High-Density Plasma Production in Converging Field Following a Magnetic Beach Plasma Source

Abstract

A high ion saturation current (I_is) phase, which is characterized by larger increase/decrease of I_is compared with the magnetic field variation, is observed in a converging field following an electron cyclotron resonance plasma source with a magnetic beach configuration. Plasma production rate and particle influx are considered in terms of orbits of collisionless electrons. While the ionization probability of one-pass electron is order of 0.1, the mirror trapped electron cause ionization within several or dozen bouncing. This is an essence of improved ionization rate resulting in the high I_is phase. The temporal evolution of ion saturation current observed in the experiment is well explained by the estimated plasma production rate and particle influx.