Understanding and improving the neutral beam injector conditioning problem
The occurrence of high voltage electrical breakdowns between the ion beam extraction grids of a high-power neutral beam injector is one of the major factors determining the performance of an injector. The tedious procedure of conditioning the electrodes in up to several thousand shots and the stressing of electrical supplies by the fast transients are two examples illustrating the need for a greater understanding of the actual origins of the high-voltage breakdown and the desire to reduce their frequency, thereby shortening the down-times of an injector. This report attempts systematically to address these questions. It starts with a survey of literature relevant to gap breakdown in the extraction optics system. Considering the various possible reasons for breakdowns, different methods for conditioning are discussed as to their potential effectiveness and with respect to the effort required. The proposed experimental work to improve the conditioning time is then described and, finally, the results obtained so far are reported.
Bibliographic Reference: Report: IPP 4/250 EN (1991) 35 pp.
Availability: Available from Max-Planck-Institut für Plasmaphysik, 8046 Garching bei München (DE)
Record Number: 199210772 / Last updated on: 1994-12-02
Original language: en
Available languages: en