Temperature Stabilization of the Klystron Cooling Water at the KOMAC

Abstract

A total of nine klystrons each with a high peak power are used to deliver RF power to the 100 MeV proton linac at the Korea Multi-purpose Accelerator Complex (KOMAC). We found that the temperature of the cooling water to the klystron cavity was deeply related to the RF power output from the klystron when the klystron was operated either in the open loop mode or at a saturation power level. To stabilize the RF power from the klystron, we need to stabilize the cooling water’s temperature as much as possible. To keep the cooling water’s temperature constant, we used an inverter-driven cooling fan at the cooling tower with proportional integral derivative (PID) controller. Through a proper tuning of the control parameters, we could suppress the temperature fluctuation to within ±0.2 °C and stabilize the output RF power from the klystron, regardless of the ambient temperature. Details on the dependency of the output RF power on the coolant temperature and stabilization method will be given in this paper.