plasma ion source by utilizing anode spot for nano applications

Energy Technology Data Exchange (ETDEWEB)

Park, Yeong-Shin; Lee, Yuna; Chung, Kyoung-Jae; Hwang, Y. S. [Department of Nuclear Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, Yoon-Jae [Samsung Electronics Co. Ltd., Gyeonggi 445-701 (Korea, Republic of); Park, Man-Jin [Research Institute of Nano Manufacturing System, Seoul National University of Science and Technology, Seoul 139-743 (Korea, Republic of); Moon, Dae Won [Nanobio Fusion Research Center, Korea Research Institute of Standards and Science, Daejeon 305-600 (Korea, Republic of)

2012-02-15

Anode spots are known as additional discharges on positively biased electrode immersed in plasmas. The anode spot plasma ion source (ASPIS) has been investigated as a high brightness ion source for nano applications such as focused ion beam (FIB) and nano medium energy ion scattering (nano-MEIS). The generation of anode spot is found to enhance brightness of ion beam since the anode spot increases plasma density near the extraction aperture. Brightness of the ASPIS has been estimated from measurement of emittance for total ion beam extracted through sub-mm aperture. The ASPIS is installed to the FIB system. Currents and diameters of the focused beams with/without anode spot are measured and compared. As the anode spot is turned on, the enhancement of beam current is observed at fixed diameter of the focused ion beam. Consequently, the brightness of the focused ion beam is enhanced as well. For argon ion beam, the maximum normalized brightness of 12 300 A/m{sup 2} SrV is acquired. The ASPIS is applied to nano-MEIS as well. The ASPIS is found to increase the beam current density and the power efficiency of the ion source for nano-MEIS. From the present study, it is shown that the ASPIS can enhance the performance of devices for nano applications.

Heating tokamaks via the ion-cyclotron and ion-ion hybrid resonances

International Nuclear Information System (INIS)

Perkins, F.W.

1977-04-01

For the ion-ion hybrid resonance it is shown that: (1) the energy absorption occurs via a sequence of mode conversions; (2) a poloidal field component normal to the ion-ion hybrid mode conversion surface strongly influences the mode conversion process so that roughly equal electron and ion heating occurs in the present proton-deuterium experiments, while solely electron heating is predicted to prevail in deuterium-tritium reactors; (3) the ion-ion hybrid resonance suppresses toroidal eigenmodes; and (4) wave absorption in minority fundamental ion-cyclotron heating experiments will be dominated by ion-ion hybrid mode conversion absorption for minority concentrations exceeding roughly 1 percent. For the ion-cyclotron resonance, it is shown that: (1) ion-cyclotron mode conversion leads to surface electron heating; and (2) ion-cyclotron mode conversion absorption dominates fundamental ion-cyclotron absorption thereby preventing efficient ion heating

Ion distributions, exclusion coefficients, and separation factors of electrolytes in a charged cylindrical nanopore: a partially perturbative density functional theory study.

Science.gov (United States)

Peng, Bo; Yu, Yang-Xin

2009-10-07

The structural and thermodynamic properties for charge symmetric and asymmetric electrolytes as well as mixed electrolyte system inside a charged cylindrical nanopore are investigated using a partially perturbative density functional theory. The electrolytes are treated in the restricted primitive model and the internal surface of the cylindrical nanopore is considered to have a uniform charge density. The proposed theory is directly applicable to the arbitrary mixed electrolyte solution containing ions with the equal diameter and different valences. Large amount of simulation data for ion density distributions, separation factors, and exclusion coefficients are used to determine the range of validity of the partially perturbative density functional theory for monovalent and multivalent counterion systems. The proposed theory is found to be in good agreement with the simulations for both mono- and multivalent counterion systems. In contrast, the classical Poisson-Boltzmann equation only provides reasonable descriptions of monovalent counterion system at low bulk density, and is qualitatively and quantitatively wrong in the prediction for the multivalent counterion systems due to its neglect of the strong interionic correlations in these systems. The proposed density functional theory has also been applied to an electrolyte absorbed into a pore that is a model of the filter of a physiological calcium channel.

Total binding energy of heavy positive ions including density treatment of Darwin and Breit corrections

International Nuclear Information System (INIS)

Hill, S.H.; Grout, P.J.; March, N.H.

1987-01-01

Previous work on the relativistic Thomas-Fermi treatment of total energies of neutral atoms is first generalised to heavy positive ions. To facilitate quantitative contact with the numerical predictions of Dirac-Fock theory, Darwin and Breit corrections are expressed in terms of electron density, and computed using input again from relativistic Thomas-Fermi theory. These corrections significantly improve the agreement between the two seemingly very different theories. (author)

Inferring Magnetospheric Heavy Ion Density using EMIC Waves

Energy Technology Data Exchange (ETDEWEB)

Kim, Eun-Hwa; Johnson, Jay R.; Kim, Hyomin; Lee, Dong-Hun

2014-05-01

We present a method to infer heavy ion concentration ratios from EMIC wave observations that result from ionion hybrid (IIH) resonance. A key feature of the ion-ion hybrid resonance is the concentration of wave energy in a field-aligned resonant mode that exhibits linear polarization. This mode converted wave is localized at the location where the frequency of a compressional wave driver matches the IIH resonance condition, which depends sensitively on the heavy ion concentration. This dependence makes it possible to estimate the heavy ion concentration ratio. In this letter, we evaluate the absorption coefficients at the IIH resonance at Earth's geosynchronous orbit for variable concentrations of He+ and field-aligned wave numbers using a dipole magnetic field. Although wave absorption occurs for a wide range of heavy ion concentrations, it only occurs for a limited range of field-aligned wave numbers such that the IIH resonance frequency is close to, but not exactly the same as the crossover frequency. Using the wave absorption and observed EMIC waves from GOES-12 satellite, we demonstrate how this technique can be used to estimate that the He+ concentration is around 4% near L = 6.6.

Stability of Non-Neutral Plasma Cylinder Consisting of Magnetized Cold Electrons and of Small Density Fraction of Ions Born at Rest: Non-Local Analysis

Science.gov (United States)

Yeliseyev, Y. N.

2009-03-01

The non-local stability problem of the plasma cylinder, filled with "cold" magnetized rigidly rotating electrons, and a small density fraction of ions, is solved. The ions are supposed to be born at rest by ionization of background gas. The study is based on the kinetic description of ions. The equilibrium distribution function, taking into account the peculiarity of ions birth, is used. The radial electric field is caused by space charge of non-neutral plasma. The dispersion equation for plasma eigen frequencies is obtained analytically. It is valid within the total admissible range of values of electric and magnetic fields. Normalized eigen frequencies ω'/Ωi are calculated for the basic azimuth mode m = 1 (ω' = ω-mωi+, ω+ = (-ωci+Ωi)/2, Ωi = (ωci2-4eEr/mir)1/2 is called the "modified" ion cyclotron (MIC) frequency), for the density fraction of ions of atomic nitrogen f = Ni/ne = 0,01 and are presented in graphic form versus parameter 2ωpe2/ωce2. The spectra of oscillations ω'/Ωi consist of the family of electron Trivel-piece—Gould (TG) modes and of the families of MIC modes. The frequencies of MIC modes are located in a small vicinity of harmonics of the MIC frequency Ωi above and below the harmonic. The TG modes in non-neutral plasma fall in the region of MIC frequencies Ωi and interact strongly with MIC modes. The slow TG modes become unstable near the crossings with non-negative harmonics of MIC frequencies. The instabilities have a resonant character. The lowest radial TG mode has a maximum growth rate at crossing with a zero harmonic of Ωi ((Im ω'/Ωi)max≈0,074). The growth rates of MIC modes are much lower ((Im ω'/Ωi)max≲0,002). Their instability has a threshold character. The instabilities of TG and MIC modes take place mainly at the values of parameter 2ωpe2/ωce2, corresponding to strong radial electric fields (ωci2≪|eEr/mir|), in which the ions are unmagnetized. The oscillations of small amplitude are seen on some frequency

Investigation of reordered (001) Au surfaces by positive ion channeling spectroscopy, LEED and AES

International Nuclear Information System (INIS)

Appleton, B.R.; Noggle, T.S.; Miller, J.W.; Schow, O.E. III; Zehner, D.M.; Jenkins, L.H.; Barrett, J.H.

1974-01-01

As a consequence of the channeling phenomenon of positive ions in single crystals, the yield of ions Rutherford scattered from an oriented single crystal surface is dependent on the density of surface atoms exposed to the incident ion beam. Thus, the positive ion channeling spectroscopy (PICS) technique should provide a useful tool for studying reordered surfaces. This possibility was explored by examining the surfaces of epitaxially grown thin Au single crystals with the combined techniques of LEED-AES and PICS. The LEED and AES investigations showed that when the (001) surface was sputter cleaned in ultra-high vacuum, the normal (1 x 1) symmetry of the (001) surfaces reordered into a structure which gave a complex (5 x 20) LEED pattern. The yield and energy distributions of 1 MeV He ions scattered from the Au surfaces were used to determine the number of effective monolayers contributing to the normal and reordered surfaces. These combined measurements were used to characterize the nature of the reordered surface. The general applicability of the PICS technique for investigations of surface and near surface regions is discussed

Effect of 520 MeV Kr{sup 20+} ion irradiation on the critical current density of Bi-2212 single crystals

Energy Technology Data Exchange (ETDEWEB)

Terai, Takayuki; Ito, Yasuyuki [Tokyo Univ. (Japan). Faculty of Engineering; Kishio, Kouji

1996-10-01

Change in magnetic properties of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+y} (Bi-2212) single crystals due to Kr{sup 20+} ion irradiation is reported, focused on critical current density and irreversibility magnetic field. The Bi-2212 single crystal specimens (3x3x0.3 mm{sup 3}) were prepared by the floating zone method. Each specimen was irradiated with 520 MeV Kr{sup 20+} ions of 10{sup 10}-10{sup 11} cm{sup -2} in the fluence. Magnetic hysteresis was measured at 4.2K-60K with a vibrating sample magnetometer before and after irradiation. Very large enhancement was observed in critical current density and irreversibility magnetic field above 20K. (author)

Duopigatron ion source studies

International Nuclear Information System (INIS)

Bacon, F.M.; Bickes, R.W. Jr.; O'Hagan, J.B.

1978-07-01

Ion source performance characteristics consisting of total ion current, ion energy distribution, mass distribution, and ion current density distribution were measured for several models of a duopigatron. Variations on the duopigatron design involved plasma expansion cup material and dimensions, secondary cathode material, and interelectrode spacings. Of the designs tested, the one with a copper and molybdenum secondary cathode and a mild steel plasma expansion cup proved to give the best results. The ion current density distribution was peaked at the center of the plasma expansion cup and fell off to 80 percent of the peak value at the cup wall for a cup 15.2 mm deep. A total ion current of 180 mA consisting of 60 to 70 percent atomic ions was produced with an arc current of 20 A and source pressure of 9.3 Pa. More shallow cups produced a larger beam current and a more sharply peaked ion current density distribution. Typical ion energy distributions were bell-shaped curves with a peak 10 to 20 V below anode potential and with ion energies extending 30 to 40 V on either side of the peak

Optimum electron temperature and density for short-wavelength plasma-lasing from nickel-like ions

International Nuclear Information System (INIS)

Masoudnia, Leili; Bleiner, Davide

2014-01-01

Soft X-ray lasing across a Ni-like plasma gain-medium requires optimum electron temperature and density for attaining to the Ni-like ion stage and for population inversion in the 3d 9 4d 1 (J=0)→3d 9 4p 1 (J=1) laser transition. Various scaling laws, function of operating parameters, were compared with respect to their predictions for optimum temperatures and densities. It is shown that the widely adopted local thermodynamic equilibrium (LTE) model underestimates the optimum plasma-lasing conditions. On the other hand, non-LTE models, especially when complemented with dielectronic recombination, provided accurate prediction of the optimum plasma-lasing conditions. It is further shown that, for targets with Z equal or greater than the rare-earth elements (e.g. Sm), the optimum electron density for plasma-lasing is not accessible for pump-pulses at λ=1ω=1μm. This observation explains a fundamental difficulty in saturating the wavelength of plasma-based X-ray lasers below 6.8 nm, unless using 2ω pumping

Dependence of the bystander effect for micronucleus formation on dose of heavy-ion radiation in normal human fibroblasts

International Nuclear Information System (INIS)

Matsumoto, Yoshitaka; Hamada, Nobuyuki; Aoki-Nakano, Mizuho; Furusawa, Yoshiya; Funayama, Tomoo; Sakashita, Tetsuya; Kobayashi, Yasuhiko; Wada, Seiichi; Kakizaki, Takehiko

2015-01-01

Ionising radiation-induced bystander effects are well recognised, but its dependence on dose or linear energy transfer (LET) is still a matter of debate. To test this, 49 sites in confluent cultures of AG01522D normal human fibroblasts were targeted with microbeams of carbon (103 keV μm -1 ), neon (375 keV μm -1 ) and argon ions (1260 keV μm -1 ) and evaluated for the bystander-induced formation of micronucleus that is a kind of a chromosome aberration. Targeted exposure to neon and argon ions significantly increased the micronucleus frequency in bystander cells to the similar extent irrespective of the particle numbers per site of 1- 6. In contrast, the bystander micronucleus frequency increased with increasing the number of carbon-ion particles in a range between 1 and 3 particles per site and was similar in a range between 3 and 8 particles per site. These results suggest that the bystander effect of heavy ions for micronucleus formation depends on dose. (authors)

Identification of Raman peaks of high-Tc cuprates in normal state through density of states

International Nuclear Information System (INIS)

Bishoyi, K.C.; Rout, G.C.; Behera, S.N.

2007-01-01

We present a microscopic theory to explain and identify the Raman spectral peaks of high-T c cuprates R 2-x M x CuO 4 in the normal state. We used electronic Hamiltonian prescribed by Fulde in presence of anti-ferromagnetism. Phonon interaction to the hybridization between the conduction electrons of the system and the f-electrons has been incorporated in the calculation. The phonon spectral density is calculated by the Green's function technique of Zubarev at zero wave vector and finite (room) temperature limit. The four Raman active peaks (P 1 -P 4 ) representing the electronic states of the atomic sub-systems of the cuprate system are identified by the calculated quasi-particle energy bands and electron density of states (DOS). The effect of interactions on these peaks are also explained

Measurements of beam current density and proton fraction of a permanent-magnet microwave ion source

Energy Technology Data Exchange (ETDEWEB)

Waldmann, Ole; Ludewigt, Bernhard [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

2011-11-15

A permanent-magnet microwave ion source has been built for use in a high-yield, compact neutron generator. The source has been designed to produce up to 100 mA of deuterium and tritium ions. The electron-cyclotron resonance condition is met at a microwave frequency of 2.45 GHz and a magnetic field strength of 87.5 mT. The source operates at a low hydrogen gas pressure of about 0.15 Pa. Hydrogen beams with a current density of 40 mA/cm{sup 2} have been extracted at a microwave power of 450 W. The dependence of the extracted proton beam fraction on wall materials and operating parameters was measured and found to vary from 45% for steel to 95% for boron nitride as a wall liner material.

Ion thruster performance model

International Nuclear Information System (INIS)

Brophy, J.R.

1984-01-01

A model of ion thruster performance is developed for high flux density cusped magnetic field thruster designs. This model is formulated in terms of the average energy required to produce an ion in the discharge chamber plasma and the fraction of these ions that are extracted to form the beam. The direct loss of high energy (primary) electrons from the plasma to the anode is shown to have a major effect on thruster performance. The model provides simple algebraic equations enabling one to calculate the beam ion energy cost, the average discharge chamber plasma ion energy cost, the primary electron density, the primary-to-Maxwellian electron density ratio and the Maxwellian electron temperature. Experiments indicate that the model correctly predicts the variation in plasma ion energy cost for changes in propellant gas (Ar, Kr, and Xe), grid transparency to neutral atoms, beam extraction area, discharge voltage, and discharge chamber wall temperature

Low Bone Density

Science.gov (United States)

... Density Exam/Testing › Low Bone Density Low Bone Density Low bone density is when your bone density ... people with normal bone density. Detecting Low Bone Density A bone density test will determine whether you ...

Swift heavy ion induced single event upsets in high density UV-EPROM's

Energy Technology Data Exchange (ETDEWEB)

Dahiwale, S.S. [Department of Physics, University of Pune, Pune 7 (India); Shinde, N.S. [Department of Chemical Engineering, Mie University (Japan); Kanjilal, D. [Inter University Accelerator Center, New Delhi (India); Bhoraskar, V.N. [Department of Physics, University of Pune, Pune 7 (India); Dhole, S.D. [Department of Physics, University of Pune, Pune 7 (India)], E-mail: sanjay@physics.unipune.ernet.in

2008-04-15

A few high density UV-EPROM's (32Kb x 8) were irradiated with 5.41 MeV energy {alpha}-particles with fluences from 10{sup 4} to 10{sup 8} alphas/cm{sup 2} and 100 MeV nickel, iodine and silver ions for low fluences between 5 x 10{sup 7} and 10{sup 8} ions/cm{sup 2}. The energy and ion species was selected on the basis of predicted threshold values of linear energy transfer (LET) in silicon. The program which was stored in the memory found to be changed from 0 to 1 and 1 to 0 state, respectively. On the basis of changed states, the cross-sections ({sigma}) were calculated to investigate the single event effects/upsets. No upset was observed in case of {alpha}-particle since it has very low LET, but the SEU cross-section found to be more in case of Iodine i.e. 2.29 x 10{sup -3} cm{sup 2} than that of nickel, 2.12 x 10{sup -3} cm{sup 2} and silver, 2.26 x 10{sup -3}. This mainly attributes that LET for iodine is more as compared to silver and nickel ions, which deposits large amount of energy near the sensitive node of memory cell in the form of electron-hole pairs required to change the state. These measured SEU cross-section were also compared with theoretically predicted values along with the Weibull distribution fit to the ion induced experimental SEU data. The theoretical predicted SEU cross-section 3.27 x 10{sup -3} cm{sup 2} found to be in good agreement with the measured SEU cross-section.

Synthesis of Three-Dimensional Nanoporous Li-Rich Layered Cathode Oxides for High Volumetric and Power Energy Density Lithium-Ion Batteries.

Science.gov (United States)

Qiu, Bao; Yin, Chong; Xia, Yonggao; Liu, Zhaoping

2017-02-01

As rechargeable Li-ion batteries have expanded their applications into on-board energy storage for electric vehicles, the energy and power must be increased to meet the new demands. Li-rich layered oxides are one of the most promising candidate materials; however, it is very difficult to make them compatible with high volumetric energy density and power density. Here, we develop an innovative approach to synthesize three-dimensional (3D) nanoporous Li-rich layered oxides Li[Li 0.144 Ni 0.136 Co 0.136 Mn 0.544 ]O 2 , directly occurring at deep chemical delithiation with carbon dioxide. It is found that the as-prepared material presents a micrometer-sized spherical structure that is typically composed of interconnected nanosized subunits with narrow distributed pores at 3.6 nm. As a result, this unique 3D micro-/nanostructure not only has a high tap density over 2.20 g cm -3 but also exhibits excellent rate capability (197.6 mA h g -1 at 1250 mA g -1 ) as an electrode. The excellent electrochemical performance is ascribed to the unique nanoporous micro-nanostructures, which facilitates the Li + diffusion and enhances the structural stability of the Li-rich layered cathode materials. Our work offers a comprehensive designing strategy to construct 3D nanoporous Li-rich layered oxides for both high volumetric energy density and power density in Li-ion batteries.

Heavy-ion radiography and heavy-ion computed tomography

International Nuclear Information System (INIS)

Fabrikant, J.I.; Holley, W.R.; McFarland, E.W.; Tobias, C.a.

1982-02-01

Heavy-ion projection and CT radiography is being developed into a safe, low-dose, noninvasive radiological procedure that can quantitate and image small density differences in human tissues. The applications to heavy-ion mammography and heavy-ion CT imaging of the brain in clinical patients suggest their potential value in cancer diagnosis

Studies on Impingement Effects of Low Density Jets on Surfaces — Determination of Shear Stress and Normal Pressure

Science.gov (United States)

Sathian, Sarith. P.; Kurian, Job

2005-05-01

This paper presents the results of the Laser Reflection Method (LRM) for the determination of shear stress due to impingement of low-density free jets on flat plate. For thin oil film moving under the action of aerodynamic boundary layer the shear stress at the air-oil interface is equal to the shear stress between the surface and air. A direct and dynamic measurement of the oil film slope is measured using a position sensing detector (PSD). The thinning rate of oil film is directly measured which is the major advantage of the LRM over LISF method. From the oil film slope history, direct calculation of the shear stress is done using a three-point formula. For the full range of experiment conditions Knudsen numbers varied till the continuum limit of the transition regime. The shear stress values for low-density flows in the transition regime are thus obtained using LRM and the measured values of shear show fair agreement with those obtained by other methods. Results of the normal pressure measurements on a flat plate in low-density jets by using thermistors as pressure sensors are also presented in the paper. The normal pressure profiles obtained show the characteristic features of Newtonian impact theory for hypersonic flows.

Collective Focusing of Intense Ion Beam Pulses for High-energy Density Physics Applications

International Nuclear Information System (INIS)

Dorf, Mikhail A.; Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.

2011-01-01

The collective focusing concept in which a weak magnetic lens provides strong focusing of an intense ion beam pulse carrying a neutralizing electron background is investigated by making use of advanced particle-in-cell simulations and reduced analytical models. The original analysis by Robertson Phys. Rev. Lett. 48, 149 (1982) is extended to the parameter regimes of particular importance for several high-energy density physics applications. The present paper investigates (1) the effects of non-neutral collective focusing in a moderately strong magnetic field; (2) the diamagnetic effects leading to suppression of the applied magnetic field due to the presence of the beam pulse; and (3) the influence of a finite-radius conducting wall surrounding the beam cross-section on beam neutralization. In addition, it is demonstrated that the use of the collective focusing lens can significantly simplify the technical realization of the final focusing of ion beam pulses in the Neutralized Drift Compression Experiment-I (NDCX-I), and the conceptual designs of possible experiments on NDCX-I are investigated by making use of advanced numerical simulations.

Optimal pulse modulator design criteria for plasma source ion implanters

International Nuclear Information System (INIS)

Reass, W.

1993-01-01

This paper describes what are believed to be the required characteristics of a high-voltage modulator for efficient and optimal ion deposition from the ''Plasma Source Ion Implantation'' (PSII) process. The PSII process is a method to chemically or physically alter and enhance surface properties of objects by placing them in a weakly ionized plasma and pulsing the object with a high negative voltage. The attracted ions implant themselves and form chemical bonds or are interstitially mixed with the base material. Present industrial uses of implanted objects tends to be for limited-production, high-value-added items. Traditional implanting hardware uses the typical low-current (ma) semiconductor ''raster scan'' implanters. The targets must also be manipulated to maintain a surface normal to the ion beam. The PSII method can provide ''bulk'' equipment processing on a large industrial scale. For the first generation equipment, currents are scaled from milliamps to hundreds of amps, voltages to -175kV, at kilohertz rep-rates, and high plasma ion densities

POLYMERS CONTAINING Cu NANOPARTICLES IRRADIATED BY LASER TO ENHANCE THE ION ACCELERATION

Directory of Open Access Journals (Sweden)

Mariapompea Cutroneo

2015-06-01

Full Text Available Target Normal Sheath Acceleration method was employed at PALS to accelerate ions from laser-generated plasma at intensities above 1015 W/cm2. Laser parameters, irradiation conditions and target geometry and composition control the plasma properties and the electric field driving the ion acceleration. Cu nanoparticles deposited on the polymer promote resonant absorption effects increasing the plasma electron density and enhancing the proton acceleration. Protons can be accelerated in forward direction at kinetic energies up to about 3.5 MeV. The optimal target thickness, the maximum acceleration energy and the angular distribution of emitted particles have been measured using ion collectors, X-ray CCD streak camera, SiC detectors and Thomson Parabola Spectrometer.

Compressive and rarefactive dust-ion-acoustic Gardner solitons in a multi-component dusty plasma

International Nuclear Information System (INIS)

Ema, S. A.; Ferdousi, M.; Mamun, A. A.

2015-01-01

The linear and nonlinear propagations of dust-ion-acoustic solitary waves (DIASWs) in a collisionless four-component unmagnetized dusty plasma system containing nonextensive electrons, inertial negative ions, Maxwellian positive ions, and negatively charged static dust grains have been investigated theoretically. The linear properties are analyzed by using the normal mode analysis and the reductive perturbation method is used to derive the nonlinear equations, namely, the Korteweg-de Vries (K-dV), the modified K-dV (mK-dV), and the Gardner equations. The basic features (viz., polarity, amplitude, width, etc.) of Gardner solitons (GS) are found to exist beyond the K-dV limit and these dust-ion-acoustic GS are qualitatively different from the K-dV and mK-dV solitons. It is observed that the basic features of DIASWs are affected by various plasma parameters (viz., electron nonextensivity, negative-to-positive ion number density ratio, electron-to-positive ion number density ratio, electron-to-positive ion temperature ratio, etc.) of the considered plasma system. The findings of our results obtained from this theoretical investigation may be useful in understanding the nonlinear structures and the characteristics of DIASWs propagating in both space and laboratory plasmas

Gas and metal ion sources

International Nuclear Information System (INIS)

Oaks, E.; Yushkov, G.

1996-01-01

The positive ion sources are now of interest owing to both their conventional use, e.g., as injectors in charged-particle accelerators and the promising capabilities of intense ion beams in the processes related to the action of ions on various solid surfaces. For industrial use, the sources of intense ion beams and their power supplies should meet the specific requirements as follows: They should be simple, technologically effective, reliable, and relatively low-cost. Since the scanning of an intense ion beam is a complicated problem, broad ion beams hold the greatest promise. For the best use of such beams it is desirable that the ion current density be uniformly distributed over the beam cross section. The ion beam current density should be high enough for the treatment process be accomplished for an acceptable time. Thus, the ion sources used for high-current, high-dose metallurgical implantation should provide for gaining an exposure dose of ∼ 10 17 cm -2 in some tens of minutes. So the average ion current density at the surface under treatment should be over 10 -5 A/cm 2 . The upper limit of the current density depends on the admissible heating of the surface under treatment. The accelerating voltage of an ion source is dictated by its specific use; it seems to lie in the range from ∼1 kV (for the ion source used for surface sputtering) to ∼100 kV and over (for the ion sources used for high-current, high-dose metallurgical implantation)

Epidermal growth factor receptor-induced activato protein 1 activity controls density-dependent growht inhibition in normal rat kidney fibroblasts.

NARCIS (Netherlands)

Hornberg, J.J.; Dekker, H.; Peters, P.H.J.; Langerak, P.; Westerhoff, H.V.; Lankelma, J.; Zoelen, E.J.J.

2006-01-01

Density-dependent growth inhibition secures tissue homeostasis. Dysfunction of the mechanisms, which regulate this type of growth control is a major cause of neoplasia. In confluent normal rat kidney (NRK) fibroblasts, epidermal growth factor (EGF) receptor levels decline, ultimately rendering these

Development of a center for light ion therapy and accurate tumor diagnostics at karolinska institutet and hospital

Science.gov (United States)

Brahme, Anders; Lind, Bengt K.

2002-04-01

Radiation therapy is today in a state of very rapid development with new intensity modulated treatment techniques continuously being developed. This has made intensity modulated electron and photon beams almost as powerful as conventional uniform beam proton therapy. To be able to cure also the most advanced hypoxic and radiation resistant tumors of complex local spread, intensity modulated light ion beams are really the ultimate tool and only slightly more expensive than proton therapy. The aim of the new center for ion therapy and tumor diagnostics in Stockholm is to develop radiobiologically optimized 3-dimensional pencil beam scanning techniques. Beside the "classical" approaches using low ionization density hydrogen ions (protons, but also deuterons and tritium nuclei) and high ionization density carbon ions, two new approaches will be developed. In the first one lithium or beryllium ions, that induce the least detrimental biological effect to normal tissues for a given biological effect in a small volume of the tumor, will be key particles. In the second approach, referred patients will be given a high-dose high-precision "boost" treatment with carbon or oxygen ions during one week preceding the final treatment with conventional radiations in the referring hospital. The rationale behind these approaches is to reduce the high ionization density dose to the normal tissue stroma inside the tumor and to ensure a microscopically uniform dose delivery. The principal idea of the center is to closely integrate ion therapy into the clinical routine and research of a large radiotherapy department. The light ion therapy center will therefore be combined with advanced tumor diagnostics including MR and PET-CT imaging to facilitate efficient high-precision high-dose boost treatment of remitted patients. The possibility to do 3D tumor diagnostics and 3D dose delivery verification with the same PET camera will be the ultimate step in high quality adaptive radiation therapy

Enhanced Scattering of Diffuse Ions on Front of the Earth's Quasi-Parallel Bow Shock: a Case Study

Science.gov (United States)

Kis, A.; Matsukiyo, S.; Otsuka, F.; Hada, T.; Lemperger, I.; Dandouras, I. S.; Barta, V.; Facsko, G. I.

2017-12-01

In the analysis we present a case study of three energetic upstream ion events at the Earth's quasi-parallel bow shock based on multi-spacecraft data recorded by Cluster. The CIS-HIA instrument onboard Cluster provides partial energetic ion densities in 4 energy channels between 10 and 32 keV.The difference of the partial ion densities recorded by the individual spacecraft at various distances from the bow shock surface makes possible the determination of the spatial gradient of energetic ions.Using the gradient values we determined the spatial profile of the energetic ion partial densities as a function of distance from the bow shock and we calculated the e-folding distance and the diffusion coefficient for each event and each ion energy range. Results show that in two cases the scattering of diffuse ions takes place in a normal way, as "by the book", and the e-folding distance and diffusion coefficient values are comparable with previous results. On the other hand, in the third case the e-folding distance and the diffusion coefficient values are significantly lower, which suggests that in this case the scattering process -and therefore the diffusive shock acceleration (DSA) mechanism also- is much more efficient. Our analysis provides an explanation for this "enhanced" scattering process recorded in the third case.

Effect of Porosity on the Thick Electrodes for High Energy Density Lithium Ion Batteries for Stationary Applications

Directory of Open Access Journals (Sweden)

Madhav Singh

2016-11-01

Full Text Available A series of 250–350 μ m-thick single-sided lithium ion cell graphite anodes and lithium nickel manganese cobalt oxide (NMC cathodes with constant area weight, but varying porosity were prepared. Over this wide thickness range, micron-sized carbon fibers were used to stabilize the electrode structure and to improve electrode kinetics. By choosing the proper porosities for the anode and cathode, kinetic limitations and aging losses during cell cycling could be minimized and energy density improved. The cell (C38%-A48% exhibits the highest energy density, 441 Wh/L at the C/10 rate, upon cycling at elevated temperature and different C-rates. The cell (C38%-A48% showed 9% higher gravimetric energy density at C/10 in comparison to the cell with as-coated electrodes.

Measurements of beam current density and proton fraction of a permanent-magnet microwave ion source.

Science.gov (United States)

Waldmann, Ole; Ludewigt, Bernhard

2011-11-01

A permanent-magnet microwave ion source has been built for use in a high-yield, compact neutron generator. The source has been designed to produce up to 100 mA of deuterium and tritium ions. The electron-cyclotron resonance condition is met at a microwave frequency of 2.45 GHz and a magnetic field strength of 87.5 mT. The source operates at a low hydrogen gas pressure of about 0.15 Pa. Hydrogen beams with a current density of 40 mA/cm(2) have been extracted at a microwave power of 450 W. The dependence of the extracted proton beam fraction on wall materials and operating parameters was measured and found to vary from 45% for steel to 95% for boron nitride as a wall liner material. © 2011 American Institute of Physics

Spatial distribution of ion energy related on electron density in a plasma channel generated in gas clusters by a femtosecond laser

International Nuclear Information System (INIS)

Nam, S. M.; Han, J. M.; Cha, Y. H.; Lee, Y. W.; Rhee, Y. J.; Cha, H. K.

2008-01-01

Neutron generation through Coulomb explosion of deuterium contained gas clusters is known as one of the very effective methods to produce fusion neutrons using a table top terawatt laser. The energy of ions produced through Coulomb explosions is very important factor to generate neutrons efficiently. Until the ion energy reaches around∼MeV level, the D D fusion reaction probability increases exponentially. The understanding of laser beam propagation and laser energy deposition in clusters is very important to improve neutron yields. As the laser beam propagates through clusters medium, laser energy is absorbed in clusters by ionization of molecules consisting clusters. When the backing pressure of gas increases, the average size of clusters increases and which results in higher energy absorption and earlier termination of laser propagation. We first installed a Michelson interferometer to view laser beam traces in a cluster plume and to measure spatial electron density profiles of a plasma channel which was produced by a laser beam. And then we measured the energy of ions distributed along the plasma channel with a translating slit to select ions from narrow parts of a plasma channel. In our experiments, methane gas was used to produce gas clusters at a room temperature and the energy distribution of proton ions for different gas backing pressure were measured by the time of flight method using dual micro channel plates. By comparing the distribution of ion energies and electron densities, we could understand the condition for effective laser energy delivery to clusters

Influence of ion pairing in ionic liquids on electrical double layer structures and surface force using classical density functional approach.

Science.gov (United States)

Ma, Ke; Forsman, Jan; Woodward, Clifford E

2015-05-07

We explore the influence of ion pairing in room temperature ionic liquids confined by planar electrode surfaces. Using a coarse-grained model for the aromatic ionic liquid [C4MIM(+)][BF4 (-)], we account for an ion pairing component as an equilibrium associating species within a classical density functional theory. We investigated the resulting structure of the electrical double layer as well as the ensuing surface forces and differential capacitance, as a function of the degree of ion association. We found that the short-range structure adjacent to surfaces was remarkably unaffected by the degree of ion pairing, up to several molecular diameters. This was even the case for 100% of ions being paired. The physical implications of ion pairing only become apparent in equilibrium properties that depend upon the long-range screening of charges, such as the asymptotic behaviour of surface forces and the differential capacitance, especially at low surface potential. The effect of ion pairing on capacitance is consistent with their invocation as a source of the anomalous temperature dependence of the latter. This work shows that ion pairing effects on equilibrium properties are subtle and may be difficult to extract directly from simulations.

Heavy ion physics at BNL, the AGS and RHIC

International Nuclear Information System (INIS)

Lowenstein, D.I.

1985-01-01

The advent of heavy ion acceleration with the AGS at Brookhaven National Laboratory in 1986 and the proposed Relativistic Heavy Ion Collider (RHIC) for 1990 brings us into a temperature and density regime well above anything yet produced and into a time domain of the early universe of 10 -13 -10 -6 seconds. The physics of high energy heavy ions range from the more traditional nuclear physics to the formation of new forms of matter. Quantum Chromodynamics (QCD) is the latest, and as of yet, the most successful theory to describe the interaction of quarks and gluons. The nature of the confinement of the quarks and gluons under extremes of temperature and density is one of the compelling reasons for this new physics program at BNL. There are reasons to believe that with collisions of heavy nuclei at energies in the 10 to 100 GeV/amu range a very large volume of approx. 10 fm 3 would be heated to 200-300 MeV and/or acquire a sufficient quark density (5-10 times normal baryon density) so that the entire contents of the volume would be deconfined and the quarks and gluons would form a plasma. The kinematic region for the extant machines and the proposed RHIC are shown. At AGS energies the baryons in colliding nuclei bring each other to rest, yielding fragmentation regions of high baryon density. These are the regions in which supernorvae and neutrons stars exist. For energies much higher, such as in RHIC, nuclei are transparent to each other and one can form a central region of almost zero baryon density, mostly pions, and very high temperature. This is the region of the early universe and the quark-gluon plasma. Design parameters and cost of the RHIC are discussed

Reflection of ion acoustic solitons in a plasma having negative ions

International Nuclear Information System (INIS)

Chauhan, S.S.; Malik, H.K.; Dahiya, R.P.

1996-01-01

Reflection of compressive and rarefactive ion acoustic solitons propagating in an inhomogeneous plasma in the presence of negative ions is investigated. Modified Korteweg endash deVries equations for incident and reflected solitons are derived and solved. The amplitude of incident and reflected solitons increases with negative to positive ion density ratio. With increasing density ratio, reflection of rarefactive solitons is reinforced whereas that of compressive solitons weakened. The rarefactive solitons are found to undergo stronger reflection than the compressive ones. copyright 1996 American Institute of Physics

Aerosol nucleation in an ultra-low ion density environment

DEFF Research Database (Denmark)

Pedersen, Jens Olaf Pepke; Enghoff, Martin Andreas Bødker; Paling, Sean M.

2012-01-01

Ion-induced nucleation has been studied in a deep underground ultra-low background radiation environment where the role of ions can be distinguished from alternative neutral aerosol nucleation mechanisms. Our results demonstrate that ions have a significant effect on the production of small...... sulfuric acid–water clusters over a range of sulfuric acid concentrations although neutral nucleation mechanisms remain evident at low ionization levels. The effect of ions is found both to enhance the nucleation rate of stable clusters and the initial growth rate. The effects of possible contaminations...

Density-dependent lines of one- and two-electron ions in diagnostics of laboratory plasma. I. The rates of collision relaxation of excited levels

Energy Technology Data Exchange (ETDEWEB)

Shevelko, V P; Skobelev, I Yu; Vinogradov, A V [Lebedev Physical Institute, Academy of Sciences of the USSR, Moscow, USSR

1977-01-01

Plasma devices with inertial plasma confinement such as laser produced plasmas, exploding wires, plasma focus, etc., which have been rapidly developed during recent years., appear to be very intensive sources of spectral line radiation in far UV and X-ray regions. Analysis of this radiation provides a good tool for plasma diagnostics with very high electron densities up to 10/sup 22/cm/sup -3/. In this work, consisting of two parts, the authors consider the mechanism of the formation of spectral lines in hot and dense plasma. The key point for density diagnostics is the fact that for some ion levels the rate of collisional relaxation has the same order of magnitude as the radiative decay. Thus the intensities of spectral lines arising from these levels show a strong dependence on electron density which makes diagnostics possible. In this paper, emphasis is laid on the calculation of rates of transition between close ion levels induced by electron or ion impact, which usually gives the main contribution to the collisional relaxation constants. The influence of plasma polarization effects on the collision frequency in a dense plasma is also considered.

Theoretical Probing of Weak Anion-Cation Interactions in Certain Pyridinium-Based Ionic Liquid Ion Pairs and the Application of Molecular Electrostatic Potential in Their Ionic Crystal Density Determination: A Comparative Study Using Density Functional Approach.

Science.gov (United States)

Joseph, Aswathy; Thomas, Vibin Ipe; Żyła, Gaweł; Padmanabhan, A S; Mathew, Suresh

2018-01-11

A comprehensive study on the structure, nature of interaction, and properties of six ionic pairs of 1-butylpyridinium and 1-butyl-4-methylpyridinium cations in combination with tetrafluoroborate (BF 4 - ), chloride (Cl - ), and bromide (Br - ) anions have been carried out using density functional theory (DFT). The anion-cation interaction energy (ΔE int ), thermochemistry values, theoretical band gap, molecular orbital energy order, DFT-based chemical activity descriptors [chemical potential (μ), chemical hardness (η), and electrophilicity index (ω)], and distribution of density of states (DOS) of these ion pairs were investigated. The ascendancy of the -CH 3 substituent at the fourth position of the 1-butylpyridinium cation ring on the values of ΔE int , theoretical band gap and chemical activity descriptors was evaluated. The ΔE int values were negative for all six ion pairs and were highest for Cl - containing ion pairs. The theoretical band gap value after -CH 3 substitution increased from 3.78 to 3.96 eV (for Cl - ) and from 2.74 to 2.88 eV (for Br - ) and decreased from 4.9 to 4.89 eV (for BF 4 - ). Ion pairs of BF 4 - were more susceptible to charge transfer processes as inferred from their significantly high η values and comparatively small difference in ω value after -CH 3 substitution. The change in η and μ values due to the -CH 3 substituent is negligibly small in all cases except for the ion pairs of Cl - . Critical-point (CP) analyses were carried out to investigate the AIM topological parameters at the interionic bond critical points (BCPs). The RDG isosurface analysis indicated that the anion-cation interaction was dominated by strong H cat ···X ani and C cat ···X ani interactions in ion pairs of Cl - and Br - whereas a weak van der Waal's effect dominated in ion pairs of BF 4 - . The molecular electrostatic potential (MESP)-based parameter ΔΔV min measuring the anion-cation interaction strength showed a good linear correlation with

Injection of auxiliary electrons for increasing the plasma density in highly charged and high intensity ion sources

Energy Technology Data Exchange (ETDEWEB)

Odorici, F., E-mail: fabrizio.odorici@bo.infn.it; Malferrari, L.; Montanari, A. [INFN—Bologna, Viale B. Pichat, 6/2, 40127 Bologna (Italy); Rizzoli, R. [INFN—Bologna, Viale B. Pichat, 6/2, 40127 Bologna (Italy); CNR–Istituto per la Microelettronica ed i Microsistemi, Via Gobetti 101, 40129 Bologna (Italy); Mascali, D.; Castro, G.; Celona, L.; Gammino, S.; Neri, L. [INFN–Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy)

2016-02-15

Different electron guns based on cold- or hot-cathode technologies have been developed since 2009 at INFN for operating within ECR plasma chambers as sources of auxiliary electrons, with the aim of boosting the source performances by means of a higher plasma lifetime and density. Their application to microwave discharge ion sources, where plasma is not confined, has required an improvement of the gun design, in order to “screen” the cathode from the plasma particles. Experimental tests carried out on a plasma reactor show a boost of the plasma density, ranging from 10% to 90% when the electron guns are used, as explained by plasma diffusion models.

Injection of auxiliary electrons for increasing the plasma density in highly charged and high intensity ion sources.

Science.gov (United States)

Odorici, F; Malferrari, L; Montanari, A; Rizzoli, R; Mascali, D; Castro, G; Celona, L; Gammino, S; Neri, L

2016-02-01

Different electron guns based on cold- or hot-cathode technologies have been developed since 2009 at INFN for operating within ECR plasma chambers as sources of auxiliary electrons, with the aim of boosting the source performances by means of a higher plasma lifetime and density. Their application to microwave discharge ion sources, where plasma is not confined, has required an improvement of the gun design, in order to "screen" the cathode from the plasma particles. Experimental tests carried out on a plasma reactor show a boost of the plasma density, ranging from 10% to 90% when the electron guns are used, as explained by plasma diffusion models.

Cellular and molecular effects for mutation induction in normal human cells irradiated with accelerated neon ions

International Nuclear Information System (INIS)

Suzuki, Masao; Tsuruoka, Chizuru; Kanai, Tatsuaki; Kato, Takeshi; Yatagai, Fumio; Watanabe, Masami

2006-01-01

We investigated the linear energy transfer (LET) dependence of mutation induction on the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus in normal human fibroblast-like cells irradiated with accelerated neon-ion beams. The cells were irradiated with neon-ion beams at various LETs ranging from 63 to 335 keV/μm. Neon-ion beams were accelerated by the Riken Ring Cyclotron at the Institute of Physical and Chemical Research in Japan. Mutation induction at the HPRT locus was detected to measure 6-thioguanine-resistant clones. The mutation spectrum of the deletion pattern of exons of mutants was analyzed using the multiplex polymerase chain reaction (PCR). The dose-response curves increased steeply up to 0.5 Gy and leveled off or decreased between 0.5 and 1.0 Gy, compared to the response to 137 Cs γ-rays. The mutation frequency increased up to 105 keV/μm and then there was a downward trend with increasing LET values. The deletion pattern of exons was non-specific. About 75-100% of the mutants produced using LETs ranging from 63 to 335 keV/μm showed all or partial deletions of exons, while among γ-ray-induced mutants 30% showed no deletions, 30% partial deletions and 40% complete deletions. These results suggested that the dose-response curves of neon-ion-induced mutations were dependent upon LET values, but the deletion pattern of DNA was not

Electron cyclotron resonance (E.C.R.) multiply charged ion sources

International Nuclear Information System (INIS)

Geller, R.

1978-01-01

High charge state ions can be produced by electron bombardment inside targets when the target electron density n (cm -3 ) multiplied by the ion transit time through the target tau (sec) is: n tau > 5.10 9 cm -3 sec. The relative velocity between electrons and ions determines the balance between stripping and capture i.e. the final ion charge state. (In a stripper foil fast ions interact with slow electrons involving typically n approximately 10 24 cm -3 , tau approximately 10 -14 sec). In the E.C.R. source a cold ion plasma created in a first stage diffuses slowly through a second stage containing a hot E.C.R. plasma with n > 3.10 11 cm -3 and tau > 10 -2 sec. Continuous beams of several μA of C 6+ N 7+ Ne 9+ A 11+ are extracted from the second stage with normalized emittances of approximately 0.5 π mm mrad. The absence of cathodes and plasma arcs makes the source very robust, reliable and well-fitted for cyclotron injection. A super conducting source is under development

Ion Acceleration by Double Layers with Multi-Component Ion Species

Science.gov (United States)

Good, Timothy; Aguirre, Evan; Scime, Earl; West Virginia University Team

2017-10-01

Current-free double layers (CFDL) models have been proposed to explain observations of magnetic field-aligned ion acceleration in plasmas expanding into divergent magnetic field regions. More recently, experimental studies of the Bohm sheath criterion in multiple ion species plasma reveal an equilibration of Bohm speeds at the sheath-presheath boundary for a grounded plate in a multipole-confined filament discharge. We aim to test this ion velocity effect for CFDL acceleration. We report high resolution ion velocity distribution function (IVDF) measurements using laser induced fluorescence downstream of a CFDL in a helicon plasma. Combinations of argon-helium, argon-krypton, and argon-xenon gases are ionized and measurements of argon or xenon IVDFs are investigated to determine whether ion acceleration is enhanced (or diminished) by the presence of lighter (or heavier) ions in the mix. We find that the predominant effect is a reduction of ion acceleration consistent with increased drag arising from increased gas pressure under all conditions, including constant total gas pressure, equal plasma densities of different ions, and very different plasma densities of different ions. These results suggest that the physics responsible for acceleration of multiple ion species in simple sheaths is not responsible for the ion acceleration observed in these expanding plasmas. Department of Physics, Gettysburg College.

Irradiation effects in polycarbonate induced by 2.1 GeV Kr ions

International Nuclear Information System (INIS)

Tian Huixian; Jin Yunfan; Zhu Zhiyong; Liu Changlong; Sun Youmei; Wang Zhiguang; Liu Jie; Chen Xiaoxi; Wang Yanbin; Hou Mingdong

2002-01-01

Polycarbonate films were irradiated with 2.1 GeV Kr ions at room temperature in vacuum and in atmosphere, respectively. The ion beam induced effects were studied by means of Fourier transform infrared (FTIR) and ultraviolet visible (UV/VIS) spectroscopies in reflective mode. FTIR measurements indicate that the main effects are bond breaking, chain scissions and bond rearrangement. The creation of alkyne is the result of bond breaking and bond rearrangement. UV/VIS measurements indicate that at wavelengths of 380, 450 and 500 nm, the normalized absorbances follow approximately a linear relationship with the energy deposited density

Acetabular bone density and metal ions after metal-on-metal versus metal-on-polyethylene total hip arthroplasty; short-term results

NARCIS (Netherlands)

Zijlstra, Wierd P.; van der Veen, Hugo C.; van den Akker-Scheek, Inge; Zee, Mark J. M.; Bulstra, Sjoerd K.; van Raay, Jos J. A. M.

Information on periprosthetic acetabular bone density is lacking for metal-on-metal total hip arthroplasties. These bearings use cobalt-chromium instead of titanium acetabular components, which could lead to stress shielding and hence periprosthetic bone loss. Cobalt and chromium ions have

Using precursor ion scan of 184 with liquid chromatography-electrospray ionization-tandem mass spectrometry for concentration normalization in cellular lipidomic studies.

Science.gov (United States)

Chao, Hsi-Chun; Chen, Guan-Yuan; Hsu, Lih-Ching; Liao, Hsiao-Wei; Yang, Sin-Yu; Wang, San-Yuan; Li, Yu-Liang; Tang, Sung-Chun; Tseng, Yufeng Jane; Kuo, Ching-Hua

2017-06-08

Cellular lipidomic studies have been favored approaches in many biomedical research areas. To provide fair comparisons of the studied cells, it is essential to perform normalization of the determined concentration before lipidomic analysis. This study proposed a cellular lipidomic normalization method by measuring the phosphatidylcholine (PC) and sphingomyelin (SM) contents in cell extracts. To provide efficient analysis of PC and SM in cell extracts, flow injection analysis-electrospray ionization-tandem mass spectrometry (FIA-ESI-MS/MS) with a precursor ion scan (PIS) of m/z 184 was used, and the parameters affecting the performance of the method were optimized. Good linearity could be observed between the cell extract dilution factor and the reciprocal of the total ion chromatogram (TIC) area in the PIS of m/z 184 within the dilution range of 1- to 16-fold (R 2  = 0.998). The calibration curve could be used for concentration adjustment of the unknown concentration of a cell extract. The intraday and intermediate precisions were below 10%. The accuracy ranged from 93.0% to 105.6%. The performance of the new normalization method was evaluated using different numbers of HCT-116 cells. Sphingosine, ceramide (d18:1/18:0), SM (d18:1/18:0) and PC (16:1/18:0) were selected as the representative test lipid species, and the results showed that the peak areas of each lipid species obtained from different cell numbers were within a 20% variation after normalization. Finally, the PIS of 184 normalization method was applied to study ischemia-induced neuron injury using oxygen and glucose deprivation (OGD) on primary neuronal cultured cells. Our results showed that the PIS of 184 normalization method is an efficient and effective approach for concentration normalization in cellular lipidomic studies. Copyright © 2017 Elsevier B.V. All rights reserved.

Ion heating, burnout of the high-frequency field, and ion sound generation under the development of a modulation instability of an intense Langmuir wave in a plasma

Science.gov (United States)

Kirichok, A. V.; Kuklin, V. M.; Pryimak, A. V.; Zagorodny, A. G.

2015-09-01

The development of one-dimensional parametric instabilities of intense long plasma waves is considered in terms of the so-called hybrid models, with electrons being treated as a fluid and ions being regarded as particles. The analysis is performed for both cases when the average plasma field energy is lower (Zakharov's hybrid model—ZHM) or greater (Silin's hybrid model—SHM) than the plasma thermal energy. The efficiency of energy transfer to ions and to ion perturbations under the development of the instability is considered for various values of electron-to-ion mass ratios. The energy of low-frequency oscillations (ion-sound waves) is found to be much lower than the final ion kinetic energy. We also discuss the influence of the changes in the damping rate of the high-frequency (HF) field on the instability development. The decrease of the absorption of the HF field inhibits the HF field burnout within plasma density cavities and gives rise to the broadening of the HF spectrum. At the same time, the ion velocity distribution tends to the normal distribution in both ZHM and SHM.

Electron thermalization distances and free-ion yields in dielectric fluids: Effect of electron scavengers

International Nuclear Information System (INIS)

Gee, N.; Freeman, G.R.

1985-01-01

Free-ion yields were measured in isobutane and in solutions containing sulfur hexafluoride, at densities from the liquid at 295 K to the supercritical fluid. A modified Onsager model was used to estimate the most probable thermalization distances b/sub GP/ (GP denotes a Gaussian power-law distribution). The density-normalized distance b/sub GP/d in isobutane increased from 6.3 x 10 -6 kg/m 2 at 295 K to a maximum of 10.5 x 10 -6 kg/m 2 at 395 K, and then decreased to 5.6 x 10 -6 kg/m 2 at 408 K (T/sub c/). The maximum, which is evidence of conduction-band enhancement of b/sub GP/, was suppressed in solutions containing small amounts of SF 6 . The SF 6 captured the electrons while they were still at epithermal energies, and terminated their flight away from their sibling ions. The values of b/sub GP/ and the free-ion yields were thereby decreased

Dispersion- and Exchange-Corrected Density Functional Theory for Sodium Ion Hydration.

Science.gov (United States)

Soniat, Marielle; Rogers, David M; Rempe, Susan B

2015-07-14

A challenge in density functional theory is developing functionals that simultaneously describe intermolecular electron correlation and electron delocalization. Recent exchange-correlation functionals address those two issues by adding corrections important at long ranges: an atom-centered pairwise dispersion term to account for correlation and a modified long-range component of the electron exchange term to correct for delocalization. Here we investigate how those corrections influence the accuracy of binding free energy predictions for sodium-water clusters. We find that the dual-corrected ωB97X-D functional gives cluster binding energies closest to high-level ab initio methods (CCSD(T)). Binding energy decomposition shows that the ωB97X-D functional predicts the smallest ion-water (pairwise) interaction energy and larger multibody contributions for a four-water cluster than most other functionals - a trend consistent with CCSD(T) results. Also, ωB97X-D produces the smallest amounts of charge transfer and the least polarizable waters of the density functionals studied, which mimics the lower polarizability of CCSD. When compared with experimental binding free energies, however, the exchange-corrected CAM-B3LYP functional performs best (error <1 kcal/mol), possibly because of its parametrization to experimental formation enthalpies. For clusters containing more than four waters, "split-shell" coordination must be considered to obtain accurate free energies in comparison with experiment.

Normal Parathyroid Function with Decreased Bone Mineral Density in Treated Celiac Disease

Directory of Open Access Journals (Sweden)

Bernard Lemieux

2001-01-01

Full Text Available Decreased bone mineral density (BMD has been reported in patients with celiac disease in association with secondary hyperparathyroidism. The present study investigated whether basal parathyroid hormone (PTH remained elevated and whether abnormalities of parathyroid function were still present in celiac disease patients treated with a gluten-free diet. Basal seric measurements of calcium and phosphate homeostasis and BMD were obtained in 17 biopsy-proven patients under treatment for a mean period of 5.7±3.7 years (range 1.1 to 15.9. In addition, parathyroid function was studied with calcium chloride and sodium citrate infusions in seven patients. Basal measurements of patients were compared with those of 26 normal individuals, while parathyroid function results were compared with those of seven sex- and age-matched controls. Basal results were similar in patients and controls except for intact PTH (I-PTH (3.77±0.88 pmol/L versus 2.28±0.63 pmol/L, P<0.001, which was higher in the former group but still within normal limits. Mean 25-hydroxy vitamin D and 1,25-dihydroxy vitamin D values were normal in patients. Parathyroid function results were also found to be similar in both groups. Compared with a reference population of the same age (Z score, patients had significantly lower BMDs of the hip (-0.60±0.96 SDs, P<0.05 and lumbar spine (-0.76±1.15 SDs, P<0.05. T scores were also decreased for the hip (-1.3±0.9 SDs, P<0.0001 and lumbar spine (-1.4±1.35 SDs, P<0.0001, with two to three patients being osteoporotic (T score less than -2.5 SDs and seven to eight osteopenic (T score less than -1 SDs but greater than or equal to -2.5 SDs in at least one site. Height and weight were the only important determinants of BMD values by multivariate or logistical regression analysis in these patients. The results show higher basal I-PTH values with normal parathyroid function in treated celiac disease. Height and weight values are, but I-PTH values are not

Nonlinear waves in plasma with negative ion

International Nuclear Information System (INIS)

Saito, Maki; Watanabe, Shinsuke; Tanaca, Hiroshi.

1984-01-01

The propagation of nonlinear ion wave is investigated theoretically in a plasma with electron, positive ion and negative ion. The ion wave of long wavelength is described by a modified K-dV equation instead of a K-dV equation when the nonlinear coefficient of the K-dV equation vanishes at the critical density of negative ion. In the vicinity of the critical density, the ion wave is described by a coupled K-dV and modified K-dV equation. The transition from a compressional soliton to a rarefactive soliton and vice versa are examined by the coupled equation as a function of the negative ion density. The ion wave of short wavelength is described by a nonlinear Schroedinger equation. In the plasma with a negative ion, the nonlinear coefficient of the nonlinear Schroedinger equation changes the sign and the ion wave becomes modulationally unstable. (author)

Perspective on the Role of Negative Ions and Ion-Ion Plasmas in Heavy Ion Fusion Science, Magnetic Fusion Energy,and Related Fields

International Nuclear Information System (INIS)

Grisham, L.R.; Kwan, J.W.

2008-01-01

Some years ago it was suggested that halogen negative ions could offer a feasible alternative path to positive ions as a heavy ion fusion driver beam which would not suffer degradation due to electron accumulation in the accelerator and beam transport system, and which could be converted to a neutral beam by photodetachment near the chamber entrance if desired. Since then, experiments have demonstrated that negative halogen beams can be extracted and accelerated away from the gas plume near the source with a surviving current density close to what could be achieved with a positive ion of similar mass, and with comparable optical quality. In demonstrating the feasibility of halogen negative ions as heavy ion driver beams, ion - ion plasmas, an interesting and somewhat novel state of matter, were produced. These plasmas, produced near the extractor plane of the sources, appear, based upon many lines of experimental evidence, to consist of almost equal densities of positive and negative chlorine ions, with only a small component of free electrons. Serendipitously, the need to extract beams from this plasma for driver development provides a unique diagnostic tool to investigate the plasma, since each component - positive ions, negative ions, and electrons - can be extracted and measured separately. We discuss the relevance of these observations to understanding negative ion beam extraction from electronegative plasmas such as halogens, or the more familiar hydrogen of magnetic fusion ion sources. We suggest a concept which might improve negative hydrogen extraction by the addition of a halogen. The possibility and challenges of producing ion - ion plasmas with thin targets of halogens or, perhaps, salt, is briefly addressed.

Perspective on the Role of Negative Ions and Ion-Ion Plasmas in Heavy Ion Fusion Science, Magnetic Fusion Energy, and Related Fields

International Nuclear Information System (INIS)

Grisham, L.R.; Kwan, J.W.

2008-01-01

Some years ago it was suggested that halogen negative ions (1)could offer a feasible alternative path to positive ions as a heavy ion fusion driver beam which would not suffer degradation due to electron accumulation in the accelerator and beam transport system, and which could be converted to a neutral beam by photodetachment near the chamber entrance if desired. Since then, experiments have demonstrated that negative halogen beams can be extracted and accelerated away from the gas plume near the source with a surviving current density close to what could be achieved with a positive ion of similar mass, and with comparable optical quality. In demonstrating the feasibility of halogen negative ions as heavy ion driver beams, ion-ion plasmas, an interesting and somewhat novel state of matter, were produced. These plasmas, produced near the extractor plane of the sources, appear, based upon many lines of experimental evidence, to consist of almost equal densities of positive and negative chlorine ions, with only a small component of free electrons. Serendipitously, the need to extract beams from this plasma for driver development provides a unique diagnostic tool to investigate the plasma, since each component--positive ions, negative ions, and electrons--can be extracted and measured separately. We discuss the relevance of these observations to understanding negative ion beam extraction from electronegative plasmas such as halogens, or the more familiar hydrogen of magnetic fusion ion sources. We suggest a concept which might improve negative hydrogen extraction by the addition of a halogen. The possibility and challenges of producing ion-ion plasmas with thin targets of halogens or, perhaps, salt, is briefly addressed

Consideration of beam plasma ion-source

International Nuclear Information System (INIS)

Sano, Fumimichi; Kusano, Norimasa; Ishida, Yoshihiro; Ishikawa, Junzo; Takagi, Toshinori

1976-01-01

Theoretical and experimental analyses and their comparison were made on the plasma generation and on the beam extraction for the beam plasma ion-source. The operational principle and the structure of the ion-source are explained in the first part. Considerations are given on the electron beam-plasma interaction and the resulting generation of high frequency or microwaves which in turn increases the plasma density. The flow of energy in this system is also explained in the second part. The relation between plasma density and the imaginary part of frequency is given by taking the magnetic flux density, the electron beam energy, and the electron beam current as parameters. The relations between the potential difference between collector and drift tube and the plasma density or the ion-current are also given. Considerations are also given to the change of the plasma density due to the change of the magnetic flux density at drift tube, the change of the electron beam energy, and the change of the electron beam current. The third part deals with the extraction characteristics of the ion beam. The structure of the multiple-aperture electrode and the relation between plasma density and the extracted ion current are explained. (Aoki, K.)

Emittance measurements for optimum operation of the J-PARC RF-driven H{sup −} ion source

Energy Technology Data Exchange (ETDEWEB)

Ueno, A., E-mail: akira.ueno@j-parc.jp; Ohkoshi, K.; Ikegami, K.; Takagi, A.; Yamazaki, S.; Oguri, H. [J-PARC Center, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan)

2015-04-08

In order to satisfy the Japan Proton Accelerator Research Complex (J-PARC) second stage requirements of an H{sup −} ion beam of 60mA within normalized emittances of 1.5πmm•mrad both horizontally and vertically, a flat top beam duty factor of 1.25% (500μs×25Hz) and a life-time of longer than 1month, the J-PARC cesiated RF-driven H{sup −} ion source was developed by using an internal-antenna developed at the Spallation Neutron Source (SNS). The transverse emittances of the source were measured with various conditions to find out the optimum operation conditions minimizing the horizontal and vertical rms normalized emittances. The transverse emittances were most effectively reduced by operating the source with the plasma electrode temperature lower than 70°C. The optimum value of the cesium (Cs) density around the beam hole of the plasma electrode seems to be proportional to the plasma electrode temperature. The fine control of the Cs density is indispensable, since the emittances seem to increase proportionally to the excessiveness of the Cs density. Furthermore, the source should be operated with the Cs density beyond a threshold value, since the plasma meniscus shape and the ellipse parameters of the transverse emittances seem to be changed step-function-likely on the threshold Cs value.

An RF ion source based primary ion gun for secondary ion mass spectroscopy

International Nuclear Information System (INIS)

Menon, Ranjini; Nabhiraj, P.Y.; Bhandari, R.K.

2011-01-01

In this article we present the design, development and characterization of an RF plasma based ion gun as a primary ion gun for SIMS application. RF ion sources, in particular Inductively Coupled Plasma (ICP) ion sources are superior compared to LMIS and duoplasmtron ion sources since they are filamentless, can produce ions of gaseous elements. At the same time, ICP ion sources offer high angular current density which is an important factor in producing high current in small spot size on the target. These high current microprobes improve the signal to noise ratio by three orders as compared to low current ion sources such as LMIS. In addition, the high current microprobes have higher surface and depth profiling speeds. In this article we describe a simple ion source in its very basic form, two lens optical column and characteristics of microprobe

Recent US advances in ion-beam-driven high energy density physics and heavy ion fusion

International Nuclear Information System (INIS)

Logan, B.G.; Bieniosek, F.M.; Celata, C.M.; Coleman, J.; Greenway, W.; Henestroza, E.; Kwan, J.W.; Lee, E.P.; Leitner, M.; Roy, P.K.; Seidl, P.A.; Vay, J.-L.; Waldron, W.L.; Yu, S.S.; Barnard, J.J.; Cohen, R.H.; Friedman, A.; Grote, D.P.; Kireeff Covo, M.; Molvik, A.W.; Lund, S.M.; Meier, W.R.; Sharp, W.; Davidson, R.C.; Efthimion, P.C.; Gilson, E.P.; Grisham, L.; Kaganovich, I.D.; Qin, H.; Sefkow, A.B.; Startsev, E.A.; Welch, D.; Olson, C.

2007-01-01

During the past two years, significant experimental and theoretical progress has been made in the US heavy ion fusion science program in longitudinal beam compression, ion-beam-driven warm dense matter, beam acceleration, high brightness beam transport, and advanced theory and numerical simulations. Innovations in longitudinal compression of intense ion beams by >50X propagating through background plasma enable initial beam target experiments in warm dense matter to begin within the next two years. We are assessing how these new techniques might apply to heavy ion fusion drivers for inertial fusion energy

Development of Functional Surfaces on High-Density Polyethylene (HDPE) via Gas-Assisted Etching (GAE) Using Focused Ion Beams.

Science.gov (United States)

Sezen, Meltem; Bakan, Feray

2015-12-01

Irradiation damage, caused by the use of beams in electron and ion microscopes, leads to undesired physical/chemical material property changes or uncontrollable modification of structures. Particularly, soft matter such as polymers or biological materials is highly susceptible and very much prone to react on electron/ion beam irradiation. Nevertheless, it is possible to turn degradation-dependent physical/chemical changes from negative to positive use when materials are intentionally exposed to beams. Especially, controllable surface modification allows tuning of surface properties for targeted purposes and thus provides the use of ultimate materials and their systems at the micro/nanoscale for creating functional surfaces. In this work, XeF2 and I2 gases were used in the focused ion beam scanning electron microscope instrument in combination with gallium ion etching of high-density polyethylene surfaces with different beam currents and accordingly different gas exposure times resulting at the same ion dose to optimize and develop new polymer surface properties and to create functional polymer surfaces. Alterations in the surface morphologies and surface chemistry due to gas-assisted etching-based nanostructuring with various processing parameters were tracked using high-resolution SEM imaging, complementary energy-dispersive spectroscopic analyses, and atomic force microscopic investigations.

Angular dependence of SiO2 etch rate at various bias voltages in a high density CHF3 plasma

International Nuclear Information System (INIS)

Lee, Gyeo-Re; Hwang, Sung-Wook; Min, Jae-Ho; Moon, Sang Heup

2002-01-01

The dependence of the SiO 2 etch rate on the angle of ions incident on the substrate surface was studied over a bias voltage range from -20 to -600 V in a high-density CHF 3 plasma using a Faraday cage to control the ion incident angle. The effect of the bottom plane on the sidewall etching was also examined. Differences in the characteristics of the etch rate as a function of the ion angle were observed for different bias voltage regions. When the absolute value of the bias voltage was smaller than 200 V, the normalized etch rate (NER) defined as the etch rate normalized by the rate on the horizontal surface, changed following a cosine curve with respect to the ion incident angle, defined as the angle between the ion direction and the normal of the substrate surface. When the magnitude of the bias voltage was larger than 200 V, the NER was deviated to higher values from those given by a cosine curve at ion angles between 30 deg. and 70 deg. , and then drastically decreased at angles higher than 70 deg. until a net deposition was observed at angles near 90 deg. . The characteristic etch-rate patterns at ion angles below 70 deg. were determined by the ion energy transferred to the surface, which affected the SiO 2 etch rate and, simultaneously, the rate of removal of a fluorocarbon polymer film formed on the substrate surface. At high ion angles, particles emitted from the bottom plane contributed to polymer formation on and affected the etching characteristics of the substrate

Gas discharge ion source. II. Duopigatron

International Nuclear Information System (INIS)

Bacon, F.M.; Bickes, R.W. Jr.; O'Hagan, J.B.

1978-01-01

Ion source performance characteristics consisting of total ion current, ion energy distribution, mass distribution, and ion current density distribution have been measured for several models of a duopigatron. Variations on the duopigatron design involved plasma expansion cup material and dimensions, secondary cathode material, and interelectrode spacings. Of the designs tested, the one with a copper and molybdenum secondary cathode, and a mild steel plasma expansion cup proved to give the best results. The ion current density distribution was peaked at the center of the plasma expansion cup and fell off to 80% of the peak value at the cup wall for a cup 15.2 mm deep. A total ion current of 180 mA consisting of 60%-70% atomic ions was produced with an arc current of 20 A and source pressure of 9.3 Pa. More shallow cups produced a larger beam current and a more sharply peaked ion current density distribution. Typical ion energy distributions were bellshaped curves with a peak 10-20 V below anode potential and with ion energies extending 30-40 V on either side of the peak

Ion heating in minority ICRH experiments on JET

International Nuclear Information System (INIS)

Start, D.F.H.; Bhatnagar, V.; Bures, M.

1991-06-01

Bulk ion heating by high power H-minority ICRH has been demonstrated in JET during both pellet enhanced performance H-mode experiments (PEP + H - mode) and in density limit studies. In the PEP + H - mode plasmas the electron and ion temperatures both reached 10 keV at an electron density of 7 x 10 19 /m 3 . According to Fokker-Planck calculations the power from the minority was transfered almost equally to the electrons and majority ions as a result of both the high electron density, n e , and the high minority density, n h , (n h /n e ≅ 0.15). For the first time with ICRH on JET a central ion temperature greater than the central electron temperature was achieved. In the density limit experiments which involved strong gas puffing into limiter discharges, there was strong evidence of a transfer from electron heating to ion heating as the electron density was ramped up to 8 x 10 19 /m 3 . (Author)

Low emittance 0.8A K+ ion source for the LBL Induction Linac System Experiment (ILSE)

International Nuclear Information System (INIS)

Eylon, S.; Henestroza, E.; Chupp, W.W.; Yu, S.

1993-05-01

A high current injector for heavy ion fusion presently under construction at Lawrence Berkeley Laboratory requires large sources of up to 17 an in diameter and total potassium ion current of 790 mA with a low normalized transverse emittance of less than 0.5 mm-mr. A 1 in. diameter hot alumina silicate (zeolite) source was fabricated and tested in the injector setup of SBTE, an existing facility at LBL. Initial measurements showed a maximum space charge limited ion current of 95 mA. The corresponding density of 19 mA/cm 2 was limited by the source diode optics and not be the source emission. The density required for the high current injector is 4 mA/cm 2 . The normalized emittance was measured to be 0.06 mm-mrad, corresponding to a transverse temperature of 0.2 eV. Non-destructive life tests showed that the source can be operated under continuous operating conditions of the high current injector for more than a month (twenty eight-hour days, with 1 μs long pulses at 1 Hz). D.C. destructive life tests showed that ∼30% of the total stored K can be ionized and extracted, allowing, in principle, for years of operation for the high current injector. Furthermore, we shall describe the extension of the fabricating technique to large diameter sources (up to 17 cm) and report on measured ion emission performance, measured surface temperature uniformity and heating power considerations

On the Chemistry of Hydrides of N Atoms and O+ Ions

Science.gov (United States)

Awad, Zainab; Viti, Serena; Williams, David A.

2016-08-01

Previous work by various authors has suggested that the detection by Herschel/HIFI of nitrogen hydrides along the low-density lines of sight toward G10.6-0.4 (W31C) cannot be accounted for by gas-phase chemical models. In this paper we investigate the role of surface reactions on dust grains in diffuse regions, and we find that formation of the hydrides by surface reactions on dust grains with efficiency comparable to that for H2 formation reconciles models with observations of nitrogen hydrides. However, similar surface reactions do not contribute significantly to the hydrides of O+ ions detected by Herschel/HIFI that are present along many sight lines in the Galaxy. The O+ hydrides can be accounted for by conventional gas-phase chemistry either in diffuse clouds of very low density with normal cosmic-ray fluxes or in somewhat denser diffuse clouds with high cosmic-ray fluxes. Hydride chemistry in dense dark clouds appears to be dominated by gas-phase ion-molecule reactions.

Carbonation of wollastonite(001) competing hydration: microscopic insights from ion spectroscopy and density functional theory.

Science.gov (United States)

Longo, Roberto C; Cho, Kyeongjae; Brüner, Philipp; Welle, Alexander; Gerdes, Andreas; Thissen, Peter

2015-03-04

In this paper, we report about the influence of the chemical potential of water on the carbonation reaction of wollastonite (CaSiO3) as a model surface of cement and concrete. Total energy calculations based on density functional theory combined with kinetic barrier predictions based on nudge elastic band method show that the exposure of the water-free wollastonite surface to CO2 results in a barrier-less carbonation. CO2 reacts with the surface oxygen and forms carbonate (CO3(2-)) complexes together with a major reconstruction of the surface. The reaction comes to a standstill after one carbonate monolayer has been formed. In case one water monolayer is covering the wollastonite surface, the carbonation is no more barrier-less, yet ending in a localized monolayer. Covered with multilayers of water, the thermodynamic ground state of the wollastonite completely changes due to a metal-proton exchange reaction (also called early stage hydration) and Ca(2+) ions are partially removed from solid phase into the H2O/wollastonite interface. Mobile Ca(2+) reacts again with CO2 and forms carbonate complexes, ending in a delocalized layer. By means of high-resolution time-of-flight secondary-ion mass spectrometry images, we confirm that hydration can lead to a partially delocalization of Ca(2+) ions on wollastonite surfaces. Finally, we evaluate the impact of our model surface results by the meaning of low-energy ion-scattering spectroscopy combined with careful discussion about the competing reactions of carbonation vs hydration.

Current interruption by density depression

International Nuclear Information System (INIS)

Wagner, J.S.; Tajima, T.; Akasofu, S.I.

1985-04-01

Using a one-dimensional electrostatic particle code, we examine processes associated with current interruption in a collisionless plasma when a density depression is present along the current channel. Current interruption due to double layers was suggested by Alfven and Carlqvist (1967) as a cause of solar flares. At a local density depression, plasma instabilities caused by an electron current flow are accentuated, leading to current disruption. Our simulation study encompasses a wide range of the parameters in such a way that under appropriate conditions, both the Alfven and Carlqvist (1967) regime and the Smith and Priest (1972) regime take place. In the latter regime the density depression decays into a stationary structure (''ion-acoustic layer'') which spawns a series of ion-acoustic ''solitons'' and ion phase space holes travelling upstream. A large inductance of the current circuit tends to enhance the plasma instabilities

Hidden ion population: Revisited

International Nuclear Information System (INIS)

Olsen, R.C.; Chappell, C.R.; Gallagher, D.L.; Green, J.L.; Gurnett, D.A.

1985-01-01

Satellite potentials in the outer plasmasphere range from near zero to +5 to +10 V. Under such conditions ion measurements may not include the low energy core of the plasma population. In eclipse, the photoelectron current drops to zero, and the spacecraft potential can drop to near zero volts. In regions where the ambient plasma density is below 100 cm -3 , previously unobserved portions of the ambient plasma distribution function can become visible in eclipse. A survey of the data obtained from the retarding ion mass spectrometer (RIMS) on Dynamics Explorer 1 shows that the RIMS detector generally measured the isotropic background in both sunlight and eclipse in the plasma-sphere. Absolute density measurements for the ''hidden'' ion population are obtained for the first time using the plasma wave instrument observations of the upper hybrid resonance. Agreement in total density is found in sunlight and eclipse measurements at densities above 80 cm -3 . In eclipse, agreement is found at densities as low as 20 cm -3 . The isotropic plasma composition is primarily H + , with approx.10% He + , and 0.1 to 1.0% O + . A low energy field-aligned ion population appears in eclipse measurements outside the plasmasphere, which is obscured in sunlight. These field-aligned ions can be interpreted as field-aligned flows with densities of a few particles per cubic centimeter, flowing at 5-20 km/s. The problem in measuring these field-aligned flows in sunlight is the masking of the high energy tail of the field-aligned distribution by the isotropic background. Effective measurement of the core of the magnetospheric plasma distribution awaits satellites with active means of controlling the satellite potential

Ion sources for heavy ion fusion

International Nuclear Information System (INIS)

Yu, S.S.; Eylon, S.; Chupp, W.

1995-09-01

The development of ion sources for heavy ion fusion will be reported with particular emphasis on a recently built 2 MV injector. The new injector is based on an electrostatic quadrupole configuration, and has produced pulsed K + ions of 950 mA peak from a 6.7 inch curved alumino silicate source. The ion beam has reached 2.3 MV with an energy flatness of ±0.2% over 1 micros. The measured normalized edge emittance of less than 1 π mm-mr is close to the source temperature limit. The design, construction, performance, and comparisons with three-dimensional particle-in-cell simulations will be described

Development of exploding wire ion source for intense pulsed heavy ion beam accelerator

International Nuclear Information System (INIS)

Ochiai, Y.; Murata, T.; Ito, H.; Masugata, K.

2012-01-01

A Novel exploding wire type ion source device is proposed as a metallic ion source of intense pulsed heavy ion beam (PHIB) accelerator. In the device multiple shot operations is realized without breaking the vacuum. The basic characteristics of the device are evaluated experimentally with an aluminum wire of diameter 0.2 mm, length 25 mm. Capacitor bank of capacitance 3 μF, charging voltage 30 kV was used and the wire was successfully exploded by a discharge current of 15 kA, rise time 5.3 μs. Plasma flux of ion current density around 70 A/cm 2 was obtained at 150 mm downstream from the device. The drift velocity of ions evaluated by a time-of-flight method was 2.7x10 4 m/sec, which corresponds to the kinetic energy of 100 eV for aluminum ions. From the measurement of ion current density distribution ion flow is found to be concentrated to the direction where ion acceleration gap is placed. From the experiment the device is found to be acceptable for applying PHIB accelerator. (author)

Lithium and sodium ion capacitors with high energy and power densities based on carbons from recycled olive pits

Science.gov (United States)

Ajuria, Jon; Redondo, Edurne; Arnaiz, Maria; Mysyk, Roman; Rojo, Teófilo; Goikolea, Eider

2017-08-01

In this work, we are presenting both lithium and sodium ion capacitors (LIC and NIC) entirely based on electrodes designed from recycled olive pit bio-waste derived carbon materials. On the one hand, olive pits were pyrolized to obtain a low specific surface area semigraphitic hard carbon to be used as the ion intercalation (battery-type) negative electrode. On the other hand, the same hard carbon was chemically activated with KOH to obtain a high specific surface area activated carbon that was further used as the ion-adsorption (capacitor-type) positive electrode. Both electrodes were custom-made to be assembled in a hybrid cell to either build a LIC or NIC in the corresponding Li- and Na-based electrolytes. For comparison purposes, a symmetric EDLC supercapacitor cell using the same activated carbon in 1.5 M Et4NBF4/acetonitrile electrolyte was also built. Both LIC and NIC systems demonstrate remarkable energy and power density enhancement over its EDLC counterpart while showing good cycle life. This breakthrough offers the possibility to easily fabricate versatile hybrid ion capacitors, covering a wide variety of applications where different requirements are demanded.

Multiply gapped density of states in a normal metal in contact with a superconductor

Energy Technology Data Exchange (ETDEWEB)

Reutlinger, Johannes; Belzig, Wolfgang [Department of Physics, University of Konstanz, 78457 Konstanz (Germany); Nazarov, Yuli V. [Kavli Institute of Nanoscience Delft, Delft University of Technology, 2628 CJ Delft (Netherlands); Glazman, Leonid I. [Department of Physics, Yale University, New Haven CT 06511-8499 (United States)

2012-07-01

The spectral properties of a normal metal adjacent to a superconductor are strongly dependent on the characteristic mesoscopic energy scale - the Thouless energy E{sub Th} - and the strength of the connection. In this work, we predict that the local density of states (LDOS), besides the well know minigap {proportional_to}E{sub Th}, can exhibit a multiple gap structure, which strongly depends on the type of the contact. For ballistic contacts we calculate these secondary gaps analytically in the framework of quantum circuit theory of mesoscopic transport. The secondary gaps are absent in the case of tunnel contacts. In the general case the equations are solved numerically for more realistic contacts, like for example diffusive connectors or dirty interfaces, which are characterized by continuous distributions of transmission eigenvalues between 0 and 1. We find that the gap vanishes in these cases, but the density of states is still suppressed around the superconducting gap edge. Distribution functions with a stronger weight at higher transmissions can be modeled through asymmetric ballistic double junctions, which even exhibit multiple gaps. Such spectral signatures are fundamental to disordered nanoscopic conductors and experimentally accessible.

High energy density in matter produced by heavy ion beams

International Nuclear Information System (INIS)

1986-05-01

In this report the activities of the GSI Darmstadt (FRG) during 1985 concerning inertial confinement fusion by heavy ion beams. Short communications and abstracts are presented concerning a Z-pinch experiment, heavy ion pumped lasers and X-ray spectroscopy, the study of ion-ion collisions, a RFQ development and beam transport studies, accelerator theory, targets for SIS/ESR experiments, the rayleigh-Taylor instability, studies on the equation of state for matter under high pressure, as well as the development of computer codes. (HSI)

Effect of ion orbit loss on the structure in the H-mode tokamak edge pedestal profiles of rotation velocity, radial electric field, density, and temperature

International Nuclear Information System (INIS)

Stacey, Weston M.

2013-01-01

An investigation of the effect of ion orbit loss of thermal ions and the compensating return ion current directly on the radial ion flux flowing in the plasma, and thereby indirectly on the toroidal and poloidal rotation velocity profiles, the radial electric field, density, and temperature profiles, and the interpretation of diffusive and non-diffusive transport coefficients in the plasma edge, is described. Illustrative calculations for a high-confinement H-mode DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] plasma are presented and compared with experimental results. Taking into account, ion orbit loss of thermal ions and the compensating return ion current is found to have a significant effect on the structure of the radial profiles of these quantities in the edge plasma, indicating the necessity of taking ion orbit loss effects into account in interpreting or predicting these quantities

Behavior of lithium ions in the turbulent near-wall tokamak plasma under heating of ions and electrons of the main plasma

International Nuclear Information System (INIS)

Shurygin, R. V.; Morozov, D. Kh.

2014-01-01

Turbulent dynamics of the near-wall tokamak plasma is simulated by numerically solving the nonlinear reduced Braginskii magnetohydrodynamic equations with allowance for a lithium ion admixture. The effects of turbulence and radiation of the admixture are analyzed in the framework of a self-consistent approach. The radial distributions of the radiative loss power and the density of Li 0 atoms and Li +1 ions are obtained as functions of the electron and ion temperatures of the main plasma in the near-wall layer. The results of numerical simulations show that supply of lithium ions into the low-temperature near-wall plasma substantially depends on whether the additional power is deposited into the electron or ion component of the main plasma. If the electron temperature in the layer increases (ECR heating), then the ion density drops. At the same time, an increase in the temperature of the main ions (ICR heating) leads to an increase in the density of Li +1 ions. The results of numerical simulations are explained by the different influence of the electron and ion temperatures on the atomic processes governing the accumulation and loss of particles in the balance equations for neutral Li 0 atoms and Li +1 ions in the admixture. The radial profile of the electron temperature and the corresponding distribution of the radiative loss power for different densities of neutral Li 0 atoms on the wall are obtained. The calculations show that the presence of Li +1 ions affects turbulent transport of the main ions. In this case, the electron heat flux increases by 20–30% with increasing Li +1 density, whereas the flux of the main ions drops by nearly the same amount. The radial profile of the turbulent flux of lithium ions is obtained. It is demonstrated that the appearance of the pinch effect is related to the positive density gradient of lithium ions across the calculation layer. For the parameters of the T-10 tokamak, the effect of radiative cooling of the near-wall plasma

Ion thermal conductivity and convective energy transport in JET hot-ion regimes and H-modes

International Nuclear Information System (INIS)

Tibone, F.; Balet, B.; Cordey, J.G.

1989-01-01

Local transport in a recent series of JET experiments has been studied using interpretive codes. Auxiliary heating, mainly via neutral beam injection, was applied on low-density target plasmas confined in the double-null X-point configuration. This has produced two-component plasmas with high ion temperature and neutron yield and, above a threshold density, H-modes characterised by peak density and power deposition profiles. H-mode confinement was also obtained for the first time with 25 MW auxiliary power, of which 10 MW was from ion cyclotron resonance heating. We have used profile measurements of electron temperature T e from electron cyclotron emission and LIDAR Thomson scattering, ion temperature T i from charge-exchange recombination spectroscopy (during NBI), electron density n e from LIDAR and Abel-inverted interferometer measurements. Only sparse information is, however, available to date concerning radial profiles of effective ionic charge and radiation losses. Deuterium depletion due to high impurity levels is an important effect in these discharges, and our interpretation of thermal ion energy content, neutron yield and ion particle fluxes needs to be confirmed using measured Z eff -profiles. (author) 4 refs., 4 figs

Ion heating, burnout of the high-frequency field, and ion sound generation under the development of a modulation instability of an intense Langmuir wave in a plasma

Energy Technology Data Exchange (ETDEWEB)

Kirichok, A. V., E-mail: sandyrcs@gmail.com; Kuklin, V. M.; Pryimak, A. V. [Institute for High Technologies, V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61022 (Ukraine); Zagorodny, A. G. [Bogolyubov Institute for Theoretical Physics, 14-b, Metrolohichna str., Kiev 03680 (Ukraine)

2015-09-15

The development of one-dimensional parametric instabilities of intense long plasma waves is considered in terms of the so-called hybrid models, with electrons being treated as a fluid and ions being regarded as particles. The analysis is performed for both cases when the average plasma field energy is lower (Zakharov's hybrid model—ZHM) or greater (Silin's hybrid model—SHM) than the plasma thermal energy. The efficiency of energy transfer to ions and to ion perturbations under the development of the instability is considered for various values of electron-to-ion mass ratios. The energy of low-frequency oscillations (ion-sound waves) is found to be much lower than the final ion kinetic energy. We also discuss the influence of the changes in the damping rate of the high-frequency (HF) field on the instability development. The decrease of the absorption of the HF field inhibits the HF field burnout within plasma density cavities and gives rise to the broadening of the HF spectrum. At the same time, the ion velocity distribution tends to the normal distribution in both ZHM and SHM.

Impurity transport model for the normal confinement and high density H-mode discharges in Wendelstein 7-AS

International Nuclear Information System (INIS)

Ida, K; Burhenn, R; McCormick, K; Pasch, E; Yamada, H; Yoshinuma, M; Inagaki, S; Murakami, S; Osakabe, M; Liang, Y; Brakel, R; Ehmler, H; Giannone, L; Grigull, P; Knauer, J P; Maassberg, H; Weller, A

2003-01-01

An impurity transport model based on diffusivity and the radial convective velocity is proposed as a first approach to explain the differences in the time evolution of Al XII (0.776 nm), Al XI (55 nm) and Al X (33.3 nm) lines following Al-injection by laser blow-off between normal confinement discharges and high density H-mode (HDH) discharges. Both discharge types are in the collisional regime for impurities (central electron temperature is 0.4 keV and central density exceeds 10 20 m -3 ). In this model, the radial convective velocity is assumed to be determined by the radial electric field, as derived from the pressure gradient. The diffusivity coefficient is chosen to be constant in the plasma core but is significantly larger in the edge region, where it counteracts the high local values of the inward convective velocity. Under these conditions, the faster decay of aluminium in HDH discharges can be explained by the smaller negative electric field in the bulk plasma, and correspondingly smaller inward convective velocity, due to flattening of the density profiles

Plasma immersion ion implantation of the interior surface of a large cylindrical bore using an auxiliary electrode

International Nuclear Information System (INIS)

Zeng, X.C.; Kwok, T.K.; Liu, A.G.; Chu, P.K.; Tang, B.Y.

1998-01-01

A model utilizing cold, unmagnetized, and collisionless fluid ions as well as Boltzmann electrons is used to comprehensively investigate the sheath expansion into a translationally invariant large bore in the presence of an auxiliary electrode during plasma immersion ion implantation (PIII) of a cylindrical bore sample. The governing equation of ion continuity, ion motion, and Poisson close-quote s equation are solved by using a numerical finite difference method for different cylindrical bore radii, auxiliary electrode radii, and voltage rise times. The ion density and ion impact energy at the cylindrical inner surface, as well as the ion energy distribution, maximum ion impact energy, and average ion impact energy for the various cases are obtained. Our results show a dramatic improvement in the impact energy when an auxiliary electrode is used and the recommended normalized auxiliary electrode radius is in the range of 0.1 endash 0.3. copyright 1998 American Institute of Physics

Lower-hybrid (LH) oscillitons evolved from ion-acoustic (IA)/ion-cyclotron (IC) solitary waves: effect of electron inertia

Science.gov (United States)

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

2010-05-01

Lower-hybrid (LH) oscillitons reveal one aspect of geocomplexities. They have been observed by rockets and satellites in various regions in geospace. They are extraordinary solitary waves the envelop of which has a relatively longer period, while the amplitude is modulated violently by embedded oscillations of much shorter periods. We employ a two-fluid (electron-ion) slab model in a Cartesian geometry to expose the excitation of LH oscillitons. Relying on a set of self-similar equations, we first produce, as a reference, the well-known three shapes (sinusoidal, sawtooth, and spiky or bipolar) of parallel-propagating ion-acoustic (IA) solitary structures in the absence of electron inertia, along with their Fast Fourier Transform (FFT) power spectra. The study is then expanded to illustrate distorted structures of the IA modes by taking into account all the three components of variables. In this case, the ion-cyclotron (IC) mode comes into play. Furthermore, the electron inertia is incorporated in the equations. It is found that the inertia modulates the coupled IA/IC envelops to produce LH oscillitons. The newly excited structures are characterized by a normal low-frequency IC solitary envelop embedded by high-frequency, small-amplitude LH oscillations which are superimposed upon by higher-frequency but smaller-amplitude IA ingredients. The oscillitons are shown to be sensitive to several input parameters (e.g., the Mach number, the electron-ion mass/temperature ratios, and the electron thermal speed). Interestingly, whenever a LH oscilliton is triggered, there occurs a density cavity the depth of which can reach up to 20% of the background density, along with density humps on both sides of the cavity. Unexpectedly, a mode at much lower frequencies is also found beyond the IC band. Future studies are finally highlighted. The appendices give a general dispersion relation and specific ones of linear modes relevant to all the nonlinear modes encountered in the text.

Particle acceleration in near critical density plasma

International Nuclear Information System (INIS)

Gu, Y.J.; Kong, Q.; Kawata, S.; Izumiyama, T.; Nagashima, T.

2013-01-01

Charged particle acceleration schemes driven by ultra intense laser and near critical density plasma interactions are presented. They include electron acceleration in a plasma channel, ion acceleration by the Coulomb explosion and high energy electron beam driven ion acceleration. It is found that under the near critical density plasma both ions and electrons are accelerated with a high acceleration gradient. The electron beam containing a large charge quantity is accelerated well with 23 GeV/cm. The collimated ion bunch reaches 1 GeV. The investigations and discussions are based on 2.5D PIC (particle-in-cell) simulations. (author)

Conductivity of ion dielectrics during the mean flux-density electron- and X-ray pulse radiation

International Nuclear Information System (INIS)

Vajsburd, D.I.; Mesyats, G.A.; Naminov, V.L.; Tavanov, Eh.G.

1982-01-01

Conductivity of ion dielectrics under electron and X-ray pulse radiation is investigated. Investigations have been conducted in the range of average beam densities in which extinction of low-energy conductivity takes place. Thin plates of alkali-halogen crystals have been used as samples. Small-dimensional accelerator with controlled beam parameters: 1-20 ns, 0.1-2000 A/cm 2 , 0.3-0.5 MeV has been used for radiation. Temperature dependence of conductivity current pulse is determined. Time resolution of 10 - 10 s is achieved. In the 70-300 K range it practically coincides with radiation pulse. An essential inertial constituent is observed below 300 K. It is shown that at average beam densities a comparable contribution into fast conductivity is made by intracentre conductivity independent of temperature and high-temperature conductivity which decreases with temperature with activation energy equal to the energy of short-wave background. That is why amplitude of fast constituent decreases with temperature slower than high-energy conductivity

Ion-temperature-gradient-driven modes in bi-ion magnetoplasma

Energy Technology Data Exchange (ETDEWEB)

Batool, Nazia; Mirza, Arshad M [Theoretical Plasma Physics Group, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Qamar, Anisa [Department of Physics, Peshawar University, NWFP 25120 (Pakistan)], E-mail: nazia.batool@ncp.edu.pk

2008-12-15

The toroidal ion-temperature-gradient (ITG)-driven electrostatic drift waves are investigated for bi-ion plasmas with equilibrium density, temperature and magnetic field gradients. Using Braginskii's transport equations for the ions and Boltzmann distributed electrons, the mode coupling equations are derived. New ITG-driven modes are shown to exist. The results of the present study should be helpful to understand several wave phenomena in space and tokamak plasmas.

Energy dependence of angular distributions of sputtered particles by ion-beam bombardment at normal incidence

International Nuclear Information System (INIS)

Matsuda, Yoshinobu; Ueda, Yasutoshi; Uchino, Kiichiro; Muraoka, Katsunori; Maeda, Mitsuo; Akazaki, Masanori; Yamamura, Yasunori.

1986-01-01

The angular distributions of sputtered Fe-atoms were measured using the laser fluorescence technique during Ar-ion bombardment for energies of 0.6, 1, 2 and 3 keV at normal incidence. The measured cosine distribution at 0.6 keV progressively deviated to an over-cosine distribution at higher energies, and at 3 keV the angular distribution was an overcosine distribution of about 20 %. The experimental results agree qualitatively with calculations by a recent computer simulation code, ACAT. The results are explained by the competition between surface scattering and the effects of primary knock-on atoms, which tend to make the angular distributions over-cosine and under-cosine, respectively. (author)

Simulation and design of an electron beam ion source charge breeder for the californium rare isotope breeder upgrade

Directory of Open Access Journals (Sweden)

Clayton Dickerson

2013-02-01

Full Text Available An electron beam ion source (EBIS will be constructed and used to charge breed ions from the californium rare isotope breeder upgrade (CARIBU for postacceleration into the Argonne tandem linear accelerator system (ATLAS. Simulations of the EBIS charge breeder performance and the related ion transport systems are reported. Propagation of the electron beam through the EBIS was verified, and the anticipated incident power density within the electron collector was identified. The full normalized acceptance of the charge breeder with a 2 A electron beam, 0.024π  mm mrad for nominal operating parameters, was determined by simulating ion injection into the EBIS. The optics of the ion transport lines were carefully optimized to achieve well-matched ion injection, to minimize emittance growth of the injected and extracted ion beams, and to enable adequate testing of the charge bred ions prior to installation in ATLAS.

Gas Transport and Density Control in the HYLIFE Heavy-Ion Beam Lines

International Nuclear Information System (INIS)

Debonnel, Christophe S.; Welch, Dale R.; Rose, David V.; Lawrence, Simon S.Yu; Peterson, Per F.

2003-01-01

The effective propagation and focusing of heavy-ion beams in the final-focus magnet region of inertial fusion target chambers require controlling the background gas density and pressure in the beam tubes. Liquid vortexes will coat the inside of the tubes next to the beam ports and will help eliminate the need for mechanical shutters to mitigate the venting of target chamber background gas into the final-focus magnet region. Before the neutralizing region, the beam space charge is high, and ablation and target debris deposition in the final-focus magnet region may cause voltage breakdown. Previous studies focused on evaluating the amount of target chamber debris reaching the entrance of the beam ports. The TSUNAMI code has now been used to assess the density, temperature, and velocity of the vortex debris transported ∼3 m up the beam tubes and reaching the final-focus magnet region, assuming that the liquid vortexes are perfectly absorbing surfaces. To further mitigate debris deposition in the final-focus magnet region, and prevent voltage breakdown, a 'magnetic shutter' has been envisaged to divert the debris out of the final-focus region. This shutter will prevent the hot ablation debris from reaching the magnet region and, coupled to some ionizing scheme, will conveniently suppress early ingression of debris into the final-focus magnet region

Electrohydrodynamic emitters of ion beams

International Nuclear Information System (INIS)

Dudnikov, V.G.; Shabalin, A.L.

1990-01-01

Physical processes determining generation of ion beams with high emission current density in electrohydrodynamic emitters are considered. Electrohydrodynamic effects developing in ion emission features and kinetics of ion interaction in beams with high density are discussed. Factors determining the size of the emission zone, emission stability at high and low currents, cluster generation, increase of energy spread and decrease of brightness are analyzed. Problems on practical provision of stable EHD emitter functioning are considered. 94 refs.; 8 figs.; 1 tab

Nonlinear waves in electron–positron–ion plasmas including charge ...

Indian Academy of Sciences (India)

The effects of the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle are investigated. It is shown that depending on the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle, the numerical solutions exhibit waveforms that are ...

Normal foot and ankle

International Nuclear Information System (INIS)

Weissman, S.D.

1989-01-01

The foot may be thought of as a bag of bones tied tightly together and functioning as a unit. The bones re expected to maintain their alignment without causing symptomatology to the patient. The author discusses a normal radiograph. The bones must have normal shape and normal alignment. The density of the soft tissues should be normal and there should be no fractures, tumors, or foreign bodies

Exchange-correlation energies of atoms from efficient density functionals: influence of the electron density

Science.gov (United States)

Tao, Jianmin; Ye, Lin-Hui; Duan, Yuhua

2017-12-01

The primary goal of Kohn-Sham density functional theory is to evaluate the exchange-correlation contribution to electronic properties. However, the accuracy of a density functional can be affected by the electron density. Here we apply the nonempirical Tao-Mo (TM) semilocal functional to study the influence of the electron density on the exchange and correlation energies of atoms and ions, and compare the results with the commonly used nonempirical semilocal functionals local spin-density approximation (LSDA), Perdew-Burke-Ernzerhof (PBE), Tao-Perdew-Staroverov-Scuseria (TPSS), and hybrid functional PBE0. We find that the spin-restricted Hartree-Fock density yields the exchange and correlation energies in good agreement with the Optimized Effective Potential method, particularly for spherical atoms and ions. However, the errors of these semilocal and hybrid functionals become larger for self-consistent densities. We further find that the quality of the electron density have greater effect on the exchange-correlation energies of kinetic energy density-dependent meta-GGA functionals TPSS and TM than on those of the LSDA and GGA, and therefore, should have greater influence on the performance of meta-GGA functionals. Finally, we show that the influence of the density quality on PBE0 is slightly reduced, compared to that of PBE, due to the exact mixing.

Particle densities in a positive column He-I+ discharge

International Nuclear Information System (INIS)

Gato, T.

1980-01-01

In a positive column He-1 + laser discharge, the He + ion density has been determined directly from the absorption of the HeII 30.3 nm resonance line measured by a modified absorption method, and the electron density has been obtained using this measured He + ion density. The population densities of the upper and lower states of the 612.7 nm laser line have also been measured roughly. (orig.)

Identification of Raman peaks of high-T{sub c} cuprates in normal state through density of states

Energy Technology Data Exchange (ETDEWEB)

Bishoyi, K.C. [P.G. Department of Physics, F.M. College (Auto.), Balasore 756 001 (India)]. E-mail: bishoyi@iopb.res.in; Rout, G.C. [Condensed Matter Physics Group, Govt. Science College, Chatrapur 761 020, Orissa (India); Behera, S.N. [Physics Enclave, H.I.G.-23/1, Housing Board Phase-I, Chandrasekharpur, Bhubaneswar 7510016 (India)

2007-05-31

We present a microscopic theory to explain and identify the Raman spectral peaks of high-T{sub c} cuprates R{sub 2-x}M{sub x}CuO{sub 4} in the normal state. We used electronic Hamiltonian prescribed by Fulde in presence of anti-ferromagnetism. Phonon interaction to the hybridization between the conduction electrons of the system and the f-electrons has been incorporated in the calculation. The phonon spectral density is calculated by the Green's function technique of Zubarev at zero wave vector and finite (room) temperature limit. The four Raman active peaks (P{sub 1}-P{sub 4}) representing the electronic states of the atomic sub-systems of the cuprate system are identified by the calculated quasi-particle energy bands and electron density of states (DOS). The effect of interactions on these peaks are also explained.

Condensation energy density in Bi-2212 superconductors

International Nuclear Information System (INIS)

Matsushita, Teruo; Kiuchi, Masaru; Haraguchi, Teruhisa; Imada, Takeki; Okamura, Kazunori; Okayasu, Satoru; Uchida, Satoshi; Shimoyama, Jun-ichi; Kishio, Kohji

2006-01-01

The relationship between the condensation energy density and the anisotropy parameter, γ a , has been derived for Bi-2212 superconductors in various anisotropic states by analysing the critical current density due to columnar defects introduced by heavy ion irradiation. The critical current density depended on the size of the defects, determined by the kind and irradiation energy of the ions. A significantly large critical current density of 17.0 MA cm -2 was obtained at 5 K and 0.1 T even for the defect density of a matching field of 1 T in a specimen irradiated with iodine ions. The dependence of the critical current density on the size of the defects agreed well with the prediction from the summation theory of pinning forces, and the condensation energy density could be obtained consistently from specimens irradiated with different ions. The condensation energy density obtained increased with decreasing γ a over the entire range of measurement temperature, and reached about 60% of the value for the most three-dimensional Y-123 observed by Civale et al at 5 K. This gives the reason for the very strong pinning in Bi-2212 superconductors at low temperatures. The thermodynamic critical field obtained decreased linearly with increasing temperature and extrapolated to zero at a certain characteristic temperature, T * , lower than the critical temperature, T c . T * , which seems to be associated with the superconductivity in the block layers, was highest for the optimally doped specimen. This shows that the superconductivity becomes more inhomogeneous as the doped state of a superconductor deviates from the optimum condition

Ion beam deposition system for depositing low defect density extreme ultraviolet mask blanks

Science.gov (United States)

Jindal, V.; Kearney, P.; Sohn, J.; Harris-Jones, J.; John, A.; Godwin, M.; Antohe, A.; Teki, R.; Ma, A.; Goodwin, F.; Weaver, A.; Teora, P.

2012-03-01

Extreme ultraviolet lithography (EUVL) is the leading next-generation lithography (NGL) technology to succeed optical lithography at the 22 nm node and beyond. EUVL requires a low defect density reflective mask blank, which is considered to be one of the top two critical technology gaps for commercialization of the technology. At the SEMATECH Mask Blank Development Center (MBDC), research on defect reduction in EUV mask blanks is being pursued using the Veeco Nexus deposition tool. The defect performance of this tool is one of the factors limiting the availability of defect-free EUVL mask blanks. SEMATECH identified the key components in the ion beam deposition system that is currently impeding the reduction of defect density and the yield of EUV mask blanks. SEMATECH's current research is focused on in-house tool components to reduce their contributions to mask blank defects. SEMATECH is also working closely with the supplier to incorporate this learning into a next-generation deposition tool. This paper will describe requirements for the next-generation tool that are essential to realize low defect density EUV mask blanks. The goal of our work is to enable model-based predictions of defect performance and defect improvement for targeted process improvement and component learning to feed into the new deposition tool design. This paper will also highlight the defect reduction resulting from process improvements and the restrictions inherent in the current tool geometry and components that are an impediment to meeting HVM quality EUV mask blanks will be outlined.

Plasma diagnostic tools for optimizing negative hydrogen ion sources

International Nuclear Information System (INIS)

Fantz, U.; Falter, H.D.; Franzen, P.; Speth, E.; Hemsworth, R.; Boilson, D.; Krylov, A.

2006-01-01

The powerful diagnostic tool of optical emission spectroscopy is used to measure the plasma parameters in negative hydrogen ion sources based on the surface mechanism. Results for electron temperature, electron density, atomic-to-molecular hydrogen density ratio, and gas temperature are presented for two types of sources, a rf source and an arc source, which are currently under development for a neutral beam heating system of ITER. The amount of cesium in the plasma volume is obtained from cesium radiation: the Cs neutral density is five to ten orders of magnitude lower than the hydrogen density and the Cs ion density is two to three orders of magnitude lower than the electron density in front of the grid. It is shown that monitoring of cesium lines is very useful for monitoring the cesium balance in the source. From a line-ratio method negative ion densities are determined. In a well-conditioned source the negative ion density is of the same order of magnitude as the electron density and correlates with extracted current densities

Dopant density from maximum-minimum capacitance ratio of implanted MOS structures

International Nuclear Information System (INIS)

Brews, J.R.

1982-01-01

For uniformly doped structures, the ratio of the maximum to the minimum high frequency capacitance determines the dopant ion density per unit volume. Here it is shown that for implanted structures this 'max-min' dopant density estimate depends upon the dose and depth of the implant through the first moment of the depleted portion of the implant. A a result, the 'max-min' estimate of dopant ion density reflects neither the surface dopant density nor the average of the dopant density over the depletion layer. In particular, it is not clear how this dopant ion density estimate is related to the flatband capacitance. (author)

Gas discharge ion source. I. Duoplasmatron

International Nuclear Information System (INIS)

Bacon, F.M.

1978-01-01

The effects of the plasma expansion cup on the operation of a duoplasmatron ion source have been investigated by measuring the total ion current and the distributions of the ion energy, mass, and current density. A copper expansion cup did not affect the magnetic field near the anode of the ion source and consequently the ion current density distribution was sharply peaked near the center of the cup. Ion energy distributions were approximately symmetrical about anode potential. The dominant ionic species were D + 3 and D + at low and high arc currents, respectively. Changes in the electrical potential of the copper cup with respect to the anode produced negligible changes in the above data. A mild steel plasma expansion cup caused the magnetic field to diverge and intercept the cup walls, resulting in ion current density distributions that were flatter and more amenable to focusing than the ones with the copper cup. With the steel cup at anode potential, the ion mass distribution was similar to that from the copper cup; however, the ion energy distribution was asymmetrical about the anode potential with a peak about 10-20 V above anode potential. The total ion current from this mode of operation was about one-third the value from the copper cup. If the steel cup assumed floating potential, about 50 V below anode potential, the total current increased to the level observed from the copper cup and the ion energy distribution was similar to that observed with the copper cup but the current density distribution was much flatter than that of the copper cup. The ion mass distribution was 60%-70% atomic ions over the entire arc current range investigated. Based on these data, a modified plasma expansion cup was designed with tapered steel walls lined with a boron nitride insert. The overall performance of the duoplasmatron ion source with this cup was superior to any of the previous three modes of operation

The deduction of low-Z ion temperature and densities in the JET tokamak using charge exchange recombination spectroscopy

International Nuclear Information System (INIS)

Boileau, A.; Hellermann, M. von; Horton, L.D.; Spence, J.; Summers, H.P.

1989-01-01

A charge exchange recombination spectroscopy (CXRS) diagnostic has been established on JET to study fully stripped low-Z species. Ion temperature in the plasma centre is measured from visible lines of helium, carbon and oxygen excited by charge exchange with heating neutral beam particles. Coincident cold components produced at the plasma edge are apparent on helium and carbon spectra and most spectra are subject to accidental blending from other species' edge plasma emission. The charge exchange feature can be isolated from the various composite lines and all three impurities agree on the same temperature within experimental error. Observed column emissivities are converted into absolute impurity densities using a neutral beam attenuation code and charge exchange effective rate coefficients. Comprehensive new calculations have been performed to obtain the effective rate coefficients. The models take detailed account of cascading and the influence of the plasma environment in causing l-mixing, and allow the n-dependence of the rate coefficients to be addressed experimentally. The effective ion charge reconstructed from simultaneous measurements of the densities of dominant impurities shows good agreement with the value inferred from visible Bremsstrahlung. Some illustrative results are shown for helium (helium discharge or minority r.f.. heating), carbon and oxygen concentrations monitored during characteristic operating regimes. (author)

Numerical simulation of ion temperature gradient driven modes in the presence of ion-ion collisions

International Nuclear Information System (INIS)

Xu, X.Q.

1990-08-01

Ion temperature gradient driven modes in the presence of ion-ion collisions in a toroidal geometry with trapped ions have been studied by using a 1 2/2 d linearized gyro-kinetic particle simulation code in the electrostatic limit. The purpose of the investigation is to try to understand the physics of flat density discharges, in order to test the marginal stability hypothesis. Results giving threshold conditions of L Ti /R 0 , an upper bound on k χ , and linear growth rates and mode frequencies over all wavelengths for the collisionless ion temperature gradient driven modes are obtained. The behavior of ion temperature gradient driven instabilities in the transition from slab to toroidal geometry, with trapped ions, is shown. A Monte Carlo scheme for the inclusion of ion-ion collisions, in which ions can undergo Coulomb collisional dynamical friction, velocity space diffusion and random walk of guiding centers, has been constructed. The effects of ion-ion collisions on the long wave length limit of the ion modes is discussed. 44 refs., 12 figs

SM-1 negative ion source

International Nuclear Information System (INIS)

Huang Zhenjun; Wang Jianzhen

1987-01-01

The working principle and characteristics of SM-1 Negative Ion Source is mainly introduced. In the instrument, there is a device to remove O 3 . This instrument can keep high density of negative ions which is generated by the electrical coronas setting out electricity at negative high voltage and can remove the O 3 component which is harmful to the human body. The density of negative ions is higher than 2.5 x 10 6 p./cm 3 while that of O 3 components is less than 1 ppb at the distance of 50 cm from the panel of the instrument. The instrument sprays negative ions automatically without the help of electric fan, so it works noiselessly. It is widely used in national defence, industry, agriculture, forestry, stock raising, sidelines and in the places with an equipment of low density of negative ion or high concentration of O 3 components. Besides, the instrument may also be used to treat diseases, to prevent against rot, to arrest bacteria, to purify air and so on

The gridless plasma ion source (GIS) for plasma ion assisted optical coating

International Nuclear Information System (INIS)

You Dawei; Li Xiaoqian; Wang Yu; Lin Yongchang

2004-01-01

High-quality optical coating is a key technology for modern optics. Ion-assisted deposition technology was used to improve the vaporized coating in 1980's. The GIS (gridless ion source), which is an advanced plasma source for producing a high-quality optical coating in large area, can produce a large area uniformity>1000 mm (diameter), a high ion current density ∼0.5 mA/cm 2 , 20 eV-200 eV energetic plasma ions and can activate reactive gas and film atoms. Now we have developed a GIS system. The GIS and the plasma ion-assisted deposition technology are investigated to achieve a high-quality optical coating. The GIS is a high power and high current source with a power of 1 kW-7.5 kW, a current of 10 A- 70 A and an ion density of 200 μA/cm 2 -500 μA/cm 2 . Because of the special magnetic structure, the plasma-ion extraction efficiency has been improved to obtain a maximum ion density of 500 μA/cm 2 in the medium power (∼4 kW) level. The GIS applied is of a special cathode structure, so that the GIS operation can be maintained under a rather low power and the lifetime of cathode will be extended. The GIS has been installed in the LPSX-1200 type box coating system. The coated TiO 2 , SiO 2 films such as antireflective films with the system have the same performance reported by Leybold Co, 1992, along with a controllable refractive index and film structure. (authors)

Source of the backstreaming ion beams in the foreshock region

International Nuclear Information System (INIS)

Tanaka, M.; Goodrich, C.C.; Winske, D.; Papadopoulos, K.

1983-01-01

A new source mechanism is proposed for the 'reflected' ion beams observed in the foreshock region of the earth's bow shock. In our model the beams originate in the magnetosheath downstream of the qausi-perpendicular portion of the shock. The quasi-perpendicular shock transition is characterized by two downstream ion populations including high-energy gyrating ions in addition to the directly transmitted anisotropic ions. We show by particle simulations that this highly anisotropic downstream ion distribution (T/sub perpendicular//T/sub parallel/ >>1) can excite electromagnetic ion cyclotron waves which, in turn, pitch angle scatter the gyrating ions in a few ion gyroperiods. As a result, some ions acquire large parallel velocities and move fast enough along the convecting downstream magnetic field to escape back across the bow shock into the upstream region. The distribution of escaping ions calculated by using the pitch-angle-scattered ions, as a source, becomes a beam with a large temperature anisotropy T/sub perpendicular/ approx.3--5 T/sub parallel/ and a mean velocity along the magnetic field of about twice that of the solar wind velocity. A significant result is the presence of the maximum angle theta/sub n/B = theta/sub c/ above which no ions can escape, where theta/sub n/B is the angle between the shock normal and the interplanetary magnetic field. A wide peak of constant escaping ion flux is formed below theta/sub c/ whose number density is 1--2% of that of the solar wind. These results are in general agreement with the ISEE observations of the 'reflected' ions

Semi-analytical quasi-normal mode theory for the local density of states in coupled photonic crystal cavity-waveguide structures

DEFF Research Database (Denmark)

de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst; Mørk, Jesper

2015-01-01

We present and validate a semi-analytical quasi-normal mode (QNM) theory for the local density of states (LDOS) in coupled photonic crystal (PhC) cavity-waveguide structures. By means of an expansion of the Green's function on one or a few QNMs, a closed-form expression for the LDOS is obtained, ......-trivial spectrum with a peak and a dip is found, which is reproduced only when including both the two relevant QNMs in the theory. In both cases, we find relative errors below 1% in the bandwidth of interest.......We present and validate a semi-analytical quasi-normal mode (QNM) theory for the local density of states (LDOS) in coupled photonic crystal (PhC) cavity-waveguide structures. By means of an expansion of the Green's function on one or a few QNMs, a closed-form expression for the LDOS is obtained......, and for two types of two-dimensional PhCs, with one and two cavities side-coupled to an extended waveguide, the theory is validated against numerically exact computations. For the single cavity, a slightly asymmetric spectrum is found, which the QNM theory reproduces, and for two cavities a non...

Space and time resolved spectroscopy of laser-produced plasmas: A study of density-sensitive x-ray transitions in helium-like and neon-like ions

Energy Technology Data Exchange (ETDEWEB)

Young, Bruce Kai Fong

1988-09-01

The determination of level populations and detailed population mechanisms in dense plasmas has become an increasingly important problem in atomic physics. In this work, the density variation of line intensities and level populations in aluminum K-shell and molybdenum and silver L-shell emission spectra have been measured from high-powered, laser-produced plasmas. For each case, the density dependence of the observed line emission is due to the effect of high frequency electron-ion collisions on metastable levels. The density dependent line intensities vary greatly in laser-produced plasmas and can be used to extract detailed information concerning the population kinetics and level populations of the ions. The laser-plasmas had to be fully characterized in order to clearly compare the observed density dependence with atomic theory predictions. This has been achieved through the combined use of new diagnostic instruments and microdot targets which provided simultaneously space, time, and spectrally resolved data. The plasma temperatures were determined from the slope of the hydrogen-like recombination continuum. The time resolved electron density profiles were measured using multiple frame holographic interferometry. Thus, the density dependence of K-shell spectral lines could be clearly examined, independent of assumptions concerning the dynamics of the plasma. In aluminum, the electron density dependence of various helium-like line intensity ratios were measured. Standard collisional radiative equilibrium models fail to account for the observed density dependence measured for the ''He/sub ..cap alpha..//IC'' ratio. Instead, a quasi-steady state atomic model based on a purely recombining plasma is shown to accurately predict the measured density dependence. This same recombining plasma calculation successfully models the density dependence of the high-n ''He/sub ..gamma..//He/sub ..beta../'' and ''He/sub delta

Space and time resolved spectroscopy of laser-produced plasmas: A study of density-sensitive x-ray transitions in helium-like and neon-like ions

International Nuclear Information System (INIS)

Young, Bruce Kai Fong.

1988-09-01

The determination of level populations and detailed population mechanisms in dense plasmas has become an increasingly important problem in atomic physics. In this work, the density variation of line intensities and level populations in aluminum K-shell and molybdenum and silver L-shell emission spectra have been measured from high-powered, laser-produced plasmas. For each case, the density dependence of the observed line emission is due to the effect of high frequency electron-ion collisions on metastable levels. The density dependent line intensities vary greatly in laser-produced plasmas and can be used to extract detailed information concerning the population kinetics and level populations of the ions. The laser-plasmas had to be fully characterized in order to clearly compare the observed density dependence with atomic theory predictions. This has been achieved through the combined use of new diagnostic instruments and microdot targets which provided simultaneously space, time, and spectrally resolved data. The plasma temperatures were determined from the slope of the hydrogen-like recombination continuum. The time resolved electron density profiles were measured using multiple frame holographic interferometry. Thus, the density dependence of K-shell spectral lines could be clearly examined, independent of assumptions concerning the dynamics of the plasma. In aluminum, the electron density dependence of various helium-like line intensity ratios were measured. Standard collisional radiative equilibrium models fail to account for the observed density dependence measured for the ''He/sub α//IC'' ratio. Instead, a quasi-steady state atomic model based on a purely recombining plasma is shown to accurately predict the measured density dependence. This same recombining plasma calculation successfully models the density dependence of the high-n ''He/sub γ//He/sub β/'' and ''He/sub δ//He/sub β/'' helium-like resonance line intensity ratios

Positive ion mobilities in normal liquid 3He at ultralow temperatures

International Nuclear Information System (INIS)

Alexander, P.W.

1978-11-01

The mobility has been measured of positive ions in liquid 3 he in the range 2.5 mK 3 sub(m)/sup(V) 5 sub(m)/sup(V). The effects of 500 p.p.m. 4 He in the 3 He were investigated. It was found that, at low temperatures, several stable ion species could be produced for 3 He pressures of 23 bar and above and, between 25 mK and 60 mK, time dependent conversion from one species of ion to another was observed at all pressures. The creation mechanism, mobility and stability of multiple positive ions were studied. Possible explanations of the phenomena are discussed. The measured drift field dependence of mobility is used to test the quasiparticle scattering model assumed for the liquid. (U.K.)

High-Energy-Density Aqueous Magnesium-Ion Battery Based on a Carbon-Coated FeVO4 Anode and a Mg-OMS-1 Cathode.

Science.gov (United States)

Zhang, Hongyu; Ye, Ke; Zhu, Kai; Cang, Ruibai; Yan, Jun; Cheng, Kui; Wang, Guiling; Cao, Dianxue

2017-12-01

Porous FeVO 4 is prepared by hydrothermal method and further modified by coating with carbon to obtain FeVO 4 /C with a hierarchical pore structure. FeVO 4 /C is used as an anodic electrode in aqueous rechargeable magnesium-ion batteries. The FeVO 4 /C material not only has improved electrical conductivity as a result of the carbon coating layer, but also has an increased specific surface area as a result of the hierarchical pore structure, which is beneficial for magnesium-ion insertion/deinsertion. Therefore, an aqueous rechargeable magnesium-ion full battery is successfully constructed with FeVO 4 /C as the anode, Mg-OMS-1 (OMS=octahedral molecular sieves) as the cathode, and 1.0 mol L -1 MgSO 4 as the electrolyte. The discharge capacity of the Mg-OMS-1//FeVO 4 /C aqueous battery is 58.9 mAh g -1 at a current density of 100 mA g -1 ; this value is obtained by calculating the total mass of two electrodes and the capacity retention rate of this device is 97.7 % after 100 cycles, with almost 100 % coulombic efficiency, which indicates that the system has a good electrochemical reversibility. Additionally, this system can achieve a high energy density of 70.4 Wh kg -1 , which provides powerful evidence that an aqueous magnesium-ion battery is possible. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Upgraded millimeter-wave interferometer for measuring the electron density during the beam extraction in the negative ion source

Energy Technology Data Exchange (ETDEWEB)

Tokuzawa, T., E-mail: tokuzawa@nifs.ac.jp; Kisaki, M.; Nagaoka, K.; Ito, Y.; Ikeda, K.; Nakano, H. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Tsumori, K.; Osakabe, M.; Takeiri, Y. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); The Graduate University for Advanced Studies, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Kaneko, O. [National Institutes of Natural Sciences, 4-3-13 Toranomon, Minato-ku, Tokyo 105-0001 (Japan)

2016-11-15

The upgraded millimeter-wave interferometer with the frequency of 70 GHz is installed on a large-scaled negative ion source. Measurable line-averaged electron density is from 2 × 10{sup 15} to 3 × 10{sup 18} m{sup −3} in front of the plasma grid. Several improvements such as the change to shorter wavelength probing with low noise, the installation of special ordered horn antenna, the signal modulation for a high accuracy digital phase detection, the insertion of insulator, and so on, are carried out for the measurement during the beam extraction by applying high voltage. The line-averaged electron density is successfully measured and it is found that it increases linearly with the arc power and drops suddenly at the beam extraction.

Normal lumbar spine bone mineral densities with single-energy CT

International Nuclear Information System (INIS)

Hendrick, R.E.; Ritenour, E.R.; Geis, J.R.; Thickman, D.; Freeman, K.

1988-01-01

The authors report trabecular spine densities determined by single-energy CT in 267 healthy women, aged 22 to 75 years. Volunteers were scanned at eight sites with use of identical fourth-generation CT scanners, postpatient calibration phantoms, and analysis software that accounts for beam hardening as a function of patient size. Results indicate that a cubic polynomial best represents the decrease in bone density (in milligrams per milliliter of K 2 HPO 4 ) with age (in years): Bone Density = 140.9 + 4.44(Age) - 0.133(Age) 2 + 0.0008(Age) 3 , with statistical significance over the best linear and quadratic polynomial fits (P < .001). The mean bone densities of healthy women above age 30 years are found to be lower by an average of 8 mg/mL than reported by Cann et al, whose data indicate that the greatest loss in trabecular bone density in healthy women occurs in the 50-59-year group, while out data indicate greatest loss in the 60-75 year age group

Heavy-ion mammography and breast cancer

International Nuclear Information System (INIS)

Fabrikant, J.I.; Tobias, C.A.; Capp, M.P.; Holley, W.R.; Woodruff, K.H.; Sickles, E.A.

1980-01-01

Heavy-ion radiography is a new diagnostic imaging technique developed in our laboratory that produces superior density resolution at low radiation doses. Heavy-ion mammography has now emerged as a low-dose, safe, reliable, noninvasive diagnostic radiological procedure that can quantitate and image very small differences in soft tissue densities in the breast tissues of patients with clinical breast disease. The improved density resolution of heavy-ion mammography over conventional X-ray mammography and breast xerography provides the potential of detecting small breast cancers of less than 1 cm diameter. The radiation dose to the breast from carbon-ion mammorgraphy is about 50 mrad or less, and can potentially be only a fraction of this level. The results of the present clinical trial in progress of heavy-ion mammography in 37 patients, thus far studied, are extremely encouraging, and warrant continued study for application to the early diagnosis of breast cancer in women

Origin of stabilization and destabilization in solid-state redox reaction of oxide ions for lithium-ion batteries.

Science.gov (United States)

Yabuuchi, Naoaki; Nakayama, Masanobu; Takeuchi, Mitsue; Komaba, Shinichi; Hashimoto, Yu; Mukai, Takahiro; Shiiba, Hiromasa; Sato, Kei; Kobayashi, Yuki; Nakao, Aiko; Yonemura, Masao; Yamanaka, Keisuke; Mitsuhara, Kei; Ohta, Toshiaki

2016-12-23

Further increase in energy density of lithium batteries is needed for zero emission vehicles. However, energy density is restricted by unavoidable theoretical limits for positive electrodes used in commercial applications. One possibility towards energy densities exceeding these limits is to utilize anion (oxide ion) redox, instead of classical transition metal redox. Nevertheless, origin of activation of the oxide ion and its stabilization mechanism are not fully understood. Here we demonstrate that the suppression of formation of superoxide-like species on lithium extraction results in reversible redox for oxide ions, which is stabilized by the presence of relatively less covalent character of Mn 4+ with oxide ions without the sacrifice of electronic conductivity. On the basis of these findings, we report an electrode material, whose metallic constituents consist only of 3d transition metal elements. The material delivers a reversible capacity of 300 mAh g -1 based on solid-state redox reaction of oxide ions.

Origin of stabilization and destabilization in solid-state redox reaction of oxide ions for lithium-ion batteries

Science.gov (United States)

Yabuuchi, Naoaki; Nakayama, Masanobu; Takeuchi, Mitsue; Komaba, Shinichi; Hashimoto, Yu; Mukai, Takahiro; Shiiba, Hiromasa; Sato, Kei; Kobayashi, Yuki; Nakao, Aiko; Yonemura, Masao; Yamanaka, Keisuke; Mitsuhara, Kei; Ohta, Toshiaki

2016-01-01

Further increase in energy density of lithium batteries is needed for zero emission vehicles. However, energy density is restricted by unavoidable theoretical limits for positive electrodes used in commercial applications. One possibility towards energy densities exceeding these limits is to utilize anion (oxide ion) redox, instead of classical transition metal redox. Nevertheless, origin of activation of the oxide ion and its stabilization mechanism are not fully understood. Here we demonstrate that the suppression of formation of superoxide-like species on lithium extraction results in reversible redox for oxide ions, which is stabilized by the presence of relatively less covalent character of Mn4+ with oxide ions without the sacrifice of electronic conductivity. On the basis of these findings, we report an electrode material, whose metallic constituents consist only of 3d transition metal elements. The material delivers a reversible capacity of 300 mAh g−1 based on solid-state redox reaction of oxide ions. PMID:28008955

Plasma rest frame distributions of suprathermal ions in the earth's foreshock region

International Nuclear Information System (INIS)

Sentman, D.D.; Kennel, C.F.; Frank, L.A.

1981-01-01

We present rest frame ion distributions computed from three-dimensional observations of upstream superthermal ions gained by the Universtiy of Iowa Quadrispherical Lepedea on ISEE-1. The observations are for a single inbound, midmorning pass starting upstream from the ion foreshock and continuing across the quasiparallel bow shock into the magnetosheath. The crossing of the ion foreshock boundary is marked by a several minute burst of ions of temperature 100--200 eV moving along the IMF away from the bow shock at 500 km/s relative to the solar wind. The observation of these 'reflected' ions is followed by an extended interval of 'diffuse' ions of temperatures 2--3 keV flowing at approx.250 km/s relative to the solar wind and persisting until the bow shock is crossed. The diffuse ion β has a value of approximately 6 in the region of the superthermal ions, exceeding the normal thermal β of the solar wind by roughly an order of magnitude. Both types of superthermal ions constitute roughly 2% of the total ion density and carry a parallel heat flux of approx.2 x 10 -2 ergs cm -2 s -2 . When integrated over an assumed 10 x 10 R/sub E/ bow shock emission area, this implies an upstream dissipation that may approach 10 17 to 10 18 ergs/s, comparable to a modest substorm

Thirty-centimeter-diameter ion milling source

International Nuclear Information System (INIS)

Robinson, R.S.

1978-01-01

A 30 cm beam diameter ion source has been designed and fabricated for micromachining and sputtering applications. An argon ion current density of 1 mA/cm 2 at 500 eV ion energy was selected as a design operating condition. The completed ion source met the design criteria at this operating condition with a uniform and well-collimated beam having an average variation in current density of +- 5% over the center of 20 cm of the beam. This ion source has a multipole magnetic field that employs permanent magnets between permeable pole pieces. Langmuir probe surveys of the source plasma support the design concepts of a multipole field and a circumferential cathode to enhance plasma uniformity

Fully nonlinear ion-acoustic solitary waves in a plasma with positive-negative ions and nonthermal electrons

International Nuclear Information System (INIS)

Sabry, R.; Shukla, P. K.; Moslem, W. M.

2009-01-01

Properties of fully nonlinear ion-acoustic solitary waves in a plasma with positive-negative ions and nonthermal electrons are investigated. For this purpose, the hydrodynamic equations for the positive-negative ions, nonthermal electron density distribution, and the Poisson equation are used to derive the energy integral equation with a new Sagdeev potential. The latter is analyzed to examine the existence regions of the solitary pulses. It is found that the solitary excitations strongly depend on the mass and density ratios of the positive and negative ions as well as the nonthermal electron parameter. Numerical solution of the energy integral equation clears that both positive and negative potentials exist together. It is found that faster solitary pulses are taller and narrower. Furthermore, increasing the electron nonthermality parameter (negative-to-positive ions density ratio) decreases (increases) the localized excitation amplitude but increases (decreases) the pulse width. The present model is used to investigate the solitary excitations in the (H + ,O 2 - ) and (H + ,H - ) plasmas, where they are presented in the D- and F-regions of the Earth's ionosphere. This investigation should be helpful in understanding the salient features of the fully nonlinear ion-acoustic solitary waves in space and in laboratory plasmas where two distinct groups of ions and non-Boltzmann distributed electrons are present.

Microwave frequency sweep interferometer for plasma density measurements in ECR ion sources: Design and preliminary results

Energy Technology Data Exchange (ETDEWEB)

Torrisi, Giuseppe [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); University Mediterranea of Reggio Calabria, Reggio Calabria (Italy); Mascali, David; Neri, Lorenzo; Leonardi, Ornella; Celona, Luigi; Castro, Giuseppe; Agnello, Riccardo; Caruso, Antonio; Passarello, Santi; Longhitano, Alberto; Gammino, Santo [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); Sorbello, Gino [INFN - Laboratori Nazionali del Sud, Via S. Sofia 62, 95125 Catania (Italy); University of Catania, Catania, Italy and INFN-LNS, Catania (Italy); Isernia, Tommaso [University Mediterranea of Reggio Calabria, Reggio Calabria (Italy)

2016-02-15

The Electron Cyclotron Resonance Ion Sources (ECRISs) development is strictly related to the availability of new diagnostic tools, as the existing ones are not adequate to such compact machines and to their plasma characteristics. Microwave interferometry is a non-invasive method for plasma diagnostics and represents the best candidate for plasma density measurement in hostile environment. Interferometry in ECRISs is a challenging task mainly due to their compact size. The typical density of ECR plasmas is in the range 10{sup 11}–10{sup 13} cm{sup −3} and it needs a probing beam wavelength of the order of few centimetres, comparable to the chamber radius. The paper describes the design of a microwave interferometer developed at the LNS-INFN laboratories based on the so-called “frequency sweep” method to filter out the multipath contribution in the detected signals. The measurement technique and the preliminary results (calibration) obtained during the experimental tests will be presented.

Temperature dependent surface modification of molybdenum due to low energy He+ ion irradiation

International Nuclear Information System (INIS)

Tripathi, J.K.; Novakowski, T.J.; Joseph, G.; Linke, J.; Hassanein, A.

2015-01-01

In this paper, we report on the temperature dependent surface modifications in molybdenum (Mo) samples due to 100 eV He + ion irradiation in extreme conditions as a potential candidate to plasma-facing components in fusion devices alternative to tungsten. The Mo samples were irradiated at normal incidence, using an ion fluence of 2.6 × 10 24 ions m −2 (with a flux of 7.2 × 10 20 ions m −2 s −1 ). Surface modifications have been studied using high-resolution field emission scanning electron-(SEM) and atomic force (AFM) microscopy. At 773 K target temperature homogeneous evolution of molybdenum nanograins on the entire Mo surface were observed. However, at 823 K target temperature appearance of nano-pores and pin-holes nearby the grain boundaries, and Mo fuzz in patches were observed. The fuzz density increases significantly with target temperatures and continued until 973 K. However, at target temperatures beyond 973 K, counterintuitively, a sequential reduction in the fuzz density has been seen till 1073 K temperatures. At 1173 K and above temperatures, only molybdenum nano structures were observed. Our temperature dependent studies confirm a clear temperature widow, 823–1073 K, for Mo fuzz formation. Ex-situ high resolution X-ray photoelectron spectroscopy studies on Mo fuzzy samples show the evidence of MoO 3 3d doublets. This elucidates that almost all the Mo fuzz were oxidized during open air exposure and are thick enough as well. Likewise the microscopy studies, the optical reflectivity measurements also show a sequential reduction in the reflectivity values (i.e., enhancement in the fuzz density) up to 973 K and after then a sequential enhancement in the reflectivity values (i.e., reduction in the fuzz density) with target temperatures. This is in well agreement with microscopy studies where we observed clear temperature window for Mo fuzz growth

Bremsstrahlung spectra for Al, Cs, and Au atoms in high-temperature, high-density plasmas

International Nuclear Information System (INIS)

Kim, L.; Pratt, R.H.; Tseng, H.K.

1985-01-01

Results are presented from a numerical calculation for the bremsstrahlung spectrum and Gaunt factors of Al, Cs, and Au atoms in high-temperature (-T), high-density (-rho) plasmas. Plasma temperatures kT = 0.1 and 1.0 keV and plasma densities rho = rho 0 (the normal solid density) and rho = 100rho 0 are considered. This allows us to determine the generality and identify the origins of features which we had previously identified in calculations for Cs. We also now present results for the total energy loss of an electron in such a plasma. We use a relativistic multipole code which treats the bremsstrahlung process as a single-electron transition in a static screened central potential. We take for the static potential corresponding to an atom in a hot dense plasma the finite-temperature, finite-density Thomas-Fermi model. This approach corresponds to an average atom in local thermodynamic equilibrium. In comparison to isolated-neutral-atom results we observe general suppression of cross sections and a particular suppression in the tip region of the spectrum. Within this model, both superscreening and shape resonances are found in the circumstances of extreme density. At more normal densities and except for the soft-photon end, the spectrum at these energies for an atom in a hot plasma (characterized by an average degree of ionization) can be well represented by the spectrum of the corresponding isolated ion, which has a similar potential shape at the distances which characterize the process

Effect of EMIC Wave Normal Angle Distribution on Relativistic Electron Scattering Based on the Newly Developed Self-consistent RC/EMIC Waves Model by Khazanov et al. [2006

Science.gov (United States)

Khazanov, G. V.; Gallagher, D. L.; Gamayunov, K.

2007-01-01

It is well known that the effects of EMIC waves on RC ion and RB electron dynamics strongly depend on such particle/wave characteristics as the phase-space distribution function, frequency, wave-normal angle, wave energy, and the form of wave spectral energy density. Therefore, realistic characteristics of EMIC waves should be properly determined by modeling the RC-EMIC waves evolution self-consistently. Such a selfconsistent model progressively has been developing by Khaznnov et al. [2002-2006]. It solves a system of two coupled kinetic equations: one equation describes the RC ion dynamics and another equation describes the energy density evolution of EMIC waves. Using this model, we present the effectiveness of relativistic electron scattering and compare our results with previous work in this area of research.

Ion-assisted sputter deposition of molybdenum--silicon multilayers

International Nuclear Information System (INIS)

Vernon, S.P.; Stearns, D.G.; Rosen, R.S.

1993-01-01

X-ray multilayer (ML) structures that are fabricated by the use of magnetron-sputter deposition exhibit a degradation in structural quality as the deposition pressure is increased. The observed change in morphology is attributed to a reduced mobility of surface adsorbed atoms, which inhibits the formation of smooth, continuous layers. The application of a negative substrate bias produces ion bombardment of the growing film surface by sputtering gas ions extracted from the plasma and permits direct control of the energy density supplied to the film surface during thin-film growth. The technique supplements the energy lost to thermalization in high-pressure deposition and permits the fabrication of high-quality ML structures at elevated processing pressures. A threefold improvement in the soft-x-ray normal-incidence reflectance at 130 A results for substrate bias voltages of the order of ∼-150 V for Mo--Si ML's deposited at 10-mTorr Ar

Computer simulation of scattered ion and sputtered species effects in ion beam sputter-deposition of high temperature superconducting thin films

International Nuclear Information System (INIS)

Krauss, A.R.; Auciello, O.

1992-01-01

Ion beam sputter-deposition is a technique currently used by many groups to produce single and multicomponent thin films. This technique provides several advantages over other deposition methods, which include the capability for yielding higher film density, accurate stoichiometry control, and smooth surfaces. However, the relatively high kinetic energies associated with ion beam sputtering also lead to difficulties if the process is not properly controlled. Computer simulations have been performed to determine net deposition rates, as well as the secondary erosion, lattice damage, and gas implantation in the films, associated with primary ions scattered from elemental Y, Ba and Cu targets used to produce high temperature superconducting Y-Ba-Cu-O films. The simulations were performed using the TRIM code for different ion masses and kinetic energies, and different deposition geometries. Results are presented for primary beams of Ar + , Kr + and Xe + incident on Ba and Cu targets at 0 degrees and 45 degrees with respect to the surface normal, with the substrate positioned at 0 degrees and 45 degrees. The calculations indicate that the target composition, mass and kinetic energy of the primary beam, angle of incidence on the target, and position and orientation of the substrate affect the film damage and trapped primary beam gas by up to 5 orders of magnitude

Understanding the apparent diffusivity of Sr-85 ion for MX-80 in different salinity condition at low dry density

International Nuclear Information System (INIS)

Ahmad Hasnulhadi Che Kamaruddin

2012-01-01

The apparent diffusivity of strontium-85 in the compacted MX-80 bentonite under different salinity conditions and dry densities was conducted were studied from the viewpoint of activation energy. Through in-diffusions experiments the effect of salinity on diffusion behavior of Sr-85 ions can also can be explained. As we know, Sr-90 is by product of the fission materials of nuclear wastes and should be manage properly. Sr-85 is radioactive isotope with the same chemical properties of Sr-90. Adsorption affects only non-steady-state diffusion while at the steady state (e.g., a constant concentration gradient between a constant source and a constant sink), there is no net uptake or release by adsorption, so adsorption has no effect on diffusion (Drever, James I., 1997). The changes in the basal spacing of bentonite as a function of salinity are needed to be observed by the X-ray diffraction method to understand the microstructure changes in diffusion pathways for Sr-85 in MX-80 bentonite. As we know, there could be three potential pathways for radionuclide diffusion in solution-saturated, compacted montmorillonite, i.e., pore water, external surfaces and the internal surface (interlayer spaces) of montmorillonite aggregates (Kozaki et al., 2008). So, it is important to understand the diffusion processes in term of apparent diffusivity of Sr-85 ions in different salinity concentration at low dry density of MX-80. Several parameters are needed in explaining the process such as dry density, activation energy, temperature dependence and concentration of the salinity solutions. (author)

Bone mineral density in postmenopausal Mexican-Mestizo women with normal body mass index, overweight, or obesity.

Science.gov (United States)

Méndez, Juan Pablo; Rojano-Mejía, David; Pedraza, Javier; Coral-Vázquez, Ramón Mauricio; Soriano, Ruth; García-García, Eduardo; Aguirre-García, María Del Carmen; Coronel, Agustín; Canto, Patricia

2013-05-01

Obesity and osteoporosis are two important public health problems that greatly impact mortality and morbidity. Several similarities between these complex diseases have been identified. The aim of this study was to analyze if different body mass indexes (BMIs) are associated with variations in bone mineral density (BMD) among postmenopausal Mexican-Mestizo women with normal weight, overweight, or different degrees of obesity. We studied 813 postmenopausal Mexican-Mestizo women. A structured questionnaire for risk factors was applied. Height and weight were used to calculate BMI, whereas BMD in the lumbar spine (LS) and total hip (TH) was measured by dual-energy x-ray absorptiometry. We used ANCOVA to examine the relationship between BMI and BMDs of the LS, TH, and femoral neck (FN), adjusting for confounding factors. Based on World Health Organization criteria, 15.13% of women had normal BMI, 39.11% were overweight, 25.96% had grade 1 obesity, 11.81% had grade 2 obesity, and 7.99% had grade 3 obesity. The higher the BMI, the higher was the BMD at the LS, TH, and FN. The greatest differences in size variations in BMD at these three sites were observed when comparing women with normal BMI versus women with grade 3 obesity. A higher BMI is associated significantly and positively with a higher BMD at the LS, TH, and FN.

Secondary ion mass spectroscopy (SIMS)

International Nuclear Information System (INIS)

Naik, P.K.

1975-01-01

Secondary Ion Mass Spectrometry (SIMS) which is primarily a method for investigating the chemical composition of the uppermost atomic layer of solid surfaces is explained. In this method, the specimen is bombarded with a primary positive ion beam of small current density monolayer. Positive and negative ions sputtered from the specimen are mass analysed to give the surface chemical composition. The analytical system which consists of a primary ion source, a target manipulator and a mass spectrometer housed in an ultrahigh vacuum system is described. This method can also be used for profile measurements in thin films by using higher current densities of the primary ions. Fields of application such as surface reactions, semiconductors, thin films emission processes, chemistry, metallurgy are touched upon. Various aspects of this method such as the sputtering process, instrumentation, and applications are discussed. (K.B.)

The nuclear equation of state in effective relativistic field theories and pion yields in heavy-ion collisions

International Nuclear Information System (INIS)

Schoenhofen, M.; Cubero, M.; Gering, M.; Sambataro, M.; Feldmeier, H.; Noerenberg, W.

1989-06-01

Within the framework of relativistic field theory for nucleons, deltas, scalar and vector mesons, a systematic study of the nuclear equation of state and its relation to pion yields in heavy-ion collisions is presented. Not the compressibility but the effective nucleon mass at normal nuclear density turns out to be the most sensitive parameter. Effects from vaccum fluctuations are well modelled within the mean-field no-sea approximation by self-interaction terms for the scalar meson field. Incomplete thermalization in the fireball may be the reason for the low pion yields observed in heavy-ion collisions. (orig.)

Dynamics of plasma ions motion in ultra-intense laser-excited plasma wakes

International Nuclear Information System (INIS)

Zhou Suyun; Li Jing

2013-01-01

The effects of heavy ions and protons motion in an ultra-intense laser-driven plasma wake are compared by rebuilding a plasma wake model. It is shown that with the same laser and plasma background electron density n 0 , the heavy ions' motion suppresses wake-field resonant excitation less than the protons' motion in their own plasma wake. Though heavy ions obtain more kinetic energy from the plasma wake, its energy density is less than that of the protons due to the ion density being far less than the proton density. As a result, the total energy of heavy ions obtained from the wake-field is far less than that of protons. The dependence of the kinetic energy and the energy density of protons and heavy ions on n 0 is discussed. (paper)

Electron-Ion Dynamics with Time-Dependent Density Functional Theory: Towards Predictive Solar Cell Modeling: Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Maitra, Neepa [Hunter College City University of New York, New York, NY (United States)

2016-07-14

This project investigates the accuracy of currently-used functionals in time-dependent density functional theory, which is today routinely used to predict and design materials and computationally model processes in solar energy conversion. The rigorously-based electron-ion dynamics method developed here sheds light on traditional methods and overcomes challenges those methods have. The fundamental research undertaken here is important for building reliable and practical methods for materials discovery. The ultimate goal is to use these tools for the computational design of new materials for solar cell devices of high efficiency.

External excitation of ion cyclotron drift waves in a two-ion species plasma

International Nuclear Information System (INIS)

Kando, M.; Ikezawa, S.; Sugai, H.

1984-01-01

Ion cyclotron drift waves propagating across a density gradient and a magnetic field have been excited externally in a two-ion species plasma, with its concentration ratio controlled. The measured dispersion relations agree with the theoretical predictions. (author)

Study on possibility of development of a laser multicharged ion source for a heavy ion fusion driver

International Nuclear Information System (INIS)

Barabash, L.Z.; Krechet, K.I.; Lapitskij, Yu.Ya.; Latyshev, S.V.; Shumshurov, A.V.

1983-01-01

The results of studying laser produced plasma ion sources for a heavy ion accelerating-storage complex used as a heavy ion fusion driver are presented. The following parameters were measured on an installation aimed for studying physical characteristics of heavy ion laser plasma for a lead target at laser radiation flux density of approximately 3x10 10 W/cm 2 : scattered ion charge composition, energy spectra and scattering angle distributions, ion currents, absolute number of ions in every charge state, plasma electron temperature. The ion current pulse duration varied from 3x10 -4 s at Z +1 to 2x10 -5 s at Z +10 . The maximum current amplitude of 2 mA corresponded to Z +7 charge. The scattering velocity increased with charge. The total number of ions that could be used for acceleration was approximately 5x10 13 for Z +2 and 5x10 12 for Z +6 per pulse. The ion laser source brightness was 2x10 11 A/cm 2 , the particle phase density was 10 18 (cmxrad) -1

Constraints on the high-density nuclear equation of state from the phenomenology of compact stars and heavy-ion collisions

International Nuclear Information System (INIS)

Klaehn, T.; Blaschke, D.; Typel, S.; Dalen, E. N. E. van; Faessler, A.; Fuchs, C.; Gaitanos, T.; Wolter, H. H.; Grigorian, H.; Ho, A.; Weber, F.; Kolomeitsev, E. E.; Miller, M. C.; Roepke, G.; Truemper, J.; Voskresensky, D. N.

2006-01-01

A new scheme for testing nuclear matter equations of state (EoSs) at high densities using constraints from neutron star (NS) phenomenology and a flow data analysis of heavy-ion collisions is suggested. An acceptable EoS shall not allow the direct Urca process to occur in NSs with masses below 1.5M · , and also shall not contradict flow and kaon production data of heavy-ion collisions. Compact star constraints include the mass measurements of 2.1±0.2M · (1σ level) for PSR J0751+1807 and of 2.0±0.1M · from the innermost stable circular orbit for 4U 1636-536, the baryon mass--gravitational mass relationships from Pulsar B in J0737-3039 and the mass-radius relationships from quasiperiodic brightness oscillations in 4U 0614+09 and from the thermal emission of RX J1856-3754. This scheme is applied to a set of relativistic EoSs which are constrained otherwise from nuclear matter saturation properties. We demonstrate on the given examples that the test scheme due to the quality of the newly emerging astrophysical data leads to useful selection criteria for the high-density behavior of nuclear EoSs

Ion-acoustic Gardner solitons in a four-component nonextensive multi-ion plasma

Energy Technology Data Exchange (ETDEWEB)

Jannat, N., E-mail: nilimajannat74@gmail.com; Ferdousi, M.; Mamun, A. A. [Jahangirnagar University, Department of Physics (Bangladesh)

2016-07-15

The nonlinear propagation of ion-acoustic (IA) solitary waves (SWs) in a four-component non-extensive multi-ion plasma system containing inertial positively charged light ions, negatively charged heavy ions, as well as noninertial nonextensive electrons and positrons has been theoretically investigated. The reductive perturbation method has been employed to derive the nonlinear equations, namely, Korteweg−deVries (KdV), modified KdV (mKdV), and Gardner equations. The basic features (viz. polarity, amplitude, width, etc.) of Gardner solitons are found to exist beyond the KdV limit and these IA Gardner solitons are qualitatively different from the KdV and mKdV solitons. It is observed that the basic features of IA SWs are modified by various plasma parameters (viz. electron and positron nonextensivity, electron number density to ion number density, and electron temperature to positron temperature, etc.) of the considered plasma system. The results obtained from this theoretical investigation may be useful in understanding the basic features of IA SWs propagating in both space and laboratory plasmas.

Ion-acoustic Gardner solitons in a four-component nonextensive multi-ion plasma

International Nuclear Information System (INIS)

Jannat, N.; Ferdousi, M.; Mamun, A. A.

2016-01-01

The nonlinear propagation of ion-acoustic (IA) solitary waves (SWs) in a four-component non-extensive multi-ion plasma system containing inertial positively charged light ions, negatively charged heavy ions, as well as noninertial nonextensive electrons and positrons has been theoretically investigated. The reductive perturbation method has been employed to derive the nonlinear equations, namely, Korteweg−deVries (KdV), modified KdV (mKdV), and Gardner equations. The basic features (viz. polarity, amplitude, width, etc.) of Gardner solitons are found to exist beyond the KdV limit and these IA Gardner solitons are qualitatively different from the KdV and mKdV solitons. It is observed that the basic features of IA SWs are modified by various plasma parameters (viz. electron and positron nonextensivity, electron number density to ion number density, and electron temperature to positron temperature, etc.) of the considered plasma system. The results obtained from this theoretical investigation may be useful in understanding the basic features of IA SWs propagating in both space and laboratory plasmas.

Generalized Lenard-Balescu calculations of electron-ion temperature relaxation in beryllium plasma.

Science.gov (United States)

Fu, Zhen-Guo; Wang, Zhigang; Li, Da-Fang; Kang, Wei; Zhang, Ping

2015-09-01

The problem of electron-ion temperature relaxation in beryllium plasma at various densities (0.185-18.5g/cm^{3}) and temperatures [(1.0-8)×10^{3} eV] is investigated by using the generalized Lenard-Balescu theory. We consider the correlation effects between electrons and ions via classical and quantum static local field corrections. The numerical results show that the electron-ion pair distribution function at the origin approaches the maximum when the electron-electron coupling parameter equals unity. The classical result of the Coulomb logarithm is in agreement with the quantum result in both the weak (Γ_{ee}1) electron-electron coupling ranges, whereas it deviates from the quantum result at intermediate values of the coupling parameter (10^{-2}Coulomb logarithm will decrease and the corresponding relaxation rate ν_{ie} will increase. In addition, a simple fitting law ν_{ie}/ν_{ie}^{(0)}=a(ρ_{Be}/ρ_{0})^{b} is determined, where ν_{ie}^{(0)} is the relaxation rate corresponding to the normal metal density of Be and ρ_{0}, a, and b are the fitting parameters related to the temperature and the degree of ionization 〈Z〉 of the system. Our results are expected to be useful for future inertial confinement fusion experiments involving Be plasma.

Solar cycle variation of interstellar neutral He, Ne, O density and pick-up ions along the Earth's orbit

OpenAIRE

Sokół, Justyna M.; Bzowski, Maciej; Kubiak, Marzena A.; Möbius, Eberhard

2016-01-01

We simulated the modulation of the interstellar neutral (ISN) He, Ne, and O density and pick-up ion (PUI) production rate and count rate along the Earth's orbit over the solar cycle from 2002 to 2013 to verify if solar cycle-related effects may modify the inferred ecliptic longitude of the ISN inflow direction. We adopted the classical PUI model with isotropic distribution function and adiabatic cooling, modified by time- and heliolatitude-dependent ionization rates and non-zero injection spe...

Resolving key heavy-ion fusion target issues with relativistic heavy-ion research accelerators

International Nuclear Information System (INIS)

Arnold, R.C.

1988-01-01

Heavy-ion accelerators designed for relativistic nuclear research experiments can also be adapted for target research in heavy-ion driver inertial fusion. Needle-shaped plasmas can be created that are adequate for studying basic properties of matter at high energy density. Although the ion range is very long, the specific deposited power nevertheless increases with kinetic energy, as the focus spot can be made smaller and more ions can be accumulated in larger rings

Improved GAMMA 10 tandem mirror confinement in high density plasma

International Nuclear Information System (INIS)

Yatsu, K.; Cho, T.; Higaki, H.; Hirata, M.; Hojo, H.; Ichimura, M.; Ishii, K.; Ishimoto, Y.; Itakura, A.; Katanuma, I.; Kohagura, J.; Minami, R.; Nakashima, Y.; Numakura, T.; Saito, T.; Saosaki, S.; Takemura, Y.; Tatematsu, Y.; Yoshida, M.; Yoshikawa, M.

2003-01-01

GAMMA 10 experiments have advanced in high density experiments after the last IAEA fusion energy conference in 2000 where we reported the production of the high density plasma through use of ion cyclotron range of frequency heating at a high harmonic frequency and neutral beam injection in the anchor cells. However, the diamagnetic signal of the plasma decreased when electron cyclotron resonance heating was applied for the potential formation. Recently a high density plasma has been obtained without degradation of the diamagnetic signal and with much improved reproducibility than before. The high density plasma was attained through adjustment of the spacing of the conducting plates installed in the anchor transition regions. The potential confinement of the plasma has been extensively studied. Dependences of the ion confinement time, ion-energy confinement time and plasma confining potential on plasma density were obtained for the first time in the high density region up to a density of 4x10 18 m -3 . (author)

Ion extraction in the cyclotron geometry

International Nuclear Information System (INIS)

Rodenburg, R.E.

1985-01-01

The detailed physics of ion beam extraction from a plasma column by intense sinusoidal radio frequency (rf) electric fields at the ion cyclotron frequency omega/sub ci/ and its harmonics is experimentally studied. Results describe the instantaneous relationship - within one rf period of approx. = 3009 nsec - between applied rf, the plasma response and the ions expelled by rf and plasma fields. Reflex discharges in H 2 , D 2 , and He with ion and electron densities greater than or equal to10 11 cm -3 are subjected to 0-5 kV zero-to-peak rf electric fields E vector and 0.65-9.00 kG background magnetic fields B 0 vector with E vector perpendicular to B 0 vector. Ion currents up to 200 μA are extracted. Nonperturbing optical diagnostics measure the relative amplitude and phase of instantaneous ion and electron density fluctuations induced by the rf during each rf cycle and the time variation of extracted ion bursts, the latter made possible by the use of a phosphor beam-stop. Detailed dependences on external electric and magnetic fields are reported. The plasma density fluctuations are in good agreement with the dispersion relation for electrostatic ion cyclotron waves (EICW), and the beam data show current enhancement at the second harmonic over that at the fundamental and evidence for a radically different mechanism for the rf-driven ion extraction process than conventional wisdom assumes. This work represents the first detailed, systematic study of the ac ion extraction process

Proposal for the Study of Thermophysical Properties of High-Energy-Density Matter Using Current and Future Heavy-Ion Accelerator Facilities at GSI Darmstadt

International Nuclear Information System (INIS)

Tahir, N.A.; Spiller, P.; Deutsch, C.; Fortov, V.E.; Gryaznov, V.; Kulish, M.; Lomonosov, I.V.; Mintsev, V.; Nikolaev, D.; Shilkin, N.; Shutov, A.; Ternovoi, V.; Hoffmann, D.H.H.; Ni, P.; Udrea, S.; Varentsov, D.; Piriz, A.R.; Temporal, M.

2005-01-01

The subject of high-energy-density (HED) states in matter is of considerable importance to numerous branches of basic as well as applied physics. Intense heavy-ion beams are an excellent tool to create large samples of HED matter in the laboratory with fairly uniform physical conditions. Gesellschaft fuer Schwerionenforschung, Darmstadt, is a unique worldwide laboratory that has a heavy-ion synchrotron, SIS18, that delivers intense beams of energetic heavy ions. Construction of a much more powerful synchrotron, SIS100, at the future international facility for antiprotons and ion research (FAIR) at Darmstadt will lead to an increase in beam intensity by 3 orders of magnitude compared to what is currently available. The purpose of this Letter is to investigate with the help of two-dimensional numerical simulations, the potential of the FAIR to carry out research in the field of HED states in matter

Ion Bernstein wave experiments on the Alcator C tokamak

International Nuclear Information System (INIS)

Moody, J.D.

1988-09-01

Ion Bernstein wave experiments are carried out on the Alcator C tokamak to study wave excitation, propagation, absorption, and plasma heating due to wave power absorption. It is shown that ion Bernstein wave power is coupled into the plasma and follows the expected dispersion relation. The antenna loading is maximized when the hydrogen second harmonic layer is positioned just behind the antenna. Plasma heating results at three values of the toroidal magnetic field are presented. Central ion temperature increases of ΔT/sub i//Ti /approx lt/ 0.1 and density increases Δn/n 6 s/sup /minus/1/ for plasmas within the density range 0.6 /times/ 10 20 m/sup /minus/3/ ≤ /bar n//sub e/ ≤ 4 /times/ 10 20 m/sup /minus/3/ and magnetic fields 2.4 ≥ ω/Ω/sub H/ ≥ 1.1. The density increases is usually accompanied by an improvement in the global particle confinement time relative to the Ohmic value. The ion heating rate is measured to be ΔT/sub i//P/sub rf/ ≅ 2-4.5 eV/kW at low densities. At higher densities /bar n//sub e/ ≤ 1.5 /times/ 10 20 m/sup /minus/3/ the ion heating rate dramatically decreases. It is shown that the decrease in the ion heating rate can be explained by the combined effects of wave scattering through the edge turbulence and the decreasing on energy confinement of these discharges with density. The effect of observed edge turbulence is shown to cause a broadening of the rf power deposition profile with increasing density. It is shown that the inferred value of the Ohmic ion thermal conduction, when compared to the Chang-Hinton neoclassical prediction, exhibits an increasing anomaly with increasing plasma density

Shot-to-shot reproducibility of a self-magnetically insulated ion diode

International Nuclear Information System (INIS)

Pushkarev, A. I.; Isakova, Yu. I.; Khailov, I. P.

2012-01-01

In this paper we present the analysis of shot to shot reproducibility of the ion beam which is formed by a self-magnetically insulated ion diode with an explosive emission graphite cathode. The experiments were carried out with the TEMP-4M accelerator operating in double-pulse mode: the first pulse is of negative polarity (300–500 ns, 100–150 kV), and this is followed by a second pulse of positive polarity (150 ns, 250–300 kV). The ion current density was 10–70 A/cm 2 depending on the diode geometry. The beam was composed from carbon ions (80%–85%) and protons. It was found that shot to shot variation in the ion current density was about 35%–40%, whilst the diode voltage and current were comparatively stable with the variation limited to no more than 10%. It was shown that focusing of the ion beam can improve the stability of the ion current generation and reduces the variation to 18%–20%. In order to find out the reason for the shot-to-shot variation in ion current density we examined the statistical correlation between the current density of the accelerated beam and other measured characteristics of the diode, such as the accelerating voltage, total current, and first pulse duration. The correlation between the ion current density measured simultaneously at different positions within the cross-section of the beam was also investigated. It was shown that the shot-to-shot variation in ion current density is mainly attributed to the variation in the density of electrons diffusing from the drift region into the A-K gap.

Effect of negative ions on the formation of weak ion acoustic double layers

International Nuclear Information System (INIS)

Kalita, M.K.; Bujarbarua, S.

1985-01-01

Using kinetic theory, small amplitude double layers associated with ion acoustic waves in a plasma containing negative species of ions were investigated. Analytic solution for the double layer potential was carried out. The limiting values of the negative ion density for the existence of this type of DL were calculated and the application of this result to space plasmas is discussed. (author)

Temperature, pressure, and density of electron, atom and ion, in the breaking arc of silver-cadmium contacts used in medium current region

International Nuclear Information System (INIS)

Aida, Teizo

1979-01-01

Wear of silver-cadmium contacts at the time of breaking was studied. The materials of the contacts were silver-cadmium alloy and silver-cadmium oxide sinter. The spectra of arc discharge generated at the time of breaking contact were analyzed with a monochromator photo multiplier. The ratio of the densities of cadmium and silver atoms in the arc can be estimated from the observed intensities of spectrum lines. The electron density is obtained from the arc current density. The proportion of the cadmium atoms in the arc was about 30 percent. The densities of silver atoms and cadmium atoms can be estimated by the principle of thermal ionization equilibrium. The ion densities were also estimated. The partial pressures of silver and cadmium atoms in the arc can be obtained from the Boyle-Charles' law. A formula which gives the number of atoms liberated from the surfaces of contacts at the time of breaking was given by Boddy et al. (Kato, T.)

The dawn–dusk asymmetry of ion density in the dayside magnetosheath and its annual variability measured by THEMIS

Directory of Open Access Journals (Sweden)

A. P. Dimmock

2016-05-01

Full Text Available The local and global plasma properties in the magnetosheath play a fundamental role in regulating solar wind–magnetosphere coupling processes. However, the magnetosheath is a complex region to characterise as it has been shown theoretically, observationally and through simulations that plasma properties are inhomogeneous, non-isotropic and asymmetric about the Sun-Earth line. To complicate matters, dawn–dusk asymmetries are sensitive to various changes in the upstream conditions on an array of timescales. The present paper focuses exclusively on dawn–dusk asymmetries, in particularly that of ion density. We present a statistical study using THEMIS data of the dawn–dusk asymmetry of ion density in the dayside magnetosheath and its long-term variations between 2009 and 2015. Our data suggest that, in general, the dawn-side densities are higher, and the asymmetry grows from noon towards the terminator. This trend was only observed close to the magnetopause and not in the central magnetosheath. In addition, between 2009 and 2015, the largest asymmetry occurred around 2009 decreasing thereafter. We also concluded that no single parameter such as the Alfvén Mach number, plasma velocity, or the interplanetary magnetic field strength could exclusively account for the observed asymmetry. Interestingly, the dependence on Alfvén Mach number differed between data sets from different time periods. The asymmetry obtained in the THEMIS data set is consistent with previous studies, but the solar cycle dependence was opposite to an analysis based on IMP-8 data. We discuss the physical mechanisms for this asymmetry and its temporal variation. We also put the current results into context with the existing literature in order to relate THEMIS era measurements to those made during earlier solar cycles.

Space-charge compensation of highly charged ion beam from laser ion source

International Nuclear Information System (INIS)

Kondrashev, S.A.; Collier, J.; Sherwood, T.R.

1996-01-01

The problem of matching an ion beam delivered by a high-intensity ion source with an accelerator is considered. The experimental results of highly charged ion beam transport with space-charge compensation by electrons are presented. A tungsten thermionic cathode is used as a source of electrons for beam compensation. An increase of ion beam current density by a factor of 25 is obtained as a result of space-charge compensation at a distance of 3 m from the extraction system. The process of ion beam space-charge compensation, requirements for a source of electrons, and the influence of recombination losses in a space-charge-compensated ion beam are discussed. (author)

A double-layer based model of ion confinement in electron cyclotron resonance ion source

Energy Technology Data Exchange (ETDEWEB)

Mascali, D., E-mail: davidmascali@lns.infn.it; Neri, L.; Celona, L.; Castro, G.; Gammino, S.; Ciavola, G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Torrisi, G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Università Mediterranea di Reggio Calabria, Dipartimento di Ingegneria dell’Informazione, delle Infrastrutture e dell’Energia Sostenibile, Via Graziella, I-89100 Reggio Calabria (Italy); Sorbello, G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Ingegneria Elettrica Elettronica ed Informatica, Viale Andrea Doria 6, 95125 Catania (Italy)

2014-02-15

The paper proposes a new model of ion confinement in ECRIS, which can be easily generalized to any magnetic configuration characterized by closed magnetic surfaces. Traditionally, ion confinement in B-min configurations is ascribed to a negative potential dip due to superhot electrons, adiabatically confined by the magneto-static field. However, kinetic simulations including RF heating affected by cavity modes structures indicate that high energy electrons populate just a thin slab overlapping the ECR layer, while their density drops down of more than one order of magnitude outside. Ions, instead, diffuse across the electron layer due to their high collisionality. This is the proper physical condition to establish a double-layer (DL) configuration which self-consistently originates a potential barrier; this “barrier” confines the ions inside the plasma core surrounded by the ECR surface. The paper will describe a simplified ion confinement model based on plasma density non-homogeneity and DL formation.

Ion acoustic solitons in a plasma with two-temperature kappa-distributed electrons

International Nuclear Information System (INIS)

Baluku, T. K.; Hellberg, M. A.

2012-01-01

Existence domains and characteristics of ion acoustic solitons are studied in a two-temperature electron plasma with both electron components being kappa-distributed, as found in Saturn's magnetosphere. As is the case for double-Boltzmann electrons, solitons of both polarities can exist over restricted ranges of fractional hot electron density ratio for this plasma model. Low κ values, which indicate increased suprathermal particles in the tail of the distribution, yield a smaller domain in the parameter space of hot density fraction and normalized soliton velocity (f, M), over which both soliton polarities are supported for a given plasma composition (the coexistence region). For some density ratios that support coexistence, solitons occur even at the lowest (critical) Mach number (i.e., at the acoustic speed), as found recently for a number of other plasma models. Like Maxwellians, low-κ distributions also support positive potential double layers over a narrow range of low fractional cool electron density (<10%).

Ion acoustic solitons in a plasma with two-temperature kappa-distributed electrons

Energy Technology Data Exchange (ETDEWEB)

Baluku, T. K.; Hellberg, M. A. [School of Physics, University of KwaZulu-Natal, Private Bag X54001, Durban 4000 (South Africa)

2012-01-15

Existence domains and characteristics of ion acoustic solitons are studied in a two-temperature electron plasma with both electron components being kappa-distributed, as found in Saturn's magnetosphere. As is the case for double-Boltzmann electrons, solitons of both polarities can exist over restricted ranges of fractional hot electron density ratio for this plasma model. Low {kappa} values, which indicate increased suprathermal particles in the tail of the distribution, yield a smaller domain in the parameter space of hot density fraction and normalized soliton velocity (f, M), over which both soliton polarities are supported for a given plasma composition (the coexistence region). For some density ratios that support coexistence, solitons occur even at the lowest (critical) Mach number (i.e., at the acoustic speed), as found recently for a number of other plasma models. Like Maxwellians, low-{kappa} distributions also support positive potential double layers over a narrow range of low fractional cool electron density (<10%).

Effect of electronic spatial extents (ESE) of ions on overpotential of lithium ion capacitors

International Nuclear Information System (INIS)

Xu, Fan; Lee, Chung ho; Koo, Chong Min; Jung, Cheolsoo

2014-01-01

Highlights: •Electronic spatial extent (ESE) of ion characterizes its electron density volume. •The ESE of ion proposes to assess overpotential of nanoporous capacitor. •Anion with low ESE shows low overpotential of the capacitor. •The ESE is more realistic to assess overpotential than conductivity or ion size. -- Abstract: The electronic spatial extent (ESE) of ions was defined as a major concept for assessing the cause of overpotential in the charging and discharging processes of a nanoporous activated carbon (AC) electrode. The performance degradation of AC/Li half-cells was caused by the overpotential, which was in discord with the electrolyte conductivity and ion size. Compared to the overpotential with the salt concentration, the AC/Li half-cell with a high concentration had a smaller overpotential, and its discharge patterns were similar to the curves obtained from the half-cells with a smaller ESE of BF 4 − ion. The ESE is a more realistic solution for determining the overpotential of the nanoporous capacitor, such as supercapacitor and Li ion capacitor, because its capacity is dependent on the electron density at the electric double layer of the capacitor electrode

Equatorial density depletions observed at 840 km during the great magnetic storm of March 1989

International Nuclear Information System (INIS)

Greenspan, M.E.; Rasmussen, C.E.; Burke, W.J.; Abdu, M.A.

1991-01-01

Early on March 14, 1989, a thermal plasma probe on the Defense Meteorological Satellite Program (DMSP) F9 spacecraft detected extensive and dramatic decreases in the ion density at 840 km, near 2130 LT, during two consecutive transequatorial passes over South America. The order of magnitude decreases in the ion density extended more than 4,000 km along the satellite track. The depletions were accompanied by upward and westward plasma drifts, both in excess of 100 m/s. Their onsets and terminations were marked by extremely sharp density gradients. A partial depletion was detected over the eastern Pacific during the following orbit. The DMSP F9 ground track passed slightly west of a Brazilian total electron content (TEC) station and two Brazilian ionosondes during the first depletion encounter. The TEC fell far below normal during the night of March 13-14. The ionosonde measurements indicate that, in the hour after sunset, before DMSP passed through the depletions, the F 2 layer rose rapidly and disappeared, but at the time of the first depletion encounter, h m F 2 was decreasing over one of the stations. The authors develop a phenomenological model reconciling DMSP F8, F9 and ground-based measurements. The calculations show that rapid upward drifts sustained for several hours can produce depletions in the equatorial ion density with sharp gradients at their high-latitude boundaries, consistent with the data. They discuss possible contributing mechanisms for generating these upward drifts. These include direct penetration of the magnetospheric electric field to low latitudes, the electric fields generated by the disturbance dynamo, and the effects of conductivity gradients near the dusk terminator and the South Atlantic anomaly

A statistical study of coronal densities from X-ray line ratios of helium-like ions - Ne IX and Mg XI

Science.gov (United States)

Linford, G. A.; Lemen, J. R.; Strong, K. T.

1988-01-01

Since the repair of the Solar Maximum Mission (SMM) spacecraft, the Flat Crystal Spectrometer (FCS) has recorded many high temperature spectra of helium-like ions under a wide variety of coronal conditions including active regions, long duration events, compact events, and double flares. The plasma density and temperature are derived from the ratios R and G, where R = f/i, G = (f + i)/r, and r, f, and i denote the resonance, forbidden, and intercombination line fluxes. A new method for obtaining the density and temperature for events observed with the FCS aboard SMM is presented. The results for these events are presented and compared to earlier results, and the method is evaluated based on these comparisons.

Helicon normal modes in Proto-MPEX

Science.gov (United States)

Piotrowicz, P. A.; Caneses, J. F.; Green, D. L.; Goulding, R. H.; Lau, C.; Caughman, J. B. O.; Rapp, J.; Ruzic, D. N.

2018-05-01

The Proto-MPEX helicon source has been operating in a high electron density ‘helicon-mode’. Establishing plasma densities and magnetic field strengths under the antenna that allow for the formation of normal modes of the fast-wave are believed to be responsible for the ‘helicon-mode’. A 2D finite-element full-wave model of the helicon antenna on Proto-MPEX is used to identify the fast-wave normal modes responsible for the steady-state electron density profile produced by the source. We also show through the simulation that in the regions of operation in which core power deposition is maximum the slow-wave does not deposit significant power besides directly under the antenna. In the case of a simulation where a normal mode is not excited significant edge power is deposited in the mirror region. ).

Specific ion effects on membrane potential and the permselectivity of ion exchange membranes.

Science.gov (United States)

Geise, Geoffrey M; Cassady, Harrison J; Paul, Donald R; Logan, Bruce E; Hickner, Michael A

2014-10-21

Membrane potential and permselectivity are critical parameters for a variety of electrochemically-driven separation and energy technologies. An electric potential is developed when a membrane separates electrolyte solutions of different concentrations, and a permselective membrane allows specific species to be transported while restricting the passage of other species. Ion exchange membranes are commonly used in applications that require advanced ionic electrolytes and span technologies such as alkaline batteries to ammonium bicarbonate reverse electrodialysis, but membranes are often only characterized in sodium chloride solutions. Our goal in this work was to better understand membrane behaviour in aqueous ammonium bicarbonate, which is of interest for closed-loop energy generation processes. Here we characterized the permselectivity of four commercial ion exchange membranes in aqueous solutions of sodium chloride, ammonium chloride, sodium bicarbonate, and ammonium bicarbonate. This stepwise approach, using four different ions in aqueous solution, was used to better understand how these specific ions affect ion transport in ion exchange membranes. Characterization of cation and anion exchange membrane permselectivity, using these ions, is discussed from the perspective of the difference in the physical chemistry of the hydrated ions, along with an accompanying re-derivation and examination of the basic equations that describe membrane potential. In general, permselectivity was highest in sodium chloride and lowest in ammonium bicarbonate solutions, and the nature of both the counter- and co-ions appeared to influence measured permselectivity. The counter-ion type influences the binding affinity between counter-ions and polymer fixed charge groups, and higher binding affinity between fixed charge sites and counter-ions within the membrane decreases the effective membrane charge density. As a result permselectivity decreases. The charge density and polarizability

Cometary pick-up ions observed near Giacobini-Zinner

Science.gov (United States)

Gloeckler, G.; Hovestadt, D.; Ipavich, F. M.; Scholer, M.; Klecker, B.

1986-01-01

The number and energy density of cometary water-group ions observed near Comet Giacobini-Zinner are derived using the rest-frame distribution functions. The data reveal that density profiles of inbound and outbound passes and their shape correlate with pick-up ion production model predictions. The lose rate and production rate of water-group cometary molecules calculated from predicted and measured density profiles are 2 x 10 to the -6th/sec and 2.6 x 10 to the 28th/sec respectively. The shapes of the distribution functions are examined to study the solar wind/cometary ions interaction process.

Effect of finite ion-temperature on ion-acoustic solitary waves in an inhomogeneous plasma

International Nuclear Information System (INIS)

Shivamoggi, B.K.

1981-01-01

The propagation of weakly nonlinear ion-acoustic waves in an inhomogeneous plasma is studied taking into account the effect of finite ion temperature. It is found that, whereas both the amplitude and the velocity of propagation decrease as the ion-acoustic solitary wave propagates into regions of higher density, the effect of a finite ion temperature is to reduce the amplitude but enhance the velocity of propagation of the solitary wave. (author)

The evolution of ring current ion energy density and energy content during geomagnetic storms based on Van Allen Probes measurements

International Nuclear Information System (INIS)

Zhao, H.; University of Colorado, Boulder, CO; Li, X.; University of Colorado, Boulder, CO; Baker, D. N.

2015-01-01

Enabled by the comprehensive measurements from the Magnetic Electron Ion Spectrometer (MagEIS), Helium Oxygen Proton Electron mass spectrometer (HOPE), and Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of ions with different energies and species to the ring current energy density and their dependence on the phases of geomagnetic storms are quantified. The results show that lower energy (<50 keV) protons enhance much more often and also decay much faster than higher-energy protons. During the storm main phase, ions with energies <50 keV contribute more significantly to the ring current than those with higher energies; while the higher-energy protons dominate during the recovery phase and quiet times. The enhancements of higher-energy proton fluxes as well as energy content generally occur later than those of lower energy protons, which could be due to the inward radial diffusion. For the 29 March 2013 storm we investigated in detail that the contribution from O + is ~25% of the ring current energy content during the main phase and the majority of that comes from <50 keV O + . This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions. Using the Dessler-Parker-Sckopke relation, the contributions of ring current particles to the magnetic field depression during this geomagnetic storm are also calculated. In conclusion, the results show that the measured ring current ions contribute about half of the Dst depression.

Multiphoton ionization of many-electron atoms and highly-charged ions in intense laser fields: a relativistic time-dependent density functional theory approach

Science.gov (United States)

Tumakov, Dmitry A.; Telnov, Dmitry A.; Maltsev, Ilia A.; Plunien, Günter; Shabaev, Vladimir M.

2017-10-01

We develop an efficient numerical implementation of the relativistic time-dependent density functional theory (RTDDFT) to study multielectron highly-charged ions subject to intense linearly-polarized laser fields. The interaction with the electromagnetic field is described within the electric dipole approximation. The resulting time-dependent relativistic Kohn-Sham (RKS) equations possess an axial symmetry and are solved accurately and efficiently with the help of the time-dependent generalized pseudospectral method. As a case study, we calculate multiphoton ionization probabilities of the neutral argon atom and argon-like xenon ion. Relativistic effects are assessed by comparison of our present results with existing non-relativistic data.

Formation of tripolar vortices in toroidal ion-temperature-gradient driven modes in the presence of dust contamination

International Nuclear Information System (INIS)

Mirza, Arshad M.; Qamar, Anisa; Khan, M. Yaqub; Ayub, M.

2007-01-01

A system of nonlinear equations that governs the dynamics of toroidal-ion-temperature-gradient (TITG) driven modes in the presence of dust contamination is presented. In the linear limit, a local dispersion relation is derived and analyzed for a flat density profile case. In the nonlinear case, and by taking some specific profiles of equilibrium density, ion temperature, magnetic field, and sheared plasma flows, the stationary solutions of the nonlinear system can be represented in the form of a tripolar vortex solution. Numerical results obtained in the present study show that the inclusion of dust modifies the nonlinear vortical structures, and the amplitude of the normalized potential is found to be increased in the presence of negatively charged dust grains. The results of our present investigation would be useful to understand some linear as well as nonlinear properties of TITG modes in a dust-contaminated tokamak plasma

What Are Normal Metal Ion Levels After Total Hip Arthroplasty? A Serologic Analysis of Four Bearing Surfaces.

Science.gov (United States)

Barlow, Brian T; Ortiz, Philippe A; Boles, John W; Lee, Yuo-Yu; Padgett, Douglas E; Westrich, Geoffrey H

2017-05-01

The recent experiences with adverse local tissue reactions have highlighted the need to establish what are normal serum levels of cobalt (Co), chromium (Cr), and titanium (Ti) after hip arthroplasty. Serum Co, Cr, and Ti levels were measured in 80 nonconsecutive patients with well-functioning unilateral total hip arthroplasty and compared among 4 bearing surfaces: ceramic-on-ceramic (CoC); ceramic-on-polyethylene (CoP); metal-on-polyethylene (MoP), and dual mobility (DM). The preoperative and most recent University of California, Los Angeles (UCLA) and Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores were compared among the different bearing surfaces. No significant difference was found among serum Co and Cr levels between the 4 bearing surface groups (P = .0609 and P = .1577). Secondary analysis comparing metal and ceramic femoral heads demonstrated that the metal group (MoP, modular dual mobility (Stryker Orthopedics, Mahwah, NJ) [metal]) had significant higher serum Co levels compared with the ceramic group (CoC, CoP, MDM [ceramic]) (1.05 mg/L ± 1.25 vs 0.59 mg/L ± 0.24; P = .0411). Spearman coefficient identified no correlation between metal ion levels and patient-reported outcome scores. No serum metal ion level differences were found among well-functioning total hip arthroplasty with modern bearing couples. Significantly higher serum Co levels were seen when comparing metal vs ceramic femoral heads in this study and warrants further investigation. Metal ion levels did not correlate with patient-reported outcome measures. Copyright © 2016 Elsevier Inc. All rights reserved.

Quantiles for Finite Mixtures of Normal Distributions

Science.gov (United States)

Rahman, Mezbahur; Rahman, Rumanur; Pearson, Larry M.

2006-01-01

Quantiles for finite mixtures of normal distributions are computed. The difference between a linear combination of independent normal random variables and a linear combination of independent normal densities is emphasized. (Contains 3 tables and 1 figure.)

Ion colliders

Energy Technology Data Exchange (ETDEWEB)

Fischer, W.

2011-12-01

Ion colliders are research tools for high-energy nuclear physics, and are used to test the theory of Quantum Chromo Dynamics (QCD). The collisions of fully stripped high-energy ions create matter of a temperature and density that existed only microseconds after the Big Bang. Ion colliders can reach higher densities and temperatures than fixed target experiments although at a much lower luminosity. The first ion collider was the CERN Intersecting Storage Ring (ISR), which collided light ions [77Asb1, 81Bou1]. The BNL Relativistic Heavy Ion Collider (RHIC) is in operation since 2000 and has collided a number of species at numerous energies. The CERN Large Hadron Collider (LHC) started the heavy ion program in 2010. Table 1 shows all previous and the currently planned running modes for ISR, RHIC, and LHC. All three machines also collide protons, which are spin-polarized in RHIC. Ion colliders differ from proton or antiproton colliders in a number of ways: the preparation of the ions in the source and the pre-injector chain is limited by other effects than for protons; frequent changes in the collision energy and particle species, including asymmetric species, are typical; and the interaction of ions with each other and accelerator components is different from protons, which has implications for collision products, collimation, the beam dump, and intercepting instrumentation devices such a profile monitors. In the preparation for the collider use the charge state Z of the ions is successively increased to minimize the effects of space charge, intrabeam scattering (IBS), charge change effects (electron capture and stripping), and ion-impact desorption after beam loss. Low charge states reduce space charge, intrabeam scattering, and electron capture effects. High charge states reduce electron stripping, and make bending and acceleration more effective. Electron stripping at higher energies is generally more efficient. Table 2 shows the charge states and energies in the

Ion colliders

International Nuclear Information System (INIS)

Fischer, W.

2010-01-01

Ion colliders are research tools for high-energy nuclear physics, and are used to test the theory of Quantum Chromo Dynamics (QCD). The collisions of fully stripped high-energy ions create matter of a temperature and density that existed only microseconds after the Big Bang. Ion colliders can reach higher densities and temperatures than fixed target experiments although at a much lower luminosity. The first ion collider was the CERN Intersecting Storage Ring (ISR), which collided light ions (77Asb1, 81Bou1). The BNL Relativistic Heavy Ion Collider (RHIC) is in operation since 2000 and has collided a number of species at numerous energies. The CERN Large Hadron Collider (LHC) started the heavy ion program in 2010. Table 1 shows all previous and the currently planned running modes for ISR, RHIC, and LHC. All three machines also collide protons, which are spin-polarized in RHIC. Ion colliders differ from proton or antiproton colliders in a number of ways: the preparation of the ions in the source and the pre-injector chain is limited by other effects than for protons; frequent changes in the collision energy and particle species, including asymmetric species, are typical; and the interaction of ions with each other and accelerator components is different from protons, which has implications for collision products, collimation, the beam dump, and intercepting instrumentation devices such a profile monitors. In the preparation for the collider use the charge state Z of the ions is successively increased to minimize the effects of space charge, intrabeam scattering (IBS), charge change effects (electron capture and stripping), and ion-impact desorption after beam loss. Low charge states reduce space charge, intrabeam scattering, and electron capture effects. High charge states reduce electron stripping, and make bending and acceleration more effective. Electron stripping at higher energies is generally more efficient. Table 2 shows the charge states and energies in the

Si clusters/defective graphene composites as Li-ion batteries anode materials: A density functional study

International Nuclear Information System (INIS)

Li, Meng; Liu, Yue-Jie; Zhao, Jing-xiang; Wang, Xiao-guang

2015-01-01

Highlights: • We study the interaction between Si clusters with pristine and defective graphene. • We find that the binding strength of Si clusters on graphene can be enhanced to different degrees after introducing various defects. • It is found that both graphene and Si cluster in the Si/graphene composites can preserve their Li uptake ability. - Abstract: Recently, the Si/graphene hybrid composites have attracted considerable attention due to their potential application for Li-ion batteries. How to effectively anchor Si clusters to graphene substrates to ensure their stability is an important factor to determine their performance for Li-ion batteries. In the present work, we have performed comprehensive density functional theory (DFT) calculations to investigate the geometric structures, stability, and electronic properties of the deposited Si clusters on defective graphenes as well as their potential applications for Li-ion batteries. The results indicate that the interfacial bonding between these Si clusters with the pristine graphene is quietly weak with a small adsorption energy (<−0.21 eV). Due to the presence of vacancy site, the binding strength of Si clusters on defective graphene is much stronger than that of pristine one, accompanying with a certain amount of charge transfer from Si clusters to graphene substrates. Moreover, the ability of Si/graphene hybrids for Li uptake is studied by calculating the adsorption of Li atoms. We find that both graphenes and Si clusters in the Si/graphene composites preserve their Li uptake ability, indicating that graphenes not only server as buffer materials for accommodating the expansion of Si cluster, but also provide additional intercalation sites for Li

The Properties of the Space-Charge and Net Current Density in Magnetized Plasmas

International Nuclear Information System (INIS)

Hatami, M. M.

2013-01-01

A hydrodynamic model is used to investigate the properties of positive space-charge and net current density in the sheath region of magnetized, collisional plasmas with warm positive ions. It is shown that an increase in the ion-neutral collision frequency, as well as the magnitude of the external magnetic field, leads to an increase in the net current density across the sheath region. The results also show that the accumulation of positive ions in the sheath region increases by increasing the ion-neutral collision frequency and the magnitude of the magnetic field. In addition, it is seen that an increase in the positive ion temperatures causes a decrease in the accumulation of positive ions and the net current density in the sheath region. (basic plasma phenomena)

2D imaging of helium ion velocity in the DIII-D divertor

Science.gov (United States)

Samuell, C. M.; Porter, G. D.; Meyer, W. H.; Rognlien, T. D.; Allen, S. L.; Briesemeister, A.; Mclean, A. G.; Zeng, L.; Jaervinen, A. E.; Howard, J.

2018-05-01

Two-dimensional imaging of parallel ion velocities is compared to fluid modeling simulations to understand the role of ions in determining divertor conditions and benchmark the UEDGE fluid modeling code. Pure helium discharges are used so that spectroscopic He+ measurements represent the main-ion population at small electron temperatures. Electron temperatures and densities in the divertor match simulated values to within about 20%-30%, establishing the experiment/model match as being at least as good as those normally obtained in the more regularly simulated deuterium plasmas. He+ brightness (HeII) comparison indicates that the degree of detachment is captured well by UEDGE, principally due to the inclusion of E ×B drifts. Tomographically inverted Coherence Imaging Spectroscopy measurements are used to determine the He+ parallel velocities which display excellent agreement between the model and the experiment near the divertor target where He+ is predicted to be the main-ion species and where electron-dominated physics dictates the parallel momentum balance. Upstream near the X-point where He+ is a minority species and ion-dominated physics plays a more important role, there is an underestimation of the flow velocity magnitude by a factor of 2-3. These results indicate that more effort is required to be able to correctly predict ion momentum in these challenging regimes.

Chiral symmetry restoration versus deconfinement in heavy-ion collisions at high baryon density

Science.gov (United States)

Bratkovskaya, E. L.; Palmese, A.; Cassing, W.; Seifert, E.; Steinert, T.; Moreau, P.

2017-07-01

The effect of the chiral symmetry restoration (CSR) on observables from heavy-ion collisions is studied in the energy range \\sqrt{{s}NN}=3-20 {GeV} within the Parton-Hadron-String Dynamics (PHSD) transport approach. The PHSD includes the deconfinement phase transition as well as essential aspects of CSR in the dense and hot hadronic medium, which are incorporated in the Schwinger mechanism for the hadronic particle production. We adopt different parametrizations of the nuclear equation of state from the non-linear σ - ω model, which enter in the computation of the quark scalar density for the CSR mechanism, in order to estimate the uncertainty in our calculations. For the pion-nucleon Σ-term we adopt Σ π ≈ 45 MeV which corresponds to some ‘world average’. Our systematic studies show that chiral symmetry restoration plays a crucial role in the description of heavy-ion collisions at \\sqrt{{s}NN}=3-20 {GeV}, realizing an increase of the hadronic particle production in the strangeness sector with respect to the non-strange one. We identify particle abundances and rapidity spectra to be suitable probes in order to extract information about CSR, while transverse mass spectra are less sensitive. Our results provide a microscopic explanation for the “horn” structure in the excitation function of the K +/π + ratio: the CSR in the hadronic phase produces the steep increase of this particle ratio up to \\sqrt{{s}NN}≈ 7 {GeV}, while the drop at higher energies is associated to the appearance of a deconfined partonic medium.

Achieving maximum baryon densities

International Nuclear Information System (INIS)

Gyulassy, M.

1984-01-01

In continuing work on nuclear stopping power in the energy range E/sub lab/ approx. 10 GeV/nucleon, calculations were made of the energy and baryon densities that could be achieved in uranium-uranium collisions. Results are shown. The energy density reached could exceed 2 GeV/fm 3 and baryon densities could reach as high as ten times normal nuclear densities

Faraday cup for analyzing multi-ion plasma

International Nuclear Information System (INIS)

Fujita, Takao

1987-01-01

A compact and convenient ion analyzer (a kind of a Faraday cup) is developed in order to analyze weakly ionized multi-ion plasmas. This Faraday cup consists of three mesh electrodes and a movable ion collector. With a negative gate pulse superimposed on the ion retarding bias, ions are analyzed by means of time-of-flight. The identification of ion species and measurements of ion density and ion temperature are studied. (author)

Investigation on target normal sheath acceleration through measurements of ions energy distribution

Energy Technology Data Exchange (ETDEWEB)

Tudisco, S., E-mail: tudisco@lns.infn.it; Cirrone, G. A. P.; Mascali, D.; Schillaci, F. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Altana, C. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Via S. Sofia 64, 95123 Catania (Italy); Lanzalone, G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Università degli Studi di Enna “Kore,” Via delle Olimpiadi, 94100 Enna (Italy); Muoio, A. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Messina, Viale F.S. D’Alcontres 31, 98166 Messina (Italy); Brandi, F. [Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica, Intense Laser Irradiation Laboratory, Via G. Moruzzi 1, 56124 Pisa (Italy); Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Cristoforetti, G.; Ferrara, P.; Fulgentini, L.; Koester, P. [Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica, Intense Laser Irradiation Laboratory, Via G. Moruzzi 1, 56124 Pisa (Italy); Labate, L.; Gizzi, L. A. [Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica, Intense Laser Irradiation Laboratory, Via G. Moruzzi 1, 56124 Pisa (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); and others

2016-02-15

An experimental campaign aiming at investigating the ion acceleration mechanisms through laser-matter interaction in femtosecond domain has been carried out at the Intense Laser Irradiation Laboratory facility with a laser intensity of up to 2 × 10{sup 19} W/cm{sup 2}. A Thomson parabola spectrometer was used to obtain the spectra of the ions of the different species accelerated. Here, we show the energy spectra of light-ions and we discuss their dependence on structural characteristics of the target and the role of surface and target bulk in the acceleration process.

Investigation on target normal sheath acceleration through measurements of ions energy distribution

International Nuclear Information System (INIS)

Tudisco, S.; Cirrone, G. A. P.; Mascali, D.; Schillaci, F.; Altana, C.; Lanzalone, G.; Muoio, A.; Brandi, F.; Cristoforetti, G.; Ferrara, P.; Fulgentini, L.; Koester, P.; Labate, L.; Gizzi, L. A.

2016-01-01

An experimental campaign aiming at investigating the ion acceleration mechanisms through laser-matter interaction in femtosecond domain has been carried out at the Intense Laser Irradiation Laboratory facility with a laser intensity of up to 2 × 10 19 W/cm 2 . A Thomson parabola spectrometer was used to obtain the spectra of the ions of the different species accelerated. Here, we show the energy spectra of light-ions and we discuss their dependence on structural characteristics of the target and the role of surface and target bulk in the acceleration process

Planar-channeling spatial density under statistical equilibrium

International Nuclear Information System (INIS)

Ellison, J.A.; Picraux, S.T.

1978-01-01

The phase-space density for planar channeled particles has been derived for the continuum model under statistical equilibrium. This is used to obtain the particle spatial probability density as a function of incident angle. The spatial density is shown to depend on only two parameters, a normalized incident angle and a normalized planar spacing. This normalization is used to obtain, by numerical calculation, a set of universal curves for the spatial density and also for the channeled-particle wavelength as a function of amplitude. Using these universal curves, the statistical-equilibrium spatial density and the channeled-particle wavelength can be easily obtained for any case for which the continuum model can be applied. Also, a new one-parameter analytic approximation to the spatial density is developed. This parabolic approximation is shown to give excellent agreement with the exact calculations

Generation and focusing of intense ion beams with an inverse pinch ion diode

International Nuclear Information System (INIS)

Hashimoto, Yoshiyuki; Sato, Morihiko; Yatsuzuka, Mitsuyasu; Nobuhara, Sadao

1992-01-01

Generation and focusing of ion beams using an inverse pinch ion diode with a flat anode has been studied. The ion beams generated with the inverse pinch ion diode were found to be focused at 120 mm from the anode by the electrostatic field in the diode. The energy and maximum current density of the ion beams were 180 keV and 420 A/cm 2 , respectively. The focusing angle of the ion beams was 4.3deg. The beam brightness was estimated to be 1.3 GW/cm 2 ·rad 2 . The focusing distance of the ion beams was found to be controllable by changing the diameters of the anode and cathode. (author)

Optically pumped polarized H- ion source

International Nuclear Information System (INIS)

Anderson, L.W.

1986-01-01

The current status and future prospects for the optically pumped polarized H - ion source are discussed. At the present time H - ion currents of 60 μA and with a polarization of 65% have been produced. The ion current and polarization can be increased significantly if the optically pumped Na charge exchange target density and polarization can be increased. Studies of wall surfaces that permit many bounces before depolarizing the Na electron spin and studies of radiation trapping in optically pumped Na indicate that the Na target density and polarization can be increased substantially. 27 refs., 6 figs., 2 tabs

Ion Density Analysis of Single-Stranded DNA in Liquid Crystal

Science.gov (United States)

Iwabata, Kazuki; Seki, Yasutaka; Toizumi, Ryota; Shimada, Yuki; Furue, Hirokazu; Sakaguchi, Kengo

2013-09-01

With the widespread use of liquid crystals (LCs) in liquid crystal displays, we have looked into the application of liquid crystals in biotechnology. The purpose of the study described here is to investigate the physical properties of DNA using LCs. Synthetic oligonucleotide molecules were dispersed in MLC6884, the sample injected into antiparallel cells, and the amount of mobile ions was measured. The LC cell doped with oligonucleotide molecules showed a sequence-dependent, specific correlation between oligonucleotide concentration and the amount of mobile ions in the LC cells. In the framework of the Stokes model and polyacrylamide gel electrophoresis (PAGE) analysis, we speculate that this result arises from the difference in ion mobility, which is caused by the shape of the oligonucleotide molecule in the LC.

Mini biased collimated faraday cups for measurement of intense pulsed ion beams

International Nuclear Information System (INIS)

He Xiaoping; Shi Lei; Zhang Jiasheng; Qiu Aici

2000-01-01

An analysis of principle of a biased Faraday cup for measuring ion beams density and the main reasons related to the measuring accuracy were presented. An array of mini biased collimated Faraday cups was manufactured for the measurement of ion beam density of a compact 200 keV high power ion beam source. In the experiments the maximum density of ion beam was in the center of the beam, and it was about 170 A/cm 2

Ultra-relativistic heavy ions and cosmic rays

International Nuclear Information System (INIS)

McLerran, L.

1983-05-01

The collisions of ultra-relativistic heavy ions, E/sub /N/ greater than or equal to 1 TeV/nucleon are most interesting, since, at these energies, matter is produced at sufficiently high energy density that a quark-gluon plasma has a good chance to form. Very heavy ions are also most interesting since the matter forms in a larger volume than for light ions, and the matter is at a somewhat higher energy density. At very high energies with very heavy ions there is great flexibility in the experimental signals which might be studied, as well as the nature of the matter which is produced. The fragmentation region and central region provide different environments where a plasma might form. The former is baryon rich while the central region is high temperature with low baryon number density and is not accessible except at very high energies

Modification of solid surface by intense pulsed light-ion and metal-ion beams