2018 年 15 巻 2 号 p. 40-51
The nitrogen infusion, the recently discovered surface processing method for high-gradient and high-quality factor superconducting cavities, attracts much attention in the particle accelerator community in particular in the context of the International Linear Collider project. In this paper, we briefly review the basics of superconducting cavity, the causes of performance limitation, and the three modern surface processing methods including the nitrogen infusion and resultant cavity performances. The present understanding on physics behind these surface treatments are also discussed.