IPAC2019 - List of Keywords (synchrotron-radiation)

Paper	Title	Other Keywords	Page
MOPGW029	Preliminary Study of Bunch Compression in the Hefei Light Source	lattice, storage-ring, radiation, electron	151
	W. Li, Z.H. Bai, W. Li, J.G. Wang, D.R. Xu, Z. Zhao USTC/NSRL, Hefei, Anhui, People’s Republic of China
	Funding: This work was supported by the Fundamental Research Funds for the Central Universities (Grant No.WK2310000082 and WK2310000077), and the National Natural Science Foundation of China(GrantNo.11475167). Short electron bunch has interesting applications in the synchrotron radiation light sources, such as the production of powerful coherent THz radiation, time resolving spectrum analysis, etc. In this work, we are interested in acquiring the short bunch in the storage ring with a small circumference like Hefei Light Source. In this paper, we tried to approach the short bunch in two separate methods: by increasing the higher harmonic cavity voltage and by reducing the momentum compaction factor. The preliminary result and observations are shown and discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW029
About •	paper received ※ 16 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW048	Design Study of an Electron Storage Ring for the Future Plan of Hiroshima Synchrotron Radiation Center.	storage-ring, synchrotron, radiation, emittance	200
	S. Matsuba, M. Katoh, K.S. Shimada HSRC, Higashi-Hiroshima, Japan K. Harada KEK, Ibaraki, Japan K. Kawase QST, Tokai, Japan
	Hiroshima synchrotron radiation center equips a 700 MeV electron storage ring nicknamed HiSOR. It has been operated for more than 20 years. The emittance of HiSOR is 400 nm, which is larger by one or more orders of magnitude than typical modern synchrotron light sources. Therefore, as the future plan of the facility, a new low emittance storage ring is desired. Several designs have been examined. In the newest version, we have selected the lattice structure similar to ASTRID 2 compact light source in Aarhus University, Denmark. The design goal is the energy of around 500 MeV, the circumference shorter than 50 m and the emittance smaller than 10 nm with straight sections for undulators more than 4. In this conference, we report the latest result from the design study.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW048
About •	paper received ※ 01 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPGW051	Diffusion Map Analysis in High Energy Storage Ring Based e⁺/e⁻ Collider	dynamic-aperture, radiation, collider, synchrotron	203
	J. Wu, Q. Qin, Y. Zhang IHEP, Beijing, People’s Republic of China J. Wu, Y. Zhang University of Chinese Academy of Sciences, Beijing, People’s Republic of China
	Funding: Project 11775238 supported by NSFC In a very high energy e⁺/e⁻ storage ring collider, e.g. Circular Electron Positron Collider (CEPC), the dynamic aperture is limited by the strong synchrotron radiation especially in the vertical direction. Some tracking results also shows that the beam lifetime does not correspond well to the dynamic aperture. Here we develop a method called diffusion map analysis, aiming to describe the beam distribution diffusion in transverse amplitude space by tracking less turns. The diffusion may come from quantum fluctuation of SR, beamstrahlung effect and nonlinearity. Comparing cases with different configuration of sextupoles, the diffusion map analysis presents good consistency with beam lifetime that needs much more turns of tracking. Constraints based on the diffusion map is applied to our dynamic aperture optimization, which could help us achieve enough long beam lifetime.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW051
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPGW059	Dynamic Aperture Limitation in e⁺ e⁻ Colliders due to Synchrotron Radiation in Quadrupoles	quadrupole, radiation, synchrotron, betatron	221
	A.V. Bogomyagkov, S.A. Glukhov, E.B. Levichev, S.V. Sinyatkin BINP SB RAS, Novosibirsk, Russia
	In a lepton storage ring of very high energy (e.g. in the e⁺e^- Higgs factory) synchrotron radiation from quadrupoles constrains transverse dynamic aperture even in the absence of any magnetic nonlinearities. This was observed in tracking for LEP and the Future Circular e⁺e^- Collider (FCC-ee). Synchrotron radiation in the quadrupoles modulates the particle energy at the double betatron frequency. Energy modulation varies transverse focusing strength at the same frequency and creates a parametric resonance of the betatron oscillations with unusual properties. It occurs at arbitrary betatron frequency and the magnitude of the parameter modulation of the betatron oscillation depends on the oscillation amplitude. Equilibrium between the radiation damping and the resonant excitation gives the boundary of the stable motion. Here we continue comparison of tracking results with analytical calculations of the parametric resonance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW059
About •	paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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TUZZPLS3	New Method of Calculation of the Wake due to Radiation and Space Charge Forces in Relativistic Beams	radiation, wakefield, electron, space-charge	1223
	G. Stupakov SLAC, Menlo Park, California, USA
	Funding: This work was supported by the Department of Energy, Contract No. DE-AC02-76SF00515. Radiation reaction force in a relativistic beam, also known as a CSR wakefield, is often computed using a 1D model of a line charge beam. While this model can serve as a useful tool for a quick calculation, in some cases, it may not be sufficiently accurate. In particular, this model misses the so-called compression effects associated with the change of the electromagnetic energy when the beam is compressed longitudinally or transversely. The existing 3D simulation codes that take this effect into account are often slow and are not easy to use. In this work, we propose a new approach to the calculations of radiation and space charge longitudinal forces based on the use of the integrals for the retarded potentials. Our main result expresses the rate of change of particles energy through 2D (in a 2D model) or 3D integrals for a given orbit of the beam. It generalizes the 1D model and includes the transient effects of at the entrance and the exit from the magnet. For a given beam line with known magnetic lattice, and a known distribution function of the beam, the calculation reduces to taking 2D or 3D integrals along the orbit.
	Slides TUZZPLS3 [2.080 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZZPLS3
About •	paper received ※ 29 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPMP014	Digital Control System of High Precision Magnet Power Supply for SPring-8-II	controls, feedback, power-supply, FPGA	1259
	C. Kondo, K. Fukami, S. Takano, T. Watanabe Japan Synchrotron Radiation Research Institute (JASRI), RIKEN SPring-8 Center, Hyogo, Japan T. Fukui, H. Tanaka RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan S. Nakazawa SES, Hyogo-pref., Japan N. Nishimori QST, Tokai, Japan C. Saji JASRI/SPring-8, Hyogo-ken, Japan
	For the SPring-8 upgrade plan, SPring-8-II, a variety of magnet power supplies (PS) from 10 W to larger than 100 kW with a high current stability of about 10 ppm (pk-pk, typ.) are required. In order to develop the PSs within a given time and budget, we plan to use a common control system based on a digital control technology that can be adopted for the variety and the high precision PSs. The system consists of a high-precision analog-digital converter (ADC) circuit and a field programmable gate array (FPGA). Since the precision of the ADC circuit determines the current stability of the PS, we first developed the ADC circuit of high accuracy of less than 10 ppm (pk-pk). A proportional-integral (PI) control logic and a digital pulse width modulation (PWM) function was implemented in the FPGA firmware. These functions can be easily modified for each power supply by a desktop computer. We prototyped a DC power supply equipped with the newly developed digital feedback control system and confirmed that the current fluctuation was suppressed to less than 10 ppm (pk-pk). In the presentation, we will report the current status and future perspective of our power supply development including the evaluation results of the new circuits and the power supply we have developed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP014
About •	paper received ※ 16 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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TUPMP037	Recent Developments of Monte-Carlo Codes Molflow+ and Synrad+	simulation, vacuum, photon, synchrotron	1327
	R. Kersevan, M. Ady CERN, Geneva, Switzerland
	Molflow+ and Synrad+ are Monte Carlo simulation tools for ultra-high vacuum and synchrotron radiation, respectively. Over the years they have become a common tool for designing and analysing the vacuum system of particle accelerators. This contribution gives a short summary about new features added since IPAC-14. Some highlights: In traditional Monte Carlo simulations, one simulated ’virtual’ particle represents a given number of physical molecules or photons. This is a weakness where the pressure or flux of the simulated system spans across multiple orders of magnitude. Synrad now supports low flux mode, a weighed Monte Carlo technique where the represented number of photons is reduced at every reflection, providing significantly better statistics at low flux regions. As for Molflow+, angle maps allow recording the molecules, directional distribution at any point, and then desorb a reduced gas quantity according to the recording. In linear systems, this allows iterative simulations that have been proven to treat systems up to 7 orders of magnitude of pressure difference. Without the new technique the computing time would be prohibitively slow on desktop computers, which is what most users of the two codes use. Both codes now have a built-in geometry builder that allows creating simple models through a set of 3D operations, and modifying those imported from CAD tools. Molflow+ has recently become open source, and it has been made compatible with, and tested on different versions of Linux and macOS. Examples of application of Molflow+ to novel Beam Gas Curtain detector and the design of the FCC-ee vacuum system will be given, alongside with some benchmarking runs against data published in literature. M. Ady, R. Kersevan, "Introduction to the Latest Version of the Test-particle Monte Carlo Code Molflow+", Proc. IPAC’14, Dresden, Germany, June 2014, pp. 2348-2350.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP037
About •	paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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WEPGW016	Turn-by-Turn Horizontal Bunch Size and Energy Spread Studies at KARA	synchrotron, radiation, detector, storage-ring	2498
	B. Kehrer, M. Brosi, E. Bründermann, S. Funkner, A.-S. Müller, G. Niehues, M.M. Patil, M. Schuh, J.L. Steinmann KIT, Karlsruhe, Germany L. Rota SLAC, Menlo Park, California, USA
	Funding: This work is funded by the BMBF under contract number: 05K16VKA The energy spread is an important beam dynamics parameter. It can be derived from measurements of the horizontal bunch size. At the KIT storage ring KARA a fast-gated camera is routinely used for horizontal bunch size measurements with a single-turn resolution for a limited time span. To overcome the limits of the current camera setup in respect to resolution and time span, a high-speed line array with up to 10 Mfps, the KALYPSO system, is foreseen as a successor. The KALYPSO versions range from 256-pixel to 1024-pixel and allow unlimited turn-by-turn imaging of a single bunch at KARA. We successfully tested such a system at our visible light diagnostics port and present first results in this contribution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW016
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPGW049	Deep Learning Applied for Multi-Slit Imaging Based Beam Size Monitor	network, simulation, SRF, synchrotron	2587
	B. Gao, Y.B. Leng SSRF, Shanghai, People’s Republic of China X.Y. Xu SINAP, Shanghai, People’s Republic of China
	In order to satisfy the requirement of high speed measurement and improve the accuracy of BSM (beam size monitor), multi-slit imaging based BSM has been proposed by SSRF at 2017. However, it is very difficult to deconvolve the image and figure out the beam size, which requires dedicated algorithms to solve this issue. Deep learning is one of the most popular algorithms, which can learn to mimic any distribution of data. In the region of Beam instrumentation, they can be taught to deal with many difficult problem. In this paper, multi-layer neural network is used to process the images from the multi-slit imaging system. Training processes, struct of the neural networks and the result of the experiments will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW049
About •	paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEPGW099	Development of a Beam Halo Monitor	radiation, synchrotron, electron, optics	2721
	V.G. Dudnikov, R.P. Johnson, M. Popovic Muons, Inc, Illinois, USA M.A. Cummings Northern Illinois University, DeKalb, Illinois, USA R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA
	Our innovative approach is to design the Beam Halo Monitor, where beam induced synchrotron radiation will be used to monitor the beam Halo. This involves an original scheme of light collection using a coronograph for measuring beam halo.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW099
About •	paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEPTS051	Comparison of Electron Cloud Build-Up Simulations Against Heat Load Measurements for the LHC Arcs With Different Beam Configurations	electron, simulation, operation, radiation	3232
	G. Skripka, G. Iadarola, L. Mether, G. Rumolo, E.G.T. Wulff CERN, Meyrin, Switzerland P. Dijkstal PSI, Villigen PSI, Switzerland
	Electron cloud effects are among the main performance limitations for the operation of the Large Hadron Collider (LHC) with 25 ns bunch spacing. A large number of electrons impacting on the beam screens of the cold magnets induces significant heat load, reaching values close to the full cooling capacity available from the cryogenic system. Interestingly, it is observed that parts of the machine that are by design identical show very different heat loads. We used numerical simulations to investigate the possibility that these differences are induced by different surface properties, in particular maximum Secondary Electron Yield (SEY) for the different cryomagnets. Using the PyECLOUD code, the electron cloud build-up was simulated assuming different values of SEY in the LHC cold magnets. Comparing the measured heat loads to the simulation results for the 25 ns beams at 450 GeV we have identified the SEY values that match the observations in these conditions. These SEY values were found to be in good agreement with the heat loads measured with different beam configurations (changing the bunch pattern, the bunch intensity and the beam energy).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS051
About •	paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPTS044	Parameter Design of a Rotating Coil Measurement System for Quadrupoles	quadrupole, dipole, multipole, focusing	4207
	Y. Xie, W. Chen Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China H. Liang, B. Qin, J. Yang HUST, Wuhan, People’s Republic of China
	Funding: This work was supported by The National Key Research and Development Program of China; and by National Natural Science Foundation of China (11375068). HUST-PTF is a 5-year National Key Research and Development Program of China which is composed of cyclotron, beamline system, treatment chambers, etc. The beamline system connects the cyclotron and treatment chambers, provides proton beams in adequate size and shape and is crucial to the whole program. Vast dipoles and quadrupoles are employed in the beamline. Aimed at the quadrupoles used in the beamline, this article carried out the research on the high-precision rotating coil magnetic measurements for quadrupoles, including the quadrupole parameters, the principle and structure of the measuring system, measuring procedures and data processing method. Design of the rotating coils and analysis of the main errors are also contained.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS044
About •	paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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THPTS046	The Limited B-Field Integral of Superconducting Longitudinal Gradient Bend Magnet	simulation, emittance, storage-ring, radiation	4213
	C. Chen, L. Wang, H.R. Zhang, T. Zhang USTC/NSRL, Hefei, Anhui, People’s Republic of China
	The National Synchrotron Radiation Laboratory (NSRL) is planning a fourth generation diffraction-limited light source–Hefei Advanced Light Source (HALS), it is based on a seven-bend achromat lattice providing an ultralow natural emittance of 34 pm rad. The emittance can be even lower with the use of longitudinal gradient bends (LGBs) and anti-bends (ABs). The designed energy for HALS is 2.4 GeV, superconducting LGB might be employed instead of normal bending magnet since it can improve radiated beam critical energy to hard x-ray regions without using up any straight sections. To get a peak field about 6 T and small B-field profile full width half maximum, SLS-2 type LGB is considered. In this paper, the limited B-field integral (along the beam path) is trying to be find with some restrictions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS046
About •	paper received ※ 12 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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THPTS093	Synchrotron Radiation Heating of the Helical Superconducting Undulator	photon, vacuum, synchrotron, radiation	4328
	J.C. Dooling, R.J. Dejus, V. Sajaev ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02- 06CH11357. A helical superconducting undulator (HSCU) was installed in the Advanced Photon Source (APS) Storage Ring (SR) during the January 2018 maintenance period. Shortly after the reintroduction of beam into the SR in late January, higher than expected heating was observed in the cryogenic cooling system. Steering the electron beam orbit in the upstream dipole provided reduction of the amount of synchrotron radiation reaching into the HSCU and allowed the device to properly cool and operate. Modeling the HSCU geometry with MARS shows the importance of Compton Scattering in transferring synchrotron photons with energies in the range of 10-100 keV through the vacuum chamber into the HSCU magnet pole and winding regions. Simulations carried out using MARS with EGS5 enabled indicate a rapid increase in transfer efficiency from the chamber wall to the HSCU with photon energy. Realistic spectral distributions of synchrotron photons are employed as input to MARS for several bending magnet field strengths.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS093
About •	paper received ※ 12 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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FRXXPLS3	Application of a Phase Space Beam Position and Size Monitor for Synchrotron Radiation	electron, synchrotron, detector, radiation	4376
	N. Samadi University of Saskatchewan, Saskatoon, Canada L.D. Chapman, L.O. Dallin CLS, Saskatoon, Saskatchewan, Canada X. Shi ANL, Argonne, Illinois, USA
	We will report on a system (ps-BPM) that can measure the electron source vertical position and angular motion along with the vertical source size and angular size at a single location in a synchrotron bend magnet beamline. This system uses a combination of a monochromator and a filter with a K-edge to which the monochromator was tuned in energy. The vertical distribution of the beam with and without the filter was simultaneously visualized with an imaging detector. The small range of angles from the source onto the monochromator crystals creates an energy range that allows part of the beam to be below the K-edge and the other part above. Measurement of the beam vertical location without the absorber and edge vertical location with the absorber allowes measurement of the source position and angle. The beam width and edge width give information about the vertical electron source size and angular distribution. The ps-BPM measurements have been made where the electron beam size and angular distribution was adjusted using skew quads. The ps-BPM measurements correlate well with modeling of the ps-BPM system as well as conventional beam size measurements using a pinhole. A phase-space beam position monitor for synchrotron radiation. J Synchrotron Radiat, 2015. 22(4): p. 946-55.
	Slides FRXXPLS3 [4.593 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-FRXXPLS3
About •	paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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Paper

Title

Other Keywords

Page

MOPGW029

Preliminary Study of Bunch Compression in the Hefei Light Source

lattice, storage-ring, radiation, electron

151

W. Li, Z.H. Bai, W. Li, J.G. Wang, D.R. Xu, Z. Zhao
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: This work was supported by the Fundamental Research Funds for the Central Universities (Grant No.WK2310000082 and WK2310000077), and the National Natural Science Foundation of China(GrantNo.11475167).
Short electron bunch has interesting applications in the synchrotron radiation light sources, such as the production of powerful coherent THz radiation, time resolving spectrum analysis, etc. In this work, we are interested in acquiring the short bunch in the storage ring with a small circumference like Hefei Light Source. In this paper, we tried to approach the short bunch in two separate methods: by increasing the higher harmonic cavity voltage and by reducing the momentum compaction factor. The preliminary result and observations are shown and discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW029

About •

paper received ※ 16 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPGW048

Design Study of an Electron Storage Ring for the Future Plan of Hiroshima Synchrotron Radiation Center.

storage-ring, synchrotron, radiation, emittance

200

S. Matsuba, M. Katoh, K.S. Shimada
HSRC, Higashi-Hiroshima, Japan
K. Harada
KEK, Ibaraki, Japan
K. Kawase
QST, Tokai, Japan

Hiroshima synchrotron radiation center equips a 700 MeV electron storage ring nicknamed HiSOR. It has been operated for more than 20 years. The emittance of HiSOR is 400 nm, which is larger by one or more orders of magnitude than typical modern synchrotron light sources. Therefore, as the future plan of the facility, a new low emittance storage ring is desired. Several designs have been examined. In the newest version, we have selected the lattice structure similar to ASTRID 2 compact light source in Aarhus University, Denmark. The design goal is the energy of around 500 MeV, the circumference shorter than 50 m and the emittance smaller than 10 nm with straight sections for undulators more than 4. In this conference, we report the latest result from the design study.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW048

About •

paper received ※ 01 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPGW051

Diffusion Map Analysis in High Energy Storage Ring Based e⁺/e⁻ Collider

dynamic-aperture, radiation, collider, synchrotron

203

J. Wu, Q. Qin, Y. Zhang
IHEP, Beijing, People’s Republic of China
J. Wu, Y. Zhang
University of Chinese Academy of Sciences, Beijing, People’s Republic of China

Funding: Project 11775238 supported by NSFC
In a very high energy e⁺/e⁻ storage ring collider, e.g. Circular Electron Positron Collider (CEPC), the dynamic aperture is limited by the strong synchrotron radiation especially in the vertical direction. Some tracking results also shows that the beam lifetime does not correspond well to the dynamic aperture. Here we develop a method called diffusion map analysis, aiming to describe the beam distribution diffusion in transverse amplitude space by tracking less turns. The diffusion may come from quantum fluctuation of SR, beamstrahlung effect and nonlinearity. Comparing cases with different configuration of sextupoles, the diffusion map analysis presents good consistency with beam lifetime that needs much more turns of tracking. Constraints based on the diffusion map is applied to our dynamic aperture optimization, which could help us achieve enough long beam lifetime.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW051

About •

paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPGW059

Dynamic Aperture Limitation in e⁺ e⁻ Colliders due to Synchrotron Radiation in Quadrupoles

quadrupole, radiation, synchrotron, betatron

221

A.V. Bogomyagkov, S.A. Glukhov, E.B. Levichev, S.V. Sinyatkin
BINP SB RAS, Novosibirsk, Russia

In a lepton storage ring of very high energy (e.g. in the e⁺e^- Higgs factory) synchrotron radiation from quadrupoles constrains transverse dynamic aperture even in the absence of any magnetic nonlinearities. This was observed in tracking for LEP and the Future Circular e⁺e^- Collider (FCC-ee). Synchrotron radiation in the quadrupoles modulates the particle energy at the double betatron frequency. Energy modulation varies transverse focusing strength at the same frequency and creates a parametric resonance of the betatron oscillations with unusual properties. It occurs at arbitrary betatron frequency and the magnitude of the parameter modulation of the betatron oscillation depends on the oscillation amplitude. Equilibrium between the radiation damping and the resonant excitation gives the boundary of the stable motion. Here we continue comparison of tracking results with analytical calculations of the parametric resonance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW059

About •

paper received ※ 13 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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TUZZPLS3

New Method of Calculation of the Wake due to Radiation and Space Charge Forces in Relativistic Beams

radiation, wakefield, electron, space-charge

1223

G. Stupakov
SLAC, Menlo Park, California, USA

Funding: This work was supported by the Department of Energy, Contract No. DE-AC02-76SF00515.
Radiation reaction force in a relativistic beam, also known as a CSR wakefield, is often computed using a 1D model of a line charge beam. While this model can serve as a useful tool for a quick calculation, in some cases, it may not be sufficiently accurate. In particular, this model misses the so-called compression effects associated with the change of the electromagnetic energy when the beam is compressed longitudinally or transversely. The existing 3D simulation codes that take this effect into account are often slow and are not easy to use. In this work, we propose a new approach to the calculations of radiation and space charge longitudinal forces based on the use of the integrals for the retarded potentials. Our main result expresses the rate of change of particles energy through 2D (in a 2D model) or 3D integrals for a given orbit of the beam. It generalizes the 1D model and includes the transient effects of at the entrance and the exit from the magnet. For a given beam line with known magnetic lattice, and a known distribution function of the beam, the calculation reduces to taking 2D or 3D integrals along the orbit.

Slides TUZZPLS3 [2.080 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZZPLS3

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paper received ※ 29 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPMP014

Digital Control System of High Precision Magnet Power Supply for SPring-8-II

controls, feedback, power-supply, FPGA

1259

C. Kondo, K. Fukami, S. Takano, T. Watanabe
Japan Synchrotron Radiation Research Institute (JASRI), RIKEN SPring-8 Center, Hyogo, Japan
T. Fukui, H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
S. Nakazawa
SES, Hyogo-pref., Japan
N. Nishimori
QST, Tokai, Japan
C. Saji
JASRI/SPring-8, Hyogo-ken, Japan

For the SPring-8 upgrade plan, SPring-8-II, a variety of magnet power supplies (PS) from 10 W to larger than 100 kW with a high current stability of about 10 ppm (pk-pk, typ.) are required. In order to develop the PSs within a given time and budget, we plan to use a common control system based on a digital control technology that can be adopted for the variety and the high precision PSs. The system consists of a high-precision analog-digital converter (ADC) circuit and a field programmable gate array (FPGA). Since the precision of the ADC circuit determines the current stability of the PS, we first developed the ADC circuit of high accuracy of less than 10 ppm (pk-pk). A proportional-integral (PI) control logic and a digital pulse width modulation (PWM) function was implemented in the FPGA firmware. These functions can be easily modified for each power supply by a desktop computer. We prototyped a DC power supply equipped with the newly developed digital feedback control system and confirmed that the current fluctuation was suppressed to less than 10 ppm (pk-pk). In the presentation, we will report the current status and future perspective of our power supply development including the evaluation results of the new circuits and the power supply we have developed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP014

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paper received ※ 16 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPMP037

Recent Developments of Monte-Carlo Codes Molflow+ and Synrad+

simulation, vacuum, photon, synchrotron

1327

R. Kersevan, M. Ady
CERN, Geneva, Switzerland

Molflow+ and Synrad+ are Monte Carlo simulation tools for ultra-high vacuum and synchrotron radiation, respectively. Over the years they have become a common tool for designing and analysing the vacuum system of particle accelerators. This contribution gives a short summary about new features added since IPAC-14*. Some highlights: In traditional Monte Carlo simulations, one simulated ’virtual’ particle represents a given number of physical molecules or photons. This is a weakness where the pressure or flux of the simulated system spans across multiple orders of magnitude. Synrad now supports low flux mode, a weighed Monte Carlo technique where the represented number of photons is reduced at every reflection, providing significantly better statistics at low flux regions. As for Molflow+, angle maps allow recording the molecules, directional distribution at any point, and then desorb a reduced gas quantity according to the recording. In linear systems, this allows iterative simulations that have been proven to treat systems up to 7 orders of magnitude of pressure difference. Without the new technique the computing time would be prohibitively slow on desktop computers, which is what most users of the two codes use. Both codes now have a built-in geometry builder that allows creating simple models through a set of 3D operations, and modifying those imported from CAD tools. Molflow+ has recently become open source, and it has been made compatible with, and tested on different versions of Linux and macOS. Examples of application of Molflow+ to novel Beam Gas Curtain detector and the design of the FCC-ee vacuum system will be given, alongside with some benchmarking runs against data published in literature.
* M. Ady, R. Kersevan, "Introduction to the Latest Version of the Test-particle Monte Carlo Code Molflow+", Proc. IPAC’14, Dresden, Germany, June 2014, pp. 2348-2350.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP037

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPGW016

Turn-by-Turn Horizontal Bunch Size and Energy Spread Studies at KARA

synchrotron, radiation, detector, storage-ring

2498

B. Kehrer, M. Brosi, E. Bründermann, S. Funkner, A.-S. Müller, G. Niehues, M.M. Patil, M. Schuh, J.L. Steinmann
KIT, Karlsruhe, Germany
L. Rota
SLAC, Menlo Park, California, USA

Funding: This work is funded by the BMBF under contract number: 05K16VKA
The energy spread is an important beam dynamics parameter. It can be derived from measurements of the horizontal bunch size. At the KIT storage ring KARA a fast-gated camera is routinely used for horizontal bunch size measurements with a single-turn resolution for a limited time span. To overcome the limits of the current camera setup in respect to resolution and time span, a high-speed line array with up to 10 Mfps, the KALYPSO system, is foreseen as a successor. The KALYPSO versions range from 256-pixel to 1024-pixel and allow unlimited turn-by-turn imaging of a single bunch at KARA. We successfully tested such a system at our visible light diagnostics port and present first results in this contribution.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW016

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPGW049

Deep Learning Applied for Multi-Slit Imaging Based Beam Size Monitor

network, simulation, SRF, synchrotron

2587

B. Gao, Y.B. Leng
SSRF, Shanghai, People’s Republic of China
X.Y. Xu
SINAP, Shanghai, People’s Republic of China

In order to satisfy the requirement of high speed measurement and improve the accuracy of BSM (beam size monitor), multi-slit imaging based BSM has been proposed by SSRF at 2017. However, it is very difficult to deconvolve the image and figure out the beam size, which requires dedicated algorithms to solve this issue. Deep learning is one of the most popular algorithms, which can learn to mimic any distribution of data. In the region of Beam instrumentation, they can be taught to deal with many difficult problem. In this paper, multi-layer neural network is used to process the images from the multi-slit imaging system. Training processes, struct of the neural networks and the result of the experiments will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW049

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW099

Development of a Beam Halo Monitor

radiation, synchrotron, electron, optics

2721

V.G. Dudnikov, R.P. Johnson, M. Popovic
Muons, Inc, Illinois, USA
M.A. Cummings
Northern Illinois University, DeKalb, Illinois, USA
R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA

Our innovative approach is to design the Beam Halo Monitor, where beam induced synchrotron radiation will be used to monitor the beam Halo. This involves an original scheme of light collection using a coronograph for measuring beam halo.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW099

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPTS051

Comparison of Electron Cloud Build-Up Simulations Against Heat Load Measurements for the LHC Arcs With Different Beam Configurations

electron, simulation, operation, radiation

3232

G. Skripka, G. Iadarola, L. Mether, G. Rumolo, E.G.T. Wulff
CERN, Meyrin, Switzerland
P. Dijkstal
PSI, Villigen PSI, Switzerland

Electron cloud effects are among the main performance limitations for the operation of the Large Hadron Collider (LHC) with 25 ns bunch spacing. A large number of electrons impacting on the beam screens of the cold magnets induces significant heat load, reaching values close to the full cooling capacity available from the cryogenic system. Interestingly, it is observed that parts of the machine that are by design identical show very different heat loads. We used numerical simulations to investigate the possibility that these differences are induced by different surface properties, in particular maximum Secondary Electron Yield (SEY) for the different cryomagnets. Using the PyECLOUD code, the electron cloud build-up was simulated assuming different values of SEY in the LHC cold magnets. Comparing the measured heat loads to the simulation results for the 25 ns beams at 450 GeV we have identified the SEY values that match the observations in these conditions. These SEY values were found to be in good agreement with the heat loads measured with different beam configurations (changing the bunch pattern, the bunch intensity and the beam energy).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS051

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPTS044

Parameter Design of a Rotating Coil Measurement System for Quadrupoles

quadrupole, dipole, multipole, focusing

4207

Y. Xie, W. Chen
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China
H. Liang, B. Qin, J. Yang
HUST, Wuhan, People’s Republic of China

Funding: This work was supported by The National Key Research and Development Program of China; and by National Natural Science Foundation of China (11375068).
HUST-PTF is a 5-year National Key Research and Development Program of China which is composed of cyclotron, beamline system, treatment chambers, etc. The beamline system connects the cyclotron and treatment chambers, provides proton beams in adequate size and shape and is crucial to the whole program. Vast dipoles and quadrupoles are employed in the beamline. Aimed at the quadrupoles used in the beamline, this article carried out the research on the high-precision rotating coil magnetic measurements for quadrupoles, including the quadrupole parameters, the principle and structure of the measuring system, measuring procedures and data processing method. Design of the rotating coils and analysis of the main errors are also contained.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS044

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paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPTS046

The Limited B-Field Integral of Superconducting Longitudinal Gradient Bend Magnet

simulation, emittance, storage-ring, radiation

4213

C. Chen, L. Wang, H.R. Zhang, T. Zhang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

The National Synchrotron Radiation Laboratory (NSRL) is planning a fourth generation diffraction-limited light source–Hefei Advanced Light Source (HALS), it is based on a seven-bend achromat lattice providing an ultralow natural emittance of 34 pm rad. The emittance can be even lower with the use of longitudinal gradient bends (LGBs) and anti-bends (ABs). The designed energy for HALS is 2.4 GeV, superconducting LGB might be employed instead of normal bending magnet since it can improve radiated beam critical energy to hard x-ray regions without using up any straight sections. To get a peak field about 6 T and small B-field profile full width half maximum, SLS-2 type LGB is considered. In this paper, the limited B-field integral (along the beam path) is trying to be find with some restrictions.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS046

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paper received ※ 12 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPTS093

Synchrotron Radiation Heating of the Helical Superconducting Undulator

photon, vacuum, synchrotron, radiation

4328

J.C. Dooling, R.J. Dejus, V. Sajaev
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02- 06CH11357.
A helical superconducting undulator (HSCU) was installed in the Advanced Photon Source (APS) Storage Ring (SR) during the January 2018 maintenance period. Shortly after the reintroduction of beam into the SR in late January, higher than expected heating was observed in the cryogenic cooling system. Steering the electron beam orbit in the upstream dipole provided reduction of the amount of synchrotron radiation reaching into the HSCU and allowed the device to properly cool and operate. Modeling the HSCU geometry with MARS shows the importance of Compton Scattering in transferring synchrotron photons with energies in the range of 10-100 keV through the vacuum chamber into the HSCU magnet pole and winding regions. Simulations carried out using MARS with EGS5 enabled indicate a rapid increase in transfer efficiency from the chamber wall to the HSCU with photon energy. Realistic spectral distributions of synchrotron photons are employed as input to MARS for several bending magnet field strengths.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS093

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paper received ※ 12 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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FRXXPLS3

Application of a Phase Space Beam Position and Size Monitor for Synchrotron Radiation

electron, synchrotron, detector, radiation

4376

N. Samadi
University of Saskatchewan, Saskatoon, Canada
L.D. Chapman, L.O. Dallin
CLS, Saskatoon, Saskatchewan, Canada
X. Shi
ANL, Argonne, Illinois, USA

We will report on a system (ps-BPM) that can measure the electron source vertical position and angular motion along with the vertical source size and angular size at a single location in a synchrotron bend magnet beamline*. This system uses a combination of a monochromator and a filter with a K-edge to which the monochromator was tuned in energy. The vertical distribution of the beam with and without the filter was simultaneously visualized with an imaging detector. The small range of angles from the source onto the monochromator crystals creates an energy range that allows part of the beam to be below the K-edge and the other part above. Measurement of the beam vertical location without the absorber and edge vertical location with the absorber allowes measurement of the source position and angle. The beam width and edge width give information about the vertical electron source size and angular distribution. The ps-BPM measurements have been made where the electron beam size and angular distribution was adjusted using skew quads. The ps-BPM measurements correlate well with modeling of the ps-BPM system as well as conventional beam size measurements using a pinhole.
* A phase-space beam position monitor for synchrotron radiation. J Synchrotron Radiat, 2015. 22(4): p. 946-55.

Slides FRXXPLS3 [4.593 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-FRXXPLS3

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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