Experimental Study of Electron Energization Mechanism in RF Hollow Cathode Discharge

Herein, we experimentally addressed the electron energization mechanisms of radio frequency hollow cathode in argon atmosphere. The impact of the operating conditions, including the pressure p, cathode's inner diameter D and RF voltage, on the plasma properties, such as the electron density, electron energy probability function (EEPF) and electron energization mechanisms was investigated. The results show that the pD product and RF voltage all have a major impact on the electron energization mechanisms, and that the hollow cathode generates higher electron density than the parallel cathode does. To be specific, the plasma density, generated by the hollow cathode, increased with the increases of RF voltage and pressure; and an increased pD gradually turned the stochastic heating of only high energy electrons into ohmic heating of all electrons. Besides, an increasing RF voltage progressively changed the electron energization mechanism from ohmic heating into stochastic heating.