Development of a water load for a Ka-band 10 kW continuous-wave gyrotron in an ECR ion source system

A gyrotron is used as a microwave power source in an electron-cyclotron-resonance (ECR) ion source system. In order to test the gyrotron, which operates at a frequency of 28 GHz in the continuous-wave (CW) mode, the Korea Basic Science Institute (KBSI) developed a water load that absorbed up to 10 kW of power. The water load consists of an aluminum jacket, a quartz window, and a waveguide. A distilled water flow of 13 L/min, sealed with the quartz window, is used as the absorbent. At 28 GHz, the S 11 parameter and the voltage standing-wave ratio (VSWR) of the water load design were calculated to be less than −30 dB and 1.05, respectively. In practical experiments, the increase in the water’s temperature was approximately 10 °C at the highest power.