Effect of electron collisions on ion-acoustic waves and heat flow

Journal Article · Sat Jan 01 00:00:00 EST 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870563· OSTI ID:5220661

Epperlein, E M ^[1]

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1. Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States)

The damping rate of ion-acoustic waves in a plasma is calculated by numerically solving the electron Fokker--Planck and cold-ion fluid equations for arbitrary electron collisionality [ital k][lambda][sub [ital ei]] and charge number [ital Z]. The damping rate reaches a maximum at [ital k][lambda][sub [ital ei]][similar to]([ital Zm][sub [ital e]]/[ital m][sub [ital i]])[sup 1/2], as predicted by fluid theory, but then remains above fluid-theory predictions for [ital k][lambda][sub [ital ei]][gt]([ital Zm][sub [ital e]]/[ital m][sub [ital i]])[sup 1/2]. This enhancement is most significant for high-[ital Z] plasmas, where the thermalization due to electron--electron ([ital e]--[ital e]) collisions is least effective. For [ital k][lambda][sub [ital ei]][much gt]1, the damping approaches the collisionless Landau limit. The isotropic-Rosenbluth-potential approximation for [ital e]--[ital e] collisions gives rise to errors of up to 10% in the damping rates. A further approximation that involves adjusting the [ital e]--[ital i] angular scattering collision strength to simulate the contribution from [ital e]--[ital e] collisions is found to be similarly accurate. In the high-[ital Z] limit, there is a strong reduction in the effective thermal conductivity [kappa] relative to the classical Spitzer--Haerm value [kappa][sub SH] for [ital k][lambda][sub [ital ei]][gt]10[sup [minus]4]. For low-[ital Z] plasmas, this reduction only becomes significant for [ital k][lambda][sub [ital ei]][gt]10[sup [minus]2]. By introducing a spatially modulated inverse-bremsstrahlung heating source and solving for the steady-state distribution function, a further reduction in the value of [kappa]/[kappa][sub SH] is obtained.

• DOE Contract Number: FC03-92SF19460
• OSTI ID: 5220661
• Journal Information: Physics of Plasmas; (United States), Vol. 1:1; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ION ACOUSTIC WAVES
DAMPING
ELECTRON COLLISIONS
BREMSSTRAHLUNG
COMPUTER CODES
DISTRIBUTION FUNCTIONS
ELECTRON-ELECTRON COLLISIONS
ELECTRON-ION COLLISIONS
FOKKER-PLANCK EQUATION
HEAT FLOW
NUMERICAL SOLUTION
PLASMA MICROINSTABILITIES
THERMAL CONDUCTIVITY
THERMALIZATION
COLLISIONS
DIFFERENTIAL EQUATIONS
ELECTROMAGNETIC RADIATION
EQUATIONS
FUNCTIONS
INSTABILITY
ION COLLISIONS
ION WAVES
PARTIAL DIFFERENTIAL EQUATIONS
PHYSICAL PROPERTIES
PLASMA INSTABILITY
PLASMA WAVES
RADIATIONS
SLOWING-DOWN
THERMODYNAMIC PROPERTIES
700340* - Plasma Waves
Oscillations
& Instabilities- (1992-)
700330 - Plasma Kinetics
Transport
& Impurities- (1992-)
700380 - Elementary & Classical Processes in Plasmas- (1992-)