| Paper |
Title |
Other Keywords |
Page |
| IT05 |
The Comparison of signal Processing Systems for Beam Position Monitors
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insertion, collider, single-bunch, electron |
12 |
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- G. Vismara
CERN, Geneva, Switzerland
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At first sight the problem of determining the beam
position from the ratio of the induced charges of the
opposite electrodes of a beam monitor seems trivial, but
up to now no unique solution has been found that fits the
various demands of all particle accelerators.
The purpose of this paper is to help instrumentalist in
choosing the best processing system for their particular
application.
The paper will present the different families in which
the processing systems can be grouped.
A general description of the operating principles with
relative advantages and disadvantages for the most
employed processing systems is also presented.
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| IT12 |
Use of Superimposed Alternating Currents in Quadrupoles to Measure Beam Position with Respect to their Magnetic Centre
|
quadrupole, electron, lattice, radiation |
38 |
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- N. Marks
CLRC, Daresbury Laboratory, Warrington, UK
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The positional stability of the electron beam in a modern
state-of-the-art synchrotron radiation source is critical, as
the many experimental users require consistency in the
position and dimensions of the incoming photon beams
which are incident on their experimental samples. At the
Daresbury Synchrotron Radiation Source (SRS),
inaccuracies in the measurements of the positions of both
beam position monitors and the lattice quadrupoles can be
overcome by measuring the position of the electron beam
with respect to the magnetic centres of the quadrupoles.
This was achieved by superimposing an alternating
('ripple') current on the direct current excitation of a
single lattice quadrupole and examining the resulting
beam oscillations at remote positions in the storage ring.
If the electron beam is then subjected to a local distortion
at the position of this quadrupole, the amplitude of the
beam oscillation induced by the superimposed current is
minimised (nominally zero) when the beam is at the
quadrupole's magnetic centre. This paper presents details
of the electrical circuit developed to inject an alternating
current into the coils of individual quadrupoles and gives
details of the results achieved to date.
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| CT07 |
The ELETTRA Streak Camera: System Set-Up and First Results
|
synchrotron, electron, single-bunch, cathode |
72 |
| |
- M. Ferianis
ELETTRA, Sincrotrone Trieste, Trieste, Italy
| |
At ELETTRA, a Streak Camera system has been
installed and tested. The bunch length is a significant
machine parameter to measure, as it allows a direct
derivation of fundamental machine characteristics, like its
broadband impedance. At ELETTRA the Light from a
Storage Ring Dipole is delivered through an optical
system to an Optical Laboratory where it can be observed
and analysed.
The Streak Camera is equipped with different timebases,
allowing both single sweep and dual sweep
operation modes, including the Synchroscan mode. The
Synchroscan frequency equal to 250 MHz, which is half
of the ELETTRA RF frequency, allows the acquisition of
consecutive bunches, 2ns apart. To fully exploit the
performances of the Streak Camera, an optical path has
been arranged which includes a fast opto-electronic
shutter. By doing so, the optical power deposited on the
photo-cathode is reduced in the different ELETTRA
fillings.
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| PS19 |
Photon counting detectors for fill structure measurements at visible wavelengths
|
photon, single-bunch, diagnostics, electron |
144 |
| |
- H.L. Owen
CLRC, Daresbury Laboratory, Warrington, UK
| |
When making accurate measurements of the relative
populations of electron bunches in a storage ring, notably
in light sources operating with only a single bunch filled,
the method of time-correlated single photon counting
gives the greatest dynamic range. The timing resolution
and background noise level of the photon detector
employed is critically important in determining the overall
performance of the system; hitherto the best performance
has been obtained detecting X-ray photons using
avalanche photodiodes. On the SRS at Daresbury a visible
light diagnostic station offers greater ease of access to
instrumentation and operational advantages. A review is
given of the detector types which have been employed,
and the performances which can be obtained using visible
light.
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| PT03 |
Measuring beam intensity and lifetime in BESSY II
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synchrotron, vacuum, injection, microtron |
159 |
| |
- R. Bakker, R. Georgen, P. Kuske, J. Kuszynski
BESSY, Berliner Speicherring-Gesellschaft für Synchrotronstrahlung mbH, Berlin, Germany
| |
The measurement of the intensity of the beam in the
transfer lines and the storage ring are based on current
transformers. The pulsed current in the transfer lines is
measured with passive Integrating Beam Current
Transformers (ICT). The bunch charge is transferred to a
DC-voltage and sampled with a multifunction I/O-board
of a PC. The beam current of the storage ring is measured
with a high precision Parametric Current Transformer
(PCT) and sampled by a high quality digital volt meter
(DVM). A stand alone PC is used for synchronisation,
real-time data acquisition and signal processing.
Current and lifetime data are updated every second and
send via CAN- bus to the BESSY II control system. All
PC programs are written in LabVIEW.
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| PT06 |
New digital BPM system for the Swiss light source
|
feedback, closed-orbit, booster, alignment |
168 |
| |
- M. Dehler, A. Jaggi, P. Pollet, T. Schilcher, V. Schlott, R. Uršič, R. deMonte
PSI, Paul Scherrer Institut, Villigen, Switzerland
| |
This paper presents a new digital beam position monitor
(DBPM) system which is currently under development
for the Swiss Light Source (SLS). It is designed to
provide sub-micron position data in normal closed orbit,
and feedback mode as well as turn by turn information
for machine studies and real time tune measurements.
The self calibrating four channel system consists of a RF
front end, a digital receiver and a DSP module. The same
electronics will be used in all sections of the SLS accelerator
complex. The system can be reconfigured in real
time to perform different kind of measurements like:
pulsed for linac and transfer lines, first turn, turn-by-turn,
closed orbit, feedback and even tune mode for booster
and storage ring. These reconfigurations only involve
downloading of new signal processing software and will
be performed via EPICS control system. An independent
system for monitoring mechanical drifts of the BPM stations
will be installed as well. The measured data will be
permanently updated in a database and taken into account,
when processing the final electron beam positions.
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| PT19 |
A method for measurement of transverse impedance distribution along storage ring
|
impedance, pick-up, betatron, vacuum |
202 |
| |
- V. Kiselev, V. Smaluk
BINP, Budker Institute of Nuclear Physics, Novosibirsk, Russia
| |
A new method for measurement of transverse couple
impedance distribution along storage ring is described.
The method is based on measuring of a closed orbit
deviation caused by local impedance. Transverse
impedance acts on the beam as a defocusing quadrupole,
strength of which depends on the beam current. If a local
bump of closed orbit has been created at the impedance
location, then the orbit deviation occurs while varying
the beam current. The local impedance can be evaluated
using the orbit deviation measured. Measurement
technique is described, the method accuracy is
evaluated. The method described was successfully used
for measurement of the impedance distribution along the
VEPP-4M storage ring.
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