BPMs and Beam Stability
Paper Title Page
MOPB049 An Optical Intra-Bunch Instability Monitor for Short Electron Bunches 161
 
  • T.G. Lucas, P.J. Giansiracusa, D.J. Peake, R.P. Rassool
    The University of Melbourne, Melbourne, Victoria, Australia
  • M.J. Boland
    ASCo, Clayton, Victoria, Australia
  • R.J. Steinhagen
    GSI, Darmstadt, Germany
  
  An improved understanding of intra-bunch instabilities in synchrotron light source electron bunches is crucial to overcoming the imposed limitations of the achievable intensity. A Multiband Instability Monitor, designed specifically for the short bunches of a synchrotron light source, has been developed to perform measurements of intra-bunch dynamics. The MIM performs real-time measurements at a diagnostic beamline using optical synchrotron radiation incident on a high speed photodetector. Three frequency bands up to 12 GHz were used to identify characteristic frequency signatures of intra-bunch instabilities. Mixed to baseband using RF detectors, these high frequency measurements can be performed without the need for similarly high frequency digitisers. This paper reports on the performance of the system at the Australian Synchrotron.  
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TUBLA01 Beam Based Calibration for Beam Position Monitors 266
 
  • M. Tejima
    KEK, Ibaraki, Japan
  
  Beam position monitoring is one of most fundamental diagnostic tool in accelerator. To keep good performance of the BPM system, the beam-based alignment method is developed and used for more precise BPM alignment and keeping the performance. The signal from BPM is transfer by coaxial cable, and processed by signal processing circuit. The beam position is calculating from the relative ratio between the 4 intensities from the BPM head. The characteristic of circuit gain is calibrated in the beginning by using the test bench. But this calibration will be changed with passing year. To escape from this problem, a same kind of calibration for the gain as like as beam-based alignment is key issue to maintain a good performance of the BPM system. For this propose, a beam-based gain calibration method is developed and used in the KEK. The both of beam-based alignment method and beam based gain calibration method present using concrete examples.  
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TUBLA03
 Status of the Intra-bunch Feedback at J-PARC Main Ring  
 
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y.H. Chin, T. Koseki, H. Kuboki, T. Obina, M. Okada, M. Tobiyama
    KEK, Ibaraki, Japan
  • K.G. Nakamura
    Kyoto University, Kyoto, Japan
  • Y. Shobuda
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  
  Funding: This work is partially supported by MEXT KAKENHI Grant Number 25105002, "Grant-in-Aid for Scientific Research on Innovative Areas titled Unification and Development of the Neutrino Science Frontier"
One of the present obstacles for intensity upgrade of the J-PARC Main Ring is transverse collective instability. We have been developing so called intra-bunch feedback system and in operation during injection flat bottom since last year. But recent beam intensity upgrade push us to improve further the system, namely feedback during acceleration. The revolution frequency changes about 2% and the synchronous phase varies 0 - 26 degree during acceleration from 3 to 30 GeV in the MR. The delay in the feedback loop is changed stepwise triggered by external pulses. We are examining quick trigger timing determination by matching the bunch shape in the controller ("iGp12") to the one from the exciter (kicker) and estimating differences of slice markers in time. This method is time saving, which is important because of a limited machine tuning time. We will report present status of the feedback during acceleration. 		 
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TUBLA04 Progress Towards Electron-Beam Feedback at the Nanometre Level at the Accelerator Test Facility (ATF2) at KEK 273
 
  • P. Burrows, D.R. Bett, N. Blaskovic Kraljevic, T. Bromwich, G.B. Christian, M.R. Davis, C. Perry
    JAI, Oxford, United Kingdom
  
  Ultra-low latency beam-based digital feedbacks have been developed by the Feedback On Nanosecond Timescales (FONT) Group and tested at the Accelerator Test Facility (ATF2) at KEK in a programme aimed at beam stabilisation at the nanometre level at the ATF2 final focus. Three prototypes were tested: 1) A feedback system based on high-resolution stripline BPMs was used to stabilise the beam orbit in the beamline region c. 50m upstream of the final focus. 2) Information from this system was used in a feed-forward mode to stabilise the beam locally at the final focus. 3) A final-focus local feedback system utilising cavity BPMs was deployed. In all three cases the degree of beam stabilisation was observed in high-precision cavity BPMs at the ATF2 interaction point. Latest results are reported on stabilising the beam position to approximately 50nm.  
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TUPB002 Fast Orbit Feedback System at SLSA 293
 
  • Y.E. Tan, N.J. Basten, T.D. Cornall, E. Joseph Vettoor
    SLSA, Clayton, Australia
  • A. Michalczyk
    ASCo, Clayton, Victoria, Australia
  • D.J. Peake
    The University of Melbourne, Melbourne, Victoria, Australia
  
  Since the end of commissioning of the facility in 2006, implementing topup (completed 2012) and fast orbit feedback have been top priority upgrades to improve the stability of the light source for users. The fast orbit feedback system is currently being implemented and will be commissioned in 2016. The feedback system has a star topology with an FPGA based feedback processor at its core. The system will utilises the existing 98 Libera Electron beam position processors, with Libera Grouping for data aggregation, as the source of postion data at 10 kHz. The corrections are calculated in a Xilinx Vertex 6 FPGA and is transmitted to 14 corrector power supplies in the 14 sectors. These power supplies are six-channel bipolar 1 Ampere and have been developed by a local company. The corrector magnets are tertiary coils on the existing sextupole magnets in the storage ring. This report shall present the design, results of Simulink simulations, the current status of implementation and future plans.  
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TUPB005 Advancements in the Management Measurements & Visualisation of NEC Beam Profile Monitors 298
 
  • D.T. Button, D.B. Garton, M.C. Mann
    ANSTO, Menai, New South Wales, Australia
  • S. Yan
    NI, Macquarie Park, New South Wales, Australia
  
  In DC ion beam tandem accelerator facilities commonly Helix Rotating wire Beam Profile Monitors (BPM) are used to monitor the shape and location of the beam. These BPM's are used in combination with a BPM Selection station which activates and conditions signals for display on an Oscilloscope for visualization. At ANSTO we have been developing an alternative system to allow management of concurrent off the shelf NEC BPM's, and to construct a 2D approximation of the particle beam based on programmable hardware and software. This paper will review the current status of the development, and the potential features which can be gained with this technological approach.  
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TUPB006 Impedance Optimization of Sirius Stripline Kicker 302
 
  • H.O.C. Duarte, S.R. Marques
    LNLS, Campinas, Brazil
  
  Two approaches to design a transverse feedback (TFB) stripline kicker are well known in the accelerators community: one with bare strips in a tapered cavity and other whose shrouded strips are ended with parallel-plate capacitive gaps. This work presents a comparison between both models in terms of electromagnetic performance, proposes alternative solutions for increasing the gap capacitance and analyzes the performance of a hybrid stripline kicker design.  
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TUPB009 A New Beam Angle Interlock at Soleil 318
 
  • N. Hubert, Y.-M. Abiven, L. Cassinari, L. Chapuis, F. Dohou, M.E. El Ajjouri, A. Loulergue, O. Marcouillé, P. Monteiro, L.S. Nadolski, D. Pédeau, P. Rommeluère
    SOLEIL, Gif-sur-Yvette, France
  
  Anatomix and Nanoscopium beamlines are collecting photons generated by two 5.5 mm gap in-vacuum insertion devices installed in a canted straight section. Simultaneous operation of those two beamlines requires particular precautions in terms of alignment of the electron (and photon) beam in the undulators. With the high stored beam current (500 mA), any mis-steering in the upstream undulator could quickly damage the downstream one. Using the classical beam position interlock to guarantee the undulators protection would have constrained too much the operation due to very restrictive position thresholds. Then the machine protection system has been modified to incorporate a new interlock based on the electron beam angle combining two BPM readings. A description of the system and its performances will be presented.  
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TUPB010 Digital Processing of Pick-up Signals for Position and Tune Determination 321
 
  • R. Singh, P. Forck, P. Kowina, A. Reiter
    GSI, Darmstadt, Germany
  
  With the advent of fast high resolution Analog to Digital Converters (ADCs) and Field Programmable Gate Arrays (FPGAs), 'all digital systems' for pick-up data processing to calculate position and tune have become commonplace. The flexibility of these digital systems is very advantageous since it permits the change of position determination algorithms based on beam conditions, accelerator operation modes and measurement requirements. This contribution compares the frequently used position determination algorithms in terms of measurement variance, bias, robustness and computational complexity using simple analytical model. The analytical model is compared to the beam data to evaluate its applicability and conclusions on the optimum position estimator are derived.  
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TUPB014 Development Status and Performance Studies of the New MicroTCA Based Button and Strip-line BPM Electronics at FLASH 2 335
 
  • B. Lorbeer, N. Baboi, H.T. Duhme, F. Schmidt-Föhre, K. Wittenburg
    DESY, Hamburg, Germany
  
  The FLASH (Free Electron Laser in Hamburg) facility at DESY (Deutsches Elektronen-Synchrotron) in Germany has been extended by the new undulator line FLASH2 providing twice as many experimental stations for users in the future. After the acceleration of the electron bunch train up to 1.2GeV in FLASH, a part of the beam can be kicked into FLASH2, while the other is going to the old undulator line of FLASH I. The commissioning phase of FLASH2 started in early 2014 and is continued parasitically during user operation in FLASH1. One key point during first beam commissioning is the availability of standard diagnostic devices such as Beam Position Monitors (BPMs). In the last couple of years new electronics for button and strip-line BPMs have been developed, based on the MTCA.4 standard. This new Low Charge BPM (LCBPM) system is designed to work with bunch charges as small as 100 pC in contrast to the old systems at FLASH initially designed for bunch charges of 1nC and higher. This paper summarizes the performance of the BPM system and discusses the applied methods based on beam based correlation techniques to study the system.  
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TUPB015 Development of New Beam Position Monitors at COSY 339
 
  • F. Hinder, H. Soltner, F. Trinkel
    FZJ, Jülich, Germany
  • H.-J. Krause
    Forschungszentrum Jülich, Peter Gruenberg Institut, Jülich, Germany
  
  Electric Dipole Moments (EDM) violate parity and time reversal symmetries. Assuming the CPT-theorem, this leads to CP violation, which is needed to explain the matter over antimatter dominance in the Universe. Thus, a non-zero EDM is a hint to new physics beyond the Standard Model. The JEDI collaboration (Jülich Electric Dipole moment Investigations) has started investigations of a direct EDM measurement of protons and deuterons at a storage ring. To measure a tiny EDM signal with high precision, systematic effects have to be controlled to the same level. One way of controlling systematic effects is the use of new Beam Position Monitors. The idea is based on the usage of magnetic pick-ups in a Rogowski coil configuration. The main advantage of the coil design is the high response to a high frequency signal, the particle bunch frequency, and the compactness of the coil itself. In a first step the BPMs will be benchmarked in a laboratory test system. In the next step the calibrated BPMs will be installed and tested at the conventional storage ring COSY (Cooler Synchrotron) at Jülich. At the conference first measurement results and the upcoming developments will be presented.  
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TUPB017 Studies for a BPM Upgrade at COSY 347
 
  • C. Böhme, M. Bai, F. Hinder, V. Kamerdzhiev, F. Trinkel
    FZJ, Jülich, Germany
  
  For the planned Electric Dipole Moment (EDM) precursor experiment at the COSY synchrotron and storage ring an accurate control of the beam orbit is crucial. The required beam position measurement accuracy demands an upgrade of the BPM readout electronics. The BPM system currently in operation is described. The required performance and the possible upgrade scenarios are discussed.  
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TUPB018 Compact and Complete Beam Diagnostic System for HCI at IUAC 351
 
  • R.V. Hariwal, S. Kedia, R. Mehta
    IUAC, New Delhi, India
  • H.K. Malik
    Indian Institute of Technology, New Delhi, India
  • V.A. Verzilov
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  
  Funding: University Grants Commission, India
Design efforts result into the fabrication of a compact and complete beam diagnostic system for High Current Injector (HCI) accelerator system at Inter-University Accelerator Centre (IUAC), New Delhi, India. HCI is an upcoming accelerator facility and will be used as an injector to the existing SC-LINAC. It consists of high temperature superconducting Electron Cyclotron Resonance (HTS-ECR) ion source, normal temperature Radio Frequency Quadrupole (RFQ), IH-type Drift Tube Linear (DTL) resonators and low beta superconducting quarter wave resonator cavities to accelerate heavy ions having A/q ≤ 6. The diagnostic system is especially designed and fabricated to get the complete beam information like current, profile, position, transverse and longitudinal emittances, bunch length and energy of incident ion beam at the entrance of DTL resonators. The compactness is preferred to minimize the transverse and longitudinal emittance growth at the entrance of DTL resonators. Various beam parameters of heavy ion beams at different energy have been carried out to validate the design and fabrication of the system. Here, the design, fabrication and various test results are presented. 		 
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TUPB019 Design and Development of Configurable BPM Readout System for ILSF 354
 
  • M.Sh. Shafiee, M. Jafarzadeh, J. Rahighi
    ILSF, Tehran, Iran
  • A.H. Feghhi
    Shahid Beheshti University, Tehran, Iran
  
  A configurable electronic system has been developed for button BPMs readout in the storage ring of Iranian Light Source Facility (ILSF). This system calculates the beam position through the output voltage of BPMs. Output signals of BPMs pass through a 500 MHz and 50ohm front-end for noise filtering and also gain control purposes. Then the signal is digitized based on under sampling method by a 130MHz ADC for further analysis in FPGA. Safe dynamic range of 0dBm to -90 dBm can be covered by this electronic system with white noise measured to be around -110dBm. Trigger for this electronic is 2-10Hz as Slow data acquisition for Slow orbit feedback system and 4-10KHz as Fast data acquisition for fast orbit feedback system. This paper describes the design, analysis, and measurements of the developed electronic system.  
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TUPB020 Long-Term Stability of the Beam Position Monitors at SPring-8 359
 
  • T. Fujita, H. Dewa, M. Masaki, S. Matsubara, S. Sasaki, S. Takano
    JASRI/SPring-8, Hyogo-ken, Japan
  • H. Maesaka, Y. Otake
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  
  At the SPring-8 storage ring, the renewal of BPM electronics in 2006 has improved orbit feedback resolution *. However, a stability issue of the whole BPM system, including the buttons, the cables and the electronics, remains to be settled for long-term stability of the beam orbit. The BPM in the present SPring-8 has gain imbalances among 4 electrode channels, which result in large offsets (~1 mm). The imbalances are routinely corrected in accordance with a beam-based measurement **. But, the offset error increases close to 100 um during the operation, because of the imbalance fluctuations. Major origin of the imbalances is standing waves caused by reflections in BPM cables. As a countermeasure for the imbalance issue, isolators to mitigate the standing waves were equipped. They significantly reduced the imbalances, but not sufficient to completely suppress the imbalance fluctuations. The requirement of stability for the BPM system for the upgrade plan of SPring-8 is going to be more stringent. We started extensive survey to find the sources of fluctuations of the gain imbalances in order to achieve long-term stability of the BPM system applicable to the planned SPring-8 upgrade.
* S. Sasaki, T. Fujita et al., Proc. of the DIAPC 2007, Venice, Italy, (2007) p. 114
** M. Masaki et al., Proc. of the 11th Symp. on Accel. Sci. and Technol., (1997), p.83.
 		 
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TUPB023 High Position Resolution BPM Readout System with Calibration Pulse Generators for KEK e+/e− Linac 369
 
  • F. Miyahara, K. Furukawa, M. Satoh, Y. Seimiya, T. Suwada
    KEK, Ibaraki, Japan
  • R. Ichimiya
    JAEA, Aomori, Japan
  • H.S. Saotome
    Kanto Information Service (KIS), Accelerator Group, Ibaraki, Japan
  
  The KEK e+/e− injector linac will be operated in multiple modes for the electron beam injection to 3 independent storage rings, SuperKEKB HER, Photon Factory (PF) Ring and PF-AR, and the positron beam injection into the damping ring and the SuperKEKB LER. The operation modes can be switched every 20 milliseconds. The injector linac is under upgrade for the SuperKEKB, where the required resolution of beam position measurement is less than 10 micrometer. However, the current system based on oscilloscopes for stripline beam position monitors (BPMs) has the position resolution of 50 micrometers approximately. Thus, we have developed a new BPM readout system with narrow band pass filter, 16-bit, 250 MSa/s ADCs and calibration pulse generators. The system is based on VME standard and the beam position is calculated by FPGA on board. The new system has the position resolution of 3 micrometer and wide dynamic range from 0.1 to 10 nC/bunch. The calibration pulse follows every position measurement. The calibration pulse is used for the gain correction and the integrity monitor of the cable connection. We will report details of the system.  
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TUPB026 Machine Stability Analysis by Pulse Based Data Archiver of the J-PARC RCS 381
 
  • N. Hayashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  
  The J-PARC RCS (Rapid-Cycling proton Synchrotron) runs with repetition rate of 25 Hz. The beam intensity of current monitors and beam loss monitors (BLM) data are archived for all pulses and they could be analyzed to study the machine stability. In addition BPM data are also recorded in regularly (2 seconds with every minutes) and particularly in case of the RCS MPS, the last several hundreds BPM data are recorded. We will report a few examples, in the case of magnet feedback problem or vacuum problem, how the BPM or BLM behaves.  
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TUPB028 Status of BPMs In the First Stage of Commissioning at CADS Injector I 390
 
  • H.Z. Ma, J.S. Cao, Y.F. Sui, Q. Ye
    IHEP, Beijing, People's Republic of China
  
  The paper will introduce the status for BPMs in the first stage of commissioning at CADS (China Accelerator Driven Subcritical System) Injector I. The measurement principles and results of BPM at injector I are presented. The measurement of BPM is rigorous in the first medium energy beam transport line of CADS Injector I. To ensure the safety of test cryomodule, beam orbit should be corrected to the minimized region. The third order fitting way is used to calculate the position of beam for BPM non-linearity. And the average of data in the single pass window should improve the resolution. Then BBA of BPM can help tracking beam position accurately. Finally the interlock circuit of BPM is tested with the beam.
[1]Jingyu Tang etc, IHEP-CADS Report/2012-01E
[2]Libera SPH page - http://www.i-tech.si/
[3]Weimin Pan, Internal Report in IHEP.
[4]Libera Single Pass H User Manual 2.80 		 
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TUPB035 Bunch-by-Bunch Study of the Transient State of Injection at the SSRF 396
 
  • Z.C. Chen, Y.B. Leng
    SSRF, Shanghai, People's Republic of China
  
  Funding: National Natural Science Foundation of China (No. 11305253)
High current and stable beams are preferred to a light source, so the suppression of the oscillations due to the frequent injections during top-off operations get the attention at the Shanghai Synchrotron Radiation Facility (SSRF). To evaluate the possibility of further optimizations, a bunch-by-bunch position monitor is used to study the behavior of the injected bunch. The injected part is isolated from the stored one by decomposing the position matrix of all the bunches in the storage ring. Frequency feature, motion lifetime and other characteristic parameters of the injection mode have been compared with those of the stored mode. 		 
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TUPB036 Progress of Cavity Beam Position Monitor at SXFEL 399
 
  • L.W. Lai, Z.C. Chen, Y.B. Leng, Y.B. Yan, L.Y. Yu, R.X. Yuan, W.M. Zhou
    SSRF, Shanghai, People's Republic of China
  
  Shanghai Soft X-ray FEL Test Facility (SXFEL) has started the infrastructure construction in 2015. All beam diagnostic systems are under processing and measurement, including C-band Low-Q cavity BPMs. This paper presents the progress of the cavity BPM system, including design and the measurements on a lab platform. Measurements shown that the cavity BPM frequency is 4.7GHz±8MHz, and the complete test platform verify that the cavity BPM system, which including signal processing electronics can work as expected.
* Work supported by National Natural Science Foundation (No. 11305253, 11375255)
 		 
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TUPB041 Development of Capacitive Linear-Cut Beam Position Monitor for Heavy-Ion Synchrotron of KHIMA Project 405
 
  • J.G. Hwang, S.Y. Noh
    KIRAMS/KHIMA, Seoul, Republic of Korea
  • P. Forck
    GSI, Darmstadt, Germany
  • C. Kim
    PAL, Pohang, Kyungbuk, Republic of Korea
  • T.K. Yang
    KIRAMS, Seoul, Republic of Korea
  
  particles for the carbon beams and ~ ∼  2.07 × 10zEhNZeHn for the proton beams, the linear-cut beam position monitor is adopted to satisfy the position resolution of 100 μm and accuracy of 200 μm with the linearity within the wide range. In this paper, we show the electromagnetic design of the electrode and surroundings to satisfy the resolution of 100 μm, the criteria for mechanical aspect to satisfy the position accuracy of 200 μm, the measurement results of position accuracy and calibration by using wire test-bench, and the beam-test results with long ( ∼  1.6 μs) electron beam in pohang accelerator laboratory (PAL).  
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TUPB046 Integration of the Diamond Transverse Multibunch Feedback System at ALBA 414
 
  • A. Olmos, U. Iriso, J. Moldes, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • M.G. Abbott, G. Rehm, I.S. Uzun
    DLS, Oxfordshire, United Kingdom
  
  A Transverse Multi-Bunch Feedback system (TMBF) has been commissioned at the ALBA storage ring for stabilization of the beam instabilities. The system is based on the Libera Bunch-By-Bunch electronics, controlled using a specific software developed at Diamond Light Source. This system refurbishes the existing FPGA code to include several features for machine studies, like fast and precise tune measurements using a Phase Locked Loop, sequences of grow-damp experiments that allow measuring damping rates on a mode-by-mode basis, and precise bunch cleaning. We describe the TMBF system and the integration of the control software into the ALBA machine. Finally we show examples of beam stabilization and machine studies using this system.  
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TUPB047 Electrostatic Finite-element Code to Study Geometrical Nonlinear Effects of BPMs in 2D 418
 
  • A.A. Nosych, U. Iriso
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • J. Olle
    UAB, Barcelona, Spain
  
  We have developed a 2D finite element-based software for Matlab to study non-resonant effects in BPMs of arbitrary geometry, in particular the geometric nonlinearities. The developed code called BpmLab utilizes an open-source tetrahedral mesh generator DistMesh, combined with a short implementation of FEM with linear basis functions to find the electrostatic field distribution for boundary electric potential excitation. The BPM response as a function of beam position is calculated in a single simulation for all beam positions using the potential ratios, according to the Green's reciprocity theorem. The code offers ways to correct the geometrical nonlinear distortion, either by polynomials or by direct inversion of the electrode signals through numerical optimization. This work is an overview of the BpmLab capabilities to date, including its extensive benchmarking and validation against other methods  
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TUPB048 Measurements and Calibration of the Stripline BPM for the ELI-NP facility with the Stretched Wire Method 423
 
  • A.A. Nosych, C. Colldelram, A. Crisol, U. Iriso, A. Olmos
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • F. Cioeta, A. Falone, A. Ghigo, M. Serio, A. Stella
    INFN/LNF, Frascati (Roma), Italy
  • A. Mostacci
    Rome University La Sapienza, Roma, Italy
  
  A methodology has been developed to perform electrical characterization of the stripline BPMs for the future Gamma Beam System of ELI Nuclear Physics facility in Romania. Several prototype units are extensively benchmarked and the results are presented in this paper. The BPM sensitivity function is determined using a uniquely designed motorized test bench with a stretched wire to measure the BPM response map. Here, the BPM feedthroughs are connected to Libera Brilliance electronics and the wire is fed by continuous wave signal, while the two software-controlled motors provide horizontal and vertical motion of the BPM around the wire. The electrical offset is obtained using S-parameter measurements with a Network Analyzer (via the "Lambertso" method) and is referenced to the mechanical offset.  
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TUPB051 Design of a New Super-heterodyne MicroTCA.4 BPM and LLRF Rear Transition Module (RTM) for the European Spallation 433
 
  • A. Young
    SLAC, Menlo Park, California, USA
  • H. Hassanzadegan
    ESS, Lund, Sweden
  
  Funding: Work supported by U.S. Department of Energy under Contract Numbers DE-AC02-06CH11357, DE-AC02-76SF00515, and CRADA 13-219C with the European Spallation Source AB
The 5MW European Spallation Source (ESS) is a long pulsed source based on a high power superconducting LINAC. In order to achieve this high level of performance, the beam position measurement system needs to measure the beam position, phase and intensity in all foreseen beam modes with a pulse rate of 14 Hz, duration of 2.86 ms and amplitude ranging form 5 mA to 62.5 mA. We have designed a general purpose Beam Position Monitor (BPM) front-end electronics that has a dynamic range of 70dB. The front-end uses the MicroTCA (Micro Telecommunication Computing Architecture) for physics platform that consists of a 16-bit 125 MSPS ADC module (SIS8300L/2 from Struck) that uses the Zone 3 A1.1 classification for the RTM. This paper will discuss the design of this new RTM that includes eight channels of super-heterodyne receivers, two channels of DC-coupled inputs to measure klystron voltage and current, one vector modulator that modulates the LLRF output. The RTM communicates with the AMC FPGA using a QSPI interface over the zone 3 connection. 		 
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TUPB054 Electromagnetic Field Pre-alignment of the Compact Linear Collider (CLIC) Accelerating Structure with help of Wakefield Monitor Signals 446
 
  • N. Galindo Munoz, N. Catalán Lasheras, M. Wendt, S. Zorzetti
    CERN, Geneva, Switzerland
  • V.E. Boria
    DCOM-iTEAM-UPV, Valencia, Spain
  • A. Faus-Golfe
    IFIC, Valencia, Spain
  
  Funding: The PACMAN project is funded by the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no. 606839
The CLIC project, currently under study at CERN is an electron-positron collider at 3 TeV centre-of-mass energy and luminosity of 2*1034 cm-2s−1. Achieving such luminosity requires a beam dimension of 1 nm in the vertical plane and high beam stability. The TD24 is a traveling wave structure operating at 12 GHz designed to reach 100 MV/m at constant gradient. It consists of two coupling cells and 24 disks. The RF is coupled from cell to cell though an iris of 5.5 mm. To minimize the occurrence of wake-fields and minimize the emittance growth Δεy below 5%, the pre-alignment precision of the electrical centre of the accelerating structure (AS) on its support has to be better than 7 μm. Following, the AS is actively aligned with beam using the wake-field monitor (WFM) signals, with a resolution of 3.5 μm. A test bench for laboratory measurements has been designed and exploits the asymmetry created by RF scattering parameters of an off-centre conductive wire, stretched to locate the electromagnetic centre of the AS. Simulations and preliminary measurement results are presented. 		 
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TUPB056 Transverse Rigid Dipole and Intra-Bunch Oscillation Detection Using the Transverse Feedback Beam Position Detection Scheme in SPS and LHC 456
 
  • W. Höfle, G. Kotzian, D. Valuch
    CERN, Geneva, Switzerland
  
  The LHC and SPS transverse dampers use beam position electronics with I,Q detection at 400 MHz and 200 MHz, of the sum and difference signals from a strip-line pick-up. Digitization is performed to give synchronous bunch-by-bunch data at the rate of 40 MHz corresponding to the bunch spacing of 25 ns. A performance in the um range is achieved with beams in LHC and has contributed to the high performance of the essential transverse feedback during the LHC run 1. In the present paper we review the systems deployed and their performance as well as the potential of the I,Q detection to also detect intra-bunch motion. The principle is illustrated using data from the LHC scrubbing runs in which intra-bunch motion is expected and has been observed due to electron cloud instabilities. The potential use of this signal to drive a transverse intra-bunch feedback system is outlined.  
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TUPB058 A New Orbit System for the CERN Antiproton Decelerator 465
 
  • R. Marco-Hernandez, M.E. Angoletta, M. Ludwig, J.C. Molendijk, F. Pedersen, R. Ruffieux, J. Sanchez-Quesada, L. Søby
    CERN, Geneva, Switzerland
  
  This contribution will describe the new orbit system foreseen for the Antiproton Decelerator (AD) located at CERN. The AD decelerates antiprotons from 3.57 GeV/c down to 100 MeV/c, with an intensity ranging from 1×107 to 5×107 particles. The orbit system developed is based on 34 horizontal and 29 vertical electrostatic beam position monitors (BPMs) fitted with existing low noise front-end amplifiers. After amplification, the BPM signals will be digitized and down-mixed to baseband, decimated and filtered before computation to extract the position. The digital acquisition part of the orbit measurement system is based on the VME Switched Serial (VXS) enhancement of the VME64x standard and includes VITA57 standard FPGA Mezzanine Cards (FMC). The system is foreseen to measure complete orbits every 2.5 ms with a resolution of 0.1 mm.  
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TUPB060 Development and Test of High Resolution Cavity BPMs for the CLIC Main Beam Linac 474
 
  • J.R. Towler, T. Lefèvre, M. Wendt
    CERN, Geneva, Switzerland
  • S.T. Boogert, A. Lyapin
    JAI, Egham, Surrey, United Kingdom
  • B.J. Fellenz
    Fermilab, Batavia, Illinois, USA
  
  The main beam of the Compact LInear Collider (CLIC) requires the beam trajectory to be measured with 50 nm spatial resolution. It also requires a time resolution capable of making position measurements of the head and tail of the 156 ns long CLIC bunch train, for use in dispersion free steering based on an energy chirp applied along the train. For this purpose, a stainless steel 15 GHz cavity BPM prototype has been manufactured, installed at the CLIC Test Facility (CTF3) and tested with beam. An improved design has been fabricated from copper. We discuss results from the two types of the prototype pickups, both from laboratory tests and from beam tests. We also cover the development of the new downconverter electronics.  
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TUPB062 Status of the PACMAN Project 483
 
  • H. Mainaud Durand, K. Artoos, M.C.L. Buzio, D. Caiazza, N. Catalán Lasheras, A. Cherif, I.P. Doytchinov, J.-F. Fuchs, A. Gaddi, N. Galindo Munoz, J. Gayde, M. Modena, P. Novotny, S. Russenschuck, C. Sanz, G. Severino, K.W. Solomon, D. Tshilumba, V. Vlachakis, M. Wendt, S. Zorzetti
    CERN, Geneva, Switzerland
  
  Funding: The PACMAN project is funded by the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no. 606839
PACMAN, a study on Particle Accelerator Components' Metrology and Alignment to the Nanometre scale, is an Innovative Doctoral Program, funded by the European Commission, hosted by CERN. The objective is to propose new methods allowing the determination of the reference axis of accelerator components with respect to external alignment targets. A test bench, using real components of the Compact Linear Collider (CLIC) study, will demonstrate the feasibility of the solutions developed with micrometric accuracy. The study concerns the methods developed using a stretched wire to determine the magnetic axis of small aperture magnets, the electrical centre of a 15 GHz RF-BPM or the electro-magnetic axis of an accelerating cavity. Solutions are also carried out to measure the position of the wire with respect to the external alignment targets, using a 3D Coordinate Measuring Machine or portable alternatives based on Frequency Scanning Interferometry or micro-triangulation. Other systems developed are also taken into account: a nano-positioning system to validate the nanometric resolution of the BPM and a dedicated seismic sensor to characterize the environment during the measurements. 		 
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TUPB063 Stretched-Wire Techniques and Measurements for the Alignment of a 15GHz RF-BPM for CLIC 487
 
  • S. Zorzetti, N. Galindo Munoz, M. Wendt
    CERN, Geneva, Switzerland
  • L. Fanucci
    Università di Pisa, Pisa, Italy
  
  Funding: The PACMAN project is funded by the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no. 606839
For the Compact LInear Collider (CLIC) project at CERN, maintaining low emittance beams, as they are transported along the two independent 10-20 km long main linacs, is crucial. The beam trajectory therefore has to be very well aligned to the magnetic centre of the quadrupole magnets. A series of microwave cavity beam position monitors (BPM) is foreseen to detect the position of the beam along the main linacs to precisely monitor the beam trajectory in the circular beam pipe of only 8 mm diameter. The PACMAN project aims to demonstrate the pre-alignment of the magnetic field of a main CLIC quadrupole with the electro-magnetic centre of a 15 GHz RF-BPM to the required sub-micron accuracy. This paper focuses on stretched-wire measurements of a CLIC Test Facility (CTF) cavity BPM, to locate its electrical centre. Details of two measurement methods are discussed: RF signal excitation of the wire and analysis of RF signal transfer through the slot-coupled waveguides of the cavity, using the stretched wire as a passive target. This contribution will present the theory behind these measurements, their electromagnetic analysis and first, preliminary experimental results. 		 
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TUPB064 Status of The European XFEL Transverse Intra Bunch Train Feedback System 492
 
  • B. Keil, R. Baldinger, R. Ditter, M. Gloor, W. Koprek, F. Marcellini, G. Marinkovic, M. Roggli, M. Rohrer, M. Stadler, D.M. Treyer
    PSI, Villigen PSI, Switzerland
  
  Funding: This work was partially funded by the Swiss State Secretariat for Education, Research and Innovation SERI
The European XFEL (E-XFEL) will have a transverse intra bunch train feedback system (IBFB) that is capable of correcting the beam position of individual bunches in the ~650us long bunch train, with a minimal bunch spacing of 222ns. The IBFB measures the beam positions with high-resolution cavity BPMs, and corrects the position of each bunch via stripline kicker magnets driven by class AB solid-state RF power amplifiers. The production of the IBFB BPM pickups is finished, and a pre-series version of the low-latency BPM electronics, including firmware and software, has been successfully tested with beam. After successful production and tests of prototypes, the series production of IBFB kicker magnets and RF power amplifiers is in progress. The IBFB feedback electronics hardware development is mainly finished, while firmware and software development is still in progress. This report summarizes the latest design status and test results of the different IBFB system components. 		 
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TUPB065 Status of The SwissFEL BPM System 497
 
  • B. Keil, R. Baldinger, R. Ditter, D. Engeler, W. Koprek, R. Kramert, A. Malatesta, F. Marcellini, G. Marinkovic, M. Roggli, M. Rohrer, M. Stadler
    PSI, Villigen PSI, Switzerland
  
  SwissFEL is a 5.8GeV free electron laser facility presently under construction at PSI. The electron beam position will be measured by three types of cavity beam position monitors. For the injector, linac and beam transfer lines, low-Q 3.3GHz cavity BPMs with 38mm and 16mm aperture (CBPM38 and CBPM16) will be used to measure the position and charge of two bunches with 28ns spacing individually. A fast kicker system distributes each bunch to a different undulator line, where 4.9GHz high-Q cavity BPMs with 8mm aperture (CBPM8) are used in the undulator intersections. The production of the CBPM38 pickups is finished, while the CBPM16 production is in progress. For CBPM8, a prototype pickup has been successfully tested, and a 2nd pre-series prototype with reduced dark-current sensitivity is currently in production. The development of the common 3.3GHz CBPM electronics for CBPM38 and CBPM16 is finished, while the CBPM8 electronics is currently in the prototyping phase. This paper gives an overview of the present pickup, electronics, firmware and software design and production status, including test results and methods to control and maintain the quality during series production.  
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TUPB066 Preliminary Test of the Bunch-by-Bunch Transverse Feedback System for TPS Storage Ring 502
 
  • Y.-S. Cheng, P.C. Chiu, K.T. Hsu, S.Y. Hsu, H.P. Hsueh, K.H. Hu, C.Y. Liao
    NSRRC, Hsinchu, Taiwan
  
  Commissioning of the Taiwan Photon Source (TPS) is in progress and divided into two phases. The storage ring equips with two five-cell PETRA RF cavities and without insertion devices installed for Phase-I commission to confirm correctness of everything, to do preliminary vacuum clearing, and wait available of cryogenic system available. After finished the Phase I commissioning in March, 2015, installation of two superconducting RF cavities and 10 sets of insertion devices are ongoing. The commissioning is planned to start around in August. There is a prototype vertical stripline kicker installed in 2014. One horizontal stripline kicker and two vertical stripline kickers were installed in May. Commercial available feedback processor was selected for the feedback system integration. Preliminary feedback loop closed have been tested during Phase-I beam commissioning in early 2015 with prototype vertical kicker. Beam commissioning with new kickers is scheduled when beam stored in Phase-II beam commissioning which will started soon. Final check before beam test is under way.  
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TUPB068 Commissioning of BPM System for the TPS Project 512
 
  • P.C. Chiu, Y.-S. Cheng, K.T. Hsu, K.H. Hu, C. H. Huang, C.H. Kuo, D. Lee
    NSRRC, Hsinchu, Taiwan
  
  Beam position monitor system for TPS (Taiwan Photon Source) project include several different kinds of button BPMs distributed at transfer line and booster synchrotron booster, and the storage ring. All BPM equip with commercial Libera single-pass BPM electronics and Libera Brilliance+ BPM electronics. Commissioning of the TPS accelerator system start in late 2014 for phase I commissioning until the first quarter of 2015. Phase II commissioning equip with SRF and insertion devices is schedule in the 3rd and 4th quarter of 2015. System integration, software supports, tools available for commissioning, functionality and performance of BPM system will be summary in this reports.  
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TUPB070 Beam Characterization Using Laser Self-Mixing 516
 
  • A.S. Alexandrova, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • A.S. Alexandrova, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  Funding: The European Union's Seventh Framework Programme under grant agreement no 289191; HGF and GSI under contract VH-NG-328 and STFC under the Cockcroft Institute Core Grant No.ST/G008248/1
Non-destructive diagnostics of particle beams is highly desirable for essentially any accelerator or storage ring. This concerns the characterization of the primary beam itself, but also for example of atom and molecular jets that are crossed with the primary beam as experimental targets or for diagnostics purposes. A laser-feedback interferometer based on the optical self-mixing effect provides a low-cost, robust, compact and non-invasive sensor for velocity, displacement and density measurements of various targets. This contribution presents results from theoretical and experimental studies into the factors influencing the performance and accuracy of this sensor. Parameters that have been assessed include the target velocity, the size of scattering particles, their density, type and scattering properties. 		 
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TUPB073 Characterising the Signal Processing System for Beam Position Monitors at the Front End Test Stand 526
 
  • G.E. Boorman, S.M. Gibson, N. Rajaeifar
    Royal Holloway, University of London, Surrey, United Kingdom
  • J.D. Gale
    University of Sussex, Brighton, United Kingdom
  • S. Jolly
    UCL, London, United Kingdom
  • S.R. Lawrie
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • A.P. Letchford
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  • J.K. Pozimski
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  
  A number of beam position monitors are being installed at the Front End Test Stand H− ion source at the Rutherford Appleton Laboratory, UK, as part of the 3 MeV medium energy beam transport. The FETS ion source delivers pulses up to 2 ms long at a rate up to 50 Hz and a maximum current of 60 mA, with a 324 MHz micro-bunch structure imposed by the frequency of the FETS RF acceleration cavity. The response of an in-house designed button BPM has been simulated and then characterised on a wire-based test-rig and the results are presented. The output from a custom algorithm running on a commercial PXI-based FPGA signal processing system is evaluated using test signals from both a function generator and the BPM in the test-rig, to verify the speed and precision of the processing algorithm. The processing system can determine the beam position in eight BPMs, with a precision of better than 20 microns, within one microsecond of the signal sampling being completed. Work is ongoing to reduce the processing time to below 300 ns.  
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TUPB080 Signal Processing Algorithm for Beam Position and Phase Monitors at LANSCE 540
 
  • R.C. McCrady, H.A. Watkins
    LANL, Los Alamos, New Mexico, USA
  
  Funding: This work is supported by the United States Department of Energy under contract DE-AC52-06NA2596.
The new beam position and phase monitors at LANSCE measure the phase of the beam relative to a reference signal from the master reference oscillator. Because of the various beam pulse formats used at LANSCE the algorithm needs to be flexible and to work well with short bursts of signals. We have developed an algorithm that provides phase resolution of better than 0.25 degrees with signal bursts one microsecond long, and also allows measurement of bursts as short as 100 nanoseconds. For beam position measurements flexibility took priority over precision; the processing scheme provides precision of less than 0.1 mm. In this paper we will present the principles of the algorithm and results of measurements. 		 
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TUPB086 Observation of Ion-induced Instabilities at NSLS2 Storage Ring 557
 
  • W.X. Cheng, Y. Li, B. Podobedov
    BNL, Upton, Long Island, New York, USA
  
  NSLS2 storage ring has been commissioned and is open for user operations. At relatively low beam current (~ 25mA) multi-bunch fills, ion-induced instabilities have been observed. For the present user operations, 150mA of total beam current is filled in ~1000 bunches, fast ion is the dominant instability at the NSLS2 storage ring. Although the ion-induced dipole motions can be suppressed using bunch by bunch (BxB) feedback system and it is expected to decrease in severity as the vacuum conditioning progresses further, a thorough understanding and characterization of this effect is still important, especially in preparation to the future 500mA operations. A number of ion instability related studies, mostly parasitic to other machine activities, have been carried out at various fill patterns and beam currents. Preliminary measurement results are reported in this paper.  
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WECLA04 Wideband Vertical Intra-Bunch Feedback at the SPS - Technology Development, Recent Accelerator Measurements and Next Steps 595
 
  • J.D. Fox, J.E. Dusatko, C.H. Rivetta, O. Turgut
    SLAC, Menlo Park, California, USA
  • H. Bartosik, W. Höfle, B. Salvant, U. Wehrle
    CERN, Geneva, Switzerland
  • S. De Santis
    LBNL, Berkeley, California, USA
  
  Funding: Work supported by the U.S. Department of Energy under contract # DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP).
A wideband vertical intra-bunch feedback system is in development at the CERN SPS for use to control potential Ecloud and TMCI instabilities. The work is motivated by planned intensity increases from the LIU and HL-LHC upgrade programs. System technical features include pickups, upgraded kickers and related RF power amplifiers, analog processing with 1 GHz bandwidth, with a with 4 GS/sec reconfigurable digital signal processing system. Recent results include driven beam experiments and beam simulation methods to verify the damping provided by the wideband system, and validate reduced MIMO models and model-based controllers. Noise effects and uncertainties in the model are evaluated via SPS measurements to predict the limits of control techniques applied to stabilize the intrabunch dynamics. We present data showing the excitation and damping of unstable modes. The plans for the next year, including experimental measurements, hardware upgrades and future control developments are described. 		 
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WEDLA02 High Frequency Electro-Optic Beam Position Monitors for Intra-Bunch Diagnostics at the LHC 606
TUPB072   use link to see paper's listing under its alternate paper code  
 
  • S.M. Gibson, A. Arteche, G.E. Boorman, A. Bosco
    Royal Holloway, University of London, Surrey, United Kingdom
  • P.Y. Darmedru, T. Lefèvre, T.E. Levens
    CERN, Geneva, Switzerland
  
  At the HL-LHC, proton bunches will be rotated by crab-cavities close to the interaction regions to maximize the luminosity. A method to rapidly monitor the transverse position of particles within each 1ns bunch is required. A novel, compact beam diagnostic to measure the bunch rotation is under development, based on electro-optic crystals, which have sufficient time resolution (<50ps) to monitor intra-bunch perturbations. The electro-optic beam position monitor uses two pairs of crystals, mounted on opposite sides of the beam pipe, whose birefringence is modified by the electric field of passing charged particle beam. The change of birefringence depends on the electric field which itself depends on the beam position, and is measured using polarized laser beams. The electro-optic response of the crystal to the passing bunch has been simulated for HL-LHC bunch scenarios. An electro-optical test stand including a high voltage modulator has been developed to characterize LiTaO3 and LiNiO3 crystals. Tests to validate the different optical configurations will be reviewed. The opto-mechanical design of an electro-optic prototype that will be installed in the CERN SPS will be presented.  
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THALA01 Beam Position Measurement System Design 618
 
  • H. Schmickler
    CERN, Geneva, Switzerland
  
  For newcomers, but also with interesting details for oldies, all components of a modern beam position measurement system are reviewed and explained. From specifications, sensor types, analogue and digital electronics over calibration methods the whole field will be covered. At the end some measurement examples will be shown and well as an outlook to upcoming research and developments.  
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THALA02 Characterization of NSLS2 Storage Ring Beam Orbit Stability 625
 
  • W.X. Cheng, K. Ha, J. Mead, B. Podobedov, O. Singh, Y. Tian, L. Yu
    BNL, Upton, Long Island, New York, USA
  
  Similar to other advanced third generation light sources, NSLS2 storage ring has stringent requirements on beam orbit stability. NSLS2 BPMs can be synchronously triggered to record turn by turn or fast acquisition 10kHz data. Spectrum of these data reveals various beam motion frequencies and it has been characterized at various machine conditions. Compared to the ground motion and utility system vibration spectra, beam motion introduced by the vibrations can be identified. An algorithm to locate possible noise sources from the measured spectrum has been developed. Preliminary results of locating orbit sources will be discussed in this paper as well.  
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