激活后的NEG薄膜在氖气保护下的应用研究

Vacuum Performance of Activated NEG Coatings under Neon Venting

NEG薄膜目前已成为新一代同步辐射光源储存环真空室表面处理的主要手段,HALF光源拟采用镀Ti-Zr-V NEG薄膜的方式以满足储存环真空度的设计要求。在一些情况下,需要打开真空室以更换某些故障件或安装插入件等,这将使NEG薄膜暴露大气,严重损伤薄膜的吸气性能及使用寿命,此外也需要数周时间使真空度恢复到原有水平。因此采取向真空室充入Ne气的方法能在一定程度上保护激活后的NEG薄膜,从而避免再次激活薄膜以延长使用寿命和节省时间,另外进行了充入N_(2)的对比实验。结果表明,充入Ne气后,真空度恢复后能满足静态真空度的要求,无需激活,从而延长NEG薄膜的使用寿命并且节省时间。而充入N_(2)后,真空度恢复后达不到静态真空度的要求。但通过低温激活,NEG薄膜均能恢复一定活性并达到静态真空度要求。相对于N_(2),在Ne气保护作用下真空度恢复的更好。通过对残余气体的分析,发现低温激活前后Ne的含量均极低,对束流的稳定性不会产生影响,进一步证明了充入Ne气的可行性。

Non-evaporable getter(NEG)coatings have become the main method of surface treatments for the vacuum chambers of new generation synchrotron radiation light source.Ti-Zr-V coatings are currently planned to be used in the vacuum chambers of Hefei Advanced Light Source Facility(HALF)storage ring to meet vacuum.Occasionally the vacuum chambers are inevitably exposed to the atmosphere to replace some damaged components or install insertion devices,which will damage the performance and life of NEG coatings,and take several weeks to restore the original vacuum.Therefore,a neon venting system is used,which could protect the vacuum performance of activated NEG coatings to a certain extent and avoid reactivating the coatings to prolong coatings’lifetime and save operation time.Meanwhile,a comparative experiment is carried out under N_(2)venting.After neon venting,the results show that the vacuum can meet the static vacuum degree without activating coatings to prolong the lifetime and save recovery time,but it cannot meet the static vacuum after N_(2)venting.After low-temperature activation of NEG coatings,the vacuum can meet the pressure in both cases but is better under neon gas.The percentage of neon is very low in both cases by analysis of residual gases,which does not affect the stability of the beam and further proves the feasibility of neon venting.