Characteristics of RF H^- ion source by using FET power source

Characteristics of radio frequency(rf) plasma production are investigated using a FET inverter power supply as an rf generator. The matching circuit in the inverter system is simple compared to a conventional 50 Ohm matching system and only an imaginary part of the impedance of rf transmission should be matched by adjusting operating frequency or capacitance of the circuit. An electron density over 10¹⁸m^-3 is produced in argon plasma with lkW rf power. Lower densities are obtained in helium and hydrogen plasmas compared to the argon plasma. Effect of axial magnetic field in driver region is examined. Electron density more than 10¹⁸m^-3 is obtained at the hydrogen gas pressure around lPa with the help of the axial magnetic field.