MTX transport system for 140 GHz, 0.4 MW gyrotron

Summary form only given, as follows. The MTX (Microwave Tokamak Experiment) high-power transmission system is being modified for use with a Varian 140-GHz, 0.4-MW gyrotron. The gyrotron will be used for electron cyclotron heating (ECH) as well as the master oscillator for a free electron laser (FEL) amplifier driven by an induction linac. The rotating TE_15.2 whispering gallery mode generated by the gyrotron is converted to a free space beam with a Vlasov launcher. A series of five large metal optics captures the beam and transports it 36 m to a port on the MTX tokamak. The MTH code was used to calculate beam profiles at various points throughout the system and to compute the overall transmission efficiency. Microwave diagnostics for monitoring the beam include two scanning probes at the MTX port, a precision high-power load (5000 J/pulse) to measure transmitted power, a water load for the gyrotron to measure output power, and various fundamental waveguides sampling forward and reflected power on two of the optics