Development of an 83.2 MHz, Three-Stage RF Amplifier for the SKKUCY-9 Cyclotron

In this paper, we describe the whole process of designing and manufacturing an 83.2 MHz, three-stage radio frequency (RF) amplifier for a SKKUCY-9 cyclotron. It consisted of a preamplifier, intermediate power amplifier (IPA), and power amplifier (PA) stage. The maximum power value for each stage is 0.05 kW, 1.5 kW, then 20 kW RF power. Formula calculation, circuit design, and electromagnetic analysis were implemented in the RF amplifier design. Along with the power stage and anode power supply, an RF amplifier control system for the RF amplifier was developed. After design and manufacturing, we conducted impedance matching measurements with a network analyzer to achieve 50Ω for the IPA and PA. Finally, we analyzed the RF amplifier characteristics by implementing RF testing with both a dummy load and a RF coupler. The expected and measured RF characteristics were in agreement, and a detailed analysis is described.