Development of a continuous-wave photocathode very-high-frequency electron gun for S3FEL
Abstract
A very-high-frequency (VHF) electron gun operating at a resonant frequency of 216.667 MHz has been developed at Tsinghua University for the Shenzhen Superconducting Soft X-ray Free-Electron Laser (S3FEL) facility. Building upon the SHINE gun design, the cavity profile was optimized to achieve a higher cathode electric-field gradient and a higher accelerating voltage at comparable input power. The revised cavity geometry also yields improved multipacting performance. In addition, thermal analysis was carried out to guide the water-cooling design, and enhanced cooling was implemented in the vicinity of the cathode. During high-power conditioning, 82 kW of continuous-wave radio-frequency power was successfully coupled into the gun, corresponding to a cathode gradient of 29.9 MV/m and an accelerating voltage of 856 kV. The gun voltage surpasses the previous world record for room-temperature VHF guns. The maximum dark current measured by the Faraday cup at the gun exit was only 6.8 nA.
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BibTeX
@misc{zheng2026development,
title = {{Development of a continuous-wave photocathode very-high-frequency electron gun for $\rm S^3FEL$}},
author = {Lianmin Zheng and Yitong Duan and Yuanyuan Qin and Baiting Song and Yang Yu and Zixuan Dong and Yijiang Zhu and Yanqing Jia and Jiaru Shi and Renkai Li and Wenhui Huang and Huaibi Chen and Chuanxiang Tang and Yingchao Du},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.07604},
eprint = {2610.07604},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.07604},
}
RIS
TY - UNPB
TI - Development of a continuous-wave photocathode very-high-frequency electron gun for S^3FEL
AU - Lianmin Zheng
AU - Yitong Duan
AU - Yuanyuan Qin
AU - Baiting Song
AU - Yang Yu
AU - Zixuan Dong
AU - Yijiang Zhu
AU - Yanqing Jia
AU - Jiaru Shi
AU - Renkai Li
AU - Wenhui Huang
AU - Huaibi Chen
AU - Chuanxiang Tang
AU - Yingchao Du
PY - 2026
DA - 2026/10/06
PB - arXiv
DO - 10.48550/arxiv.2610.07604
UR - https://arxiv.org/abs/2610.07604
AB - A very-high-frequency (VHF) electron gun operating at a resonant frequency of 216.667 MHz has been developed at Tsinghua University for the Shenzhen Superconducting Soft X-ray Free-Electron Laser (S^3FEL) facility. Building upon the SHINE gun design, the cavity profile was optimized to achieve a higher cathode electric-field gradient and a higher accelerating voltage at comparable input power. The revised cavity geometry also yields improved multipacting performance. In addition, thermal analysis was carried out to guide the water-cooling design, and enhanced cooling was implemented in the vicinity of the cathode. During high-power conditioning, 82 kW of continuous-wave radio-frequency power was successfully coupled into the gun, corresponding to a cathode gradient of 29.9 MV/m and an accelerating voltage of 856 kV. The gun voltage surpasses the previous world record for room-temperature VHF guns. The maximum dark current measured by the Faraday cup at the gun exit was only 6.8 nA.
ER -