A Mini-Marx Generator Powered by a Cockcroft–Walton Voltage Multiplier

Abstract

A Marx generator generates a high-voltage (HV) pulse by charging two or more capacitors in parallel and then suddenly connecting them in series. In principles, a comparatively lower voltage dc power supply has to be used for the charging to achieve the desired HV. However, a moderate dc HV power supply is still quite expensive and bulky but not in full-time usage. In this work, a mini-Marx generator powered by a Cockcroft–Walton (CW) voltage multiplier has been proposed to form a more efficient, compact, but affordable configuration of pulsed HV power sources. For generating an HV in a range of 20–150 kV with the mini-Marx generator consisting of eight stages, a CW multiplier operating up to 3–20 kV is required. Numerical simulations using PSpice have been performed for validating the concept. For demonstration, a prototype of the 22-stage CW-powered four-stage mini-Marx has been built and tested with an ac voltage of 110 V at 60 Hz. In the experiment, the CW generator can reach 3.6 kV to power the mini-Marx, delivering an HV of 12.7 kV, consistent with the PSpice modeling. With an ac household voltage of 220 V at 60 Hz, a dc voltage of 5.2 kV can be obtained from the CW to charge an eight-stage mini-Marx generator, achieving an output voltage of 33 kV to drive a field emission-based X-ray source. The proposed CW powered mini-Marx generator is general and can be used as a compact pulsed voltage supply for some portable devices.