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Title: Computer modelling of bunch-by-bunch feedback for the SLAC B-factory design

Abstract

The SLAC B-factory design, with over 1600 high current bunches circulating in each ring, will require a feedback system to avoid coupled-bunch instabilities. A computer model of the storage ring, including the RF system, wave fields, synchrotron radiation loss, and the bunch-by-bunch feedback system is presented. The feedback system model represents the performance of a fast phase detector front end (including system noise and imperfections), a digital filter used to generate a correction voltage, and a power amplifier and beam kicker system. The combined ring-feedback system model is used to study the feedback system performance required to suppress instabilities and to quantify the dynamics of the system. Results are presented which show the time development of coupled bunch instabilities and the damping action of the feedback system. 3 refs., 5 figs., 2 tabs.

Authors:
; ; ; ; ; ;  [1];  [2]
  1. (Stanford Linear Accelerator Center, Menlo Park, CA (USA))
  2. (Lawrence Berkeley Lab., CA (USA))
Publication Date:
Research Org.:
Stanford Linear Accelerator Center, Menlo Park, CA (USA)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (USA)
OSTI Identifier:
5731116
Report Number(s):
SLAC-PUB-5466; LBL-30772; CONF-910505-105
ON: DE91012968
DOE Contract Number:
AC03-76SF00515
Resource Type:
Conference
Resource Relation:
Conference: 1991 Institute of Electrical and Electronics Engineers (IEEE) particle accelerator conference (PAC), San Francisco, CA (USA), 6-9 May 1991
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM BUNCHING; FEEDBACK; MESON FACTORIES; B MESONS; COMPUTERIZED SIMULATION; INSTABILITY; KICKER MAGNETS; RF SYSTEMS; STANFORD LINEAR ACCELERATOR CENTER; ACCELERATORS; BEAM DYNAMICS; BOSONS; ELECTRICAL EQUIPMENT; ELECTROMAGNETS; ELEMENTARY PARTICLES; EQUIPMENT; HADRONS; MAGNETS; MESONS; NATIONAL ORGANIZATIONS; PSEUDOSCALAR MESONS; SIMULATION; US DOE; US ERDA; US ORGANIZATIONS; 430200* - Particle Accelerators- Beam Dynamics, Field Calculations, & Ion Optics

Citation Formats

Briggs, D., Fox, J.D., Hosseini, W., Klaisner, L., Morton, P., Pellegrin, J.L., Thompson, K.A., and Lambertson, G. Computer modelling of bunch-by-bunch feedback for the SLAC B-factory design. United States: N. p., 1991. Web.
Briggs, D., Fox, J.D., Hosseini, W., Klaisner, L., Morton, P., Pellegrin, J.L., Thompson, K.A., & Lambertson, G. Computer modelling of bunch-by-bunch feedback for the SLAC B-factory design. United States.
Briggs, D., Fox, J.D., Hosseini, W., Klaisner, L., Morton, P., Pellegrin, J.L., Thompson, K.A., and Lambertson, G. Wed . "Computer modelling of bunch-by-bunch feedback for the SLAC B-factory design". United States. doi:. https://www.osti.gov/servlets/purl/5731116.
@article{osti_5731116,
title = {Computer modelling of bunch-by-bunch feedback for the SLAC B-factory design},
author = {Briggs, D. and Fox, J.D. and Hosseini, W. and Klaisner, L. and Morton, P. and Pellegrin, J.L. and Thompson, K.A. and Lambertson, G.},
abstractNote = {The SLAC B-factory design, with over 1600 high current bunches circulating in each ring, will require a feedback system to avoid coupled-bunch instabilities. A computer model of the storage ring, including the RF system, wave fields, synchrotron radiation loss, and the bunch-by-bunch feedback system is presented. The feedback system model represents the performance of a fast phase detector front end (including system noise and imperfections), a digital filter used to generate a correction voltage, and a power amplifier and beam kicker system. The combined ring-feedback system model is used to study the feedback system performance required to suppress instabilities and to quantify the dynamics of the system. Results are presented which show the time development of coupled bunch instabilities and the damping action of the feedback system. 3 refs., 5 figs., 2 tabs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed May 01 00:00:00 EDT 1991},
month = {Wed May 01 00:00:00 EDT 1991}
}

Conference:
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  • A bunch-by-bunch feedback scheme is studied for damping coupled bunch synchrotron oscillations in the proposed PEP II B Factory. The quasi-linear feedback systems design incorporates a phase detector to provide a quantized measure of bunch phase, digital signal processing to compute an error correction signal and a kicker system to correct the energy of the bunches. A farm of digital processors, operating in parallel, is proposed to compute correction signals for the 1658 bunches of the B Factory. This paper studies the use of down sampled processing to reduce the computational complexity of the feedback system. We present simulation resultsmore » showing the effect of down sampling on beam dynamics. Results show that down sampled processing can reduce the scale of the processing task by a factor of 10.« less
  • A bunch-by-bunch feedback scheme is studied for damping coupled bunch synchrotron oscillations in the proposed PEP II B Factory. The quasi-linear feedback systems design incorporates a phase detector to provide a quantized measure of bunch phase, digital signal processing to compute an error correction signal and a kicker system to correct the energy of the bunches. A farm of digital processors, operating in parallel, is proposed to compute correction signals for the 1658 bunches of the B Factory. This paper studies the use of down sampled processing to reduce the computational complexity of the feedback system. We present simulation resultsmore » showing the effect of down sampling on beam dynamics. Results show that down sampled processing can reduce the scale of the processing task by a factor of 10.« less
  • The Low Energy Ring (LER) of the PEP-II B-Factory will use wiggler magnet systems for emittance control and additional damping. The wiggler baseline is a set of 11 individual iron core, water cooled, dipole magnets designed operate at 1.6 T and generate 400 kW of synchrotron radiation. Space has been provided to add a second wiggler with additional 400 kW of synchrotron radiation if more damping is needed in the future. A copper vacuum chamber is used with continuous antechambers connected to both sides of the beam chamber via slots. Synchrotron radiation dump surfaces both antechambers. We describe the designmore » and analysis of the wiggler magnets and the salient features of the vacuum chamber and dumps.« less
  • The design of the lattice for the High Energy Ring (HER) of the SLAC B-Factory has several special features, notably provision for octupole compensation of amplitude dependent tune shift effects and a beta-beat scheme for semi-local chromaticity correction. In the arcs adjacent to the interaction point (IP) the beta functions are enhanced to allow the use of non-interlaced sextupoles to compensate the chromaticity of the interaction region. A closed bump of beta {open_quotes}mismatch{close_quotes} is generated by two vertically focusing quadrupoles spaced 2 betatron wavelengths apart. The beta-beat has two advantages: it enhances the ratio between the horizontal and vertical betamore » functions at the sextupoles and, because of the locally higher beta function, allows weaker sextupoles to be used. The standard design uses a 60 degree/cell lattice but a 90 degree/cell lattice may also be used if lower emittances and momentum compaction factor are desired.« less
  • This report compares and contrasts the approaches taken at KEK and SLAC in the design of trigger and data acquisition systems for the high-luminosity environment of a B Factory. The description of the SLAC design presented obtains from work in progress by a working group of an ongoing workshop. 3 refs., 10 figs.