Dummy Load of the MAST-U EBW System

UKAEA is installing an Electron Bernstein Wave (EBW) system on MAST-U, which aims at injecting two dual-frequency (28 and 34.8GHz) microwave beams each of up to 900kW and pulse duration of 4.5s. The system will consist of two RF sources, their power supplies, control systems, ancillary services, transmission lines, and a steerable in-vacuum quasi-optical launching system, as well as a dummy load. The primary function of the dummy load is to absorb the microwave energy in a safe and non-destructive manner from the gyrotrons when the energy is not directed at the MAST-U plasma. The load also needs to provide functionality in terms of measuring the power being absorbed by the load, which is imperative for initial testing and gyrotron acceptance.