On July 24, a research team led by Academician YANG Xueming and Prof. ZHANG Weiqing from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), achieved stable operation of an electron beam at a repetition rate of 1 Megahertz (1 MHz) for the first time. This result marks a meaningful step forward for the Dalian Advanced Light Source (DALS) project.
To support the development of DALS—a next-generation extreme ultraviolet free-electron laser (EUV FEL)—the Dalian municipal government launched a prototype initiative focused on building a superconducting continuous-wave (CW) electron injector. Launched in 2020, the project involves DICP and the Institute of Advanced Light Source Facilities in Shenzhen. Its main objective is to overcome the core technical challenges associated with generating high-repetition-rate, high-quality electron beams, and a prerequisite for future high-average-power FEL facilities.
Over the past five years, the team has advanced a series of key technologies, including a photocathode electron gun, ultrafast laser systems, solid-state radio-frequency (RF) power sources, superconducting accelerator modules, and cryogenic helium refrigeration systems. Earlier this year, the installation and individual system commissioning were completed. Following two weeks of integrated testing, the team began beam experiments at the megahertz scale and, at 11:15 p.m. on July 24, achieved stable beam operation.
The current test platform now supports acceleration of an electron beam with an average current of 0.1 milliamperes. Key performance indicators include beam energy exceeding 100 mega-electron-volts, a single-pulse charge above 100 picocoulombs, and a repetition rate of 1 MHz. The system has demonstrated stable operation for more than one hour, with beam energy stability maintained below 0.01% root-mean-square.
Achieving high-repetition-rate, high-quality electron beams is one of the most formidable technical challenges in building DALS. The success of this experiment demonstrates that the joint team has now gained critical expertise in the core enabling technologies, laying a strong foundation for future construction of DALS.