Development of -1MV Surge Absorber Systems for ITER NBI

Abstract

This paper presents the development results of surge absorber system for an ITER neutral beam injector. Circuit design and insulation design were carried out to withstand 200 times breakdown at beam source. Circuit analysis considering the B-H characteristics of FINEMET core for surge absorption shows the decrease in surge current by 60% due to the developed system. The validity of the established design was demonstrated by the actual-product tests for Transmission Line 2; FINEMET core satisfied the required saturation characteristics of 0.7Vs, and also withstood the impulse voltage of 200kV loaded in the axial direction at the reduced pressure condition of 0.1MPa,abs in the SF₆ gas atmosphere.