Development of a trielectrode plasma curtain at atmospheric pressure
H. Zastawny, R. Sosa, D. Grondona, A. Marquez, G. Artana et al.
The development of a nonequilibrium, low-power, trielectrode plasma curtain at atmospheric pressure is presented. The discharge is based on the combination of an ac dielectric barrier discharge with a dc corona discharge in a three electrode system, and can be sustained for large time periods and ov ... [Appl. Phys. Lett. 93, 031501 (2008)] published Wed Jul 23, 2008.
Unphysical kinetic effects in particle-in-cell modeling of laser wakefield accelerators
Estelle Cormier-Michel, B. A. Shadwick, C. G. R. Geddes, E. Esarey, C. B. Schroeder et al.
Unphysical heating and macroparticle trapping that arise in the numerical modeling of laser wakefield accelerators using particle-in-cell codes are investigated. A dark current free laser wakefield accelerator stage, in which no trapping of background plasma electrons into the plasma wave should occ ... [Phys. Rev. E 78, 016404 (2008)] published Wed Jul 23, 2008.
Numerical simulation of the Zeeman effect in neutral xenon from NIR diode-laser spectroscopy
Bailo B. Ngom, Timothy B. Smith, Wensheng Huang, and Alec D. Gallimore
We present a numerical method for simulating neutral xenon absorption spectra from diode-laser spectroscopy of the Zeeman-split 6S[1/2]-->6P[1/2] line at 834.682 nm-air in a galvatron's plasma. To simulate the spectrum, we apply a Voigt profile to a spectrum of sigma-transition lines of even- and od ... [J. Appl. Phys. 104, 023303 (2008)] published Wed Jul 23, 2008.
Simulation of high-power electromagnetic wave heating in the ITER burning plasma
E. F. Jaeger, L. A. Berry, E. F. D'Azevedo, R. F. Barrett, S. D. Ahern et al.
The next step toward fusion as a practical energy source is the design and construction of ITER [R. Aymar et al., Nucl. Fusion 41, 1301 (2001)], a device capable of producing and controlling the high-performance plasma required for self-sustaining fusion reactions, i.e., burning plasma. ITER relies ... [Phys. Plasmas 15, 072513 (2008)] published Tue Jul 22, 2008.
Controlled electron injection into the wake wave using plasma density inhomogeneity
A. V. Brantov, T. Zh. Esirkepov, M. Kando, H. Kotaki, V. Yu. Bychenkov et al.
The electron injection, for the laser wake field accelerator, controlled through the plasma density inhomogeneity is studied on a basis of analytical estimates and two- and three-dimensional particle-in-cell simulations. The injection scheme requires a concordance of the density scale length and las ... [Phys. Plasmas 15, 073111 (2008)] published Tue Jul 22, 2008.
The role of coherent vorticity in turbulent transport in resistive drift-wave turbulence
W. J. T. Bos, S. Futatani, S. Benkadda, M. Farge, and K. Schneider
The coherent vortex extraction method, a wavelet technique for extracting coherent vortices out of turbulent flows, is applied to simulations of resistive drift-wave turbulence in magnetized plasma (HasegawaWakatani system). The aim is to retain only the essential degrees of freedom, responsible for ... [Phys. Plasmas 15, 072305 (2008)] published Tue Jul 22, 2008.
Heat diffusion across magnetic islands and ergodized plasma regions in realistic tokamak geometry
M. Holzl, S. Gunter, and ASDEX Upgrade Team
Heat diffusion in magnetized plasmas is investigated numerically for tokamak geometry and realistic plasma parameters. Heat transport across single and overlapping magnetic islands is studied. As an application, the influence of an (n+1,m+1) helical perturbation onto the temperature perturbation cau ... [Phys. Plasmas 15, 072514 (2008)] published Tue Jul 22, 2008.
Observations of neutral depletion and plasma acceleration in a flowing high-power argon helicon plasma
C. Mark Denning, Matt Wiebold, and John E. Scharer
Neutral depletion effects are observed in a steady-state flowing argon helicon plasma with a magnetic nozzle for high rf input powers (up to 3 kW). Noninvasive diagnostics including 105 GHz microwave interferometry and optical spectroscopy with collisional-radiative modeling are used to measure th ... [Phys. Plasmas 15, 072115 (2008)] published Tue Jul 22, 2008.
Double probe circuit used in pulsed plasma diagnostics
B. A. Hoegger and A. Bulliard
The construction of a new double probe circuit using wide band optically isolated electronic elements is described. The circuit is adaptable to measuring plasma characteristics generted by pulsed discharges. The entire system is powered by a high performance dc/dc converter. The probe and ramp gener ... [Rev. Sci. Instrum. 51, 735 (2008)] published Tue Jul 22, 2008.
Low energy H atom analyzer using a cesium heat pipe
D. Brisson, F. W. Baity, B. H. Quon, J. A. Ray, and C. F. Barnett
The efficiency of detecting H and D atoms (E<1 keV) escaping a plasma has been increased by use of a cesium vapor cell to form negative ions by electron attachment collisions. A 30 cm long heat pipe confines the cesium to a localized region. The resulting negative ions are energy analyzed with a sin ... [Rev. Sci. Instrum. 51, 511 (2008)] published Tue Jul 22, 2008.
Quasiquadrature interferometer for plasma density radial profile measurements: Achieving ten channel operation
D. D. Lowenthal
A quadrature interferometer designed to measure radial electron density profiles in a long (3 m) small bore (2.8 cm) plasma tube, and described previously in this journal, has been further developed to have ten simultaneously operating channels. Achieving multichannel operation was essential to the ... [Rev. Sci. Instrum. 51, 440 (2008)] published Tue Jul 22, 2008.
Fluid insulator used in the investigation of gas phase ions with an electrometer
A. Auerbach
We describe a simple design modification which will solve the spurious surface charging effects associated with the use of sweep plates to investigate gaseous ions. The procedure involves using a fluid insulator to electrically isolate the electrometer electrode. ... [Rev. Sci. Instrum. 51, 254 (2008)] published Tue Jul 22, 2008.
Elmo Bumpy Torus heavy ion probe
F. M. Bieniosek, P. L. Colestock, K. A. Connor, R. L. Hickok, S. P. Kuo et al.
A diagnostic system based on the heavy ion beam probe technique has been developed for the Elmo Bumpy Torus. A variety of singly charged alkali metal ions have been used in the probing beam; detection of multiply charged reaction products allows a continuous spatially resolved monitor of the plasma ... [Rev. Sci. Instrum. 51, 206 (2008)] published Tue Jul 22, 2008.
On the possibility to measure volumes of small gas bubbles and the bubble producing gas flow rates acoustically
G. G. Oosterwegel and H. J. de Groot
Using the pulsation properties of gas bubbles it is possible to measure acoustically volumes c.q. equivalent diameters of gas bubbles in the range of 1.82.1 mm, produced at low frequencies at capillary tubes in a silent environment. Hence it is possible to measure very low gas flow rates (from 4 up ... [Rev. Sci. Instrum. 51, 201 (2008)] published Tue Jul 22, 2008.
A focussing hog-horn antenna for microwave diagnostics in plasma machines
M. Moresco, A. Vendramin, and E. Zilli
We describe the design of a type of millimeter wave antenna which is particularly suitable in plasma diagnostics applications. It is an all metal focussing hog-horn antenna. Its main advantages are high spatial resolution, capability of working at short distance, little space taken, wide band, rugge ... [Rev. Sci. Instrum. 51, 1071 (2008)] published Tue Jul 22, 2008.
Nanosecond light pulser with Hg vapor: Determination of quenching rate constants for Hg([sup 3]P[sub 1]) with H[sub 2], C[sub 2]H[sub 4], CO, and NH[sub 3]
T. Hikida, M. Santoku, and Y. Mori
A pulsed discharge lamp containing Hg vapor suitable for kinetic spectroscopy in the nanosecond time range is described. The spectral output is practically the same as that from a conventional low pressure mercury resoance lamp. The light intensity of the 253.7 nm resonance line is about 10 photon/p ... [Rev. Sci. Instrum. 51, 1063 (2008)] published Tue Jul 22, 2008.
New design for a microwave discharge lamp
Alain Glangetas
A simple discharge lamp with a microwave cavity fitting inside provides an intense source of VUV resonance radiation for photochemical work inside a vacuum chamber. Good coupling and minimum reabsorption result in better efficiency (>~1%) and more intense output power (up to 2.5 x 10 quanta s) than ... [Rev. Sci. Instrum. 51, 390 (2008)] published Tue Jul 22, 2008.
Measurement of the plasma potential with ion acoustic waves
L. Schott
Plasma potentials are determined from the bias of a Langmuir probe at which the ac probe current due to an externally excited ion wave vanishes. ... [Rev. Sci. Instrum. 51, 383 (2008)] published Tue Jul 22, 2008.
Stabilized flow in capillary-type closed viscometer
Hiroshi Kobayashi
Small periodic variations in a main gas flow through a capillary are reduced from 1% to 0.1% in peak-to-peak width by a feedback circuit between a pressure gauge and a motor of a pump. The variations in flow result from nonlinear transmission of a worm mechanism in a capillary-type closed viscometer ... [Rev. Sci. Instrum. 51, 357 (2008)] published Tue Jul 22, 2008.
Calorimetric system for recording plasma blowoff and scattered light distributions from laser plasmas
D. M. Villeneuve and M. C. Richardson
A complete system is described for the measurement of the distribution of energy emanating from laser-produced plasmas in the form of (1) plasma blowoff (ions, electrons, neutral particles, and x rays), and (2) scattered laser light. The detectors consist of small modules containing two differential ... [Rev. Sci. Instrum. 51, 306 (2008)] published Tue Jul 22, 2008.
Small barium rail gun for plasma injection
Y. Kiwamoto
A small rail gun with a barium electrode can be operated at higher than one shot per second to produce more than 2 x 10 barium ions with energy 1020 eV. The operation of the gun takes advantage of the external magnetic field for cross-field plasma injection into a trap. Up to 7 kG of the magnetic fi ... [Rev. Sci. Instrum. 51, 285 (2008)] published Tue Jul 22, 2008.
Cross-Field Transport by Instabilities and Blobs in a Magnetized Toroidal Plasma
M. Podesta, A. Fasoli, B. Labit, I. Furno, P. Ricci et al.
The mechanisms for anomalous transport across the magnetic field are investigated in a toroidal magnetized plasma. The role of plasma instabilities and macroscopic density structures (blobs) is discussed. Examples from a scenario with open magnetic field lines are shown. A transition from a main pla ... [Phys. Rev. Lett. 101, 045001 (2008)] published Tue Jul 22, 2008.
A modification of the laser detonation-type hyperthermal oxygen atom beam source for a long-term operation
Hiroshi Kinoshita, Shunsuke Yamamoto, Hideaki Yatani, and Nobuo Ohmae
It has been an impedimental problem, for the laser detonation-type atom beam generator, that a poppet in the pulsed supersonic valve is rapidly eroded by the irradiation of powerful laser light and high temperature plasma. In order to operate the atom beam source for a long duration, a modification ... [Rev. Sci. Instrum. 79, 073109 (2008)] published Tue Jul 22, 2008.
Neutron production from interactions of high-intensity ultrashort pulse laser with a planar deuterated polyethylene target
G. M. Petrov and J. Davis
The deuteron acceleration from a planar uniform deuterated polyethylene (CD) target was studied with a two-dimensional electromagnetic particle-in-cell method in the ultrarelativistic regime for peak laser intensities between 10 and 10 W/m. Under identical conditions the deuteron energy and angular ... [Phys. Plasmas 15, 073109 (2008)] published Mon Jul 21, 2008.
Surface charge in dielectric barrier discharge plasma actuators
D. F. Opaits, M. N. Shneider, Richard B. Miles, A. V. Likhanskii, and S. O. Macheret
Direct measurements of the dielectric surface potential and its dynamics in asymmetric dielectric barrier discharge (DBD) plasma actuators show that the charge builds up at the dielectric surface and extends far downstream of the plasma. The surface charge persists for a long time (tens of minutes) ... [Phys. Plasmas 15, 073505 (2008)] published Mon Jul 21, 2008.
Effect of dust charge fluctuation on the propagation of dust-ion acoustic waves in inhomogeneous mesospheric dusty plasma
A. E. Mowafy, E. K. El-Shewy, W. M. Moslem, and M. A. Zahran
Investigation of positive and negative dust charge fluctuations on the propagation of dust-ion acoustic waves (DIAWs) in a weakly inhomogeneous, collisionless, unmagnetized dusty plasmas consisting of cold positive ions, stationary positively and negatively charged dust particles and isothermal elec ... [Phys. Plasmas 15, 073708 (2008)] published Mon Jul 21, 2008.
Quasielectrostatic whistler wave radiation from the hot electron emission of a laser-produced plasma
Stephen Vincena, Walter Gekelman, M. A. Van Zeeland, James Maggs, and Andrew Collette
Measurements are presented of radiated wave electric fields which result from the creation of a dense, laser-produced plasma within a large, uniform background magnetoplasma. The radiated field patterns are consistent for waves propagating along the quasielectrostatic branch of the whistler wave dis ... [Phys. Plasmas 15, 072114 (2008)] published Mon Jul 21, 2008.
Critical Delta[sup [prime]] for stability of viscoresistive tearing modes
D. Grasso, R. J. Hastie, F. Porcelli, and C. Tebaldi
An analytic expression for the stability threshold of linear tearing modes is derived. The magnetized plasma is described in terms of a standard viscoresistive magnetohydrodynamic model. The analytic derivation requires an extension of the standard layer equation that represents an approximation of ... [Phys. Plasmas 15, 072113 (2008)] published Mon Jul 21, 2008.
Simultaneous resonant enhanced multiphoton ionization and electron avalanche ionization in gas mixtures
Mikhail N. Shneider, Zhili Zhang, and Richard B. Miles
Resonant enhanced multiphoton ionization (REMPI) and electron avalanche ionization (EAI) are measured simultaneously in Ar:Xe mixtures at different partial pressures of mixture components. A simple theory for combined REMPI+EAI in gas mixture is developed. It is shown that the REMPI electrons seed t ... [J. Appl. Phys. 104, 023302 (2008)] published Mon Jul 21, 2008.
Angular Dependence of the Etch Rates of TaN in CF[sub 4]/Ar and CHF[sub 3]/Ar Plasmas
Il-Yong Jang, Jin-Kwan Lee, Seung-Hang Lee, Sung-Min Huh, Hyuk Joo Kwon et al.
The etching characteristics of tantalum nitride (TaN), a mask absorber in extreme UV lithography, was investigated by observing the angular dependence of its normalized etch yield in CF/Ar and CHF/Ar inductively coupled plasmas (ICPs). The direction of plasma ions incident on the substrate surface w ... [J. Electrochem. Soc. 155, D614 (2008)] published Mon Jul 21, 2008.
Simultaneous closure of multiple high voltage parallel spark channels without switch: A parametric study
Pallavi Raote, Gautam Patil, J. Padma Nilaya, and Dhruba J. Biswas
Results of a detailed parametric study of a self-switched mutually inductively coupled high voltage parallel spark preionizer are presented. The maximal behavior exhibited by the breakdown voltage of the parallel gaps with respect to the number of mutually coupled turns has been explained. It has be ... [Appl. Phys. Lett. 93, 031103 (2008)] published Mon Jul 21, 2008.
Excitation of the plasma and lower oblique resonances in a Maxwellian magnetoplasma of weak density
J. Thiel and P. M. E. Decreau
In a Maxwellian magnetoplasma, where the plasma frequency is lower than the electron gyrofrequency, the plasma resonance may be excited at short distances and the lower oblique resonance at large distances from the source. ... [Phys. Fluids 23, 2334 (2008)] published Mon Jul 21, 2008.
Transport fluxes and currents in a multispecies tokamak plasma with external sources
W. M. Stacey, Jr.
Momentum balance, including external sources and drags, is used to uniquely determine the lowest order fluxes and the radial potential gradient in a multi-species tokamak plasma, from which transport fluxes and currents can be constructed. ... [Phys. Fluids 23, 2332 (2008)] published Mon Jul 21, 2008.
Relativistic dispersion relation for electron Bernstein waves
E. Lazzaro and A. Orefice
The relativistic electrostatic dispersion relation for a magnetized plasma is obtained and analyzed in the case of electron cyclotron waves traveling quasi-perpendicularly to the magnetic field. ... [Phys. Fluids 23, 2330 (2008)] published Mon Jul 21, 2008.
Necessary magnetohydrodynamic stability criterion for rotating plasmas
G. O. Spies and T. A. K. Hellsten
A stability criterion is derived for axially symmetric equilibria with a purely toroidal rigid mass rotation, a purely poloidal magnetic field, and constant entropy along the field lines. If this criterion is violated, unstable eigenvalues accumulate at the harmonics of the rotation frequency. ... [Phys. Fluids 23, 2328 (2008)] published Mon Jul 21, 2008.
Thermal and radiation losses in a linear device
Philip Rosenau and David Degani
An analysis is presented of the electron temperature in a linear device which includes the effect of thermal conduction, heat flux limit, radiation, and end plugs. It is found that the thermal conduction and the heat flux limit are dominant in the initial phase of cooling, while the later phase is a ... [Phys. Fluids 23, 2318 (2008)] published Mon Jul 21, 2008.
Resonant parametric excitations driven by lower-hybrid fields
E. Villalon
Three-wave parametric excitation in inhomogeneous plasmas is examined in a two-dimensional geometry relevant to supplementary rf heating of tokamaks. The stabilization of resonant parametric excitation due to a linear mismatch in wavenumbers and to the Landau-damping rates of the decay waves is anal ... [Phys. Fluids 23, 2308 (2008)] published Mon Jul 21, 2008.
Heating of a toroidal plasma by a nonuniform radio frequency field
Y. Amagishi, A. Hirose, and H. M. Skarsgard
Nonuniform electric fields created by an oscillating (1.8 MHz) dipole magnetic field are applied to a preformed, argon plasma in a torus with major radius R=19 cm, minor radius a=2.5 cm, and a toroidal magnetic field B=0.3 T. The induced rf plasma current flows in opposite toroidal directions in the ... [Phys. Fluids 23, 2301 (2008)] published Mon Jul 21, 2008.
Local instability near the vortex point of a field-reversed mirror
William A. Newcomb
A study is made of the curvature-driven magnetohydrodynamic instability in the neighborhood of the vortex point of a simple field-reversed magnetic-mirror system, with a purely poloidal magnetic field. The linearized magnetohydrodynamic equation of motion for localized modes in that neighborhood is ... [Phys. Fluids 23, 2296 (2008)] published Mon Jul 21, 2008.
Rippling of the critical surface by four-wave processes in a laser-irradiated plasma
Wee Woo, J. S. DeGroot, and C. Barnes
Rippling of the critical surface is investigated by a four-wave process in which two electromagnetic waves are scattered by an ion perturbation for very high intensities in a laser-irradiated plasma. The mechanism is the parametric oscillating two-stream instability for the electromagnetic waves. Th ... [Phys. Fluids 23, 2291 (2008)] published Mon Jul 21, 2008.
Enhanced transport in tokamaks due to toroidal ripple
Allen H. Boozer
A method for evaluating transport in nonsymmetric systems is developed and applied to a previously little studied ripple collisionality regime of tokamaks. This collisionality regime, the ripple plateau, is the regime of primary importance both for present day and reactor scale tokamaks. The results ... [Phys. Fluids 23, 2283 (2008)] published Mon Jul 21, 2008.
Stability of the noncircular screw pinch
G. Miller
The magnetohydrodynamic stability of a slightly noncircular screw pinch with arbitrary cross-sectional shape is investigated analytically and numerically using two models: the surface-current model and the force-free model. For the surface-current model the noncircular correction to the instability ... [Phys. Fluids 23, 2277 (2008)] published Mon Jul 21, 2008.
A two-term approximation for growth rates of a guiding center screw pinch
Thomas E. Cayton, George Vahala, and D. C. Barnes
The guiding center plasma description of an isotropic, collisionless plasma is used to study the linear stability of the diffuse screw pinch in the special case when the poloidal magnetic field component is small compared with the axial magnetic field component. A two-term approximation for growth r ... [Phys. Fluids 23, 2270 (2008)] published Mon Jul 21, 2008.
Nonlinear space-charge waves on cylindrical electron beams and plasmas
Thomas P. Hughes and Edward Ott
Nonlinear space-charge waves in a strongly magnetized cylindrical plasma are investigated. Soliton and periodic wave solutions are obtained. For the case of an intense unneutralized electron beam, a significant decrease in the phase velocity of the slow space-charge wave is found at large amplitudes ... [Phys. Fluids 23, 2265 (2008)] published Mon Jul 21, 2008.
Self-modulation of ion Bernstein waves
J. R. Myra and C. S. Liu
A self-modulation equation for coherent ion Bernstein waves is derived by a multiple-time-scale, perturbative expansion of the Vlasov equation. The dominant nonlinearity acting on the waves is shown to be the nonlinear ion gyrofrequency shift. The waves obey a version of the nonlinear Schrodinger eq ... [Phys. Fluids 23, 2258 (2008)] published Mon Jul 21, 2008.
Wave modulation in a nonlinear dispersive medium
Y. C. Kim, L. Khadra, and E. J. Powers
A model describing the simultaneous amplitude and phase modulation of a carrier wave propagating in a nonlinear dispersive medium is developed in terms of nonlinear wave-wave interactions between the sidebands and a low frequency wave. It is also shown that the asymmetric distribution of sidebands i ... [Phys. Fluids 23, 2250 (2008)] published Mon Jul 21, 2008.
Drift-wave eigenmodes in toroidal plasmas
Liu Chen and C. Z. Cheng
The eigenmode equation describing ballooning drift waves in toroidal plasmas is investigated both analytically and numerically. Two branches of eigenmodes are identified. One is slab-like and the other is a new branch induced by finite toroidal coupling. The slab-like eigenmodes correspond to unboun ... [Phys. Fluids 23, 2242 (2008)] published Mon Jul 21, 2008.
Finite bandwidth induced stochasticity in a magnetic mirror
C. R. Menyuk and Y. C. Lee
The electrostatic fluctuation spectrum in a magnetic mirror always has some finite bandwidth. The role of a finite bandwidth in destroying the superadiabatic motion of ions has been explored. It is found that virtually any bandwidth is sufficient to destroy the resonant island regions in velocity sp ... [Phys. Fluids 23, 2225 (2008)] published Mon Jul 21, 2008.
Particle and energy end loss from a collisionless plasma
Edward H. Klevans and S. Peter Gary
A one-dimensional free-flow kinetic model is used to study the axial ion losses from a linear theta pinch under collisionless conditions. The effects of a simple mirror model are included. The loss due to ion thermal flux is shown to be much smaller than the total ion kinetic energy flux loss, there ... [Phys. Fluids 23, 2219 (2008)] published Mon Jul 21, 2008.
A confinement theorem for nonneutral plasmas
T. M. O'Neil
A plasma consisting solely of particles of a single species is initially in the shape of a long column. It is confined by an axial magnetic field in a region of space bounded by a perfectly conducting and perfectly absorbing cylindrical wall. Conservation of angular momentum and conservation of ener ... [Phys. Fluids 23, 2216 (2008)] published Mon Jul 21, 2008.
Monte Carlo hybrid modeling of electron transport in laser produced plasmas
Rodney J. Mason
A new Monte Carlo hybrid scheme for the transport of electrons in laser produced plamas is described in detail. Comparison is made with alternate schemes. The hot electrons are followed as collisional particles-in-cell. The cold electrons are a donor-cell fluid. The self-consistent E field is comput ... [Phys. Fluids 23, 2204 (2008)] published Mon Jul 21, 2008.
Simulations of the runaway electron distributions
J. C. Wiley, Duk-In Choi, and Wendell Horton
The time evolution of the electron distribution function is followed from an initial Maxwellian to the quasi-steady-state runaway distribution as a function of E/E and Z using a new two-dimensional FokkerPlanck code. The electron distributions are used to determine the runaway production rate, the c ... [Phys. Fluids 23, 2193 (2008)] published Mon Jul 21, 2008.
Transport equations for fast electrons in a moving Newtonian fluid
J. Robert Buchler
The equations for the transport of relativistic electrons are derived inclusive of all terms of order (v/c). The equations are valid in all regimes, from diffusion to streaming. The moments of the electron distribution function, as well as the electron velocities, are measured in the fluid frame. No ... [Phys. Fluids 23, 2189 (2008)] published Mon Jul 21, 2008.
Stimulated Brillouin rescattering
T. Speziale, J. F. McGrath, and R. L. Berger
Rescattering of stimulated Brillouin scattered light is investigated. The net reflection coefficient for light scattered by a plasma slab is calculated and compared with the single scatter result. ... [Phys. Fluids 23, 1275 (2008)] published Mon Jul 21, 2008.
Nonlinear estimates of Brillouin scatter in plasma
W. L. Kruer
Simple models are used to provide nonlinear estimates of Brillouin scatter in several complementary regimes. Some applications to laser plasma interactions are given. ... [Phys. Fluids 23, 1273 (2008)] published Mon Jul 21, 2008.
Exact Vlasov equilibria for field-reversing rings
Paul J. Channell
A technique is developed for finding exact Vlasov equilibria for field-reversing rings. An infinite class of equilibria can be generated in which the plasma is confined to a finite region of space. A variety of ring cross sectional shapes can be found. ... [Phys. Fluids 23, 1263 (2008)] published Mon Jul 21, 2008.
Decay of a lower-hybrid wave to two lower-hybrid waves
Allan Reiman
The threshold and initial evolution for the decay of a lower-hybrid wave to two lower-hybrid waves are determined. Included are the effects of convective losses in a three-dimensional lower-hybrid resonance cone geometry and the effects of inhomogeneity appropriate to lower-hybrid heating in a tokam ... [Phys. Fluids 23, 1254 (2008)] published Mon Jul 21, 2008.
Mode conversion of lower-hybrid waves
V. S. Chan, S. C. Chiu, and G. E. Guest
In an inhomogeneous plasma, partial conversion of lower-hybrid waves to ion plasma waves can occur for a range of plasma parameters, even in the absence of a reflection layer. Nonetheless, mode conversion may be significantly reduced if the plasma is sufficiently dissipative. If electron Landau damp ... [Phys. Fluids 23, 1250 (2008)] published Mon Jul 21, 2008.
Effect of flux-limited thermal conduction on the jump conditions of the laser-plasma critical surface
F. J. Mayer, R. L. Berger, and Claire E. Max
The effects of flow, radiation pressure, and flux-limited thermal conduction on the plasma profile near the critical surface are examined. When the absorbed flux is deposited locally and the thermal conduction is inhibited, the density profile and plasma flow are determined by the flux limit because ... [Phys. Fluids 23, 1244 (2008)] published Mon Jul 21, 2008.
Classical collisional theory of beam-driven plasma currents
S. P. Hirshman
A variational calculation of the current produced in a plasma by fast beam particles is presented. A new energy polynomial expansion of the classical Spitzer function is obtained and used to derive an accurate analytic expression for the beam-driven current j, which includes the effects of electron- ... [Phys. Fluids 23, 1238 (2008)] published Mon Jul 21, 2008.
Particle stochasticity due to magnetic perturbations of axisymmetric geometries
H. E. Mynick and John A. Krommes
The quasi-linear theory of collisionless test particle diffusion in stochastic magnetic fields is extended to include the effects of finite gyroradius rho and particle drifts (including magnetic trapping). A canonical framework is used, in which both the criterion for onset of stochasticity and the ... [Phys. Fluids 23, 1229 (2008)] published Mon Jul 21, 2008.
Nonlinear saturation and thermal effects on the free electron laser using an electromagnetic pump
A. T. Lin and J. M. Dawson
The production of visible laser radiation by a low energy relativistic electron beam (MeV) is most readily accomplished through the use of a high frequency (far infrared) electromagnetic pump (lambda=lambda/4gamma); such radiation can be generated by reflecting the radiation the relativistic electro ... [Phys. Fluids 23, 1224 (2008)] published Mon Jul 21, 2008.
Ponderomotive laser-plasma effects subject to strong magnetic fields and collisions
I. P. Shkarofsky
The self-generated magnetic field in laser-plasma interactions is allowed to be sufficiently strong so that the cyclotron frequency exceeds the electron-ion collision frequency. Kinetic theory is applied to determine the ponderomotive terms in the transport coefficients of current flow, heat flow, a ... [Phys. Fluids 23, 1215 (2008)] published Mon Jul 21, 2008.
Kinetic equations for low frequency instabilities in inhomogeneous plasmas
Thomas M. Antonsen, Jr. and Barton Lane
Kinetic equations for low frequency, short perpendicular wavelength, electromagnetic perturbations in an inhomogeneous, magnetically confined plasma are developed. The analysis makes use of the recently developed high toroidal mode number expansion to reduce the lowest-order system of equations to a ... [Phys. Fluids 23, 1205 (2008)] published Mon Jul 21, 2008.
Wave-particle transport from electrostatic instabilities
S. Peter Gary
The second-order theory for electrostatic microinstabilities driven by currents both across and parallel to a uniform magnetic field in a Vlasov plasma is considered. Both electrons and ions are taken as magnetized, and propagation is in the plane defined by the drift velocities and the magnetic fie ... [Phys. Fluids 23, 1193 (2008)] published Mon Jul 21, 2008.
Electron temperature gradient driven microtearing mode
N. T. Gladd, J. F. Drake, C. L. Chang, and C. S. Liu
The linear stability theory of an electron temperature gradient driven microtearing mode, an instability recently proposed as a possible cause for anomalous electron thermal transport in tokamaks, is considered. The theory is electromagnetic and is carried out within the context of a slab model with ... [Phys. Fluids 23, 1182 (2008)] published Mon Jul 21, 2008.
Two-dimensional analysis of trapped-ion eigenmodes
R. Marchand, W. M. Tang, and G. Rewoldt
The first fully two-dimensional eigenmode analysis of the trapped-ion instability in an axisymmetric toroidal geometry is presented. The poloidal structure is taken into account by Fourier-expanding the perturbed electrostatic potential, phi, in theta. Assuming that the perturbation varies mildly ov ... [Phys. Fluids 23, 1164 (2008)] published Mon Jul 21, 2008.
Oblique collision of ion-acoustic solitons
Frederic Ze, Noah Hershkowitz, and Karl E. Lonngren
Identical spherical outgoing ion-acoustic solitons are launched from two separated spheres. The solitons collide in the plane midway between the spheres. The collision is inelastic in that a soliton-like object is created during the collision. Many of the characteristics of the interaction of the so ... [Phys. Fluids 23, 1155 (2008)] published Mon Jul 21, 2008.
Bifurcation and ''strange'' behavior in instability saturation by nonlinear three-wave mode coupling
J.-M. Wersinger, J. M. Finn, and Edward Ott
A simple model of nonlinear saturation of an unstable mode is studied. The model consists of the resonant three-wave coupling equations with the highest frequency wave linearly unstable and the two lower frequency waves damped. As the damping of the stable waves is increased, the solutions go throug ... [Phys. Fluids 23, 1142 (2008)] published Mon Jul 21, 2008.
Observation of shock-generated turbulence in a magnetized plasma by CO[sub 2] laser scattering
S. H. Gold, A. W. DeSilva, and J. D. Huba
Small angle CO laser scattering is used to sense density fluctuations produced by microinstabilities in a collisionless plasma driven by a magnetic implosion in a high voltage theta pinch. Turbulent density fluctuations are measured at a wavelength near the Debye length within and behind the current ... [Phys. Fluids 23, 1132 (2008)] published Mon Jul 21, 2008.
A channel model for long arcs in air
Don J. Latham
The results of an empirically based model for a vertical direct current arc discharge in 1 atm air are presented. The arc is found to be quasi-steady state for currents between 20 and 5000 A. There are two distinct core temperature ranges, one near 7000 degrees K and the other near 12 000 degrees ... [Phys. Fluids 23, 1710 (2008)] published Mon Jul 21, 2008.
Study of x-ray emissions from a copper plasma produced by a laser
B. K. Sinha and N. Gopi
Using a 50 MW, 60 nsec ruby laser, variation of x-ray emissions from a copper plasma with laser flux has been studied in a purely collisional regime for laser-plasma interaction. Scaling laws of x-ray intensity and plasma temperature versus laser flux are reported. Relative contributions of recombin ... [Phys. Fluids 23, 1704 (2008)] published Mon Jul 21, 2008.
Observations of fluctuating omega [sub p] emission in Alcator tokamaks
I. H. Hutchinson and S. E. Kissel
Measurements are presented of fluctuating millimeter-wave radiation from the Alcator tokamaks. Its characteristics are (1) rapid modulation, approaching 100% with rise time 34 [mu]sec, (2) very narrow line width, <5 GHz at the plasma frequency, and (3) extremely large intensity, up to 200 times ther ... [Phys. Fluids 23, 1698 (2008)] published Mon Jul 21, 2008.
Bifurcation of sharp boundary beta =1 multipole equilibria
Ross L. Spencer
The bifurcation of sharp boundary magnetohydrodynamic equilibria in linear multipoles of arbitrary order is studied using the hodograph method. In the low pressure limit, simple formulae are obtained for the shapes of multipole cusp equilibria. In the high pressure limit the equilibria are found to ... [Phys. Fluids 23, 1691 (2008)] published Mon Jul 21, 2008.
Resonant absorption by a magnetic plasma at a rippled critical surface
F. David and R. Pellat
When laser light is incident on a plasma, unstable filamentary structures may develop, producing a rippling of the critical surface. Such density ripples lead to resonant absorption of normally incident, p-polarized laser light. In order to compute the absorption coefficient, the eikonal approximati ... [Phys. Fluids 23, 1682 (2008)] published Mon Jul 21, 2008.
Parametric excitation of ion quasi-mode by the pump near the ion cyclotron frequency
M. Ono, M. Porkolab, and R. P. H. Chang
Parametric excitation of a nonresonant ion quasi-mode in a low density (i.e., omega[approximate]Omega) plasma is observed when the pump frequency is omega>~2Omega. From the interferometry measurement, the lower sideband is identified to be the cold lower hybrid wave and the low-frequency mode is sho ... [Phys. Fluids 23, 1675 (2008)] published Mon Jul 21, 2008.
Parametric decay into ion cyclotron waves and drift waves in multi-ion species plasma
M. Ono, M. Porkolab, and R. P. H. Chang
Parametric decay processes near the ion cyclotron frequency are investigated experimentally and theoretically in multi-ion species plasmas. The relevant theoretical dispersion relation of the parametric coupling is derived, including the ion drift motion. Experimental data obtained in the Princeton ... [Phys. Fluids 23, 1656 (2008)] published Mon Jul 21, 2008.
Stochastic ion heating by an electrostatic wave in a sheared magnetic field
Y. Gell and R. Nakach
Effects of the shear of the magnetic field on the stochastic acceleration of ions due to an electrostatic wave with a frequency in the lower-hybrid range are considered. An appropriate Hamiltonian formalism is used to analyze the equations of motion numerically and theoretically. The surface of sect ... [Phys. Fluids 23, 1646 (2008)] published Mon Jul 21, 2008.
A model for laser driven ablative implosions
Claire E. Max, C. F. McKee, and W. C. Mead
A theoretical model is presented describing the spatial structure and scaling laws of laser driven ablative implosions. The effect of inhibited electron thermal transport is explicitly included. The theory is in excellent agreement with results from a computer hydrodynamics code, under conditions wh ... [Phys. Fluids 23, 1620 (2008)] published Mon Jul 21, 2008.
Theoretical multiple beam overlap from channel transport of intense particle beams
Thomas P. Wright and John A. Halbleib Sr.
The overlap of intense particle beams transported in current-carrying plasma channels for inertial confinement fusion has been studied. Basic geometric considerations suggest an upper bound on the current density gain of N/4 due to the overlap of N uniform beams that are transported to the overlap r ... [Phys. Fluids 23, 1603 (2008)] published Mon Jul 21, 2008.
Theory of the resistive hose instability in relativistic electron beams
Han S. Uhm and M. Lampe
A theory of the resistive hose instability is developed for an infinitely long relativistic electron beam propagating parallel to an applied axial magnetic field. Complete space-charge neutralization by the ambient plasma and paraxial flow (p>~>~p+p) are assumed. An integro-differential eigenvalue e ... [Phys. Fluids 23, 1574 (2008)] published Mon Jul 21, 2008.
Reflection and absorption of electromagnetic waves obliquely incident on a half-space relativistic plasma
Kaya Imre and Ercument Ozizmir
Reflection and absorption characteristics of electromagnetic waves obliquely incident upon a half-space relativistic Vlasov plasma are investigated. Numerical results comparing the properties of the s- and p-polarized waves are given. It is shown that the response of plasma can be best understood by ... [Phys. Fluids 23, 1566 (2008)] published Mon Jul 21, 2008.
Helical relativistic electron beam Vlasov equilibria
H. M. Lai
Three existing helical relativistic electron beam models are discussed and compared. Both Yoshikawa's and Lawson's models are shown to be derivable from appropriate Vlasov equilibria. A new helical Vlasov equilibrium with energy spread is presented and studied. Unlike Auer's axial current model in w ... [Phys. Fluids 23, 1559 (2008)] published Mon Jul 21, 2008.
Dielectric response in guiding center plasma
John A. Krommes and Philippe Similon
The dielectric function for a guiding center plasma is derived from the direct-interaction approximation. For the special case of thermal equilibrium, the result agrees with, although it is more detailed than, an earlier calculation of Taylor. An explicit formula for the collision operator Sigma[pri ... [Phys. Fluids 23, 1553 (2008)] published Mon Jul 21, 2008.
Radiation from a localized Langmuir oscillation in a uniformly magnetized plasma
H. P. Freund and K. Papadopoulos
The electromagnetic radiation at the first and second harmonics of the electron plasma frequency from a localized Langmuir perturbation is computed for the case of a uniformly magnetized plasma. It is assumed that the localized perturbations in both the electrostatic field and plasma density have cy ... [Phys. Fluids 23, 1546 (2008)] published Mon Jul 21, 2008.
Existence of a time-dependent heat flux-related ponderomotive effect
H. Schamel and Ch. Sack
The existence of a new ponderomotive effect associated with high-frequency waves is pointed out. It originates when time-dependency, mean velocities, or divergent heat fluxes are involved and it supplements the two effects known previously, namely, the ponderomotive force and fake heating. Two proof ... [Phys. Fluids 23, 1532 (2008)] published Mon Jul 21, 2008.
Alteration of Pfirsch--Schl[u-umlaut]ter transport in tokamaks by all four external sources
Keith H. Burrell
Tokamak energy and particle transport are calculated for a plasma in the PfirschSchluter regime containing all possible external sources: particle, momentum, heat, and heat momentum. The effect of the last source has never been considered previously; its presence makes possible simultaneous control ... [Phys. Fluids 23, 1526 (2008)] published Mon Jul 21, 2008.
Thermal diffusion of ions drifting in an electric field through a neutral gas
Ulrich Weinert
A simple perturbation theory is applied to investigate the influence of an external temperture gradient on the drift of ions moving through a neutral gas under the influence of a homogeneous electric field. Based upon the two-temperature model, an expression is given for the field-dependent thermal ... [Phys. Fluids 23, 1518 (2008)] published Mon Jul 21, 2008.
Diffusion of rarefied gas mixtures in a circular tube under the existence of pressure gradients
Tatsuo Kanki, Satoru Iuchi, and Yuji Yamamoto
A simple and general expression for nonuniform pressure diffusion of a binary mixture in a circular tube is obtained by applying locally uniform distributions of molecular velocity plus a new physical model on the molecular transport of momentum in the Knudsen layer, which is derived from the moment ... [Phys. Fluids 23, 1501 (2008)] published Mon Jul 21, 2008.
Erratum: Linearized analysis of inhomogeneous plasma equilibria: General theory [J. Math. Phys. [bold 20], 413 (1979)].
H. Ralph Lewis and Keith R. Symon
... [J. Math. Phys. 21, 599 (2008)] published Mon Jul 21, 2008.
Equation of state of a dense boron plasma by Thomas--Fermi--Dirac--Weizs[a-umlaut]cker molecular dynamics
J.-F. Danel, L. Kazandjian, and G. Zerah
Simulations consistently combining classical molecular dynamics applied to nuclei and ThomasFermiDiracWeizsacker theory applied to electrons are used to calculate both pressure and internal energy of a boron plasma along the isotherms T=1 and 4 eV. A regularized pseudopotential must be used to repr ... [Phys. Plasmas 15, 072704 (2008)] published Fri Jul 18, 2008.
Arbitrary amplitude double layers in warm dust kinetic Alfv[e-acute]n wave plasmas
Runmoni Gogoi and Nirupama Devi
Large amplitude electrostatic structures associated with low-frequency dust kinetic Alfvenic waves are investigated under the pressure (temperature) gradient indicative of dust dynamics. The set of equations governing the dust dynamics, Boltzmann electrons, ions and Maxwell's equation have been redu ... [Phys. Plasmas 15, 074504 (2008)] published Fri Jul 18, 2008.
Variance reduction in computations of neoclassical transport in stellarators using a delta f method
K. Allmaier, S. V. Kasilov, W. Kernbichler, and G. O. Leitold
An improved deltaf Monte Carlo method for the computation of neoclassical transport coefficients in stellarators is presented. Compared to the standard deltaf method without filtering, the computing time needed for the same statistical error decreases by a factor proportional to the mean free path t ... [Phys. Plasmas 15, 072512 (2008)] published Fri Jul 18, 2008.
Trapped particles by large-amplitude waves in two-dimensional Yukawa liquids
Lu-Jing Hou and Alexander Piel
In recent experiments of strongly coupled complex plasmas (SCCPs), trapping-like phenomena of micro-sized dust particles were observed during propagation of large-amplitude dust-density waves. A small number of particles were observed being trapped and carried along with the waves. In the present pa ... [Phys. Plasmas 15, 073707 (2008)] published Fri Jul 18, 2008.
Compression of trapped positrons in a single particle regime by a rotating electric field
R. G. Greaves and J. M. Moxom
Positrons confined in a cylindrical Penning trap are compressed radially by applying a rotating electric field. Previous experiments were conducted with large numbers of positrons in the plasma state. Compression of small numbers of positrons in the single particle regime is reported for the first t ... [Phys. Plasmas 15, 072304 (2008)] published Fri Jul 18, 2008.
Spontaneous Thermal Waves in a Magnetized Plasma
D. C. Pace, M. Shi, J. E. Maggs, G. J. Morales, and T. A. Carter
Coherent temperature oscillations corresponding to thermal (diffusion) waves are observed to be spontaneously excited in a narrow temperature filament embedded in a large, but colder, magnetized plasma. The parallel and transverse propagation properties of the waves satisfy the predictions of the cl ... [Phys. Rev. Lett. 101, 035003 (2008)] published Fri Jul 18, 2008.
Ion Collection by Oblique Surfaces of an Object in a Transversely Flowing Strongly Magnetized Plasma
I. H. Hutchinson
The equations governing a collisionless obliquely flowing plasma around an ion-absorbing object in a strong magnetic field are shown to have an exact analytic solution even for an arbitrary (two-dimensional) object shape, when temperature is uniform, and diffusive transport can be ignored. The solut ... [Phys. Rev. Lett. 101, 035004 (2008)] published Fri Jul 18, 2008.
Eigenmode analysis of geodesic acoustic modes
Zhe Gao, K. Itoh, H. Sanuki, and J. Q. Dong
Geodesic acoustic modes (GAMs) are studied as plasma eigenmodes when an electrostatic potential nearly constant around a magnetic surface is applied to collisionless toroidal plasmas. Besides the standard GAM, a branch of low frequency mode and an infinite series of ion sound wavelike modes are iden ... [Phys. Plasmas 15, 072511 (2008)] published Thu Jul 17, 2008.
Dynamics of a dense laboratory plasma jet investigated using soft x-ray laser interferometry
Jonathan Grava, Michael A. Purvis, Jorge Filevich, Mario C. Marconi, Jorge J. Rocca et al.
The formation and evolution of a collisional aluminum plasma jet created by optical laser irradiation of triangular grooves with pulses of 120 ps duration at an intensity of 1 x 10 W cm were studied with experiments and simulations. Series of high-contrast soft x-ray laser interferograms obtained ... [Phys. Rev. E 78, 016403 (2008)] published Thu Jul 17, 2008.
Anisotropic scaling of magnetohydrodynamic turbulence. (arXiv:0807.3713v1 [physics.plasm-ph])
ePrint arXiv http://arXiv.org/
Geometrical description of non-linear electrostatic oscillations in relativistic thermal plasmas. (arXiv:0807.3700v1 [physics.plasm-ph])
ePrint arXiv http://arXiv.org/
Nonlinear finite-Larmor-radius effects in reduced fluid models. (arXiv:0807.3680v1 [physics.plasm-ph])
ePrint arXiv http://arXiv.org/
Conditions for Existence of Compact Stationary Relativistic Beam Torus. (arXiv:0807.3620v1 [physics.plasm-ph])
ePrint arXiv http://arXiv.org/