Modular 20 kW, 83.2-MHz Solid-State RF Amplifier for a 10-MeV Cyclotron

We describe the design and development of the modular 83.2-MHz, 20-kW solid-state-based radio frequency (RF) power amplifier, which will be used in a 10-MeV cyclotron (SKKUCY-10) under development. To obtain 20-kW RF power, we used 16 RF pallet amplifiers, 8 two-way power combiners (Wilkinson combiners), 2 four-way power combiners (Radial combiners), and a two-way power combiner (3-dB hybrid combiner). Through calculation, simulation, and measurement, we confirmed that the designed and measured parameter values of all the RF amplifier components were within 1%. In a dummy load test, RF power of more than 20 kW was achieved at 83.2 MHz, and efficiency was ~68%. A simple design structure and high efficiency are the main features of this RF amplifier.