An analytical and numerical investigation of ion acoustic waves in a two-ion plasma

Journal Article · Tue Nov 01 04:00:00 EST 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870889· OSTI ID:7121868

Vu, H X; Wallace, J M; Bezzerides, B ^[1]

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1. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

The ion acoustic dispersion relation for a plasma containing two distinct ion species is investigated over a wide range of plasma conditions. An approximate general analytic solution to the dispersion relation has been found, and is shown, by comparison to accurate numerical solutions of the individual modes, to be remarkably precise. This solution provides for the first time a systematic account of the totality of ion acoustic modes of the two-ion system. It has been found that ion acoustic modes consist of two types of modes: (a) at least one, and, at most, two weakly damped modes for which [vert bar][omega][sub I]/[omega][sub R][vert bar][much lt]1, and (b) an infinity of critically damped modes for which [omega][sub I]/[omega][sub R][congruent][minus]1. The critically damped modes are organized into two distinct categories: (a) modes for which [vert bar][omega][vert bar]/[sub K][gt][sub V][sub F] ([sub V][sub F] is the thermal speed of the fast ion species); and (b) modes for which [sub V][sub S][lt][vert bar][omega][vert bar]/[sub K][lt][sub V][sub F] ([sub V][sub S] is the thermal speed of the slow ion species). The critically damped modes with [vert bar][omega][vert bar]/[sub K][gt][sub V][sub F] are further organized into three distinct classes: (1) modes with phase speeds characterized by [sub V][sub F], (2) modes with phase speeds characterized by [sub V][sub F][sub S]/[radical][sub V] [sup 2][sub F][minus][sub V][sup 2][sub S], and (3) modes with phase speeds characterized by [sub V][sub S]. The critically damped modes with [sub V][sub S][lt][vert bar][omega][vert bar]/[sub K][lt][sub V][sub F] belong to a single class, and are characterized by [sub V][sub S]. Generally, it is found that there are one, or, at most, two modes with relatively small damping, while most of the remaining modes are too strongly damped to be physically realized. It has also been found possible to maximize ion acoustic damping by a wise choice of relative ion concentrations.

• OSTI ID: 7121868
• Journal Information: Physics of Plasmas; (United States), Journal Name: Physics of Plasmas; (United States) Vol. 1:11; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700340* -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
ANALYTICAL SOLUTION
BRILLOUIN EFFECT
COHERENT SCATTERING
DAMPING
DISPERSION RELATIONS
EQUATIONS
HEATING
ION ACOUSTIC WAVES
ION DENSITY
ION WAVES
KINETIC EQUATIONS
LASER-RADIATION HEATING
NUMERICAL SOLUTION
PLASMA HEATING
PLASMA WAVES
SCATTERING