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Title: New Transverse Bunch-by-Bunch Feedback System at TLS

Abstract

An FPGA based transverse bunch-by-bunch feedback system was implemented and commissioned to replace the existing analog transverse feedback system in order to suppress more effectively multi-bunch instabilities caused by the resistive wall of the vacuum chamber, cavity-like structures and ions related instability. This system replaces existing analog transverse feedback system to enlarge the tunability of the working point. Lower chromaticity is possible with feedback system that is very helpful for injection efficiency improvement. Top-up and high current operation is benefit for this upgrade. One feedback loop suppresses horizontal and vertical multi-bunch instabilities simultaneously. The clean and simple structure makes the system simple and reliable. This study also presents the preliminary result of commissioning the new transverse feedback system.

Authors:
; ; ; ; ; ;  [1]; ;  [2]
  1. National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China)
  2. JASRI/SPring-8, Hyogo (Japan)
Publication Date:
OSTI Identifier:
21049310
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 879; Journal Issue: 1; Conference: 9. international conference on synchrotron radiation instrumentation, Daegu (Korea, Republic of), 28 May - 2 Jun 2006; Other Information: DOI: 10.1063/1.2436028; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM BUNCHING; BEAM CURRENTS; COMMISSIONING; CONTROL SYSTEMS; EFFICIENCY; INSTABILITY; LIGHT SOURCES; OPERATION; PARTICLE BEAMS; SYNCHROTRON RADIATION

Citation Formats

Hu, K. H., Kuo, C. H., Hsu, S. Y., Lee, Demi, Chen, Jenny, Wang, C. J., Hsu, K. T., Kobayashi, K., and Nakamura, T. New Transverse Bunch-by-Bunch Feedback System at TLS. United States: N. p., 2007. Web. doi:10.1063/1.2436028.
Hu, K. H., Kuo, C. H., Hsu, S. Y., Lee, Demi, Chen, Jenny, Wang, C. J., Hsu, K. T., Kobayashi, K., & Nakamura, T. New Transverse Bunch-by-Bunch Feedback System at TLS. United States. doi:10.1063/1.2436028.
Hu, K. H., Kuo, C. H., Hsu, S. Y., Lee, Demi, Chen, Jenny, Wang, C. J., Hsu, K. T., Kobayashi, K., and Nakamura, T. Fri . "New Transverse Bunch-by-Bunch Feedback System at TLS". United States. doi:10.1063/1.2436028.
@article{osti_21049310,
title = {New Transverse Bunch-by-Bunch Feedback System at TLS},
author = {Hu, K. H. and Kuo, C. H. and Hsu, S. Y. and Lee, Demi and Chen, Jenny and Wang, C. J. and Hsu, K. T. and Kobayashi, K. and Nakamura, T.},
abstractNote = {An FPGA based transverse bunch-by-bunch feedback system was implemented and commissioned to replace the existing analog transverse feedback system in order to suppress more effectively multi-bunch instabilities caused by the resistive wall of the vacuum chamber, cavity-like structures and ions related instability. This system replaces existing analog transverse feedback system to enlarge the tunability of the working point. Lower chromaticity is possible with feedback system that is very helpful for injection efficiency improvement. Top-up and high current operation is benefit for this upgrade. One feedback loop suppresses horizontal and vertical multi-bunch instabilities simultaneously. The clean and simple structure makes the system simple and reliable. This study also presents the preliminary result of commissioning the new transverse feedback system.},
doi = {10.1063/1.2436028},
journal = {AIP Conference Proceedings},
number = 1,
volume = 879,
place = {United States},
year = {Fri Jan 19 00:00:00 EST 2007},
month = {Fri Jan 19 00:00:00 EST 2007}
}
  • Multi-bunch instabilities deteriorate beam quality, increasing beam emittance, or even causing beam loss in the synchrotron light source. The feedback system is essential to suppress multi-bunch instabilities caused by the impedances of beam ducts, and trapped ions. A new FPGA based transverse and longitudinal bunch-by-bunch feedback system have been commissioned at the Taiwan Light Source recently, A single feedback loop is used to simultaneously suppress the horizontal and the vertical multi-bunch instabilities. Longitudinal instabilities caused by cavity-like structures are suppressed by the longitudinal feedback loop. The same FPGA processor is employed in the transverse feedback and the longitudinal feedback systemmore » respectively. Diagnostic memory is included in the system to capture the bunch oscillation signal, which supports various studies.« less
  • Multi-bunch instabilities degrade beam quality through increased beam emittance, energy spread and even beam loss. Feedback systems are used to suppress multi-bunch instabilities associated with the resistive wall of the beam ducts, cavity-like structures, and trapped ions. A new digital transverse bunch-by-bunch feedback system has recently been commissioned at the Taiwan Light Source, and has replaced the previous analog system. The new system has the advantages that it enlarges the tune acceptance and improves damping for transverse instability at high currents, such that top-up operation is achieved. After a coupled-bunch transverse instability was suppressed, more than 350 mA was successfullymore » stored during preliminary commissioning. In this new system, a single feedback loop simultaneously suppresses both horizontal and vertical multi-bunch instabilities. Investigating the characteristics of the feedback loop and further improving the system performances are the next short-term goals. The feedback system employs the latest generation of field-programmable gate array (FPGA) processor to process bunch signals. Memory has been installed to capture up to 250 msec of bunch oscillation signal, considering system diagnostics suitable to support various beam physics studies.« less
  • No abstract prepared.
  • The Pohang Light Source upgrade (PLS-II) project has successfully upgraded the Pohang Light Source (PLS). The main goals of the PLS-II project are to increase the beam energy to 3 GeV, increase the number of insertion devices by a factor of two (20 IDs), increase the beam current to 400 mA, and at the same time reduce the beam emittance to below 10 nm by using the existing PLS tunnel and injection system. Among 20 insertion devices, 10 narrow gap in-vacuum undulators are in operation now and two more in-vacuum undulators are to be installed later. Since these narrow gapmore » in-vacuum undulators are most likely to produce coupled bunch instability by the resistive wall impedance and limit the stored beam current, a bunch by bunch feedback system is implemented to suppress coupled bunch instability in the PLS-II. This paper describes the scheme and performance of the PLS-II bunch by bunch feedback system.« less
  • The ALS transverse coupled-bunch feedback system is described along with some recent commissioning results. Results presented include transfer function measurements, demonstrations of multi-bunch damping, and demonstrations of simultaneous transverse and longitudinal systems operation. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.