Optical measurement of plasma oscillations in a Hall thruster

Plasma oscillation phenomena in a Hall thruster were experimentally investi gated. The Nagoya University Hall Thruster was tested. Several oscillation frequencies have been observed in a discharge current and in optical emissi ons from the acceleration channel, and the fluctuations were found propagat ing in the longitudinal and azimuthal directions in the channel. The oscill ations were classified into the ionization oscillation, transit-time oscill ation and electron drift oscillation, according to their frequency. The mec hanism of each oscillation has been theoretically discussed.