Z. Martí, G. Benedetti, U. Iriso, E. Morales
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
A. Franchi
ESRF, Grenoble, France
Fast beam-based alignment (BBA) of BPMs and quadrupole magnets was evolved and demonstrated at ALBA*. A conventional BBA method makes a local bump, change quadrupole strength, and measure COD by the quadrupole, which is very time-consuming. However, the fast BBA using AC excitations of corrector magnets can quickly measure the displacement between a BPM and a quadrupole. In the case of ALBA, the BBA duration was reduced from 5 hours to 10 minutes. The accuracy was the same as the conventional BBA (~10 um). This fast BBA method will help the alignment of BPMs in 3rd and 4th generation light sources. *: Z. Marti et al., Phys. Rev. Accel. Beams 23, 012802 (2020)
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An Experimental Comparison of Single Crystal CVD Diamond and 4H-SiC Synchrotron X-Ray Beam Diagnostics
21
C.E. Houghton, C. Bloomer, L. Bobb
DLS, Harwell, United Kingdom
As synchrotron beamlines increasingly use micro-focus techniques with detectors sampling at kHz rates, the need for real-time monitoring of the beam position at similar bandwidths is vital. Commercially available single-crystal CVD diamond X-ray diagnostics are well established as excellent non-destructive monitors for synchrotron X-ray beamlines. Silicon carbide (4H-SiC) X-ray beam position monitors (XBPMs) are a recent development with the potential to provide the same benefits as their diamond counterparts with larger usable apertures and lower cost. At Diamond Light Source a comparison between single-crystal CVD diamond and 4H-SiC XBPMs has been carried out. The sc-diamond and 4H-SiC beam position monitors are mounted in-line along the beam path, so that synchronous kHz measurements of the synchrotron X-ray beam motion can be measured. Several tests of the two position monitors performance are presented: comparing kHz beam position measurements from the detectors, temporal response, and signal uniformity across the face of the detectors. Each test is performed with varying bias voltages applied to the detectors. A discussion of the benefits and limitations of 4H-SiC and diamond detectors is included.
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BPM System Development and Applications in Commission of SXFEL-UF
B. Gao
SARI-CAS, Pudong, Shanghai, People’s Republic of China
J. Chen, Y.B. Leng
SSRF, Shanghai, People’s Republic of China
SXFEL is a soft X-ray free electron laser user facility that is current being commissioned in Shanghai. It is based on a 1.5 GeV normal conducting high gradient C-band (linear accelerator) LINAC and contains two FEL beamline, a seeded FEL beamline and a SASE beamline, and five experimental stations. The performance of X-ray FEL depends strongly on the quality of the electron beam and single shot stability. We have developed a BPM system including SBPM and CBPM. The resolution of SBPM is better than 4μmeters, and the resolution of CBPM is better than 176 nm. Because of its excellent position resolution, it plays an important role in the SASE beamline commissioning. The beam adjusters rely on this system to find and maintain an ideal track, and complete the debugging of the SBP beamline within 21 days. This paper presents the system design, methods used to determine the resolution, the performance, and the applications of those BPMs.
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Beam Position Monitor for MYRRHA 17-100MeV Section
40
M. Ben Abdillah, F. Fournier
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
MYRRHA (Multi-Purpose Hybrid Research Reactor for High-Tech Applications) aims to demonstrate the feasibility of high-level nuclear waste transmutation at industrial scale. MYRRHA Facility aims to accelerate 4 mA proton beam up to 600 MeV. The accurate tuning of LINAC is essential for the operation of MYRRHA and requires measurement of the beam transverse position and shape, the phase of the beam with respect to the radiofrequency voltage with the help of Beam Position Monitor (BPM) system. MINERVA is the first phase of MYRRHA. It includes several sections allowing beam acceleration up to 100 MeV. A BPM prototype was realized for the single spoke section (17 MeV-100 MeV). This paper addresses the design, realization, and calibration of this BPMs and its associated electronics. The characterization of the beam shape is performed by means of a test bench allowing a position mapping with a resolution of 0.02 mm.
Design of a Cavity Beam Position Monitor for the FLASH 2020+ Undulator Intersection Project at DESY
44
D. Lipka
DESY, Hamburg, Germany
The FLASH 1 beamline at DESY will be upgraded from fixed to variable gap undulators in the next years. For this the vacuum beamline has to be adapted. This reduces the inner diameter compared to the existing chamber. The vacuum components should fit to the new dimension to minimize transitions and therefore reduce wakefields which could interact with the electron beam and disturb the SASE effect. The electron beam position in the intersection of the undulators should be detected with a high resolution and a large charge dynamic range. Cavity BPMs are known to fulfill these requirements. The existing design with 10 mm inner diameter for the Eu-XFEL is reduced to 6 mm. Additional improvements are: widening of the dipole resonator waveguide to adapt to the dipole mode and antenna transmission. The resonator frequency of 3.3 GHz and loaded quality factor of 70 are maintained to use electronic synergies to other projects. The design considerations and simulation results of the cavity BPM will be presented.
Research on the Optimal Amplitude Extraction Algorithm for Cavity BPM
48
J. Chen, Y.B. Leng, T. Wu, Y.M. Zhou
SSRF, Shanghai, People’s Republic of China
S.S. Cao, B. Gao
SARI-CAS, Pudong, Shanghai, People’s Republic of China
The wake field of different modes of cavity BPM carries different bunch information, the amplitude and phase of the signals of different modes can be extracted through the signal processing method to obtain the characteristic parameters of the source bunch. In the application of bunch charge and position measurement, the accurate amplitude extraction method for cavity BPM signal is the primary issue to be considered when designing the data acquisition and processing system. In this paper, through theoretical analysis and numerical simulation, it is proved that the optimal algorithm of amplitude extraction for CBPM exists, and the dependence between the data processing window size and the decay time of the cavity BPM under the optimal design is given. In addition, the relationship between the optimized amplitude extraction uncertainty and the noise-to-signal ratio, sampling rate of data acquisition and processing system, and the decay time of the cavity BPM is also proposed, which can also provide clear guidance for the design and optimization of the CBPM system.
Observation of Wakefield Effects with Wideband Feedthrough-BPM at the Positron Capture Section of the SuperKEKB Injector Linac
52
M.A. Rehman, T. Suwada
KEK, Ibaraki, Japan
At the SuperKEKB injector linac, positrons are generated by striking electron beam at tungsten target. The secondary electrons are also produced during positron creation and accelerated in the positron capture section. A new wideband feedthrough-beam position monitor (BPM) system was developed for synchronous detection of secondary produced e- and e+ beams with temporal separation of about 180 ps. When e+/e− bunches pass through the accelerating structure or vacuum duct of different radius, they generate wakefields. These wakefields can be directly observed with the feedthrough-BPM. A simulation study has also been carried to validate the observed wakefield effects with the feedthrough-BPM. The effects of wakefields on beam parameters will be reported in this paper.
S.S. Cao
SARI-CAS, Pudong, Shanghai, People’s Republic of China
R. Jiang, Y.B. Leng, R.X. Yuan
SSRF, Shanghai, People’s Republic of China
SHINE is a newly proposed high-repetition-rate X-ray FEL facility and will be used to generate brilliant X-rays between 0.4 and 0.25 keV. To guarantee the high performance of FEL light pulses, it put a strict requirement on the monitoring of electron bunch trajectory. The position resolution of each bunch at the undulator section is required to be better than 200 nm at a bunch charge of 100 pC. The cavity beam position monitor (CBPM) is widely used in FEL facilities for its unique high resolution and high sensitivity. The output signals of an ideal pillbox cavity are proportional to the resonant frequency. Compared with the C-band cavity, the X-band cavity is expected to have a higher signal-to-noise ratio which is especially helpful at low bunch charge. Therefore, an X-band CBPM prototype is developed for SHINE. This paper will focus on the difficulties encountered during the design and production process and the solutions.
Precise Single Bunch Measurements Using Fast RF Switches
63
W.X. Cheng, A.R. Brill
ANL, Lemont, Illinois, USA
Funding:Work supported by DOE contract No: DE-AC02-06CH11357 To measure the swap-out injection/extraction bunches of the Advanced Photon Source Upgrade (APS-U) storage ring, single-pass Beam Position Monitor (BPM) electronics will be installed in the first sectors after the injection with fast RF switches. The fast RF switch will select a bunch signal to be processed by the single pass BPM electronics, and have the remaining bunches processed by the regular BPM electronics. In addition to measuring the swap-out bunch during injection, the setup will be able to carry out various other measurements of any selected single bunch (or bunches). This paper presents the performance of the fast RF switches and related electronics.
J.W. Kwon, Y.S. Chung, G.D. Kim, H.J. Woo
IBS, Daejeon, Republic of Korea
E.H. Lim
Korea University Sejong Campus, Sejong, Republic of Korea
RAON (Rare isotope accelerator complex for On-line experiments) is accelerator to accelerate heavy ion such as uranium, oxygen, and proton. At P2DT(Post to Driver linac Transport line) section where is located between SCL3 and SCL2, particle beam would be higher charge state by stripper. In bending area in P2DT, BPM(Beam Position Monitor) should accept the beam that has large size (~10 cm) horizontally. Required BPM transverse position resolution is 150 um. We simulated Large type BPM with CST particle studio. Fabricated LBPM was tested on the developed wire test bench that could move BPM for width of ±80 mm, height of ±40 mm with manual steering knob.
G. Brajnik, R. De Monte
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
M. Cargnelutti, P. Leban, P. Paglovec, B. Repič
I-Tech, Solkan, Slovenia
In the last years, there has been a growing interest in using the pilot-tone technique for long-term stabilization of electron beam position monitors in synchrotrons. At Elettra, after an internal development, the effectiveness of this approach was proven with tests in the laboratory and on the storage ring. The pilot-tone scheme will be adopted for the eBPMs that will equip Elettra 2.0, the low-emittance upgrade of the present machine. In order to support the development, industrialisation and production of the overall system, a partnership with Instrumentation Technologies has been signed. With the extensive experience with the Libera instruments, the company will be engaged in improving the BPM system developed by Elettra and getting it ready for serial production. This paper presents the current status of the BPM system, with an emphasis on the efforts done to improve the key performance of the system and to address its weaknesses (e.g. enhancing single bunch response and low currents sensitivity) within the industrialisation process, with the goal to get to a reliable system, easy to maintain and that meets the multiple project requirements for the new storage ring, the booster, the pre-injector and the transfer lines.
Beam Position Detection of a Short Electron Bunch in Presence of a Longer and More Intense Proton Bunch for the AWAKE Experiment
75
E. Senes, R. Corsini, W. Farabolini, A. Gilardi, M. Krupa, T. Lefèvre, S. Mazzoni, M. Wendt
CERN, Geneva, Switzerland
P. Burrows, C. Pakuza
JAI, Oxford, United Kingdom
P. Burrows, C. Pakuza
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
W. Farabolini
CEA-DRF-IRFU, France
The AWAKE experiment studies the acceleration of electrons to multi-GeV levels driven by the plasma wakefield generated by an ultra-relativistic and high intensity proton bunch. The proton beam, being considerably more intense than the co-propagating electron bunch, perturbs the measurement of the electron beam position achieved via standard techniques. This contribution shows that the electrons position monitoring is possible by frequency discrimination, exploiting the large bunch length difference between the electron and proton beams. Simulations and a beam measurement hint, the measurement has to be carried out in a frequency regime of a few tens of GHz, which is far beyond the spectrum produced by the 1ns long (4 σ Gaussian) proton bunch. As operating a conventional Beam Position Monitor (BPM) in this frequency range is problematic, an innovative approach based on the emission of coherent Cherenkov Diffraction Radiation (ChDR) in dielectrics is being studied. After describing the monitor concept and design, we will report about the results achieved with a prototype system at the CERN electron facility CLEAR.
Development of a Pass-Through Diagnostic for Next-Generation XFELs Using Diamond Sensors
80
I. Silva Torrecilla, B.T. Jacobson, J.P. MacArthur, D. Zhu
SLAC, Menlo Park, California, USA
J. Bohon, D. Kim, J. Smedley
LANL, Los Alamos, New Mexico, USA
E. Gonzalez, S. Kachiguine, F. Martinez-Mckinney, S.M. Mazza, M. Nizam, R. Padilla, E.K. Potter, E. Ryan, B.A. Schumm, M. Tarka, M. Wilder
SCIPP, Santa Cruz, California, USA
C.T. Harris
Sandia National Laboratories, Albuquerque, New Mexico, USA
N.P. Norvell
UCSC, Santa Cruz, California, USA
X-ray FELs deliver rapid pulses on the femtoseconds scale, and high peak intensities that fluctuate strongly on a pulse-to-pulse basis. The fast drift velocity, and high radiation tolerance properties of CVD (chemical vapor deposition) diamonds, make these crystals a good candi-date material for developing a multi-hundred MHz pass-through diagnostic for the next generation of XFELs. Commercially available diamond sensors work as posi-tion-sensitive pass-through diagnostics for nJ-level pulses from synchrotrons. Supported by the University of Cali-fornia and the SLAC National Laboratory, a collaboration of UC campuses and National Laboratories have devel-oped a new approach to the readout of diamond diagnostic sensors designed to facilitate operation for FEL-relevant uJ and mJ pulses. Single-crystal diamond detectors have been tested on the XPP end station of the Linac Coherent Light Source beam at SLAC. We present results on the linearity and charge collection characteristics as a function of the density of deposited charge.
Beam Position Monitor Calibration by Rapid Channel Switching
84
R.L. Hulsart, R.J. Michnoff, S. Seletskiy, P. Thieberger
BNL, Upton, New York, USA
One of the requirements for low-energy RHIC electron cooling (LEReC) is a small relative angle between the ion and electron beams as they co-propagate. In order to minimize relative electron-ion trajectories angle, BPM measurements of both beams must be very accurate. Achieving this requires good electronic calibration of the associated cables and RF components, due to their inherent imperfections. Unfortunately, these are typically frequency dependent, especially in the RF filter and amplifier stages. The spectral content of the ion vs. electron bunch signals varies significantly, presenting a calibration challenge, even when using the same sampling channels and electronics to measure both beams. A scheme of rapidly swapping the BPM signals from the pickup electrodes between the two signal cables (and sampling channels), using switches installed near the BPM was implemented to combat these calibration is-sues. Bias in each signal path appears as an offset which has an equal and opposite component when the cables are reversed. Taking the average of the two measurements with the channels in normal and reverse positions reduces this offset error. Successful transverse cooling of the RHIC ion beam has been verified after using this switching technique to provide continuous calibration of the BPM electronics [1]. Details of the processing hard-ware and switch control methodology to achieve this result will be discussed.
Research on Resolution of Orbit Based on Clustering Analysis and BP Neural Network in SSRF
88
R. Jiang, Y.B. Leng, N. Zhang
SSRF, Shanghai, People’s Republic of China
Y.M. Deng
SINAP, Shanghai, People’s Republic of China
Keeping the beam current’s normal motion is an important mission for Shanghai Synchrotron Radiation Facility (SSRF). So the Orbit (rms)x/y is an main parameter for SSRF’s running. However, the orbital resolution has been constrained by the accuracy of acquired data. To eliminate BPM’s failure causing the inaccurate orbital resolution, the work based on clustering analysis and BP neural network to removed the abnormal BPM and recalculate the resolution of orbit. Data came from the machine research. The analysis results showed that the rms value of orbit is 100.75±6.87 um (x direction) and 14.9±0.6 um (y direction) using all BPM’s data but the recalculate value is 98.03±6 um (x direction) and 2.6±0.4 um (y direction) when eliminate the data of faulty BPM. The analysis result indicated that the method can optimize the resolution of orbit and next work is further to evaluate the orbital resolution with more operation data.
Signal Analysis and Detection for the BPMs of the LHC Hollow Electron Lens
91
G. Bantemits, M. Gąsior, A. Rossi, M. Wendt
CERN, Geneva 23, Switzerland
The Large Hadron Collider (LHC) at CERN will be equipped with two hollow electron lenses (HEL) for the high luminosity upgrade, which allow for scraping of the LHC proton or ion beams transverse tails by overlapping a coaxial hollow electron beam over a 3 m length. A precise alignment of the two beams is essential for the HEL functionality, the bunched LHC hadron beam of up to 7 TeV beam energy, and the non-relativistic, DC-like electron hollow beam of 10 keV energy. The absolute and relative transverse positions of both beams will be monitored by two stripline beam position monitors (BPM), located in the HEL, and the pickup signal processed by a narrowband signal detection system. This paper summarizes the analysis of the expected proton and electron beam signals, including laboratory measurements, with aim of a narrowband diode-detection read-out electronics as BPM signal processor.
Commissioning of ALPS, the New Beam Position Monitor System of CERN’s Super Proton Synchrotron
96
A. Boccardi, J. Albertone, M.B.M. Barros Marin, T.B. Bogey, V. Kain, K.S.B. Li, P.A. Malinowska, A. Topaloudis, M. Wendt
CERN, Geneva 23, Switzerland
The Super Proton Synchrotron (SPS) is both, the final machine in the pre-accelerator chain of the Large Hadron Collider (LHC) at CERN, and a machine providing several experiments with proton and ion beams. In the framework of CERN’s LHC Injectors Upgrade (LIU) project, aimed at improving the performances of the pre-accelerators in view of the high-luminosity upgrade of the LHC, the Beam Position Monitor (BPM) system of the SPS was redesigned during Run 2 of the LHC and deployed during the subsequent Long Shutdown 2 (LS2). This new system is called ALPS (A Logarithmic Position System) and acquires the signals from some 240 BPMs. It is designed to improve the system’s reliability and reduce the required maintenance with respect to its predecessor. During the restart of the SPS in 2021, the BPM system was a key element of the fast recommissioning of the machine, proving the validity of the chosen design approach and pre-beam commissioning strategy. This paper aims to illustrate the design choices made for ALPS, the strategy for commissioning it with beam in parallel with the machine restart, the commissioning procedure and the results obtained.
Signal Processing Architecture for the HL-LHC Interaction Region BPMs
100
D.R. Bett
JAI, Oxford, United Kingdom
A. Boccardi, I. Degl’Innocenti, M. Krupa
CERN, Geneva, Switzerland
In the HL-LHC era, the Interaction Regions around the ATLAS and CMS experiments will be equipped with 24 new Beam Position Monitors (BPM) measuring both counter-propagating beams in a common vacuum chamber. Numerical simulations proved that, despite using new high-directivity stripline BPMs, the required measurement accuracy cannot be guaranteed without bunch-by-bunch disentanglement of the signals induced by both beams. This contribution presents the proposed signal processing architecture, based on direct digitisation of RF waveforms, which optimises the necessary computing resources without a significant reduction of the measurement accuracy. To minimise the number of operations performed on a bunch-by-bunch basis in the FPGA, some of the processing takes place in the CPU using averaged data.
Harmonic Based Beam Position Measurements on Debunched Beams
104
M. Bozzolan
CERN, Geneva, Switzerland
In some accelerator environments, e.g. in linear accelerator (LINAC), the beam position is measured with a BPM operating at one particular strong harmonic component present in the beam signal. This approach has limitations once the beam gets debunched and the harmonic components drops. Nevertheless, from a signal processing point of view the signal-to-noise ratio can be still acceptable with highly debunched beams, leading, in principle, to a reasonable, even if degraded, position measurement. A simplified beam transport model developed for the CERN BI transfer line between LINAC4 and the PS Booster demonstrates, that in some case, the harmonic component cannot be used anymore for position measurement despite the fact it is still significative in amplitude.
Performance of BPM Readout Electronic Based on Pilot-Tone Generator and a Modified Libera Spark at ALBA
108
L. Torino, U. Iriso
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
As many synchrotron radiation sources, ALBA is also going through an upgrade project. At the same time, the world of BPM electronic is evolving fast to keep up with the stringent requirement of new facilities. In order to follow the situation closely and develop know-how for the future, we decided to install and test in our storage ring a BPM readout system composed by a Pilot-Tone generator (developed by Elettra) and a modified Libera Spark (by Instrumentation Technologies). We compare position measurement results and stability with the ones obtained by our standard Libera Brilliance and a Libera Brilliance+ electronics.
J. Ko, T. Ha, G. Hahn, D. Kim, S. Shin
PAL, Pohang, Republic of Korea
All 18 photon beam position monitors (PBPM) installed on the PLS-II are tungsten blade types. The elliptical polarized undulator (EPU) has the characteristic that the spatial profile of the beam varies depending on the polarization mode. This relates to the thermal load of the blade and changes in the blade material at fixed blade gaps are inevitable. In this paper, we analyze power density and flux density according to EPU mode and describe the process of installing PBPM with CVD-diamond blades on the PLS-II beamline for the first time.
Experimental Test of 8-Channel-Stripline BPM for Measuring the Momentum Spread of the Electron Beam at Injector Test Facility of Pohang Accelerator Laboratory
115
C.K. Sung, M. Chung, S.Y. Kim, B.K. Shin
UNIST, Ulsan, Republic of Korea
C. Kim, I.H. Nam
PAL, Pohang, Republic of Korea
A stripline beam position monitor has been developed with 8 feedthroughs in order to non-destructively measure the momentum spread of an beam. The beam momentum spread causes the variation of transverse beam width at a dispersive section and can be detected by the multipole moment based analysis of the beam-induced electromagnetic field. The feasibility of such a device has been tested with electron beam generated in the beamline of Injector Test Facility (ITF) at Pohang Accelerator Laboratory (PAL). The result of beam test will be presented and the future plan for an application to bunch compressors at X-ray Free Electron Laser (XFEL) of PAL will be followed.
Design and Optimisation of Beam Position Monitor for SPS-II Storage Ring
118
S. Naeosuphap
Synchrotron Light Research Institute (SLRI), Muang District, Thailand
P. Sudmuang
SLRI, Nakhon Ratchasima, Thailand
The Beam Position Monitors (BPMs) for the new Thailand synchrotron light source, Siam Photon Source II (SPS-II), has been designed utilizing as the essential tool for diagnosing the position of the beam in the storage ring. Its design with four-button type BPM has been optimized to obtain the high precision of position data in normal closed orbit and feedback mode as well as turn by turn information. We calculate feedthroughs capacitance, sensitivities, induced power on a 50 Ω load, and intrinsic resolution by using Matlab GUI developed by ALBA, to find the appropriate position, thickness, and gap of the BPM button. Extensive simulation with the electromagnetic simulation tool CST Particle Studio was also performed to investigate the dependence of the induced BPM signal, wakefield, Time Domain Reflectometry (TDR), and power loss on different BPM geometry.
Tests of the New BPM Long Term Drift Stabilization Scheme Based on External Crossbar Switching at PETRA III
123
G. Kube, F. Schmidt-Föhre, K. Wittenburg
DESY, Hamburg, Germany
A. Bardorfer, L. Bogataj, M. Cargnelutti, P. Leban, P. Paglovec, B. Repič
I-Tech, Solkan, Slovenia
The PETRA IV project at DESY aims to upgrade the present synchrotron radiation source PETRA III at DESY into an ultralow-emittance source which will be diffraction limited up to X-rays of about 10 keV. Using a multi bend achromat lattice, the small PETRA beam emittance translates directly into much smaller beam sizes at the insertion device source points, thus imposing stringent requirements on machine stability. In order to measure beam positions and control orbit stability to the requisite level of accuracy, a high resolution BPM system will be installed which consists of about 700 individual monitors with the readout electronics based on MTCA.4 as technical platform. In order to fulfill the requested long-term drift requirement to be less than 1 micron over a period of seven days, due to the PETRA-specific machine geometry the BPM cable paths have to be stabilized in addition. To achieve this demand, the well proven concept of crossbar switching was extended such that the analogue switching part is separated from the read-out electronics and brought as close as possible to the BPM pickup. This contribution summarizes first proof-of-principle measurements which were performed in the lab and at PETRA III using a modified Libera Brilliance+ with external switching matrix. These measurements indicate that the concept of external switching works well and that the performance of this modified test setup fulfills the specifications.
M. El Ajjouri, F. Alves, A. Gamelin, N. Hubert
SOLEIL, Gif-sur-Yvette, France
Synchrotron SOLEIL is preparing a machine upgrade based on multibend achromat lattice with a drastically reduced horizontal electron beam emittance (<100 pmrad). Foreseen quadrupole and sextupole strengths will impose a small vacuum chamber diameter and the future Beam Position Monitors (BPM) will have a 16 mm inner diameter (circular shape). To minimize the BPM contribution to the longitudinal impedance, and induced heating on their mechanics, the feedthrough and button shapes must be optimized. This paper summarizes the systematic electromagnetic simulations that have been carried on in order to distinguish the effect of single dimension changes (such as button thickness and shape, ceramic thickness and diameter) on the amplitudes and frequency position of the resonances. It also introduces the preliminary BPM design for the SOLEIL upgrade project.
N. Eddy, J.S. Diamond, B.J. Fellenz, R.R. Santucci, A. Semenov, D. Slimmer, D.C. Voy
Fermilab, Batavia, Illinois, USA
Funding:Work supported by the Fermi National Accelerator Laboratory, managed and operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. A new BPM system was used for commissioning and operation of the PIP2 Injector Test Facility. The system of 13 warm and 12 cold BPMs was based upon custom 250 MS/s digitizers controlled and readout over gigabit ethernet by a single multi-core rackmount server running linux. The system provided positions, intensity, and phase for each bpm as a pulse average or pulse waveform from 10 us to 4 ms at a 20 Hz pulse repetition rate.
Performance of the SLAC-PAL-Vitzrotech X-band Cavity BPMs in the LCLS-II Undulator Beam Lines
136
C.D. Nantista, S.L. Hoobler, P. Krejcik, D.S. Martinez-Galarce, B.D. McKee, M. Rowen, A. Young
SLAC, Menlo Park, California, USA
C. Kim
PAL, Pohang, Republic of Korea
Funding:Work supported by US DOE Contract No. DE-AC02-76SF00515. The hard X-ray and soft X-Ray undulator beamlines of the LCLS-II X-ray FEL incorporate 65 X-band RF beam position monitors for accurate tracking of the electron beam trajectories and Beam-Based Alignment. For this crucial function, a design was jointly developed between PAL and SLAC, consisting of a monopole reference cavity and a dipole position cavity, with signals coupled out through coaxial vacuum feed-throughs. For the relatively large quantity needed, the production of completed units was contracted to the Korean company, Vitzrotech, who developed the manufacturing processes to successfully fabricate the needed quantity. Herein, an overview is given of the production experience, tuning, installation, and performance of these devices.
Construction of a new accelerator is always an opportunity to face challenges and make new developments. The BPM diagnostics installed in the SPIRAL2 linac and the associated instrumentation are part of these developments. BPM instrumentations are, of course, used to measure positions and phases of ion beams but also transverse shapes, called ellipticity, as well as the beam velocity. Specifications involve knowing and calculating the sensitivities in position and in ellipticity as a function of the beam velocities. These impose small amplitude differences between channels, which require precise calibration of electronics. This paper describes the modelling and analysis of the BPM behaviour according to the beam velocity, the technical solutions, modifications and improvements. An analysis of the results and evolutions in progress are also presented.
Comparison of Two Long Term Drift Stabilization Schemes for BPM Systems
145
F. Schmidt-Föhre, G. Kube, K. Wittenburg
DESY, Hamburg, Germany
For the planned upgrade of synchrotron radiation sources PETRA (called PETRA IV) at DESY a much higher beam brilliance is requested. In order to measure according beam positions and to control orbit stability to the corresponding level of accuracy, a future high-resolution BPM system has to deliver the necessary requirements on machine stability. This needs to enable long-term drift requirements of even less than 1 micron beam position deviation per week. Such a specification goal requires an additional long-term drift stabilization of the beam position monitor (BPM) readout scheme for PETRA IV, which will include a compensation of BPM cable parameter drifts. This paper discusses a comparison of two common compensation schemes using different signal conditioning features, typically needed at machine topologies with long BPM cable paths. Certain critical aspects of the different schemes are discussed in this report, while existing successful measurements are referred in some references.
