Plasma potential diagnosis using an emissive probe made of molybdenum

The space potentials of microwave electron cyclotron resonance (MW-ECR) plasmas with different discharge powers are diagnosed using an emissive probe made of molybdenum. The simulation of the molybdenum filament temperature at different heating currents reveals that the molybdenum emissive probe can reach ∼2000 K when generating appreciable electron emission, which is about 300 K lower than that of a tungsten emissive probe (∼2300 K), demonstrating the advantage of the molybdenum emissive probe in operating at a lower temperature. In addition, the contrast diagnosis results of MW-ECR plasmas using the molybdenum emissive probe with different diagnostic methods show that the plasma potentials determined by the improved inflection point method and the hot probe with zero emission limit method are in close agreement. In contrast, the plasma potentials obtained by the floating point method are consistently underestimated with a relative difference of about 3%.