Acoustohelicon Amplification in a Piezoelectric Semiconducting Plasma

Abstract

Acoustohelicon amplification in semiconducting plasmas having piezoelectric or deformation potential coupling or both (viz., n‐InSb) are investigated using the kinetic approach. The dispersion relation for phonon‐ helicon interaction is derived in slow wave approximation. In case of a convective instability the amplification occurs if the drift velocity exceeds the velocity of sound (i.e. if the electric field is greater than 102 Vm−1) while in case of an absolute instability amplification is observed if the drift velocity is smaller than the velocity of sound (electric field less than 102 Vm−1). At higher electric fields (>4.27 × 104 Vm−1) the amplification coefficient for acoustohelicon waves, obtained by the kinetic approach, shows a maximum and then starts attenuating, contrary to the hydrodynamic approach where it is always monotonously increasing. The dependence of the amplification coefficient on various plasma parameters is studied in detail. Copyright © 1994 WILEY‐VCH Verlag GmbH & Co. KGaA