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Title: Experimental evidence of ion-induced instabilities in the NSLS-II storage ring

Abstract

Fast ion instability has been identified as one of the most prominent instabilities in the recently constructed NSLS-II storage ring at Brookhaven National Laboratory. At a relatively low beam current (~ 25 mA) multi-bunch fills, ion-induced instabilities have already been observed during the early stages of machine commissioning. At present user operation with 250 mA in ~1000 bunches, the fast ion still remains the dominant instability, even after months of vacuum conditioning at high current. Ion-induced dipole motions of the electron beam have been suppressed using the transverse bunch-by-bunch (BxB) feedback system. However other adverse effects of this instability, such as the vertical beam size increase along the bunch train cannot be cured by the feedback system. Therefore, to achieve the NSLS-II design current of 500 mA while maintaining a small vertical beam emittance, it is important to further understand the fast ion instability and develop mitigation techniques. This paper reports on a series of ion-instability observations at various fill patterns and beam currents using start-of-art NSLS-II diagnostic tools.

Authors:
 [1];  [1];  [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1413910
Report Number(s):
BNL-114327-2017-JA
Journal ID: ISSN 0168-9002; TRN: US1800470
Grant/Contract Number:  
SC0012704
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment
Additional Journal Information:
Journal Volume: 861; Journal Issue: C; Journal ID: ISSN 0168-9002
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; Fast ion; Bunch by bunch feedback; Ion frequency; National Synchrotron Light Source II

Citation Formats

Cheng, Weixing, Li, Yongjun, and Podobedov, Boris. Experimental evidence of ion-induced instabilities in the NSLS-II storage ring. United States: N. p., 2017. Web. doi:10.1016/j.nima.2017.03.020.
Cheng, Weixing, Li, Yongjun, & Podobedov, Boris. Experimental evidence of ion-induced instabilities in the NSLS-II storage ring. United States. doi:10.1016/j.nima.2017.03.020.
Cheng, Weixing, Li, Yongjun, and Podobedov, Boris. Sun . "Experimental evidence of ion-induced instabilities in the NSLS-II storage ring". United States. doi:10.1016/j.nima.2017.03.020. https://www.osti.gov/servlets/purl/1413910.
@article{osti_1413910,
title = {Experimental evidence of ion-induced instabilities in the NSLS-II storage ring},
author = {Cheng, Weixing and Li, Yongjun and Podobedov, Boris},
abstractNote = {Fast ion instability has been identified as one of the most prominent instabilities in the recently constructed NSLS-II storage ring at Brookhaven National Laboratory. At a relatively low beam current (~ 25 mA) multi-bunch fills, ion-induced instabilities have already been observed during the early stages of machine commissioning. At present user operation with 250 mA in ~1000 bunches, the fast ion still remains the dominant instability, even after months of vacuum conditioning at high current. Ion-induced dipole motions of the electron beam have been suppressed using the transverse bunch-by-bunch (BxB) feedback system. However other adverse effects of this instability, such as the vertical beam size increase along the bunch train cannot be cured by the feedback system. Therefore, to achieve the NSLS-II design current of 500 mA while maintaining a small vertical beam emittance, it is important to further understand the fast ion instability and develop mitigation techniques. This paper reports on a series of ion-instability observations at various fill patterns and beam currents using start-of-art NSLS-II diagnostic tools.},
doi = {10.1016/j.nima.2017.03.020},
journal = {Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment},
number = C,
volume = 861,
place = {United States},
year = {Sun Mar 12 00:00:00 EST 2017},
month = {Sun Mar 12 00:00:00 EST 2017}
}

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