国际直线对撞机（ILC）高梯度射频超导加速腔研制

射频超导（sRF）加速技术已广泛应用于基于加速器的大科学装置．在国际直线对撞机和其他相关项目的推动下，近年来国际上多个射频超导实验室开展了高梯度射频超导加速腔的研制．在不断改进精密加工、电磁场调平、表面处理和电子束焊接等工艺流程的基础上，北京大学近期研制成功一只高质量9-cell超导加速腔，其加速梯度为32．6MV／m，品质因数大于1．0×10^10，性能指标全面达到国际直线对撞机（ILC）的要求．这表明我国已经掌握了高水平超导加速腔的研制技术，为未来参加ILC国际合作以及建设其他采用射频超导加速技术的大科学装置打下了良好基础．

The first high gradient 9-ceU superconducting cavity reached ILC requirements in China

Superconducting RF technology has been widely used for many large scientific facilities. Driven by International Linear Collider （ILC） project and other projects, efforts have been made for R＆D of high gradient superconducting cavities in SRF laboratories worldwide. Recently, a 1.3 GHz 9-cell TESLA type SRF cavity has been made at Peking University with careful control of machining, better field flatness tuning and improved surface treatment and electron beam welding （EBW）. The maximum of gradient is 32.4 MV/m and the intrinsic quality factor （Q0） is higher than 1.0 ×10^10. It is the first cavity which has reached the requirement for ILC both in accelerating gradient and intrinsic quality factor in China. The establishment of SRF technology for fabricating high quality cavities in China is beneficial for participation of both future international cooperation of ILC and other large scientific facilities using SRF accelerators.