An experimental study of argon plasma in aluminium coated plasma chamber of 6.4 GHz ECR ion source at VECC

A multiply charged two stage 6.4 GHz Electron Cyclotron Resonance (ECR) ion source was developed in VECC a few years ago. It was modified in phases based on magnetic topology, microwave feed and external supply of cold electrons to improve the ion production performance. In the present experimental study electron repeller biased disc as Langmuir probe was used to understand the electron repeller effect in aluminum coated plasma chamber of 6.4 GHz ECR ion source. Here, the repeller aluminium disc placed on the axis of the plasma chamber has been biased with respect to the floating plasma chamber. Probe current and ion current of Ar+ were measured at different bias voltages and currents for a particular discharge condition. The discharge condition was varied by changing only microwave power heating the plasma but the mirror magnetic field and gas feed remained unchanged throughout the experiment