Parametric instabilities and turbulent heating of a plasma in the field of a fast magneto-acoustic wave

Abstract

The authors consider the parametric instability of a homogeneous plasma in a magnetic field B⃗0 and in an alternating electric field E⃗0 perpendicular to it. The electric field frequency ω0 is of the same order as the lower hybrid frequency ωLH, while the amplitude of the relative velocity of the electrons and ions u ∼ cE0/B0 is significantly less than the thermal velocity of the electrons. The authors consider the excitation of longitudinal hydrodynamic oscillations in a cold plasma and of ion sound and electron sound in a strongly non-isothermal plasma. The characteristic values of the maximum growth rate of these oscillations is of the order of ωLH.The results are presented of experiments on turbulent plasma heating by a fast magneto-acoustic wave excited by an alternating radial electric field (f0 = ωO/2π = 150 MHz, plasma density n0 = 1012 − 1013 cm−3, B0 ≤ 5 kG). Under conditions where ω0 ∼ ωLH there is rapid heating of the electrons and ions to 200 – 400 eV. The observed heating may be attributable to the excitation of a parametric instability.