New monopulse plasma generation and acceleration facility for surface treatment

Abstract

The Fachgebiet Raumfahrttechnik is working on the field of hypervelocity particle accelerators based on the electrothermal and the electromagnetic principle. All these accelerators generate a hypervelocity plasma pulse that also can be used for surface treatment and modification of metals and alloys. The facilities and pulsed power sources used up to now, however, are not adapted nor optimized for the special needs of the surface treatment application. Therefore, an entire new system was designed, built and taken into operation. Besides the mere realization of all technical requirements and aspects, a major objective was the development of a user friendly industrial-like demonstrator facility. Based on the experience of pulsed power system design and surface treatment application, we implemented the mono-pulse technique using the latest developments by ABB in the field of semiconductor switches and diodes. The pulsed power supply consists of two 25 kJ modules with high power thyristors and self-blocking diodes that generate a single half-wave current pulse of up to 200 kA with a length of about 50 /spl mu/s. The paper describes the overall system with special emphasis on the pulsed power modules. The proper functioning of the electrical system was documented in extensive check-out tests. Finally, first surface modification experiments were conducted with the new facility to show its capability in this field.