Study on modification of power supply system for long pulse operation on JT-60 positive ion-based NBI

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

The JT-60 positive ion-based NBI (P-NBI) system is required to extend the pulse duration from 30 s to 100 s for JT-60SA, which is the modification of JT-60U to a fully superconducting coil tokamak. The JT-60SA NBI system will have 12 P-NBI units, each of which will inject 2 MW at 85 keV. The present power supply system is to be upgraded to operate for 100 s with minimum modification. The modification of the power supply has been studied in view of the protective characteristic and the thermal capacities of main power supply components. The design study is based on the results of the first modification of 30 s operation which was done in 2003. It has been confirmed that the long pulse operation of 100 s is possible by with partial modification of the power supply components such as enhancement of the water-cooled resistance of the acceleration power supply.