IPAC2019 - List of Authors (Tian, Y.)

Paper	Title	Page
WEPGW102	Investigation on Mysterious Long-Term Orbit Drift at NSLS-II	2728
	Y. Hidaka, W.X. Cheng, L. Doom, R.P. Fliller, G. Ganetis, J. Gosman, C. Hetzel, R.A. Hubbard, D. Padrazo Jr, B. Podobedov, J. Rose, T.V. Shaftan, S.K. Sharma, V.V. Smaluk, T. Tanabe, Y. Tian, G.M. Wang, C.H. Yu BNL, Upton, Long Island, New York, USA
	Funding: The study is supported by U.S. DOE under Contract No. DE-SC0012704. Over a few months in 2018, we observed occasional episodes of relatively quick accumulation of correction strengths for the fast correctors (used by the fast orbit feedback) near Cell 4 (C04) region at NSLS-II Storage Ring. We immediately started investigating the problem, but the cause remained unclear. However, after coming back from the Fall shutdown, we experienced even faster drifts, at a rate of as much as 10 urad per day in terms of orbit kick angle accumulation. The risk of damage on the ring vacuum chambers by the continuing orbit drift without explanation eventually forced us to take emergency study shifts and temporarily lock out the C04 IVU beamline. After extensive investigation by many subsystem experts in Accelerator Division, ruling out many suspicious sources one by one, we were finally able to conclude the cause to be the localized ground motion induced by large temperature jumps of the utility tunnel right underneath the C04 straight section. We report the details of this incident.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW102
About •	paper received ※ 19 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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THPRB104	Improvements in Long-Term Orbit Stability at NSLS-II	4070
	Y. Hidaka, A. Caracappa, Y. Hu, B. Podobedov, R.M. Smith, Y. Tian, G.M. Wang BNL, Upton, Long Island, New York, USA
	Funding: The study is supported by U.S. DOE under Contract No. DE-SC0012704. We report our latest efforts to further improve long-term orbit stability at NSLS-II, on top of what is already provided by fast orbit feedback (FOFB) system. A DC local bump generation program, only utilizing RF beam position monitors (BPM) and compatible with FOFB, was first implemented and deployed in operation successfully, allowing on-demand fine adjustments of beamline source positions and angles. Then we introduced a simple feedback version that performs these bump corrections automatically as needed to maintain the sources within in 1 um/urad for select beamlines. In addition, an RF frequency feedback was also implemented to improve stability for 3-pole wigglers and bending magnet users. As a parallel effort, X-ray BPMs were included in a local feedback system to stabilize photon beam motion for several ID beamlines. However, this feedback scheme is not transparent to FOFB, and suspected to be the source of occasional saturation of fast corrector strength. As an alternative solution, the local bump program and its feedback version has been recently upgraded to include bumps with X-ray BPMs and in operation since April 2019.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB104
About •	paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Investigation on Mysterious Long-Term Orbit Drift at NSLS-II

2728

Y. Hidaka, W.X. Cheng, L. Doom, R.P. Fliller, G. Ganetis, J. Gosman, C. Hetzel, R.A. Hubbard, D. Padrazo Jr, B. Podobedov, J. Rose, T.V. Shaftan, S.K. Sharma, V.V. Smaluk, T. Tanabe, Y. Tian, G.M. Wang, C.H. Yu
BNL, Upton, Long Island, New York, USA

Funding: The study is supported by U.S. DOE under Contract No. DE-SC0012704.
Over a few months in 2018, we observed occasional episodes of relatively quick accumulation of correction strengths for the fast correctors (used by the fast orbit feedback) near Cell 4 (C04) region at NSLS-II Storage Ring. We immediately started investigating the problem, but the cause remained unclear. However, after coming back from the Fall shutdown, we experienced even faster drifts, at a rate of as much as 10 urad per day in terms of orbit kick angle accumulation. The risk of damage on the ring vacuum chambers by the continuing orbit drift without explanation eventually forced us to take emergency study shifts and temporarily lock out the C04 IVU beamline. After extensive investigation by many subsystem experts in Accelerator Division, ruling out many suspicious sources one by one, we were finally able to conclude the cause to be the localized ground motion induced by large temperature jumps of the utility tunnel right underneath the C04 straight section. We report the details of this incident.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW102

About •

paper received ※ 19 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPRB104

Improvements in Long-Term Orbit Stability at NSLS-II

4070

Y. Hidaka, A. Caracappa, Y. Hu, B. Podobedov, R.M. Smith, Y. Tian, G.M. Wang
BNL, Upton, Long Island, New York, USA

Funding: The study is supported by U.S. DOE under Contract No. DE-SC0012704.
We report our latest efforts to further improve long-term orbit stability at NSLS-II, on top of what is already provided by fast orbit feedback (FOFB) system. A DC local bump generation program, only utilizing RF beam position monitors (BPM) and compatible with FOFB, was first implemented and deployed in operation successfully, allowing on-demand fine adjustments of beamline source positions and angles. Then we introduced a simple feedback version that performs these bump corrections automatically as needed to maintain the sources within in 1 um/urad for select beamlines. In addition, an RF frequency feedback was also implemented to improve stability for 3-pole wigglers and bending magnet users. As a parallel effort, X-ray BPMs were included in a local feedback system to stabilize photon beam motion for several ID beamlines. However, this feedback scheme is not transparent to FOFB, and suspected to be the source of occasional saturation of fast corrector strength. As an alternative solution, the local bump program and its feedback version has been recently upgraded to include bumps with X-ray BPMs and in operation since April 2019.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB104

About •

paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)