IBIC2013 - List of Keywords (coupling)

Paper	Title	Other Keywords	Page
MOPC24	Design Of The Stripline BPM For The Advanced Photoinjector Experiment	BPM, impedance, simulation, diagnostics	108
	S. De Santis, M.J. Chin, D. Filippetto, W.E. Norum, Z. Paret, G.J. Portmann, F. Sannibale, R.P. Wells LBNL, Berkeley, California, USA
	Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 We describe the design, bench testing, and initial commissioning of the shorted striplines beam position monitors used in the Advanced Photoinjector Experiment (APEX) at Lawrence Berkeley National Laboratory. Our BPM's are characterized by extreme compactness, being designed to fit in the vacuum chamber of the quadrupole magnets, with only a short portion including the RF feedthroughs occupying additional beam pipe length. In this paper we illustrate the design process, which included extensive 3D computer simulations, the bench testing of prototype and final components, and the first measurements with beam. The readout electronics is also described.

MOPC26	Optimization of Bunch-to-Bunch Isolation in Instability Feedback Systems	feedback, pick-up, kicker, FIR	116
	D. Teytelman Private Address, San Jose, USA
	Bunch-by-bunch feedback formalism is a powerful tool for combating coupled-bunch instabilities in circular accelerators. Imperfections in the analog front and back ends lead to coupling between neighboring bunches. Such coupling limits system performance in both feedback and diagnostic capacities. In this paper, techniques for optimizing bunch-to-bunch isolation within the system will be presented. A new method for improving the performance of the existing systems will be described. The novel approach uses a "shaper" filter in the digital signal processor to compensate for the imperfect response of the power amplifier and kicker combination. An objective optimization method to derive the optimal back end configuration will be presented and illustrated with measurements from several accelerators.
	Poster MOPC26 [0.851 MB]

MOPC32	Development Status of Optical Synchronization for the European XFEL	XFEL, laser, DESY, shielding	135
	C. Sydlo, M.K. Czwalinna, M. Felber, C. Gerth, T. Lamb, H. Schlarb, S. Schulz, F. Zummack DESY, Hamburg, Germany S. Jabłoński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
	Precise timing synchronization on the femtosecond timescale is crucial for time resolved experiments at modern free-electron lasers (FELs) like FLASH and the upcoming European XFEL. The required precision can only be achieved by a laser-based synchronization system. The pulsed laser-based scheme at FLASH, based on the distribution of femtosecond laser pulses over actively stabilized optical fibers, has evolved over the years from a prototype setup to a mature and reliable system. At the same time, the present implementation serves as prototype for the synchronization infrastructure at the European XFEL. Due to a factor of ten increase of the length of the accelerator and an increased number of timing-critical subsystems, new challenges arise. This paper reports on the current development progress of the XFEL optical synchronization, discusses major complications and their solutions.

MOPF32	Development of Gated Turn-by-Turn Position Monitor System for the Optics Measurement During Collision of SuperKEKB	BPM, betatron, controls, optics	295
	M. Tobiyama, H. Fukuma, H. Ishii, K. Mori KEK, Ibaraki, Japan
	Gated turn-by-turn monitor system to measure optics functions using non-colliding bunch has been developed for SuperKEKB accelerators. With the fast, glitch cancelling beam switch, beam position of the target bunch will be measured without affecting the fine COD measurement using narrow-band detectors. The gate timing and the bunch position detection are controlled by the Spartan-6 FPGA. The performance of the system, such as the gate timing jitter, data transfer speed from the system to EPICS IOC and the noise effect to the downstream narrow-band detector are reported.
	Poster MOPF32 [1.531 MB]

TUPC20	Technologies and R&D for a High Resolution Cavity BPM for the CLIC Main Beam	BPM, CLIC, CTF3, pick-up	415
	J.R. Towler, T. Lefèvre, L. Søby, M. Wendt CERN, Geneva, Switzerland S.T. Boogert, F.J. Cullinan, A. Lyapin JAI, Egham, Surrey, United Kingdom
	The Main Beam (MB) LINAC of the Compact Linear Collider (CLIC) requires a beam orbit measurement system with a high spatial (50 nm) and high temporal (50 ns) resolution to resolve the beam position within the 156 ns long bunch train, traveling on an energy-chirped, minimum dispersive trajectory. A 15 GHz prototype cavity BPM has been commissioned in the probe beam-line of the CTF3 CLIC Test Facility. The performance and technical details of this prototype installation are discussed in this paper, including the 15 GHz analog down-converter, the data acquisition and the control electronics and software. An R&D outlook is given for the next steps, which requires a system of 3 cavity BPMs to investigate the full resolution potential.

TUPC28	Strip Line Monitor design for the ISIS Proton Synchrotron using the FEA program HFSS	kicker, impedance, feedback, scattering	435
	S.J. Payne STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	This paper reports the development of a strip line monitor for the ISIS accelerator main ring. The strip line is still in the design phase and the work reported here is the results of the FEA programme HFSS. The strip line will eventually form part of a beam instability feedback system and will be used to control instabilities both in the current ISIS machine and for all future ISIS upgrades where higher intensities and energies could be realised. The strip line consists of two pairs of 550mm by 160mm broad flat electrodes configured to allow damping in both the horizontal and vertical planes. The paper describes the efforts to achieve a bandwidth of >260MHz which will allow the feedback system deal with instabilities such as those caused by electron clouds. Design of the electrodes including matching of the feed throughs to the electrodes , concerns of materials for the electrode supports are considered. Also considered are methods used to improved inter-electrode decoupling (to better than -30db) . Results in the form of scattering parameters, smith charts, time domain reflectivity and shunt impedances will be presented.

TUPC29	Grounded Coplanar Waveguide Transmission Lines as Pickups for Beam Position Monitoring in Particle Accelerators	pick-up, XFEL, simulation, beam-position	438
	A. Penirschke, A. Angelovski, R. Jakoby TU Darmstadt, Darmstadt, Germany C. Gerth, U. Mavrič, D. Nölle, C. Sydlo, S. Vilcins DESY, Hamburg, Germany
	Funding: The work was supported by the MSK group at DESY Hamburg. The authors would like to thank the CST AG for providing the CST Software Package. Energy beam position monitors (EBPM) based on grounded co-planar waveguide (GCPW) transmission lines have been designed for installation in the dispersive sections of the bunch compressor chicanes at the European XFEL. In combination with beam position monitors at the entrance and exit of the bunch compressor chicanes, measurements of the beam energy with single bunch resolution are feasible. The EBPM consists of transversely mounted stripline pickups in a rectangular beam pipe section. The signal detection for the measurement of the phases of the pulses at each end of the pickups is based on the standard down-conversion and phase detection scheme used for the low-level RF-system. A measurement resolution within the lower micrometer range can be achieved for input signal reflections at the pickup of less than -25 dB at 3 GHz. In this paper, simulation results of a novel pickup geometry utilized with GCPW pickup structures and optimized transitions to perpendicular mounted coaxial connectors are presented. The simulation results exhibit small reflection coefficients with reflected signal components having less than 2% of the peak voltage signal.

TUPF14	Description of Laser Transport and Delivery System for the FETS Laserwire Emittance Scanner	laser, diagnostics, emittance, focusing	527
	A. Bosco, G.E. Boorman, S. Emery, S.M. Gibson Royal Holloway, University of London, Surrey, United Kingdom C. Gabor STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom T. Hofmann CERN, Geneva, Switzerland A.P. Letchford STFC/RAL, Chilton, Didcot, Oxon, United Kingdom J.K. Pozimski, P. Savage Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	A beam emittance monitor for H⁻ beams based on laser-induced ions neutralization is being developed at the Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL). The laser system that will be used for the photo-neutralization of the H⁻ beam is a fiber laser emitting 110 ns pulses at λ=1064nm, with a repetition rate of 30 kHz and peak power of 8 kW. The laser will be conveyed to the interaction area over a distance of 70 m via an optical fiber. An assembly of two remotely controlled motorized translation stages will enable the system to scan across the H⁻ beam along its vertical profile. A motorized beam expander will control the output size of the collimated laser beam in order to enable the system to operate with different spatial characteristics of the ions beam. In this paper we present a full account of the laser characteristics, the optical transport system and the final delivery assembly. All the relevant measurements such as power, spatial and temporal characteristics of the laser, fiber transport efficiency and final delivery laser beam parameters will be reported.
	Poster TUPF14 [4.081 MB]

TUPF20	Low Noise and High Dynamic Range Optical Interferometer Beamsize Measurements	emittance, synchrotron, storage-ring, background	550
	M.J. Boland SLSA, Clayton, Australia T.M. Mitsuhashi KEK, Ibaraki, Japan K.P. Wootton The University of Melbourne, Melbourne, Australia
	The technique of optical interferometry to measure beam sizes requires a low noise and high dynamic range digitisation system to push the performance to ultra low emittance on storage rings. The next generation of camera sensor Scientific CMOS (sCMOS) promises to provide the technology to improve optical interferometry. A series of measurements was performed on the Australian Synchrotron storage ring using a sCMOS and a intensity imbalance optical interferometer. The coupling in the storage ring was varied from maximum to minimum using the skew quadrupoles and the beam size at the optical diagnostic beamline was varied from over 100 microns to around 1 micron. A comparison is made between interferometer measurements using the sCMOS with and without an intensity imbalance and with previous measurements using a CCD system.

WEPC07	Development of the RF Front End Electronics for the SIRIUS BPM System	BPM, controls, emittance, electron	670
	R.A. Baron, F.H. Cardoso, S.R. Marques, J.L.B. Neto LNLS, Campinas, Brazil J.-C. Denard SOLEIL, Gif-sur-Yvette, France
	Tight stability requirements for new low emittance light sources, such as SIRIUS being built in Brazil, strongly depend on the BPM RF Front-End performance. Small nonlinearities, uneven temperature drifts and excess noise can spoil the performance of the whole digital BPM system and orbit correction. Calibration and temperature control schemes have been tested in order to suppress position measurement drifts during user beam delivery down to a fraction of micrometer. A method for measuring electronic component nonlinearities at mdB scale is also presented.
	Poster WEPC07 [1.236 MB]

WEPC12	Evaluation of Strip-line Pick-up System for the SPS Wideband Transverse Feedback System	pick-up, SPS, feedback, transverse	690
	G. Kotzian, W. Höfle, R.J. Steinhagen, D. Valuch, U. Wehrle CERN, Geneva, Switzerland
	The proposed SPS Wideband Transverse Feedback system requires a wide-band pick-up system to be able to detect intra-bunch motion within the SPS proton bunches, captured and accelerated in a 200 MHz bucket. We present the electro-magnetic design of transverse beam position pick-up options optimised for installation in the SPS and evaluate their performance reach with respect to direct time domain sampling of the intra-bunch motion. The analysis also discusses the achieved subsystem responses of the associated cabling with new low dispersion smooth wall cables, wide-band generation of intensity and position signals by means of 180 degree RF hybrids as well as passive techniques to electronically suppress the beam offset signal, needed to optimise the dynamic range and position resolution of the planned digital intra-bunch feedback system.

WEPC25	Optimisation of a Split Plate Position Monitor for the ISIS Proton Synchrotron	beam-position, BPM, simulation, proton	739
	C.C. Wilcox, J.C. Medland, S.J. Payne, A. Pertica, M.A. Probert STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	A new Beam Position Monitor (BPM) has been designed for the ISIS proton accelerator facility at the Rutherford Appleton Laboratory in the UK. The new monitor, which will be installed in the beam line to Target 1, is of a ‘split plate’ design which utilises two pairs of electrodes to allow the beam position to be measured simultaneously in the horizontal and vertical planes. Simulations carried out using the CST low frequency solver have highlighted the inaccuracies in the measured beam position caused by strong inter-electrode coupling in such a monitor. This coupling, along with imbalanced electrode capacitances, leads to reduced sensitivity to changes in beam position as well as producing a positional offset error. This paper describes how the problems associated with inter-electrode coupling have been removed with the addition of grounded rings placed between each of the four electrodes. The design and positioning of the rings also ensured that the four electrode capacitances were matched. The results are presented both as CST simulations of ‘thin wire’ beam position measurements and results from bench measurements of a prototype dual plane BPM.

WEPF35	Current Status of the Schottky Cavity Sensor for the CR at FAIR	dipole, shielding, vacuum, simulation	907
	M. Hansli, R. Jakoby, A. Penirschke TU Darmstadt, Darmstadt, Germany P. Hülsmann, W. Kaufmann GSI, Darmstadt, Germany
	Funding: This work was supported by the GSI. The author would like to thank the CST AG for providing CST Studio Suite. In this paper the current status of the Schottky Cavity Sensor development for the Collector Ring at FAIR, a dedicated storage ring for secondary particles, rare isotopes, and antiprotons, is presented. Designed for longitudinal and transversal Schottky signals, the Sensor features a pillbox cavity with attached waveguide filters utilizing the Monopole mode at 200 MHz for longitudinal and the Dipole mode at around 330 MHz for transversal Schottky measurements. Separated coupling structures allow for mode-selective coupling to measure the different Schottky planes independently. A ceramic vacuum shielding inside the pillbox is implemented to enable non-hermetic adjustable coupling, tuning devices and waveguide structures. Simulations of the structure with focus on the impact of the coupling structures and the ceramic vacuum shielding on the R-over-Q values and the coupling are presented as well as measurements of a scaled demonstrator including comparisons with the simulations.

Paper

Title

Other Keywords

Page

MOPC24

Design Of The Stripline BPM For The Advanced Photoinjector Experiment

BPM, impedance, simulation, diagnostics

108

S. De Santis, M.J. Chin, D. Filippetto, W.E. Norum, Z. Paret, G.J. Portmann, F. Sannibale, R.P. Wells
LBNL, Berkeley, California, USA

Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
We describe the design, bench testing, and initial commissioning of the shorted striplines beam position monitors used in the Advanced Photoinjector Experiment (APEX) at Lawrence Berkeley National Laboratory. Our BPM's are characterized by extreme compactness, being designed to fit in the vacuum chamber of the quadrupole magnets, with only a short portion including the RF feedthroughs occupying additional beam pipe length. In this paper we illustrate the design process, which included extensive 3D computer simulations, the bench testing of prototype and final components, and the first measurements with beam. The readout electronics is also described.

MOPC26

Optimization of Bunch-to-Bunch Isolation in Instability Feedback Systems

feedback, pick-up, kicker, FIR

116

D. Teytelman
Private Address, San Jose, USA

Bunch-by-bunch feedback formalism is a powerful tool for combating coupled-bunch instabilities in circular accelerators. Imperfections in the analog front and back ends lead to coupling between neighboring bunches. Such coupling limits system performance in both feedback and diagnostic capacities. In this paper, techniques for optimizing bunch-to-bunch isolation within the system will be presented. A new method for improving the performance of the existing systems will be described. The novel approach uses a "shaper" filter in the digital signal processor to compensate for the imperfect response of the power amplifier and kicker combination. An objective optimization method to derive the optimal back end configuration will be presented and illustrated with measurements from several accelerators.

Poster MOPC26 [0.851 MB]

MOPC32

Development Status of Optical Synchronization for the European XFEL

XFEL, laser, DESY, shielding

135

C. Sydlo, M.K. Czwalinna, M. Felber, C. Gerth, T. Lamb, H. Schlarb, S. Schulz, F. Zummack
DESY, Hamburg, Germany
S. Jabłoński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

Precise timing synchronization on the femtosecond timescale is crucial for time resolved experiments at modern free-electron lasers (FELs) like FLASH and the upcoming European XFEL. The required precision can only be achieved by a laser-based synchronization system. The pulsed laser-based scheme at FLASH, based on the distribution of femtosecond laser pulses over actively stabilized optical fibers, has evolved over the years from a prototype setup to a mature and reliable system. At the same time, the present implementation serves as prototype for the synchronization infrastructure at the European XFEL. Due to a factor of ten increase of the length of the accelerator and an increased number of timing-critical subsystems, new challenges arise. This paper reports on the current development progress of the XFEL optical synchronization, discusses major complications and their solutions.

MOPF32

Development of Gated Turn-by-Turn Position Monitor System for the Optics Measurement During Collision of SuperKEKB

BPM, betatron, controls, optics

295

M. Tobiyama, H. Fukuma, H. Ishii, K. Mori
KEK, Ibaraki, Japan

Gated turn-by-turn monitor system to measure optics functions using non-colliding bunch has been developed for SuperKEKB accelerators. With the fast, glitch cancelling beam switch, beam position of the target bunch will be measured without affecting the fine COD measurement using narrow-band detectors. The gate timing and the bunch position detection are controlled by the Spartan-6 FPGA. The performance of the system, such as the gate timing jitter, data transfer speed from the system to EPICS IOC and the noise effect to the downstream narrow-band detector are reported.

Poster MOPF32 [1.531 MB]

TUPC20

Technologies and R&D for a High Resolution Cavity BPM for the CLIC Main Beam

BPM, CLIC, CTF3, pick-up

415

J.R. Towler, T. Lefèvre, L. Søby, M. Wendt
CERN, Geneva, Switzerland
S.T. Boogert, F.J. Cullinan, A. Lyapin
JAI, Egham, Surrey, United Kingdom

The Main Beam (MB) LINAC of the Compact Linear Collider (CLIC) requires a beam orbit measurement system with a high spatial (50 nm) and high temporal (50 ns) resolution to resolve the beam position within the 156 ns long bunch train, traveling on an energy-chirped, minimum dispersive trajectory. A 15 GHz prototype cavity BPM has been commissioned in the probe beam-line of the CTF3 CLIC Test Facility. The performance and technical details of this prototype installation are discussed in this paper, including the 15 GHz analog down-converter, the data acquisition and the control electronics and software. An R&D outlook is given for the next steps, which requires a system of 3 cavity BPMs to investigate the full resolution potential.

TUPC28

Strip Line Monitor design for the ISIS Proton Synchrotron using the FEA program HFSS

kicker, impedance, feedback, scattering

435

S.J. Payne
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

This paper reports the development of a strip line monitor for the ISIS accelerator main ring. The strip line is still in the design phase and the work reported here is the results of the FEA programme HFSS. The strip line will eventually form part of a beam instability feedback system and will be used to control instabilities both in the current ISIS machine and for all future ISIS upgrades where higher intensities and energies could be realised. The strip line consists of two pairs of 550mm by 160mm broad flat electrodes configured to allow damping in both the horizontal and vertical planes. The paper describes the efforts to achieve a bandwidth of >260MHz which will allow the feedback system deal with instabilities such as those caused by electron clouds. Design of the electrodes including matching of the feed throughs to the electrodes , concerns of materials for the electrode supports are considered. Also considered are methods used to improved inter-electrode decoupling (to better than -30db) . Results in the form of scattering parameters, smith charts, time domain reflectivity and shunt impedances will be presented.

TUPC29

Grounded Coplanar Waveguide Transmission Lines as Pickups for Beam Position Monitoring in Particle Accelerators

pick-up, XFEL, simulation, beam-position

438

A. Penirschke, A. Angelovski, R. Jakoby
TU Darmstadt, Darmstadt, Germany
C. Gerth, U. Mavrič, D. Nölle, C. Sydlo, S. Vilcins
DESY, Hamburg, Germany

Funding: The work was supported by the MSK group at DESY Hamburg. The authors would like to thank the CST AG for providing the CST Software Package.
Energy beam position monitors (EBPM) based on grounded co-planar waveguide (GCPW) transmission lines have been designed for installation in the dispersive sections of the bunch compressor chicanes at the European XFEL. In combination with beam position monitors at the entrance and exit of the bunch compressor chicanes, measurements of the beam energy with single bunch resolution are feasible. The EBPM consists of transversely mounted stripline pickups in a rectangular beam pipe section. The signal detection for the measurement of the phases of the pulses at each end of the pickups is based on the standard down-conversion and phase detection scheme used for the low-level RF-system. A measurement resolution within the lower micrometer range can be achieved for input signal reflections at the pickup of less than -25 dB at 3 GHz. In this paper, simulation results of a novel pickup geometry utilized with GCPW pickup structures and optimized transitions to perpendicular mounted coaxial connectors are presented. The simulation results exhibit small reflection coefficients with reflected signal components having less than 2% of the peak voltage signal.

TUPF14

Description of Laser Transport and Delivery System for the FETS Laserwire Emittance Scanner

laser, diagnostics, emittance, focusing

527

A. Bosco, G.E. Boorman, S. Emery, S.M. Gibson
Royal Holloway, University of London, Surrey, United Kingdom
C. Gabor
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
T. Hofmann
CERN, Geneva, Switzerland
A.P. Letchford
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
J.K. Pozimski, P. Savage
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

A beam emittance monitor for H⁻ beams based on laser-induced ions neutralization is being developed at the Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL). The laser system that will be used for the photo-neutralization of the H⁻ beam is a fiber laser emitting 110 ns pulses at λ=1064nm, with a repetition rate of 30 kHz and peak power of 8 kW. The laser will be conveyed to the interaction area over a distance of 70 m via an optical fiber. An assembly of two remotely controlled motorized translation stages will enable the system to scan across the H⁻ beam along its vertical profile. A motorized beam expander will control the output size of the collimated laser beam in order to enable the system to operate with different spatial characteristics of the ions beam. In this paper we present a full account of the laser characteristics, the optical transport system and the final delivery assembly. All the relevant measurements such as power, spatial and temporal characteristics of the laser, fiber transport efficiency and final delivery laser beam parameters will be reported.

Poster TUPF14 [4.081 MB]

TUPF20

Low Noise and High Dynamic Range Optical Interferometer Beamsize Measurements

emittance, synchrotron, storage-ring, background

550

M.J. Boland
SLSA, Clayton, Australia
T.M. Mitsuhashi
KEK, Ibaraki, Japan
K.P. Wootton
The University of Melbourne, Melbourne, Australia

The technique of optical interferometry to measure beam sizes requires a low noise and high dynamic range digitisation system to push the performance to ultra low emittance on storage rings. The next generation of camera sensor Scientific CMOS (sCMOS) promises to provide the technology to improve optical interferometry. A series of measurements was performed on the Australian Synchrotron storage ring using a sCMOS and a intensity imbalance optical interferometer. The coupling in the storage ring was varied from maximum to minimum using the skew quadrupoles and the beam size at the optical diagnostic beamline was varied from over 100 microns to around 1 micron. A comparison is made between interferometer measurements using the sCMOS with and without an intensity imbalance and with previous measurements using a CCD system.

WEPC07

Development of the RF Front End Electronics for the SIRIUS BPM System

BPM, controls, emittance, electron

670

R.A. Baron, F.H. Cardoso, S.R. Marques, J.L.B. Neto
LNLS, Campinas, Brazil
J.-C. Denard
SOLEIL, Gif-sur-Yvette, France

Tight stability requirements for new low emittance light sources, such as SIRIUS being built in Brazil, strongly depend on the BPM RF Front-End performance. Small nonlinearities, uneven temperature drifts and excess noise can spoil the performance of the whole digital BPM system and orbit correction. Calibration and temperature control schemes have been tested in order to suppress position measurement drifts during user beam delivery down to a fraction of micrometer. A method for measuring electronic component nonlinearities at mdB scale is also presented.

Poster WEPC07 [1.236 MB]

WEPC12

Evaluation of Strip-line Pick-up System for the SPS Wideband Transverse Feedback System

pick-up, SPS, feedback, transverse

690

G. Kotzian, W. Höfle, R.J. Steinhagen, D. Valuch, U. Wehrle
CERN, Geneva, Switzerland

The proposed SPS Wideband Transverse Feedback system requires a wide-band pick-up system to be able to detect intra-bunch motion within the SPS proton bunches, captured and accelerated in a 200 MHz bucket. We present the electro-magnetic design of transverse beam position pick-up options optimised for installation in the SPS and evaluate their performance reach with respect to direct time domain sampling of the intra-bunch motion. The analysis also discusses the achieved subsystem responses of the associated cabling with new low dispersion smooth wall cables, wide-band generation of intensity and position signals by means of 180 degree RF hybrids as well as passive techniques to electronically suppress the beam offset signal, needed to optimise the dynamic range and position resolution of the planned digital intra-bunch feedback system.

WEPC25

Optimisation of a Split Plate Position Monitor for the ISIS Proton Synchrotron

beam-position, BPM, simulation, proton

739

C.C. Wilcox, J.C. Medland, S.J. Payne, A. Pertica, M.A. Probert
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

A new Beam Position Monitor (BPM) has been designed for the ISIS proton accelerator facility at the Rutherford Appleton Laboratory in the UK. The new monitor, which will be installed in the beam line to Target 1, is of a ‘split plate’ design which utilises two pairs of electrodes to allow the beam position to be measured simultaneously in the horizontal and vertical planes. Simulations carried out using the CST low frequency solver have highlighted the inaccuracies in the measured beam position caused by strong inter-electrode coupling in such a monitor. This coupling, along with imbalanced electrode capacitances, leads to reduced sensitivity to changes in beam position as well as producing a positional offset error. This paper describes how the problems associated with inter-electrode coupling have been removed with the addition of grounded rings placed between each of the four electrodes. The design and positioning of the rings also ensured that the four electrode capacitances were matched. The results are presented both as CST simulations of ‘thin wire’ beam position measurements and results from bench measurements of a prototype dual plane BPM.

WEPF35

Current Status of the Schottky Cavity Sensor for the CR at FAIR

dipole, shielding, vacuum, simulation

907

M. Hansli, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
P. Hülsmann, W. Kaufmann
GSI, Darmstadt, Germany

Funding: This work was supported by the GSI. The author would like to thank the CST AG for providing CST Studio Suite.
In this paper the current status of the Schottky Cavity Sensor development for the Collector Ring at FAIR, a dedicated storage ring for secondary particles, rare isotopes, and antiprotons, is presented. Designed for longitudinal and transversal Schottky signals, the Sensor features a pillbox cavity with attached waveguide filters utilizing the Monopole mode at 200 MHz for longitudinal and the Dipole mode at around 330 MHz for transversal Schottky measurements. Separated coupling structures allow for mode-selective coupling to measure the different Schottky planes independently. A ceramic vacuum shielding inside the pillbox is implemented to enable non-hermetic adjustable coupling, tuning devices and waveguide structures. Simulations of the structure with focus on the impact of the coupling structures and the ceramic vacuum shielding on the R-over-Q values and the coupling are presented as well as measurements of a scaled demonstrator including comparisons with the simulations.