Theory of the acoustic instability and behavior of the phase velocity of acoustic waves in a weakly ionized plasma

O. S. Torosyan, A. R. Mkrtchyan

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The amplification of acoustic waves due to the transfer of thermal energy from electrons to the neutral component of a glow discharge plasma is studied theoretically. It is shown that, in order for acoustic instability (sound amplification) to occur, the amount of energy transferred should exceed the threshold energy, which depends on the plasma parameters and the acoustic wave frequency. The energy balance equation for an electron gas in the positive column of a glow discharge is analyzed for conditions typical of experiments in which acoustic wave amplification has been observed. Based on this analysis, one can affirm that, first, the energy transferred to neutral gas in elastic electron-atom collisions is substantially lower than the threshold energy for acoustic wave amplification and, second, that the energy transferred from electrons to neutral gas in inelastic collisions is much higher than that transferred in elastic collisions and thus may exceed the threshold energy. It is also shown that, for amplification to occur, there should exist some heat dissipation mechanism more efficient than gas heat conduction. It is suggested that this may be convective radial mixing within a positive column due to acoustic streaming in the field of an acoustic wave. The features of the phase velocity of sound waves in the presence of acoustic instability are investigated.

Original languageEnglish
Pages (from-to)346-354
Number of pages9
JournalPlasma Physics Reports
Volume29
Issue number4
DOIs
Publication statusPublished - Apr 2003
Externally publishedYes

Fingerprint

acoustic instability
phase velocity
acoustics
wave amplification
neutral gases
energy
glow discharges
thresholds
sound amplification
acoustic streaming
electrons
inelastic collisions
sound waves
thermal energy
conductive heat transfer
electron gas
elastic scattering
cooling
collisions
gases

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Condensed Matter Physics

Cite this

Theory of the acoustic instability and behavior of the phase velocity of acoustic waves in a weakly ionized plasma. / Torosyan, O. S.; Mkrtchyan, A. R.

In: Plasma Physics Reports, Vol. 29, No. 4, 04.2003, p. 346-354.

Research output: Contribution to journalArticle

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