  In this study, wall ion loss and erosion rate are evaluated in the RAIJIN
thruster. The novelty of this work is the detailed analysis of measured
guard-ring (metallic channel wall) current, which enables a fast evaluation of
the wall ion loss and erosion rate. The current-voltage characteristics of the
guard-ring current indicate that the sheath on the guard rings is in the ion
saturation regime and that the guard-ring current can be used as a wall ion
flux indicator. The experimental results demonstrate that the wall ion loss can
be significantly reduced in the magnetic configuration of RAIJIN thrusters with
the acceleration zone shifting.
