Abstracts Brochure - CERN

THPCH — Poster Session 29-Jun-06 16:00 - 18:00
bunch train) and ultra fast (bunch by bunch) repetitive beam movements by adaptive feed forwards. In this paper,
we will introduce the IBFB design concept and report on first test measurements with newly designed stripline beam
position monitors for the VUV-FEL.
Commissioning of the Digital Transverse Bunch-by-bunch Feedback System for the TLS
Multi-bunch instabilities degrade the beam
quality leading to increased beam emittance,
energy spread or even to beam loss. The
feedback system is used to suppress multibunch
instabilities due to resistive wall of the
K.H. Hu, J. Chen, P.J. Chou, K.-T. Hsu, C.H. Kuo (NSRRC) A. Chao
(SLAC) K. Kobayashi, T. Nakamura (JASRI/SPring-8) W.-T. Weng
(BNL)
beam ducts, cavity-like structures and trapped ions. A new digital transverse bunch-by-bunch feedback system was
commissioned at the Taiwan Light Source recently, and has replaced the previous analog system. The new system has
the advantages that it enlarges the tune acceptance compared with the old system, enhances damping for transverse
instability at high current, and as a result, top-up operation was achieved. In this new system, a single feedback loop
simultaneously suppresses both the horizontal and vertical multi-bunch instabilities. The feedback system employs
the latest generation FPGA feedback processor to process bunch signals. Memory installed to capture up to 250 msec
bunch oscillation signal has included the considerations for system diagnostic and should be able to support various
beam physics study.
FPGA-based Longitudinal Bunch-by-bunch Feedback System for TLS
A FPGA Based Longitudinal Bunch-by-
Bunch Feedback System for TLS is commissioning
recently to suppress strong longitudinal
oscillation. The system consists of
C.H. Kuo, J. Chen, K.-T. Hsu, K.H. Hu, W.K. Lau, M.-S. Yeh (NSRRC)
M. Dehler (PSI) K. Kobayashi, T. Nakamura (JASRI/SPring-8)
pickup, Bunch oscillation detector, FPGA based feedback processor borrow form the design of Spring8. Modulator
converts the correction signal to the carrier frequency and longitudinal kicker which was re-designed form SLS’ and
working at 1374 MHz. The feedback processor is based upon latest generation FPGA feedback processor to process
bunch signals. The memory capture is up to 250 msec bunch oscillation signal. The software and hardware design
are also included for system diagnostic and support various beam physics study. Preliminary commission result will
be summaried in this report.
A Turn-by-turn, Bunch-by-bunch Diagnostics System for the PEP-II Transverse Feedback
Systems
A diagnostics system centered around commercial
fast 8-bit digitizer boards has been
implemented for the transverse feedback systems
at PEP-II. The boards can accumulate
R. Akre, W.S. Colocho, A. Krasnykh, V. Pacak, R. Steele, U. Wienands
(SLAC)
bunch-by-bunch position data for 4800 turns (35 ms) in the x plane and the y plane. A dedicated trigger chassis
allows to trigger the data acquisition on demand, or on an injection shot to diagnose injection problems, and provides
gating signals for grow-damp measurements. Usually, the boards constantly acquire data and a beam abort stops
data acquitision, thus preserving the last 4800 turns of position information before a beam abort. Software in a local
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