Study of Action of Unstable AIC Waves on Electrons in a Tandem Mirror Plasma from Measurement of End Loss Electrons

Abstract

An Alfven ion cyclotron (AIC) wave spontaneously excited in the central cell of the GAMMA 10 tandem mirror has strong effects on electrons. The end loss electron flux, the electron temperature and the field aligned loss power carried by these electrons increase with excitation of the AIC wave. Since electrons escape to the machine end with a good memory of the processes having in the plasma, the action of the AIC wave on electrons has been studied through measurement of end loss electrons. Response of electrons to the AIC wave is dominated by Landau damping. Electrons are accelerated by the parallel electric field of the AIC wave only when the electron thermal velocity is nearly equal to the parallel phase velocity of the excited wave. No strong action of the AIC wave on electrons is observed if this condition does not hold. A simplified calculation shows that the temporal variation of the electron temperature is the result of balance between the absorbed power through Landau damping and the field-aligned...