NSRRC Activity Report 2022

100 NSRRC ACTIVITY REPORT 2022 released from the getter materials could considerably increase the vacuum pressure during activation. The ZAO NEG alloy mitigated outgassing during thermal activation, which led to a small rise in pressure (< 2 × 10 −5 mbar). After pumping for 10 days, the pressures reached 5.5 × 10 −10 mbar for EPU66 and 1.3 × 10 −9 mbar for EPU168. Because these two EPU chambers were new, and did not receive beam cleaning and bakeout after installation in the TPS tunnel, a beam-scrubbing treatment with synchrotron radiation was applied to improve their dynamic pressures. The dynamic pressures of the EPU66 and EPU168 chambers reached 6.3 × 10 −13 and 2.3 × 10 −12 mbar mA −1 , respectively, after the application of an accumulated beam dose of 100 Ah, as shown in Fig. 6 . The beam-cleaning data revealed no obvious discrepancies between the baked and unbaked vacuum systems. 3 Therefore, synchrotron radiation alone is sufficient for conditioning NEG cartridge-type vacuum systems; baking is not necessary. (Reported by Che-Kai Chan) References 1. C. C. Chang, C. K. Chan, L. H. Wu, C. Shueh, I. C. Shen, C. M. Cheng, I. C. Yang, Nucl. Instrum. Methods Phys. Res. A 853 , 36 (2017). 2. C. K. Chan, C. C. Chang, I. C. Yang, C. M. Cheng, B. Y. Chen, C. Shueh, Y. T. Cheng, Y. H. Gao, VACUUM 195 , 110693 (2022). 3. C. K. Chan, C. C. Chang, C. Shueh, I. C. Yang, L. H. Wu, B. Y. Chen, C. M. Cheng, Y. T. Huang, J. Y. Chuang, Y. T. Cheng, Y. M. Hsiao, Albert Sheng, Nucl. Instrum. Methods Phys. Res. A 851 , 57 (2017). Fig. 5 : Pumping curves of the NEG strip-type vacuum systems for (a) EPU66 and (b) EPU168 after NEG activation without baking. [Reproduced from Ref. 2] Fig. 6 : Dynamic pressures of the NEG strip-type vacuum systems for EPU66 and EPU168 as a function of accumulated beam dose. [Reproduced from Ref. 2]