Design of high power RF amplifier for 3 MW/CW transmission line test rig

India is developing 2.5 MW RF source at VSWR 2:1 in the frequency range 35-65 MHz for ITER project. Eight such RF sources will generate total 20 MW of RF power for plasma heating and current drive. A large number of high power transmission line components are required for connecting various stages of RF source. To test these passive transmission line components at high power, a 3 MW test facility based on the concept of Traveling Wave Resonator (TWR) is underway. A high power CW RF amplifier is required to feed RF power to 10 dB coupler of TWR. To fulfill the requirement a tetrode based amplifier is designed to operate in class B with optimized efficiency, gain and harmonics level. The detail design is carried out to estimate operational parameters derived from the data sheet of selected tetrode, simulation for RF cavities, power supply requirements and thermal management for CW operation.