改进铜铌溅射型QWR超导腔性能的探讨

通过直流偏压二级溅射方法，在无氧铜腔体表面溅射一层铌膜，研制了铜铌溅射型射频超导1/4波长谐振腔(quarter wave resonator,QWR)，该腔主要用于重离子的加速，是北京放射性核束装置中后加速部分的预研项目.目前国际上很多实验室都在研究进一步提高铜铌溅射型QWR超导腔的性能，通过多种方法的实验研究，发现在无氧铜衬底与铌膜之间加入一层氮 化铌（NbN）薄膜，可以使得表面铌膜的超导温度转变点由原来的8.8K提高到了接近9.6K ，该方法有可能成为提高QWR腔加速性能的重要途径，目前进一步研究正 关键词： 溅射 QWR超导腔 氮化铌NbN 超导温度

Studies on the improvement of niobium-sputtered quarter wave resonator supercond ucting cavity

Quarter wave resonator (QWR) is the best choice of the acceleration cavity for heavy ion superconducting accelerator. Using dc bias-voltage sputtering system, w e can sputter niobium films of several microns on the oxygen-free high-conductiv ity copper(OFHC) substrate. Good superconducting properties and acceleration pro perties of the cavity can be obtained. But compared with niobium cavity, it has very low Q and E_acc. Niobium nitride (NbN) is a good superconducto r, and it has a higher superconducting transition temperature (T_c) th an pu re niobium. Through experiments, we find that the T_c transition point of n iobium films rises to about 9.6K by using NbN interlayer between OFHC substrate and niobium films. So using this method can improve the superconducting properti es and thus the acceleration properties.