Generation of pulse-modulated induction thermal plasma at atmospheric pressure

The radio frequency induction thermal plasma of sufficiently high electric power for materials processing has been successfully generated with a pulsemodulated operating condition. A solid-state amplifier, which supplies the electric power with a nominal frequency of 1 MHz, was employed for the pulsing plasma generation. The Ar-H-2 plasma was generated at a high power level of 17 kW at atmospheric pressure. Typically, the plasma remained stable until the pulse duty factor went down to 30%, when the period of the high power level was 5 ms and the low power level was about 6 kW. (C) 1997 American Institute of Physics. [S0003-6951(97)00752-3].