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

Journal Article · Fri Dec 31 23:00:00 EST 1993 · 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), Journal Name: Physics of Plasmas; (United States) Vol. 1:1; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

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