基于双腔探头的流强精确测量
|
摘要
上海同步辐射光源(Shanghai Synchrotron Radiation Facility,SSRF,简称上海光源)作为中国第三代同步辐射装置,在为用户提供研究平台的同时,也在不断优化top-up运行模式,包括研究多束团注入以及注入效率优化等。而注入效率的优化需要精确测定注入束团的电荷量。由于ICT(Integrating Current Transformer)信号易受噪声干扰,分辨率不足1%,尤其在低电荷量注入时,分辨率将进一步降低,因此本文提出利用腔式探头分辨率高的特性,使用双腔探头检测注入流强的方案,并着重研究探头信号的采集处理方法。在上海光源高能输运线上完成的初步束流实验结果表明:注入流强的相对测量精度最好可以达到0.03%,满足储存环注入效率精确测量的要求。
[Background] The Shanghai synchrotron radiation facility(SSRF) is a third generation light source. It has been in operation for user experiment in decay mode since 2009. Meanwhile, the top-up operation is also under exploration in order to provide users with stable beam. A key technique for top-up mode is optimizing the injection efficiency by precisely controlling the injecting bunch charge. Therefore, it is essential to measure precisely the bunch charge at the high-energy transport line. The direct-current current transformers(DCCT) can measure the average beam current but can't measure the single bunch charge. Although the integrating current transformer(ICT)can measure the individual bunch charge, it is sensitive to different background noise with a resolution of less than1% and even worse under low bunch charge case. [Purpose] This study aims to improve the measuring resolution for the injected individual bunch charge by using cavity charge monitor. [Methods] Since the cavity monitor has high sensitivity and high resolution, it will be used to extract the bunch charge information. Normally, the cavity monitor works at C-band frequency and the generated radio frequency signal(RF) has to be down-converted to intermediate frequency(IF) signal. Thus a dual-cavity monitor working at different frequencies was developed to realize the two RF signals self-mixing. Moreover, because of the limited signal sampling rate, the four channel signal splicing scheme with strict synchronous phase-locked sampling technique was addopted to further improve the sampling rate.[Results] The experimental results show that IF signal amplitude is linear to the bunch charge quantity. Moreover, the test results presents the measuring sensitivity is better than 0.03%. [Conclusion] The novel dual cavity bunch charge system works well and meets the requirement of injection bunch charge measurement.
[Background] The Shanghai synchrotron radiation facility(SSRF) is a third generation light source. It has been in operation for user experiment in decay mode since 2009. Meanwhile, the top-up operation is also under exploration in order to provide users with stable beam. A key technique for top-up mode is optimizing the injection efficiency by precisely controlling the injecting bunch charge. Therefore, it is essential to measure precisely the bunch charge at the high-energy transport line. The direct-current current transformers(DCCT) can measure the average beam current but can't measure the single bunch charge. Although the integrating current transformer(ICT)can measure the individual bunch charge, it is sensitive to different background noise with a resolution of less than1% and even worse under low bunch charge case. [Purpose] This study aims to improve the measuring resolution for the injected individual bunch charge by using cavity charge monitor. [Methods] Since the cavity monitor has high sensitivity and high resolution, it will be used to extract the bunch charge information. Normally, the cavity monitor works at C-band frequency and the generated radio frequency signal(RF) has to be down-converted to intermediate frequency(IF) signal. Thus a dual-cavity monitor working at different frequencies was developed to realize the two RF signals self-mixing. Moreover, because of the limited signal sampling rate, the four channel signal splicing scheme with strict synchronous phase-locked sampling technique was addopted to further improve the sampling rate.[Results] The experimental results show that IF signal amplitude is linear to the bunch charge quantity. Moreover, the test results presents the measuring sensitivity is better than 0.03%. [Conclusion] The novel dual cavity bunch charge system works well and meets the requirement of injection bunch charge measurement.
引文
1 Zhao Z T.Commissioning of new synchrotron radiation facilities[J].IEEE Particle Accelerator Conference(PAC),2007,MOYKI02:17-21.DOI:10.1109/PAC.2007.4440321.
2 He J H,Zhao Z T.Shanghai synchrotron radiation facility[J].National Science Review,2014,1(2):171-172.DOI:10.1093/nsr/nwt039.
3 Jiang M H,Yang X,Xu H J,et al.Shanghai synchrotron radiation facility[J].Chinese Science Bulletin,2009,54(22):4171-4181.DOI:10.1007/s11434-009-0689-y.
4 Zhao Z T,Jiang B C,Leng Y B,et al.Performance optimization and upgrade of the SSRF storage ring[C].International Particle Accelerator Conference(IPAC2013),2013,MOPEA045:178-180.
5 Zhao Z T,Yin Y L,Li H H,et al.Progress towards top-up operation at SSRF[C].International Particle Accelerator Conference(IPAC2011),2011,THPC052:3008-3010.
6 Jiang B C,Lin G Q,Wang B L,et al.Multi-bunch injection for SSRF storage ring[J].Nuclear Science and Techniques,2015,26(5):050101.DOI:10.13538/j.1001-8042/nst.26.050101.
7 Webber R C.Tutorial on beam current monitoring[J].Proceedings of AIP Conference,2000,546(83):83-104.DOI:10.1063/1.1342580.
8 Covoa M K.Nondestructive synchronous beam current monitor[J].Review of Scientific Instruments,2014,85(12):125106.DOI:10.1063/1.4902903.
9 Chen J,Leng Y B,Zhang N,et al.The removal of interference noise of ICT using PCA method[C].International beam instrument conference(IBIC2018),2018,MOOC03:22-25.DOI:10.18429/JACoW-IBIC2018-MOOC03.
10 Lorenz R.Cavity beam position monitors[J].AIPConference Proceedings,1998,451(1):53-73.DOI:10.1063/1.57039.
11 Chen J,Leng Y B,Yu L Y,et al.Beam test results of high Q CBPM prototype for SXFEL[J].Nuclear Science and Techniques,2017,28(4):51.DOI:10.1007/s41365-017-0195-x.
12 Yuan R X,Zhou W M,Chen Z C,et al.Design and teat of SXFEL cavity BPM[J].Chinese Physics C,2013,37(11):118001.DOI:10.1088/1674-1137/37/11/118001.
13 Lai L W,Leng Y B,Yi X,et al.DBPM signal processing with field programmable gate arrays[J].Nuclear Science and Techniques,2011,22:129-133.
2 He J H,Zhao Z T.Shanghai synchrotron radiation facility[J].National Science Review,2014,1(2):171-172.DOI:10.1093/nsr/nwt039.
3 Jiang M H,Yang X,Xu H J,et al.Shanghai synchrotron radiation facility[J].Chinese Science Bulletin,2009,54(22):4171-4181.DOI:10.1007/s11434-009-0689-y.
4 Zhao Z T,Jiang B C,Leng Y B,et al.Performance optimization and upgrade of the SSRF storage ring[C].International Particle Accelerator Conference(IPAC2013),2013,MOPEA045:178-180.
5 Zhao Z T,Yin Y L,Li H H,et al.Progress towards top-up operation at SSRF[C].International Particle Accelerator Conference(IPAC2011),2011,THPC052:3008-3010.
6 Jiang B C,Lin G Q,Wang B L,et al.Multi-bunch injection for SSRF storage ring[J].Nuclear Science and Techniques,2015,26(5):050101.DOI:10.13538/j.1001-8042/nst.26.050101.
7 Webber R C.Tutorial on beam current monitoring[J].Proceedings of AIP Conference,2000,546(83):83-104.DOI:10.1063/1.1342580.
8 Covoa M K.Nondestructive synchronous beam current monitor[J].Review of Scientific Instruments,2014,85(12):125106.DOI:10.1063/1.4902903.
9 Chen J,Leng Y B,Zhang N,et al.The removal of interference noise of ICT using PCA method[C].International beam instrument conference(IBIC2018),2018,MOOC03:22-25.DOI:10.18429/JACoW-IBIC2018-MOOC03.
10 Lorenz R.Cavity beam position monitors[J].AIPConference Proceedings,1998,451(1):53-73.DOI:10.1063/1.57039.
11 Chen J,Leng Y B,Yu L Y,et al.Beam test results of high Q CBPM prototype for SXFEL[J].Nuclear Science and Techniques,2017,28(4):51.DOI:10.1007/s41365-017-0195-x.
12 Yuan R X,Zhou W M,Chen Z C,et al.Design and teat of SXFEL cavity BPM[J].Chinese Physics C,2013,37(11):118001.DOI:10.1088/1674-1137/37/11/118001.
13 Lai L W,Leng Y B,Yi X,et al.DBPM signal processing with field programmable gate arrays[J].Nuclear Science and Techniques,2011,22:129-133.