射频超导腔的研究新进展

 射频超导谐振腔已经大规模地应用到粒子加速器领域，其优越之处在于它可以在CW模式或长宏脉冲模式下，提供高的加速梯度。射频超导已经成为自由电子激光和能量回收直线加速器的关键技术。经过30多年的研究发展，解决了超导腔的热崩溃、场致发射等诸多关键问题，目前加速梯度已经超过40 MV/m。高加速梯度的获得是射频超导领域的前沿热点，电抛光＋低温热处理技术使射频超导腔的加速梯度提高3～4 MV/m。最新发展起来的超导腔的干式处理可以改善超导腔的表面状况，提高超导腔的Q值，抑制次级电子发射效应，有可能成为提高超导腔性能的又一有效手段。

Recent progresses on RF superconductivity

RF superconducting cavities can work at CW mode or long pulse mode with high accelerating gradient. RF superconducting technology is widely used in particle accelerators. A lot of front scientific facilities are set up based on RF superconducting accelerators from low beta to high beta. RF superconductivity has become a most important technology in FEL and ERL. In the recent 30 years, the technology has made rapid progresses. The accelerating gradient can be over 40 MV/m by special treatments. High accelerating gradient is the front research in the field of RF superconductivity. EP + bake can provide an important method to increase the accelerating gradient. The accelerating gradient can increase by 3~4 MV/m after EP + bake treatment and the Q-drop is also improved. Recent developed dry treatment technique on superconducting cavities can improve the Q value of superconducting cavities and decrease the multipacting effect. The dry treatment might become another effective method to improve the performance of superconducting cavities.