Maintenance and Upgrading of KEK 12-GeV PS Injector Linac for 30 Years

Abstract

Maintenance and upgrading of the KEK proton linear accelerator for 30 years are described. The linac was substantially the first Drift Tube linac in Japan. It started with pulsed quadrupole magnets, then permanent quadrupole magnets were developed for easy maintenance. The linac was upgraded from 20 MeV to 40 MeV by introducing a new accelerating tank. It was equipped with the permanent quadrupole magnets. For the old tank, control system of the quadrupole magnet power supplies were fully modified. High-power dummy loads of 200 MHz accelerating rf were improved. Trials were made to avoid slow leaks of ceramic windows that transfer rf power up to 1.5 MW to the accelerating tank. Other miscellaneous components, such as vacuum system, cooling water, pulse generators and so on, were upgraded.