Ion Density and Electric-Field Perturbations Caused by an Acoustic-Wave Pulse in a Weakly Ionized Gas

Ingård, Uno

doi:10.1063/1.1691978

Cited by 2 publications

(1 citation statement)

References 4 publications

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“…When fed with a modulated discharge current containing a constant and variable component, that creates acoustic oscillations in the discharge, for which the discharge tube is an acoustic resonator. The results of experimental studies on sound generation and amplification in the discharge of some pure gases with a narrow range of measured values are given in reviews [3][4][5][6][7][8][9]. An acoustic instability caused by the interaction of acoustic waves with lowtemperature plasma results in a new plasma state, called acoustoplasma.…”

Section: Introductionmentioning

confidence: 99%

Control of Co2 Laser Power by Acoustic Fields

Abrahamyan¹,

Chilingaryan²

2019

REFFIT

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The present study investigates the optimization of the operation of the CO2 laser in the acoustoplasma mode (i.e., dependence of the laser radiation power on the composition of the working mixture, pressure, value of the direct component of the discharge current, frequency, and modulation depth). A three-dimensional dependence on the frequency and modulation depth of the discharge current is experimentally obtained for the normalized efficiency of the conversion of the electric power supplied to the discharge tube into laser power. The maximum gain when transition to the acoustoplasma mode exceeds 2.5 times. The optimum depth of the discharge current modulation is 0.5–0.7. The laser radiation power modulation caused by the discharge current modulation is measured. Laser power is not modulated at modulation frequencies of current >1 kHz. Meanwhile, at current modulation frequencies <0.5 kHz, the modulation depth of the laser radiation power nonlinearly depends on the modulation depth of the discharge current and has a threshold character. The modulation depth of the laser radiation power is associated with the creation of an acoustoplasma and not simply with the discharge current modulation.

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Section: Introductionmentioning

confidence: 99%

Control of Co2 Laser Power by Acoustic Fields

Abrahamyan¹,

Chilingaryan²

2019

REFFIT

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Acoustic Wave Propagation in a Gas Discharge

Schulz¹

1969

The Physics of Fluids

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When ordinary sound propagates in a weakly ionized gas, the wave motion of neutral particles controls that of charge carriers. The ion-density, electric-field, and electron-temperature responses to a given gas-density perturbation are calculated by means of linearized hydrodynamic equations for the case of wave propagation along the axis of a discharge. The equations include ionizing collisions, ambipolar diffusion, wall recombination, and collisions leading to intercomponent momentum and energy transfer. Because of competing effects of ions and electrons, no observable wave amplification can result from intercomponent momentum transfer. In addition to previously reported consequences of elastic collisions, the calculated dispersion relation contains an amplification term characterized by a time constant τν which is approximately the reciprocal ionization frequency (per electron) times the gas-to-plasma pressure ratio.

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Ion Density and Electric-Field Perturbations Caused by an Acoustic-Wave Pulse in a Weakly Ionized Gas

Abstract: A weak shock wave in a weakly ionized gas is shown to produce ion density and electric-field perturbations with shock “widths” approximately equal to (Te/Tn)l, where l is the mean free path in the neutral gas and (Te/Tn) is the electron-to-neutral-gas temperature ratio.

Cited by 2 publications

References 4 publications

Control of Co2 Laser Power by Acoustic Fields

Control of Co2 Laser Power by Acoustic Fields

Acoustic Wave Propagation in a Gas Discharge

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