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| IT02 | Overview of the Diagnostics Systems of SOLEIL and DIAMOND | diagnostics, instrumentation, sychrotron radiation, feedback, SOLEIL, DIAMOND | 6 | ||
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SOLEIL and DIAMOND are two third-generation light sources in construction
in France and in Great Britain respectively. SOLEIL is scheduled to
deliver its first photons to its users in 2006 and DIAMOND in 2007. This
talk will present the beam diagnostic systems of both projects with
emphasizing technological novelties and the instruments that are
essential to their performances: BPM system, profile monitors and
feedback systems.
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| CT01 | An Inductive Pick-Up for Beam Position and Current Measurements | instrumentation, CLIC | 53 | ||
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An Inductive Pick-Up (IPU) senses the azimuthal distribution of the beam
image current. Its construction is similar to a wall current monitor, but
the pick-up inner wall is divided into electrodes and each of which forms
the primary winding of a toroidal transformer. The beam image current
component flowing along each electrode is transformed to a secondary
winding, connected to a pick-up output. Four pick-up output signals drive
an active hybrid circuit, producing two difference signals proportional
to the horizontal and vertical beam positions, and one sum signal,
proportional to the beam current. The bandwidth of these signals, ranging
from below 1 kHz to beyond 150 MHz, exceeds five decades. Each electrode
transformer has an additional turn to which a pulse from a precise
current source is applied to calibrate the sensor for accurate beam
position and current measurements. The IPU has been developed for the
drive beam linac of the CLIC Test Facility 3. For that purpose it had to
be optimized for low longitudinal coupling impedance in the GHz range.
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| PM26 | A System For Beam Diagnostics in the External Beam Transportation Lines of the DC-72 Cyclotron | diagnostics, instrumentation, cyclotron, medical accelerators, emittance, DC-72 | 155 | ||
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The isochronous four-sector Cyclotron DC-72 will serve as the basic
facility of the Cyclotron Center of the Slovak Republic in Bratislava. It
will be used for accelerating ion beams of H- to Xe up to energy of
72-2.7 MeV/nucleon.
In the present work a system for external beam diagnostics is presented,
which is intended for on-line acquisition of data on the main parameters
of accelerated beams (current, position, profile, emittance and energy
of the ion beams) to allow effective tuning of the accelerator operation
regime as well as ion beam transport along the transport lines through
the ion optical systems to physical targets and set-ups.
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| PT01 | Beam Position And Phase Measurements Using A FPGA For The Processing Of The Pick-Ups Signals | diagnostics, storage-ring | 169 | ||
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We have implemented the signal processing needed to derive the transverse
beam position and the beam phase from the signals of a four electrodes
BPM block on a FPGA (field programmable gate array). The high processing
rate of a FPGA allows taking the full benefit of the high data
acquisition rate of the most recent ADC circuits. In addition, it is
possible to implement on a FPGA a processing algorithm exactly tailored
to the measurement of the beam parameters. The efficiency of the signal
processing has also been improved by a careful choice of the frequency of
the sampling clock and of the RF front-end local oscillator, which are
derived from the storage ring RF frequency. This paper describes the BPM,
the RF front-end electronics and the FPGA algorithm. It presents some of
the application of this BPM at ESRF and gives measurement results.
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| PT06 | Dynamic X-Y Crosstalk / Aliasing Errors of Multiplexing BPMs | instrumentation, diagnostics, monitoring, operational-performance, controls, feedback | 181 | ||
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Multiplexing Beam Position Monitors (BPM) are widely used for their
simplicity and inherent drift cancellation property. These systems
successively feed the signals of (typically four RF) pickups through one
single detector channel. The beam position is calculated from the
demultiplexed (base band) signal. However, as shown by this contribution,
transverse beam motion results in positional aliasing errors due to the
finite multiplexing frequency. Fast horizontal motion, for example, can
alias into an apparent, slow vertical position change. A thorough
analysis is presented and the impact of essential parameters such as the
multiplexing rate and the scanning pattern/sequence of classical 4-button
pickups is discussed.
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| PT13 | An X-Band Cavity for a High Precision Beam Position Monitor
Work supported by Dept. of Energy Contract DE-AC03-76F00515 |
beam position, diagnostics, instrumentation, NLC | 196 | ||
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The next generation of accelerators will require increasingly precise
control of beam position. For example designs for the next linear
collider require beam-position monitors (BPMs) with 200 nm resolution.
The accelerator designs also place difficult requirements on accuracy and
stability. To meet these requirements a cavity BPM operating at 11.424
GHz was designed. The BPM consists of two cavities: an xy-cavity tuned to
the dipole mode and a phase cavity tuned to the monopole mode. The
xy-cavity uses a novel coupling scheme that (in principal) has zero
coupling to the monopole mode. This report will present the mechanical
design, simulations, and test results of a prototype BPM. In addition BPM
designs with even higher precision will be discussed.
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| PT14 | Design of BPM PU for Low-Beta Proton Beam Using Magic Code | proton linac, BPM, MAGIC code, simulation, sensitivity | 199 | ||
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We have designed the BPM PU based on capacitive buttons for use in the
KOMAC (Korea Multi-purpose Accelerator Complex), the high-intensity
proton linac that are under development at the KAERI (Korea Atomic
Research Institute), Korea. The KOMAC is aiming to produce CW 20 mA beam
current at the 100 MeV energy. We have chosen the button-type PU since it
is easier to fabricate than other type PUs including the stripline, and
it could provide enough signal power because of the high beam current.
The PU sensitivity was calculated by the MAGIC that is a kind of the
Particle-In-Cell code that originates from the plasma science community.
The utilization of the MAGIC code is especially useful for BPM PUs in the
low-beta sections of the accelerator, because it is difficult to obtain
the PU sensitivity experimentally due to the difficulties in simulating
the low-beta beams by the electromagnetic waves in a test bench. In this
presentation, we report on the design of the BPM PU based on the MAGIC
calculation.
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| PT15 | Performance of the ELBE BPM Electronics | diagnostics, instrumentation, linac, monitoring, ELBE | 202 | ||
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The ELBE radiation source is based on a superconducting linac. Initially
it was designed to be used in CW mode with repetition rates either 13 MHz
either 260 MHz. Later it was decided to operate the accelerator with
reduced repetition rates for diagnostic reasons and for certain users.
Now it is possible to operate at repetition rate 13/n MHz, where n can be
2, 4, 8, 16, 32, 64, and 128. It is required that the BPM system supports
any of these operation modes. A core element of the BPM electronics is a
logarithmic amplifier AD8313 made by Analog Devices Inc. The logarithmic
amplifier is a direct RF to DC converter rated up to 2.5 GHz. Initial
design of the BPM electronic was sophisticated only for CW operation with
repetition rate more than 10 MHz, since bandwidth of the AD8313 is
about of 10 MHz. Additionally a sample and hold amplifier is built in to
provide enough time for an ADC to make measurements. The sample and hold
amplifier is synchronized with a micropulse frequency. In the paper we
present results of the modified BPM electronics test.
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| PT19 | Transverse Feedback System For The Cooler Synchrotron COSY-Jülich - First Results | storage-ring, synchrotron, beam cooling, beam-losses, coherent-effects, damping, feedback, kicker | 214 | ||
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The cooler synchrotron COSY delivers unpolarized and polarized protons
and deuterons in the momentum range 300 MeV/c up to 3.65 GeV/c. Electron
cooling at injection level and stochastic cooling covering the range from
1.5 GeV/c up to maximum momentum are available to prepare high precision
beams for internal as well as for external experiments in hadron physics.
In case of electron cooled beam the intensity is limited by transverse
instabilities. The major losses are due to the vertical coherent beam
oscillations. To damp these instabilities a transverse feedback system is
under construction. First results with a simple feedback system are
presented. Due to the feedback system operation the intensity and
lifetime of the electron cooled proton beam at injection energy could be
significantly increased. Measurements in frequency and time domain
illustrate the performance of the system.
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| PT26 | Cryogenic Current Comparator for Absolute Measurement of the Dark Current of the Superconducting Cavities for Tesla | cryogenics, diagnostics, monitoring, shielding, superconductivity, TESLA | 234 | ||
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A newly high performance SQUID based measurement system for detecting
dark currents, generated by superconducting cavities for TESLA is
proposed. It makes use of the Cryogenic Current Comparator principle and
senses dark currents in the nA range with a small signal bandwidth of 70
kHz.
To reach the maximum possible energy in the TESLA project is a strong
motivation to push the gradients of the superconducting cavities closer
to the physical limit of 50 MV/m. The field emission of electrons (the so
called dark current) of the superconducting cavities at strong fields may
limit the maximum gradient. The absolute measurement of the dark current
in correlation with the gradient will give a proper value to compare and
classify the cavities.
This contribution describes a Cryogenic Current Comparator (CCC) as an
excellent and useful tool for this purpose. The most important component
of the CCC is a high performance DC SQUID system which is able to measure
extremely low magnetic fields, e.g. caused by the extracted dark current.
For this reason the SQUID input coil is connected across a special
designed pick-up coil for the electron beam. Both the SQUID input coil
and the pick-up coil form a closed superconducting loop so that the CCC
is able to detect dc currents down to 2 pA/√Hz. Design issues and the
application for the CHECHIA cavity test stand at DESY as well as
preliminary experimental results are discussed.
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| PT28 | Current Measurements of Low-Intensity Beams at CRYRING | storage-ring, diagnostics | 240 | ||
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The demand for new ion species leads to an increasing number of cases in
which the ions can only be produced in small quantities. Thus, weak ion
currents quite often have to be handled in low energy ion storage ring,
like CRYRING. Various detector systems have been developed to measure
such low intensity coasting and bunched beams by using the overlapping
ranges of those systems.
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