Design of a 500 kW CW water load at 3.7 GHz for the LHCD system of SST-1 tokamak

Abstract

The LHCD (Lower Hybrid Current Drive) system of the SST-1 Tokamak is commissioned for maintaining the plasma current for prolonged periods. The system relies on 4 Klystrons (TH-2103D) to deliver 500kW CW power each at 3.7GHz to maintain plasma discharge. High power microwave absorbers/dummy loads are required to condition the klystrons at high CW power level and to protect them against reflection. This paper presents a design of a novel and indigenous high power microwave dummy load using water as an absorber. The designed load was analyzed by considering various RF, thermal and mechanical aspects and is 300mm in length. It provides excellent matching with an evaluated value of S11 of −38dB and VSWR of 1.02:1. Simulation results show that it can absorb almost 99.99% of incident power.