Modification of power supplies in the negative-ion-based NBI system for a 100s operation in JT-60SA

Usui, Katsutomi; Noto, Katsuya; Kawai, Mikito; Oga, Tokumichi*; Ikeda, Yoshitaka

The JT-60 negative ion-based NBI (N-NBI) system is required to extend the pulse duration from 30s to 100s in JT-60SA that is the modified JT-60U with full superconducting coils. The JT-60SA N-NBI system will have 2 ion sources, each of which will inject 5 MW at 500 keV. The present power supply system should be upgraded to operate for 100s with minimizing the modification of existing components. The protective characteristic and thermal capacities of the power supply components were assessed based on the experience of the modification for the 30s operation in 2003. The acceleration power supply is to be modified with combination of existing Gate Turnoff Thyristors (GTO) and Injection Enhanced Gate Transistors (IEGT) added newly. Five power supplies for a plasma production in the negative ion sources are to be modified by increasing the capacities of the partial resistance and cooling systems. These modifications can allow the long pulse operation of 100 for JT-60SA N-NBI system.