High-Frequency Instabilities in Sheaths and Fireballs

Abstract

Electron inertia causes a delay between high-frequency currents and electric fields. When the transit time of a bunch of streaming electrons equals one RF period, the electrons can enhance the field and produce oscillations. Here, electron transit-time instabilities have been observed in magnetized sheaths and fireballs. Novel fireballs trapped in a gridded hollow anode have been developed. These produce large-amplitude RF oscillations.