Author: Hidaka, Y.
Paper Title Page
MOPGW110 Study of the Beam Current Effects on the NSLS-II Storage Ring Optics Using Turn-by-Turn Data 375
 
  • J. Choi, Y. Hidaka
    BNL, Upton, Long Island, New York, USA
 
  These days, the techniques using the turn-by-turn data are well developed in analyzing the accelerator optics. We compared the data for the low and high beam currents and studied the beam current effects on the storage ring lattice optics. Also, by comparing the local transfer matrices, we analyzed the amounts of the impacts on the linear optics around the ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW110  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPGW101 A New Orbit Feedforward Table Generation Method for Insertion Devices 2724
 
  • Y. Hidaka, B.N. Kosciuk, B. Podobedov, J. Rank, T. Tanabe
    BNL, Upton, Long Island, New York, USA
 
  Funding: The study is supported by U.S. DOE under Contract No. DE-SC0012704.
A new method of orbit feedforward (FF) table generation for insertion devices (IDs) is proposed. The main purpose of the orbit FF table is to suppress orbit disturbance around a storage ring, caused by the gap/phase motion of an ID. A conventional procedure is to measure a closed orbit at a reference ID gap/phase state, and another one at a different state, with all types of orbit feedback (FB) systems disabled. Based on the difference orbit, the correction currents for the local ID correctors are estimated to cancel the global orbit distortion. The new method instead utilizes the orbit deviation at the beam position monitors within an ID straight section (ID BPMs) with respect to a dynamically changing orbit that is defined by the orbit at two BPMs bounding the ID straight. Correction currents are determined such that this orbit deviation at the ID BPMs is minimized. Being impervious to transverse kicks external to this bounded region, this measurement can be performed with a global orbit FB system turned on, which could allow parallel table generation for multiple IDs.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW101  
About • paper received ※ 17 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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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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THPMP053 Tuning Quadrupoles for Brighter and Sharper Ultra-fast Electron Diffraction Imaging 3571
 
  • X. Yang, L. Doom, M.G. Fedurin, Y. Hidaka, J.J. Li, D. Padrazo Jr, T.V. Shaftan, V.V. Smaluk, G.M. Wang, L.-H. Yu, Y. Zhu
    BNL, Upton, Long Island, New York, USA
  • W. Wan
    ShanghaiTech University, Shanghai, People’s Republic of China
 
  Funding: BNL LDRD
We report our proof-of-principle design and experi-mental commissioning of broadly tunable and low-cost transverse focusing lens system for MeV-energy electron beams at the ultra-fast electron diffraction (UED) beam-line of the Accelerator Test Facility II of BNL. We exper-imentally demonstrate the independent control over the size and divergence of the electron beam at the sample via tunable quadrupoles. By applying online optimiza-tion, we achieve minimum beam sizes 75 µm from 1 to 13 pC, two orders of magnitude higher charge density than previously achieved using conventional solenoid tech-nique. Finally, we experimentally demonstrate Bragg-diffraction image (BDI) with significant improvement up to 3 times brighter and 2 times sharper BDI peaks via the optimized quadrupoles, improvement larger with higher charge. The result could be crucial for the future single-shot ultra-fast electron microscope development.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP053  
About • paper received ※ 14 May 2019       paper accepted ※ 21 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  
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