Ion Bursts in a Negative Ion Plasma

Abstract

This chapter proposes a simple method for a negative ion species measurement utilizing the ion burst. The chapter also discusses the possibility of estimation of the transient sheath width from the time-of-flight data of the ion burst. In the experiments on ion acoustic wave propagation, many researchers have observed a faster propagating signal in addition to ion acoustic waves. The velocity of the faster signal is dependent on the excitation voltages of the grid. The ion species is determined from the velocity of the ion burst. Ion species in a negative ion plasma is measured by a simple method utilizing ion bursts excited by a pulsed mesh grid. The burst velocities show agreement with the theoretical values for SF6-. Furthermore, the transient sheath width is estimated from the time-of-flight data of the ion burst. The result is qualitatively reasonable that the sheath width increases due to the effect of negative ions.