Research on the newest GaN-Based solid-state power amplifier for CiADS project

Institute of Modern Physics (IMP), Chinese Academy of Sciences is the first domestic institute to widely apply solid-state power amplifier (SSPA) to linear accelerator project from China Accelerator Driven Sub-critical System (C-ADS) project started since 2011. Until now, SSPA design has already been considered for two large-scale scientific facilities in Guangdong Province of southeast China: China initiative Accelerator Driven System (CiADS) and High Intensity Heavy-ion Accelerator Facility (HIAF). The SSPA was developed rapidly due to the reliable technologies of LDMOS-based (laterally diffused metal oxide semiconductor) power amplifiers. With the maturation of GaN (Gallium Nitride) technology, GaN-based amplifiers have been studied in the field of accelerators since 2020. Last year, IMP made new progress with GaN SSPA, measuring power modules at three fundamental frequency points of 162.5 MHz, 325 MHz, and 650 MHz. The first 50 kW rack with GaN SSPA was measured at 650 MHz in IMP, and its modules offer huge advantages of 40% output power and 8% efficiency compared to the newest LDMOS at the same frequency, which holds a fascination for our project. Until the beginning of 2023, the prototype power modules on three frequency points were completed and tested. This paper will detail the design development of GaN technology and its technical characteristics.