I. Introduction
High voltage generation DC power are widely used in research work and industry level. It is used in scientific instruments, TV sets and CRTs, Oscilloscope, X-ray, particle accelerators, laser systems and many other applications. The method of stepping up the voltage is commonly done by a step-up transformer in an AC system. The secondary of the step-up transformer increases the voltage and decreases the current with losses occurring in the transformer. Multipliers are preferred for stepping up the voltage in DC system. Cockcroft-Walton is a voltage multiplier developed by Greinacher and later enhanced by Cockcroft and Walton intending to produce high-energy positive ion beams [4]. Cockcroft-Walton multiplier is constructed by ladder network of capacitors and diodes for generation of high voltage DC from a low input voltage i.e. 415 V, 50 Hz AC supply. It was named after John Douglas Cockcroft and Ernest Thomas Sinton Walton used to power their particle accelerator, performing the first artificial nuclear disintegration in history. Usually a high frequency switching power supply is used for feeding the Cockcroft-Walton circuit. The switching power supply may be of many designs, such as half-bridge, flyback, or forward, depending on such deciding factors as cost, performance, and designer's choice. However, the basic building blocks of an off-the-line switching power supply are the same where the AC line voltage is directly rectified and filtered to produce raw DC, which in turn is fed into a switching element where it is chopped to a high frequency square wave. The harmonic frequencies of the square wave are reduced to an acceptable level by inserting an EMI filter on the AC output line. Here, the HPHF power supply drives a 10 stage symmetrical Cockcroft-Walton voltage multiplier operating at 500 kV, 100mA.