Development of compact high voltage switched mode power supply for microwave plasma sources supply for low pressure plasma

Abstract

Although microwave induced plasmas are well known as high efficiency plasma sources, their uses in laboratories are limited since the microwave power systems are complicated and expensive. The output power of commercially available low-cost microwave ovens is fixed and discontinuous resulting from the high voltage doubler topology of the magnetron tube power supply. In this paper, a high voltage switched mode power supply of forward topology has been developed for continuous microwave power radiation. The forward converter can generate a no-load high voltage output maximum of 7 kV. When driving the magnetron tube, the microwave output power could be varied from 0 to 35 W while the high voltage output level was constantly regulated at -3.4 kV. A microwave induced plasma system was setup to investigate the plasma produced. A low pressure argon plasma was produced with only 2 W over a wide range of pressures.