A new power supply to ignite and sustain plasma in a reactive gas generator

This paper proposes new method of providing power for igniting plasma in a toroidal reactive gas generator. Advantages of this method include simplicity of control and prevention of damage to power supply semiconductor devices. The method combines a parallel loaded capacitor series resonant topology with a wide dynamic range control. First, the proposed parallel-loaded capacitance resonant inverter replaces the more commonly used power circuit having the plasma load in parallel with the inductance. Next, the state of the art pulse-width modulated (PWM) controller is replaced by a control combining combine pulse-frequency modulation (PFM) and PWM. Implementation includes an intelligent over current protection circuit. The combination provides a robust excitation for plasma loads making rapid transitions between extremes of impedance, and achieves superior dynamic range and stability to successfully ignite, sustain, and stabilize the plasma during operation. Simulation and lab experimental results are presented and compared with a standard a 6.5 kW plasma power supply.