Plasma density distribution during hollow cathode discharge

The plasma behavior of hollow cathode discharge is experimentally investigated in this work using a disk-shaped detector biased to a low negative potential. The current density is found to depend on radio frequency (RF) power, gas flow, and space range. There exists peak ion current-density at the central zone of the detector and ion density gradually decreases towards the edge of the detector. The ion current density increases when the RF power varies from 50 to 400W and the distance between the cathode nozzle and the detector decreases from 100mm to 10mm. However, the current density exhibits nonlinear relationship with increasing gas flow.