April 21-28, 2025—The research team led by Prof. Wei Yelong at the National Synchrotron Radiation Laboratory (NSRL) of the University of Science and Technology of China (USTC) has made significant progress in the high-power testing of China’s first domestically developed C-band spherical pulse compressor, achieving the highest power level recorded for such devices in the country.
In linear accelerators, the filling time of traveling-wave accelerating tubes is typically hundreds of nanoseconds (ns), while the microwave pulses generated by klystrons last several microseconds (μs). Only a fraction of these pulses (hundreds of ns) are used for electron acceleration, resulting in low microwave utilization efficiency. Pulse compressors, also known as energy multipliers, address this issue by compressing long μs-scale microwave pulses into shorter ns-scale pulses while achieving a several-fold power gain. This technology effectively resolves the limitations of klystron output power and pulse efficiency, significantly reducing the cost of microwave systems. Among various pulse compressor designs, spherical pulse compressors are widely adopted in large-scale linear accelerators globally due to their compact structure, low surface field, and operational stability.
The C-band spherical pulse compressor is a critical component of the injector pre-research project for the Zhejiang Industrial Light Source (under preparation in Jinhua). Through optimized structural design, the team successfully reduced surface field strength (particularly improving field distribution at the coupling port) and innovatively implemented a split-type water-cooling system for the coupling port and spherical cavity, minimizing the risk of electrical arcing.
During the first phase of high-power testing, the pulse compressor achieved an input power of 8.7 MW and an output peak power of 53.9 MW, marking a 6.2-fold peak power gain—the highest recorded for domestic C-band spherical pulse compressors and on par with international counterparts. The device demonstrated stable performance in vacuum, water-cooling, and other operational parameters throughout the tests, conducted at the Southern Light Source Testing Platform of the Institute of High Energy Physics (IHEP), Chinese Academy of Sciences (CAS), in Dongguan. These results provide crucial technical advancements for pulse compressor development worldwide. The second phase of high-power testing is currently underway as planned.
