Abstract: The classification and applied circumstance of plasma were introduced and the basic laws of energy transfer for acr plasam were discussed．According to the demand of arc plasma for power supply‚ a novel large inverter power supply with soft-switching was presented and its characteristics and efficiency were studied．The results show that the inverter power supply has excellent characteristics and high efficiency‚and meets the demand of arc plasma process well．

Key words: arc plasma, energy transfer, inverter power supply