An on-site test of the 166.6 MHz Superconducting RF Cavity, a core component of the High Energy Photo Source-Test Facility (HEPS-TF), was conducted at the Institute of High Energy Physics (IHEP) on March 15. Experts from Tsinghua University, Peking University and IHEP were given a report by the project research group and witnessed the on-site test.

The 166.6 MHz superconducting RF cavity is the world's first low-frequency (<200 MHz), high current (> 200 mA), high power (> 150 kW), beta = 1 superconducting cavity. The test results at temperatures of 4.2 K and 2 K showed that the cavity’s performance has reached a world-leading level, and are an important milestone for the HEPS-TF project.

Vertical tests at 166.6 MHz and beta = 1, at temperatures of 4.2 K and 2 K, showed that the cavity has reached the design goals and has a high Q0 value. At 4.2 K, the cavity pressure is 1.5 MV and Q0 is 2.4x109 (compared to the design values of 1.5 MV and Q0> 5*108@4.2K), the surface resistance at low field is 10 nΩ, and the surface residual resistance is only 2.3 nΩ.

The cavity was designed by the high-frequency group from the Accelerator Division and manufactured by the Beijing High Energy Racing New Technology Co., Ltd.