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1

Structure of micro-instabilities in tokamak plasmas: Stiff transport or plasma eruptions?  

NASA Astrophysics Data System (ADS)

Solutions to a model 2D eigenmode equation describing micro-instabilities in tokamak plasmas are presented that demonstrate a sensitivity of the mode structure and stability to plasma profiles. In narrow regions of parameter space, with special plasma profiles, a maximally unstable mode is found that balloons on the outboard side of the tokamak. This corresponds to the conventional picture of a ballooning mode. However, for most profiles, this mode cannot exist, and instead, a more stable mode is found that balloons closer to the top or bottom of the plasma. Good quantitative agreement with a 1D ballooning analysis is found, provided the constraints associated with higher order profile effects, often neglected, are taken into account. A sudden transition from this general mode to the more unstable ballooning mode can occur for a critical flow shear, providing a candidate model for why some experiments observe small plasma eruptions (Edge Localised Modes, or ELMs) in place of large Type I ELMs.

Dickinson, D.; Roach, C. M.; Skipp, J. M.; Wilson, H. R.

2014-01-01

2

Kinetic Self-Organization of Microinstabilities in Astrophysical and in Laboratory Plasmas  

NASA Astrophysics Data System (ADS)

Microinstabilities can be considered as effective collisions. The small scale electromagnetic fluctuations due to microinstabilties can be considered as collisions on the particles, leading to a similar point-like and instantaneous-like change in the particle momentum. This paradigm, the anomalous transport paradigm, requires us to derive theories that can predict the correct transport parameters (particularly the anomalous viscosity and anomalous resistivity) from the properties of the microinstabilties. Our recent work [1-3] has shown that another possible effect of microinstabilties is to lead to a direct macroscopic change in the equilibrium by affecting the plasma flow, temperature anisotropy and current profile on a macroscopic level. Our previous work has focused on space and astrophysical systems. But similar effects can be considered for experimental plasmas. A particularly intriguing possible analogy is with zonal flows and ``angular momentum generation'' believed to be happening in accretion disks in astrophysical systems [4] and with the ``spontaneous toroidal rotation'' of axisymmetric plasmas in fusion devices such as Jet and Alcator C-Mod [5]. [1] G. Lapenta, J.U. Brackbill, W.S. Daughton, Phys. Plasmas, 10, 1577 (2003). [2] W. Daughton, G. Lapenta, P. Ricci, Phys. Rev. Lett., 93, 105004, 2004 [3] P. Ricci, J.U. Brackbill, W.S. Daughton, G. Lapenta, Phys. Plasmas, 11, 4102, 2004. [4] B. Coppi 2002 Nucl. Fusion 42 1-4 [5] E. S. Marmar, et al., Fusion Energy 2002 (IAEA, Vienna) Paper OV/4-1

Lapenta, Giovanni

2006-04-01

3

Microinstabilities in weak density gradient tokamak systems  

SciTech Connect

A prominent characteristic of auxiliary-heated tokamak discharges which exhibit improved (''H-mode type'') confinement properties is that their density profiles tend to be much flatter over most of the plasma radius. Depsite this favorable trend, it is emphasized here that, even in the limit of zero density gradient, low-frequency microinstabilities can persist due to the nonzero temperature gradient.

Tang, W.M.; Rewoldt, G.; Chen, L.

1986-04-01

4

Microinstabilities in the Gasdynamic Mirror Propulsion System  

NASA Technical Reports Server (NTRS)

The gasdynamic mirror has been proposed as a concept which could form the basis of a highly efficient fusion rocket engine. Gasdynamic mirrors differ from most other mirror type plasma confinement schemes in that they have much larger aspect ratios and operate at somewhat higher plasma densities. There are several types of instabilities which are known to plague mirror type confinement schemes. These instabilities fall into two general classes. One class of instability is the Magnetohdrodynamic or MHD instability which induces gross distortions in the plasma geometry. The other class of instability is the "loss cone" microinstability which leads to general plasma turbulence. The "loss cone" microinstability is caused by velocity space asymmetries resulting from the loss of plasma having constituent particle velocities within the angle of the magnetic mirror "loss cone." These instabilities generally manifest themselves in high temperature, moderately dense plasmas. The present study indicates that a GDM configured as a rocket engine might operate in a plasma regine where microinstabilities could potentially be significant.

Emrich, William

2005-01-01

5

Microinstabilities in the Gasdynamic Mirror Propulsion System  

NASA Technical Reports Server (NTRS)

The gasdynamic mirror has been proposed as a concept which could form the basis of a highly efficient fusion rocket engine. Gasdynamic mirrors differ from most other mirror type plasma confinement schemes in that they have much larger aspect ratios and operate at somewhat higher plasma densities. There are several types of instabilities which are known to plague mirror type confinement schemes. These instabilities fall into two general classes. One class of instability is the Magnetohydrodynamic or MHD instability which induces gross distortions in the plasma geometry. The other class of instability is the "loss cone" microinstability which leads to general plasma turbulence. The "loss cone" microinstability is caused by velocity space asymmetries resulting from the loss of plasma having constituent particle velocities within the angle of the magnetic mirror "loss cone." These instabilities generally manifest themselves in high temperature, moderately dense plasmas. The present study indicates that a GDM configured as a rocket engine might operate in a plasma regime where microinstabilities could potentially be significant.

Emrich, William

2005-01-01

6

Gyrokinetic Studies of Microinstabilities in the RFP  

E-print Network

An analytic equilibrium, the Toroidal Bessel Function Model, is used in conjunction with the gyrokinetic code GYRO to investigate the nature of microinstabilities in a reversed field pinch (RFP) plasma. The effect of the normalized electron plasma pressure ({\\beta}) on the characteristics of the microinstabilities is studied. A transition between an ion temperature gradient (ITG) driven mode and a microtearing mode as the dominant instability is found to occur at a {\\beta} value of approximately 4.5%. Suppression of the ITG mode occurs as in the tokamak, through coupling to shear Alfven waves, with a critical {\\beta} for stability higher than its tokamak equivalent due to a shorter parallel connection length. There is a steep dependence of the microtearing growth rate on temperature gradient suggesting high profile stiffness. There is evidence for a collisionless microtearing mode. The properties of this mode are investigated, and it is found that curvature drift plays an important role in the instability.

Carmody, Daniel; Terry, P W

2013-01-01

7

Review of electron beam microinstabilities and their relevance to EBIS devices  

SciTech Connect

Plasma kinetic theory and some examples of microinstabilities are briefly reviewed. Although the velocity space configuration of any EBIS is inherently susceptible to a number of classical beam microinstabilities, the small radial dimension of an EBIS plasma may prevent modes from occurring in EBIS traps due to physical limitation. In EBIS devices with high electron beam compression, where the potential for beam microinstabilities is great, the radial dimension is smaller than the Debye length, which renders plasma kinetic theory invalid. Potential for parametric instabilities exists due to coupling of structure excited modes into plasma modes by various mode-mode coupling ``decay`` processes.

Hershcovitch, A.

1994-05-31

8

Microinstability Studies for the Large Helical Device  

SciTech Connect

Fully kinetic assessments of the stability properties of toroidal drift modes have been obtained for cases for the Large Helical Device (LHD). This calculation employs the comprehensive linear microinstability code FULL, as recently extended for nonaxisymmetric systems. The code retains the important effects in the linearized gyrokinetic equation, using the lowest-order ''ballooning representation'' for high toroidal mode number instabilities in the electrostatic limit. These effects include trapped particles, FLR, transit and bounce and magnetic drift frequency resonances, etc., for any number of plasma species. Results for toroidal drift waves destabilized by trapped electrons and ion temperature gradients are presented, using numerically-calculated three-dimensional MHD equilibria. These are reconstructed from experimental measurements. Quasilinear fluxes of particles and energy for each species are also calculated. Pairs of LHD discharges with different magnetic axis positions and with and without pellet injection are compared.

G. Rewoldt; L.-P. Ku; W.M. Tang; H. Sugama; N. Nakajima; K.Y. Watanabe; S. Murakami; H. Yamada; W.A. Cooper

2002-01-28

9

Microinstability-based model for anomalous thermal confinement in tokamaks  

SciTech Connect

This paper deals with the formulation of microinstability-based thermal transport coefficients (chi/sub j/) for the purpose of modelling anomalous energy confinement properties in tokamak plasmas. Attention is primarily focused on ohmically heated discharges and the associated anomalous electron thermal transport. An appropriate expression for chi/sub e/ is developed which is consistent with reasonable global constraints on the current and electron temperature profiles as well as with the key properties of the kinetic instabilities most likely to be present. Comparisons of confinement scaling trends predicted by this model with the empirical ohmic data base indicate quite favorable agreement. The subject of anomalous ion thermal transport and its implications for high density ohmic discharges and for auxiliary-heated plasmas is also addressed.

Tang, W.M.

1986-03-01

10

Finite-? Split-weight Gyrokinetic Particle Simulation of Microinstabilities  

NASA Astrophysics Data System (ADS)

The finite-? split-weight gyrokinetic particle simulation scheme [1] has been implemented in two-dimensional slab geometry for the purpose of studying the effects of high temperature electrons on microinstabilities. Drift wave instabilities and ion temperature gradient modes are studied in both shearless slab and sheared slab geometries. The linear and nonlinear evolution of these modes, as well as the physics of microtearing, is compared with the results of Reynders [2] and Cummings [3]. [1] W. W. Lee, J. L. V. Lewandowski, T. S. Hahm, and Z. Lin, Phys. Plasmas 8, 4435 (2001). [2] J. V. W. Reynders, Ph.D. thesis, Princeton University (1992). [3] J. C. Cummings, Ph.D. thesis, Princeton University (1995).

Jenkins, Thomas G.; Lee, W. W.; Lewandowski, J. L. V.

2003-10-01

11

Microinstability and internal impingement in overhead athletes.  

PubMed

A complex interplay exists between the static and dynamic stabilizers in the glenohumeral joint, especially in overheard athletes who need a shoulder hypermobile enough to perform overhead activity yet stable enough to prevent joint subluxation. Concomitant shoulder pathologies commonly occur in the setting of microinstability and internal impingement. Before any surgical intervention, a 3- to 6-month course of conservative measures should first be attempted, with exercises focused on rotator cuff and scapular stabilizer strengthening combined with posterior capsule stretching. If surgery is needed, arthroscopic suture plication with treatment of concomitant lesions has been shown to provide the best clinical outcomes. PMID:24079429

Chambers, Lauchlan; Altchek, David W

2013-10-01

12

Collisionless microinstabilities in stellarators. II. Numerical simulations  

SciTech Connect

Microinstabilities exhibit a rich variety of behavior in stellarators due to the many degrees of freedom in the magnetic geometry. It has recently been found that certain stellarators (quasi-isodynamic ones with maximum-J geometry) are partly resilient to trapped-particle instabilities, because fast-bouncing particles tend to extract energy from these modes near marginal stability. In reality, stellarators are never perfectly quasi-isodynamic, and the question thus arises whether they still benefit from enhanced stability. Here, the stability properties of Wendelstein 7-X and a more quasi-isodynamic configuration, QIPC, are investigated numerically and compared with the National Compact Stellarator Experiment and the DIII-D tokamak. In gyrokinetic simulations, performed with the gyrokinetic code GENE in the electrostatic and collisionless approximation, ion-temperature-gradient modes, trapped-electron modes, and mixed-type instabilities are studied. Wendelstein 7-X and QIPC exhibit significantly reduced growth rates for all simulations that include kinetic electrons, and the latter are indeed found to be stabilizing in the energy budget. These results suggest that imperfectly optimized stellarators can retain most of the stabilizing properties predicted for perfect maximum-J configurations.

Proll, J. H. E.; Xanthopoulos, P.; Helander, P. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, 17491 Greifswald, Germany and Max-Planck/Princeton Research Center for Plasma Physics, 17491 Greifswald (Germany)] [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, 17491 Greifswald, Germany and Max-Planck/Princeton Research Center for Plasma Physics, 17491 Greifswald (Germany)

2013-12-15

13

Comparison of Linear Microinstability Calculations of Varying Input Realism  

SciTech Connect

The effect of varying ''input realism'' or varying completeness of the input data for linear microinstability calculations, in particular on the critical value of the ion temperature gradient for the ion temperature gradient mode, is investigated using gyrokinetic and gyrofluid approaches. The calculations show that varying input realism can have a substantial quantitative effect on the results.

G. Rewoldt

2003-09-08

14

Characteristics of microinstabilities in electron cyclotron and ohmic heated discharges  

SciTech Connect

Characteristics of microinstabilities in electron cyclotron (EC) and ohmic heated (OH) discharges in the T10 tokamak have been analyzed by linear electrostatic gyrokinetic simulations with gyro[J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] aiming to find insights into the effect of auxiliary heating on the transport. Trapped electron modes are found to be unstable in both OH and the EC heated scenarios. In the OH case the main drive is from the density gradient and in the EC case from the electron temperature gradient. The growth rates and particle fluxes exhibit qualitatively different scaling with the electron-to-ion temperature ratios in the two cases. This is mainly due to the fact that the dominant drives and the collisionalities are different. The inward flow velocity of impurities and the impurity diffusion coefficient decreases when applying EC heating, which leads to lower impurity peaking, consistently with experimental observations.

Pusztai, I.; Moradi, S.; Fueloep, T. [Department of Applied Physics, Nuclear Engineering, Chalmers University of Technology and Euratom-VR Association, Goeteborg (Sweden); Timchenko, N. [Institute of Tokamak Physics, NRC ''Kurchatov Institute,'' 123182, Kurchatov Sq. 1, Moscow (Russian Federation)

2011-08-15

15

Characteristics of microinstabilities in electron cyclotron and ohmic heated discharges  

NASA Astrophysics Data System (ADS)

Characteristics of microinstabilities in electron cyclotron (EC) and ohmic heated (OH) discharges in the T10 tokamak have been analyzed by linear electrostatic gyrokinetic simulations with gyro [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] aiming to find insights into the effect of auxiliary heating on the transport. Trapped electron modes are found to be unstable in both OH and the EC heated scenarios. In the OH case the main drive is from the density gradient and in the EC case from the electron temperature gradient. The growth rates and particle fluxes exhibit qualitatively different scaling with the electron-to-ion temperature ratios in the two cases. This is mainly due to the fact that the dominant drives and the collisionalities are different. The inward flow velocity of impurities and the impurity diffusion coefficient decreases when applying EC heating, which leads to lower impurity peaking, consistently with experimental observations.

Pusztai, I.; Moradi, S.; Fülöp, T.; Timchenko, N.

2011-08-01

16

Dynamics and microinstabilities at perpendicular collisionless shock: A comparison of large-scale two-dimensional full particle simulations with different ion to electron mass ratio  

E-print Network

Large-scale two-dimensional (2D) full particle-in-cell simulations are carried out for studying the relationship between the dynamics of a perpendicular shock and microinstabilities generated at the shock foot. The structure and dynamics of collisionless shocks are generally determined by Alfven Mach number and plasma beta, while microinstabilities at the shock foot are controlled by the ratio of the upstream bulk velocity to the electron thermal velocity and the ratio of the plasma-to-cyclotron frequency. With a fixed Alfven Mach number and plasma beta, the ratio of the upstream bulk velocity to the electron thermal velocity is given as a function of the ion-to-electron mass ratio. The present 2D full PIC simulations with a relatively low Alfven Mach number (M_A ~ 6) show that the modified two-stream instability is dominant with higher ion-to-electron mass ratios. It is also confirmed that waves propagating downstream are more enhanced at the shock foot near the shock ramp as the mass ratio becomes higher. T...

Umeda, Takayuki; Matsukiyo, Shuichi; Yamazaki, Ryo

2014-01-01

17

A comprehensive gyrokinetic description of global electrostatic microinstabilities in a tokamak  

NASA Astrophysics Data System (ADS)

It is believed that low frequency microinstabilities such as ion temperature gradient (ITG) driven modes and trapped electron modes (TEMs) are largely responsible for the experimentally observed anomalous transport via the ion and electron channels in a tokamak. In the present work, a comprehensive global linear gyrokinetic model incorporating fully kinetic (trapped and passing) electrons and ions, actual ion to electron mass ratio, radial coupling, and profile variation is used to investigate the ITG driven modes and pure TEMs. These modes are found to exhibit multiscale structures in the presence of nonadiabatic passing electrons. The multiscale structure is related to the large nonadiabaticity of electrons in the vicinity of mode rational magnetic surfaces and leads to reduced mixing length estimates of transport compared to those obtained from adiabatic electron models.

Chowdhury, J.; Ganesh, R.; Brunner, S.; Vaclavik, J.; Villard, L.; Angelino, P.

2009-05-01

18

Collisionless microinstabilities in stellarators. I. Analytical theory of trapped-particle modes  

SciTech Connect

This is the first in a series of papers about collisionless, electrostatic micro-instabilities in stellarators, with an emphasis on trapped-particle modes. It is found that, in so-called maximum-J configurations, trapped-particle instabilities are absent in large regions of parameter space. Quasi-isodynamic stellarators have this property (approximately), and the theory predicts that trapped electrons are stabilizing to all eigenmodes with frequencies below the electron bounce frequency. The physical reason is that the bounce-averaged curvature is favorable for all orbits, and that trapped electrons precess in the direction opposite to that in which drift waves propagate, thus precluding wave-particle resonance. These considerations only depend on the electrostatic energy balance and are independent of all geometric properties of the magnetic field other than the maximum-J condition. However, if the aspect ratio is large and the instability phase velocity differs greatly from the electron and ion thermal speeds, it is possible to derive a variational form for the frequency showing that stability prevails in a yet larger part of parameter space than what follows from the energy argument. Collisionless trapped-electron modes should therefore be more stable in quasi-isodynamic stellarators than in tokamaks.

Helander, P.; Proll, J. H. E.; Plunk, G. G. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, 17491 Greifswald (Germany) [Max-Planck-Institut für Plasmaphysik, EURATOM Association, 17491 Greifswald (Germany); Max-Planck/Princeton Research Center for Plasma Physics, 17491 Greifswald (Germany)

2013-12-15

19

Effect of Plasma Shape on Electron Heat Transport in the Presence of Extreme Temperature Gradients Variations in TCV  

Microsoft Academic Search

Electron heat transport experiments are performed in L-mode plasmas at various plasma triangularities, using radially localised electron cyclotron (EC) heating to vary the normalised electron temperature gradient R\\/LTe (where 1\\/LTe= ?Te\\/Te) and the electron temperature Te over an unusually large range. Local gyro-fluid (GLF23) and global collisionless gyro-kinetic (LORB5) linear simulations allow the determination of the unstable micro-instabilities. Ion temperature

A. Pochelon; Y. Camenen; R. Behn; A. Bortolon; A. Bottino; S. Coda; B. P. Duval; E. Fable; T. P. Goodman; M. A. Henderson; A. N. Karpushov; J.-M. Moret; A. Mück; E. Nelson-Melby

20

Comparing Linear Microinstability of the National Compact Stellarator Expriment and a Shaped Tokamak  

SciTech Connect

One metric for comparing con nement properties of di erent magnetic fusion energy con gurations is the linear critical gradient of drift wave modes. The critical gradient scale length determines the ratio of the core to pedestal temperature when a plasma is limited to marginal stability in the plasma core. The gyrokinetic turbulence code GS2 was used to calculate critical temperature gradients for the linear, collisionless ion tem- perature gradient (ITG) mode in the National Compact Stellarator Experiment (NCSX) and a prototypical shaped tokamak, based on the pro les of a JET H-mode shot and the stronger shaping of ARIES-AT. While a concern was that the narrow cross section of NCSX at some toroidal locations would result in steep gradients that drive instabilities more easily, it is found that other stabilizing e ects of the stellarator con guration o set this so that the normalized critical gradients for NCSX are competitive with or even better than for the tokamak. For the adiabatic ITG mode, NCSX and the tokamak had similar critical gradients, though beyond marginal stability, NCSX had larger growth rates. However, for the kinetic ITG mode, NCSX had a higher critical gradient and lower growth rates until a/LT ?#25; 1:5 a/LT;crit, when it surpassed the tokamak's. A discussion of the results presented with respect to a/LT vs R/LT is included.

J.A. Baumgaertel, G.W. Hammett and D.R. Mikkelsen

2012-11-20

21

Instability of a current-carrying finite-beta collisional plasma.  

PubMed

The microinstability of a cross-field current-carrying plasma in which the electron collisions are important on the time scale of the oscillations and can be modeled with a Bhatnagar-Gross-Krook operator is studied using linearized kinetic theory under conditions of finite electron beta. The finiteness of beta allows for coupling between electrostatic and electromagnetic modes and necessitates dealing with the entire dispersion tensor. Fundamental features of the resulting instability are identified and contrasted with those found in previous studies of the lower hybrid current-driven instability in which either collisions or finite-beta effects were neglected. As beta increases, collisions play a more important role in destabilization, alter the character and extent of electromagnetic coupling, shift the instability to more perpendicular modes, and lead to a recapturing of some of the fluidlike properties the modes have in the electrostatic limit in contrast with their highly kinetic character in the collisionless limit. PMID:11736288

Choueiri, E Y

2001-12-01

22

Quasilinear carbon transport in an impurity hole plasma in LHD  

NASA Astrophysics Data System (ADS)

Comprehensive electrostatic gyrokinetic linear stability calculations for ion-scale microinstabilities in an LHD plasma with an ion-internal transport barrier (ITB) and carbon "impurity hole" are used to make quasilinear estimates of particle flux to explore whether microturbulence can explain the observed outward carbon fluxes that flow "up" the impurity density gradient. The ion temperature is not stationary in the ion-ITB phase of the simulated discharge, during which the core carbon density decreases continuously. To fully sample these varying conditions, the calculations are carried out at three radial locations and four times. The plasma parameter inputs are based on experimentally measured profiles of electron and ion temperature, as well as electron and carbon density. The spectroscopic line-average ratio of hydrogen and helium densities is used to set the density of these species. Three ion species (H,He,C) and the electrons are treated kinetically, including collisions. Electron instability drive does enhance the growth rate significantly, but the most unstable modes have characteristics of ion temperature gradient modes in all cases. As the carbon density gradient is scanned between the measured value and zero, the quasilinear carbon flux is invariably inward when the carbon density profile is hollow, so turbulent transport due to the instabilities considered here does not explain the observed outward flux of impurities in impurity hole plasmas. The stiffness of the quasilinear ion heat flux is found to be 1.7-2.3, which is lower than several estimates in tokamaks.

Mikkelsen, D. R.; Tanaka, K.; Nunami, M.; Watanabe, T.-H.; Sugama, H.; Yoshinuma, M.; Ida, K.; Suzuki, Y.; Goto, M.; Morita, S.; Wieland, B.; Yamada, I.; Yasuhara, R.; Tokuzawa, T.; Akiyama, T.; Pablant, N. A.

2014-08-01

23

Finite beta effects on the drift-cyclotron instability. [pressure ratio in plasma pinch  

NASA Technical Reports Server (NTRS)

The effects of finite plasma beta and strong plasma inhomogeneities on the microinstability resulting from the unstable coupling of ion-cyclotron oscillations and an ion drift wave are examined. A local electromagnetic, kinetic dispersion equation, which takes into account finite orbit modifications of both ions and electrons as well as the effects of strong inhomogeneities on the ions and permits the continuous tracking of the instability from the weak gradient regime to the strong gradient regime, is derived and solved numerically. Finite beta is shown to increase the frequency and reduce the growth rate of the instability, but not completely stabilize it due to electromagnetic effects. When plasma inhomogeneity is sufficiently strong, finite beta reduces the growth rate of the large k sub y band of a given harmonic more than the small k sub y band; however, the most unstable bands remain the same as in the case of zero beta. Implications of these results for the Tandem Mirror Experiment are discussed.

Gladd, N. T.; Huba, J. D.

1979-01-01

24

Models of magnetic field evolution and effective viscosity in weakly collisional extragalactic plasmas  

NASA Astrophysics Data System (ADS)

In weakly collisional plasmas such as the intracluster medium (ICM), the viscous stress and the rate of change of the magnetic energy are proportional to the local pressure anisotropy, so subject to constraints imposed by the pressure-anisotropy-driven microinstabilities (mirror and firehose) and controlled by the local instantaneous plasma ?. The dynamics of such plasmas can be dramatically different from a conventional magnetohydrodynamic fluid. The plasma is expected to stay locally marginal with respect to the instabilities, but how it does this remains an open question. Two models of magnetic field evolution are investigated. In the first, marginality is achieved via suppression of the rate of change of the field. In the second, the instabilities give rise to anomalous collisionality, reducing pressure anisotropy to marginal - at the same time decreasing viscosity and so increasing the turbulent rate of strain. Implications of these two models are studied in a simplified zero-dimensional setting. In the first model, the field grows explosively but on a time-scale that scales with the initial ?, while in the second, dynamical field strength can be reached in one large-scale turbulence turnover time regardless of the initial seed. Both models produce very intermittent fields. Both also suffer from fairly strong constraints on their applicability: for typical cluster-core conditions, scale separation between the fluid motions (with account of suppressed viscous stress) and the miscoscale fluctuations break down at ? ˜ 104-105. At larger ? (weaker fields), a fully collisionless plasma dynamo theory is needed to justify field growth from a tiny primordial seed. However, the models discussed here are appropriate for studying the structure of the currently observed field as well as large-scale dynamics and thermodynamics of the magnetized ICM or similarly dilute astrophysical plasmas.

Mogavero, Federico; Schekochihin, Alexander A.

2014-06-01

25

Improved Confinement in Impurity-Seeded Plasmas in JT-60U and TFTR  

NASA Astrophysics Data System (ADS)

Improved energy confinement in impurity-seeded plasmas has been observed on several tokamaks, offering the possibility of high confinement at high density and reduced power to the wall. We analyze and compare impurity-seeded plasmas in TFTR and JT-60U, with a goal of understanding the improved confinement. In JT-60U ELMy H-modes with Ar puffing at n_e^GW = 0.7, H = 1.4 has been achieved, about 40% higher than with D2 puffing alone. In TFTR supershots at NBI power Pb ~ 16 MW, \\chii and \\chi_? decreased with Kr and Xe puffing; the ITG mode was stabilized by Kr puffing. At high power (Pb > 28 MW) with Kr injection, confinement and fusion power were improved, and carbon blooms were eliminated. Analysis includes thermal transport by the TRANSP and TOPICS codes, microinstability predictions by FULL and GS2, E× B shearing rate by TRV, and impurity transport and radiated power distributions by MIST and IMPACT.

Hill, K. W.; Ernst, D. R.; Park, H. K.; Rewoldt, G.; Synakowski, E. J.; Taylor, G.; Bush, C. E.; Asakura, N.; Kubo, H.; Sakurai, S.; Itami, K.; Tamai, H.; Konoshima, S.; Higashijima, S.; Shimizu, K.; Shirai, H.; JT-60u Team

2000-10-01

26

Numerical simulation of non-equilibrium plasma flow in a cylindrical MPD thruster using a high-order flux-difference splitting method  

NASA Astrophysics Data System (ADS)

A two-dimensional axisymmetric computational algorithm is developed to simulate the plasma flow field in a self-field MPD thruster, in order to determine the flow behavior and the electromagnetic characteristics distribution. The convective flux vector is computed by using Roe's scheme in combination with Powell's eigensystem technique, and a new modified MUSCL technique called OMUSCL2 is employed to obtain the stable high-accuracy solution. Madrane-Tadmor entropy correction is used to prevent unrealistic expansion shocks near the electrodes tips. To accurately capture the physics of plasma in the system, different physical-chemical sub-models including multi-level non-equilibrium ionization model, generalized Ohm's law for partially ionized plasma, micro-instabilities effects, two-temperature model, and a real equation of state are considered. Numerical results of plasma flow simulation in a cylindrical lab-scale thruster, with mass flow rate of 6 g/s and total discharge current of 8 kA, are presented and comparison with experimental data shows good agreement between the predicted and measured contours of enclosed current and electric potential. The estimated thrust is 16.34 N which exhibits less than 5% difference compared with measured value. Furthermore, this simulation properly predicts the experimentally observed argon jet structure.

Ahangar, Mahdy; Ebrahimi, Reza; Shams, Mehrzad

2014-10-01

27

Plasma jets and plasma bullets  

Microsoft Academic Search

Plasma plumes, or plasma jets, belong to a large family of gas discharges whereby the discharge plasma is extended beyond the plasma generation region into the surrounding ambience, either by a field (e.g. electromagnetic, convective gas flow, or shock wave) or a gradient of a directionless physical quantity (e.g. particle density, pressure, or temperature). This physical extension of a plasma

M G Kong; B N Ganguly; R F Hicks

2012-01-01

28

Plasma Medicine  

NASA Astrophysics Data System (ADS)

Foreword R. Satava and R. J. Barker; Part I. Introduction to Non-equilibrium Plasma, Cell Biology, and Contamination: 1. Introduction M. Laroussi; 2. Fundamentals of non-equilibrium plasmas M. Kushner and M. Kong; 3. Non-equilibrium plasma sources M. Laroussi and M. Kong; 4. Basic cell biology L. Greene and G. Shama; 5. Contamination G. Shama and B. Ahlfeld; Part II. Plasma Biology and Plasma Medicine: 6. Common healthcare challenges G. Isbary and W. Stolz; 7. Plasma decontamination of surfaces M. Kong and M. Laroussi; 8. Plasma decontamination of gases and liquids A. Fridman; 9. Plasma-cell interaction: prokaryotes M. Laroussi and M. Kong; 10. Plasma-cell interaction: eukaryotes G. Isbary, G. Morfill and W. Stolz; 11. Plasma based wound healing G. Isbary, G. Morfill and W. Stolz; 12. Plasma ablation, surgery, and dental applications K. Stalder, J. Woloszko, S. Kalghatgi, G. McCombs, M. Darby and M. Laroussi; Index.

Laroussi, M.; Kong, M. G.; Morfill, G.; Stolz, W.

2012-05-01

29

Plasma universe  

NSDL National Science Digital Library

This single-page reading underlines how abundant plasmas are in the universe. The reading, which is the final page in a tutorial about the plasma phase of matter, points out that understanding plasma is central to understanding what happens in the universe. Through space technologies, researchers have been able to study plasmas in areas like those shown in the images that illustrate this reading. One of the images shows plasma loops on the Sun. Copyright 2005 Eisenhower National Clearinghouse

Institute, Space S.

2005-01-01

30

Cosmic plasma  

NASA Technical Reports Server (NTRS)

Attention is given to experimental and theoretical approaches to plasma physics, plasma phenomena in laboratory and space, field and particle aspects of plasmas, the present state of the classical theory, boundary conditions and circuit dependence, and cosmology. Electric currents in space plasmas are considered, taking into account dualism in physics, particle-related phenomena in plasma physics, magnetic field lines, filaments, local plasma properties and the circuit, electric double layers, field-aligned currents as 'cables', an expanding circuit, different types of plasma regions, the cellular structure of space, and the fine structure of active plasma regions. Other topics discussed are related to circuits, the theory of cosmic plasmas, the origin of the solar system, the coexistence of matter and antimatter, annihilation as a source of energy, the Hubble expansion in a Euclidean space, and a model for the evolution of the Metagalaxy.

Alfven, H.

1981-01-01

31

Plasma Physics  

Microsoft Academic Search

Beginning at an introductory level, this text presents a thorough treatment of plasma physics, including an extensive discussion of its applications in thermonuclear fusion research. A novel feature of this book is its comprehensive description of the various concepts and formulas widely used in fusion theory based on the fundamental equations of the plasma fluid. The physics of fusion plasmas

Kyoji Nishikawa; Masashiro Wakatani

1990-01-01

32

Amazing plasmas  

NSDL National Science Digital Library

A space weather site offers this tutorial about the state of matter called plasma. Animations, two games, and numerous enlargeable graphics are included in the tutorial. It presents information about what plasma is and where it is naturally found. The tutorial explains that understanding plasma and how it interacts with electric and magnetic fields is central to understanding much about our universe. In addition, one section of the tutorial discusses experimental fusion reactors in which man-made plasmas are used on earth. Plasma is the main type of matter in the universe, but it rarely occurs naturally on Earth because of the world's relatively cool temperatures. Copyright 2005 Eisenhower National Clearinghouse

Institute, Space S.

2005-01-01

33

Dusty plasmas  

SciTech Connect

This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project has been to develop a fundamental understanding of dusty plasmas at the Laboratory. While dusty plasmas are found in space in galactic clouds, planetary rings, and cometary tails, and as contaminants in plasma enhanced fabrication of microelectronics, many of their properties are only partially understood. Our work has involved both theoretical analysis and self-consistent plasma simulations to understand basic properties of dusty plasmas related to equilibrium, stability, and transport. Such an understanding can improve the control and elimination of plasma dust in industrial applications and may be important in the study of planetary rings and comet dust tails. We have applied our techniques to the study of charging, dynamics, and coagulation of contaminants in plasma processing reactors for industrial etching and deposition processes and to instabilities in planetary rings and other space plasma environments. The work performed in this project has application to plasma kinetics, transport, and other classical elementary processes in plasmas as well as to plasma waves, oscillations, and instabilities.

Jones, M.E.; Winske, D.; Keinigs, R.; Lemons, D.

1996-05-01

34

Earth plasmas  

NSDL National Science Digital Library

Fusion is the focus of this section of a tutorial about plasma, one of the four states of matter. This section deals with plasmas on Earth. There is little naturally-occurring plasma here because of the Earth's relatively cool (by universe standards) temperature, but human-made plasma is produced for industry and research purposes. The section explores the use of plasmas in experimental fusion reactors, pointing out three categories of significant unresolved issues that stand in the way of fusion becoming a viable energy source. The use of electromagnets to confine plasmas is discussed. Enlargeable images of fusion reactors are provided, and an explanation of the difference between fission and fusion is supplemented by animations of the two reaction types. Copyright 2005 Eisenhower National Clearinghouse

Institute, Space S.

2005-01-01

35

Plasma Cell Disorders  

MedlinePLUS

... Blood Disorders > Plasma Cell Disorders 4 Overview of Plasma Cell Disorders (Dysproteinemias; Monoclonal Gammopathies; Paraproteinemias; Plasma Cell Dyscrasias) Plasma cell disorders are uncommon. They ...

36

Thermal plasmas  

Microsoft Academic Search

Although many thermal plasma processes have been developed for industrial applications, the wide acceptance as a manufacturing technology is prevented due to economical and competitive reasons, and\\/or reproducibility and reliability aspects. This paper is devoted to an assessment of the present knowledge in the following topics: (1) plasma torch and performance of blown arc (dc or ac), transferred arc and

P. Fauchais; A. Vardelle

1997-01-01

37

Plasma valve  

DOEpatents

A plasma valve includes a confinement channel and primary anode and cathode disposed therein. An ignition cathode is disposed adjacent the primary cathode. Power supplies are joined to the cathodes and anode for rapidly igniting and maintaining a plasma in the channel for preventing leakage of atmospheric pressure through the channel.

Hershcovitch, Ady (Mount Sinai, NY); Sharma, Sushil (Hinsdale, IL); Noonan, John (Naperville, IL); Rotela, Elbio (Clarendon Hills, IL); Khounsary, Ali (Hinsdale, IL)

2003-01-01

38

Plasma accelerator  

DOEpatents

There has been invented an apparatus for acceleration of a plasma having coaxially positioned, constant diameter, cylindrical electrodes which are modified to converge (for a positive polarity inner electrode and a negatively charged outer electrode) at the plasma output end of the annulus between the electrodes to achieve improved particle flux per unit of power.

Wang, Zhehui (Los Alamos, NM); Barnes, Cris W. (Santa Fe, NM)

2002-01-01

39

Plasma universe  

NASA Technical Reports Server (NTRS)

Traditionally the views on the cosmic environent have been based on observations in the visual octave of the electromagnetic spectrum, during the last half-century supplemented by infrared and radio observations. Space research has opened the full spectrum. Of special importance are the X-ray-gamma-ray regions, in which a number of unexpected phenomena have been discovered. Radiations in these regions are likely to originate mainly from magnetised cosmic plasmas. Such a medium may also emit synchrotron radiation which is observable in the radio region. If a model of the universe is based on the plasma phenomena mentioned it is found that the plasma universe is drastically different from the traditional visual universe. Information about the plasma universe can also be obtained by extrapolation of laboratory experiments and magnetospheric in situ measurements of plasmas. This approach is possible because it is likely that the basic properties of plasmas are the same everywhere. In order to test the usefulness of the plasma universe model it is applied to cosmogony. Such an approach seems to be rather successful. For example, the complicated structure of the Saturnian C ring can be accounted for. It is possible to reconstruct certain phenomena 4 to 5 billions of years ago with an accuracy of better than 1%.

Alfven, H.

1986-01-01

40

Plasma Rain  

NASA Video Gallery

On April 19, 2010 AIA observed one of the largest prominence eruptions in years. The huge structure erupts, but a great deal of the plasma (hundreds of millions of tons) is unable to escape the gra...

41

Plasma Anodization.  

National Technical Information Service (NTIS)

The process of plasma anodization has been investigated using two systems. The first was a cold cathode dc discharge system (replacing apparatus described in our earlier reports) with automated ellipsometry to continuously follow the growth of the oxide. ...

D. L. Pulfrey, G. Olive, L. Young

1972-01-01

42

Plasma physics for physicists  

Microsoft Academic Search

The physics of high-temperature plasmas are presented as a division of contemporary physics for physicists dealing with plasma phenomena outside characteristic plasma physics. Plasmas not in the presence of a magnetic field are treated, with attention given to plasma oscillations, particle collisions, transport phenomena, plasmas in high-frequency fields, the propagation of electromagnetic waves in a plasma, kinetic and hydrodynamic descriptions,

L. A. Artsimovich; R. Z. Sagdeev

1979-01-01

43

TFTR plasma feedback systems  

Microsoft Academic Search

The Tokamak Fusion Test Reactor employs feedback control systems for four plasma parameters, i.e. for plasma current, for plasma major radius, for plasma vertical position, and for plasma density. The plasma current is controlled by adjusting the rate of change of current in the Ohmic Heating (OH) coil system. Plasma current is continuously sensed by a Rogowski coil and its

P. Efthimion; R. J. Hawryluk; W. Hojsak; R. J. Marsala; D. Mueller; W. Rauch; G. D. Tait; G. Taylor; M. Thompson

1985-01-01

44

Plasma Physics  

NSDL National Science Digital Library

This is a PDF version of lecture slides by Dr. Philip D. Rack (Assistant Professor, Department of Materials Science and Engineering at the University of Tennessee in Knoxville) that discuss information from the silicon's crystal structure to how to make doped semiconductors and the mechanics. Although the slides were written by Dr. Rack when he taught at the Rochester Institute of Technology, they are currently hosted by him at the University of Tennessee. Slide topics include plasma properties, DC glow discharge, ionization, plasma species, magnetrons, collisions, and chemical reactions. Numerous mathematical formulas are also presented.

Rack, Philip D.

2012-12-12

45

Current-Driven Plasma Acceleration Versus Current-Driven Energy Dissipation  

E-print Network

- terizing the current-driven microinstabilities behind the turbulent dissipation degrading the efficiency the electrostatic assumption and none have been directly compared to wave experiments. Our approach to the problem. Second is an engineering pro- gram in which these transport models are coupled to the flow through self

Choueiri, Edgar

46

Plasma technology  

SciTech Connect

This paper describes the uses of plasma technology for the thermal destruction of hazardous wastes such as PCBs, dioxins, hydrocarbons, military chemicals and biological materials; for metals recovery from steel making dusts. One advantage of the process is that destruction of wastes can be carried out on site. Systems in several countries use the excess thermal energy for district heating.

Herlitz, H.G.

1986-11-01

47

Properties of large scale plasma flow during the early stage of the plasmaspheric refilling  

NASA Technical Reports Server (NTRS)

The objective is to better characterize the macroscopic properties of the interhemisphere plasma flow by solving a more complete set of hydrodynamic equations than that solved previously. Specifically, the ion continuity, momentum and energy equations were solved for the plasma flow along the closed magnetic field lines. During the initial stage of the supersonic outflow in the equatorial region, the ions cool substantially. Using the hydrodynamic model for the large-scale plasma flow, the dynamics of shocks was examined which form in the geomagnetic flux tubes during the early stages of refilling. These shocks are more like those forming in neutral gases than the electrostatic shocks driven by microinstabilities involving ion-ion interaction. Therefore, the shocks seen in the hydrodynamic model are termed as hydrodynamic shocks. Such shocks are generally unsteady and therefore the usual shock jump conditions given by Rankine-Hugoniot relations are not strictly applicable to them. The density, flow velocity and temperature structures associated with the shocks are examined for both asymmetrical and symmetrical flows. In the asymmetrical flow the outflow from one of two conjugate ionospheres is dominant. On the other hand, in the symmetrical case outflows from the two ionospheric sources are identical. Both cases are treated by a two-stream model. In the late type of flow, the early-time refilling shows a relaxation type of oscillation, which is driven by the large-scale interactions between the two identical streams. After this early stage, the resulting temperature structure shows some interesting features. In the equatorial region the streams are isothermal, but in the off-equatorial regions the streams have quite different temperatures, and also densities and flow velocities. The dense and slow stream is found to be warmer than the low-density fast stream. In the late stage of refilling, the temperature is found to steadily increase from the conjugate ionospheres towards the equator; the equatorial temperature is found to be as high as about 8000 K compared to the ionospheric temperature of 3600 K.

Singh, Nagendra; Craven, P.; Torr, D. G.; Richards, P. G.

1990-01-01

48

Applications of atmospheric plasmas  

Microsoft Academic Search

Surface modification techniques using plasmas have historically been completed in a low pressure environment due to Pd (pressure x gap distance) considerations influencing the behavior of plasma generation. Generally, plasmas produced in a low pressure environment are of a non-thermal or cold nature. The basic feature of non-thermal plasmas is the majority of electrical energy used to generate the plasma

Christopher John Oldham

2009-01-01

49

Improved plasma accelerator  

NASA Technical Reports Server (NTRS)

Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

Cheng, D. Y.

1971-01-01

50

The Pervasive Plasma State  

NSDL National Science Digital Library

This site by the Division of Plasma Physics of the American Physical Society explores plasma, a state of matter that blankets the Earth as a result of solar winds. Pictures and text are used to convey the significance and commonplace use of plasmas in society. Information provided by the site includes understanding plasmas, commercial applications, plasma in space, the future of plasma use, and more.

Berk, Herbert L.

2008-05-06

51

The Pervasive Plasma State  

NSDL National Science Digital Library

This site by the Division of Plasma Physics of the American Physical Society explores plasma, a state of matter that blankets the Earth as a result of solar winds. Pictures and text are used to convey the significance and commonplace use of plasmas in society. Information provided by the site includes understanding plasmas, commercial applications, plasma in space, the future of plasma use, and more.

2006-07-14

52

Applications of atmospheric plasmas  

NASA Astrophysics Data System (ADS)

Surface modification techniques using plasmas have historically been completed in a low pressure environment due to Pd (pressure x gap distance) considerations influencing the behavior of plasma generation. Generally, plasmas produced in a low pressure environment are of a non-thermal or cold nature. The basic feature of non-thermal plasmas is the majority of electrical energy used to generate the plasma is primarily used to produce energetic electrons for generating chemical species. Low pressure plasmas serve many purposes for materials processing. Since the plasma environment is contained within a closed vessel, the plasma can be controlled very easily. Low pressure plasmas have been used in many industries but the complexity associated with the large pumping stations and limitation to batch processing has motivated new work in the area of atmospheric plasmas. Atmospheric plasmas offer both economic and technical justification for use over low pressure plasmas. Since atmospheric plasmas can be operated at ambient conditions, lower costs associated with continuous processing and a decrease in the complexity of equipment validate atmospheric plasma processing as a next generation plasma-aided manufacturing process. In an effort to advance acceptance of atmospheric plasma processing into industry, a process was developed, the dielectric barrier discharge (DBD), in order to generate a homogeneous and non-thermal plasma discharge at ambient conditions. The discharge was applied to the reduction of known food borne pathogens, deposition of thin film materials, and modification of lignocellulosic biomass.

Oldham, Christopher John

53

Communication through plasma sheaths  

SciTech Connect

We wish to transmit messages to and from a hypersonic vehicle around which a plasma sheath has formed. For long distance transmission, the signal carrying these messages must be necessarily low frequency, typically 2 GHz, to which the plasma sheath is opaque. The idea is to use the plasma properties to make the plasma sheath appear transparent.

Korotkevich, A. O.; Newell, A. C.; Zakharov, V. E. [Landau Institute for Theoretical Physics RAS, 2, Kosygin Str., Moscow, 119334 (Russian Federation); Department of Mathematics, University of Arizona, 617 N. Santa Rita Ave., Tucson, Arizona 85721 (United States); Department of Mathematics, University of Arizona, 617 N. Santa Rita Ave., Tucson, Arizona 85721 (United States); Lebedev Physical Institute RAS, 53, Leninsky Prosp., GSP-1 Moscow, 119991 (Russian Federation); Landau Institute for Theoretical Physics RAS, 2, Kosygin Str., Moscow, 119334 (Russian Federation) and Waves and Solitons LLC, 918 W. Windsong Dr., Phoenix, Arizona 85045 (United States)

2007-10-15

54

Dust-Plasma  

SciTech Connect

Our theoretical research on dust-plasma interactions has concentrated on three main areas: a)studies of grain charging and applications; b) waves and instabilities in weakly correlated dusty plasma with applications to space and laboratory plasmas; c) waves in strongly coupled dusty plasmas.

Marelene Rosenberg

2005-02-22

55

Thermal plasma processing  

Microsoft Academic Search

A review is given of the fundamental aspects involved in material processing using thermal plasma technology. The description of plasma generating devices covers DC plasma torches, DC transferred arcs, RF inductively coupled plasma torches and hybrid combinations of them. Emphasis is given to the identification of the basic energy coupling mechanism in each case and the principal characteristics of the

Maher I. Boulos

1991-01-01

56

Coalition for Plasma Science  

NSDL National Science Digital Library

The Coalition for Plasma Science is dedicated to increasing public awareness and understanding of plasma science and its many applications and benefits for society. The site presents a basic desctiption of plasma and some of its applications, along with a teacher's guide to plasma science.

Science, Coalition F.

2003-10-10

57

Plasma sweeper. [Patents  

DOEpatents

A device is described for coupling RF power (a plasma sweeper) from RF power introducing means to a plasma having a magnetic field associated therewith comprises at least one electrode positioned near the plasma and near the RF power introducing means. Means are described for generating a static electric field at the electrode directed into the plasma and having a component substantially perpendicular to the plasma magnetic field such that a non-zero vector cross-product of the electric and magnetic fields exerts a force on the plasma causing the plasma to drift.

Motley, R.W.; Glanz, J.

1982-10-25

58

Plasmas for space propulsion  

NASA Astrophysics Data System (ADS)

Plasma thrusters are challenging the monopoly of chemical thrusters in space propulsion. The specific energy that can be deposited into a plasma beam is orders of magnitude larger than the specific chemical energy of known fuels. Plasma thrusters constitute a vast family of devices ranging from already commercial thrusters to incipient laboratory prototypes. Figures of merit in plasma propulsion are discussed. Plasma processes and conditions differ widely from one thruster to another, with the pre-eminence of magnetized, weakly collisional plasmas. Energy is imparted to the plasma via either energetic electron injection, biased electrodes or electromagnetic irradiation. Plasma acceleration can be electrothermal, electrostatic or electromagnetic. Plasma-wall interaction affects energy deposition and erosion of thruster elements, and thus is central for thruster efficiency and lifetime. Magnetic confinement and magnetic nozzles are present in several devices. Oscillations and turbulent transport are intrinsic to the performances of some thrusters. Several thrusters are selected in order to discuss these relevant plasma phenomena.

Ahedo, Eduardo

2011-12-01

59

Plasma Physics PART Al: INTRODUCTION TO PLASMA SCIENCE  

E-print Network

Plasma Physics PART Al: INTRODUCTION TO PLASMA SCIENCE I. What is a plasma? 1 II. Plasma fundamentals 3 1. Quasineutrality and Debye length 2. Plasma frequency and acoustic velocity 3. Larmor radius; magnetic buckets Cross section data 21 PART A3: PLASMA SOURCES I IV. Introduction to plasma sources 25 1

Chen, Francis F.

60

Plasma radio emission from inhomogeneous collisional plasma  

NASA Astrophysics Data System (ADS)

We consider the production of radio waves via plasma emission involving Langmuir waves from a flare-accelerated electron beam in a dense plasma with density perturbations. We numerically solve the system of nonlinear kinetic equations for the particles, Langmuir waves and electromagnetic waves. We include the effects of collisions on electrons and waves, and of random fluctuations in the plasma density on Langmuir waves. We follow the temporal evolution of the system, and obtain an estimate of the radio emission produced.

Ratcliffe, Heather

2011-07-01

61

Plasma surface cleaning using microwave plasmas  

SciTech Connect

In a microwave electron cyclotron resonance (ECR) plasma source, reactive plasmas of oxygen and its mixture with argon are used for plasma-cleaning experiments. Aluminum test samples (0.95 {times} 1.9 cm) were coated with thin films ({le} 20 {mu}m in thickness) of Shell Vitrea oil and cleaned by using such reactive plasmas. The plasma cleaning was done in various discharge conditions with fixed microwave power, rf power, biased potential, gas pressures (0.5 and 5 mtorr), and operating time up to 35 min. The status of plasma cleaning has been monitored by using mass spectroscopy. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured clean rates of low pressure (0.5 mtorr) argon/oxygen plasmas were as high as 2.7 {mu}/min. X-ray photoelectron spectroscopy was used to determine cleanliness of the sample surfaces and confirm the effectiveness of plasma cleaning in achieving atomic levels of surface cleanliness. In this paper, significant results are reported and discussed.

Tsai, C.C.; Haselton, H.H.; Nelson, W.D.; Schechter, D.E. [Oak Ridge National Lab., TN (United States); Thompson, L.M.; Campbell, V.B.; Glover, A.L.; Googin, J.M. [Oak Ridge Y-12 Plant, TN (United States)

1993-11-01

62

Beams and Plasmas  

NASA Astrophysics Data System (ADS)

The long term goal of the Cooler Experiment-30 plasma trap is for its use as a target in the Indiana University Cyclotron Facility Storage Ring. Before it can be used as a target, the trap must be able to contain a stable and dense plasma. The implement ation of the current trap design facilitated the observation of several properties of electron plasmas in the trap. These properties include the number of electrons in the trap, radius of the plasma, temperature of the plasma, ionization of hydrogen in t he trap, and the charge density wave properties of the plasma.

Gerberich, Heather

1996-11-01

63

Plasma Free Metanephrines  

MedlinePLUS

... of this website will be limited. Search Help? Plasma Free Metanephrines Share this page: Was this page ... Back to top 2. Does the amount of plasma free metanephrines detected correspond to the size of ...

64

Plasma amino acids  

MedlinePLUS

Plasma amino acids is a screening test done on infants that looks at the amounts of amino ... Laboratory error High or low amounts of individual plasma amino acids must be considered with other information. ...

65

Dusty Plasma Laboratory  

NSDL National Science Digital Library

The DPL studies micron size solid objects immersed in a plasma consisting of electrons, ions, and neutrals. A description of experiments and applications is provided in addition to a list of online plasma research resources.

Spann, James

2003-10-10

66

Laser plasma interaction  

Microsoft Academic Search

Two topics are reviewed: laser generation of homogeneous plasmas with prescribed density and laser induced high amplitude electron plasma waves. A special emphasis is put on various forms of stimulated Raman scattering. Applications to elementary particle acceleration are discussed.

J L Bobin

1990-01-01

67

Plasma processes in space  

NASA Technical Reports Server (NTRS)

Elementary microscopic interactions in plasmas are described. The importance of plasma physics in space studies is illustrated by examining several phenomena which cannot be explained satisfactorily by MHD theory. These include kinetic instabilities, plasma turbulence in the bow shock, magnetic turbulence near the moon, VLF emissions in the magnetosphere, planetary and solar radio emissions, and interaction of planetary and cometary plasmas with the solar wind. Evidence for the existence of anomalous transport processes in terrestrial and planetary magnetospheres is presented.

Wu, C. S.

1976-01-01

68

Basic plasma physics II  

Microsoft Academic Search

The basic physics of classical ideal plasmas is presented in reviews of recent theoretical and experimental investigations, with an emphasis on nonlinear interactions violating the assumptions of weak turbulence. Topics examined include Kolmogorov spectra, parametric instabilities in magnetoactive plasmas, collapse and self-focusing of Langmuir waves, collective dissipation and transport, spontaneous reconnection of magnetic-field lines in a collisionless plasma, collective-beam\\/plasma interaction,

A. A. Galeev; R. N. Sudan

1984-01-01

69

Plasma kinetics in molecular plasmas and modeling of reentry plasmas  

NASA Astrophysics Data System (ADS)

State-to-state non-equilibrium plasma kinetics is widely used to characterize cold molecular and reentry plasmas. The approach requires a high level of dynamical information, and demands a large effort in the creation of complete databases of state-resolved cross sections and rate coefficients. Recent results, emphasizing the dependence of elementary process probability on both the vibrational and rotational energy content of the H2 molecule, are presented for those channels governing the microscopic collisional dynamics in non-equilibrium plasmas, i.e. electron-impact induced resonant processes, vibrational deactivation and dissociation in atom-diatom collisions and atomic recombination at the surface. Results for H2 plasmas, i.e. negative ion sources for neutral beam injection in fusion reactors, RF parallel-plate reactors for microelectronics, atmospheric discharges and the shock wave formed in the hypersonic entry of vehicles in planetary atmosphere for aerothermodynamics, are discussed.

Capitelli, M.; Celiberto, R.; Colonna, G.; D'Ammando, G.; De Pascale, O.; Diomede, P.; Esposito, F.; Gorse, C.; Laricchiuta, A.; Longo, S.; Pietanza, L. D.; Taccogna, F.

2011-12-01

70

Aerospatiale industrial thermal plasma activities  

Microsoft Academic Search

Details of nontransferred arc torches, plasma systems in industrial use and operational plasma applications are listed. A plasma application on a foundry cupola is detailed. The setting up of a plasma system is described. Research and development activities are summarized.

Maxime Labrot

1991-01-01

71

Aerospatiale industrial thermal plasma activities  

NASA Astrophysics Data System (ADS)

Details of nontransferred arc torches, plasma systems in industrial use and operational plasma applications are listed. A plasma application on a foundry cupola is detailed. The setting up of a plasma system is described. Research and development activities are summarized.

Labrot, Maxime

72

Aerospatiale Industrial Thermal Plasma Activities.  

National Technical Information Service (NTIS)

Details of nontransferred arc torches, plasma systems in industrial use and operational plasma applications are listed. A plasma application on a foundry cupola is detailed. The setting up of a plasma system is described. Research and development activiti...

M. Labrot

1991-01-01

73

Basic plasma physics I  

Microsoft Academic Search

This book is the result of a decision of a Soviet publishing house and a Dutch publishing company to publish jointly a handbook of plasma physics, in both Russian and English. The first two volumes are devoted to fundamental plasma physics, while subsequent volumes are to be concerned with more specialized topics, such as space plasma physics, thermonuclear fusion, and

A. A. Galeev; R. N. Sudan

1983-01-01

74

Fundamentals of Plasma Physics  

E-print Network

Fundamentals of Plasma Physics James D. Callen University of Wisconsin, Madison June 28, 2006 #12;PREFACE Plasma physics is a relatively new branch of physics that became a mature science over the last-dimensional (three real plus three velocity space coordinates) phase space. Increased understanding of plasma physics

Callen, James D.

75

Optically thick plasmas  

Microsoft Academic Search

Experimental evidence is presented to show that plasmas are often ; optically thick. Data are included on the absorption and emission spectra of Ar ; and N plasmas produced in a plasmajet torch. These plasmas were found to be ; optically thin only at wavelengths shonter than 0.65 . (J.R.D.);

R. Tourin

1963-01-01

76

Thermionic energy conversion plasmas  

Microsoft Academic Search

The author provides a perspective of the nature and scientific characterization of the unique plasmas occurring in the various modes of thermionic converter operation associated with different application requirements. The basic plasma types associated with various modes of converter operation are described, with emphasis on identification and semi-quantitative characterization of the dominant physical processes and utility of each plasma type.

Ned S. Rasor

1991-01-01

77

Perspectives on Plasma  

NSDL National Science Digital Library

Originally conceived and launched by consultant and Senior Research Associate Dr. Timothy E. Eastman at the Space Science Institute in Boulder, Colorado, the Perspectives on Plasma Web site represents all aspects of plasma science and technology. Visitors can explore the basics of plasma, its applications, view a photo gallery, and much more.

Eastman, Timothy E.

1999-01-01

78

Plasmas for Welding  

NSDL National Science Digital Library

To learn about an important plasma used in manufacturing, visit MIT's Plasmas for Welding. The text describes the arc, which is a plasma, and explains how the arc and the metal to be welded are part of an electric circuit. With photos, the site shows how high-power welding machines cut openings in large sheets of metal.

2006-08-05

79

Perspectives on Plasmas  

NSDL National Science Digital Library

Originally conceived and launched by consultant and Senior Research Associate Dr. Timothy E. Eastman at the Space Science Institute in Boulder, Colorado, the Perspectives on Plasma Web site represents all aspects of plasma science and technology. Visitors can explore the basics of plasma, its applications; view a photo gallery, and much more.

Eastman, Timothy E.

2003-10-10

80

Experiments with Plasma Rings  

Microsoft Academic Search

THE use of a coaxial plasma gun with radial magnetic field for the production of magnetized plasma rings was suggested1 by H. Alfvén in 1958. Experiments with a plasma gun of that type were started in the spring of 1958 and a detailed report is to be published2. We present here some new results obtained during continued experiments with a

L. Lindberg; E. Witalis; C. T. Jacobsen

1960-01-01

81

Plasma and magnetospheric research  

NASA Technical Reports Server (NTRS)

Research activities on the following topics were summarized: (1) software for the Space Plasma computer Analysis Network (SPAN), (2) plasmaspheric field-aligned temperature gradients, (3) the shift in spacecraft potential as a function of plasma density, (4) plasma flow, (5) the Fabry-Perot interferometer, and (6) the Differential Ion Flux Probe (DIFP).

Comfort, R. H.; Horwitz, J. L.

1984-01-01

82

Institute for Plasma Science  

E-print Network

Distribution Function in Relativistic Laser- Plasma Interactions Dr. Mark Sherlock, Imperial College London a novel tool for investigating laser- plasma interactions with long and short laser-pulse durations. When Insights into Long and Short-Pulse Laser- Plasma Experiments from Vlasov-Fokker- Planck Simulations Dr

Shyy, Wei

83

Plasma Treatment of Polymers  

Microsoft Academic Search

Plasma treatment of polymers encompasses a variety of plasma technologies and polymeric materials for a wide range of applications and dates back to at least the 1960s. In this article we provide a brief review of the United States patent literature on plasma surface modification technologies and a brief review of the scientific literature on investigations of the effects of

Jeremy M. Grace; Louis J. Gerenser

2003-01-01

84

Report from space plasma science  

NASA Technical Reports Server (NTRS)

Space plasma science, especially plasma experiments in space, is discussed. Computational simulations, wave generation and propagation, wave-particle interactions, charged particle acceleration, particle-particle interactions, radiation transport in dense plasmas, macroscopic plasma flow, plasma-magnetic field interactions, plasma-surface interactions, prospects for near-term plasma science experiments in space and three-dimensional plasma experiments are among the topics discussed.

Hastings, D. E.; Drobot, A.; Banks, Peter M.; Taylor, W. W. L.; Anderson, H. R.

1989-01-01

85

Power Exhaust in Fusion Plasmas  

NASA Astrophysics Data System (ADS)

Preface; 1. Introduction; 2. Magnetized plasma physics; 3. Magnetized plasma equilibrium; 4. Magnetized plasma stability; 5. Collisional transport in magnetized plasmas; 6. Turbulent transport in magnetized plasmas; 7. Tokamak plasma boundary and power exhaust; 8. Outlook: power exhaust in fusion reactors; Appendix A. Maxwellian distribution; Appendix B. Curvilinear co-ordinates; References; Index.

Fundamenski, Wojciech

2014-07-01

86

Plasma and plasma derivatives in therapeutic plasmapheresis.  

PubMed

In therapeutic plasmapheresis, patient plasma is withdrawn and a colloid replacement solution is infused in its place. A 4% to 5% human serum albumin solution in saline is the preferred replacement solution in most instances, even though this practice causes transient mild deficiencies of most plasma proteins. Albumin solutions are pasteurized for viral inactivation, are very unlikely to cause a febrile or allergic reaction, and are convenient to store and administer. Single-donor plasma must be type specific, which requires advance knowledge of patient blood type, and must be ordered and usually thawed before use. It also carries a higher risk of reactions. On the plus side, it replaces all plasma constituents and is appropriate for patients with thrombotic thrombocytopenic purpura or an existing coagulopathy. Neither cryosupernatant plasma, which is relatively deficient in the proteins in cryoprecipitate, nor plasma derived from pools that have been virally inactivated with detergents and organic solvents has been shown to produce better outcomes than fresh frozen plasma for any indication. PMID:22578370

McLeod, Bruce C

2012-05-01

87

Plasma & RF Fundamentals  

NSDL National Science Digital Library

This is a description for a learning module from Maricopa Advanced Technology Education Center. This PDF describes the module; access may be purchased by visiting the MATEC website. One third of modern semiconductor process steps and a variety of other applications employ plasma technology. RF energy is commonly used to generate and maintain a plasma which accelerates chemical processes or provides other desired outcomes such as light emission. This module is the first in a series that builds a knowledge foundation for understanding plasma technology and RF energy. Concepts and principles covered include particle behavior under plasma conditions, changes in electromagnetic wave forms, and related variables that affect RF/plasma applications.

2012-12-27

88

Mirror plasma apparatus  

DOEpatents

A mirror plasma apparatus which utilizes shielding by arc discharge to form a blanket plasma and lithium walls to reduce neutron damage to the wall of the apparatus. An embodiment involves a rotating liquid lithium blanket for a tandem mirror plasma apparatus wherein the first wall of the central mirror cell is made of liquid lithium which is spun with angular velocity great enough to keep the liquid lithium against the first material wall, a blanket plasma preventing the lithium vapor from contaminating the plasma.

Moir, Ralph W. (Livermore, CA)

1981-01-01

89

Plasma -Sheath Interface Problem  

NASA Astrophysics Data System (ADS)

For a collisional bounded plasma problem, it is necessary to model the plasma and sheath separately because of the different scales in each region. We specify the plasma boundary by Godyak's criterion and sheath boundary by Bohm's criterion. We connect the plasma and sheath by a viscous interfacial region where the electric field is approximately constant. The approach enables us to develop and solve universal models for each of the three regions, and combine the solutions continously to approximate the solution to the bounded plasma problem. Comparison of combined solutions with corresponding solution to the bounded plasma problem yields relative error at wall for ion density of 9velocity 10within experimental range. When the interface is neglected and the plasma and sheath are combined, the relative errors are ion density 40Although the interface region is very small it greatly improves the result.

Sternberg, Natalia; Slemrod, Marshall

1999-10-01

90

Plasma contactor research, 1989  

NASA Technical Reports Server (NTRS)

The characteristics of double layers observed by researchers investigating magnetospheric phenomena are contrasted to those observed in plasma contacting experiments. Experiments in the electron collection mode of the plasma contacting process were performed and the results confirm a simple model of this process for current levels ranging to 3 A. Experimental results were also obtained in a study of the process of electron emission from a hollow cathode plasma contactor. High energy ions are observed coming from the cathode in addition to the electrons and a phenomenological model that suggests a mechanism by which this could occur is presented. Experimental results showing the effects of the design parameters of the ambient plasma simulator on the plasma potential, electron temperature, electron density and plasma noise levels induced in plasma contacting experiments are presented. A preferred simulator design is selected on the basis of these results.

Williams, John D.

1990-01-01

91

Plasma contactor research, 1989  

NASA Astrophysics Data System (ADS)

The characteristics of double layers observed by researchers investigating magnetospheric phenomena are contrasted to those observed in plasma contacting experiments. Experiments in the electron collection mode of the plasma contacting process were performed and the results confirm a simple model of this process for current levels ranging to 3 A. Experimental results were also obtained in a study of the process of electron emission from a hollow cathode plasma contactor. High energy ions are observed coming from the cathode in addition to the electrons and a phenomenological model that suggests a mechanism by which this could occur is presented. Experimental results showing the effects of the design parameters of the ambient plasma simulator on the plasma potential, electron temperature, electron density and plasma noise levels induced in plasma contacting experiments are presented. A preferred simulator design is selected on the basis of these results.

Williams, John D.

1990-02-01

92

Plasmas for medicine  

NASA Astrophysics Data System (ADS)

Plasma medicine is an innovative and emerging field combining plasma physics, life science and clinical medicine. In a more general perspective, medical application of physical plasma can be subdivided into two principal approaches. (i) “Indirect” use of plasma-based or plasma-supplemented techniques to treat surfaces, materials or devices to realize specific qualities for subsequent special medical applications, and (ii) application of physical plasma on or in the human (or animal) body to realize therapeutic effects based on direct interaction of plasma with living tissue. The field of plasma applications for the treatment of medical materials or devices is intensively researched and partially well established for several years. However, plasma medicine in the sense of its actual definition as a new field of research focuses on the use of plasma technology in the treatment of living cells, tissues, and organs. Therefore, the aim of the new research field of plasma medicine is the exploitation of a much more differentiated interaction of specific plasma components with specific structural as well as functional elements or functionalities of living cells. This interaction can possibly lead either to stimulation or inhibition of cellular function and be finally used for therapeutic purposes. During recent years a broad spectrum of different plasma sources with various names dedicated for biomedical applications has been reported. So far, research activities were mainly focused on barrier discharges and plasma jets working at atmospheric pressure. Most efforts to realize plasma application directly on or in the human (or animal) body for medical purposes is concentrated on the broad field of dermatology including wound healing, but also includes cancer treatment, endoscopy, or dentistry. Despite the fact that the field of plasma medicine is very young and until now mostly in an empirical stage of development yet, there are first indicators of its enormous economic potential. This ambivalent situation fundamentally requires a responsible use of plasma sources, which are specifically designated for biomedical applications. To enable physicians as well as life scientists to decide whether a given plasma source is really suitable for medical applications or biological experiments, a meaningful and mandatory spectrum of indicators has to be compiled to allow for a basic estimation of the potential of this plasma source.

von Woedtke, Th.; Reuter, S.; Masur, K.; Weltmann, K.-D.

2013-09-01

93

Plasma atomic layer etching using conventional plasma equipment Ankur Agarwala  

E-print Network

Plasma atomic layer etching using conventional plasma equipment Ankur Agarwala Department plasma etching processes having atomic layer resolution. The basis of plasma atomic layer etching PALE will be discussed with the goal of demonstrating the potential of using conventional plasma etching equipment having

Kushner, Mark

94

Plasma abatement of perfluorocompounds in inductively coupled plasma reactors  

E-print Network

Plasma abatement of perfluorocompounds in inductively coupled plasma reactors Xudong ``Peter'' Xu PFCs , gases which have large global warming potentials, are widely used in plasma processing, the effluents from plasma tools using these gases typically have large mole fractions of PFCs. The use of plasma

Kushner, Mark

95

What is a plasma?  

SciTech Connect

This introduction will define the plasma fourth state of matter, where we find plasmas on earth and beyond, and why they are useful. There are applications to many consumer items, fusion energy, scientific devices, satellite communications, semiconductor processing, spacecraft propulsion, and more. Since 99% of our observable universe is ionized gas, plasma physics determines many important features of astrophysics, space physics, and magnetosphere physics in our solar system. We describe some plasma characteristics, examples in nature, some useful applications, how to create plasmas. A brief introduction to the theoretical framework includes the connection between kinetic and fluid descriptions, quasi neutrality, Debye shielding, ambipolar electric fields, some plasma waves. Hands-on demonstrations follow. More complete explanations will follow next week.

Intrator, Thomas P. [Los Alamos National Laboratory

2012-08-30

96

Space plasma physics research  

NASA Technical Reports Server (NTRS)

During the course of this grant, work was performed on a variety of topics and there were a number of significant accomplishments. A summary of these accomplishments is included. The topics studied include empirical model data base, data reduction for archiving, semikinetic modeling of low energy plasma in the inner terrestrial magnetosphere and ionosphere, O(+) outflows, equatorial plasma trough, and plasma wave ray-tracing studies. A list of publications and presentations which have resulted from this research is also included.

Comfort, Richard H.; Horwitz, James L.

1993-01-01

97

Princeton Plasma Physics Laboratory  

SciTech Connect

This report discusses the following topics: principal parameters achieved in experimental devices fiscal year 1990; tokamak fusion test reactor; compact ignition tokamak; Princeton beta experiment- modification; current drive experiment-upgrade; international collaboration; x-ray laser studies; spacecraft glow experiment; plasma processing: deposition and etching of thin films; theoretical studies; tokamak modeling; international thermonuclear experimental reactor; engineering department; project planning and safety office; quality assurance and reliability; technology transfer; administrative operations; PPPL patent invention disclosures for fiscal year 1990; graduate education; plasma physics; graduate education: plasma science and technology; science education program; and Princeton Plasma Physics Laboratory reports fiscal year 1990.

Not Available

1990-01-01

98

Thermalization and plasma instabilities  

E-print Network

I review recent analytical and numerical advances in the study of non-equilibrium quark-gluon plasma physics. I concentrate on studies of the dynamics of plasmas which are locally anisotropic in momentum space. In contrast to locally isotropic plasmas such anisotropic plasmas have a spectrum of soft unstable modes which are characterized by exponential growth of transverse (chromo)-magnetic fields at short times. Parametrically the instabilities provide the fastest method for generation of soft background fields and dominate the short-time dynamics of the system.

Michael Strickland

2006-08-15

99

EDITORIAL: Plasma jets and plasma bullets Plasma jets and plasma bullets  

NASA Astrophysics Data System (ADS)

Plasma plumes, or plasma jets, belong to a large family of gas discharges whereby the discharge plasma is extended beyond the plasma generation region into the surrounding ambience, either by a field (e.g. electromagnetic, convective gas flow, or shock wave) or a gradient of a directionless physical quantity (e.g. particle density, pressure, or temperature). This physical extension of a plasma plume gives rise to a strong interaction with its surrounding environment, and the interaction alters the properties of both the plasma and the environment, often in a nonlinear and dynamic fashion. The plasma is therefore not confined by defined physical walls, thus extending opportunities for material treatment applications as well as bringing in new challenges in science and technology associated with complex open-boundary problems. Some of the most common examples may be found in dense plasmas with very high dissipation of externally supplied energy (e.g. in electrical, optical or thermal forms) and often in or close to thermal equilibrium. For these dense plasmas, their characteristics are determined predominantly by strong physical forces of different fields, such as electrical, magnetic, thermal, shock wave, and their nonlinear interactions [1]. Common to these dense plasma plumes are significant macroscopic plasma movement and considerable decomposition of solid materials (e.g. vaporization). Their applications are numerous and include detection of elemental traces, synthesis of high-temperature materials and welding, laser--plasma interactions, and relativistic jets in particle accelerators and in space [2]-[4]. Scientific challenges in the understanding of plasma jets are exciting and multidisciplinary, involving interweaving transitions of all four states of matter, and their technological applications are wide-ranging and growing rapidly. Using the Web of Science database, a search for journal papers on non-fusion plasma jets reveals that a long initial phase up to 1990 with only 31 papers per year on average, and a total of some 1300 papers, precedes a considerable growth of some 35-50% in research activity every five years, over the last 20 years or so. As shown in the table, the annual dissemination of the field is more than 1600 papers and the total number of papers is in excess of 20000. This upwards trajectory is typical of a strong and growing subject area in physical science, with considerable capacity in both fundamental science and applications. PeriodNumber of papersPapers per annum 1948-1990130031 1991-19952279456 1996-20003447689 2001-20054571914 2006-201066401328 2011 1658 In many of the dense plasma jets discussed above, strong physical forces generated by the plasma are often desired and this favours plasma generation at elevated gas pressure, including atmospheric pressure, which favours a high level of gas ionization. Historically it has been challenging to reduce and control the strong physical forces in high-pressure plasmas for applications where these are unwanted, for example, surface modification of polymeric sheets [5]. Indeed, there is a real need for a vast range of material processing applications at temperatures below 100oC (or below 400 K) and this favours atmospheric-pressure plasma jets sustained far from thermal equilibrium with the dissipated electrical energy largely used not in heat generation but in unleashing non-equilibrium chemical reactions. The long-standing difficulty of effectively controlling the level of gas ionization at atmospheric pressure was overcome by the technological breakthrough of achieving atmospheric-pressure glow discharges in the late 1980s [6]. A related challenge stemming from high collisionality of atmospheric-pressure plasmas (v >> ?0) means that large-area plasmas sustained between parallel-plate electrodes are very susceptible to strong plasma instabilities when molecular gases are introduced for processing applications. This led to an effective technological solution in the early to late 1990s of confining atmospheric plasmas in a small volume

Kong, M. G.; Ganguly, B. N.; Hicks, R. F.

2012-06-01

100

Michigan Institute for Plasma Sci-  

E-print Network

kinetics and plasma elec- trodynamics, plasma diagnostics, light source science and technology, plasmaMichigan Institute for Plasma Sci- ence and Engi- neering Seminar Physics of Low Pressure Inductive Discharges Dr. Valery Godyak RF Plasma Consulting & University of Michigan Wednesday, 1 December 2010 - 4

Shyy, Wei

101

PLASMA PHYSICS PPPL UC Davis  

E-print Network

PRINCETON PLASMA PHYSICS LABORATORY PPPL UC Davis PRINCETON PLASMA PHYSICS LABORATORY PPPL UC Davis. Domier and N.C. Luhmann, Jr. UC at Davis at Workshop on Long Time Simulations of Kinetic Plasmas April 21, 2006 Hyatt Regency, Dallas, TX #12;PRINCETON PLASMA PHYSICS LABORATORY PPPL UC Davis PRINCETON PLASMA

102

Measuring the plasma density of a ferroelectric plasma source in an expanding plasma  

E-print Network

Measuring the plasma density of a ferroelectric plasma source in an expanding plasma A. Dunaevsky and N. J. Fisch Princeton Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New temperature at the surface of a ferroelectric plasma source were deduced from floating probe measurements

103

Partially ionized plasmas, including the Third Symposium on Uranium Plasmas  

NASA Technical Reports Server (NTRS)

Fundamentals of both electrically and fission generated plasmas are discussed. Research in gaseous fuel reactors using uranium hexafluoride is described and other partially ionized plasma applications are discussed.

Krishnan, M.

1976-01-01

104

Introduction to Plasma Physics  

Microsoft Academic Search

There are now many books providing an introduction to plasma physics and any new book must be judged against the competition. This book comes out very well. It deals with basic plasma physics and one of its merits is that the authors, who are both eminent in the field, have resisted the temptation to include more esoteric material. Thus over

J A Wesson

1996-01-01

105

Plasma thrusters from Russia  

SciTech Connect

A report on the Russian stationary plasma thrusters having plasma accelerated to high velocities by electrical and magnetic forces is described. For specific impulses of 15-20 km/sec, optimal for such applications as satellite station keeping and orbital transfer, a unit supplying 0.05 N from a 2-kW input has a 30-cm-diameter nozzle.

Lerner, E.J.

1992-09-01

106

EDITORIAL: Plasma Physics  

Microsoft Academic Search

Plasma physics covers a wide range of phenomena from low-temperature electrons in solids and partially ionised gases in discharges to high-temperature plasma in fusion devices and astrophysics. New theoretical ideas and experimental results have significantly improved our understanding of the, certainly complex, behaviour of this `fourth state of matter'. European Journal of Physics intends to publish a series of articles

A. P. Grecos

2000-01-01

107

Diamagnetism of rotating plasma  

SciTech Connect

Diamagnetism and magnetic measurements of a supersonically rotating plasma in a shaped magnetic field demonstrate confinement of plasma pressure along the magnetic field resulting from centrifugal force. The Grad-Shafranov equation of ideal magnetohydrodynamic force balance, including supersonic rotation, is solved to confirm that the predicted angular velocity is in agreement with spectroscopic measurements of the Doppler shifts.

Young, W. C.; Hassam, A. B.; Romero-Talamas, C. A.; Ellis, R. F.; Teodorescu, C. [IREAP, University of Maryland, College Park, Maryland 20742 (United States)

2011-11-15

108

Madison Plasma Dynamo Experiment  

NASA Astrophysics Data System (ADS)

The Madison Plasma Dynamo Experiment (MPDX) is investigating the self-generation of magnetic fields and related processes in a large, weakly magnetized, fast flowing, and hot (conducting) plasma. The dynamo re-creates conditions highly similar to many astrophysical plasmas. Stars and other planets have dynamos, and so do galaxies and clusters of galaxies, which makes it extremely crucial for researchers in the field to carry out experiments in this previously uninvestigated plasma regime, which will help for the development of a comprehensive theory of how magnetic fields are generated in planets, the Sun and other stars. MPDX is a laboratory astrophysical experiment where 200,000-degree Fahrenheit plasma is confined within a three-meter diameter spherical aluminum vacuum chamber with the help of multiple tracks of cusp magnets covering the inside shell. The dynamo utilizes six robotic insertion sweep probes that are programmed to find any point inside the sphere by given radial and angular coordinates. This innovative mechanical system allows us to take measurements of the state variables in key points in the plasma flow and to better investigate its cosmic-like plasma behavior. The probes are able to autonomously calculate coordinate transformations, move in a two dimensional plane, and return information about their relative position. This makes them an extremely useful, highly accurate, and easily controlled tool for plasma analysis.

Kostadinova, Evdokiya; Forest, C.; Cooper, C.; Coquerel, M.

2014-01-01

109

Plasma-Sprayed Coatings  

Microsoft Academic Search

Plasma spraying is one way to apply protective coatings. The hot, high-speed flame of a plasma gun can melt a powder of almost any ceramic or metal and spray it to form a coating for protection against corrosion, wear or high temperature. The technique carries much less risk of degrading the coating and substrate than many other high-temperature processes do,

Herbert Herman

1988-01-01

110

Criticality in Fusion Plasmas  

E-print Network

: Ohmic mode: it usually takes place while the plasma temperature is low enough to allow Joule heating not make plasma leak too fast out of the magnetic trap. And heat them by any possible mean (i.e., Joule diffusivity along density and temperature gradients magnetic axis last closed surface ECONOMIC FEASIBILITY #12

Martín-Solís, José Ramón

111

Plasma gasification of coals  

SciTech Connect

To avoid problems of transporting coal from Siberia to the European part of the Soviet Union, plasma gasification could be used to give methane and liquid methyl fuel which could be transported by pipeline. Plasma-assisted gasification is particularly effective in the case of brown coals. (11 refs.)

Kruzhilin, G.I.; Khudyakov, G.N.; Tselishchev, P.A.

1981-01-01

112

Triggered plasma opening switch  

SciTech Connect

A triggerable opening switch for a very high voltage and current pulse includes a transmission line extending from a source to a load and having an intermediate switch section including a plasma for conducting electrons between transmission line conductors and a magnetic field for breaking the plasma conduction path and magnetically insulating the electrons when it is desired to open the switch.

Mendel, Clifford W. (Albuquerque, NM)

1988-01-01

113

Triggered plasma opening switch  

SciTech Connect

A triggerable opening switch for a very high voltage and current pulse includes a transmission line extending from a source to a load and having an intermediate switch section including a plasma for conducting electrons between transmission line conductors and a magnetic field for breaking the plasma conduction path and magnetically insulating the electrons when it is desired to open the switch.

Mendel, C.W.

1988-02-23

114

Plasma suppression of beamstrahlung  

SciTech Connect

We investigate the use of a plasma at the interaction point of two colliding beams to suppress beamsstrahlung and related phenomena. We derive conditions for good current cancellation via plasma return currents and report on numerical simulations conducted to confirm our analytic results. 10 refs., 5 figs., 4 tabs.

Whittum, D.H.; Sessler, A.M.; Stewart, J.J.; Yu, S.S.

1988-06-01

115

Plasma engineering for MARS  

SciTech Connect

The two-year Mirror Advanced Reactor Study (MARS) has resulted in the conceptual design of a commercial, electricity-producing fusion reactor based on tandem mirror confinement. The physics basis for the MARS reactor was developed through work in two highly coupled areas of plasma engineering: magnetics and plasma performance.

Carlson, G.A.; Baldwin, D.E.; Barr, W.L.

1983-03-24

116

Heliospheric plasma sheets  

Microsoft Academic Search

As a high-beta feature on scales of hours or less, the heliospheric plasma sheet (HPS) encasing the heliospheric current sheet shows a high degree of variability. A study of 52 sector boundaries identified in electron pitch angle spectrograms in Wind data from 1995 reveals that only half concur with both high-beta plasma and current sheets, as required for an HPS.

N. U. Crooker; C.-L. Huang; S. M. Lamassa; D. E. Larson; S. W. Kahler; H. E. Spence

2004-01-01

117

Plasma treatment of polydimethylsiloxane  

Microsoft Academic Search

Plasma treatment of silicone surfaces is a useful way of increasing wettability to improve adhesion and a first step in producing various organosilicon thin-film composites. Despite numerous earlier studies, there is no consensus on the effect of plasma treatment nor on the mechanism of the subsequent hydrophobic recovery. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to

Michael J. Owen; Patrick J. Smith

1994-01-01

118

Principles of plasma diagnostics.  

NASA Astrophysics Data System (ADS)

This book is a reprint of the 1987 edition (44.003.073). Contents: 1. Plasma diagnostics. 2. Magnetic diagnostics. 3. Plasma particle flux. 4. Refractive-index measurements. 5. Electromagnetic emission by free electrons. 6. Electromagnetic radiation from bound electrons. 7. Scattering of electromagnetic radiation. 8. Ion processes.

Hutchinson, I. H.

119

Plasma technology directory  

SciTech Connect

The Plasma Technology Directory has two main goals: (1) promote, coordinate, and share plasma technology experience and equipment within the Department of Energy; and (2) facilitate technology transfer to the commercial sector where appropriate. Personnel are averaged first by Laboratory and next by technology area. The technology areas are accelerators, cleaning and etching deposition, diagnostics, and modeling.

Ward, P.P.; Dybwad, G.L.

1995-03-01

120

Magnetospheric plasma interactions  

NASA Astrophysics Data System (ADS)

The Earth's magnetosphere (including the ionosphere) is our nearest cosmical plasma system and the only one accessible to mankind for extensive empirical study by in situ measurements. As virtually all matter in the universe is in the plasma state, the magnetosphere provides an invaluable sample of cosmical plasma from which we can learn to better understand the behavior of matter in this state, which is so much more complex than that of unionized matter. It is therefore fortunate that the magnetosphere contains a wide range of different plasma populations, which vary in density over more than six powers of ten and even more in equivalent temperature. Still more important is the fact that its dual interaction with the solar wind above and the atmosphere below make the magnetopshere the site of a large number of plasma phenomena that are of fundamental interest in plasma physics as well as in astrophysics and cosmology. The interaction of the rapidly streaming solar wind plasma with the magnetosphere feeds energy and momentum, as well as matter, into the magnetosphere. Injection from the solar wind is a source of plasma populations in the outer magnetosphere, although much less dominating than previously thought. We now know that the Earth's own atmosphere is the ultimate source of much of the plasma in large regions of the magnetosphere. The input of energy and momentum drives large scale convection of magnetospheric plasma and establishes a magnetospheric electric field and large scale electric current systems that car ry millions of ampere between the ionosphere and outer space. These electric fields and currents play a crucial role in generating one of the the most spectacular among natural phenomena, the aurora, as well as magnetic storms that can disturb man-made systems on ground and in orbit. The remarkable capability of accelerating charged particles, which is so typical of cosmical plasmas, is well represented in the magnetosphere, where mechanisms of such acceleration can be studied in detail. In situ measurements in the magnetosphere have revealed an unexpected tendency of cosmical plasmas to form cellular structure, and shown that the magnetospheric plasma sustains previously unexpected, and still not fully explained, chemical separation mechanisms, which are likely to operate in other cosmical plasmas as well.

Faelthammar, Carl-Gunne

1994-04-01

121

Wakes in inhomogeneous plasmas  

E-print Network

The Debye shielding of a charge immersed in a flowing plasma is an old classic problem in plasma physics. It has been given renewed attention in the last two decades in view of experiments with complex plasmas, where charged dust particles are often levitated in a region with strong ion flow. Efforts to describe the shielding of the dust particles in such conditions have been focused on the homogeneous plasma approximation, which ignores the substantial inhomogeneity of the levitation region. We address the role of the plasma inhomogeneity by rigorously calculating the point charge potential in the collisionless Bohm sheath. We demonstrate that the inhomogeneity can dramatically modify the wake, making it non-oscillatory and weaker.

Kompaneets, Roman; Nosenko, Vladimir; Morfill, Gregor E

2014-01-01

122

Plasma Astrophysics, second edition  

NASA Astrophysics Data System (ADS)

This thoroughly revised textbook is a basic introduction to plasma phenomena in solar and stellar coronae emphasizing non-MHD aspects. The natural way in which the author unifies observations and theory gives a wide perspective to the subject. An important feature is the lucidly written presentation of the fundamentals of plasma physics. The basic theory thus developed is then extended to some exemplary and important observations of coronal dynamics, such as coronal currents, particle acceleration, propagation of particle beams, and shocks. The book has grown from teaching introductory courses on plasma astrophysics at the Swiss Federal Institute of Technology (ETH). It addresses advanced undergraduates and first-year graduate students without a background in plasma physics. It will also be of interest to more senior research workers involved in coronal physics of the Sun and other stars, solar/stellar winds, and various other fields of plasma astrophysics.

Benz, Arnold

2002-06-01

123

Solar system plasma waves  

NASA Technical Reports Server (NTRS)

An overview is given of spacecraft observations of plasma waves in the solar system. In situ measurements of plasma phenomena have now been obtained at all of the planets except Mercury and Pluto, and in the interplanetary medium at heliocentric radial distances ranging from 0.29 to 58 AU. To illustrate the range of phenomena involved, we discuss plasma waves in three regions of physical interest: (1) planetary radiation belts, (2) planetary auroral acceleration regions and (3) the solar wind. In each region we describe examples of plasma waves that are of some importance, either due to the role they play in determining the physical properties of the plasma, or to the unique mechanism involved in their generation.

Gurnett, Donald A.

1995-01-01

124

Plasma opening switch  

DOEpatents

A command triggered plasma opening switch assembly using an amplification stage. The assembly surrounds a coaxial transmission line and has a main plasma opening switch (POS) close to the load and a trigger POS upstream from the main POS. The trigger POS establishes two different current pathways through the assembly depended on whether it has received a trigger current pulse. The initial pathway has both POS's with plasma between their anodes and cathodes to form a short across the transmission line and isolating the load. The final current pathway is formed when the trigger POS receives a trigger current pulse which energizes its fast coil to push the conductive plasma out from between its anode and cathode, allowing the main transmission line current to pass to the fast coil of the main POS, thus pushing its plasma out the way so as to establish a direct current pathway to the load.

Savage, Mark E. (Albuquerque, NM); Mendel, Jr., Clifford W. (Albuquerque, NM)

2001-01-01

125

Plasma physics. Proceedings. 7th Latin American Workshop on Plasma Physics (VII LAWPP 97), Caracas (Venezuela), 20 - 31 Jan 1997  

Microsoft Academic Search

The following topics were dealt with: general plasma theory, plasma confinement, shock waves and instabilities in plasma, plasma spectroscopy, astrophysical and space plasmas, pulse power experiments, plasma processing.

P. Martín; J. Puerta

1997-01-01

126

Neutral Gas Plasma Interactions in Space Plasma  

Microsoft Academic Search

A sounding rocket experiment, CRIT-II, involving the injection of shaped-charge barium in ionospheric plasma was conducted on May 7, 1989, to investigate Alfven's critical ionization velocity (CIV) hypothesis in space. The CRIT -II main payload was instrumented to make in situ measurements within the neutral barium beam. Among the detectors, UNH provided three energetic particle detectors and two photometers. The

Kan Liou

1994-01-01

127

Origins of magnetospheric plasma  

NASA Technical Reports Server (NTRS)

A review is given of recent (1987-1990) progress in understanding of the origins of plasmas in the earth's magnetosphere. In counterpoint to the early supposition that geomagnetic phenomena are produced by energetic plasmas of solar origin, 1987 saw the publication of a provocative argument that accelerated ionospheric plasma could supply all magnetospheric auroral and ring current particles. Significant new developments of existing data sets, as well as the establishment of entirely new data sets, have improved the ability to identify plasma source regions and to track plasma through the magnetospheric system of boundary layers and reservoirs. These developments suggest that the boundary between ionospheric and solar plasmas, once taken to lie at the plasmapause, actually lies much nearer to the magnetopause. Defining this boundary as the surface where solar wind and ionosphere contribute equally to the plasma, it is referred to herein as the 'geopause'. It is now well established that the infusion of ionospheric O(+) plays a major role in the storm-time distention of the magnetotail and inflation of the inner magnetosphere. After more than two decades of observation and debate, the question remains whether magnetosheric are protons of solar or terrestrial origin.

Moore, Thomas E.

1991-01-01

128

Plasma-surface modification of biomaterials  

Microsoft Academic Search

Plasma-surface modification (PSM) is an effective and economical surface treatment technique for many materials and of growing interests in biomedical engineering. This article reviews the various common plasma techniques and experimental methods as applied to biomedical materials research, such as plasma sputtering and etching, plasma implantation, plasma deposition, plasma polymerization, laser plasma deposition, plasma spraying, and so on. The unique

P. K. Chu; J. Y. Chen; L. P. Wang; N. Huang

2002-01-01

129

Plasma Diagnostics and Plasma-Surface Interactions in Inductively Coupled Plasmas.  

E-print Network

??The semiconductor industry's continued trend of manufacturing device features on the nanometer scale requires increased plasma processing control and improved understanding of plasma characteristics and… (more)

Titus, Monica Joy

2010-01-01

130

Ultracold neutral plasmas.  

PubMed

Ultracold neutral plasmas occupy an exotic regime of plasma physics in which electrons form a swarming, neutralizing background for ions that sluggishly move in a correlated manner. Strong interactions between the charged particles give rise to surprising dynamics such as oscillations of the average kinetic energy during equilibration and extremely fast recombination. Such phenomena offer stimulating and challenging problems for computational scientists, and the physics can be applied to other environments, such as the interior of gas giant planets and plasmas created by short-pulse laser irradiation of solid, liquid, and cluster targets. PMID:17478712

Killian, Thomas C

2007-05-01

131

The auroral plasma cavity  

NASA Technical Reports Server (NTRS)

A region of diminished plasma density has been found to occur at the source of auroral kilometric radiation (AKR). The density within this auroral plasma cavity, determined from limited Hawkeye wave data, was less than 1/cu cm from 1.8 to 3 earth radii geocentric, at 70 deg + or - 3 deg invariant magnetic latitude. The altitude variation of the magnetic field produces a minimum in the ratio of plasma frequency to cyclotron frequency within the cavity which accounts for the observed spectrum of AKR.

Calvert, W.

1981-01-01

132

Plasma-aided manufacturing  

NASA Astrophysics Data System (ADS)

The present and potential applications of plasma-aided manufacturing are discussed and described. Plasma-aided manufacturing is used for producing new materials with unusual and superior properties, for developing new chemical compounds and processes, for machining, and for altering and refining materials and surfaces. Plasma-aided manufacturing has direct applications to semiconductor fabrication, materials synthesis, welding, lighting, polymers, anticorrosion coatings, machine tools, metallurgy, electrical and electronics devices, hazardous waste removal, high-performance ceramics, and many other items in both the high-technology and the more traditional industries in the United States.

Shohet, J. L.

1991-10-01

133

Characterization of NRL Capillary Plasma Channels for Laser Plasma Accelerators  

Microsoft Academic Search

Capillary optical guiding experiments at NRL utilize plasma channels formed using both laser ablation and electrical discharge. Present experiments aim to characterize discharge plasma channel and to develop and characterize laser ablation from capillary wall as a formation technique for the guiding plasma. Extended propagation of TW laser pulses has been shown in plasma channels formed with a discharge. Also,

T. G. Jones; C. I. Moore; A. Ting; R. Hubbard; P. Sprangle; D. Kaganovich; K. Krushelnick

2001-01-01

134

CHAPTER 1. COLLECTIVE PLASMA PHENOMENA 1 Collective Plasma  

E-print Network

CHAPTER 1. COLLECTIVE PLASMA PHENOMENA 1 Chapter 1 Collective Plasma Phenomena The properties of a medium are determined by the microscopic processes in it. In a plasma the microscopic processes is actually limited to a distance of order the Debye length in a plasma. On length scales longer than

Callen, James D.

135

The plasma state  

NSDL National Science Digital Library

This segment of a tutorial about plasma--the main state of matter in space--deals with what plasma is and how it is formed. Background information on electric and magnetic fields is also included because plasmas interact with these fields. Enlargeable graphics and an interactive game about the four states of matter complement the segment's four pages of text. In the game, students direct falling objects, such as rocks, lightning, and gasoline, into the appropriate state-of-matter slot. The segment also explains why plasma is so rare on Earth and so abundant in space. A concluding vignette explores Hannes Alfven's ongoing influence on space physics. Alfven was a twentieth-century Nobel laureate. Copyright 2005 Eisenhower National Clearinghouse

Institute, Space S.

2005-01-01

136

Princeton Plasma Physics Laboratory  

NSDL National Science Digital Library

The Princeton Plasma Physics Laboratory: the Fusion Laboratories facilities and mission, including the recent tokamak experiments which resulted in the production of more than 9 million watts of thermonuclear energy.

137

Plasma edge diagnostics  

SciTech Connect

A survey on the needs for plasma edge diagnostics is given followed by a comprehensive overview on optical methods covering emission spectroscopy, laser fluorescence and atomic beams. 11 refs., 13 figs.

Samm, U. [Forschungszentrum Juelich GmbH (Germany)

1996-03-01

138

Reprint from PLASMA PHYSICS  

E-print Network

ATOMIC ENERGY AGENCY VIENNA, 1985 #12;I\\, IAEA-CN-44/E-I1I-9 MAGNETIC ISLANDS IN TOROIDALLY CONFINED OF THE TENTH INTERNATIONAL CONFERENCE ON PLASMA PHYSICS AND CONTROLLED NUCLEAR FUSION RESEARCH HELD BYTHE

Morrison, Philip J.,

139

Magnetospheric Plasma Physics  

NASA Astrophysics Data System (ADS)

Magnetospheric Plasma Physics is volume 4 of an ongoing series of review books entitled Developments in Earth and Planetary Sciences organized by the Center for Academic Publications Japan. The series is intended to stress Japanese work; however, the present volume was written by seven internationally selected authors who have reviewed works from a broad range of sources. This volume is composed of articles drawn from five lecture series presented at the Autumn College o f Plasma Physics, International Center for Theoretical Physics, Trieste, Italy, October-November 1979. The audiences for these lecture series were plasma and/or space plasma physicists, or students of the same, and the level and tone of this volume clearly reflect that condition.

Mauk, Barry H.

140

Triggered plasma opening switch  

SciTech Connect

A triggerable plasma opening switch for connecting a megavolt, megampere power supply to a load is described comprising: cathode means having an input end, an output end, and a switch portion between the ends; anode means having an input end, an output end, and a switch portion between the ends and spaced from the switch portion of the cathode means by a gap; whereby the power supply is connectable between the input ends and the load is connectable between the output ends; plasma source means for filling the gap with a plasma for providing a current path for shorting current from the load; and triggering means for generating a magnetic field for controllably moving the plasma away from one of the anode or the cathode to generate an insulating gap and to block the electron flow across the gap, thereby opening the switch and permitting current to flow from the power supply to the load.

Mendel, C.W.

1988-02-23

141

Saturn's Hot Plasma Explosions  

NASA Video Gallery

This animation based on data obtained by NASA's Cassini Spacecraft shows how the "explosions" of hot plasma on the night side (orange and white) periodically inflate Saturn's magnetic field (white ...

142

Simulation of Fusion Plasmas  

ScienceCinema

The upcoming ITER experiment (www.iter.org) represents the next major milestone in realizing the promise of using nuclear fusion as a commercial energy source, by moving into the ?burning plasma? regime where the dominant heat source is the internal fusion reactions. As part of its support for the ITER mission, the US fusion community is actively developing validated predictive models of the behavior of magnetically confined plasmas. In this talk, I will describe how the plasma community is using the latest high performance computing facilities to develop and refine our models of the nonlinear, multiscale plasma dynamics, and how recent advances in experimental diagnostics are allowing us to directly test and validate these models at an unprecedented level.

Chris Holland

2010-01-08

143

Metal-plasma source  

SciTech Connect

A metal-plasma source is described in which plasma fluxes are generated by semi-self-maintained vacuum discharge in vapors of the working material, which is evaporated from a water-cooled crucible-anode. A cell with crossed magnetic and electric fields is used for additional ionization of the plasma fluxes, which increases the degree of their ionization to 40-65%. The source is especially effective for metallization of dielectric substrates. The use of an additional-ionization cell increased by a factor of 5-8 the adhesion strength of Ni films to polykor substrates. The rate of Ni-film deposition was 0.1-1.0 nm/sec. The plasma source has been used to produce films of Cu, Cr, Ni, Ti, Mo, C, and W with thicknesses of 0.1-2.0 ..mu..m.

Vladimirov, A.I.; Goryuk, S.V.; Saenko, V.A.

1987-10-01

144

Induction plasma tube  

DOEpatents

An induction plasma tube having a segmented, fluid-cooled internal radiation shield is disclosed. The individual segments are thick in cross-section such that the shield occupies a substantial fraction of the internal volume of the plasma enclosure, resulting in improved performance and higher sustainable plasma temperatures. The individual segments of the shield are preferably cooled by means of a counterflow fluid cooling system wherein each segment includes a central bore and a fluid supply tube extending into the bore. The counterflow cooling system results in improved cooling of the individual segments and also permits use of relatively larger shield segments which permit improved electromagnetic coupling between the induction coil and a plasma located inside the shield. Four embodiments of the invention, each having particular advantages, are disclosed.

Hull, Donald E. (Los Alamos, NM)

1984-01-01

145

Induction plasma tube  

DOEpatents

An induction plasma tube having a segmented, fluid-cooled internal radiation shield is disclosed. The individual segments are thick in cross-section such that the shield occupies a substantial fraction of the internal volume of the plasma enclosure, resulting in improved performance and higher sustainable plasma temperatures. The individual segments of the shield are preferably cooled by means of a counterflow fluid cooling system wherein each segment includes a central bore and a fluid supply tube extending into the bore. The counterflow cooling system results in improved cooling of the individual segments and also permits use of relatively larger shield segments which permit improved electromagnetic coupling between the induction coil and a plasma located inside the shield. Four embodiments of the invention, each having particular advantages, are disclosed.

Hull, D.E.

1982-07-02

146

Inductively coupled helium plasma torch  

DOEpatents

An inductively coupled plasma torch including a base member, a plasma tube and a threaded insert member within the plasma tube for directing the plasma gas in a tangential flow pattern. The design of the torch eliminates the need for a separate coolant gas tube. The torch can be readily assembled and disassembled with a high degree of alignment accuracy.

Montaser, Akbar (Potomac, MD); Chan, Shi-Kit (Washington, DC); Van Hoven, Raymond L. (Alexandria, VA)

1989-01-01

147

Michigan Institute for Plasma Science  

E-print Network

Technology. His research interests include thermal plasma processing of materials and plasma spray coatings Michigan Institute for Plasma Science and Engineering Seminar Dynamics of Droplet Impact and Solidification in Plasma Spray Process Prof. Javad Mostaghimi University of Toronto Wednesday, 6 April 2011

Shyy, Wei

148

Atmospheric-pressure plasma technology  

Microsoft Academic Search

Major industrial plasma processes operating close to atmospheric pressure are discussed. Applications of thermal plasmas include electric arc furnaces and plasma torches for generation of powders, for spraying refractory materials, for cutting and welding and for destruction of hazardous waste. Other applications include miniature circuit breakers and electrical discharge machining. Non-equilibrium cold plasmas at atmospheric pressure are obtained in corona

U. Kogelschatz

2004-01-01

149

Supersonic induction plasma jet modeling  

Microsoft Academic Search

Numerical simulations have been applied to study the argon plasma flow downstream of the induction plasma torch. It is shown that by means of the convergent–divergent nozzle adjustment and chamber pressure reduction, a supersonic plasma jet can be obtained. We investigate the supersonic and a more traditional subsonic plasma jets impinging onto a normal substrate. Comparing to the subsonic jet,

S. E. Selezneva; M. I. Boulos

2001-01-01

150

Plasma surface modification of polymers  

NASA Technical Reports Server (NTRS)

Thin plasma polymerization films are discussed from the viewpoint of simplicity in production stages. The application of selective, absorbent films and films used in selective permeability was tested. The types of surface modification of polymers discussed are: (1) plasma etching, (2) surface coating by plasma polymerized thin films, and (3) plasma activation surface graft polymerization.

Hirotsu, T.

1980-01-01

151

Plasma exudation and asthma  

Microsoft Academic Search

Several pieces of evidence support the view that exudation of plasma into the airway wall and into the airway lumen occurs\\u000a in asthma. Vascular leakage of plasma results from inflammatory mediator-induced separation of endothelial cells in postcapillary\\u000a venules belonging to the tracheobronchial circulation. Whereas proposed mediators of asthma induce reversible leakage, several\\u000a antiasthma drugs exhibit antileakage effects in animals and

Carl G. A. Persson

1988-01-01

152

Plasma injection and diamagnetism  

Microsoft Academic Search

A detailed study of the diamagnetic properties of magnetospheric plasma injected at synchronous altitudes is presented. Defining the magnetic induction field B = H + 4piM, the magnetization M is computed from the plasma distribution functions and it is shown that the diamagnetic contribution of the particles having energies of 100 eV to 81 eV can completely account for observed

C. Gurgiolo; C. S. Lin; B. Mauk; G. K. Parks; C. McIlwain

1979-01-01

153

Magnetic reconnection in plasmas  

Microsoft Academic Search

A review of the present status of the theory of magnetic reconnection is given. In strongly collisional plasmas reconnection proceeds via resistive current sheets, i.e. quasi-stationary macroscopic Sweet-Parker sheets at intermediate values of the magnetic Reynolds numberRm, or mirco-current sheets in MHD turbulence, which develops at highRm. In hot, dilute plasmas the reconnection dynamics is dominated by nondissipative effects, mainly

Dieter Biskamp

1996-01-01

154

Carbon plasma gun  

SciTech Connect

A family of plasma guns supplying highly ionized carbon plasma is described. The guns are simple and inexpensive to construct and are pulsed by small capacitor banks of a few hundred joules. The output consists of 10/sup 17/--10/sup 18/ multiply ionized carbon ions traveling at about 10/sup 7/ cm/s. Neutral output is very low and arrives well after the ionized carbon. The guns and pulsers are very reliable.

Mendel, C.W. Jr.; Zagar, D.M.; Mills, G.S.; Humphries, S. Jr.; Goldstein, S.A.

1980-12-01

155

Laser–Plasma Interactions  

Microsoft Academic Search

\\u000a The purpose of the present chapter is to give an introduction into the physics of laser plasma interactions that govern the\\u000a coupling of laser energy into the matter. Processes induced by laser pulses of nano- and femtosecond durations are discussed\\u000a in the framework of different applications. In particular, the roles of non-linear absorption and avalanche ionization in\\u000a plasma heating are

Ion N. Mihailescu; Jörg Hermann

2010-01-01

156

Plasma Screen Floating Mount  

DOEpatents

A mounting system for a flat display screen, particularly a plasma display screen, suspends the screen separately in each of the x-, y- and z-directions. A series of frames located by linear bearings and isolated by springs and dampers allows separate controlled movement in each axis. The system enables the use of relatively larger display screens in vehicles in which plasma screen are subject to damage from vibration.

Eakle, Robert F. (New Ellenton, SC); Pak, Donald J. (Martine, GA)

2004-10-26

157

TOPICAL REVIEW: Plasma-chemical reactions: low pressure acetylene plasmas  

NASA Astrophysics Data System (ADS)

Reactive plasmas are a well-known tool for material synthesis and surface modification. They offer a unique combination of non-equilibrium electron and ion driven plasma chemistry, energetic ions accelerated in the plasma sheath at the plasma-surface interface, high fluxes of reactive species towards surfaces and a friendly environment for thermolabile objects. Additionally, small negatively charged clusters can be generated, because they are confined in the positive plasma potential. Plasmas in hydrocarbon gases, and especially in acetylene, are a good example for the discussion of different plasma-chemical processes. These plasmas are involved in a plethora of possible applications ranging from fuel conversion to formation of single wall carbon nanotubes. This paper provides a concise overview of plasma-chemical reactions (PCRs) in low pressure reactive plasmas and discusses possible experimental and theoretical methods for the investigation of their plasma chemistry. An up-to-date summary of the knowledge about low pressure acetylene plasmas is given and two particular examples are discussed in detail: (a) Ar/C2H2 expanding thermal plasmas with electron temperatures below 0.3 eV and with a plasma chemistry initiated by charge transfer reactions and (b) radio frequency C2H2 plasmas, in which the energetic electrons mainly control PCRs.

Benedikt, J.

2010-02-01

158

Plasma tomography systems for industrial plasma tools  

SciTech Connect

Addressing the geometry constraints that have inhibited the use of optical emission based tomography systems on industrial plasma tools, the University of Michigan has developed a plasma tomography system which uses optical emission spectroscopy (OES) technology and can be operated from a relatively small window compared to the standard Abel geometry previously used by many authors; this change in geometry may make the technique more applicable to industrial plasma tools, which have relatively small windows. The light collection system is based on a rotating point sensor at the surface of the window and reconstructs emissivity from thin wedges of vertically collimated light. This design not only allows for use in small window geometries, but also collects more light than the traditional parallel rays arrangement, thereby providing a better signal to noise ratio for the measurement. This current sensor`s design, results, and a comparison with findings based on Langmuir probe and other OES methods will be presented. Plans for future sensor improvements to allow for multipeak analysis and compatibility with more confining geometries will also be presented.

Shannon, S.C.; Pollack, S.; Holloway, J.P.; Brake, M. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences

1996-12-31

159

Magnetospheric space plasma investigations  

NASA Astrophysics Data System (ADS)

Topics and investigations covering this period of this semiannual report period (August 1994 - January 1995) are as follows: (1) Generalized SemiKinetic (GSK) modeling of the synergistic interaction of transverse heating of ionospheric ions and magnetospheric plasma-driven electric potentials on the auroral plasma transport. Also, presentations of GSK modeling of auroral electron precipitation effects on ionospheric plasma outflows, of ExB effects on such outflow, and on warm plasma thermalization and other effects during refilling with pre-existing warm plasmas; (2) Referees' reports received on the statistical study of the latitudinal distributions of core plasmas along the L = 4.6 field line using DE-1/RIMS data. Other work is concerned in the same field, field-aligned flows and trapped ion distributions; and (3) A short study has been carried out on heating processes in low density flux tubes in the outer plasmasphere. The purpose was to determine whether the high ion temperatures observed in these flux tubes were due to heat sources operating through the thermal electrons or directly to the ions. Other investigations center along the same area of plasmasphere-ionosphere coupling. The empirical techniques and model, the listing of hardware calibrated, and/or tested, and a description of notable meetings attended is included in this report, along with a list of all present publication in submission or accepted and those reference papers that have resulted from this work thus far.

Comfort, Richard H.; Horwitz, James L.

1995-02-01

160

Plasma contactor research - 1991  

NASA Technical Reports Server (NTRS)

A report describing the operating principles of hollow-cathode-based plasma contactors emitting or collecting electrons from an ambient plasma is summarized. Preliminary experiments conducted to determine the noise generated by these plasma contactors in the emission-current return line and in the plasma near it are described. These noise data are measured as current fluctuations in the return line and to the Langmuir probe and then analyzed using a fast Fourier transform technique. The spectral compositions of the data are characterized using power spectral density plots which are examined to identify possible noise source(s) and production mechanism(s). The precautions taken in the construction and calibration of the instrumentation to assure adequate frequency response are described. Experimental results show that line-current noise levels are typically 2 percent of the electron current being emitted or collected. However, noise levels increase to as much as 20 percent of the electron current at a few electron-collection operating conditions. The frequencies associated with most of the noise were harmonics of the 60 Hz input to system power supplies. Plasma noise had characteristics similar in magnitude and frequency to those for the return-line noise, but they contained additional features at frequencies considered to be related to ion-acoustic instabilities. Also discussed is a new probe positioning system built to facilitate future plasma-contractor research.

Buchholtz, Brett; Williams, John D.; Wilbur, Paul J.

1992-01-01

161

Magnetospheric space plasma investigations  

NASA Technical Reports Server (NTRS)

Topics and investigations covering this period of this semiannual report period (August 1994 - January 1995) are as follows: (1) Generalized SemiKinetic (GSK) modeling of the synergistic interaction of transverse heating of ionospheric ions and magnetospheric plasma-driven electric potentials on the auroral plasma transport. Also, presentations of GSK modeling of auroral electron precipitation effects on ionospheric plasma outflows, of ExB effects on such outflow, and on warm plasma thermalization and other effects during refilling with pre-existing warm plasmas; (2) Referees' reports received on the statistical study of the latitudinal distributions of core plasmas along the L = 4.6 field line using DE-1/RIMS data. Other work is concerned in the same field, field-aligned flows and trapped ion distributions; and (3) A short study has been carried out on heating processes in low density flux tubes in the outer plasmasphere. The purpose was to determine whether the high ion temperatures observed in these flux tubes were due to heat sources operating through the thermal electrons or directly to the ions. Other investigations center along the same area of plasmasphere-ionosphere coupling. The empirical techniques and model, the listing of hardware calibrated, and/or tested, and a description of notable meetings attended is included in this report, along with a list of all present publication in submission or accepted and those reference papers that have resulted from this work thus far.

Comfort, Richard H.; Horwitz, James L.

1995-01-01

162

Plasma scattering of electromagnetic radiation  

Microsoft Academic Search

The scattered power spectrum is considered along with aspects of incoherent scattering, constraints on scattering experiments, optical systems, the theory concerning the scattered spectrum for a low-temperature plasma, and questions of scattering from a low-temperature stable plasma. Attention is also given to scattering from a magnetized plasma, scattering from a high-temperature plasma, scattering from unstable plasmas, the kinetic theory of

J. Sheffield

1975-01-01

163

Plasma diagnostics and plasma-surface interactions in inductively coupled plasmas  

Microsoft Academic Search

The semiconductor industry's continued trend of manufacturing device features on the nanometer scale requires increased plasma processing control and improved understanding of plasma characteristics and plasma-surface interactions. This dissertation presents a series of experimental results for focus studies conducted in an inductively coupled plasma (ICP) system. First novel \\

Monica Joy Titus

2010-01-01

164

Understanding helicon plasmas  

SciTech Connect

This paper presents a comprehensive overview of work on the helicon plasmas and also discusses various aspects of RF power deposition in such plasmas. Some of the work presented here is a review of earlier work on theoretical [A. Ganguli et al., Phys. Plasmas 14, 113503 (2007)] and experimental [A. Ganguli et al., Plasma Sources Sci. Technol. 20(1), 015021 (2011)] investigations on helicon plasmas in a conducting cylindrical waveguide for m = -1 mode. This work also presents an approach to investigate the mechanisms by which the helicon and associated Trivelpiece-Gould (TG) waves are responsible for RF power deposition in Helicon discharges. Experiment design adopts the recent theory of damping and absorption of Helicon modes in conducting waveguides [A. Ganguli et al., Phys. Plasmas 14, 113503 (2007)]. The effort has also been made to detect the warm electrons, which are necessary for ionization, because Helicon discharges are of high density, low T{sub e} discharges and the tail of the bulk electron population may not have sufficient high-energy electrons. Experimental set up also comprises of the mirror magnetic field. Measurements using RF compensated Langmuir probes [A. Ganguli et al., Plasma Sources Sci. Technol. 17, 015003 (2008)], B-dot probe and computations based on the theory shows that the warm electrons at low pressure (0.2-0.3 mTorr) Helicon discharges, are because of the Landau damping of TG waves. In collisional environment, at a pressure Almost-Equal-To 10 mTorr, these high-energy electrons are due to the acceleration of bulk electrons from the neighboring regions across steep potential gradients possibly by the formation of double layers.

Tarey, R. D. [Department of Physics, Indian Institute of Technology, New Delhi 110016 (India); Sahu, B. B. [Department of Applied Sciences and Humanities, Dronacharya College of Engineering, Gurgaon 123506 (India); Ganguli, A. [Centre for Energy Studies, Indian Institute of Technology, New Delhi 110016 (India)

2012-07-15

165

Plasma wakefield acceleration in self-ionized gas or plasmas.  

PubMed

Tunnel ionizing neutral gas with the self-field of a charged particle beam is explored as a possible way of creating plasma sources for a plasma wakefield accelerator [Bruhwiler et al., Phys. Plasmas (to be published)]. The optimal gas density for maximizing the plasma wakefield without preionized plasma is studied using the PIC simulation code OSIRIS [R. Hemker et al., in Proceeding of the Fifth IEEE Particle Accelerator Conference (IEEE, 1999), pp. 3672-3674]. To obtain wakefields comparable to the optimal preionized case, the gas density needs to be seven times higher than the plasma density in a typical preionized case. A physical explanation is given. PMID:14683089

Deng, S; Barnes, C D; Clayton, C E; O'Connell, C; Decker, F J; Erdem, O; Fonseca, R A; Huang, C; Hogan, M J; Iverson, R; Johnson, D K; Joshi, C; Katsouleas, T; Krejcik, P; Lu, W; Marsh, K A; Mori, W B; Muggli, P; Tsung, F

2003-10-01

166

Plasma plume propagation characteristics of pulsed radio frequency plasma jet  

SciTech Connect

A 4 cm long helium cold atmospheric pressure plasma jet with pulsed radio frequency (rf) excitation was obtained by a copper electrode inside a quartz tube. The plasma bullet propagation characteristics common to the microseconds direct current pulse and kilohertz plasma jet is not observed in this case. The space-, time-, and wavelength-resolved optical emission profiles suggest the pulsed rf plasma channel out of the tube was strengthened by ions and metastables with longer life time than the rf period, and the plasma propagation was actually an illumination of the plasma channel caused by energetic electrons accelerated along the channel.

Liu, J. H.; Liu, X. Y.; Hu, K.; Liu, D. W.; Lu, X. P. [Advanced Electromagnetic Engineering and Technology Laboratory, Huazhong University of Science and Technology, WuHan, HuBei 430074 (China); Iza, F.; Kong, M. G. [Department of Electronic and Electrical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

2011-04-11

167

Plasma coal reprocessing  

NASA Astrophysics Data System (ADS)

Results of many years of investigations of plasma-chemical technologies for pyrolysis, hydrogenation, thermochemical preparation for combustion, gasification, and complex reprocessing of solid fuels and hydrocarbon gas cracking are represented. Application of these technologies for obtaining the desired products (hydrogen, industrial carbon, synthesis gas, valuable components of the mineral mass of coal) corresponds to modern ecological and economical requirements to the power engineering, metallurgy, and chemical industry. Plasma fuel utilization technologies are characterized by the short-term residence of reagents within a reactor and the high degree of the conversion of source substances into the desired products without catalyst application. The thermochemical preparation of the fuel to combustion is realized in a plasma-fuel system presenting a reaction chamber with a plasmatron; and the remaining plasma fuel utilization technologies, in a combined plasma-chemical reactor with a nominal power of 100 kW, whose zone of the heat release from an electric arc is joined with the chemical reaction zone.

Messerle, V. E.; Ustimenko, A. B.

2013-12-01

168

MACROPHAGE PLASMA MEMBRANES  

PubMed Central

Plasma membranes have been isolated from pure populations of rabbit alveolar macrophages which were swollen in water, fixed briefly with glutaraldehyde, disrupted by Dounce homogenization, and separated by sucrose gradient centrifugation. The recovered membranes exhibited good structural preservation and enzymatic activity; both morphologic and biochemical evidence indicated a high degree of purity (>90%) of the membrane preparation. Interiorized plasma membranes were also prepared without exposure to glutaraldehyde from phagocytic vacuoles recovered from alveolar macrophages which had ingested large numbers of polystyrene spheres. These membranes were contaminated with lysosomal constituents, but they were nevertheless of value for comparison to the "pure" membranes isolated by the glutaraldehyde procedure. Acrylamide gel electrophoresis of the solubilized plasma membranes and phagolysosomal membranes revealed similar protein patterns, with seven to nine individual components ranging in molecular weight from 70,000 to 140,000. The two most rapidly migrating components gave positive reactions for lipid as well as protein. A band containing carbohydrate was detected near the origin of the plasma membrane gels. Antisera were made by injecting guinea pigs with the purified rabbit alveolar macrophage plasma membranes. Gel diffusion and immunoelectrophoretic study of these antisera established the presence of rabbit immunoglobulin G and of one or two other antigenic constituents in the membrane preparation. PMID:4323071

Nachman, Ralph L.; Ferris, Barbara; Hirsch, James G.

1971-01-01

169

Pulsed Plasma Accelerator Modeling  

NASA Technical Reports Server (NTRS)

This report presents the main results of the modeling task of the PPA project. The objective of this task is to make major progress towards developing a new computational tool with new capabilities for simulating cylindrically symmetric 2.5 dimensional (2.5 D) PPA's. This tool may be used for designing, optimizing, and understanding the operation of PPA s and other pulsed power devices. The foundation for this task is the 2-D, cylindrically symmetric, magnetohydrodynamic (MHD) code PCAPPS (Princeton Code for Advanced Plasma Propulsion Simulation). PCAPPS was originally developed by Sankaran (2001, 2005) to model Lithium Lorentz Force Accelerators (LLFA's), which are electrode based devices, and are typically operated in continuous magnetic field to the model, and implementing a first principles, self-consistent algorithm to couple the plasma and power circuit that drives the plasma dynamics.

Goodman, M.; Kazeminezhad, F.; Owens, T.

2009-01-01

170

Processes in relativistic plasmas  

NASA Technical Reports Server (NTRS)

The establishment and maintenance of a Boltzmann distribution in particle kinetic energies is investigated for a plasma with theta = KTe/mc-squared much greater than unity, where m is the electron mass. It is shown that thermalization of the electron gas by binary collisions is not sufficiently effective to maintain the equilibrium distribution when other processes that perturb the equilibrium are taken into account. Electron-positron pair production in electron-electron and electron-ion collisions, and perturbations of a Boltzmann distribution by nonthermal processes are evaluated. Thermalization by means of other mechanisms, such as interaction with plasma waves is discussed, and the opacity of a relativistic plasma is computed for Compton scattering, pair production in the fields of electrons and ions, inverse bremsstrahlung, and synchrotron self-absorption.

Gould, R. J.

1982-01-01

171

Processes in relativistic plasmas  

NASA Astrophysics Data System (ADS)

The establishment and maintenance of a Boltzmann distribution in particle kinetic energies is investigated for a plasma with theta = KTe/mc-squared much greater than unity, where m is the electron mass. It is shown that thermalization of the electron gas by binary collisions is not sufficiently effective to maintain the equilibrium distribution when other processes that perturb the equilibrium are taken into account. Electron-positron pair production in electron-electron and electron-ion collisions, and perturbations of a Boltzmann distribution by nonthermal processes are evaluated. Thermalization by means of other mechanisms, such as interaction with plasma waves is discussed, and the opacity of a relativistic plasma is computed for Compton scattering, pair production in the fields of electrons and ions, inverse bremsstrahlung, and synchrotron self-absorption.

Gould, R. J.

1982-03-01

172

Plasma Equilibrium in Tokamaks  

SciTech Connect

The task of the theory of tokamak equilibrium is to determine the global magnetic confinement topology and physical characteristics of the underlying basic equilibrium state, which is assumed to be static (both [partial derivative]/[partial derivative]t = 0 and background velocity v{sub 0} = 0). This could be considered to be the most boring case of plasma behavior, viz. total absence of dynamics: a corresponding fluid dynamics problem hardly exists. The reason for our interest in this plasma state is the prospect of obtaining clean, abundant, and cheap energy from controlled thermonuclear fusion reactions. Of course, criticism and doubt immediately enter the mind after a statement like this. Nevertheless, let us study this plasma state, leaving questions like 'is there such a state at all?' and 'is it actually so desirable?' for later (Sec. 5)

Goedbloed, J.P. [FOM- Institute for Plasma Physics 'Rijnhuizen' (Netherlands)

2004-03-15

173

Glossary of Plasma Physics  

NSDL National Science Digital Library

From the Princeton Plasma Physics Laboratory's FusEdWeb: Fusion Energy Educational Web Site, this glossary of plasma physics "seeks to provide plain-language definitions of over 3600 frequently used technical terms in Plasma Physics (all areas) and Fusion Energy Research." The glossary is intended to help facilitate discussion "between experts and non-experts, and even between experts in different subfields." Users may search, submit new terms for review by editors, or browse alphabetically for terms in fields including scientific vocabulary, names of research facilities, experimental machines and devices used, names of researchers, key mathematical symbols, and acronyms. Over a thousand of these terms are fully defined on-site, and references are provided for looking up most of the remaining terms.

2007-05-04

174

Glossary of Plasma Physics  

NSDL National Science Digital Library

From the Princeton Plasma Physics Laboratory's FusEdWeb: Fusion Energy Educational Web Site, this glossary of plasma physics "seeks to provide plain-language definitions of over 3600 frequently used technical terms in Plasma Physics (all areas) and Fusion Energy Research." The glossary is intended to help facilitate discussion "between experts and non-experts, and even between experts in different subfields." Users may search, submit new terms for review by editors, or browse alphabetically for terms in fields including scientific vocabulary, names of research facilities, experimental machines and devices used, names of researchers, key mathematical symbols, and acronyms. Over a thousand of these terms are fully defined on-site, and references are provided for looking up most of the remaining terms.

175

Perturbations in a plasma  

E-print Network

The perturbations of a homogeneous non-relativistic two-component plasma are studied in the Coulomb gauge. Starting from the solution found [2] of the equations of electromagnetic self consistency in a plasma [1], we add small perturbations to all quantities involved, and we enter the perturbed quantities in the equations, keeping only the first order terms in the perturbations. Because the unperturbed quantities are solutions of the equations, they cancel each other, and we are left with a set of 12 linear equations for the 12 perturbations (unknown quantities). Then we solve this set of linearized equations, in the approximation of small ratio of the masses of electrons over those of ions, and under the assumption that the plasma remains homogeneous.

Evangelos Chaliasos

2005-10-20

176

Plasma effects on subcellular structures  

SciTech Connect

Atmospheric pressure helium plasma treated human hepatocytes exhibit distinctive zones of necrotic and live cells separated by a void. We propose that plasma induced necrosis is attributed to plasma species such as oxygen radicals, charged particles, metastables and/or severe disruption of charged cytoskeletal proteins. Interestingly, uncharged cytoskeletal intermediate filaments are only minimally disturbed by plasma, elucidating the possibility of plasma induced electrostatic effects selectively destroying charged proteins. These bona fide plasma effects, which inflict alterations in specific subcellular structures leading to necrosis and cellular detachment, were not observed by application of helium flow or electric field alone.

Gweon, Bomi; Kim, Dan Bee; Jung, Heesoo; Choe, Wonho [Department of Physics, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Kim, Daeyeon [Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Shin, Jennifer H. [Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

2010-03-08

177

Plasma effects on subcellular structures  

NASA Astrophysics Data System (ADS)

Atmospheric pressure helium plasma treated human hepatocytes exhibit distinctive zones of necrotic and live cells separated by a void. We propose that plasma induced necrosis is attributed to plasma species such as oxygen radicals, charged particles, metastables and/or severe disruption of charged cytoskeletal proteins. Interestingly, uncharged cytoskeletal intermediate filaments are only minimally disturbed by plasma, elucidating the possibility of plasma induced electrostatic effects selectively destroying charged proteins. These bona fide plasma effects, which inflict alterations in specific subcellular structures leading to necrosis and cellular detachment, were not observed by application of helium flow or electric field alone.

Gweon, Bomi; Kim, Daeyeon; Kim, Dan Bee; Jung, Heesoo; Choe, Wonho; Shin, Jennifer H.

2010-03-01

178

Partial pressure analysis of plasmas  

SciTech Connect

The application of partial pressure analysis for plasma diagnostic measurements is reviewed. A comparison is made between the techniques of plasma flux analysis and partial pressure analysis for mass spectrometry of plasmas. Emphasis is given to the application of quadrupole mass spectrometers (QMS). The interface problems associated with the coupling of a QMS to a plasma device are discussed including: differential-pumping requirements, electromagnetic interferences from the plasma environment, the detection of surface-active species, ion source interactions, and calibration procedures. Example measurements are presented from process monitoring of glow discharge plasmas which are useful for cleaning and conditioning vacuum vessels.

Dylla, H.F.

1984-11-01

179

Laser spectroscopy of thermal plasma  

NASA Astrophysics Data System (ADS)

Thermal plasma, due to its applications, is a research field of great importance, but reliable diagnostics of such plasma remains a challenging task. Spatially resolved methods, which provide local values of plasma parameters, are crucial for understanding the underlying physics. This can be achieved using pump-probe techniques. Two methods applicable and useful for thermal plasma diagnostics—four-wave mixing and scattering of laser beams—are discussed in this paper. Experimental examples of their application, namely four-wave mixing in argon arc plasma and scattering of laser light by laser-induced plasma, are presented.

Pokrzywka, Bart?omiej; Dzier??ga, Krzysztof; Mendys, Agata; Pellerin, Stephane

2014-05-01

180

Plasma Simulation Program  

SciTech Connect

Many others in the fusion energy and advanced scientific computing communities participated in the development of this plan. The core planning team is grateful for their important contributions. This summary is meant as a quick overview the Fusion Simulation Program's (FSP's) purpose and intentions. There are several additional documents referenced within this one and all are supplemental or flow down from this Program Plan. The overall science goal of the DOE Office of Fusion Energy Sciences (FES) Fusion Simulation Program (FSP) is to develop predictive simulation capability for magnetically confined fusion plasmas at an unprecedented level of integration and fidelity. This will directly support and enable effective U.S. participation in International Thermonuclear Experimental Reactor (ITER) research and the overall mission of delivering practical fusion energy. The FSP will address a rich set of scientific issues together with experimental programs, producing validated integrated physics results. This is very well aligned with the mission of the ITER Organization to coordinate with its members the integrated modeling and control of fusion plasmas, including benchmarking and validation activities. [1]. Initial FSP research will focus on two critical Integrated Science Application (ISA) areas: ISA1, the plasma edge; and ISA2, whole device modeling (WDM) including disruption avoidance. The first of these problems involves the narrow plasma boundary layer and its complex interactions with the plasma core and the surrounding material wall. The second requires development of a computationally tractable, but comprehensive model that describes all equilibrium and dynamic processes at a sufficient level of detail to provide useful prediction of the temporal evolution of fusion plasma experiments. The initial driver for the whole device model will be prediction and avoidance of discharge-terminating disruptions, especially at high performance, which are a critical impediment to successful operation of machines like ITER. If disruptions prove unable to be avoided, their associated dynamics and effects will be addressed in the next phase of the FSP.

Greenwald, Martin

2011-10-04

181

Plasma contactor research, 1990  

NASA Technical Reports Server (NTRS)

Emissive and Langmuir probes were used to measure plasma potential profiles, plasma densities, electron energy distributions, and plasma noise levels near a hollow cathode-based plasma contactor emitting electrons. The effects of electron emission current (100 to 1500 mA) and contactor flowrate (2 to 10 sccm (Xenon)) on these data are examined. Retarding potential analyzer (RPA) measurements showing that high energy ions generally stream from a contactor along with the electrons being emitted are also presented, and a mechanism by which this occurs is postulated. This mechanism, which involves a high rate of ionization induced between electrons and atoms flowing together from the hollow cathode orifice, results in a region of high positive space charge and high positive potential. Langmuir and RPA probe data suggests that both electrons and ions expand spherically from this potential hill region. In addition to experimental observations, a simple one-dimensional model which describes the electron emission process and predicts the phenomena just mentioned is presented and is shown to agree qualitatively with these observations. Experimental results of the first stage of bilateral cooperation with the Italian Institute of Interplanetary Space Physics (IFSI CNR) are presented. Sharp, well-defined double layers were observed downstream of a contactor collecting electrons from an ambient plasma created in the IFSI Facility. The voltage drop across these double layers was observed to increase with the current drawn from the ambient plasma. This observation, which was not as clear in previous IFSI tests conducted at higher neutral pressures, is in agreement with previous experimental observations made at both Colorado State University and NASA Lewis Research Center. Greater double layer voltage drops, multiple double layers, and higher noise levels in the region near the double layers were also observed when a magnetic field was imposed and oriented perpendicular to the line joining the contactor and simulator.

Williams, John D.; Wilbur, Paul J.

1991-01-01

182

Design of a Plasma Injector for a Pulsed Plasma Accelerator  

NASA Technical Reports Server (NTRS)

In recent years, a pulsed plasma accelerator has been proposed as a candidate stand-off driver for the formation of an imploding liner in magnetized target fusion. For a near-term physics exploratory experiment to study the feasibility of this standoff approach, a plasma accelerator has been proposed that requires the controlled introduction and preparation of the initial plasma for acceleration. This includes uniform injection of the propellant downstream of the breech with a high degree of ionization. The design of a plasma feed is presented, which injects a high conductivity, highly collisional propellant transverse to the conductor. The plasma injector is designed to establish an initial plasma with a moderate Hall parameter at the trailing edge of the plasma slug, high Hall parameter behind the slug for magnetic insulation, and a short diffusion length in comparison with characteristic dimensions of the plasma slug to avoid propellant loss at the trailing edge.

Cassibry, J. T.; Thio, Y. C. F.; Markusic, T. E.; Sommers, J.; Rodgers, Stephen L. (Technical Monitor)

2002-01-01

183

Quark-Gluon Plasma Thermalization and Plasma Instabilities  

E-print Network

In this talk, I review the important role played by plasma instabilities in the thermalization of quark-gluon plasmas at very high energy. [Conference talk presented at Strong and Electroweak Mattter 2004, Helsinki, Finland, June 16--19.

Peter Arnold

2004-08-31

184

Solar flares. [plasma physics  

NASA Technical Reports Server (NTRS)

The present paper deals with explosions in a magnetized solar plasma, known as flares, whose effects are seen throughout the electromagnetic spectrum, from gamma-rays through the visible and to the radio band. The diverse phenomena associated with flares are discussed, along with the physical mechanisms that have been advanced to explain them. The impact of solar flare research on the development of plasma physics and magnetohydrodynamics is noted. The rapid development of solar flare research during the past 20 years, owing to the availability of high-resolution images, detailed magnetic field measurements, and improved spectral data, is illustrated.

Rust, D. M.

1979-01-01

185

Plasma Spray System  

NASA Technical Reports Server (NTRS)

Computer aided, fully-automatic TRW system sprays very hot plasma onto a turbine blade. Composed of gas into which metallic and ceramic powders have been injected, the plasma forms a two-layer coating which insulates the blade. Critical part of operation is controlling the thickness of the deposit which is measured in thousandths of an inch. This is accomplished by an optical detector which illuminates spots at various locations on the blade and determines thickness by measuring the light reflections. Optical sensor monitors spraying process until precise thickness is attained, then computer halts the spraying.

1980-01-01

186

Undamped plasma waves  

NASA Technical Reports Server (NTRS)

This paper describes small-amplitude nonlinear plasma wave solutions to the one-dimensional Vlasov-Maxwell equations. A sufficient condition for waves of a given phase velocity to exist arbitrarily close to a given spatially uniform Vlasov equilibrium is developed, and sufficient analytical information for the construction of approximate expressions for the electric potential and distribution functions is derived, with exact knowledge of the asymptotic behavior of the error terms. These results have a very surprising physical implication: the Landau damping of small-amplitude waves is not inevitable. Instead, there exist plasma waves that trap particles even at arbitrarily small amplitude and do not damp.

Holloway, James P.; Dorning, J. J.

1991-01-01

187

A contoured gap coaxial plasma gun with injected plasma armature  

Microsoft Academic Search

A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 mug of plasma with density above 1017 cm-3 to greater than 200 km\\/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined

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

2009-01-01

188

Plasma Facing Component Science and Technology for Burning Plasma Experiments  

E-print Network

Reactor Radiant Flux at Sun Surface Rocket Nozzles Comparison Relative Heat Fluxes Fusion Plasma #12;MAU contract DE-AC04-94AL85000. #12;MAU 12/8/00 2 · Burning plasma device designs · Pulse length issues issues · Materials Science issues · Conclusions Outline #12;MAU 12/8/00 3 Burning Plasma Device Designs

189

A low energy plasma flood gun using RF plasma formation  

Microsoft Academic Search

A plasma flood gun (PFG) system useful for 300 mm wafer has been developed by using an RF plasma for the medium current implanter EXCEED2300. To produce low energy electrons, the electron energy is filtered by magnetic fields. To eliminate dose shift, a low flow rate of Xe gas is adopted. A linear geometry of the plasma production source chamber

S. Sakai; N. Hamamoto; T. Ikejiri; M. Tanjyo

2000-01-01

190

Mobile plasma activation of polymers using the plasma gun  

Microsoft Academic Search

Surface activation of hydrophobic polymers is important prior to effective painting and glueing. The purpose of the plasma gun is the activation of polymers under normal pressure using a plasma excitation. Its function principle is based on a gas jet pump. Under low pressure a plasma is burning induced by an electrical discharge. The activation process takes place under ambient

Roland Gesche; Reinhold Kovacs; Joachim Scherer

2005-01-01

191

Laser-plasma interactions in ignition-scale hohlraum plasmas  

Microsoft Academic Search

Scattering of laser light by stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) is a concern for indirect drive inertial confinement fusion (ICF). The hohlraum designs for the National Ignition Facility (NIF) raise particular concerns due to the large scale and homogeneity of the plasmas within them. Experiments at Nova have studied laser–plasma interactions within large scale length plasmas

B. J. MacGowan; B. B. Afeyan; C. A. Back; R. L. Berger; G. Bonnaud; M. Casanova; B. I. Cohen; D. E. Desenne; D. F. Dubois; A. G. Dulieu; K. G. Estabrook; J. C. Fernandez; S. H. Glenzer; D. E. Hinkel; T. B. Kaiser; R. L. Kauffman; R. K. Kirkwood; W. L. Kruer; A. B. Langdon; B. F. Lasinski; D. S. Montgomery; J. D. Moody; D. H. Munro; L. V. Powers; H. A. Rose; C. Rousseaux; R. E. Turner; B. H. Wilde; S. C. Wilks; E. A. Williams

1996-01-01

192

Plasma treatments and plasma deposition of polymers for biomedical applications  

Microsoft Academic Search

The aim of this review is to describe how biomaterial engineering processes, particularly in the field of polymer modifications for enhanced blood-compatibility, can take advantage of low-pressure plasma techniques. It will also be emphasized how a diagnostic approach on both plasma and surface reactions can lead to understand and control the chemistry of plasma processes.

Pietro Favia; Riccardo d’Agostino

1998-01-01

193

Recent results for plasma antennas  

SciTech Connect

Plasma antennas are just as effective as metal antennas. They can transmit, receive, and reflect radio waves just as well as metal antennas. In addition, plasma generated noise does not appear to be a problem.

Alexeff, Igor; Anderson, Ted; Farshi, Esmaeil; Karnam, Naresh; Pulasani, Nanditha Reddy [Department of Electrical Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States)

2008-05-15

194

A microwave plasma cleaning apparatus  

NASA Technical Reports Server (NTRS)

In a microwave electron cyclotron resonance plasma source, reactive plasmas of oxygen and its mixtures of argon have been used for evaluating plasma cleaning technologies. Small aluminum samples (0.95 x 1.9 cm) were coated with thin films (less than or equal to 20 micrometers in thickness) of Shell Vitrea oil and cleaned with reactive plasmas. The discharge parameters, such as gas pressure, magnetic field, substrate biasing, and microwave power, were varied to change cleaning conditions. A mass spectroscopy (or residual gas analyzer) was used to monitor the status of plasma cleaning. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured cleaning rates of low-pressure (0.5-m torr) argon/oxygen plasmas were as high as 2.7 micrometers/min. X-ray photoelectron spectroscopy was used to determine cleanliness of the sample surfaces. In this paper, significant results of the plasma cleaning are reported and discussed.

Tsai, C. C.; Nelson, W. D.; Schechter, D. E.; Thompson, L. M.; Glover, A. L.

1995-01-01

195

A microwave plasma cleaning apparatus  

SciTech Connect

In a microwave electron cyclotron resonance plasma source, reactive plasmas of oxygen and its mixtures of argon have been used for evaluating plasma cleaning technologies. Small aluminum samples (0.95 x 1.9 cm) were coated with thin films ({le} 20 {micro}m in thickness) of Shell Vitrea oil and cleaned with reactive plasmas. The discharge parameters, such as gas pressure, magnetic field, substrate biasing, and microwave power, were varied to change cleaning conditions. A mass spectroscopy (or residual gas analyzer) was used to monitor the status of plasma cleaning. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured cleaning rates of low-pressure (0.5-mtorr) argon/oxygen plasmas were as high as 2.7 {micro}m/min. X-ray photoelectron spectroscopy was used to determine cleanliness of the sample surfaces. In this paper, significant results of the plasma cleaning are reported and discussed.

Tsai, C.C.; Nelson, W.D.; Schechter, D.E. [Oak Ridge National Lab., TN (United States); Thompson, L.M.; Glover, A.L. [Oak Ridge Y-12 Plant, TN (United States)

1994-12-31

196

Process Sprays Uniforms Plasma Coatings  

NASA Technical Reports Server (NTRS)

Composite-powder processing procedure developed along with plasma-spray parameters to achieve homogeneous, well-bonded, low-porosity, self-lubricating coatings. Multicomponent plasma coatings are applied without segretation of components.

Sliney, H. E.; Jacobson, T. P.; Walther, G. C.; Nakamura, H. H.

1983-01-01

197

Plasma contactors for electrodynamic tether  

NASA Technical Reports Server (NTRS)

The role plasma contactors play in effective electrodynamic tether operation is discussed. Hollow cathodes and hollow cathode-based plasma sources have been identified as leading candidates for the electrodynamic tether plasma contactor. Present experimental efforts to evaluate the suitability of these devices as plasma contactors, conducted concurrently at NASA Lewis Research Center and Colorado State University, are reviewed. These research programs include the definition of preliminary plasma contactor designs, and the characterization of their operation both as electron emitters and electron collectors to and from a simulated space plasma. Results indicate that ampere-level electron currents, sufficient for electrodynamic tether operation, can be exchanged between hollow cathode-based plasma contactors and a dilute plasma.

Patterson, Michael J.; Wilbur, Paul J.

1986-01-01

198

Plasma contactors for electrodynamic tether  

NASA Astrophysics Data System (ADS)

The role plasma contactors play in effective electrodynamic tether operation is discussed. Hollow cathodes and hollow cathode-based plasma sources have been identified as leading candidates for the electrodynamic tether plasma contactor. Present experimental efforts to evaluate the suitability of these devices as plasma contactors, conducted concurrently at NASA Lewis Research Center and Colorado State University, are reviewed. These research programs include the definition of preliminary plasma contactor designs, and the characterization of their operation both as electron emitters and electron collectors to and from a simulated space plasma. Results indicate that ampere-level electron currents, sufficient for electrodynamic tether operation, can be exchanged between hollow cathode-based plasma contactors and a dilute plasma.

Patterson, Michael J.; Wilbur, Paul J.

1986-09-01

199

Suspension and solution plasma spraying  

NASA Astrophysics Data System (ADS)

Suspension and solution plasma spraying makes it possible to achieve coatings with fine microstructural features and is becoming a common route in laboratories to elaborate coatings a few tenths to a few hundreds of micrometres thick. This paper presents the recent developments in direct current plasma spraying of suspensions or solutions. It begins with a short description of the main plasma torches used for liquid feedstock spraying as well as the techniques used to experimentally observe droplets and particles in the plasma jet and characterize the void network of nanostructured plasma-sprayed coatings. The paper then turns to the momentum and heat transfers between fine particles and the plasma jet and the interactions between the plasma jet and a liquid in the form of a jet or drops. It concludes by linking some characteristic features of coating microstructures with the liquid processing in the plasma jet.

Fauchais, P.; Joulia, A.; Goutier, S.; Chazelas, C.; Vardelle, M.; Vardelle, A.; Rossignol, S.

2013-06-01

200

A plasma receiving dipole antenna  

SciTech Connect

Results from experimental studies of a short-wave plasma dipole transceiver antenna are presented. The efficiency of the plasma receiving antenna is estimated, and the optimal frequency range for excitation and reception under the given experimental conditions is determined.

Minaev, I. M.; Gusein-zade, N. G. [Russian Academy of Sciences, Prokhorov Institute of General Physics (Russian Federation); Rukhadze, K. Z. [Moscow State Institute of Radio Engineering, Electronics, and Automation (Russian Federation)

2010-10-15

201

Fundamentals of Plasma Physics  

Microsoft Academic Search

The widespread importance of plasmas in many areas of contemporary physics makes good textbooks in the field that are both introductory and comprehensive invaluable. This new book by Paul Bellen from CalTech by and large meets these goals. It covers the traditional textbook topics such as particle orbits, the derivation of the MHD equations from Vlasov theory, cold and warm

P J Cargill

2007-01-01

202

Computations in Plasma Physics.  

ERIC Educational Resources Information Center

Discusses contributions of computers to research in magnetic and inertial-confinement fusion, charged-particle-beam propogation, and space sciences. Considers use in design/control of laboratory and spacecraft experiments and in data acquisition; and reviews major plasma computational methods and some of the important physics problems they…

Cohen, Bruce I.; Killeen, John

1983-01-01

203

Implicit plasma simulation  

SciTech Connect

Implicit time integration methods have been used extensively in numerical modelling of slowly varying phenomena in systems that also support rapid variation. Examples include diffusion, hydrodynamics and reaction kinetics. This article discussed implementation of implicit time integration in plasma codes of the ''particle-in-cell'' family, and the benefits to be gained.

Langdon, A.B.

1985-03-03

204

Fission in Stellar Plasma  

Microsoft Academic Search

The fission of heavy nuclides is examined in a dense stellar plasma. The correction in the Coulomb energy due to the interaction between the ion and the induced-electron charge density affects the process of fission and reduces the fission barrier depending upon the physical situation. Shell- and surface-symmetry effects are included in the calculation of the fission barrier as a

K. Duorah; H. L. Duorah

1973-01-01

205

Internal magnetospheric plasma flow  

NASA Technical Reports Server (NTRS)

Experimental evidence indicates that there exist at least two separate circulation patterns within the magnetosphere which allow cold heavy plasmaspheric ions, which drift toward the dayside magnetopause, to be transported to the plasma sheet for acceleration and reinjection into the inner magnetosphere. The first of these results in the ions being transported over the polar regions in the plasma mantle. The mantle ultimately joins the plasma sheet at great distance in the tail via the lobe electric field. The second circulation pattern is embodied in the low latitude boundary layer. Recent data show that the extension of the low latitude boundary layer in the tail at 60 Earth radii turns inward to directly feed the plasma sheet. A means of estimating the fractional role played by each is to compare the electric potential drop across the low latitude boundary layer with the total cross tail convection electric potential. This was done for a set of tail crossings using ALSEP/SIDE data. The result is that the boundary layer contains about 20% of the potential drop across the tail.

Freeman, J. W.

1979-01-01

206

Plasma antioxidants from chocolate  

Microsoft Academic Search

There is some speculation that dietary flavonoids from chocolate, in particular (-)epicatechin, may promote cardiovascular health as a result of direct antioxidant effects or through antithrombotic mechanisms. Here we show that consumption of plain, dark chocolate (Fig. 1) results in an increase in both the total antioxidant capacity and the (-)epicatechin content of blood plasma, but that these effects are

Mauro Serafini; Rossana Bugianesi; Giuseppe Maiani; Silvia Valtuena; Simone De Santis; Alan Crozier

2003-01-01

207

A Plasma Display Terminal.  

ERIC Educational Resources Information Center

A graphics terminal designed for use as a remote computer input/output terminal is described. Although the terminal is intended for use in teaching applications, it has several features which make it useful in many other computer terminal applications. These features include: a 10-inch square plasma display panel, permanent storage of information…

Stifle, Jack

208

Periodically oscillating plasma sphere  

Microsoft Academic Search

The periodically oscillating plasma sphere, or POPS, is a novel fusion concept first proposed by D. C. Barnes and R. A. Nebel [Fusion Technol. 38, 28 (1998)]. POPS utilizes the self-similar collapse of an oscillating ion cloud in a spherical harmonic oscillator potential well formed by electron injection. Once the ions have been phase-locked, their coherent motion simultaneously produces very

R. A. Nebel; S. Stange; S. Krupakar Murali

2005-01-01

209

Nuclear envelope Plasma membrane  

E-print Network

p JAKP LMB NPC Nuclear envelope Plasma membrane crm1 NF- B NF-B Stattic STAT3 A STAT3-decoy to co-immunoprecipitate with importin. Leptomycin B and vanadate both trap STAT3 in the nucleus potential of STAT3-decoy ODN as a reagent and to STAT3 nucleo-cytoplasmic shuttling in tumor cells

Paris-Sud XI, Université de

210

Electrostatic Plasma Accelerator (EPA)  

NASA Technical Reports Server (NTRS)

The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass. The goal of the present program is to demonstrate feasibility of the EPA thruster concept through experimental and theoretical investigations of the EPA acceleration mechanism and discharge chamber performance. Experimental investigations will include operating the test bed ion (TBI) engine as an EPA thruster and parametrically varying the thruster geometry and operating conditions to quantify the electrostatic plasma acceleration effect. The theoretical investigations will include the development of a discharge chamber model which describes the relationships between the engine size, plasma properties, and overall performance. For the EPA thruster to be a viable propulsion concept, overall thruster efficiencies approaching 30% with specific impulses approaching 1000 s must be achieved.

Brophy, John R.; Aston, Graeme

1989-01-01

211

Pulverized coal plasma gasification  

Microsoft Academic Search

A number of experiments on the plasma-vapor gasification of brown coals of three types have been carried out using an experimental plant with an electric-arc reactor of the combined type. On the basis of the material and heat balances, process parameters have been obtained: the degree of carbon gasification (?c), the level of sulfur conversion into the gas phase (?s),

R. A. Kalinenko; A. P. Kuznetsov; A. A. Levitsky; V. E. Messerle; Yu. A. Mirokhin; L. S. Polak; Z. B. Sakipov; A. B. Ustimenko

1993-01-01

212

Dissipation in intercluster plasma  

E-print Network

We discuss dissipative processes in strongly gyrotropic, nearly collisionless plasma in clusters of galaxies (ICM). First, we point out that Braginsky theory, which assumes that collisions are more frequent that the system's dynamical time scale, is inapplicable to fast, sub-viscous ICM motion. Most importantly, the electron contribution to collisional magneto-viscosity dominates over that of ions for short-scale Alfvenic motions. Thus, if a turbulent cascade develops in the ICM and propagates down to scales $\\leq 1$ kpc, it is damped collisionally not on ions, but on electrons. Second, in high beta plasma of ICM, small variations of the magnetic field strength, of relative value $\\sim 1/\\beta$, lead to development of anisotropic pressure instabilities (firehose, mirror and cyclotron). Unstable wave modes may provide additional resonant scattering of particles, effectively keeping the plasma in a state of marginal stability. We show that in this case the dissipation rate of a laminar, subsonic, incompressible flows scales as inverse of plasma beta parameter. We discuss application to the problem of ICM heating.

Maxim Lyutikov

2007-09-11

213

Plasma based accelerators  

SciTech Connect

A plasma medium can support a variety of wave motions which may be useful for accelerating charged particles. For highly relativistic beams the longitudinal electrostatic wave is most suitable and may be driven by laser or by particle beams. The basic principles, limitations and prospects for these devices are discussed.

Evans, R.G.

1987-05-05

214

Vacuum plasma spray coating  

NASA Technical Reports Server (NTRS)

Currently, protective plasma spray coatings are applied to space shuttle main engine turbine blades of high-performance nickel alloys by an air plasma spray process. Originally, a ceramic coating of yttria-stabilized zirconia (ZrO2.12Y2O3) was applied for thermal protection, but was removed because of severe spalling. In vacuum plasma spray coating, plasma coatings of nickel-chromium-aluminum-yttrium (NiCrAlY) are applied in a reduced atmosphere of argon/helium. These enhanced coatings showed no spalling after 40 MSFC burner rig thermal shock cycles between 927 C (1700 F) and -253 C (-423 F), while current coatings spalled during 5 to 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2.8Y2O3 to the turbine blades of first-stage high-pressure fuel turbopumps utilizing the enhanced NiCrAlY bond-coating process. NiCrAlY bond coating is applied first, with ZrO2.8Y2O3 added sequentially in increasing amounts until a thermal barrier coating is obtained. The enchanced thermal barrier coating has successfully passed 40 burner rig thermal shock cycles.

Holmes, Richard R.; Mckechnie, Timothy N.

1989-01-01

215

Quark gluon plasma  

Microsoft Academic Search

Recent trends in the research of quark gluon plasma (QGP) are surveyed and the current experimental and theoretical status\\u000a regarding the properties and signals of QGP is reported. We hope that the experiments commencing at relativistic heavy-ion\\u000a collider (RHIC) in 2000 will provide a glimpse of the QGP formation.

C P Singh

2000-01-01

216

Rational paradigm of plasma physics  

Microsoft Academic Search

In recent studies we have multiply envisioned the irrationality of the traditional plasma kinetis [1--5]. Its basic false cornerstone was shown to be the substitution of real plasmas by plasma probabilistic ensembles [1--3]. We have created culture of plasma studies with refrain from an ensemble substitution [1-8]. We discovered intense decay of Langmuir quanta, as opposite to traditional deduction of

Vasily Erofeev

2004-01-01

217

Time Dependence in Plasma Codes  

E-print Network

Time-dependent plasma codes are a natural extension of static nonequilibrium plasma codes. Comparing relevant timescales will determine whether or not time-dependent treatment is necessary. In this article I outline the ingredients for a time-dependent plasma code in a homogeneous medium and discuss the computational method. In the second half of the article I describe recombination in the early Universe as a detailed example of a problem whose solution requires a time-dependent plasma code.

S. Seager

2001-06-12

218

Overview of Plasma Edge Physics  

SciTech Connect

Basic properties of the plasma edge in magnetically confined fusion plasmas are summarised. Starting from the magnetic topology of tokamaks we describe the transport of the scrape-off layer including drifts and the consequences of the electrostatic Debye sheath in front of the plasma facing components. The relation between the local plasma density and temperature at the targets and the fluxes of power and particles in the SOL is discussed. The transport of the fuel neutrals (hydrogen atoms and molecules) is described.

Unterberg, Bernhard; Samm, Ulrich

2004-03-15

219

Millimeter Wave Communication through Plasma  

NASA Technical Reports Server (NTRS)

Millimeter wave communication through plasma at frequencies of 35 GHz or higher shows promise in maintaining communications connectivity during rocket launch and re-entry, critical events which are typically plagued with communication dropouts. Extensive prior research into plasmas has characterized the plasma frequency at these events, and research at the Kennedy Space Center is investigating the feasibility of millimeter communication through these plasma frequencies.

Bastin, Gary L.

2008-01-01

220

PLASMA PHYSICS & RADIATION TECHNOLOGY Dutch Physical Society  

E-print Network

22nd SYMPOSIUM PLASMA PHYSICS & RADIATION TECHNOLOGY Dutch Physical Society Section Plasma and Gas Discharge Physics & Research school Center for Plasma Physics and Radiation Technology Nederlandse collaboration with the research school `Center for Plasma Physics and Radiation Technology' Members

Eindhoven, Technische Universiteit

221

Twenty years of plasma physics  

Microsoft Academic Search

The first major activity at the International Centre for Theoretical Physics was the International Seminar on Plasma Physics held in Trieste from October 5-31, 1964, followed in 1965 by a highly successful full year's working group activity in plasma theory. This volume, Twenty Years of Plasma Physics, represents a commemoration of the 1964 Seminar, hopefully will be similarly useful, and

Mc Namara

1985-01-01

222

Plasma physics: an introductory course  

Microsoft Academic Search

This book has been developed from lectures given at the Culham summer schools in plasma physics, and provides a wide-ranging introduction to the theoretical and experimental study of plasmas and their applications. The first few chapters deal with the fundamentals of plasma physics, covering such topics as particle dynamics, kinetic theory, waves and magnetohydrodynamics. Subsequent chapters describe the applications and

R. O. Dendy

1993-01-01

223

Plasma Physics John F. Kennedy  

E-print Network

v v v v v Princeton Plasma Physics Laboratory N 278 95 1 95 18 NEW YORK John F. Kennedy Int Campus/ Sayre Drive Sign PPPLSayre Dr. Location: Princeton Plasma Physics Laboratory James Forrestal Campus U.S. Route #1 North at Sayre Drive Plainsboro, NJ 08536 Mailing Address: Princeton Plasma Physics

Princeton Plasma Physics Laboratory

224

Plasma Physics for Nuclear Fusion  

Microsoft Academic Search

The book focuses on the properties of gaseous plasmas needed in the attainment of controlled fusion reactions. The first five chapters develop the fundamentals of plasma physics and present the conditions of nuclear fusion reactions. The next four provide a magnetohydrodynamic description of plasmas, followed by four chapters that explain wave phenomena and instabilities by means of a kinetic model.

K. Miyamoto; Robert L. Dewar

1980-01-01

225

White Paper on Dusty Plasmas.  

National Technical Information Service (NTIS)

Dusty plasmas is the name given to plasmas heavily laden with charged dust grains which together with the surrounding ions and electrons constitute a kind of plasma regime. This field of study is receiving increased attention because of the observation of...

E. C. Whipple

1986-01-01

226

Turbulence & Transport in Burning Plasmas  

E-print Network

microturbulence through direct numerical sumulation · National Team (& four codes): ­ GA (Waltz, Candy) ­ U. MD to reduce it (reversed magnetic shear, sheared flows, plasma shaping...) · Several good ideas plasma turbulence being developed by Plasma Microturbulence Project. Candy & Waltz (GA) movies shown: d3d

227

Relativistic thermal plasmas Susan Stepney  

E-print Network

Relativistic thermal plasmas by Susan Stepney Institute of Astronomy and Newnham College University Summary The study of relativistic thermal plasmas, where 2 e ekT m c , is of growing importance the development of a computer program to model a thermal plasma slab at mildly relativistic temperatures. I

Stepney, Susan

228

TOPICAL REVIEW: Thermal plasma modelling  

Microsoft Academic Search

Electrical arcs and, more generally thermal plasmas, are widely used in many applications and the understanding or the improvement of the corresponding processes or systems, often requires precise modelling of the plasma. We present, here, a double approach to thermal plasma modelling, which combines the scientific procedure with an engineering point of view. First, we present the fundamental properties of

A. Gleizes; J. J. Gonzalez; P. Freton

2005-01-01

229

Magnetic Lens For Plasma Engine  

NASA Technical Reports Server (NTRS)

Low-field electromagnet coils placed downstream of plasma engine, polarized oppositely to higher-field but smaller radius coil in nozzle of engine, reduces divergence of plasma jet, thereby increasing efficiency of engine. Concept tested by computer simulation based on simplified mathematical model of plasma, engine, and coils.

Sercel, Joel C.

1992-01-01

230

High-power radiating plasma  

NASA Technical Reports Server (NTRS)

The physical principles underlying the use of radiating plasmas for the optical pumping of lasers are described. Particular consideration is given to the properties of radiating plasmas; radiation selectivity; the dynamics, equilibrium, and stability of radiating plasmas; the radiative Reynolds number; and experimental results on radiating discharges.

Rozanov, V. B.; Rukhadze, A. A.

1984-01-01

231

Plasma chemistry and its applications  

NASA Technical Reports Server (NTRS)

The relationship between discharge phenomena and plasma chemistry, as well as the equipment and mechanisms of plasma chemical reactions are described. Various areas in which plasma chemistry is applied are surveyed, such as: manufacturing of semiconductor integrated circuits; synthetic fibers; high polymer materials for medical uses; optical lenses; and membrane filters (reverse penetration films).

Hozumi, K.

1980-01-01

232

Michigan Institute for Plasma Sci-  

E-print Network

-thermal plasma interaction with living tissue. Engineering research has resulted in many advances in healthcare of a revolu- tionary new branch of engineering medicine ­ Plasma Medicine. The success of Plasma Medicine Professorship, DuPont Award for Outstanding Achievements in Chemistry, Chernobyl Award, Kurchatov Gold Medal

Shyy, Wei

233

The Galileo Plasma wave investigation  

Microsoft Academic Search

The purpose of the Galileo plasma wave investigation is to study plasma waves and radio emissions in the magnetosphere of Jupiter. The plasma wave instrument uses an electric dipole antenna to detect electric fields, and two search coil magnetic antennas to detect magnetic fields. The frequency range covered is 5 Hz to 5.6 MHz for electric fields and 5 Hz

D. A. Gurnett; W. S. Kurth; R. R. Shaw; A. Roux; R. Gendrin; C. F. Kennel; F. L. Scarf; S. D. Shawhan

1992-01-01

234

Controlled zone microwave plasma system  

DOEpatents

An apparatus and method for initiating a process gas plasma. A conductive plate having a plurality of conductive fingers is positioned in a microwave applicator. An arc forms between the conductive fingers to initiate the formation of a plasma. A transport mechanism may convey process materials through the plasma. A spray port may be provided to expel processed materials.

Ripley, Edward B. (Knoxville, TN); Seals, Roland D. (Oak Ridge, TN); Morrell, Jonathan S. (Knoxville, TN)

2009-10-20

235

Depletion of Abundant Plasma Proteins and Limitations of Plasma Proteomics  

PubMed Central

Immunoaffinity depletion with antibodies to the top 7 or top 14 high abundance plasma proteins is used to enhance detection of lower abundance proteins in both shotgun and targeted proteomic analyses. We evaluated the effects of top 7/top 14 immunodepletion on the shotgun proteomic analysis of human plasma. Our goal was to evaluate the impact of immunodepletion on detection of proteins across detectable ranges of abundance. The depletion columns afforded highly repeatable and efficient plasma protein fractionation. Relatively few nontargeted proteins were captured by the depletion columns. Analyses of unfractionated and immunodepleted plasma by peptide isoelectric focusing (IEF), followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) demonstrated enrichment of nontargeted plasma proteins by an average of 4-fold, as assessed by MS/MS spectral counting. Either top 7 or top 14 immunodepletion resulted in a 25% increase in identified proteins compared to unfractionated plasma. Although 23 low abundance (<10 ng mL?1) plasma proteins were detected, they accounted for only 5–6% of total protein identifications in immunodepleted plasma. In both unfractionated and immunodepleted plasma, the 50 most abundant plasma proteins accounted for 90% of cumulative spectral counts and precursor ion intensities, leaving little capacity to sample lower abundance proteins. Untargeted proteomic analyses using current LC-MS/MS platforms—even with immunodepletion—cannot be expected to efficiently discover low abundance, disease-specific biomarkers in plasma. PMID:20677825

Tu, Chengjian; Rudnick, Paul A.; Martinez, Misti Y.; Cheek, Kristin L.; Stein, Stephen E.; Slebos, Robbert J. C.; Liebler, Daniel C.

2010-01-01

236

Plasma dynamics in microsecond megaampere plasma opening switches  

SciTech Connect

The paper considers the transport of a magnetic field in highly ionized plasma of microsecond megaampere plasma opening switches. Self-similar solutions for plasma aggregation by a linearly increasing magnetic field are derived. For these solutions, the magnetic field energy in the current channel is much lower than the energy of the accelerated plasma flow. The effect of Joule heating of the plasma becomes profound only with a uniform current density. It is shown that the evolution of the magnetic field in the accelerated flow is reduced to diffusion with an effective electrical conductivity proportional to the harmonic average of the Spitzer conductivity and conductivity dependent on the magnetic field in the current channel. Thus, during about the first 100 ns of the current pulse the conductivity of the current channel increases due to the plasma heating and, as the plasma is accelerated, its conductivity decreases.

Loginov, S. V. [Institute of High Current Electronics SB RAS, Tomsk 634055 (Russian Federation)

2011-10-15

237

Experimental Plasma Research project summaries  

SciTech Connect

This report contains descriptions of the activities supported by the Experimental Plasma Research Branch of APP. The individual project summaries were prepared by the principal investigators and include objectives and milestones for each project. The projects are arranged in six research categories: Plasma Properties; Plasma Heating; Plasma Diagnostics; Atomic, Molecular and Nuclear Physics; Advanced Superconducting Materials; and the Fusion Plasma Research Facility (FPRF). Each category is introduced with a statement of objectives and recent progress and followed by descriptions of individual projects. An overall budget summary is provided at the beginning of the report.

None

1980-09-01

238

Closed inductively coupled plasma cell  

DOEpatents

A closed inductively coupled plasma cell generates a relatively high power, low noise plasma for use in spectroscopic studies is disclosed. A variety of gases can be selected to form the plasma to minimize spectroscopic interference and to provide a electron density and temperature range for the sample to be analyzed. Grounded conductors are placed at the tube ends and axially displaced from the inductive coil, whereby the resulting electromagnetic field acts to elongate the plasma in the tube. Sample materials can be injected in the plasma to be excited for spectroscopy. 1 fig.

Manning, T.J.; Palmer, B.A.; Hof, D.E.

1990-11-06

239

On description of quantum plasma  

E-print Network

A plasma becomes quantum when the quantum nature of its particles significantly affects its macroscopic properties. To answer the question of when the collective quantum plasma effects are important, a proper description of such effects is necessary. We consider here the most common methods of description of quantum plasma, along with the related assumptions and applicability limits. In particular, we analyze in detail the hydrodynamic description of quantum plasma, as well as discuss some kinetic features of analytic properties of linear dielectric response function in quantum plasma. We point out the most important, in our view, fundamental problems occurring already in the linear approximation and requiring further investigation. (submitted to Physics-Uspekhi)

S. V. Vladimirov; Yu. O. Tyshetskiy

2011-01-20

240

Plasma chemistry for inorganic materials  

NASA Technical Reports Server (NTRS)

Practical application of plasma chemistry to the development of inorganic materials using both low temperature and warm plasmas are summarized. Topics cover: the surface nitrification and oxidation of metals; chemical vapor deposition; formation of minute oxide particles; the composition of oxides from chloride vapor; the composition of carbides and nitrides; freezing high temperature phases by plasma arc welding and plasma jet; use of plasma in the development of a substitute for petroleum; the production of silicon for use in solar cell batteries; and insulating the inner surface of nuclear fusion reactor walls.

Matsumoto, O.

1980-01-01

241

Plasmas in the earth's magnetotail  

NASA Technical Reports Server (NTRS)

An overview of the general charcteristics of plasmas within the earth's magnetotail and its environs is presented. Present knowledge of the plasma within these regions as gained via in situ measurements provides the general theme, although observations of magnetic fields, energetic particles and plasma waves are included in the discussion. Primary plasma regimes in the magnetotail are the plasma sheet, its boundary layer, the magnetotail lobes, the boundary layer at the magnetopause and the distant magnetotail. Although great progress in the understanding of these regions is evident in the literature of the past several years, many of their features remain as exciting enigmas to be resolved by future observational and theoretical investigation.

Frank, L. A.

1985-01-01

242

Atmospheric-pressure plasma technology  

NASA Astrophysics Data System (ADS)

Major industrial plasma processes operating close to atmospheric pressure are discussed. Applications of thermal plasmas include electric arc furnaces and plasma torches for generation of powders, for spraying refractory materials, for cutting and welding and for destruction of hazardous waste. Other applications include miniature circuit breakers and electrical discharge machining. Non-equilibrium cold plasmas at atmospheric pressure are obtained in corona discharges used in electrostatic precipitators and in dielectric-barrier discharges used for generation of ozone, for pollution control and for surface treatment. More recent applications include UV excimer lamps, mercury-free fluorescent lamps and flat plasma displays.

Kogelschatz, U.

2004-12-01

243

Closed inductively coupled plasma cell  

DOEpatents

A closed inductively coupled plasma cell generates a relatively high power, low noise plasma for use in spectroscopic studies. A variety of gases can be selected to form the plasma to minimize spectroscopic interference and to provide a electron density and temperature range for the sample to be analyzed. Grounded conductors are placed at the tube ends and axially displaced from the inductive coil, whereby the resulting electromagnetic field acts to elongate the plasma in the tube. Sample materials can be injected in the plasma to be excited for spectroscopy.

Manning, Thomas J. (Gainesville, FL); Palmer, Byron A. (Los Alamos, NM); Hof, Douglas E. (Santa Fe, NM)

1990-01-01

244

Transport processes in space plasmas  

SciTech Connect

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project represents a comprehensive research effort to study plasma and field transport processes relevant for solar-terrestrial interaction, involving the solar wind and imbedded magnetic field and plasma structures, the bow shock of the Earth`s magnetosphere and associated waves, the Earth`s magnetopause with imbedded flux rope structures and their connection with the Earth, plasma flow in the Earth`s magnetotail, and ionospheric beam/wave interactions. The focus of the work was on the interaction between plasma and magnetic and electric fields in the regions where different plasma populations exist adjacent to or superposed on each other. These are the regions of particularly dynamic plasma behavior, important for plasma and energy transport and rapid energy releases. The research addressed questions about how this interaction takes place, what waves, instabilities, and particle/field interactions are involved, how the penetration of plasma and energy through characteristic boundaries takes place, and how the characteristic properties of the plasmas and fields of the different populations influence each other on different spatial and temporal scales. These topics were investigated through combining efforts in the analysis of plasma and field data obtained through space missions with theory and computer simulations of the plasma behavior.

Birn, J.; Elphic, R.C.; Feldman, W.C. [and others

1997-08-01

245

Main Features of Plasma Control  

SciTech Connect

In the recent years Plasma Control has always increased his importance in any advanced experiment. It is now clear that ITER will not be able to operate without a quite advanced and sophisticated control apparatus. Necessarily this system will have to integrate several different aspects of the Plasma behavior. One of the most important parts of a closed loop control system is the quality of the measurement of the plasma parameters that should be controlled. Eventually, this aspect involves sophisticated and complex diagnostic apparatus. This paper presents an overview of the present status, and further studies and developments needed, in the next future, for the design and realization of an integrated plasma control system aimed at both stabilizing the plasma non-axisymmetric instabilities and controlling the most important internal plasma parameters. In particular the Edge Localized Modes (ELMs), the Neo-Classical Tearing Modes (NTM), the Resistive Wall Mode (RWM) and the Plasma Profiles control system necessities will be shortly illustrated.

Crisanti, F. [Associazione Euratom-ENEA sulla Fusione, Frascati, C.P. 65, 00044 Frascati (Italy); Albanese, R.; Ambrosino, G. [Associazione EURATOM/ENEA/CREATE, Univ. Napoli Federico II, Via Claudio21, 80125 Napoli (Italy)

2008-03-12

246

Plasma contactors for electrodynamic tethers  

NASA Astrophysics Data System (ADS)

Plasma contactors could be used to ground satellites to space plasma to acquire a flow of electrons to propel or power the satellites. A tether would cut across geomagnetic field lines, producing a potential difference between the ends of the tether. Closing the connection between the ends would form a circuit in which an electrical load could be inserted. Design constraints of the circuit are low impedance and a fully reversible high current. The contactor would generate a neutral plasma to connect to the ionospheric plasma. The surface area of the connection would have to be kept large enough for the current density to be equal to the random electron current density in the unperturbed space plasmas. The other contactor would feed electrons and draw ions from the space plasma. Experimental results from spaceborne and ground-based space plasma simulator tests of hollow cathodes that have shown that multiampere currents can be collected are described.

Patterson, Michael J.; Wilbur, Paul J.

1987-02-01

247

Space plasma contractor research, 1988  

NASA Astrophysics Data System (ADS)

Results of experiments conducted on hollow cathode-based plasma contractors are reported. Specific tests in which attempts were made to vary plasma conditions in the simulated ionospheric plasma are described. Experimental results showing the effects of contractor flowrate and ion collecting surface size on contactor performance and contactor plasma plume geometry are presented. In addition to this work, one-dimensional solutions to spherical and cylindircal space-charge limited double-sheath problems are developed. A technique is proposed that can be used to apply these solutions to the problem of current flow through elongated double-sheaths that separate two cold plasmas. Two conference papers which describe the essential features of the plasma contacting process and present data that should facilitate calibration of comprehensive numerical models of the plasma contacting process are also included.

Williams, John D.; Wilbur, Paul J.

1989-02-01

248

Space plasma contractor research, 1988  

NASA Technical Reports Server (NTRS)

Results of experiments conducted on hollow cathode-based plasma contractors are reported. Specific tests in which attempts were made to vary plasma conditions in the simulated ionospheric plasma are described. Experimental results showing the effects of contractor flowrate and ion collecting surface size on contactor performance and contactor plasma plume geometry are presented. In addition to this work, one-dimensional solutions to spherical and cylindircal space-charge limited double-sheath problems are developed. A technique is proposed that can be used to apply these solutions to the problem of current flow through elongated double-sheaths that separate two cold plasmas. Two conference papers which describe the essential features of the plasma contacting process and present data that should facilitate calibration of comprehensive numerical models of the plasma contacting process are also included.

Williams, John D.; Wilbur, Paul J.

1989-01-01

249

Plasma injection and diamagnetism  

NASA Technical Reports Server (NTRS)

A detailed study of the diamagnetic properties of magnetospheric plasma injected at synchronous altitudes is presented. Defining the magnetic induction field B = H + 4piM, the magnetization M is computed from the plasma distribution functions and it is shown that the diamagnetic contribution of the particles having energies of 100 eV to 81 eV can completely account for observed changes in the magnetic induction energy density. Computation of the resulting magnetic field H indicates that the current system in the magnetosphere is complex. Significant changes in H have been observed in a few minutes time scale. Studies of the particle density at various magnetic moments show that both protons and electrons together or individually act to cause the diamagnetic variations in B.

Gurgiolo, C.; Lin, C. S.; Mauk, B.; Parks, G. K.; Mcilwain, C.

1979-01-01

250

Plasma dust crystallization  

NASA Technical Reports Server (NTRS)

In a ground-based definition study, a concept for a new type of microgravity experiment is developed. We formed a new state of matter: a crystalline lattice structure of charged micron-size spheres, suspended in a charge-neutral plasma. The plasma is formed by a low-pressure radio-frequency argon discharge. Solid microspheres are introduced, and they gain a negative electric charge. They are cooled by molecular drag on the ambient neutral gas. They are detected by laser light scattering and video photography. Laboratory experiments have demonstrated that a two-dimensional nonquantum lattice forms through the Coulomb interaction of these spheres. Microgravity is thought to be required to observe a three-dimensional structure.

Goree, John; Thomas, H.; Morfill, G.

1994-01-01

251

Localized Plasma Balls  

E-print Network

In this paper we numerically construct localised black hole solutions at the IR bottom of the confining geometry of the AdS soliton. These black holes should be thought as the finite size analogues of the domain wall solutions that have appeared previously in the literature. From the dual CFT point of view, these black holes correspond to finite size balls of deconfined plasma surrounded by the confining vacuum. The plasma ball solutions are parametrised by the temperature. For temperatures well above the deconfinement transition, the dual black holes are small and round and they are well-described by the asymptotically flat Schwarzschild solution. On the other hand, as the temperature approaches the deconfinement temperature, the black holes look like pancakes which are extended along the IR bottom of the space-time. On top of these backgrounds, we compute various probes of confinement/deconfinement such as temporal Wilson loops and entanglement entropy.

Pau Figueras; Saran Tunyasuvunakool

2014-03-31

252

Localized Plasma Balls  

E-print Network

In this paper we numerically construct localised black hole solutions at the IR bottom of the confining geometry of the AdS soliton. These black holes should be thought as the finite size analogues of the domain wall solutions that have appeared previously in the literature. From the dual CFT point of view, these black holes correspond to finite size balls of deconfined plasma surrounded by the confining vacuum. The plasma ball solutions are parametrised by the temperature. For temperatures well above the deconfinement transition, the dual black holes are small and round and they are well-described by the asymptotically flat Schwarzschild solution. On the other hand, as the temperature approaches the deconfinement temperature, the black holes look like pancakes which are extended along the IR bottom of the space-time. On top of these backgrounds, we compute various probes of confinement/deconfinement such as temporal Wilson loops and entanglement entropy.

Figueras, Pau

2014-01-01

253

Plasma Properties of Microwave Produced Plasma in a Toroidal Device  

NASA Astrophysics Data System (ADS)

We have modified a small tokamak, STOR-1M, on loan from University of Saskatchewan, to operate as a low-temperature (˜5 eV) toroidal plasma machine with externally induced toroidal magnetic fields ranging from zero to ˜50 G. The plasma is produced using microwave discharges at relatively high pressures. Microwaves are produced by a kitchen microwave-oven magnetron operating at 2.45 GHz in continuous operating mode, resulting in pulses ˜0.5 s in duration. Initial measurements of plasma formation in this device with and without applied magnetic fields are presented. Plasma density and temperature profiles have been measured using Langmuir probes and the magnetic field profile inside the plasma has been obtained using Hall probes. When the discharge is created with no applied toroidal magnetic field, the plasma does not fill the entire torus due to high background pressure. However, when a toroidal magnetic field is applied, the plasma flows along the applied field, filling the torus. Increasing the applied magnetic field seems to aid plasma formation - the peak density increases and the density gradient becomes steeper. Above a threshold magnetic field, the plasma develops low-frequency density oscillations due to probable excitation of flute modes in the plasma.

Singh, Ajay; Edwards, W. F.; Held, Eric

2011-11-01

254

Experimental investigations of plasma perturbation in Thomson scattering applied to thermal plasma diagnostics  

E-print Network

Experimental investigations of plasma perturbation in Thomson scattering applied to thermal plasma ns laser pulses were performed on argon thermal discharge plasma with electron temperature Te 10 000 discharge plasmas 1�5 , laser-induced plasmas 6�9 , pinch plasmas 10�12 , but also to study thermal plasmas

255

Diamagnetism in a plasma  

SciTech Connect

This is an extension of a study of electric currents and force balance orthogonal to a unidirectional magnetic field of induction ({bold B}) in a collisionless plasma [K. D. Cole, Phys. Plasmas {bold 3}, 2717 (1996)]. All quantities are assumed to vary only in one direction orthogonal to {bold B}. Two new concepts are introduced, which are not in conventional plasma physics. First a magnetic polarization effect corresponding to electric polarization is found. This defines a contribution to the magnetic moment per unit volume of {minus}{rho}{sub m}c{sup 2}E{sup 2}/B{sup 3}. Second the conduction current is defined in terms of the curl of the magnetic field intensity {bold H}, in accordance with Maxwell. In this scheme, when there is no electric field, (1/4{pi})({partial_derivative}H/{partial_derivative}z)B+({partial_derivative}p{sub {perpendicular}}/{partial_derivative}z)=0, instead of the conventional equation with B/{mu}{sub 0} in place of H. In both schemes, j{times}B{minus}{bold {del}}p{sub {perpendicular}}=0. Though this makes no difference to the electric current intensity calculated in the two schemes, and no difference to the force balance equation, it makes a significant difference to the relationship between B and p{sub {perpendicular}} in many plasma conditions of interest. When the electric field is nonzero, the situation is more complex. It is shown that the new diamagnetism of this paper and the dielectric current of the earlier one are consistent with special relativity. Some applications of the theory are discussed. {copyright} {ital 1997 American Institute of Physics.}

Cole, K.D. [National Aeronautics and Space Administration, Goddard Space Flight Center, Code 910.4, Greenbelt, Maryland 20771 (United States)] [National Aeronautics and Space Administration, Goddard Space Flight Center, Code 910.4, Greenbelt, Maryland 20771 (United States)

1997-06-01

256

Princeton Plasma Physics Laboratory:  

SciTech Connect

This paper discusses progress on experiments at the Princeton Plasma Physics Laboratory. The projects and areas discussed are: Principal Parameters Achieved in Experimental Devices, Tokamak Fusion Test Reactor, Princeton Large Torus, Princeton Beta Experiment, S-1 Spheromak, Current-Drive Experiment, X-ray Laser Studies, Theoretical Division, Tokamak Modeling, Spacecraft Glow Experiment, Compact Ignition Tokamak, Engineering Department, Project Planning and Safety Office, Quality Assurance and Reliability, and Administrative Operations.

Phillips, C.A. (ed.)

1986-01-01

257

Progress in plasma carburizing  

Microsoft Academic Search

Experiments on high-rate carburizing in a dc glow-discharge plasma were extended to cover a broader range of temperature,\\u000a carburizing gases, and steel compositions. Results show that the enhanced carburizing rate observed with methane is also obtained\\u000a with its heavier homologues over the temperature range explored. The efficiency at which the carburizing gas is utilized during\\u000a the carburizing stage was measured

William L. Grube

1980-01-01

258

PLASMA CELL LEUKEMIA  

PubMed Central

Plasma cell leukemia (PCL) is a rare and aggressive variant of myeloma characterized by the presence of circulating plasma cells. It is classified as either primary PCL occurring at diagnosis or as secondary PCL in patients with relapsed/refractory myeloma. Primary PCL is a distinct clinic-pathologic entity with different cytogenetic and molecular findings. The clinical course is aggressive with short remissions and survival duration. The diagnosis is based upon the percentage (? 20%) and absolute number (? 2 × 10 9/L) of plasma cells in the peripheral blood. It is proposed that the thresholds for diagnosis be reexamined and consensus recommendations are made for diagnosis, as well as, response and progression criteria. Induction therapy needs to begin promptly and have high clinical activity leading to rapid disease control in an effort to minimize the risk of early death. Intensive chemotherapy regimens and bortezomib-based regimens are recommended followed by high-dose therapy with autologous stem-cell transplantation (HDT/ASCT) if feasible. Allogeneic transplantation can be considered in younger patients. Prospective multicenter studies are required to provide revised definitions and better understanding of the pathogenesis of PCL. PMID:23288300

de Larrea, Carlos Fernandez; Kyle, Robert A.; Durie, Brian GM; Ludwig, Heinz; Usmani, Saad; Vesole, David H.; Hajek, Roman; Miguel, Jesus San; Sezer, Orhan; Sonneveld, Pieter; Kumar, Shaji K.; Mahindra, Anuj; Comenzo, Ray; Palumbo, Antonio; Mazumber, Amitabha; Anderson, Kenneth C.; Richardson, Paul G.; Badros, Ashraf Z.; Caers, Jo; Cavo, Michele; LeLeu, Xavier; Dimopoulos, Meletios A.; Chim, CS; Schots, Rik; Noeul, Amara; Fantl, Dorotea; Mellqvist, Ulf-Henrik; Landgren, Ola; Chanan-Khan, Asher; Moreau, Philippe; Fonseca, Rafael; Merlini, Giampaolo; Lahuerta, JJ; Blade, Joan; Orlowski, Robert Z.; Shah, Jatin J.

2014-01-01

259

A nanoparticle in plasma  

SciTech Connect

Charge and energy fluxes onto a nanoparticle under conditions typical of laboratory plasmas are investigated theoretically. Here, by a nanoparticle is meant a grain the size of which is much smaller than both the electron Larmor radius and Debye length and the thermionic emission from which is not limited by the space charge. Under conditions at which thermionic emission plays an important role, the electric potential and temperature T{sub p} of a nanoparticle are determined by solving a self-consistent set of equations describing the balance of energy and charge fluxes onto the nanoparticle. It is shown that, when the degree of plasma ionization exceeds a critical level, the potential of the nanoparticle and the energy flux onto it increase with increasing nanoparticle temperature, so that, starting from a certain temperature, the nanoparticle potential becomes positive. The critical degree of ionization starting from which the potential of a nanoparticle is always positive is determined as a function of the plasma density and electron temperature. The nanoparticle temperature T{sub p} corresponding to the equilibrium state of a positively charged nanoparticle is found as a function of the electron density for different electron temperatures.

Martynenko, Yu. V.; Nagel', M. Yu.; Orlov, M. A. [Russian Research Centre Kurchatov Institute (Russian Federation)

2009-06-15

260

Sluggish response of untrapped electrons and global electrostatic micro-instabilities in a tokamak  

NASA Astrophysics Data System (ADS)

Electrons whether adiabatic or non-adiabatic play important role in determining the stability properties of a global electrostatic mode. In the present analysis, the effect of non-adiabaticity of electrons with all its kinetic effects is investigated for ion temperature gradient driven mode in the presence of fast ions using a linear gyro-kinetic code EM-GLOGYSTO-F.

Chowdhury, J.; Ganesh, R.; Angelino, P.; Vaclavik, J.; Villard, L.; Brunner, S.

2010-02-01

261

PPPL3243 Preprint: March 1997, UC427 Microinstability Properties of Negative Magnetic Shear Discharges in the  

E-print Network

frequency resonances and of ion temperature gradients. The theoretical tool employed here. A comprehensive kinetic lin- ear eigenmode calculation employing the ballooning representation is employed profiles (density, temperature, , rotation, etc.) on the linear growth rates is consid- ered. 52.55Fa, 52

262

Collisionless microinstabilities in stellarators. III. The ion-temperature-gradient mode  

NASA Astrophysics Data System (ADS)

We investigate the linear theory of the ion-temperature-gradient (ITG) mode, with the goal of developing a general understanding that may be applied to stellarators. We highlight the Wendelstein 7X (W7-X) device. Simple fluid and kinetic models that follow closely from existing literature are reviewed and two new first-principle models are presented and compared with results from direct numerical simulation. One model investigates the effect of regions of strong localized shear, which are generic to stellarator equilibria. These "shear spikes" are found to have a potentially significant stabilizing affect on the mode; however, the effect is strongest at short wavelengths perpendicular to the magnetic field, and it is found to be significant only for the fastest growing modes in W7-X. A second model investigates the long-wavelength limit for the case of negligible global magnetic shear. The analytic calculation reveals that the effect of the curvature drive enters at second order in the drift frequency, confirming conventional wisdom that the ITG mode is slab-like at long wavelengths. Using flux tube simulations of a zero-shear W7-X configuration, we observe a close relationship to an axisymmetric configuration at a similar parameter point. It is concluded that scale lengths of the equilibrium gradients constitute a good parameter space to characterize the ITG mode. Thus, to optimize the magnetic geometry for ITG mode stability, it may be fruitful to focus on local parameters, such as the magnitude of bad curvature, connection length, and local shear at locations of bad curvature (where the ITG mode amplitude peaks).

Plunk, G. G.; Helander, P.; Xanthopoulos, P.; Connor, J. W.

2014-03-01

263

Microinstabilities and the production of short-wavelength irregularities in the auroral F region  

Microsoft Academic Search

The action of ion-neutral charge exchange collisions and the large E x B drifts that can exist in the auroral ionospheric F region lead to an ion velocity distribution which is anisotropic and can be peaked at finite v. Such distributions are unstable to the Post-Rosenbluth instability if the relative ion-neutral drift velocity exceeds 1.8 times the neutral thl:rmal velocity.

Edward Ott

1975-01-01

264

Plasma immersion surface modification with metal ion plasma  

SciTech Connect

We describe here a novel technique for surface modification in which metal plasma is employed and by which various blends of plasma deposition and ion implantation can be obtained. The new technique is a variation of the plasma immersion technique described by Conrad and co-workers. When a substrate is immersed in a metal plasma, the plasma that condenses on the substrate remains there as a film, and when the substrate is then implanted, qualitatively different processes can follow, including' conventional' high energy ion implantation, recoil implantation, ion beam mixing, ion beam assisted deposition, and metallic thin film and multilayer fabrication with or without species mixing. Multiple metal plasma guns can be used with different metal ion species, films can be bonded to the substrate through ion beam mixing at the interface, and multilayer structures can be tailored with graded or abrupt interfaces. We have fabricated several different kinds of modified surface layers in this way. 22 refs., 4 figs.

Brown, I.G.; Yu, K.M. (Lawrence Berkeley Lab., CA (USA)); Godechot, X. (Lawrence Berkeley Lab., CA (USA) Societe Anonyme d'Etudes et Realisations Nucleaires (SODERN), 94 - Limeil-Brevannes (France))

1991-04-01

265

Systematic study of plasma flow during plasma sheet thinnings  

NASA Technical Reports Server (NTRS)

On the basis of a study of Imp 6 measurements of plasma flow, it is concluded that there is no clear indication of a predominance of tailward plasma flow beyond about X = -15 R sub E in the midnight sector of the plasma sheet during the expansive phase of a substorm. In fact, it is shown statistically that sunward plasma flow is more frequently observed in the midnight sector within about 30 R sub E from the earth than in any other direction during plasma sheet thinning at the substorm expansion. This result supports the conclusion that there is no definite evidence for the formation of a reconnection neutral line in the near-earth plasma sheet during most substorms.

Lui, A. T. Y.; Frank, L. A.; Ackerson, K. L.; Meng, C.-I.; Akasofu, S.-I.

1977-01-01

266

Plasma generating apparatus for large area plasma processing  

DOEpatents

A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm.sup.2. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity.

Tsai, Chin-Chi (Oak Ridge, TN); Gorbatkin, Steven M. (Oak Ridge, TN); Berry, Lee A. (Oak Ridge, TN)

1991-01-01

267

Plasma generating apparatus for large area plasma processing  

DOEpatents

A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm[sup 2]. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity. 3 figures.

Tsai, C.C.; Gorbatkin, S.M.; Berry, L.A.

1991-07-16

268

Plasma surface cleaning in a microwave plasma source  

SciTech Connect

A microwave electron cyclotron resonance (ECR) plasma source has been operated to produce reactive plasmas of oxygen and its mixture with argon. Aluminum samples (0.95 cm by 1.9 cm) were coated with thin films (<20 {mu}m in thickness) of Shell Vitrea oil and cleaned by using such reactive plasmas. The plasma cleaning was done in discharge conditions of microwave power up to 1300 W, radio frequency power up to 200 W, biased potential up to 400 V, gas pressures up to 5 mtorr, and operating time up to 35 min. The surface texture of the postcleaned samples has been examined visually. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured clean rates of low-pressure (0.5-mtorr) argon/oxygen plasmas were as high as 2.7 {mu}m/min. X-ray photoelectron spectroscopy (XPS) was used to determine cleanliness of the sample surfaces after plasma cleaning. The XPS study on polished samples confirmed the effectiveness of plasma cleaning in achieving atomic level of surface cleanliness. In this technical memorandum plasma properties, cleaning phenomena, and significant results are reported and discussed.

Tsai, C.C.; Nelson, W.D.; Haselton, H.H.; Schechter, D.E. [Oak Ridge National Lab., TN (United States); Thompson, L.M.; Campbell, V.B.; Glover, A.L.; Googin, J.M. [Oak Ridge Y-12 Plant, TN (United States)

1994-03-01

269

Towards Plasma Surgery: Plasma Treatment of Living Cells  

SciTech Connect

The physical, biological and technical background for high-precision plasma surgery is prepared in a multi-disciplinary team. The aim of the research is to achieve controlled removal of diseased cells and bacteria without harming the healthy rest of the tissue. For this purpose, a small, cold, flexible and non-toxic plasma is developed (the plasma needle) and tested on cultured cells and bacterial samples. The needle is an atmospheric discharge induced by a radio-frequency voltage applied to a metal pin. This plasma operates at room temperature, in the milliwatt power regime; it poses no risk of thermal or electrical damage to living tissues. Several beneficial responses of living cells to plasma treatment have been already identified. Plasma does not cause accidental cell death (necrosis), which leads to inflammation and tissue damage. Instead, it allows to detach cells from each other and from the scaffold, and thus to remove them in a non-destructive way. Moreover, plasma is capable of bacterial inactivation. I parallel, we have determined the electrical and optical properties of the plasma and found a method of precise positioning of the plasma needle with respect to the treated tissue.

Stoffels, E.; Kieft, I.E.; Sladek, R.E.J.; Slaaf, D.W.; Laan, E.P. van der; Jimenez-Moreno, P.; Steinbuch, M. [Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven (Netherlands); Department of Mechanical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven (Netherlands)

2004-12-01

270

Surface plasma wave excitation via laser irradiated overdense plasma foil  

SciTech Connect

A laser irradiated overdense plasma foil is seen to be susceptible to parametric excitation of surface plasma wave (SPW) and ion acoustic wave (IAW) on the ion plasma period time scale. The SPW is localised near the front surface of the foil while IAW extends upto the rear. The evanescent laser field and the SPW exert a ponderomotive force on electrons driving the IAW. The density perturbation associated with the latter beats with the laser induced oscillatory electron velocity to drive the SPW. At relativistic laser intensity, the growth rate is of the order of ion plasma frequency.

Kumar, Pawan; Tripathi, V. K. [Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India)

2012-04-09

271

Resonance microwave volume plasma source  

SciTech Connect

A conceptual design of a microwave gas-discharge plasma source is described. The possibility is considered of creating conditions under which microwave energy in the plasma resonance region would be efficiently converted into the energy of thermal and accelerated (fast) electrons. Results are presented from interferometric and probe measurements of the plasma density in a coaxial microwave plasmatron, as well as the data from probe measurements of the plasma potential and electron temperature. The dynamics of plasma radiation was recorded using a streak camera and a collimated photomultiplier. The experimental results indicate that, at relatively low pressures of the working gas, the nonlinear interaction between the microwave field and the inhomogeneous plasma in the resonance region of the plasmatron substantially affects the parameters of the ionized gas in the reactor volume.

Berezhetskaya, N. K.; Kop'ev, V. A.; Kossyi, I. A.; Malykh, N. I.; Misakyan, M. A.; Taktakishvili, M. I.; Temchin, S. M. [Russian Academy of Sciences, Prokhorov Institute of General Physics (Russian Federation); Lee, Young Dong [Samsung Advanced Institute of Technology (Korea, Republic of)

2007-07-15

272

Plasma Detachment Study in VASIMR  

NASA Astrophysics Data System (ADS)

We present kinetic and MHD simulations of plasma detachment in the exhaust of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR). The detachment is associated with a transition from subalfvenic to superalfvenic plasma flow in the magnetic nozzle. As a result, the kinetic energy of the outgoing plasma flow is greater than the magnetic field energy in the exhaust area, so that the plasma is no longer confined by the magnetic field. We model the outgoing plasma flow under the assumptions that the plasma is collisionless and has a constant electron temperature. Particle simulations show that the ion motion may become nonadiabatic in the exhaust area as the magnetic field decreases downstream. This effect should facilitate the detachment.

Ilin, A. V.; Díaz, F. R. Chang; Squire, J. P.; Breizman, B. N.; Novakovski, S. V.; Sagdeev, R. Z.

2000-10-01

273

Characterizing plasma mirrors near breakdown  

SciTech Connect

Experiments dedicated to the characterization of plasma mirrors with a high energy, single shot short-pulse laser were performed at the 100 TW target area of the Z-Backlighter Facility at Sandia National Laboratories. A suite of beam diagnostics was used to characterize a high energy laser pulse with a large aperture through focus imaging setup. By varying the fluence on the plasma mirror around the plasma ignition threshold, critical performance parameters were determined and a more detailed understanding of the way in which a plasma mirror works could be deduced. It was found, that very subtle variations in the laser near field profile will have strong effects on the reflected pulse if the maximum fluence on the plasma mirror approaches the plasma ignition threshold.

Geissel, Matthias; Schollmeier, Marius S.; Kimmel, Mark W.; Rambo, Patrick K.; Schwarz, Jens; Atherton, Briggs W. [Sandia National Laboratories, Z-Backlighter Facility, Albuquerque, New Mexico 87185-1193 (United States); Brambrink, Erik [Ecole Polytechnique, Laboratoire d'Utilisation des Lasers Intenses, Palaiseau (France)

2011-05-15

274

Plasma Chemistry and Plasma Processing, Vol. 12, No.4, 1992 Infrared Radiation from an Arc Plasma and Its  

E-print Network

B ) Plasma Chemistry and Plasma Processing, Vol. 12, No.4, 1992 Infrared Radiation from an Arc Plasma and Its Application to Plasma Diagnostics Takayoshi Ohji1 and Thomas W. Eagar Received May 16 ifinfraredradiation from an arc plasma can fie used for diagnostic purposes. Tire properties of IR radiation

Eagar, Thomas W.

275

Strongly magnetized classical plasma models  

NASA Technical Reports Server (NTRS)

Discrete particle processes in the presence of a strong external magnetic field were investigated. These processes include equations of state and other equilibrium thermodynamic relations, thermal relaxation phenomena, transport properties, and microscopic statistical fluctuations in such quantities as the electric field and the charge density. Results from the equilibrium statistical mechanics of two-dimensional plasmas are discussed, along with nonequilibrium statistical mechanics of the electrostatic guiding-center plasma (a two-dimensional plasma model).

Montgomery, D.; Peyraud, J.; Dewitt, C.

1974-01-01

276

Magnetic insulation for plasma propulsion  

NASA Technical Reports Server (NTRS)

The design parameters of effective magnetic insulation for plasma engines are discussed. An experimental model used to demonstrate the process of plasma acceleration and magnetic insulation is considered which consists of a copper strap that is wound around a glass tube and connected to a capacitor. In order to adequately model the magnetic insulation mechanisms, a computer algorithm is developed. Plasma engines, with their efficient utilization of the propellant mass, are expected to provide the next-generation advanced propulsion systems.

Gonzalez, Dora E.

1990-01-01

277

Plasma patterning of carbon nanotubes  

Microsoft Academic Search

We have prepared micropatterns of carbon nanotubes on a wide range of substrates either by patterned growth of aligned nanotubes on surfaces prepatterned with plasma polymers (e.g., n-hexane plasma polymer) or through region-specific adsorption of certain chemically modified carbon nanotubes (e.g., -COOH substituted nanotubes) onto surfaces prepatterned with various plasma-generated functionalities (e.g., -NH2). Micropatterns of carbon nanotubes prepared in both

Qidao Chen; Liming Dai

2000-01-01

278

Plasma Sail Concept Fundamentals  

NASA Technical Reports Server (NTRS)

The mini-magnetospheric plasma propulsion (M2P2) device, originally proposed by Winglee et al., predicts that a 15-km standoff distance (or 20-km cross-sectional dimension) of the magnetic bubble will provide for sufficient momentum transfer from the solar wind to accelerate a spacecraft to unprecedented speeds of 50 C80 km/s after an acceleration period of 3 mo. Such velocities will enable travel out of the solar system in period of 7 yr almost an order of magnitude improvement over present chemical-based propulsion systems. However, for the parameters of the simulation of Winglee et al., a fluid model for the interaction of M2P2 with the solar wind is not valid. It is assumed in the magnetohydrodynamic (MHD) fluid model, normally applied to planetary magnetospheres, that the characteristic scale size is much greater than the Larmor radius and ion skin depth of the solar wind. In the case of M2P2, the size of the magnetic bubble is actually less than or comparable to the scale of these characteristic parameters. Therefore, a kinetic approach, which addresses the small-scale physical mechanisms, must be used. A two-component approach to determining a preliminary estimate of the momentum transfer to the plasma sail has been adopted. The first component is a self-consistent MHD simulation of the small-scale expansion phase of the magnetic bubble. The fluid treatment is valid to roughly 5 km from the source and the steady-state MHD solution at the 5 km boundary was then used as initial conditions for the hybrid simulation. The hybrid simulations showed that the forces delivered to the innermost regions of the plasma sail are considerably ( 10 times) smaller than the MHD counterpart, are dominated by the magnetic field pressure gradient, and are directed primarily in the transverse direction.

Khazanov, G. V.; Delamere, P.; Kabin, K.; Linde, T. J.

2004-01-01

279

Compact Plasma Accelerator  

NASA Technical Reports Server (NTRS)

A plasma accelerator has been conceived for both material-processing and spacecraft-propulsion applications. This accelerator generates and accelerates ions within a very small volume. Because of its compactness, this accelerator could be nearly ideal for primary or station-keeping propulsion for spacecraft having masses between 1 and 20 kg. Because this accelerator is designed to generate beams of ions having energies between 50 and 200 eV, it could also be used for surface modification or activation of thin films.

Foster, John E.

2004-01-01

280

Human Plasma Membrane Receptome  

NSDL National Science Digital Library

Cell receptor researchers have an excellent online resource in the Human Plasma Membrane Receptome (HPMR) database from the Aaron Hsueh lab, part of the Division of Reproductive Biology at Stanford University Medical Center. The database contains information for over 1000 individual cell receptors and offers a number of search options. For instance, users can navigate a concept map diagram organized by receptor function or browse a phylogenetic tree with receptor families organized by evolutionary relationship. The database provides detailed information for each receptor, including PubMed citations.

281

Pulsed Plasma Thruster Technology  

NASA Technical Reports Server (NTRS)

The continuing emphasis on reducing costs and downsizing spacecraft is forcing increased emphasis on reducing the subsystem mass and integration costs. For many commercial, scientific, and Department of Defense space missions, onboard propulsion is either the predominant spacecraft mass or it limits the spacecraft lifetime. Electromagnetic-pulsed-plasma thrusters (PPT's) offer the combined benefits of extremely low average electric power requirements (1 to 150 W), high specific impulse (approx. 1000 sec), and system simplicity derived from the use of an inert solid propellant. Potential applications range from orbit insertion and maintenance of small satellites to attitude control for large geostationary communications satellites.

1996-01-01

282

Modeling of Photoionized Plasmas  

NASA Technical Reports Server (NTRS)

In this paper I review the motivation and current status of modeling of plasmas exposed to strong radiation fields, as it applies to the study of cosmic X-ray sources. This includes some of the astrophysical issues which can be addressed, the ingredients for the models, the current computational tools, the limitations imposed by currently available atomic data, and the validity of some of the standard assumptions. I will also discuss ideas for the future: challenges associated with future missions, opportunities presented by improved computers, and goals for atomic data collection.

Kallman, Timothy R.

2010-01-01

283

Particle simulations in magnetospheric plasmas  

NASA Technical Reports Server (NTRS)

In view of the recent remarkable advancement of computer technology and simulation software, simulation studies are one of the most powerful academic tools for establishment of quantitative space physics and modelling of our space environment. The complex nature encountered in space plasma physics has motivated considerable development in computer simulations, which have played an essential role in the development of space plasma theory. This report describes research undertaken to understand physical processes involved in plasma waves observed in the magnetospheric plasmas, and associated nonlinear phenomena such as heating, diffusion, and acceleration of particles due to excited waves. The research explains and clarifies the observational data both qualitatively and quantitatively.

Nishikawa, Ken-Ichi

1990-01-01

284

Ternary gas plasma welding torch  

NASA Technical Reports Server (NTRS)

A plasma arc welding torch is discussed. A first plasma gas is directed through the body of the welding torch and out of the body across the tip of a welding electrode disposed at the forward end of the body. A second plasma gas is disposed for flow through a longitudinal bore in the electrode. The second plasma gas enters one end of the electrode and exits the electrode at the tip thereof for co-acting with the electric welding arc to produce the desired weld. A shield gas is directed through the torch body and circulates around the head of the torch adjacent to the electrode tip.

Rybicki, Daniel J. (inventor); Mcgee, William F. (inventor); Waldron, Douglas J. (inventor)

1995-01-01

285

Vacuum Plasma Spraying Replaces Electrodeposition  

NASA Technical Reports Server (NTRS)

Vacuum plasma spraying used to fabricate large parts with complicated contours and inner structures, without uninspectable welds. Reduces time, and expense of fabrication. Wall of combustion chamber built up inside of outer nickel-alloy jacket by plasma spraying. Particles of metal sprayed partially melted in plasma gun and thrown at supersonic speed toward deposition surface. Vacuum plasma-spray produces stronger bond between the grooves and covering layer completing channels and wall of combustion chamber. In tests, bond withstood pressure of 20 kpsi, three times allowable limit by old method.

Holmes, Richard R.; Power, Chris; Burns, David H.; Daniel, Ron; Mckechnie, Timothy N.

1992-01-01

286

Autoresonant Excitation of Antiproton Plasmas  

SciTech Connect

We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination.

Andresen, G. B.; Bowe, P. D.; Hangst, J. S. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Ashkezari, M. D.; Hayden, M. E. [Department of Physics, Simon Fraser University, Burnaby British Columbia, V5A 1S6 (Canada); Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Madsen, N.; Werf, D. P. van der [Department of Physics, Swansea University, Swansea SA2 8PP (United Kingdom); Carpenter, P. T.; Hurt, J. L.; Robicheaux, F. [Department of Physics, Auburn University, Auburn, Alabama 36849-5311 (United States); Cesar, C. L. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil)

2011-01-14

287

Plasma contacting - An enabling technology  

NASA Technical Reports Server (NTRS)

An experimental study of plasma contacting with an emphasis on the electron collection mode of this process is described. Results illustrating variations in plasma property profiles and potential differences that develop at hollow cathode plasma contactors are presented. A model of the electron collection plasma contacting process that is consistent with experimentally measured results is reviewed. The shortcomings of laboratory results as direct predictors of contactor performance in space and their usefulness in validating numerical models of the contacting process, that can be used to predict such performance, are discussed.

Williams, John D.; Wilbur, Paul J.

1989-01-01

288

Ion acceleration in laboratory plasmas  

NASA Technical Reports Server (NTRS)

Recent experiments which investigate ion acceleration in 'collisionless' laboratory plasmas are described. The experiments fall into two classes - those involving stationary and those involving time dependent processes.Among the stationary structures which accelerate ions are sheaths, presheaths, double layers, multiple double layers and ambipolar potentials. RF is an example of time dependent processes. Both classes of experiments are considered. Experiments with 'collisionless' plasmas in multidipole triple plasma-type devices and novel phenomena associated with the use of Ion Cyclotron Resonance Heating in the inhomogeneous magnetic field of a tandem mirror 'fusion' plasma are described. New RF phenomenon include RF pitch angle scattering, RF electron pumping, and ICRF ponderomotive force.

Hershkowitz, Noah

1986-01-01

289

Method for generating surface plasma  

DOEpatents

A method for generating a discharge plasma which covers a surface of a body in a gas at pressures from 0.01 Torr to atmospheric pressure, by applying a radio frequency power with frequencies between approximately 1 MHz and 10 GHz across a plurality of paired insulated conductors on the surface. At these frequencies, an arc-less, non-filamentary plasma can be generated to affect the drag characteristics of vehicles moving through the gas. The plasma can also be used as a source in plasma reactors for chemical reaction operations.

Miller, Paul A. (Albuquerque, NM); Aragon, Ben P. (Albuquerque, NM)

2003-05-27

290

On the excess energy of nonequilibrium plasma  

SciTech Connect

The energy that can be released in plasma due to the onset of instability (the excess plasma energy) is estimated. Three potentially unstable plasma states are considered, namely, plasma with an anisotropic Maxwellian velocity distribution of plasma particles, plasma with a two-beam velocity distribution, and an inhomogeneous plasma in a magnetic field with a local Maxwellian velocity distribution. The excess energy can serve as a measure of the degree to which plasma is nonequilibrium. In particular, this quantity can be used to compare plasmas in different nonequilibrium states.

Timofeev, A. V. [National Research Centre Kurchatov Institute, Institute of Hydrogen Power Engineering and Plasma Technologies (Russian Federation)

2012-01-15

291

Tool kit for space plasma physics  

E-print Network

2 Tool kit for space plasma physics Most of the Universe is made of plasma. And yet, plasmas kit for space plasma physics Figure 2.1 Solids, liquids and gases abound on the Earth, but most plasma physics: non-Maxwellian distributions, which are ubiquitous in the heliosphere ­ fooling our

Demoulin, Pascal

292

Multidimensional Plasma Sheaths over Electrically Inhomogeneous Surfaces  

Microsoft Academic Search

Multidimensional plasma sheaths are encountered in a number of applications including plasma immersion ion implantation, extraction of ions (or plasma) through grids, MEMS fabrication, neutral beam sources, and plasma in contact with internal reactor parts (e.g., wafer chuck edge). The sheath may be multidimensional when: (a) plasma is in contact with surface topography, and the size of the topographical features

Demetre Economou

2004-01-01

293

Probe measurements in thermal plasma jets  

Microsoft Academic Search

Measurements of composition, temperature, and velocity in atmospheric argon plasma jets are reported, using enthalpy probes. The plasma jets are generated by a commercial type plasma gun and the measurements are expected to be of particular interest for industrial applications such as plasma spraying. Emphasis has been on the central and downstream regions of the plasma flame. The entrainment of

M. Brossa; E. Pfender

1988-01-01

294

Plasma, The Fourth State of Matter  

ERIC Educational Resources Information Center

Discusses plasma as a source of energy through nuclear fission processes, as well as the difficulties encountered in such a process. States that 99 percent of the matter in the universe is plasma, and only 1 percent is the common three states of matter. Describes the fundamental properties of plasma, plasma "pinch, and plasma oscillations. (RR)

Zandy, Hassan F.

1970-01-01

295

Nonequilibrium effects in supersonic induction plasma  

Microsoft Academic Search

Supersonic plasma jets find applications in plasma chemistry and plasma processing, metallurgy, experimental physics, and space technology. Usually the plasma in these jets deviates from chemical and thermal equilibrium. To optimize the industrial process detailed study of nonequilibrium effects in supersonic flow is required. In the article we apply numerical simulation to study the supersonically accelerated argon plasma flow downstream

S. E. Selezneva; M. I. Boulos

2002-01-01

296

Plasma Treatment for Improved Bonding: A Review  

Microsoft Academic Search

The nature of low-pressure glow-discharge plasma, plasma equipment, and the effect of plasma on materials is reviewed. Examples are given of the improved adhesive bonding of polymers after plasma treatment (2–10 times improvement in lap-shear) and of the surface cleaning and chemical modification that occurs during plasma treatment.

Edward M. Liston

1989-01-01

297

Purification of tantalum by plasma arc melting  

DOEpatents

Purification of tantalum by plasma arc melting. The level of oxygen and carbon impurities in tantalum was reduced by plasma arc melting the tantalum using a flowing plasma gas generated from a gas mixture of helium and hydrogen. The flowing plasma gases of the present invention were found to be superior to other known flowing plasma gases used for this purpose.

Dunn, Paul S. (Santa Fe, NM); Korzekwa, Deniece R. (Los Alamos, NM)

1999-01-01

298

PLASMA AS A PROPELLANT FOR SPACE TRAVEL  

Microsoft Academic Search

Chemical rocket motors have limited possibilities for space travel ; problems. Ionic and plasma motors are promising in this regard. The working ; principle of the plasma motor depends on the acceleration of the plasma in ; electric and magnetic fields as well as possible contraction of the plasma ; radiation. From the numerous kinds of plasma motors, the magnetohydrodynamic

1961-01-01

299

Burning Plasma Science Workshop Astrophysics and Laboratory Plasmas  

E-print Network

cosmic rays ¥ Galactic cosmic rays ¥ Ultra-relativistic cosmic rays ¥ Nuclear processes ¥ Synthesis-detonation transition ¥ Radiation hydrodynamics/instabilities ¥ Filamentation ¥ Plasma acceleration #12;Burning Plasma ¥ At least 3 components ¥ Galactic (and solar) cosmic rays (CR) ¥ Extragalactic cosmic rays ¥ Ultra

300

Destruction de Dechets par Plasma (Waste Destruction by Plasma).  

National Technical Information Service (NTIS)

The utilization of high power plasma torches to destroy dangerous industrial wastes is discussed. The operational status of plasma torches of up to 10 MW power allows its application to treat chemical waste at temperatures of up to 10,000 C, to make sure ...

M. D. Pineau

1988-01-01

301

Electrostatic Plasma Accelerator (EPA)  

NASA Technical Reports Server (NTRS)

The application of electric propulsion to communications satellites, however, has been limited to the use of hydrazine thrusters with electric heaters for thrust and specific impulse augmentation. These electrothermal thrusters operate at specific impulse levels of approximately 300 s with heater powers of about 500 W. Low power arcjets (1-3 kW) are currently being investigated as a way to increase specific impulse levels to approximately 500 s. Ion propulsion systems can easily produce specific impulses of 3000 s or greater, but have yet to be applied to communications satellites. The reasons most often given for not using ion propulsion systems are their high level of overall complexity, low thrust with long burn times, and the difficulty of integrating the propulsion system into existing commercial spacecraft busses. The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass.

Brophy, John R.; Aston, Graeme

1995-01-01

302

Periodically oscillating plasma sphere  

SciTech Connect

The periodically oscillating plasma sphere, or POPS, is a novel fusion concept first proposed by D. C. Barnes and R. A. Nebel [Fusion Technol. 38, 28 (1998)]. POPS utilizes the self-similar collapse of an oscillating ion cloud in a spherical harmonic oscillator potential well formed by electron injection. Once the ions have been phase-locked, their coherent motion simultaneously produces very high densities and temperatures during the collapse phase of the oscillation. A requirement for POPS is that the electron injection produces a stable harmonic oscillator potential. This has been demonstrated in a gridded inertial electrostatic confinement device and verified by particle simulation. Also, the POPS oscillation has been confirmed experimentally through observation that the ions in the potential well exhibit resonance behavior when driven at the POPS frequency. Excellent agreement between the observed POPS frequencies and the theoretical predictions has been observed for a wide range of potential well depths and three different ion species. Practical applications of POPS require large plasma compressions. These large compressions have been observed in particle simulations, although space charge neutralization remains a major issue.

Park, J.; Nebel, R.A.; Stange, S.; Murali, S. Krupakar [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); University of Wisconsin, Madison, Wisconsin 53706 (United States)

2005-05-15

303

Periodically oscillating plasma spherea)  

NASA Astrophysics Data System (ADS)

The periodically oscillating plasma sphere, or POPS, is a novel fusion concept first proposed by D. C. Barnes and R. A. Nebel [Fusion Technol. 38, 28 (1998)]. POPS utilizes the self-similar collapse of an oscillating ion cloud in a spherical harmonic oscillator potential well formed by electron injection. Once the ions have been phase-locked, their coherent motion simultaneously produces very high densities and temperatures during the collapse phase of the oscillation. A requirement for POPS is that the electron injection produces a stable harmonic oscillator potential. This has been demonstrated in a gridded inertial electrostatic confinement device and verified by particle simulation. Also, the POPS oscillation has been confirmed experimentally through observation that the ions in the potential well exhibit resonance behavior when driven at the POPS frequency. Excellent agreement between the observed POPS frequencies and the theoretical predictions has been observed for a wide range of potential well depths and three different ion species. Practical applications of POPS require large plasma compressions. These large compressions have been observed in particle simulations, although space charge neutralization remains a major issue.

Park, J.; Nebel, R. A.; Stange, S.; Murali, S. Krupakar

2005-05-01

304

Undamped electrostatic plasma waves  

SciTech Connect

Electrostatic waves in a collision-free unmagnetized plasma of electrons with fixed ions are investigated for electron equilibrium velocity distribution functions that deviate slightly from Maxwellian. Of interest are undamped waves that are the small amplitude limit of nonlinear excitations, such as electron acoustic waves (EAWs). A deviation consisting of a small plateau, a region with zero velocity derivative over a width that is a very small fraction of the electron thermal speed, is shown to give rise to new undamped modes, which here are named corner modes. The presence of the plateau turns off Landau damping and allows oscillations with phase speeds within the plateau. These undamped waves are obtained in a wide region of the (k,{omega}{sub R}) plane ({omega}{sub R} being the real part of the wave frequency and k the wavenumber), away from the well-known 'thumb curve' for Langmuir waves and EAWs based on the Maxwellian. Results of nonlinear Vlasov-Poisson simulations that corroborate the existence of these modes are described. It is also shown that deviations caused by fattening the tail of the distribution shift roots off of the thumb curve toward lower k-values and chopping the tail shifts them toward higher k-values. In addition, a rule of thumb is obtained for assessing how the existence of a plateau shifts roots off of the thumb curve. Suggestions are made for interpreting experimental observations of electrostatic waves, such as recent ones in nonneutral plasmas.

Valentini, F.; Perrone, D.; Veltri, P. [Dipartimento di Fisica and CNISM, Universita della Calabria, 87036 Rende (CS) (Italy); Califano, F.; Pegoraro, F. [Dipartimento di Fisica and CNISM, Universita di Pisa, 56127 Pisa (Italy); Morrison, P. J. [Institute for Fusion Studies and Department of Physics, University of Texas at Austin, Austin, Texas 78712-1060 (United States); O'Neil, T. M. [Department of Physics, University of California at San Diego, La Jolla, California 92093 (United States)

2012-09-15

305

Criticality in Plasma Membranes  

NASA Astrophysics Data System (ADS)

We are motivated by recent observations of micron-sized critical fluctuations in the 2d Ising Universality class in plasma membrane vesicles that are isolated from cortical cytoskeleton. We construct a minimal model of the plasma membrane's interaction with intact cytoskeleton which explains why large scale phase separation has not been observed in Vivo. In addition, we use analytical techniques from conformal field theory and numerical simulations to investigate the form of effective forces mediated by the membrane's proximity to criticality. We show that the range of this force is maximized near a critical point and we quantify its usefulness in mediating communication using techniques from information theory. Finally we use theoretical techniques from statistical physics in conjunction with Monte-Carlo simulations to understand how criticality can be used to increase the efficiency of membrane bound receptor mediated signaling. We expect that this sort of analysis will be broadly useful in understanding and quantifying the role of lipid "rafts" in a wide variety of membrane bound processes. Generally, we demonstrate that critical fluctuations provide a physical mechanism to organize and spatially segregate membrane components by providing channels for interaction over relatively large distances.

Machta, Benjamin; Papanikolaou, Stefanos; Sethna, James; Veatch, Sarah

2011-03-01

306

Plasma motor generator system  

NASA Technical Reports Server (NTRS)

The significant potential advantages of a plasma motor generator system over conventional systems for the generation of electrical power and propulsion for spacecraft in low Earth orbits warrants its further investigation. The two main components of such a system are a long insulated wire and the plasma generating hollow cathodes needed to maintain electrical contact with the ionosphere. Results of preliminary theoretical and experimental investigations of this system are presented. The theoretical work involved the equilibrium configurations of the wire and the nature of small oscillation about these equilibrium positions. A particularly interesting result was that two different configurations are allowed when the current is above a critical value. Experimental investigations were made of the optimal starting and running conditions for the proposed, low current hollow cathodes. Although optimal ranges of temperature, argon pressure and discharge voltage were identified, start up became progressively more difficult. This supposed depletion or contamination of the emissive surface could be countered by the addition of new emissive material.

Hite, Gerald E.

1987-01-01

307

Pulsed Plasma Thruster Contamination  

NASA Technical Reports Server (NTRS)

Pulsed Plasma Thrusters (PPT's) are currently baselined for the Air Force Mightysat II.1 flight in 1999 and are under consideration for a number of other missions for primary propulsion, precision positioning, and attitude control functions. In this work, PPT plumes were characterized to assess their contamination characteristics. Diagnostics included planar and cylindrical Langmuir probes and a large number of collimated quartz contamination sensors. Measurements were made using a LES 8/9 flight PPT at 0.24, 0.39, 0.55, and 1.2 m from the thruster, as well as in the backflow region behind the thruster. Plasma measurements revealed a peak centerline ion density and velocity of approx. 6 x 10(exp 12) cm(exp -3) and 42,000 m/s, respectively. Optical transmittance measurements of the quartz sensors after 2 x 10(exp 5) pulses showed a rapid decrease in plume contamination with increasing angle from the plume axis, with a barely measurable transmittance decrease in the ultraviolet at 90 deg. No change in optical properties was detected for sensors in the backflow region.

Myers, Roger M.; Arrington, Lynn A.; Pencil, Eric J.; Carter, Justin; Heminger, Jason; Gatsonis, Nicolas

1996-01-01

308

Plasma-based accelerating structures  

NASA Astrophysics Data System (ADS)

Plasma-based accelerators have the ability to sustain extremely large accelerating gradients, with possible high-energy physics applications. This dissertation further develops the theory of plasma-based accelerators by addressing three topics: the performance of a hollow plasma channel as an accelerating structure, the generation of ultrashort electron bunches, and the propagation of laser pulses in underdense plasmas. The excitation of plasma waves in a hollow plasma channel by a laser pulse or relativistic charged particle beam is analyzed. The mode frequencies and loss factors of the excited channel modes are calculated. The effects of non- ideal hollow plasma channels are discussed. Particle beam stability in a hollow plasma channel is examined. The dipole wakefield couples to the transverse displacement of the particle beam, which results in beam breakup. Single-bunch beam breakup growth lengths are derived for particle beam propagation in the weak-focusing and strong-focusing regimes. The effects of longitudinal wakefields on the beam energy spread is examined. Multi- bunch beam breakup is discussed and methods for reducing beam breakup are proposed and evaluated. The production of ultrashort electron bunches by dephasing and trapping background plasma electrons undergoing fluid oscillations in a plasma wave is studied. The plasma electrons are dephased by colliding two counter-propagating laser pulses which generate a slow phase velocity beat wave. The threshold laser pulse amplitudes, the optimal injection phase for trapping, and the trapping volume are calculated. The dynamics and quality of the generated electron bunches are examined. The analysis indicates that this optical injection scheme has the capability to produce relativistic femtosecond electron bunches with fractional energy spread of a few percent and normalized transverse emittance less than 1 mm mrad using 1 terawatt injection laser pulses. The propagation of ultrashort high-power laser pulses in underdense plasmas is studied. Envelope equations are derived for optical beam parameters which include finite- radius and finite pulse length effects. Solutions of the envelope equations are presented for an adiabatic plasma response. For the general non-adiabatic plasma response, laser-plasma instabilities are examined and asymptotic instability growth rates are derived.

Schroeder, Carl Bernhardt

309

Measurements of plasma potential in high-pressure microwave plasmas.  

PubMed

Plasma potential of a high-pressure ( approximately 1 Torr) microwave-generated argon plasma is measured using a Langmuir probe and a cold emissive probe. The operation of a hot emissive probe in a high-pressure plasma has been very difficult due to frequent burn-outs and significantly reduced lifetime of the probe filament, which, in turn, limits the possibility of collecting a wide range of data. The I-V characteristics from both Langmuir and emissive probes are interpreted using the collisionless probe theory since the collision correction factor is not very significant. The plasma potential determined from both Langmuir and cold emissive probe characteristics agrees well with one another and is observed to be dependent on the operating gas pressure but relatively unchanged as a function of the microwave power. An average plasma potential determined over the operating range of microwave powers varies nonlinearly with the gas pressure. PMID:19405659

Tarasova, A V; Podder, N K; Clothiaux, E J

2009-04-01

310

Measurements of plasma potential in high-pressure microwave plasmas  

SciTech Connect

Plasma potential of a high-pressure ({approx}1 Torr) microwave-generated argon plasma is measured using a Langmuir probe and a cold emissive probe. The operation of a hot emissive probe in a high-pressure plasma has been very difficult due to frequent burn-outs and significantly reduced lifetime of the probe filament, which, in turn, limits the possibility of collecting a wide range of data. The I-V characteristics from both Langmuir and emissive probes are interpreted using the collisionless probe theory since the collision correction factor is not very significant. The plasma potential determined from both Langmuir and cold emissive probe characteristics agrees well with one another and is observed to be dependent on the operating gas pressure but relatively unchanged as a function of the microwave power. An average plasma potential determined over the operating range of microwave powers varies nonlinearly with the gas pressure.

Tarasova, A. V.; Podder, N. K. [Department of Math and Physics, Troy University, Troy, Alabama 36082 (United States); Clothiaux, E. J. [Department of Physics, Auburn University, Auburn, Alabama 36849 (United States)

2009-04-15

311

Real-Time Plasma Control During KSTAR First Plasma  

NASA Astrophysics Data System (ADS)

Real-time control of Korea Superconducting Tokamak Advanced Research (KSTAR) discharges was successfully demonstrated during the KSTAR coil commissioning and first plasma period of May-June 2008. KSTAR, located at the National Fusion Research Institute (NFRI) in Daejeon, South Korea, is designed to explore steady-state, high-performance tokamak plasmas. The KSTAR plasma control system (PCS) was developed in a collaboration between General Atomics and NFRI, and derives from the PCS originally developed for DIII-D and currently in use at NSTX, MAST, EAST, Pegasus, and MST. A suite of electromagnetic analysis and plasma control design tools, closely integrated with the KSTAR PCS, were used extensively to support the startup campaign. Initial coil commissioning was completed successfully, utilizing the power supply voltage and current feedback algorithms. Plasma current, density, and rudimentary control of major radius was demonstrated during startup discharges.

Eidietis, N. W.; Hahn, S. H.; Oh, Y. K.; Humphreys, D. A.; Hyatt, A. W.; Leuer, J. A.; Walker, M. L.

2008-11-01

312

Cable guns as a plasma source in a plasma opening switch  

Microsoft Academic Search

The characteristics of a plasma generated by cable plasma guns have been studied by a laser interferometer. Cable plasma guns are frequently used as a plasma source in plasma opening switches. In our experiments, the plasma source consists of eight coaxial cable guns mounted on the outer electrode of concentric coaxial electrodes. The reproducibility of the gun in subsequent shots

Susumu Kohno; Yusuke Teramoto; Igor V. Lisitsyn; Sunao Katsuki; Hidenori Akiyama

1999-01-01

313

A dusty plasma device for producing extended, steady state, magnetized, dusty plasma columns  

E-print Network

A dusty plasma device for producing extended, steady state, magnetized, dusty plasma columns Wenjun with an existing Q machine, to produce extended, steady state, magnetized plasma columns. The dusty plasma device (DPD) is to be used for the investigation of waves in dusty plasmas and of other plasma/dust aspects

Merlino, Robert L.

314

Advanced computations in plasma physics  

Microsoft Academic Search

Scientific simulation in tandem with theory and experiment is an essential tool for understanding complex plasma behavior. In this paper we review recent progress and future directions for advanced simulations in magnetically confined plasmas with illustrative examples chosen from magnetic confinement research areas such as microturbulence, magnetohydrodynamics, magnetic reconnection, and others. Significant recent progress has been made in both particle

W. M. Tang

2002-01-01

315

Michigan Institute for Plasma Science  

E-print Network

in particular the recent emphasis on LTP biomedical applications, which introduces a new set of especially species ex change mass, momentum and energy with walls; the plasma electrostatic potential is referenced to wall potential; energetic and often chemically reactive charged and neutral species from the plasma

Shyy, Wei

316

Particle behavior in thermal plasmas  

Microsoft Academic Search

In this overview, effects exerted on the motion and on heat and mass transfer of particulates injected into a thermal plasma are discussed, including an assessment of their relative importance in the context of thermal plasma processing of materials. Results of computer experiments are shown for particle sizes ranging from 5–50 µm, and for alumina and tungsten as sample materials.

E. Pfender

1989-01-01

317

NRL Plasma Formulary: Revised 1998  

NSDL National Science Digital Library

The latest edition of the US Naval Research Laboratory's NRL Plasma Formulary, (discussed in the November 27, 1997 Scout Report) is available. This "mini-bible" for plasma physicists compiles a variety of pertinent mathematical and scientific formulas. Available in three formats, the formulary can be downloaded in its entirety or by thematic section.

318

Plasma theory and simulation research  

SciTech Connect

Our research group uses both theory and simulation as tools in order to increase the understanding of instabilities, heating, diffusion, transport and other phenomena in plasmas. We also work on the improvement of simulation, both theoretically and practically. Our focus has been more and more on the plasma edge (the sheath''), interactions with boundaries, leading to simulations of whole devices (someday a numerical tokamak).

Birdsall, C.K.

1989-01-01

319

The plasma enviroment of Neptune  

Microsoft Academic Search

This chapter describes the Voyager 2 plasma observations near Neptune. The authors describe features in the order they were observed by Voyager. The authors begin with an explanation of some of the more salient ideas of magnetospheric plasma physics used in this review and discuss some of the expectations for Neptune. They give an overview of the encounter data and

J. D. Richardson; J. W. Belcher; A. Szabo; R. L. McNutt Jr.

1995-01-01

320

Space plasma contactor research, 1987  

NASA Technical Reports Server (NTRS)

A simple model describing the process of electron collection from a low pressure ambient plasma in the absence of magnetic field and contactor velocity effects is presented. Experimental measurments of the plasma surrounding the contactor are used to demonstrate that a double-sheath generally develops and separates the ambient plasma from a higher density, anode plasma located adjacent to the contactor. Agreement between the predictions of the model and experimental measurements obtained at the electron collection current levels ranging to 1 A suggests the surface area at the ambient plasma boundary of the double-sheath is equal to the electron current being collected divided by the ambient plasma random electron current density; the surface area of the higher density anode plasma boundary of the double-sheath is equal to the ion current being emitted across this boundary divided by the ion current density required to sustain a stable sheath; and the voltage drop across the sheath is determined by the requirement that the ion and electron currents counterflowing across the boundaries be at space-charge limited levels. The efficiency of contactor operation is shown to improve when significant ionization and excitation is induced by electrons that stream from the ambient plasma through the double-sheath and collide with neutral atoms being supplied through the hollow cathode.

Wilbur, Paul J.

1988-01-01

321

Relativistic Laser-Plasma Interactions  

Microsoft Academic Search

Ever since the much acclaimed paper of Akhiezer and Polovin [1] plasma theorists have been attempting to comprehend complex dynamics related to the propagation of high and ultra-high intensity electromagnetic (EM) radiation through a plasma. This topic was successfully revisited a number of years later by Kaw and Dawson [2] whose analysis threw more light on the propagation of coupled

2009-01-01

322

Ultraintense laser-plasma interactions  

Microsoft Academic Search

Lasers currently under construction or completed carry laser-plasma interactions well into the relativistic regime, with intensities of high 1019 or 1020 Wcm-2. In such cases relativistic effects play a major role and may dominate the physics involved in the interaction. There are many plasma physics related applications which aim to make use of these new ultra intense short pulse lasers.

A. Dyson

1999-01-01

323

Supersonic induction plasma jet modeling  

NASA Astrophysics Data System (ADS)

Numerical simulations have been applied to study the argon plasma flow downstream of the induction plasma torch. It is shown that by means of the convergent-divergent nozzle adjustment and chamber pressure reduction, a supersonic plasma jet can be obtained. We investigate the supersonic and a more traditional subsonic plasma jets impinging onto a normal substrate. Comparing to the subsonic jet, the supersonic one is narrower and much faster. Near-substrate velocity and temperature boundary layers are thinner, so the heat flux near the stagnation point is higher in the supersonic jet. The supersonic plasma jet is characterized by the electron overpopulation and the domination of the recombination over the dissociation, resulting into the heating of the electron gas. Because of these processes, the supersonic induction plasma permits to separate spatially different functions (dissociation and ionization, transport and deposition) and to optimize each of them. The considered configuration can be advantageous in some industrial applications, such as plasma-assisted chemical vapor deposition of diamond and polymer-like films and in plasma spraying of nanoscaled powders.

Selezneva, S. E.; Boulos, M. I.

2001-06-01

324

Industrial applications of thermal plasmas  

Microsoft Academic Search

The main characteristics and applications of thermal plasmas are reviewed here. The industrial applications of thermal plasmas can be divided in: low power–cutting, welding, spraying; metallurgical and steelmaking; materials; environment. Some of the processes described in this article include: powder spraying, metal refining, tundish and laddle heating, production of ferroalloys and ceramic materials, and treatment of residues (aluminum scrap, steel

Roberto Nunes Szente

1995-01-01

325

Arcs, plasma torches and applications  

Microsoft Academic Search

The applications of arcs and plasma torches can be roughly classified in two domains: electrical engineering and thermal (or chemical) processes. In the first category we can consider circuit-breakers, arc lamps and some aspects concerning lightning. In the second category, we can distinguish metallurgical processes (cutting, welding, arc furnaces and metal heating), plasma spraying, particle production and treatment, fullerenes and

A. Gleizes; J. J. Gonzalez; M. Razafinimanana

2002-01-01

326

Industrial plasma torches and applications  

Microsoft Academic Search

Plasma technology has given a new direction and impetus to many industrial operations by opening up a new range of mechanical, chemical and metallur- gical processing techniques. The high temperatures together with the high reactivity due to the presence of free ions and radicals, make the plasma a powerful medium to promote high heat transfer rates and chemical reactions. This

N. Venkatramani

327

Plasma treatment advantages for textiles  

Microsoft Academic Search

The textile industry is searching for innovative production techniques to improve the product quality, as well as society requires new finishing techniques working in environmental respect. Plasma surface treatments show distinct advantages, because they are able to modify the surface properties of inert materials, sometimes with environment friendly devices. For fabrics, cold plasma treatments require the development of reliable and

Amelia Sparavigna

2008-01-01

328

Comparison of plasma focus calculations  

Microsoft Academic Search

A simple model for the current history of plasma focus experiments is presented. The presence of a leak current which does not pass through the plasma sheath is allowed. Results are found to compare quite well with those of much more sophisticated two-dimensional magnetohydrodynamic calculations. For the Frascati experiment, which has detailed current measurements, computed results do not agree with

P. G. Eltgroth

1982-01-01

329

The quark-gluon plasma  

Microsoft Academic Search

I present various aspects of the physics of the quark-gluon plasma. Known properties of the transition from hadronic matter to the quark-gluon plasma are recalled. Progress in the phenomenology of ultra-relativistic heavy ion collisions is discussed on two examples. Some recent theoretical developments are mentioned.

Jean-Paul Blaizot

1993-01-01

330

Plasma-heating by induction  

NASA Technical Reports Server (NTRS)

Induction-heated plasma torch operates with an input of 1 Mw of direct current of which 71 percent is transferred to the plasma and the remainder is consumed by electrical losses in the system. Continuous operation of the torch should be possible for as long as 5,000 hours.

Harrington, K.; Thorpe, M. L.

1969-01-01

331

Atmospheric-Pressure Plasma Process and Applications.  

National Technical Information Service (NTIS)

This paper provides a general discussion of atmospheric-pressure plasma generation, processes, and applications. There are two distinct categories of atmospheric-pressure plasmas: thermal and nonthermal. Thermal atmospheric-pressure plasmas include those ...

P. Kong

2006-01-01

332

Control of impurities in toroidal plasma devices  

DOEpatents

A method and apparatus for plasma impurity control in closed flux plasma systems such as Tokamak reactors is disclosed. Local axisymmetrical injection of hydrogen gas is employed to reverse the normally inward flow of impurities into the plasma.

Ohkawa, Tihiro (La Jolla, CA)

1980-01-01

333

21 CFR 866.2160 - Coagulase plasma.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Coagulase plasma. 866.2160 Section 866.2160 Food...Microbiology Devices § 866.2160 Coagulase plasma. (a) Identification. Coagulase plasma is a device that consists of...

2010-04-01

334

21 CFR 866.2160 - Coagulase plasma.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Coagulase plasma. 866.2160 Section 866.2160 Food...Microbiology Devices § 866.2160 Coagulase plasma. (a) Identification. Coagulase plasma is a device that consists of...

2012-04-01

335

21 CFR 866.2160 - Coagulase plasma.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Coagulase plasma. 866.2160 Section 866.2160 Food...Microbiology Devices § 866.2160 Coagulase plasma. (a) Identification. Coagulase plasma is a device that consists of...

2011-04-01

336

21 CFR 866.2160 - Coagulase plasma.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Coagulase plasma. 866.2160 Section 866.2160 Food...Microbiology Devices § 866.2160 Coagulase plasma. (a) Identification. Coagulase plasma is a device that consists of...

2013-04-01

337

21 CFR 866.2160 - Coagulase plasma.  

...2014-04-01 2014-04-01 false Coagulase plasma. 866.2160 Section 866.2160 Food...Microbiology Devices § 866.2160 Coagulase plasma. (a) Identification. Coagulase plasma is a device that consists of...

2014-04-01

338

Current Drive in Recombining Plasma  

SciTech Connect

The Langevin equations describing the average collisional dynamics of suprathermal particles in nonstationary plasma remarkably admit an exact analytical solution in the case of recombining plasma. The current density produced by arbitrary particle fluxes is derived including the effect of charge recombination. Since recombination has the effect of lowering the charge density of the plasma, thus reducing the charged particle collisional frequencies, the evolution of the current density can be modified substantially compared to plasma with fixed charge density. The current drive efficiency is derived and optimized for discrete and continuous pulses of current, leading to the discovery of a nonzero "residual" current density that persists indefinitely under certain conditions, a feature not present in stationary plasmas.

P.F. Schmit and N.J. Fisch

2012-05-15

339

Current drive in recombining plasma  

SciTech Connect

The Langevin equations describing the average collisional dynamics of suprathermal particles in nonstationary plasma remarkably admit an exact analytical solution in the case of recombining plasma. The current density produced by arbitrary particle fluxes is derived including the influence of charge recombination. Since recombination has the effect of lowering the charge density of the plasma, thus reducing the charged particle collisional frequencies, the evolution of the current density can be modified substantially compared to plasma with fixed charge density. The current drive efficiency is derived and optimized for discrete and continuous pulses of current, leading to the discovery of a nonzero ''residual'' current density that persists indefinitely under certain conditions, a feature not present in stationary plasmas.

Schmit, P. F.; Fisch, N. J. [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States)

2011-10-15

340

Helicon plasma thruster discharge model  

NASA Astrophysics Data System (ADS)

By considering particle, momentum, and energy balance equations, we develop a semi-empirical quasi one-dimensional analytical discharge model of radio-frequency and helicon plasma thrusters. The model, which includes both the upstream plasma source region as well as the downstream diverging magnetic nozzle region, is compared with experimental measurements and confirms current performance levels. Analysis of the discharge model identifies plasma power losses on the radial and back wall of the thruster as the major performance reduction factors. These losses serve as sinks for the input power which do not contribute to the thrust, and which reduce the maximum plasma density and hence propellant utilization. With significant radial plasma losses eliminated, the discharge model (with argon) predicts specific impulses in excess of 3000 s, propellant utilizations above 90%, and thruster efficiencies of about 30%.

Lafleur, T.

2014-04-01

341

Industrial applications of thermal plasmas  

NASA Astrophysics Data System (ADS)

The main characteristics and applications of thermal plasmas are reviewed here. The industrial applications of thermal plasmas can be divided in: low power-cutting, welding, spraying; metallurgical and steelmaking; materials; environment. Some of the processes described in this article include: powder spraying, metal refining, tundish and laddle heating, production of ferroalloys and ceramic materials, and treatment of residues (aluminum scrap, steel dusts, ashes, hospital wastes, electroplating mud). The use of thermal plasmas in the environment arena in particular has attracted increasingly attention as the regulations for disposal of residues become tougher. More research and development is needed particularly for decreasing the erosion of the electrodes of plasma torches and fundamental understanding of high temperature chemistry, heat transfer, and electric arcs for broadening the applications of thermal plasmas.

Szente, Roberto Nunes

1995-09-01

342

Cyclic olefin copolymer plasma millireactors.  

PubMed

The novelty of this paper lies in the development of a multistep process for the manufacturing of plasma millireactors operating at atmospheric pressure. The fabrication process relies on the integration of metallic electrodes over a cyclic olefin copolymer chip by a combination of photopatterning and sputtering. The developed plasma millireactors were successfully tested by creating air discharges in the gas volume of the millichannel. A sputtered silica layer was deposited on the channel walls to provide a barrier between the plasma and the polymer in order to prevent the alteration of polymer surfaces during the plasma treatment. Interest in this process of employing plasma millireactor as a high reactive environment is demonstrated here by the degradation of a volatile organic compound (acetaldehyde) in ambient air. In this miniaturized device, we obtained a high acetaldehyde conversion (98%) for a specific input energy lower than 200 J L(-1). PMID:24957952

Schelcher, G; Guyon, C; Ognier, S; Cavadias, S; Martinez, E; Taniga, V; Malaquin, L; Tabeling, P; Tatoulian, M

2014-08-21

343

Plasma treatment advantages for textiles  

E-print Network

The textile industry is searching for innovative production techniques to improve the product quality, as well as society requires new finishing techniques working in environmental respect. Plasma surface treatments show distinct advantages, because they are able to modify the surface properties of inert materials, sometimes with environment friendly devices. For fabrics, cold plasma treatments require the development of reliable and large systems. Such systems are now existing and the use of plasma physics in industrial problems is rapidly increasing. On textile surfaces, three main effects can be obtained depending on the treatment conditions: the cleaning effect, the increase of microroughness (anti-pilling finishing of wool) and the production of radicals to obtain hydrophilic surfaces. Plasma polymerisation, that is the deposition of solid polymeric materials with desired properties on textile substrates, is under development. The advantage of such plasma treatments is that the modification turns out to ...

Sparavigna, Amelia

2008-01-01

344

Photovoltaic Plasma Interaction Test 2  

NASA Technical Reports Server (NTRS)

The International Space Station (ISS) program is developing a plasma contactor to mitigate the harmful effects of charge collection on the station's large photovoltaic arrays. The purpose of the present test was to examine the effects of charge collection on the solar array electrical circuit and to verify the effectiveness of the plasma contactor. The results showed that the plasma contactor was able to eliminate structure arcing for any array output voltage. However, the current requirements of the plasma contactor were higher than those for prior testing and predicted by analysis. Three possible causes for this excess current demand are discussed. The most likely appeared to be a high local pressure on or very near the surface of the array as a result of vacuum tank conditions. Therefore, in actual space conditions, the plasma contactor should work as predicted.

Kaufman, Bradford A.; Chrulski, Daniel; Myers, Roger M.

1996-01-01

345

Resonant-cavity antenna for plasma heating  

DOEpatents

This invention relates generally to a method and apparatus for transferring energy to a plasma immersed in a magnetic field, and relates particularly to an apparatus for heating a plasma of low atomic number ions to high temperatures by transfer of energy to plasma resonances, particularly the fundamental and harmonics of the ion cyclotron frequency of the plasma ions. This invention transfers energy from an oscillating radio-frequency field to a plasma resonance of a plasma immersed in a magnetic field.

Perkins, F.W. Jr.; Chiu, S.C.; Parks, P.; Rawls, J.M.

1984-01-10

346

Research in plasma physics  

NASA Technical Reports Server (NTRS)

Three aspects of barium ion cloud dynamics are discussed. First, the effect of the ratio of ion cloud conductivity to background ionospheric conductivity on the motion of barium ion clouds is investigated and compared with observations of barium ion clouds. This study led to the suggestion that the conjugate ionosphere participates in the dynamics of barium ion clouds. Second, analytic work on the deformation of ion clouds is presented. Third, a linearized stability theory was extended to include the effect of the finite extent of an ion cloud, as well as the effect of the ratio of ion cloud to ionospheric conductivities. The stability properties of a plasma with contra-streaming ion beams parallel to a magnetic field are investigated. The results are interpreted in terms of parameters appropriate for collisionless shock waves. It is found that this particular instability can be operative only if the up-stream Alfven Mach number exceeds 5.5.

1973-01-01

347

Magnetospheric space plasma investigations  

NASA Technical Reports Server (NTRS)

A time dependent semi-kinetic model that includes self collisions and ion-neutral collisions and chemistry was developed. Light ion outflow in the polar cap transition region was modeled and compared with data results. A model study of wave heating of O+ ions in the topside transition region was carried out using a code which does local calculations that include ion-neutral and Coulomb self collisions as well as production and loss of O+. Another project is a statistical study of hydrogen spin curve characteristics in the polar cap. A statistical study of the latitudinal distribution of core plasmas along the L=4.6 field line using DE-1/RIMS data was completed. A short paper on dual spacecraft estimates of ion temperature profiles and heat flows in the plasmasphere ionosphere system was prepared. An automated processing code was used to process RIMS data from 1981 to 1984.

Comfort, Richard H.; Horwitz, James L.

1994-01-01

348

Solid state plasmas  

E-print Network

Magnetic fusion devices operate at regimes characterized by extremely high temperatures and low densities, for which the charged particles motion is well described by classical mechanics. This is not true, however, for solid-state metallic objects: their density approaches $10^{28} \\rm m^{-3}$, so that the average interparticle distance is shorter than the de Broglie wavelength, which characterizes the spread of the electron wave function. Under these conditions, the conduction electrons behave as a true quantum plasma even at room temperature. Here, we shall illustrate the impact of quantum phenomena on the electron dynamics in metallic objects of nanometric size, particularly thin metallic films excited by short laser pulses. Further, we will discuss more recent results on regimes that involve spin and relativistic effects.

Manfredi, Giovanni

2014-01-01

349

Surface plasma source with anode layer plasma acceleratora)  

NASA Astrophysics Data System (ADS)

Proposed plasma generation system can be used for high current negative ion beam production and for directed deposition by flux of sputtered neutrals and negative ions. The main mechanism of negative ion formation in surface plasma sources is the secondary emission from low work function surface bombarded by a flux of positive ion or neutrals. The emission of negative ions is enhanced significantly by introducing a small amount of cesium or other substance with low ionization potential. In the proposed source are used positive ions generated by Hall drift plasma accelerator (anode layer plasma accelerator or plasma accelerator with insulated channel, with cylindrical or race track configuration of emission slit). The target-emitter is bombarded by the ion beam accelerated in crossed ExB fields. Negative ions are extracted from the target surface with geometrical focusing and are accelerated by negative voltage applied between emitter and plasma, contacting with the plasma accelerator. Hall drift ion source has a special design with a space for passing of the emitted negative ions and sputtered particles through the positive ion source.

Dudnikov, Vadim

2012-02-01

350

Surface plasma source with anode layer plasma accelerator.  

PubMed

Proposed plasma generation system can be used for high current negative ion beam production and for directed deposition by flux of sputtered neutrals and negative ions. The main mechanism of negative ion formation in surface plasma sources is the secondary emission from low work function surface bombarded by a flux of positive ion or neutrals. The emission of negative ions is enhanced significantly by introducing a small amount of cesium or other substance with low ionization potential. In the proposed source are used positive ions generated by Hall drift plasma accelerator (anode layer plasma accelerator or plasma accelerator with insulated channel, with cylindrical or race track configuration of emission slit). The target-emitter is bombarded by the ion beam accelerated in crossed ExB fields. Negative ions are extracted from the target surface with geometrical focusing and are accelerated by negative voltage applied between emitter and plasma, contacting with the plasma accelerator. Hall drift ion source has a special design with a space for passing of the emitted negative ions and sputtered particles through the positive ion source. PMID:22380222

Dudnikov, Vadim

2012-02-01

351

Meter scale plasma source for plasma wakefield experiments  

SciTech Connect

High accelerating gradients generated by a high density electron beam moving through plasma has been used to double the energy of the SLAC electron beam [1]. During that experiment, the electron current density was high enough to generate its own plasma without significant head erosion. In the newly commissioned FACET facility at SLAC, the peak current will be lower and without pre-ionization, head erosion will be a significant challenge for the planned experiments. In this work we report on our design of a meter scale plasma source for these experiments to effectively avoid the problem of head erosion. The plasma source is based on a homogeneous metal vapor gas column that is generated in a heat pipe oven [2]. A lithium oven over 30 cm long at densities over 10{sup 17} cm{sup -3} has been constructed and tested at UCLA. The plasma is then generated by coupling a 10 TW short pulse Ti:Sapphire laser into the gas column using an axicon lens setup. The Bessel profile of the axicon setup creates a region of high intensity that can stretch over the full length of the gas column with approximately constant diameter. In this region of high intensity, the alkali metal vapor is ionized through multi-photon ionization process. In this manner, a fully ionized meter scale plasma of uniform density can be formed. Methods for controlling the plasma diameter and length will also be discussed.

Vafaei-Najafabadi, N.; Shaw, J. L.; Marsh, K. A.; Joshi, C.; Hogan, M. J. [Department of Electrical Engineering, University of California Los Angeles, Los Angeles, CA 90095 (United States); SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States)

2012-12-21

352

NCSX Plasma Heating Methods  

SciTech Connect

The National Compact Stellarator Experiment (NCSX) has been designed to accommodate a variety of heating systems, including ohmic heating, neutral beam injection, and radio-frequency (rf). Neutral beams will provide one of the primary heating methods for NCSX. In addition to plasma heating, neutral beams are also expected to provide a means for external control over the level of toroidal plasma rotation velocity and its profile. The experimental plan requires 3 MW of 50-keV balanced neutral beam tangential injection with pulse lengths of 500 ms for initial experiments, to be upgradeable to pulse lengths of 1.5 s. Subsequent upgrades will add 3MW of neutral beam injection (NBI). This paper discusses the NCSX NBI requirements and design issues and shows how these are provided by the candidate PBX-M NBI system. In addition, estimations are given for beam heating efficiencies, scaling of heating efficiency with machine size and magnetic field level, parameter studies of the optimum beam injection tangency radius and toroidal injection location, and loss patterns of beam ions on the vacuum chamber wall to assist placement of wall armor and for minimizing the generation of impurities by the energetic beam ions. Finally, subsequent upgrades could add an additional 6 MW of rf heating by mode conversion ion Bernstein wave (MCIBW) heating, and if desired as possible future upgrades, the design also will accommodate high-harmonic fast-wave and electron cyclotron heating. The initial MCIBW heating technique and the design of the rf system lend themselves to current drive, so if current drive became desirable for any reason, only minor modifications to the heating system described here would be needed. The rf system will also be capable of localized ion heating (bulk or tail), and possiblyIBW-generated sheared flows.

H.W. Kugel, D. Spong, R. Majeski and M. Zarnstorff

2008-01-18

353

PlasmaLab/Eco-Plasma - The future of complex plasma research in space  

NASA Astrophysics Data System (ADS)

The next Russian-German cooperation for the investigation of complex plasmas under microgravity conditions on the International Space Station (ISS) is the PlasmaLab/Eco-Plasma project. Here, a new plasma chamber -- the ``Zyflex'' chamber -- is being developed. The chamber is a cylindrical plasma chamber with parallel electrodes and a flexible system geometry. It is designed to extend the accessible plasma parameter range, i.e. neutral gas pressure, plasma density and electron temperature, and also to allow an independent control of the plasma parameters, therefore increasing the experimental quality and expected knowledge gain significantly. With this system it will be possible to reach low neutral gas pressures (which means weak damping of the particle motion) and to generate large, homogeneous 3D particle systems for studies of fundamental phenomena such as phase transitions, dynamics of liquids or phase separation. The Zyflex chamber has already been operated in several parabolic flight campaigns with different configurations during the last years, yielding a promising outlook for its future development. Here, we will present the current status of the project, the technological advancements the Zyflex chamber will offer compared to its predecessors, and the latest scientific results from experiments on ground and in microgravity conditions during parabolic flights. This work and some of the authors are funded by DLR/BMWi (FKZ 50 WP 0700).

Knapek, Christina; Thomas, Hubertus; Huber, Peter; Mohr, Daniel; Hagl, Tanja; Konopka, Uwe; Lipaev, Andrey; Morfill, Gregor; Molotkov, Vladimir

354

Negative Plasma Densities Raise Questions  

SciTech Connect

Nearly all the matter encountered on Earth is either a solid, liquid, or gas. Yet plasma-the fourth state of matter-comprises more than 99 percent of the visible universe. Understanding the physical characteristics of plasmas is important to many areas of scientific research, such as the development of fusion as a clean, renewable energy source. Lawrence Livermore scientists study the physics of plasmas in their pursuit to create fusion energy, because plasmas are an integral part of that process. When deuterium and tritium are heated to the extreme temperatures needed to achieve and sustain a fusion reaction (about 100 million degrees), the electrons in these light atoms become separated from the nuclei. This process of separation is called ionization, and the resulting collection of negatively charged free electrons and positively charged nuclei is known as a plasma. Although plasmas and gases have many similar properties, plasmas differ from gases in that they are good conductors of electricity and can generate magnetic fields. For the past decade, x-ray laser interferometry has been used in the laboratory for measuring a plasma's index of refraction to determine plasma density. (The index of refraction for a given material is defined as the wavelength of light in a vacuum divided by the wavelength of light traveling through the material.) Until now, plasma physicists expected to find an index of refraction less than one. Researchers from Livermore and Colorado State University recently conducted experiments on aluminum plasmas at the Laboratory's COMET laser facility and observed results in which the index of refraction was greater than one. This surprising result implied a negative electron density. Livermore physicist Joseph Nilsen and his colleagues from Livermore and the University of Notre Dame have performed sophisticated calculations to explain this phenomenon. Previously, researchers believed that only free electrons contributed to the index of refraction. Nilsen and his colleagues posit that bound electrons attached to the ions in plasmas can greatly affect the index of refraction and make it greater than one. Furthermore, if the effect of bound electrons is ignored when analyzing experimental results from x-ray interferometry, the electron density of plasmas may be indeterminate or significantly under- or overestimated.

Hazi, A

2006-01-26

355

Laser-induced plasma temperature  

NASA Astrophysics Data System (ADS)

It is of great importance to explore the evolution of laser-induced plasma (LIP) properties, especially plasma temperature, with regard to variations of experiment conditions in both theoretical study and routine applications. By investigating the influence of various factors on plasma temperature, one can gain knowledge about the processes in plasma and adjust experimental conditions to obtain optimum analytical performance. Herein the fundamental theories and calculation methods of LIP temperature via spectroscopic approaches are briefly reviewed. Its temporal and spatial evolutions together with several influencing factors are discussed, such as laser parameters, ambient surrounding, and physical & chemical properties of the sample. The results summarized exhibit the general trend that LIP temperature increases with increasing laser wavelength, pulse width, laser energy, background gas pressure, and sample hardness. On the other hand, it decreases with time elapsing and distance from sample surface. Moreover, plasma temperature generated in argon surrounding is higher than that in other gas species, and the rank of temperature values generated from different samples exhibits a general tendency of Cu > Fe > Ni ? Al ? glass ? rock. Additionally, LIP temperature tends to increase as lens focal point approaches sample surface, and the plasma confinement effect in sample cavity is significant in altering plasma temperature. Various explanations are given to interpret these temperature behaviors.

Zhang, Shudi; Wang, Xiaohua; He, Miaohong; Jiang, Yunbin; Zhang, Bochao; Hang, Wei; Huang, Benli

2014-07-01

356

Plasma Treatments and Biomass Gasification  

NASA Astrophysics Data System (ADS)

Exploitation of forest resources for energy production includes various methods of biomass processing. Gasification is one of the ways to recover energy from biomass. Syngas produced from biomass can be used to power internal combustion engines or, after purification, to supply fuel cells. Recent studies have shown the potential to improve conventional biomass processing by coupling a plasma reactor to a pyrolysis cyclone reactor. The role of the plasma is twofold: it acts as a purification stage by reducing production of tars and aerosols, and simultaneously produces a rich hydrogen syngas. In a first part of the paper we present results obtained from plasma treatment of pyrolysis oils. The outlet gas composition is given for various types of oils obtained at different experimental conditions with a pyrolysis reactor. Given the complexity of the mixtures from processing of biomass, we present a study with methanol considered as a model molecule. This experimental method allows a first modeling approach based on a combustion kinetic model suitable to validate the coupling of plasma with conventional biomass process. The second part of the paper is summarizing results obtained through a plasma-pyrolysis reactor arrangement. The goal is to show the feasibility of this plasma-pyrolysis coupling and emphasize more fundamental studies to understand the role of the plasma in the biomass treatment processes.

Luche, J.; Falcoz, Q.; Bastien, T.; Leninger, J. P.; Arabi, K.; Aubry, O.; Khacef, A.; Cormier, J. M.; Lédé, J.

2012-02-01

357

Nonlinear ICRF-Plasma Interactions  

SciTech Connect

The well developed linear theory of ICRF (including FW, HHFW and IBW) interactions with plasma has enjoyed considerable success in describing antenna coupling and wave propagation, and provides a well-known framework for calculating power absorption, current drive, etc. In some situations, less well studied nonlinear effects are of interest, such as flow drive, ponderomotive forces, rf sheaths, parametric decay and related interactions with the edge plasma. Standard ICRF codes have begun to integrate this physics to achieve improved modeling capabilities. This paper concentrates on basic rf-plasma-interaction physics with illustrative applications to tokamaks. For FW antennas, the parallel electric field near launching structures is known to drive rf-sheaths which can give rise to convective cells, interaction with plasma 'blobs', impurity production, and edge power dissipation. In addition to sheaths, IBW waves in the edge plasma are subject to strong ponderomotive effects and parametric decay. In the core plasma, slow waves can sometimes induce nonlinear effects. Mechanisms by which these waves can influence the radial electric field and its shear are summarized, and related to the general (reactive-ponderomotive and dissipative) force on a plasma from rf waves. It is argued that there are significant opportunities now for new predictive capabilities by advances in integrated simulation.

Myra, J.R.; D'Ippolito, D.A.; Russell, D.A.; Berry, L.A.; Jaeger, E.F.; Carter, M.D. [Lodestar Research Corporation, Boulder, Colorado (United States); Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States)

2005-09-26

358

Plasma medicine: an introductory review  

NASA Astrophysics Data System (ADS)

This introductory review on plasma health care is intended to provide the interested reader with a summary of the current status of this emerging field, its scope, and its broad interdisciplinary approach, ranging from plasma physics, chemistry and technology, to microbiology, biochemistry, biophysics, medicine and hygiene. Apart from the basic plasma processes and the restrictions and requirements set by international health standards, the review focuses on plasma interaction with prokaryotic cells (bacteria), eukaryotic cells (mammalian cells), cell membranes, DNA etc. In so doing, some of the unfamiliar terminology—an unavoidable by-product of interdisciplinary research—is covered and explained. Plasma health care may provide a fast and efficient new path for effective hospital (and other public buildings) hygiene—helping to prevent and contain diseases that are continuously gaining ground as resistance of pathogens to antibiotics grows. The delivery of medically active 'substances' at the molecular or ionic level is another exciting topic of research through effects on cell walls (permeabilization), cell excitation (paracrine action) and the introduction of reactive species into cell cytoplasm. Electric fields, charging of surfaces, current flows etc can also affect tissue in a controlled way. The field is young and hopes are high. It is fitting to cover the beginnings in New Journal of Physics, since it is the physics (and non-equilibrium chemistry) of room temperature atmospheric pressure plasmas that have made this development of plasma health care possible.

Kong, M. G.; Kroesen, G.; Morfill, G.; Nosenko, T.; Shimizu, T.; van Dijk, J.; Zimmermann, J. L.

2009-11-01

359

Plasma gasification of biomedical waste  

SciTech Connect

Resorption Canada Limited (RCL) has operated a plasma gasification installation near Ottawa, Ontario, Canada for over ten years; therefore, the salient capabilities and advantages of plasma gasification over other state-of-the-art technologies for environmentally cleaner disposal of a number of waste materials became increasingly clearer as more and more experience was gained. Plasma gasification is a non-incineration thermal process which uses extremely high temperatures to completely decompose input waste material into very simple molecules. The capability to generate such high heat without using oxygen, unlike a combustion flame, and the temperature profile of the hot plasma gases being between 3,000 C and 8,000 C was ideal for the disposal of waste materials through gasification. RCL conducted two major plasma gasification projects with Municipal Solid Waste (MSW) which were highly successful, indicating very clearly that the basic technology for plasma gasification was a very viable alternative to conventional incineration techniques with resultant environmental benefits related to gaseous emission levels and slag properties. The experimentation ended with two tests which included full environmental analyses for each. These results provided the initiative for similar testing with biomedical waste. The work on the plasma gasification of biomedical waste is summarized. The work on MSW is presented in a separate paper.

Carter, G.W.; Tsangaris, A.V.

1995-12-31

360

Plasma opening switch conduction scaling  

SciTech Connect

Plasma opening switch (POS) experiments performed on the Hawk generator [Commisso {ital et} {ital al}., Phys. Fluids B {bold 4}, 2368 (1992)] (750 kA, 1.2 {mu}s) determine the dependence of the conduction current and conduction time on plasma density, electrode dimensions, and current rise rate. The experiments indicate that for a range of parameters, conduction is controlled by magnetohydrodynamic (MHD) distortion of the plasma, resulting in a low density region where opening can occur, possibly by erosion. The MHD distortion corresponds to an axial translation of the plasma center-of-mass by half the initial plasma length, leading to a simple scaling relation between the conduction current and time, and the injected plasma density and POS electrode dimensions that is applicable to a large number of POS experiments. For smaller currents and conduction times, the Hawk data suggest a non-MHD conduction limit that may correspond to electromagnetohydrodynamic (EMH) field penetration through the POS plasma. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Weber, B.V.; Commisso, R.J.; Goodrich, P.J.; Grossmann, J.M.; Hinshelwood, D.D.; Ottinger, P.F.; Swanekamp, S.B. [Pulsed Power Physics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375-5000 (United States)] [Pulsed Power Physics Branch, Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375-5000 (United States)

1995-10-01

361

Atmospheric-pressure plasma jet  

DOEpatents

Atmospheric-pressure plasma jet. A .gamma.-mode, resonant-cavity plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes are employed to generate a plasma in the annular region therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode. Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike low-pressure plasma sources and conventional plasma processing methods.

Selwyn, Gary S. (Los Alamos, NM)

1999-01-01

362

Liquid injection plasma deposition method and apparatus  

DOEpatents

A liquid injection plasma torch deposition apparatus for depositing material onto a surface of a substrate may comprise a plasma torch for producing a jet of plasma from an outlet nozzle. A plasma confinement tube having an inlet end and an outlet end and a central bore therethrough is aligned with the outlet nozzle of the plasma torch so that the plasma jet is directed into the inlet end of the plasma confinement tube and emerges from the outlet end of the plasma confinement tube. The plasma confinement tube also includes an injection port transverse to the central bore. A liquid injection device connected to the injection port of the plasma confinement tube injects a liquid reactant mixture containing the material to be deposited onto the surface of the substrate through the injection port and into the central bore of the plasma confinement tube. 8 figs.

Kong, P.C.; Watkins, A.D.

1999-05-25

363

Liquid injection plasma deposition method and apparatus  

DOEpatents

A liquid injection plasma torch deposition apparatus for depositing material onto a surface of a substrate may comprise a plasma torch for producing a jet of plasma from an outlet nozzle. A plasma confinement tube having an inlet end and an outlet end and a central bore therethrough is aligned with the outlet nozzle of the plasma torch so that the plasma jet is directed into the inlet end of the plasma confinement tube and emerges from the outlet end of the plasma confinement tube. The plasma confinement tube also includes an injection port transverse to the central bore. A liquid injection device connected to the injection port of the plasma confinement tube injects a liquid reactant mixture containing the material to be deposited onto the surface of the substrate through the injection port and into the central bore of the plasma confinement tube.

Kong, Peter C. (Idaho Falls, ID); Watkins, Arthur D. (Idaho Falls, ID)

1999-01-01

364

TOPICAL REVIEW: Thermal plasma modelling  

NASA Astrophysics Data System (ADS)

Electrical arcs and, more generally thermal plasmas, are widely used in many applications and the understanding or the improvement of the corresponding processes or systems, often requires precise modelling of the plasma. We present, here, a double approach to thermal plasma modelling, which combines the scientific procedure with an engineering point of view. First, we present the fundamental properties of thermal plasmas that are required in the models, followed by the basic equations and structures of the models. The third part is devoted to test cases, and its objectives are the study of some basic phenomena to show their influence on arc behaviour in simple configurations, and the validation of the models: we point out the roles of radiation, thermal conductivity and electrical conductivity for a stationary or transient wall-stabilized arc and we validate a three-dimensional model for a free-burning arc. Sections 4-6 deal with several industrial configurations and the model is useful in each case for studying important phenomena or processes in greater detail. For transferred arcs, such as those used in metallurgy, the energy transfer from the arc to the anode, and the presence of metallic vapour and pumping gas are essential. For a non-transferred plasma torch used for plasma spraying, we illustrate the relevance of a three-dimensional model and we present the interaction of the plasma with powders. Problems related to high- and low-voltage circuit-breakers are then presented, and various typical mechanisms are modelled. Finally, several non-equilibrium models useful for quasi-thermal conditions are presented in detail, showing how they take into account the chemical kinetics and two-temperature plasmas occurring under particular conditions, such as decaying arcs or inductively coupled plasmas.

Gleizes, A.; Gonzalez, J. J.; Freton, P.

2005-05-01

365

Plasma acceleration processes in an ablative pulsed plasma thruster  

SciTech Connect

Plasma acceleration processes in an ablative pulsed plasma thruster (APPT) were investigated. APPTs are space propulsion options suitable for microspacecraft, and have recently attracted much attention because of their low electric power requirements and simple, compact propellant system. The plasma acceleration mechanism, however, has not been well understood. In the present work, emission spectroscopy, high speed photography, and magnetic field measurements are conducted inside the electrode channel of an APPT with rectangular geometry. The successive images of neutral particles and ions give us a comprehensive understanding of their behavior under electromagnetic acceleration. The magnetic field profile clarifies the location where the electromagnetic force takes effect. As a result, it is shown that high density, ablated neutral gas stays near the propellant surface, and only a fraction of the neutrals is converted into plasma and electromagnetically accelerated, leaving the residual neutrals behind.

Koizumi, Hiroyuki; Noji, Ryosuke; Komurasaki, Kimiya; Arakawa, Yoshihiro [Department of Aeronautics and Astronautics, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Advanced Energy, University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan); Department of Aeronautics and Astronautics, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2007-03-15

366

The Absence of Plasma in"Spark Plasma Sintering"  

SciTech Connect

Spark plasma sintering (SPS) is a remarkable method for synthesizing and consolidating a large variety of both novel and traditional materials. The process typically uses moderate uni-axial pressures (<100 MPa) in conjunction with a pulsing on-off DC current during operation. There are a number of mechanisms proposed to account for the enhanced sintering abilities of the SPS process. Of these mechanisms, the one most commonly put forth and the one that draws the most controversy involves the presence of momentary plasma generated between particles. This study employees three separate experimental methods in an attempt to determine the presence or absence of plasma during SPS. The methods employed include: in-situ atomic emission spectroscopy, direct visual observation and ultra-fast in-situ voltage measurements. It was found using these experimental techniques that no plasma is present during the SPS process. This result was confirmed using several different powders across a wide spectrum of SPS conditions.

Hulbert, Dustin M.; Anders, Andre; Dudina, Dina V.; Andersson, Joakim; Jiang, Dongtao; Unuvar, Cosan; Anselmi-Tamburini, Umberto; Lavernia, Enrique J.; Mukherjee, Amiya K.

2008-04-10

367

Effect of plasma surface interactions on PLT plasma parameters  

SciTech Connect

This paper gives a brief description of the geometry and parameters of the PLT tokamak, reviews some of the last four years' results that are particularly relevant to plasma-boundary interactions, and then concentrates on two specific problems.

Meservey, E.B.; Arunasalam, V.; Barnes, C.

1980-07-01

368

Surface plasma source with saddle antenna radio frequency plasma generator  

SciTech Connect

A prototype RF H{sup -} surface plasma source (SPS) with saddle (SA) RF antenna is developed which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with small AlN discharge chambers and different antennas and magnetic field configurations were tested in the plasma source test stand. A prototype SA SPS was installed in the Spallation Neutron Source (SNS) ion source test stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency up to 1.6 mA/kW. Control experiments with H{sup -} beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma gun has been designed. A saddle antenna SPS with water cooling is fabricated for high duty factor testing.

Dudnikov, V.; Johnson, R. P. [Muons, Inc., Batavia, Illinios 60510 (United States); Murray, S.; Pennisi, T.; Piller, C.; Santana, M.; Stockli, M.; Welton, R. [ORNL, Oak Ridge, Tennessee 37831 (United States)

2012-02-15

369

Interactions between satellites and plasma  

NASA Technical Reports Server (NTRS)

The interactions of a spacecraft with the surrounding, streaming plasma were determined by the following effects: the fade out of the plasma in the wake of the probe, the emission of photoelectrons and secondary electrons, the differential charging of the surface of the probe, and a spatial potential distribution in the vicinity of the space probe. These effects and their importance are discussed and following plasma conditions are considered: (1) geostationary satellite orbits; (2) in the solar wind (HELIOS mission); and (3) in the ionosphere at an altitude of 250 km (the projected OSV on Spacelab). The fundamental models are reviewed.

Isensee, U.; Lehr, W.; Maassberg, H.

1984-01-01

370

Laboratory experiments on plasma contactors  

NASA Technical Reports Server (NTRS)

Experimental results describing the operation of hollow cathode plasma contactors collecting and emitting electrons from and to an ambient plasma at current levels of the order of one ampere are presented. The voltage drops induced between a contactor and an ambient plasma are shown to be a few tens of volts at such current levels. The development of a double sheath and the production of substantial numbers of ions by electrons streaming across it are associated with the electron collection process. The development of a complex potential structure including a high potential hill just downstream of the cathode orifice is shown to characterize typical contactor emitting electrons.

Wilbur, Paul J.; Williams, John D.

1990-01-01

371

Radiation reaction in fusion plasmas.  

PubMed

The effects of a radiation reaction on thermal electrons in a magnetically confined plasma, with parameters typical of planned burning plasma experiments, are studied. A fully relativistic kinetic equation that includes the radiation reaction is derived. The associated rate of phase-space contraction is computed and the relative importance of the radiation reaction in phase space is estimated. A consideration of the moments of the radiation reaction force show that its effects are typically small in reactor-grade confined plasmas, but not necessarily insignificant. PMID:15600530

Hazeltine, R D; Mahajan, S M

2004-10-01

372

Resonant Excitation of Plasma Wakefields  

SciTech Connect

We describe characteristics of the bunch train and plasma source used in a resonant plasma wakefield experiment at the Brookhaven National Laboratory Accelerator Test Facility. The bunch train has the proper correlated spread to unambiguously observe the expected energy gain by the witness bunch at resonance. The plasma density in the capillary discharge is sufficiently high to reach the resonance with the typical bunch train spacing of this experiment. It is also uniform over more than 3/4 of the 2 cm-long capillary.

Muggli, P.; Allen, B. [University of Southern California, Los Angeles, CA 90089 (United States); Yakimenko, V.; Fedurin, M.; Kusche, K.; Babzien, M. [Brookhaven National Laboratory, Upton, NY 11973 (United States)

2010-11-04

373

Plasma Gate: Free Software for Atomic and Plasma Physics  

NSDL National Science Digital Library

Maintained by the Plasma Laboratory of Weizmann Institute of Science, the Free Software for Atomic and Plasma Physics Web site contains over thirty links to various programs. Examples of available software include Weizmann Institutes: 369j-symbol calculator and Russia's Institute of Spectroscopy's spectral bibliography database. Although several of the links currently seem to be dead, the site does give those working in this field access to several sites with useful software programs.

1994-01-01

374

The Diagnostics of the External Plasma for the Plasma Rocket  

NASA Technical Reports Server (NTRS)

The plasma rocket is located at NASA Johnson Space Center. To produce a thrust in space. an inert gas is ionized into a plasma and heated in the linear section of a tokamak fusion device to 1 x 10(exp 4) - 1.16 x 10(exp 6)K(p= 10(exp 10) - 10(exp 14)/cu cm ). The magnetic field used to contain the plasma has a magnitude of 2 - 10k Gauss. The plasma plume has a variable thrust and specific impulse. A high temperature retarding potential analyzer (RPA) is being developed to characterize the plasma in the plume and at the edge of the magnetically contained plasma. The RPA measures the energy and density of ions or electrons entering into its solid angle of collection. An oscilloscope displays the ion flux versus the collected current. All measurements are made relative to the facility ground. A RPA is being developed in a process which involves the investigation of several prototypes. The first prototype has been tested on a thermal plasma. The knowledge gained from its development and testing were applied to the development of a RPA for collimated plasma. The prototypes consist of four equally spaced grids and an ion collector. The outermost grid is a ground. The second grid acts as a bias to repel electrons. The third is a variable v voltage ion suppressor. Grid four (inner grid) acts to repel secondary electrons, being biased equal to the first. Knowledge gained during these two stages are being applied to the development of a high temperature RPA Testing of this device involves the determination of its output parameters. sensitivity, and responses to a wide range of energies and densities. Each grid will be tested individually by changing only its voltage and observing the output from the RPA. To verify that the RPA is providing proper output. it is compared to the output from a Langmuir or Faraday probe.

Karr, Gerald R.

1997-01-01

375

Spectroscopic Measurement of Plasma in the Reactive Plasma Spray Process  

Microsoft Academic Search

Reactive RF (Radio Frequency) plasma spray process, in which metal element reacts with surrounding active species in plasma, has been receiving great interest to form nitride ceramics thick coatings. It was possible to fabricate TiN, Si3N4 and AlN thick coatings by this process. However, nitriding process has not been elucidated yet. To control the formation degree of the nitride with

Motohiro Yamada; Tatsuya Inamoto; Masahiro Fukumoto; Toshiaki Yasui

2006-01-01

376

The Diagnostics of the External Plasma for the Plasma Rocket  

NASA Technical Reports Server (NTRS)

Three regions of plasma temperature/energy are being investigated to understand fully the behavior of the plasma created by the propulsion device and the operation of the RPA. Each type of plasma has a RPA associated with it; i.e. a thermal RPA, a collimated RPA, and a high temperature RPA. Through the process of developing the thermal and collimated RPAs, the proper knowledge and experience has been gained to not only design a high temperature RPA for the plasma rocket, but to understand its operation, results, and uncertainty. After completing a literature search for, reading published papers on, and discussing the operation of the RPA with electric propulsion researchers, I applied the knowledge gained to the development of a RPA for thermal plasma. A design of a thermal RPA was made which compensates for a large Debye length and low ionized plasma. From this design a thermal RPA was constructed. It consists of an outer stainless steel casing, a phenolic insulator (outgases slightly), and stainless steel mesh for the voltage screens. From the experience and knowledge gained in the development of the thermal RPA, a RPA for collimated plasma was developed. A collimated RPA has been designed and constructed. It compensate for a smaller Debye length and much higher ionization than that existing in the thermal plasma. It is 17% of the size of the thermal RPA. A stainless steel casing shields the detector from impinging electrons and ions. An insulating material, epoxy resin, was utilized which has a negligible outgassing. This material can be molded in styrofoam and machined quite nicely. It is capable of withstanding moderately high temperatures. Attached to this resin insulator are inconel screens attached by silver plated copper wire to a voltage supply. All the work on the RPAs and thermal ion source, I performed in the University of Alabama in Huntsville's (UAH) engineering machine shop.

Karr, Gerald R.

1997-01-01

377

Pulse-discharge plasmas for plasma-accelerator applications  

SciTech Connect

For particle-beam-driven plasma wakefield accelerators, a long and fully-ionized plasma is desirable. We describe an experiment at UCLA to develop a prototype of such plasma using a pulsed-current discharge. Scaling of the plasma density with glass-tube diameter and with discharge-circuit parameters is currently underway. We have found that 4 Torr of Argon can be fully ionized to a density of about 1.3 Multiplication-Sign 10{sup 17} cm{sup -3} when the current density in the 1 inch diameter, 1.2 meter-long tube is around 2 kA/cm{sup 2}, at least at one point along the discharge. The homogeneity of the plasma density in the longitudinal direction is crucial to prevent slippage of the driven plasma structures with the particles. Equally important are the transverse gradients since any dipole asymmetry in the transverse direction can lead to 'steering' of the particle beam. The longitudinal and transverse gradients may be a function of time into the discharge, the shape of the electrodes, the tube size, and the fractional ionization for a given fill pressure. These issues are currently under investigation.

Clayton, C. E.; Joshi, C.; Lopes, N. C. [Department of Electrical Engineering, University of California at Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095 (United States); Grupo de Lasers e Plasmas, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico Av. Rovisco Pais, Lisboa 1049-001 (Portugal)

2012-12-21

378

Intermittent Heating of the Solar Corona by Heat Flux-generated Ion Cyclotron Waves  

Microsoft Academic Search

Recently, we suggested that the source of ion heating in solar coronal holes is small-scale reconnection events (microflares) at the coronal base. The microflares launch intermittent heat flux up into the corona exciting ion cyclotron waves through a plasma microinstability. The ions are heated by these waves during the microflare bursts and then evolve with no energy input between the

S. A. Markovskii; Joseph V. Hollweg

2004-01-01

379

Platelet-Rich Plasma  

PubMed Central

Context: Platelet-rich plasma (PRP) may affect soft tissue healing via growth factors released after platelet degranulation. Because of this potential benefit, clinicians have begun to inject PRP for the treatment of tendon, ligament, muscle, and cartilage injuries and early osteoarthritis. Evidence Acquisition: A PubMed search was performed for studies relating to PRP, growth factors, and soft tissue injuries from 1990 to 2010. Relevant references from these studies were also retrieved. Results: Soft tissue injury is a major source of disability that may often be complicated by prolonged and incomplete recovery. Numerous growth factors may potentiate the healing and regeneration of tendons and ligaments. The potential benefits of biologically enhanced healing processes have led to a recent interest in the use of PRP in orthopaedic sports medicine. There has been widespread anecdotal use of PRP for muscle strains, tendinopathy, and ligament injuries and as a surgical adjuvant to rotator cuff repair, anterior cruciate ligament reconstruction, and meniscal or labral repairs. Although the fascination with this emerging technology has led to a dramatic increase in its use, scientific data supporting this use are still in their infancy. Conclusions: The literature is replete with studies on the basic science of growth factors and their relation to the maintenance, proliferation, and regeneration of various tissues and tissue-derived cells. Despite the promising results of several animal studies, well-controlled human studies are lacking. PMID:23015939

Cole, Brian J.; Seroyer, Shane T.; Filardo, Giuseppe; Bajaj, Sarvottam; Fortier, Lisa A.

2010-01-01

380

Compact plasma accelerator  

NASA Technical Reports Server (NTRS)

A compact plasma accelerator having components including a cathode electron source, an anodic ionizing gas source, and a magnetic field that is cusped. The components are held by an electrically insulating body having a central axis, a top axial end, and a bottom axial end. The cusped magnetic field is formed by a cylindrical magnet having an axis of rotation that is the same as the axis of rotation of the insulating body, and magnetized with opposite poles at its two axial ends; and an annular magnet coaxially surrounding the cylindrical magnet, magnetized with opposite poles at its two axial ends such that a top axial end has a magnetic polarity that is opposite to the magnetic polarity of a top axial end of the cylindrical magnet. The ionizing gas source is a tubular plenum that has been curved into a substantially annular shape, positioned above the top axial end of the annular magnet such that the plenum is centered in a ring-shaped cusp of the magnetic field generated by the magnets. The plenum has one or more capillary-like orifices spaced around its top such that an ionizing gas supplied through the plenum is sprayed through the one or more orifices. The plenum is electrically conductive and is positively charged relative to the cathode electron source such that the plenum functions as the anode; and the cathode is positioned above and radially outward relative to the plenum.

Foster, John E. (Inventor)

2004-01-01

381

Welding arc plasma physics  

NASA Technical Reports Server (NTRS)

The problems of weld quality control and weld process dependability continue to be relevant issues in modern metal welding technology. These become especially important for NASA missions which may require the assembly or repair of larger orbiting platforms using automatic welding techniques. To extend present welding technologies for such applications, NASA/MSFC's Materials and Processes Lab is developing physical models of the arc welding process with the goal of providing both a basis for improved design of weld control systems, and a better understanding of how arc welding variables influence final weld properties. The physics of the plasma arc discharge is reasonably well established in terms of transport processes occurring in the arc column itself, although recourse to sophisticated numerical treatments is normally required to obtain quantitative results. Unfortunately the rigor of these numerical computations often obscures the physics of the underlying model due to its inherent complexity. In contrast, this work has focused on a relatively simple physical model of the arc discharge to describe the gross features observed in welding arcs. Emphasis was placed of deriving analytic expressions for the voltage along the arc axis as a function of known or measurable arc parameters. The model retains the essential physics for a straight polarity, diffusion dominated free burning arc in argon, with major simplifications of collisionless sheaths and simple energy balances at the electrodes.

Cain, Bruce L.

1990-01-01

382

Space Plasma Physics  

NASA Technical Reports Server (NTRS)

Dr. James L. Horwitz and R. Hugh Comfort's studies with the high altitude TIDE data have been progressing well. We concluded a study on the relationship of polar cap ion properties observed by TIDE near apogee with solar wind and IMF conditions. We found that in general H+ did not correlate as well as O+ with solar wind and IMF parameters. O+ density correlated(sub IMF), and Kp. At lower solar wind speeds, O+ density decreased with increasing latitude, but this trend was not observed at higher solar wind speeds. By comparing these results with results from other studies of O+ in different parts of the magnetosphere, we concluded that O+ ions often leave the ionosphere near the foot point of the cusp/cleft region, pass through the high-altitude polar cap lobes, and eventually arrive in the plasma sheet. We found that H+ outflows are a persistent feature of the polar cap and are not as dependent on the geophysical conditions; even classical polar wind models show H+ ions readily escaping owing to their low mass. Minor correlations with solar wind drivers were found; specifically, H+ density correlated best with IMF By, V(sub sw)B(sub IMF), and ESW(sub sw).

Wu, S. T.

2000-01-01

383

Criticality in Plasma Membranes  

NASA Astrophysics Data System (ADS)

Recent work in giant plasma membrane vesicles (GPMVs) isolated from living cells demonstrated that they can be tuned with a single parameter (temperature) to criticality, not far from in vivo temperatures [1,2]. Criticality requires the fine-tuning of two parameters suggesting important biological function, and its presence resolves many of the paradoxes associated with putative lipid rafts. Here we present a minimal model of membrane inhomogeneities. We incorporate criticality using a conserved order parameter Ising model coupled to a simple actin cytoskeleton interacting through fields which act as point-like pinning sites. Using this model we make a host of experimentally testable predictions that are in line with recent published findings. At physiological temperatures we find inhomogeneities in the form of critical fluctuations with a length scale of roughly 20nm. Individual constituents making up these liquid domains are mobile, though they diffuse anomalously, but the correlated regions themselves can last as long as the cytoskeleton persists. We explain this by considering the effective long ranged interaction mediated by the Ising order parameter. In general we find Ising criticality organizes and spatially segregates membrane components by providing a channel for interaction over large distances. [1] Veatch et al., ACS Chem Biol. 2008 3(5):287-93 [2] Honerkamp-Smith, Veatch, and Keller, Biochim Biophys Acta. 2008 (in press)

Machta, Ben; Sethna, James; Veatch, Sarah; Papanikolaou, Stefanos

2010-03-01

384

Laser plasma thruster  

NASA Astrophysics Data System (ADS)

The laser plasma thruster (LPT) is a new microthruster for small satellites. We report on development and testing of a prototype LPT. Some advantages of the LPT are: thruster voltage 4 V, mass less than 1 kg, power-to-thrust ratio 10 kW/N, and Isp up to 1000 s. Typical thrust level is 250 ?N with PVC fuel. Thrust of 1 mN is expected with energetic fuel. The pre-prototype continuous-thrust experiment includes the laser mount and heat sink, lens mounts, and focusing mechanism, which are coupled to the target-material transport mechanism. The target material is applied to a transparent plastic tape, and the laser is focused on a series of tracks on the tape. The tape-drive hardware and laser-drive electronics are described. Design, construction, and calibration of the thrust stand are described. During continuous operation, the exhaust plume is deflected in the direction of the moving tape. When the laser is operated in pulsed mode, the exhaust plume is perpendicular to the tape (parallel to the optical axis). This provides some thrust-vector control. Measured thrust is 70 ?N with PVC fuel, and 550 ?N with energetic fuel, with a specific impulse of 350 s.

Luke, J. R.; Phipps, C. R.; McDuff, G. G.

385

Hall Effect in a Plasma.  

ERIC Educational Resources Information Center

Describes an apparatus and procedure for conducting an undergraduate laboratory experiment to quantitatively study the Hall effect in a plasma. Includes background information on the Hall effect and rationale for conducting the experiment. (JN)

Kunkel, W. B.

1981-01-01

386

Spurting Plasma on the Sun  

NASA Video Gallery

This video from NASA's Solar Dynamics Observatory spacecraft, orbiting more than 20,000 miles above Earth, shows a stream of plasma burst out from the sun on May 27,2014. Since the stream lacked en...

387

Plasma transport near material boundaries  

SciTech Connect

The fluid theory of two-dimensional (2-d) plasma transport in axisymmetric devices is reviewed. The forces which produce flow across the magnetic field in a collisional plasma are described. These flows may lead to up-down asymmetries in the poloidal rotation and radial fluxes. Emphasis is placed on understanding the conditions under which the known 2-d plasma fluid equations provide a valid description of these processes. Attempts to extend the fluid treatment to less collisional, turbulent plasmas are discussed. A reduction to the 1-d fluid equations used in many computer simulations is possible when sources or boundary conditions provide a large enough radial scale length. The complete 1-d fluid equations are given in the text, and 2-d fluid equations are given in the Appendix.

Singer, C.E.

1985-06-01

388

Space Flight Plasma Data Analysis  

NASA Technical Reports Server (NTRS)

This slide presentation reviews a method to analyze the plasma data that is reported on board the International Space station (ISS). The Floating Potential Measurement Unit (FPMU), the role of which is to obtain floating potential and ionosphere plasma measurements for validation of the ISS charging model, assess photo voltaic array variability and interpreting IRI predictions, is composed of four probes: Floating Potential Probe (FPP), Wide-sweep Langmuir Probe (WLP), Narrow-sweep Langmuir Probe (NLP) and the Plasma Impedance Probe (PIP). This gives redundant measurements of each parameter. There are also many 'boxes' that the data must pass through before being captured by the ground station, which leads to telemetry noise. Methods of analysis for the various signals from the different sets are reviewed. There is also a brief discussion of LP analysis of Low Earth Orbit plasma simulation source.

Wright, Kenneth H.; Minow, Joseph I.

2009-01-01

389

Plasma fluoride and enamel fluorosis.  

PubMed

It is postulated that tissue fluid F concentrations are the primary determinants of flouride effects on bones and developing teeth and that these concentrations are dependent on, or mirrored by, blood plasma F. It has earlier been shown that the plasma F levels are dependent on the dietary F supply as well as on skeletal F concentration. Fasting and post-ingestion or postinjection plasma F levels have been determined in rats on F doses that cause different degrees of enamel fluorosis. The results indicate that temporary peak values rather than elevated fasting values are responsible for the occurrence of enamel fluorosis and that the peak values must approach about 10 muM in order to block enamel formation by the ameloblasts. The diagnostic and prognostic importance of plasma F determinations is discussed. PMID:1000344

Angmar-Månsson, B; Ericsson, Y; Ekberg, O

1976-11-24

390

A Plasma Flame Spray Handbook.  

National Technical Information Service (NTIS)

The Plasma Spraying process is a versatile fabrication technique used to apply a wide range of coatings on various workpiece materials. Coatings are applied to restore or attain desired dimensions, to provide electrical or thermal shielding or conduction,...

T. J. Roseberry, F. W. Boulger

1977-01-01

391

Laser Assisted Plasma Arc Welding  

SciTech Connect

Experiments have been performed using a coaxial end-effecter to combine a focused laser beam and a plasma arc. The device employs a hollow tungsten electrode, a focusing lens, and conventional plasma arc torch nozzles to co-locate the focused beam and arc on the workpiece. Plasma arc nozzles were selected to protect the electrode from laser generated metal vapor. The project goal is to develop an improved fusion welding process that exhibits both absorption robustness and deep penetration for small scale (< 1.5 mm thickness) applications. On aluminum alloys 6061 and 6111, the hybrid process has been shown to eliminate hot cracking in the fusion zone. Fusion zone dimensions for both stainless steel and aluminum were found to be wider than characteristic laser welds, and deeper than characteristic plasma arc welds.

FUERSCHBACH,PHILLIP W.

1999-10-05

392

Industrial applications for plasma torches  

NASA Astrophysics Data System (ADS)

The first generation plasma torch for industrial applications developed at Aerospatial has two coaxial tubular electrodes jointed by a chamber for turbulent gas injection. The design theory, basic principles, functions, servomechanisms, operations, and maintainability are listed. Drawings are included.

Allard, A.

1983-11-01

393

Industrial applications for plasma torches  

Microsoft Academic Search

The first generation plasma torch for industrial applications developed at Aerospatial has two coaxial tubular electrodes jointed by a chamber for turbulent gas injection. The design theory, basic principles, functions, servomechanisms, operations, and maintainability are listed. Drawings are included.

A. Allard

1983-01-01

394

Plasma reactor waste management systems  

NASA Technical Reports Server (NTRS)

The University of North Dakota is developing a plasma reactor system for use in closed-loop processing that includes biological, materials, manufacturing, and waste processing. Direct-current, high-frequency, or microwave discharges will be used to produce plasmas for the treatment of materials. The plasma reactors offer several advantages over other systems, including low operating temperatures, low operating pressures, mechanical simplicity, and relatively safe operation. Human fecal material, sunflowers, oats, soybeans, and plastic were oxidized in a batch plasma reactor. Over 98 percent of the organic material was converted to gaseous products. The solids were then analyzed and a large amount of water and acid-soluble materials were detected. These materials could possibly be used as nutrients for biological systems.

Ness, Robert O., Jr.; Rindt, John R.; Ness, Sumitra R.

1992-01-01

395

Plasma Chemistry and Plasma Processing, Vol. 23, No. 1, March 2003 ( 2003) Model of the Negative DC Corona Plasma  

E-print Network

Plasma Chemistry and Plasma Processing, Vol. 23, No. 1, March 2003 ( 2003) Model of the Negative DC Corona Plasma: Comparison to the Positive DC Corona Plasma Junhong Chen1 and Jane H. Davidson1,2 Receiûed March 26, 2002, reûised June 14, 2002 A numerical model of the negatiûe DC corona plasma along a thin

Chen, Junhong

396

Plasma Physics. Basic Theory with Fusion Applications  

Microsoft Academic Search

Plasma Physics - Basic Theory with Fusion Applications presents a thorough treatment of plasma physics, beginning at an introductory level and including an extensive discussion of its applications in thermonuclear fusion research. The physics of fusion plasmas is explained mainly in relation to recent progress in tokamak research, but other plasma confinement schemes, such as stellarators and inertial confinement, are

Kyoji Nishikawa; Masahiro Wakatani

1994-01-01

397

PREFACE: 1982 International Conference on Plasma Physics  

Microsoft Academic Search

Invited Papers: The Physics of Hot Plasmas During the last decade a dramatic evolution of plasma physics has occurred. Not only have gigantic fusion plasma machines been planned, and are now being built, and elaborate spaceships and antenna systems been constructed to explore remote parts of the cosmos; new observations have revealed fascinating structures in space, ranging from pulsar plasmas

Hans Wilhelmsson

1982-01-01

398

SYLLABUS: PHYSICS 8120 PLASMA PHYSICS FALL 2007  

E-print Network

SYLLABUS: PHYSICS 8120 PLASMA PHYSICS FALL 2007 Instructor: Prof. Paul J. Wiita Class Timings time. Required Text: Russell M. Kulsrud, Plasma Physics for Astrophysics (Princeton University Press A. Sturrock, Plasma Physics 3) Nicholas A. Krall & Alvin W. Trivelpiece, Principles of Plasma

Wiita, Paul J.

399

H IGHLIGHTS PRINCETON PLASMA PHYSICS LABORATORY  

E-print Network

H IGHLIGHTS PRINCETON PLASMA PHYSICS LABORATORY Princeton Plasma Physics Laboratory Fiscal Year 1996 #12; This publication highlights activities at the Princeton Plasma Physics Laboratory for fiscal. Park. 2 #12; Vision Statement Mission Statement The primary mission of the Princeton Plasma Physics

400

Observations on a Fully Ionized Barium Plasma  

Microsoft Academic Search

A series of spectroscopic measurements in a fully ionized barium plasma column is described and discussed. The plasma was generated in the Q-1 device in a manner similar to that used to make alkali-metal plasmas. The observations show that the density contours and the temperature profiles in the body of the plasma were strongly influenced by conditions at the end

N. Rynn; E. Hinnov; L. C. Johnson

1965-01-01

401

DENSITY LIMITS IN TOROIDAL PLASMAS MARTIN GREENWALD  

E-print Network

DENSITY LIMITS IN TOROIDAL PLASMAS MARTIN GREENWALD MIT - PLASMA SCIENCE & FUSION CENTER Presented on plasma pressure, current, and density · Understanding these limits and their implications has always been an active area of research #12;DENSITY LIMITS - AN IMPORTANT ISSUE FOR MAGNETIC FUSION · 2 DTR n v · Plasma

Greenwald, Martin

402

The efficiency of an explosive plasma compressor  

Microsoft Academic Search

The paper presents results of an experimental investigation of the efficiency of an explosive plasma compressor. The experimental set-up consisted of the explosive plasma compressor and a calorimeter. The detonation of an explosive charge produced a shock wave which compressed the working gas and converted it into a plasma. The plasma was thrust by the explosion into a steel calorimetric

A. E. Voitenko; V. I. Kirko

1975-01-01

403

Nano-Fabrication by Cathodic Plasma Electrolysis  

Microsoft Academic Search

Cathodic plasma electrolytic (CPE) techniques are new groups of coating processes, which can be used for fabrication of nanostructured layers on surface of a wide range of metallic substrates. The most exciting visible feature of these atmospheric-based plasma techniques is continuous sparking on processed surface inside an electrolyte. Unlike the anodic part of plasma electrolysis (usually known as plasma electrolytic

M. Aliofkhazraei; A. Sabour Rouhaghdam; P. Gupta

2011-01-01

404

Computing in plasma physics and astrophysics  

Microsoft Academic Search

The present volume contains extended abstracts of conference contributions dealing with computational aspects of plasma physics and astrophysics. The general subjects encompass stellar evolution and pulsars, particle simulation in plasmas and stellar systems, MHD equilibrium and stability, nonlinear MHD behavior of plasmas, transport in laboratory plasmas, and transport in stars. Specific topics include the hydrodynamics of the helium flash, gravitational

D. Biskamp

1976-01-01

405

Plasma Measurements in A Levitated Pulsed Octupole  

E-print Network

V are produced by a coaxial gun. Cold ion plasmas are produced in the field by electron cyclotron resonance #12;For the hot ion, gun injected plasma and for the cold ion, microwave plasma, the density decayPlasma Measurements in A Levitated Pulsed Octupole by H.K. Forsen, D.W. Kerst, R.A. Breun, A

Sprott, Julien Clinton

406

Electron Plasma Orbits from Competing Diocotron Drifts  

NASA Astrophysics Data System (ADS)

The perpendicular dynamics of a pure electron plasma column are investigated when the plasma spans two Penning-Malmberg traps with noncoinciding axes. The plasma executes noncircular orbits described by competing image-charge electric-field (diocotron) drifts from the two traps. A simple model is presented that predicts a set of nested orbits in agreement with observed plasma trajectories.

Hurst, N. C.; Danielson, J. R.; Baker, C. J.; Surko, C. M.

2014-07-01

407

Absorption imaging of ultracold neutral plasmas  

Microsoft Academic Search

We report optical absorption imaging of ultracold neutral plasmas. Imaging allows direct observation of the ion density profile and expansion of the plasma. The frequency dependence of the plasma's optical depth gives the ion absorption spectrum, which is broadened by the ion motion. We use the spectral width to monitor ion equilibration in the first 250 ns after plasma formation.

C. E. Simien; Y. C. Chen; P. Gupta; S. Laha; Y. N. Martinez; P. G. Mickelson; S. B. Nagel; T. C. Killian

2005-01-01

408

ISRAELI PLASMA SCIENCE AND TECHNOLOGY ASSOCIATION  

E-print Network

#12;ISRAELI PLASMA SCIENCE AND TECHNOLOGY ASSOCIATION 15th ISRAELI CONFERENCE ON PLASMA SCIENCE AND APPLICATIONS H.I.T. ­ Holon Institute of Technology February 4th, 2013 BOOK OF ABSTRACTS http://plasma annual conference of the Israeli Plasma Science and Technology Association (IPSTA). This is the second

409

TOPICAL REVIEW: Thermal plasma waste treatment  

Microsoft Academic Search

Plasma waste treatment has over the past decade become a more prominent technology because of the increasing problems with waste disposal and because of the realization of opportunities to generate valuable co-products. Plasma vitrification of hazardous slags has been a commercial technology for several years, and volume reduction of hazardous wastes using plasma processes is increasingly being used. Plasma gasification

Joachim Heberlein; Anthony B. Murphy

2008-01-01

410

The physics of laser plasma interactions  

Microsoft Academic Search

Contents, abridged: Computer simulation of plasmas using particle codes. Propagation of obliquely incident light waves. Collisional absorption of electromagnetic waves in plasmas. Parametric excitation of electron and ion waves. Stimulated Raman scattering. Stimulated Brillouin scattering. Heating by plasma waves. Laser plasma experiments.

William L. Kruer

1988-01-01

411

Plasma waves in the Jovian magnetosphere  

Microsoft Academic Search

Any waves which are influenced by the presence of a plasma are called plasma waves. In general, plasma waves can be classified as either electromagnetic, which have both electric and magnetic fields, or electrostatic, which have no magnetic field. The recent Voyager encounters provide the basis for the first comprehensive investigation of plasma waves in the magnetosphere of Jupiter. The

D. A. Gurnett; F. L. Scarf

1983-01-01

412

Control of the thermionic vacuum arc plasma  

Microsoft Academic Search

The aim of this paper is to investigate the properties of thermionic vacuum arc (TVA) plasma and to optimize the discharge parameters in order to obtain plasma with high energetic ions and high ionization degree. Using emissive probe technique, the spatial plasma potential distribution has been measured. Experimental results show that the spatial distribution of plasma potential strongly depends on

V. Tiron; G. Popa

2010-01-01

413

How a Plasma Etcher Works  

NSDL National Science Digital Library

This website includes an animation which illustrates how a Plasma Etcher works. Objective: Describe all the steps used to load, etch, and unload a wafer from a plasma etcher. This simulation is from Module 048 of the Process & Equipment II Cluster of the MATEC Module Library (MML). You can find this animation under the section "Process & Equipment II." To view other clusters or for more information about the MML visit http://matec.org/ps/library3/process_I.shtmlKey

2012-11-19

414

Flavors in an expanding plasma  

E-print Network

We consider the effect of an expanding plasma on probe matter by determining time-dependent D7 embeddings in the holographic dual of an expanding viscous plasma. We calculate the chiral condensate and meson spectra including contributions of viscosity. The chiral condensate essentially confirms the expectation from the static black hole. For the meson spectra we propose a scheme that is in agreement with the adiabatic approximation. New contributions arise for the vector mesons at the order of the viscosity terms.

Johannes Große; Romuald A. Janik; Piotr Surówka

2007-09-25

415

Neutrino dispersion in magnetized plasma  

E-print Network

The neutrino dispersion in the charge symmetric magnetized plasma is investigated. We have studied the plasma contribution into the additional energy of neutrino and obtained the simple expression for it. We consider in detail the neutrino self-energy under physical conditions of weak field, moderate field and strong field limits. It is shown that our result for neutrino dispersion in moderate magnetic field differ substantially from the previous one in the literature.

N. V. Mikheev; E. N. Narynskaya

2008-12-02

416

Flashboard plasma characterization using spectroscopy  

Microsoft Academic Search

The plasma produced by a 10 cm×6 cm planar flashboard has been investigated by emission spectroscopy. The plasma composition, density, and temperature have been determined with time and space resolution using measurement of the relative intensity of spontaneous emission in different atomic and ionic transitions together with calculations based on a collisional-radiative equilibrium model. The (1-2)×1013 cm-3 and (3-4) eV

Andrei Ben-Amar Baranga; Niansheng Qi; David A. Hammer

1992-01-01

417

Fusion Plasma Theory project summaries  

SciTech Connect

This Project Summary book is a published compilation consisting of short descriptions of each project supported by the Fusion Plasma Theory and Computing Group of the Advanced Physics and Technology Division of the Department of Energy, Office of Fusion Energy. The summaries contained in this volume were written by the individual contractors with minimal editing by the Office of Fusion Energy. Previous summaries were published in February of 1982 and December of 1987. The Plasma Theory program is responsible for the development of concepts and models that describe and predict the behavior of a magnetically confined plasma. Emphasis is given to the modelling and understanding of the processes controlling transport of energy and particles in a toroidal plasma and supporting the design of the International Thermonuclear Experimental Reactor (ITER). A tokamak transport initiative was begun in 1989 to improve understanding of how energy and particles are lost from the plasma by mechanisms that transport them across field lines. The Plasma Theory program has actively-participated in this initiative. Recently, increased attention has been given to issues of importance to the proposed Tokamak Physics Experiment (TPX). Particular attention has been paid to containment and thermalization of fast alpha particles produced in a burning fusion plasma as well as control of sawteeth, current drive, impurity control, and design of improved auxiliary heating. In addition, general models of plasma behavior are developed from physics features common to different confinement geometries. This work uses both analytical and numerical techniques. The Fusion Theory program supports research projects at US government laboratories, universities and industrial contractors. Its support of theoretical work at universities contributes to the office of Fusion Energy mission of training scientific manpower for the US Fusion Energy Program.

Not Available

1993-10-01

418

Plasma processes and emission spectra in laser induced plasmas: A point of view  

NASA Astrophysics Data System (ADS)

In this paper emission spectra of the plasma produced by laser-matter interaction are discussed in terms of the correlation between the elementary plasma processes and the evolution of plasma parameters during the expansion. Three main stages have been identified and discussed in details: high density plasma, near equilibrium plasma and non-equilibrium plasma including molecular formation. In order to develop a comprehensive point of view on the correlation between plasma mechanisms and spectral emission features several concepts already discussed and elucidated in the plasma science have been adapted to the description of the laser induced plasma and to its ionizing and recombining character.

De Giacomo, A.; Dell'Aglio, M.; De Pascale, O.; Gaudiuso, R.; Palleschi, V.; Parigger, C.; Woods, A.

2014-10-01

419

Ionosphere-magnetosphere coupling. I - Thermal plasma  

NASA Technical Reports Server (NTRS)

The complex interaction of the cold plasma of the plasmasphere and ionosphere with the hot plasma of the ring current and the plasma sheet is studied. It is seen that a coupling, probably through wave particle interactions, exists which seems to have a strong influence on the temperature of the plasma of the outer plasmasphere and on the detailed dynamics of the bulge region, especially the formation of detached plasma regions or plasma tails. Also, there is evidence that the outer plasmasphere may display very high temperatures, and that detached plasma regions are closely associated with ring current injections.

Chappell, C. R.

1975-01-01

420

Characterisation of plasma in a rail gun  

NASA Technical Reports Server (NTRS)

The mechanism of plasma and projectile acceleration in a DC rail gun is described from a microscopic point of view through the establishment of the Hall field. The plasma conductivity is shown to be a tensor, indicating that there is a small component of current parallel to the direction of acceleration. The plasma characteristics are evaluated in the experiment of Bauer et. al., as a function of plasma mass through a simple fluid mechanical analysis of the plasma. By equating the energy dissipatated in the plasma with the radiation heat loss, the properties of the plasma are determined.

Ray, P. K.

1986-01-01

421

BOOK REVIEW: Kinetic theory of plasma waves, homogeneous plasmas  

NASA Astrophysics Data System (ADS)

The linear theory of plasma waves in homogeneous plasma is arguably the most mature and best understood branch of plasma physics. Given the recently revised version of Stix's excellent Waves in Plasmas (1992), one might ask whether another book on this subject is necessary only a few years later. The answer lies in the scope of this volume; it is somewhat more detailed in certain topics than, and complementary in many fusion research relevant areas to, Stix's book. (I am restricting these comments to the homogeneous plasma theory only, since the author promises a second volume on wave propagation in inhomogeneous plasmas.) This book is also much more of a theorist's approach to waves in plasmas, with the aim of developing the subject within the logical framework of kinetic theory. This may indeed be pleasing to the expert and to the specialist, but may be too difficult to the graduate student as an `introduction' to the subject (which the author explicitly states in the Preface). On the other hand, it may be entirely appropriate for a second course on plasma waves, after the student has mastered fluid theory and an introductory kinetic treatment of waves in a hot magnetized `Vlasov' plasma. For teaching purposes, my personal preference is to review the cold plasma wave treatment using the unified Stix formalism and notation (which the author wisely adopts in the present book, but only in Chapter 5). Such an approach allows one to deal with CMA diagrams early on, as well as to provide a framework to discuss electromagnetic wave propagation and accessibility in inhomogeneous plasmas (for which the cold plasma wave treatment is perfectly adequate). Such an approach does lack some of the rigour, however, that the author achieves with the present approach. As the author correctly shows, the fluid theory treatment of waves follows logically from kinetic theory in the cold plasma limit. I only question the pedagogical value of this approach. Otherwise, I welcome this addition to the literature, for it gives the teacher of the subject a valuable reference where the inquisitive student will be able to read up on and satisfy himself about the practicality and reliability of the Vlasov theory in a hot magnetized and collisionless plasma. The book has excellent treatments of several new topics not included in previous textbooks, for example, the relativistic theory of plasma wave propagation, so important in electron cyclotron heating of magnetically confined fusion plasmas, a discussion of current drive theory and there is a welcome introduction to parametric instabilities in the final chapter. There are some things that make the readability of the book somewhat difficult. In the early parts, certain advanced concepts are introduced without much motivation or explanation, although the author is trying to be helpful by providing a list of relevant references at the end of each chapter. Here the teacher's role will be critical. Again, a certain amount of previous knowledge of the subject would prove to be invaluable to the student. The main content of the book is included in 11 chapters. Use is made of CGS Gaussian units, a favourite of plasma theorists. As the author states, these are still widely used in advanced plasma theory, and the student is well advised to become familiar with this system of units (as well as the SI system for applications). To help the reader in the Introduction, the author defines various expressions often used in plasma physics in practical units (frequencies in hertz, lengths in centimetres, temperatures in kiloelectronvolts and magnetic fields in teslas). Chapter 2 is entitled `Plasma Electrodynamics' and it introduces the Maxwell-Vlasov set of equations, as well as the important fundamentals of wave propagation, such as polarization, dispersion and the dielectric tensor, and energy relations. In Chapter 3, `Elementary Plasma Kinetic Theory', the author derives the Vlasov equation and the Fokker-Planck equation from the BBGKY hierarchy. This is a somewhat unusual chapter in a book on plasma waves, but I

Porkolab, Miklos

1998-11-01

422

Electric field divertor plasma pump  

DOEpatents

An electric field plasma pump includes a toroidal ring bias electrode positioned near the divertor strike point of a poloidal divertor of a tokamak, or similar plasma-confining apparatus. For optimum plasma pumping, the separatrix of the poloidal divertor contacts the ring electrode, which then also acts as a divertor plate. A plenum or other duct near the electrode includes an entrance aperture open to receive electrically-driven plasma. The electrode is insulated laterally with insulators, one of which is positioned opposite the electrode at the entrance aperture. An electric field E is established between the ring electrode and a vacuum vessel wall, with the polarity of the bias applied to the electrode being relative to the vessel wall selected such that the resultant electric field E interacts with the magnetic field B already existing in the tokamak to create an E [times] B/B[sup 2] drift velocity that drives plasma into the entrance aperture. The pumped plasma flow into the entrance aperture is insensitive to variations, intentional or otherwise, of the pump and divertor geometry. Pressure buildups in the plenum or duct connected to the entrance aperture in excess of 10 mtorr are achievable. 11 figs.

Schaffer, M.J.

1994-10-04

423

Electric field divertor plasma pump  

DOEpatents

An electric field plasma pump includes a toroidal ring bias electrode (56) positioned near the divertor strike point of a poloidal divertor of a tokamak (20), or similar plasma-confining apparatus. For optimum plasma pumping, the separatrix (40) of the poloidal divertor contacts the ring electrode (56), which then also acts as a divertor plate. A plenum (54) or other duct near the electrode (56) includes an entrance aperture open to receive electrically-driven plasma. The electrode (56) is insulated laterally with insulators (63,64), one of which (64) is positioned opposite the electrode at the entrance aperture. An electric field E is established between the ring electrode (56) and a vacuum vessel wall (22), with the polarity of the bias applied to the electrode being relative to the vessel wall selected such that the resultant electric field E interacts with the magnetic field B already existing in the tokamak to create an E.times.B/B.sup.2 drift velocity that drives plasma into the entrance aperture. The pumped plasma flow into the entrance aperture is insensitive to variations, intentional or otherwise, of the pump and divertor geometry. Pressure buildups in the plenum or duct connected to the entrance aperture in excess of 10 mtorr are achievable.

Schaffer, Michael J. (San Diego, CA)

1994-01-01

424

Sheet shaped plasma production using microwave-plasma interaction with ECR region  

Microsoft Academic Search

Summary form only given. To control the shape of high density plasma has been one of the issues for the application of plasma to industrial usages. Therefore, ECR plasma is a good candidate of a high density plasma. A sheet shaped high density plasma could be used to modify the surface of materials uniformly and as the basis for electron

M. Yoshida; K. Kajinishi

2002-01-01

425

CHAPTER 5. PLASMA DESCRIPTIONS I: KINETIC, TWO-FLUID 1 Plasma Descriptions I  

E-print Network

CHAPTER 5. PLASMA DESCRIPTIONS I: KINETIC, TWO-FLUID 1 Chapter 5 Plasma Descriptions I: Kinetic, Two-Fluid Descriptions of plasmas are obtained from extensions of the kinetic theory of gases of charged particles in the plasma, and because the electric and magnetic fields in the plasma must

Callen, James D.

426

Process control of a plasma treatment of wool by plasma diagnostics  

Microsoft Academic Search

Wool was treated in a large-volume microwave plasma source SLAN II [D. Korzec, F. Werner, R. Winter, J. Engemann, Scaling of microwave slot antenna (SLAN): a concept for efficient plasma generation. Plasma Sources Sci. Technol. 5 (1996) 216–234] to improve the felting tendency. To control this plasma process, the applicability of three plasma diagnostic methods, optical emission spectroscopy (OES), double

F. Osenberg; D. Theirich; A. Decker; J. Engemann

1999-01-01

427

A Short Introduction to Plasma Physics  

E-print Network

This chapter contains a short discussion of some fundamental plasma phenomena. In section 2 we introduce key plasma properties like quasi-neutrality, shielding, particle transport processes and sheath formation. In section 3 we describe the simplest plasma models: collective phenomena (drifts) deduced from single-particle trajectories and fundamentals of plasma fluid dynamics. The last section discusses wave phenomena in homogeneous, unbounded, cold plasma.

Wiesemann, K

2013-01-01

428

ATMOSPHERIC-PRESSURE PLASMA PROCESS AND APPLICATIONS  

Microsoft Academic Search

This paper provides a general discussion of atmospheric-pressure plasma generation, processes, and applications. There are two distinct categories of atmospheric-pressure plasmas: thermal and nonthermal. Thermal atmospheric-pressure plasmas include those produced in high intensity arcs, plasma torches, or in high intensity, high frequency discharges. Although nonthermal plasmas are at room temperatures, they are extremely effective in producing activated species, e.g., free

Peter Kong

429

Maxwell Prize Session: Hot Plasma Effects in Gas Discharge Plasma  

NASA Astrophysics Data System (ADS)

Radio frequency (rf) gas discharges have been known for over a century. Recently, interest in low-pressure rf discharges has been revitalized due to great achievements and expectations in using such devices in plasma processing for manufacturing of semiconductor chips and lighting technology. In rf discharges the dominant interaction of the electromagnetic field with the plasma, and thus rf power absorption, takes place in the plasma boundary layer (near the electrode sheath in a capacitive and in the skin layer in an inductive rf discharge). The interaction of the electromagnetic field with plasma can be of local or nonlocal character. In the first case, there is local coupling between the rf current and the electric field described by a local complex conductivity tensor of a cold plasma. That corresponds to traditional (collisional) gas discharge physics. In the second case, electron thermal motion brings spatial dispersion into the relation between the rf current and the electric field, so that the conductivity tensor becomes a nonlocal operator. Stochastic (collisionless) electron heating, anomalous skin effect and a variety of plasma kinetic and nonlinear effects are typical for low-pressure rf discharges operating in the regime of nonlocal electrodynamics. Such phenomena are characteristic of hot fusion and space plasmas, where they are usually observed experimentally as some global effects. The ability to reproduce these phenomena in a table-top rf discharge experiment (equipped with spatially resolved electron kinetic and electromagnetic field diagnostics) makes the rf discharge a unique playground for basic plasma studies highly amenable to theoretical analysis. The subject of this talk is a review of nonlocal and nonlinear effects found in rf discharge experiments and theoretical analysis, where the interaction of electromagnetic field with plasma is controlled by the electron thermal motion rather than the electron-atom collisions. New features in the electron energy distribution, wave phase bifurcation and phase velocity reversal, collisionless and negative power absorption, harmonic generation and ponderomotive effect are found in these experiments and interpreted in terms of non-local, hot electron electrodynamics.

Godyak, Valery

2004-11-01

430

Characteristics of plasma properties in an ablative pulsed plasma thruster  

SciTech Connect

Pulsed plasma thrusters are electric space propulsion devices which create a highly transient plasma bulk in a short-time arc discharge that is expelled to create thrust. The transitional character and the dependency on the discharge properties are yet to be elucidated. In this study, optical emission spectroscopy and Mach-Zehnder interferometry are applied to investigate the plasma properties in variation of time, space, and discharge energy. Electron temperature, electron density, and Knudsen numbers are derived for the plasma bulk and discussed. Temperatures were found to be in the order of 1.7 to 3.1 eV, whereas electron densities showed maximum values of more than 10{sup 17} cm{sup -3}. Both values showed strong dependency on the discharge voltage and were typically higher closer to the electrodes. Capacitance and time showed less influence. Knudsen numbers were derived to be in the order of 10{sup -3}-10{sup -2}, thus, indicating a continuum flow behavior in the main plasma bulk.

Schoenherr, Tony; Nees, Frank; Arakawa, Yoshihiro [Department of Aeronautics and Astronautics, University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); Komurasaki, Kimiya [Department of Advanced Energy, University of Tokyo, Kashiwa, Chiba 277-8561 (Japan); Herdrich, Georg [Institute of Space Systems (IRS), University of Stuttgart, 70569 Stuttgart, Baden-Wuerttemberg (Germany)

2013-03-15

431

ECR Plasma Sterilisation, Argon and Nitrogen Treated Plasma  

NASA Astrophysics Data System (ADS)

ECR type plasma system was built to produce plasma in axial direction. Plasma was initiated in a specially designed Nickel - Chrome cylindrical vacuum tube which is being driven through dielectric window by 2.45GHz commercial magnetron source. Tube is also surrounded by a coil driving 150ADC to generate approximately 875Gauss magnetic field at the center. Langmuir probe and ICCD for optical spectrometry were used to characterize internal parameters like electron density, electron temperature and different characteristics of the plasma. Bacillus Subtilis var nigar, bacillus Stearothermophilus, bacillus pumilus E601, Escherichia coli and staphylococcus aureus type bacteria were selected as a reference. Each is resistant for different actions while the Bacilus cereus is the most resistant bacteria for microwave interaction. This study presents the effect of system on used bacteria. Those are gram positive and gram negative bacteria that refers to structure of cell wall. The sterilization efficacy of Argon type ECR plasma was found to be over 99, 5% in Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis (vegetative cell), Bacillus cereus (vegetative cell), Bacillus pumilus and Escherichia coli. System response type is less than 2 minutes.

Helhel, Selcuk; Oksuz, Lutfi; Cerezci, Osman; Rad, Abbas Y.

2004-09-01

432

Characteristics of plasma properties in an ablative pulsed plasma thruster  

NASA Astrophysics Data System (ADS)

Pulsed plasma thrusters are electric space propulsion devices which create a highly transient plasma bulk in a short-time arc discharge that is expelled to create thrust. The transitional character and the dependency on the discharge properties are yet to be elucidated. In this study, optical emission spectroscopy and Mach-Zehnder interferometry are applied to investigate the plasma properties in variation of time, space, and discharge energy. Electron temperature, electron density, and Knudsen numbers are derived for the plasma bulk and discussed. Temperatures were found to be in the order of 1.7 to 3.1 eV, whereas electron densities showed maximum values of more than 1017 cm-3. Both values showed strong dependency on the discharge voltage and were typically higher closer to the electrodes. Capacitance and time showed less influence. Knudsen numbers were derived to be in the order of 10-3-10-2, thus, indicating a continuum flow behavior in the main plasma bulk.

Schönherr, Tony; Nees, Frank; Arakawa, Yoshihiro; Komurasaki, Kimiya; Herdrich, Georg

2013-03-01

433

Plasma Guns for the Plasma Liner Experiment (PLX)  

NASA Astrophysics Data System (ADS)

A spherical array of minirailgun plasma accelerators is planned for the Plasma Liner Experiment (PLX) to be located at LANL. The plasma liner would be formed via merging of 30 dense, high Mach number plasma jets (n˜10^16-17 cm-3, M˜10--35, v˜50--70 km/s, rjet˜5 cm) in a spherically convergent geometry. Small parallel-plate railguns are being developed for this purpose due to their reduced system complexity and cost, with each gun planned to operate at ˜300 kA peak current, and launching up to ˜8000 ?g of high-Z plasma using a ˜50 kJ pfn. We describe experimental development of the minirailguns and their current and projected performance. Fast operating repetitive gas valves have recently been added to allow injection of high density gases including helium, argon, and (eventually) xenon. We will present the latest test results with the high-Z gases, and discuss future plans for augmenting the rails, optimizing the nozzle configuration, preionizing the injected gas, and configuring the pulse forming networks with the capacitors available to the program.

Witherspoon, F. D.; Bomgardner, R.; Case, A.; Messer, S. J.; Brockington, S.; Wu, L.; Elton, R.; Hsu, S. C.; Cassibry, J. T.; Gilmore, M. A.

2009-11-01

434

Wakes in Inertial Fusion Plasmas  

NASA Astrophysics Data System (ADS)

Plasma wave wakes, which are the collective oscillatory response near the plasma frequency to the propagation of particles or electromagnetic waves through a plasma, play a critical role in many plasma processes. New results from backwards stimulated Raman scattering (BSRS), in which wakes with phase velocities much less than the speed of light are induced by the beating of counter-propagating light waves, and from electron beam stopping, in which the wakes are produced by the motion of relativistically propagating electrons through the dense plasma, are discussed. Both processes play important roles in Inertial Confinement Fusion (ICF). In BSRS, laser light is scattered backwards out of the plasma, decreasing the energy available to compress the ICF capsule and affecting the symmetry of where the laser energy hits the hohlraum wall in indirect drive ICF. The plasma wave wake can also generate superthermal electrons that can preheat the core and/or the ablator. Electron beam stopping plays a critical role in the Fast Ignition (FI) ICF concept, in which a beam of relativistic electrons is used to heat the target core to ignition temperatures after the compression stage. The beam stopping power determines the effectiveness of the heating process. This dissertation covers new discoveries on the importance of plasma wave wakes in both BSRS and electron beam stopping. In the SRS studies, 1D particle-in-cell (PIC) simulations using OSIRIS are performed, which model a short-duration (˜500/?0 --1FWHM) counter-propagating scattered light seed pulse in the presence of a constant pump laser with an intensity far below the absolute instability threshold for plasma waves undergoing Landau damping. The seed undergoes linear convective Raman amplification and dominates over the amplification of fluctuations due to particle discreteness. The simulation results are in good agreement with results from a coupled-mode solver when special relativity and the effects of finite size PIC simulation particles are accounted for. Linear gain spectra including both effects are discussed. Extending the PIC simulations past when the seed exits the simulation domain reveals bursts of large-amplitude scattering in many cases, which do not occur in simulations without the seed pulse. These bursts can have amplitudes several times greater than the amplified seed pulse, and an examination of the orbits of particles trapped in the wake illustrates that the bursts are caused by a reduction of Landau damping due to particle trapping. This large-amplitude scattering is caused by the seed inducing a wake earlier in the simulation, thus modifying the distribution function. Performing simulations with longer duration seeds leads to parts of the seeds reaching amplitudes several times more than the steady-state linear theory results, similarly caused by a reduction of Landau damping. Simulations with continuous seeds demonstrate that the onset of inflation depends on the seed wavelength and incident intensity, and oscillations in the reflectivity are observed at a frequency equal to the difference between the seed frequency and the frequency at which the inflationary SRS grows. In the electron beam stopping studies, 3D PIC simulations are performed of relativistic electrons with a momentum of 10mec propagating in a cold FI core plasma. Some of the simulations use one simulation particle per real particle, and particle sizes much smaller than the interparitcle spacing. The wake made by a single electron is compared against that calculated using cold fluid theory assuming the phase velocity of the wake is near the speed of light. The results agree for the first wavelength of the wake. However, the shape of the wake changes for succeeding wavelengths and depends on the background plasma temperature, with the concavity pointing in the direction the electron is moving in cold plasmas and in the opposite direction as the plasma temperature increases. In the warm plasma the curvature is described by electrostatic Vlasov theory (for vparticle >> vth) and is due

Ellis, Ian Norman

435

Basic concepts in plasma accelerators.  

PubMed

In this article, we present the underlying physics and the present status of high gradient and high-energy plasma accelerators. With the development of compact short pulse high-brightness lasers and electron and positron beams, new areas of studies for laser/particle beam-matter interactions is opening up. A number of methods are being pursued vigorously to achieve ultra-high-acceleration gradients. These include the plasma beat wave accelerator (PBWA) mechanism which uses conventional long pulse ( approximately 100 ps) modest intensity lasers (I approximately 10(14)-10(16) W cm(-2)), the laser wakefield accelerator (LWFA) which uses the new breed of compact high-brightness lasers (<1 ps) and intensities >10(18) W cm(-2), self-modulated laser wakefield accelerator (SMLWFA) concept which combines elements of stimulated Raman forward scattering (SRFS) and electron acceleration by nonlinear plasma waves excited by relativistic electron and positron bunches the plasma wakefield accelerator. In the ultra-high intensity regime, laser/particle beam-plasma interactions are highly nonlinear and relativistic, leading to new phenomenon such as the plasma wakefield excitation for particle acceleration, relativistic self-focusing and guiding of laser beams, high-harmonic generation, acceleration of electrons, positrons, protons and photons. Fields greater than 1 GV cm(-1) have been generated with monoenergetic particle beams accelerated to about 100 MeV in millimetre distances recorded. Plasma wakefields driven by both electron and positron beams at the Stanford linear accelerator centre (SLAC) facility have accelerated the tail of the beams. PMID:16483948

Bingham, Robert

2006-03-15

436

Frequency dependence of the plasma density for helicon plasmas  

SciTech Connect

Variations of plasma density are investigated as a function of frequency of rf power in a helicon plasma source. Abrupt, almost step-like changes in the plasma density are observed during the frequency scans under various conditions of the input rf power, the argon gas pressure, and the magnetic field. It is found that the transition frequencies shift to the lower value region as the input rf power and/or the argon gas pressure is increased, and to the higher value region as the magnetic field is increased. The observed density transitions are compared with semianalytical calculations based on the power balance relation and it has been shown that the results are in good agreement. {copyright} {ital 1997 American Institute of Physics.}

Kwak, J.G.; Choi, H.D.; Bak, H.I. [Department of Nuclear Engineering, Seoul National University, Seoul, 151-742 (Korea)] [Department of Nuclear Engineering, Seoul National University, Seoul, 151-742 (Korea); Cho, S. [Department of Physics, Kyonggi University, Suwon, Kyonggi-Do, 442-760 (Korea)] [Department of Physics, Kyonggi University, Suwon, Kyonggi-Do, 442-760 (Korea); Bak, J.G.; Kim, S.K. [Nuclear Fusion Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Taejon, 305-600 (Korea)] [Nuclear Fusion Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Taejon, 305-600 (Korea)

1997-05-01

437

Production of a Low Energy, Low Temperature Plasma  

Microsoft Academic Search

Low temperature, high density plasmas are important to study space plasmas, dusty plasmas and processing plasmas, because in high temperature plasmas negative ions or radicals disappear. Ion beams generated by the sheath potential are effective and useful for the usual processing plasmas, however, are difficult to be controlled. The low energy plasma beams, whose ions have given velocity and are

Hiroko Kiyama; Satoru Kiyama

1997-01-01

438

Plasma propulsion for space applications  

NASA Astrophysics Data System (ADS)

The various mechanisms for plasma acceleration employed in electric propulsion of space vehicles will be described. Special attention will be given to the Hall thruster. Electric propulsion utilizes electric and magnetic fields to accelerate a propellant to a much higher velocity than chemical propulsion does, and, as a result, the required propellant mass is reduced. Because of limitations on electric power density, electric thrusters will be low thrust engines compared with chemical rockets. The large jet velocity and small thrust of electric thrusters make them most suitable for space applications such as station keeping of GEO communication satellites, low orbit drag compensation, orbit raising and interplanetary missions. The acceleration in the thruster is either thermal, electrostatic or electromagnetic. The arcjet is an electrothermal device in which the propellant is heated by an electric arc and accelerated while passing through a supersonic nozzle to a relatively low velocity. In the Pulsed Plasma Thruster a solid propellant is accelerated by a magnetic field pressure in a way that is similar in principle to pulsed acceleration of plasmas in other, very different devices, such as the railgun or the plasma opening switch. Magnetoplasmadynamic thrusters also employ magnetic field pressure for the acceleration but with a reasonable efficiency at high power only. In an ion thruster ions are extracted from a plasma through a double grid structure. Ion thrusters provide a high jet velocity but the thrust density is low due to space-charge limitations. The Hall thruster, which in recent years has enjoyed impressive progress, employs a quasi-neutral plasma, and therefore is not subject to a space-charge limit on the current. An applied radial magnetic field impedes the mobility of the electrons so that the applied potential drops across a large region inside the plasma. Methods for separately controlling the profiles of the electric and the magnetic fields will be described. The role of the sonic transition in plasma accelerators will be discussed. It will be shown that large potential drops can be localized to regions of an abrupt sonic transition in a Hall plasma. A configuration with segmented side electrodes can be used to further control the electric field profile and to increase the efficiency.

Fruchtman, Amnon

2000-04-01

439

Non-thermal atmospheric plasmas in dentistry  

NASA Astrophysics Data System (ADS)

Non-thermal atmospheric plasmas are very efficient in the deactivation of bacteria. A relatively new area is the use of these plasmas in biomedical and dental applications. In this work, application of a novel device in dentistry is investigated, the plasma needle. The plasma needle is used to generate a non-thermal atmospheric micro-plasma. A promising application of this micro-plasma is the treatment of dental cavities, to stop caries without causing pain and removing too much healthy tissue. Various bacterial model systems are used to test the bactericidal efficiency of the plasma needle: bacteria in droplets, thin films and (multi-species) biofilms. The effects of plasma needle treatment on bacterial viability, growth and composition are discussed. The results indicate that plasma can become a useful tool for dental treatment.

Sladek, Raymond; Stoffels, Eva

2006-10-01

440

Micro-column plasma emission liquid chromatograph  

DOEpatents

In a direct current plasma emission spectrometer for use in combination with a micro-column liquid chromatograph, an improved plasma source unit. The plasma source unit includes a quartz capillary tube having an inlet means, outlet off gas means and a pair of spaced electrodes defining a plasma region in the tube. The inlet means is connected to and adapted to receive eluant of the liquid chromatograph along with a stream of plasma-forming gas. There is an opening through the wall of the capillary tube penetrating into the plasma region. A soft glass capillary light pipe is disposed at the opening, is connected to the spectrometer, and is adapted to transmit light passing from the plasma region to the spectrometer. There is also a source of electromotive force connected to the electrodes sufficient to initiate and sustain a plasma in the plasma region of the tube.

Gay, Don D. (Aiken, SC)

1984-01-01

441

Summary of basic plasma physics and applications.  

NASA Astrophysics Data System (ADS)

Is basic plasma physics still alive, and if so, where is it being pursued? Some answers to these questions can be found in the statistics of the papers presented at this conference. The contributed papers were divided into the 13 subject: tokamaks and stellarators; alternate confinement systems; heating and current drive; plasma edge physics; inertial confinement fusion; space plasmas; astrophysical plasmas; general plasma theory; general plasma diagnostics; partially ionized plasmas; elementary processes; basic collisionless plasmas; plasma applications. Further insight can be gained from the geographical distribution of the origin of the papers at the conference. These numbers indicate not only the existence of basis research, but also the availability of adequate funding for the presentation of results.

Chen, F. F.

442

Phenomena on Plasma-Liquid Interface  

NASA Astrophysics Data System (ADS)

Recent researches on plasma-liquid interface are introduced. One is about plasma-water interaction at the interface of pulsed dielectric-barrier plasma in gas-liquid two-phase flow for water treatment. Acetic acid in water is decomposed as a persistent material. Numerical calculation indicates that plasma-water interaction which is O-radical-induced generation of liquid-phase-OH radical occurs. The other reports highly-concentrated adsorption of a surfactant at plasma-water interface, and an interfacial reaction decomposing the surfactant. Perfluorooctane sulfonic acid is an extremely persistent surfactant, but can be decomposed by plasma attached to the solution. The decomposing reaction occurs at the plasma-water interface. Estimation of the amount of PFOS adsorbing to the plasma-water interface shows much higher mole fraction of PFOS than that in bulk water. Thus, the plasma can effectively react with PFOS at the water surface and exhibits high energy efficiency.

Takeuchi, Nozomi

443

Portable nanosecond pulsed air plasma jet  

SciTech Connect

Low-temperature atmospheric pressure plasmas are of great importance in many emerging biomedical and materials processing applications. The redundancy of a vacuum system opens the gateway for highly portable plasma systems, for which air ideally becomes the plasma-forming gas and remote plasma processing is preferred to ensure electrical safety. Typically, the gas temperature observed in air plasma greatly exceeds that suitable for the processing of thermally liable materials; a large plasma-sample distance offers a potential solution but suffers from a diluted downstream plasma chemistry. This Letter reports a highly portable air plasma jet system which delivers enhanced downstream chemistry without compromising the low temperature nature of the discharge, thus forming the basis of a powerful tool for emerging mobile plasma applications.

Walsh, J. L. [Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, Merseyside L69 3GJ (United Kingdom); Kong, M. G. [Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom)

2011-08-22

444

Plasma vitrification of asbestos fibers  

SciTech Connect

Asbestos is a mineral in the form of long, thread-like fibers. Asbestos fibers have been among the best insulators of pipes, boilers, ducts, tanks, etc., in buildings, ships, and industrial furnaces. Over 150,000 metric tons of asbestos were consumed in the United States in 1984. The Environmental Protection Agency has declared asbestos fibers a known human carcinogen. And today, asbestos insulators are being replaced by manmade non-hazardous fibers. Millions of tons of replaced asbestos fiber insulators are in storage, awaiting the demonstration of effective alternative disposal technologies. Plasma vitrification has been demonstrated during May, June and July 1995 as a viable, cost-effective, safe technology for asbestos fiber disposal. A low-mass plasma arc heater is submerged under the waste asbestos insulating materials, and the intense heat of the plasma flame heats and melts the fibers. The by-product is dark, non-hazardous glass pellets. The vitrification process renders the asbestos waste safe for use as road construction aggregates or other fill materials. This paper will describe the results of start-up of a 1 ton-per-hour Plasma Mobile Asbestos Vitrification (MAV) Plant at a DOD Site in Port Clinton, Ohio. The Plasma MAV Plant is being demonstrated for the on-site disposal of 1.5 million pounds of Amosite asbestos fibers.

Camacho, S.L. [Plasma Technology Corp., Raleigh, NC (United States)

1995-12-31

445

Genetic determinants of plasma triglycerides  

PubMed Central

Plasma triglyceride (TG) concentration is reemerging as an important cardiovascular disease risk factor. More complete understanding of the genes and variants that modulate plasma TG should enable development of markers for risk prediction, diagnosis, prognosis, and response to therapies and might help specify new directions for therapeutic interventions. Recent genome-wide association studies (GWAS) have identified both known and novel loci associated with plasma TG concentration. However, genetic variation at these loci explains only ?10% of overall TG variation within the population. As the GWAS approach may be reaching its limit for discovering genetic determinants of TG, alternative genetic strategies, such as rare variant sequencing studies and evaluation of animal models, may provide complementary information to flesh out knowledge of clinically and biologically important pathways in TG metabolism. Herein, we review genes recently implicated in TG metabolism and describe how some of these genes likely modulate plasma TG concentration. We also discuss lessons regarding plasma TG metabolism learned from various genomic and genetic experimental approaches. Treatment of patients with moderate to severe hypertriglyceridemia with existing therapies is often challenging; thus, gene products and pathways found in recent genetic research studies provide hope for development of more effective clinical strategies. PMID:21041806

Johansen, Christopher T.; Kathiresan, Sekar; Hegele, Robert A.

2011-01-01

446

Fundamental studies of fusion plasmas  

SciTech Connect

Work on ICRF interaction with the edge plasma is reported. ICRF generated convective cells have been established as an important mechanism for influencing edge transport and interaction with the H-mode, and for controlling profiles in the tokamak scrape-off-layer. Power dissipation by rf sheaths has been shown to be significant for some misaligned ICRF and IIBW antenna systems. Near-field antenna sheath work has been extended to the far-field case, important for experiments with low single pass absorption. Impurity modeling and Faraday screen design support has been provided for the ICRF community. In the area of core-ICRF physics, the kinetic theory of heating by applied ICRF waves has been extended to retain important geometrical effects relevant to modeling minority heated tokamak plasmas, thereby improving on the physics base that is standard in presently employed codes. Both the quasilinear theory of ion heating, and the plasma response function important in wave codes have been addressed. In separate studies, it has been shown that highly anisotropic minority heated plasmas can give rise to unstable field fluctuations in some situations. A completely separate series of studies have contributed to the understanding of tokamak confinement physics. Additionally, a diffraction formalism has been produced which will be used to access the focusability of lower hybrid, ECH, and gyrotron scattering antennas in dynamic plasma configurations.

Aamodt, R.E.; Catto, P.J.; D'Ippolito, D.A.; Myra, J.R.; Russell, D.A.

1993-04-27

447

EDITORIAL: Focus on Plasma Medicine  

NASA Astrophysics Data System (ADS)

'Plasma Healthcare' is an emerging interdisciplinary research topic of rapidly growing importance, exploring considerable opportunities at the interface of plasma physics, chemistry and engineering with life sciences. Some of the scientific discoveries reported so far have already demonstrated clear benefits for healthcare in areas of medicine, food safety, environmental hygiene, and cosmetics. Examples include ongoing studies of prion inactivation, chronic wound treatment and plasma-mediated cancer therapy. Current research ranges from basic physical processes, plasma chemical design, to the interaction of plasmas with (i) eukaryotic (mammalian) cells; (ii) prokaryotic (bacteria) cells, viruses, spores and fungi; (iii) DNA, lipids, proteins and cell membranes; and (iv) living human, animal and plant tissues in the presence of biofluids. Of diverse interests in this new field is the need for hospital disinfection, in particular with respect to the alarming increase in bacterial resistance to antibiotics, the concomitant needs in private practices, nursing homes etc, the applications in personal hygiene—and the enticing possibility to 'design' plasmas as possible pharmaceutical products, employing ionic as well as molecular agents for medical treatment. The 'delivery' of the reactive plasma agents occurs at the gaseous level, which means that there is no need for a carrier medium and access to the treatment surface is optimal. This focus issue provides a close look at the current state of the art in Plasma Medicine with a number of forefront research articles as well as an introductory review. Focus on Plasma Medicine Contents Application of epifluorescence scanning for monitoring the efficacy of protein removal by RF gas-plasma decontamination Helen C Baxter, Patricia R Richardson, Gaynor A Campbell, Valeri I Kovalev, Robert Maier, James S Barton, Anita C Jones, Greg DeLarge, Mark Casey and Robert L Baxter Inactivation factors of spore-forming bacteria using low-pressure microwave plasmas in an N2 and O2 gas mixture M K Singh, A Ogino and M Nagatsu Degradation of adhesion molecules of G361 melanoma cells by a non-thermal atmospheric pressure microplasma H J Lee, C H Shon, Y S Kim, S Kim, G C Kim and M G Kong The acidification of lipid film surfaces by non-thermal DBD at atmospheric pressure in air A Helmke, D Hoffmeister, N Mertens, S Emmert, J Schuette and W Vioel Reduction and degradation of amyloid aggregates by a pulsed radio-frequency cold atmospheric plasma jet D L Bayliss, J L Walsh, G Shama, F Iza and M G Kong The effect of low-temperature plasma on bacteria as observed by repeated AFM imaging René Pompl, Ferdinand Jamitzky, Tetsuji Shimizu, Bernd Steffes, Wolfram Bunk, Hans-Ulrich Schmidt, Matthias Georgi, Katrin Ramrath, Wilhelm Stolz, Robert W Stark, Takuya Urayama, Shuitsu Fujii and Gregor Eugen Morfill Removal and sterilization of biofilms and planktonic bacteria by microwave-induced argon plasma at atmospheric pressure Mi Hee Lee, Bong Joo Park, Soo Chang Jin, Dohyun Kim, Inho Han, Jungsung Kim, Soon O Hyun, Kie-Hyung Chung and Jong-Chul Park Cell permeabilization using a non-thermal plasma M Leduc, D Guay, R L Leask and S Coulombe Physical and biological mechanisms of direct plasma interaction with living tissue Danil Dobrynin, Gregory Fridman, Gary Friedman and Alexander Fridman Nosocomial infections-a new approach towards preventive medicine using plasmas G E Morfill, T Shimizu, B Steffes and H-U Schmidt Generation and transport mechanisms of chemical species by a post-discharge flow for inactivation of bacteria Takehiko Sato, Shiroh Ochiai and Takuya Urayama Low pressure plasma discharges for the sterilization and decontamination of surfaces F Rossi, O Kylián, H Rauscher, M Hasiwa and D Gilliland Contribution of a portable air plasma torch to rapid blood coagulation as a method of preventing bleeding S P Kuo, O Tarasenko, J Chang, S Popovic, C Y Chen, H W Fan, A Scott, M Lahiani, P Alusta, J D Drake and M Nikolic A two-dimensional cold atmospheric plasma jet array for uniform treatment of large-area

Morfill, G. E.; Kong, M. G.; Zimmermann, J. L.

2009-11-01

448

Plasma Processing of Advanced Materials  

SciTech Connect

Plasma Processing of Advanced Materials The project had the overall objective of improving our understanding of the influences of process parameters on the properties of advanced superhard materials. The focus was on high rate deposition processes using thermal plasmas and atmospheric pressure glow discharges, and the emphasis on superhard materials was chosen because of the potential impact of such materials on industrial energy use and on the environment. In addition, the development of suitable diagnostic techniques was pursued. The project was divided into four tasks: (1) Deposition of superhard boron containing films using a supersonic plasma jet reactor (SPJR), and the characterization of the deposition process. (2) Deposition of superhard nanocomposite films in the silicon-nitrogen-carbon system using the triple torch plasma reactor (TTPR), and the characterization of the deposition process. (3) Deposition of films consisting of carbon nanotubes using an atmospheric pressure glow discharge reactor. (4) Adapting the Thomson scattering method for characterization of atmospheric pressure non-uniform plasmas with steep spatial gradients and temporal fluctuations. This report summarizes the results.

Heberlein, Joachim, V.R.; Pfender, Emil; Kortshagen, Uwe

2005-02-28

449

Relativistic Laser-Plasma Interactions  

SciTech Connect

Ever since the much acclaimed paper of Akhiezer and Polovin plasma theorists have been attempting to comprehend complex dynamics related to the propagation of high and ultra-high intensity electromagnetic (EM) radiation through a plasma. This topic was successfully revisited a number of years later by Kaw and Dawson whose analysis threw more light on the propagation of coupled longitudinal-transverse waves of arbitrary intensity. The high phase velocity case was soon solved exactly by Max and Perkins, (early review). The problem of relativistic laser-plasma interactions is of particular interest concerning the fast ignition concept, relevant to contemporary laser inertial confinement fusion research. Moreover, the understanding of relativistic laser pulse evolution in a plasma is basic to many new applications, including optical-field-ionized x-ray lasers, plasma-based electron accelerator schemes, as well as, interpretation of some astrophysical phenomena, and references, therein). From a text given in two tutorial lectures, in a limited space, we mainly focus on an important paradigm of stimulated Raman scattering.

Skoric, Milos M. [National Institute for Fusion Science, Graduate University of Advanced Studies, Toki-shi (Japan)

2009-11-10

450

Plasma Jet Modeling for PLX  

NASA Astrophysics Data System (ADS)

The implicit simulation code ePLAS has been applied to plasma jets generated with mini-rail guns for plasma production and compression aimed at use with PLX. The rails are typically planar, 2.5 cm apart and arranged to transport an initial 1 cm or wider vertical plasma fill some 10 cm into a void. The driving magnetic field is 3.2 T. The plasma singly ionized argon at 10^17 cm-3. We use ePLAS in both its traditional implicit/hybrid form [1] where it is restricted by an electron Courant time step, and in a new super-hybrid form that extracts the main electron moments from the E&B-field solutions. This provides numerical stability at ion Courant limits, for at least a 10 times larger time step, thus probing microsecond jet dynamics with computational economy. We examine possible field penetration at the cathode and anode gun electrodes. Cathode erosion and EMHD B-Field penetration are possible at lower jet densities [2]. We examine jet transport beyond the gun, modeling possible ionization with either analytic or tabular EOSs. We study the merger of jets with ions represented as either fluids or particles.[4pt] [1] R. J. Mason and C. Cranfill, IEEE Trans. Plasma Sci. PS-14, 45 (1986)[0pt] [2] R. Mason, et al., Phys. Fluids B, 5, 1115 (1993).

Mason, Caroline F.; Mason, Rodney J.; Faehl, R. J.; Kirkpatrick, R. C.

2011-11-01

451

Isochoric Plasma Sources for Laser-Plasma Interaction Studies  

NASA Astrophysics Data System (ADS)

The resonant backward Raman compression of intense laser light in plasma requires a high-density plasma that is easily accessed by light. Gas jet technology is at its limit: either in density, so new technology is necessary to process shorter wavelength light; or in geometrical size, so new technology is necessary to process substantial powers at large aperture. However, aerogel or dense aerosol targets may overcome the limitations of gas jets. We present scaling relations that define the operating parameter space for compression using silica aerogels. Using Ansys Fluent we simulate dense aerosol formation under aerodynamic focusing. These simulations include momentum coupling between the carrier gas and the particles' virtual flow field.

Hay, Michael J.; Valeo, Ernest J.; Fisch, Nathaniel J.

2011-11-01

452

Theoretical approach for plasma series resonance effect in geometrically symmetric dual radio frequency plasma  

SciTech Connect

Plasma series resonance (PSR) effect is well known in geometrically asymmetric capacitively couple radio frequency plasma. However, plasma series resonance effect in geometrically symmetric plasma has not been properly investigated. In this work, a theoretical approach is made to investigate the plasma series resonance effect and its influence on Ohmic and stochastic heating in geometrically symmetric discharge. Electrical asymmetry effect by means of dual frequency voltage waveform is applied to excite the plasma series resonance. The results show considerable variation in heating with phase difference between the voltage waveforms, which may be applicable in controlling the plasma parameters in such plasma.

Bora, B.; Bhuyan, H.; Favre, M.; Wyndham, E.; Chuaqui, H. [Pontificia Universidad Catolica de Chile, Departamento de Fisica, Casilla 306, Santiago 22 (Chile)

2012-02-27

453

Measurements of the Plasma Parameters and Low Frequency Oscillations in the Fisk Plasma Source  

NASA Technical Reports Server (NTRS)

A new plasma device, the Fisk Plasma Source (FPS), has been developed at Fisk University. This plasma device is used to study the physics of low temperature plasmas and plasma-material interactions. The FPS device is a stainless steel vacuum 6-way cross vacuum vessel with at 10-inch inner diameter. Low temperature argon plasmas are generated using DC glow discharge and thermionic filament techniques. Spatial profiles of the plasma density, plasma potential, and electron temperature are measured using Langmuir probes. We present initial experimental measurements of density and temperature profiles in the FPS device. Experimental and theoretical studies of low frequency oscillations observed in the FPS device are also presented.

Thomas, Edward, Jr.; Wallace, Kent; Lampkin, Gregory; Watson, Michael

1998-01-01

454

Wakefield generation in magnetized plasmas.  

PubMed

We consider wakefield generation in plasmas by electromagnetic pulses propagating perpendicular to a strong magnetic field, in the regime where the electron cyclotron frequency is equal to or larger than the plasma frequency. Particle-in-cell simulations reveal that for moderate magnetic field strengths previous results are reproduced, and the wakefield wave number spectrum has a clear peak at the inverse skin depth. However, when the cyclotron frequency is significantly larger than the plasma frequency, the wakefield spectrum becomes broadband, and simultaneously the loss rate of the driving pulse is much enhanced. A set of equations for the scalar and vector potentials reproducing these results are derived, using only the assumption of a weakly nonlinear interaction. PMID:22060515

Holkundkar, Amol; Brodin, Gert; Marklund, Mattias

2011-09-01

455

Confinement of high temperature plasmas  

US Patent & Trademark Office Database

A high temperature plasma is magnetically confined without leaks or cusps in a smooth toroidal configuration by tangential magnetic field lines on its surface which have a zero rotation number, and include a selected finite even non-zero number of closed toroidal magnetic field lines, which are limit cycles in the sense that all other surface field lines are asympototic to neighboring pairs of these closed field lines, and the poloidal cross-section of the plasma is non-convex. The resulting unique structure makes the confined plasma relatively insensitive to approximations, tolerances, and variations in the parameters of design, construction and operation. Furthermore, use of the sense of averaging appropriate to evaluation of interchange instabilities shows that the resulting magnetic bottle is an optimal toroidal magnetic well.

1980-12-02

456

Plasma production via field ionization  

NASA Astrophysics Data System (ADS)

Plasma production via field ionization occurs when an incoming particle beam is sufficiently dense that the electric field associated with the beam ionizes a neutral vapor or gas. Experiments conducted at the Stanford Linear Accelerator Center explore the threshold conditions necessary to induce field ionization by an electron beam in a neutral lithium vapor. By independently varying the transverse beam size, number of electrons per bunch, or bunch length, the radial component of the electric field is controlled to be above or below the threshold for field ionization. Additional experiments ionized neutral xenon and neutral nitric oxide by varying the incoming beam’s bunch length. A self-ionized plasma is an essential step for the viability of plasma-based accelerators for future high-energy experiments.

O'Connell, C. L.; Barnes, C. D.; Decker, F.-J.; Hogan, M. J.; Iverson, R.; Krejcik, P.; Siemann, R.; Walz, D. R.; Clayton, C. E.; Huang, C.; Johnson, D. K.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W.; Zhou, M.; Deng, S.; Katsouleas, T.; Muggli, P.; Oz, E.

2006-10-01

457

Interdisciplinary research with complex plasmas  

SciTech Connect

In this topical review we combine results of research from the field of complex plasmas and colloidal dispersions. This research has opened the way to study strong coupling phenomena in real space and time at the most fundamental kinetic level. The physics of complex plasmas is dominated by the dynamics of slow moving and individually visible microparticles. In contrast to colloidal suspensions, where the fluid background medium results in huge overdamping, the neutral gas background medium in complex plasmas introduces only very little damping so that processes at all relevant time scales can be studied. This is of particular importance for some of the most outstanding questions in the self-organization of matter and critical phenomena.

Morfill, G. E.; Ivlev, A. V.; Brandt, P. [Max-Planck-Institut fuer extraterrestrische Physik, 85741 Garching (Germany); Loewen, H. [Heinrich-Heine-Universitaet Duesseldorf, 40225 Duesseldorf (Germany)

2010-06-16

458

Double layer formation. [in plasma  

NASA Technical Reports Server (NTRS)

An investigation is conducted of the plasma processes which occur during the formation of a double layer in response to an applied initial electric field, when triggered by a current in the plasma. The important feature of the formation process was the creation of an ion-rich plasma-density cavity. The positive space charge of the cavity was shielded by induction of a negative space charge on the low potential side of the cavity, giving rise to the formation of a fully developed double layer. The shielding was complete only when the electron current from the low potential side exceeded the electron thermal current. It was found that during the formation of double layers counterstreaming electrons are generated. Moreover, transient double layers with reverse polarity also occur during this phase. Thus, the recurring formation of double layers can give rise to flickering double layers.

Singh, N.

1982-01-01

459

Particle transport in plasma reactors  

SciTech Connect

SEMATECH and the Department of Energy have established a Contamination Free Manufacturing Research Center (CFMRC) located at Sandia National Laboratories. One of the programs underway at the CFMRC is directed towards defect reduction in semiconductor process reactors by the application of computational modeling. The goal is to use fluid, thermal, plasma, and particle transport models to identify process conditions and tool designs that reduce the deposition rate of particles on wafers. The program is directed toward defect reduction in specific manufacturing tools, although some model development is undertaken when needed. The need to produce quantifiable improvements in tool defect performance requires the close cooperation among Sandia, universities, SEMATECH, SEMATECH member companies, and equipment manufacturers. Currently, both plasma (e.g., etch, PECVD) and nonplasma tools (e.g., LPCVD, rinse tanks) are being worked on under this program. In this paper the authors summarize their recent efforts to reduce particle deposition on wafers during plasma-based semiconductor manufacturing.

Rader, D.J.; Geller, A.S.; Choi, Seung J. [Sandia National Labs., Albuquerque, NM (United States); Kushner, M.J. [Illinois Univ., Urbana, IL (United States)

1995-01-01

460

The dayside midlatitude plasma trough  

NASA Technical Reports Server (NTRS)

The electrostatic probe experiment aboard the ISIS-1 satellite detects a quasi-stable dayside plasma trough in the protonosphere with a characteristic time of at least 2 weeks. This behavior contrasts with measurements at 1000 km from Explorer-22, which indicate a trough of a characteristic time less than a satellite orbit period. Associated with the protonospheric trough is an electron temperature maximum approximately 6000 K that is sharp at midnight and broad at noon. In spring and summer, a second noontime temperature maximum often appears poleward of 70 invariant latitude, accompanied by an enhancement in the ionization. The ISIS-1 data indicates that local processes such as dayside F-region photoionization and ionization by energetic cusp particles produce enhancements in plasma density and electron temperature. These enhancements modify the plasmaspheric boundary to varying degrees along a magnetic field tube, thus leading to a plasmas pheric boundary with distinctive features at various positions along a field tube.

Miller, N. J.

1973-01-01

461

Object Oriented Plasma Process Modelling  

NASA Astrophysics Data System (ADS)

Models for multi-dimensional plasma source simulations are becoming more and more complex. Issues as important as the physics in the model or simulation are maintainability, portability, and adaptability. The ideal is that a simulation be able to access physics modules, geometry information or chemistry data, for example, through a seamless connection. Object oriented models address these needs. Moreover, for a much repeated process in a simulation, such as sampling in a Monte Carlo simulation, it is important to treat sampling as an object so that 1) it may be easily accessed and 2) engineered without threat to the integrity of the simulation. Object oriented languages like JAVA are well suited for these tasks. Using JAVA we illustrate the methodology of object oriented plasma simulation for Legendre Polynomial Weighted Sampling (LPWS) in a Monte Carlo simulation of an inductively coupled plasma (ICP) source as an example.

Horie, I.; Kitamori, K.; Ogawa, U.; Ventzek, P. L. G.

1997-10-01

462

Ultrarelativistic electromagnetic pulses in plasmas  

NASA Technical Reports Server (NTRS)

The physical processes of a linearly polarized electromagnetic pulse of highly relativistic amplitude in an underdense plasma accelerating particles to very high energies are studied through computer simulation. An electron-positron plasma is considered first. The maximum momenta achieved scale as the square of the wave amplitude. This acceleration stops when the bulk of the wave energy is converted to particle energy. The pulse leaves behind as a wake a vacuum region whose length scales as the amplitude of the wave. The results can be explained in terms of a snow plow or piston-like action of the radiation on the plasma. When a mass ratio other than unity is chosen and electrostatic effects begin to play a role, first the ion energy increases faster than the electron energy and then the electron energy catches up later, eventually reaching the same value.

Ashour-Abdalla, M.; Leboeuf, J. N.; Tajima, T.; Dawson, J. M.; Kennel, C. F.

1981-01-01

463

Plasma Panel Based Radiation Detectors  

SciTech Connect

The plasma panel sensor (PPS) is a gaseous micropattern radiation detector under current development. It has many operational and fabrication principles common to plasma display panels (PDPs). It comprises a dense matrix of small, gas plasma discharge cells within a hermetically sealed panel. As in PDPs, it uses non-reactive, intrinsically radiation-hard materials such as glass substrates, refractory metal electrodes, and mostly inert gas mixtures. We are developing these devices primarily as thin, low-mass detectors with gas gaps from a few hundred microns to a few millimeters. The PPS is a high gain, inherently digital device with the potential for fast response times, fine position resolution (< 50 m RMS) and low cost. In this paper we report here on prototype PPS experimental results in detecting betas, protons and cosmic muons, and we extrapolate on the PPS potential for applications including detection of alphas, heavy-ions at low to medium energy, thermal neutrons and X-rays.

Friedman, Dr. Peter S. [Integrated Sensors, LLC; Varner Jr, Robert L [ORNL; Ball, Robert [University of Michigan; Beene, James R [ORNL; Ben Moshe, M. [Tel Aviv University; Benhammou, Yan [Tel Aviv University; Chapman, J. Wehrley [University of Michigan; Etzion, E [Tel Aviv University; Ferretti, Claudio [University of Michigan; Bentefour, E [Ion Beam Applications; Levin, Daniel S. [University of Michigan; Moshe, M. [Tel Aviv University; Silver, Yiftah [Tel Aviv University; Weaverdyck, Curtis [University of Michigan; Zhou, Bing [University of Michigan

2013-01-01

464

Plasma-catalyzed fuel reformer  

DOEpatents

A reformer is disclosed that includes a plasma zone to receive a pre-heated mixture of reactants and ionize the reactants by applying an electrical potential thereto. A first thermally conductive surface surrounds the plasma zone and is configured to transfer heat from an external heat source into the plasma zone. The reformer further includes a reaction zone to chemically transform the ionized reactants into synthesis gas comprising hydrogen and carbon monoxide. A second thermally conductive surface surrounds the reaction zone and is configured to transfer heat from the external heat source into the reaction zone. The first thermally conductive surface and second thermally conductive surface are both directly exposed to the external heat source. A corresponding method and system are also disclosed and claimed herein.

Hartvigsen, Joseph J.; Elangovan, S.; Czernichowski, Piotr; Hollist, Michele

2013-06-11

465

Constricted glow discharge plasma source  

DOEpatents

A constricted glow discharge chamber and method are disclosed. The polarity and geometry of the constricted glow discharge plasma source is set so that the contamination and energy of the ions discharged from the source are minimized. The several sources can be mounted in parallel and in series to provide a sustained ultra low source of ions in a plasma with contamination below practical detection limits. The source is suitable for applying films of nitrides such as gallium nitride and oxides such as tungsten oxide and for enriching other substances in material surfaces such as oxygen and water vapor, which are difficult process as plasma in any known devices and methods. The source can also be used to assist the deposition of films such as metal films by providing low-energy ions such as argon ions.

Anders, Andre (Albany, CA); Anders, Simone (Albany, CA); Dickinson, Michael (San Leandro, CA); Rubin, Michael (Berkeley, CA); Newman, Nathan (Winnetka, IL)

2000-01-01

466

Nonlinear dynamics and plasma transport  

SciTech Connect

This progress report details work done on a program in nonlinear dynamical aspects of plasma turbulence and transport funded by DOE since 1989. This program has been in cooperation with laboratories in theUSSR [now Russia and the Confederation of Independent States (CIS)]. The purpose of this program has been: To promote the utilization of recent pathbreaking developments in nonlinear science in plasma turbulence and transport. To promote cooperative scientific investigations between the US and CIS in the related areas of nonlinear science and plasma turbulence and transport. In the work reported in our progress report, we have studied simple models which are motivated by observation on actual fusion devices. The models focus on the important physical processes without incorporating the complexity of the geometry of real devices. This allows for a deeper analysis and understanding of the system both analytically and numerically.

Antonsen, T.M. Jr.; Drake, J.F.; Finn, J.M.; Guzdar, P.N.; Hassam, A.B.; Sageev, R.Z.

1993-01-01

467

Plasma Channels and Accelerator Applications -- A Tutorial  

SciTech Connect

A plasma channel is a narrow preionized column of plasma that can be used for a number of accelerator applications. Plasma channels play a crucial role in the laser wakefield accelerator (LWFA), where they may provide the acceleration medium as well as guiding of the intense laser pulse and accelerated electron bunch. This paper will review methods for producing plasma channels, optical guiding in channels, and the application of channels to the LWFA. The potential advantages of using long plasma channels in the plasma wakefield accelerator (PWFA) will also be discussed.

Hubbard, Richard F. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375-5346 (United States)

2006-11-27

468

Plasma vortices in the ionosphere and atmosphere  

NASA Astrophysics Data System (ADS)

Vortices observed in ionized clouds of thunderstorm fronts have the nature of plasma vortices. In this work, the need to account for the electrostatic instability of plasma in the origination, intensification, and decay of plasma vortices in the atmosphere is shown. Moisture condensation results in mass-energy transfer under the inhomogeneous spatial distribution of aerosols. If a phase volume of natural oscillations is transformed in the frequency-wave vector space in inhomogeneous plasma, the damping of plasma oscillations promotes an increase in the pressure gradients normal to the geomagnetic field. Excitation of the gradient instabilities is probable in atmospheric plasma formations.

Izhovkina, N. I.

2014-11-01

469

Ferroelectric plasma thruster for microspacecraft propulsion  

SciTech Connect

This paper presents a technology in microthruster design: the ferroelectric plasma thruster (FEPT). The FEPT utilizes an applied rf electric field to create plasma on the surface of a ferroelectric dielectric. Acceleration of ions from this plasma provides thrust. Advantages of the FEPT include emission of both electrons and ions leading to self-neutralization, creation of plasma, and acceleration of ions with a single power supply, and application of thrust in a short amount of time. We present the concept of the thruster, operational physics, as well as experimental results demonstrating plasma creation and ion acceleration. These results along with plasma spectroscopy allow us to calculate thruster parameters.

Kemp, Mark A.; Kovaleski, Scott D. [Department of Electrical and Computer Engineering, University of Missouri-Columbia, Columbia, Missouri 65211 (United States)

2006-12-01

470

Comprehensive computational model for thermal plasma processing  

SciTech Connect

A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. The overall computational model is embodied in a new computer code called LAVA. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Plasma-particle interactions including turbulent dispersion have been modeled in a fully self- consistent manner. 17 refs.

Chang, C.H.

1992-01-01

471

Comprehensive computational model for thermal plasma processing  

SciTech Connect

A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. The overall computational model is embodied in a new computer code called LAVA. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Plasma-particle interactions including turbulent dispersion have been modeled in a fully self- consistent manner. 17 refs.

Chang, C.H.

1992-08-01