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Description
A program to develop 200 kW, 1 MHz solid state high frequency power supply is initiated in a phased manner with industry. High frequency power supply is intended for plasma formation in neutral beam source or similar applications, providing high efficiency. The present high frequency power supply is configured with multiple modules of Class-D H-Bridge inverters, magnetic combiners, tuning and matching network to provide 1 MHz sinusoidal output at 50 Ω load. A prototype 5 kW power was developed and coupled with plasma to characterize the solid state concept.
Recent experimental campaign has established matching network parameters to strike and sustain hydrogen plasma with a density in the range of 10$^{15}$ to 10$^{17}$ m$^{-3}$ at 2-3 Pa and forward power of 1.2 kW @ 1 MHz. Practical result shows that the solid state design produces plasma with an optimum power factor of 0.8-0.9 over a pulse length of 60s and beyond. It has also been observed that a power factor of 0.7-0.8 is achievable without isolation transformer in the matching circuit. Experiments are useful to study the behavior of power supply in scenarios of dynamic (plasma) conditions or sudden load/off load conditions.
This paper describes the behavior of prototype 5 kW, 1 Mhz solid state power supply during the experiment. It also gives the conceptual design of a 200 kW high frequency power supply based on the inputs learned from the prototype experiment.
