Thermal Tuning System for PEFP DTL Resonant Frequency Control

Abstract

The Proton Engineering Frontier Project (PEFP) has been tinder development to establish a 100 MeV proton accelerator complex in Korea. As a front part of the 100-MeV machine, 20-MeV proton accelerator systems were installed and tested at the site of the Korea Atomic Energy Research Institute (KEARI). The PEFP accelerator structures, such as the drift tube linac (QTL), require a water-cooling-system-based thermal tuning system to regulate the resonant frequency (rf) of the drift tube (DT) cavity to 350 MHz. We have designed and fabricated a prototype water pumping skid that has two water cooling channels of a by-passing cooling water (primary loop) and a plate heat exchanger (secondary loop). The required operating temperature can be achieved by mixing the coolants of each channel. The temperature control around the operating point could be achieved using two independent PI controllers installed in the two loops. The system set-up and test were conducted for the 20 MeV DTL systems. The results indicate that the temperature control of the drift tube cavities is available within design range of 27 6 degrees C with a precision of less than +/- 0.1 degrees C to regulate the resonant frequency of the drift tube cavities.