HB2018 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOA1PL01	Challenges in Understanding Space Charge Dynamics	space-charge, resonance, emittance, synchrotron	1
	H. Bartosik CERN, Geneva, Switzerland
	Space charge effects in high intensity and high brightness synchrotrons can lead to undesired beam emittance growth, beam halo formation and particle loss. A series of dedicated machine experiments has been performed over the past decade in order to study these effects in the particular regime of long-term beam storage (10⁵-10⁶ turns) as required for certain applications. This paper gives an overview of the present understanding of the underlying beam dynamics mechanisms. In particular it focuses on the space charge induced periodic resonance crossing, which has been identified as the main mechanism causing beam degradation in this regime. The challenges in further progressing with the understanding, the modelling and the mitigation of these space charge effects and the resulting beam degradation are discussed. Furthermore, an outlook for possible future directions of studies is presented.
	Slides MOA1PL01 [22.877 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-MOA1PL01
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MOP2WA03	Experiments and Theory on Beam Stabilization with Second-Order Chromaticity	impedance, damping, experiment, betatron	32
	M. Schenk, X. Buffat, L.R. Carver, K.S.B. Li, E. Métral CERN, Geneva, Switzerland A. Maillard ENS, Paris, France
	This study reports on an alternative method to generate transverse Landau damping to suppress coherent instabilities in circular accelerators. The incoherent betatron tune spread can be produced through detuning with longitudinal rather than transverse action. This approach is motivated by the high-brightness, low transverse emittance beams in future colliders where detuning with transverse amplitude will be less effective. Detuning with longitudinal action can be introduced with a radio frequency (rf) quadrupole, or similarly, using second-order chromaticity. The latter was enhanced in the Large Hadron Collider (LHC) at CERN and experimental results on single-bunch stabilization are briefly recapped. The observations are interpreted analytically by extending the Vlasov formalism to include nonlinear chromaticity. Finally, the newly developed theory is benchmarked against circulant matrix and particle tracking models.
	Slides MOP2WA03 [3.374 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-MOP2WA03
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MOP2WA05	Simulation and Measurement of the TMCI Threshold in the LHC	impedance, coupling, operation, synchrotron	43
	D. Amorim, S. A. Antipov, N. Biancacci, X. Buffat, L.R. Carver, E. Métral CERN, Geneva, Switzerland
	The transverse mode coupling instability occurs in individual bunches when two transverse oscillation modes couple at high intensity. Simulations predict an instability threshold in the LHC at a single bunch intensity of 3*10¹¹ protons. The TMCI threshold can be inferred by measuring the tune shift as a function of intensity. This measurement was performed in the LHC for different machine impedances and bunch intensities. The impedance was changed by varying the primary and secondary collimators gaps to increase their contribution to the resistive wall impedance. The experiment also allowed to assess the validity of the LHC impedance model in the single bunch case.
	Slides MOP2WA05 [4.729 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-MOP2WA05
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MOP1WB03	Experimental Study of Beam Dynamics in the PIP-II MEBT Prototype	rfq, cavity, optics, emittance	54
	A.V. Shemyakin, J.-P. Carneiro, B.M. Hanna, V.A. Lebedev, L.R. Prost, A. Saini, V.E. Scarpine Fermilab, Batavia, Illinois, USA C.J. Richard NSCL, East Lansing, Michigan, USA V.L. Sista BARC, Mumbai, India
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics The Proton Improvement Plan, Stage Two (PIP-II) is a program of upgrades proposed for the Fermilab injection complex, which central part is an 800-MeV, 2-mA CW SRF linac. A prototype of the PIP-II linac front end called PIP-II Injector Test (PIP2IT) is being built at Fermilab. As of now, a 15-mA DC, 30-keV H⁻ ion source, a 2 m-long Low Energy Beam Transport (LEBT), a 2.1-MeV CW RFQ, followed by a 10-m Medium Energy Beam Transport (MEBT) have been assembled and commissioned. The MEBT bunch-by-bunch chopping system and the requirement of a low uncontrolled beam loss put stringent limitations on the beam envelope and its variation. Measurements of transverse and longitudinal beam dynamics in the MEBT were performed in the range of 1-10 mA of the RFQ beam current. Almost all measurements are made with 10 μs beam pulses in order to avoid damage to the beam line. This report presents measurements of the transverse optics with differential trajectories, reconstruction of the beam envelope with scrapers and an Allison emittance scanner, as well as bunch length measurements with a Fast Faraday Cup.
	Slides MOP1WB03 [3.750 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-MOP1WB03
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MOP2WB01	60 mA Beam Study in J-PARC Linac	DTL, rfq, linac, lattice	60
	Y. Liu KEK/JAEA, Ibaraki-Ken, Japan A. Miura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan T. Miyao KEK, Ibaraki, Japan M. Otani, T. Shibata J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Upgrade of Linac peak current from 50 mA to 60 mA is one of the keys to the next power upgrade in J-PARC. Beam studies with 60 mA were carried out in July and December, 2017, for the challenging issues such as investigation of beam property from the ion source, halo behavior throughout the LEBT, RFQ and MEBT1, emittance/Twiss measurement at MEBT1, beam emittance control, etc. Expected/unexpected problems, intermediate results and preparation for the next trials were introduced in this paper.
	Slides MOP2WB01 [12.952 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-MOP2WB01
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MOP2WB02	Simulation and Measurement Campaigns for Characterization and Performance Improvement of the CERN Heavy Ion Linac3	linac, extraction, rfq, emittance	64
	G. Bellodi, S. Benedetti, D. Küchler, F.J.C. Wenander CERN, Geneva, Switzerland V. Toivanen GANIL, Caen, France
	In the framework of the LHC Injector Upgrade programme (LIU), several activities have been carried out to improve the GTS-LHC ion source and Linac3 performance (Linac3 providing the charged heavy ion beams for CERN exper-iments). A restudy of the beam dynamics and transport through the linac was initiated, through a campaign of systematic machine measurements and parallel beam simulations, generalising techniques developed for beam characterization during Linac4 commissioning. The work here presented will review the most relevant findings and lessons learnt in the process.
	Slides MOP2WB02 [17.512 MB]
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TUP2WE04	Design of the Target Dump Injection Segmented (TDIS) in the Framework of the High Luminosity Large Hadron Collider (HL-LHC) Project	injection, site, shielding, impedance	122
	L. Teofili, D. Carbajo Perez, I. Lamas Garcia, M. Migliorati, A. Perillo CERN, Geneva, Switzerland M. Migliorati INFN-Roma1, Rome, Italy M. Migliorati Sapienza University of Rome, Rome, Italy
	The High Luminosity Large Hadron Collider (HL-LHC) Project at CERN calls for increasing beam brightness and intensity. In this scenario most equipment has to be redesigned and rebuilt. In particular, beam intercepting devices (as dumps, collimators, absorbers and scrapers) have to withstand impact or scraping of the new intense HL-LHC beams without failures. Further, minimizing the electromagnetic beam-device interactions is also a key design driver since they can lead to beam instabilities and excessive thermo-mechanical loading of devices. In this context, the present study assesses the conceptual design quality of the new LHC injection dump, the Target Dump Injection Segmented (TDIS), from an electromagnetic and thermo-mechanical perspective. This contribution analyzes the thermo-mechanical response of the device considering two cases: an accidental beam impact scenario and another accidental scenario with complete failure of the RF-contacts. Further, this paper presents the preliminary results for the simulation of the energy deposited by the two counter-rotating beams circulating in the device.
	Slides TUP2WE04 [10.895 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP2WE04
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TUA2WD02	High-Power Beam Operation at J-PARC	operation, resonance, injection, proton	147
	S. Igarashi KEK, Ibaraki, Japan
	The Japan Proton Accelerator Research Complex (J-PARC) is a multipurpose high-power proton accelerator facility, comprising a 400 MeV linac, a 3 GeV rapid cycling synchrotron (RCS) and a 30 GeV main ring synchrotron (MR). RCS is now providing 500 kW beams to the materials and life science experimental facility (MLF) and its beam power will be increased step by step toward the design value of 1 MW. MR has been operated with the beam power of 500 kW at maximum for the long-baseline neutrino oscillation experiment (T2K). An upgrade plan of MR for the beam power of 1.3 MW for the T2K experiment is promoted with a faster cycling scheme.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUA2WD02
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TUP1WA03	Beam Instabilities After Injection to the LHC	injection, emittance, controls, operation	163
	H. Timko, T. Argyropoulos, I. Karpov, E.N. Shaposhnikova CERN, Geneva, Switzerland
	Long-lasting phase oscillations have been observed at injection into the LHC since its first start-up with beam. These oscillations, however, were not leading to noticeable losses or blow-up in operation, and were therefore not studied in detail. In 2017, dedicated measurements with high-intensity bunches revealed that oscillations can lead to losses even slightly below the baseline intensity for the high-luminosity upgrade of the LHC. For the first time, high-resolution bunch profile acquisitions were triggered directly at injection and the formation of large-amplitude non-rigid dipole oscillations was observed on a turn-by-turn basis. First simulations can reproduce this instability via bunch filamentation that takes place after injection, depending on the mismatch between the bunch and bucket size in momentum at injection.
	Slides TUP1WA03 [2.166 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP1WA03
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TUP2WA02	Momentum Slip-Stacking Simulations for CERN SPS Ion Beams with Collective Effects	emittance, flattop, ECR, cavity	174
	D. Quartullo, T. Argyropoulos, A. Lasheen CERN, Geneva, Switzerland
	The LHC Injectors Upgrade (LIU) Project at CERN aims at doubling the total intensity of the Pb-ion beam for the High-Luminosity LHC (HL-LHC) project. This goal can be achieved by using momentum slip-stacking (MSS) in the SPS, the LHC injector. This RF gymnastics, originally proposed to increase bunch intensity, will be used on the intermediate energy plateau to interleave two batches, reducing the bunch spacing from 100 to 50 ns. The MSS feasibility can be tested only in 2021, after the beam controls upgrade of the SPS 200 MHz RF system, so beam dynamics simulations are used to design this complicated beam manipulation. Simulations of the MSS were performed using the CERN BLonD code with a full SPS impedance model. Attention has been paid to the choice of the RF and machine parameters (beam energy, time duration, RF frequency and voltage programmes) to reduce losses and the final bunch length which is crucial for the injection into the LHC 400 MHz buckets. The initial beam parameters used in simulations were obtained from beam measurements in the first part of the SPS cycle taking into account bunch-by-bunch losses on flat bottom and development of bunch instabilities.
	Slides TUP2WA02 [8.272 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP2WA02
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TUP2WA03	Studies of Capture and Flat-Bottom Losses in the SPS	impedance, optics, injection, beam-loading	180
	M. Schwarz, H. Bartosik, E. Chapochnikova, A. Lasheen, J. Repond, H. Timko CERN, Geneva, Switzerland
	One of the strong limitations for reaching higher beam intensities in the SPS, the injector of the LHC at CERN, are particle losses at flat bottom that increase with beam intensity. In this paper, different sources of these losses are investigated for two available SPS optics, using both measurements and simulations. Part of the losses originate from the PS-to-SPS bunch-to-bucket transfer, because the PS bunches are rotated in longitudinal phase space before injection and do not completely fit into the SPS RF bucket. The injection losses due to different injected bunch distributions were analyzed. Furthermore, at high intensities the transient beam loading in the SPS has a strong impact, which is (partially) compensated by the LLRF system. The effect of the present and future upgraded one-turn delay feedback system and phase loop on flat-bottom losses was studied using the longitudinal tracking code BLonD. Finally, the total particle losses are also affected by limitations in the SPS momentum aperture, visible for higher RF capture voltages in optics with lower transition energy and higher dispersion.
	Slides TUP2WA03 [8.038 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP2WA03
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TUP2WA04	Dynamic Vacuum Simulation for the BRing	vacuum, extraction, synchrotron, injection	186
	P. Li, Z. Dong, M. Li, J.C. Yang IMP/CAS, Lanzhou, People's Republic of China L.H.J. Bozyk GSI, Darmstadt, Germany
	Funding: Youth Innovation Promotion Association of Chinese Academy of Sciences 2016364, National Natural Science Foundation of China (Project No. 11675235). Large dynamic vacuum pressure rises of orders of magnitude which caused by the lost heavy ions can seriously limit the ion intensity and beam lifetime of the heavy ion accelerator, especially for the machine that operate the intermediate charge state heavy ion. The High Intensity heavy ion Accelerator Facility (HIAF) which will be built by the IMP will accumulate the intermediate charge state ion 238U³⁵⁺ to intensity 210¹¹ ppp to different terminals. In order to control the dynamic vacuum effects induced by the lose beams and design the collimation system for the BRing of the HIAF, a newly developed simulation program (ColBeam) and GSI's simulation code StrahlSim are both conducted and the dynamic vacuum simulation result is calculated by the StrahlSim. According to the simulation result, 310¹¹ ppp particles is the up limit beam intensity can be extracted for the current BRing vacuum system design. Higher beam intensity can be reach to 510¹¹ ppp when the NEG coating technology must be implemented for the dipole and quadrupole chamber. HIAF, Collimation, Dynamic vacuum*
	Slides TUP2WA04 [9.947 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP2WA04
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TUP2WA05	Effect of the Extraction Kickers on the Beam Stability in the CERN SPS	impedance, kicker, extraction, cavity	189
	A. Farricker, M.S. Beck, J. Repond, C. Vollinger CERN, Geneva, Switzerland
	Longitudinal beam instability in the CERN SPS is a major limitation in the ability to achieve the bunch intensities required for the goals of the High-Luminosity LHC project (HL-LHC). One of the major drivers in limiting the intensity of the machine is the broadband contribution to the beam-coupling impedance due to the kicker magnets. The extraction kickers (MKE) discussed in this paper are known to give a significant contribution to the overall longitudinal beam-coupling impedance. We present the results of bench measurements of the MKE's impedance to determine the accuracy of electromagnetic simulation models from which the impedance modelused for beam dynamics simulationsis constructed. In addition, we discuss the feasibility and implementation of beam measurements that can indicate the contribution of the MKE magnets to the longitudinal beam-coupling impedance of the SPS.
	Slides TUP2WA05 [2.698 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-TUP2WA05
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WEA1PL01	What is Missing for the Design and Operation of High-Power Linacs?	linac, cavity, operation, lattice	195
	A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA
	Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy. The design process, tuning, and operation of high-power linacs are discussed. The inconsistencies between the basic beam physics principles used in the design and the operation practices are considered. The missing components of the beam physics tools for the design and operations are examined, especially for negative hydrogen ions linacs. The diagnostics and online models necessary for tuning and characterization of existing states of the linac are discussed.
	Slides WEA1PL01 [3.294 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEA1PL01
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WEP1WB02	Beam Dynamics Simulation and Measurements for the IFMIF/EVEDA Project	rfq, space-charge, emittance, proton	210
	M. Comunian, L. Antoniazzi, A. Baldo, C. Baltador, L. Bellan, D. Bortolato, M. Cavenago, E. Fagotti, M.G. Giacchini, F. Grespan, M. Montis, A. Palmieri, A. Pisent, F. Scantamburlo INFN/LNL, Legnaro (PD), Italy L. Bellan Univ. degli Studi di Padova, Padova, Italy N. Chauvin IRFU, CEA, University Paris-Saclay, Gif-sur-Yvette, France H. Dzitko F4E, Germany
	In the framework of IFMIF/EVEDA project the source and RFQ are ready to be tested with beam. In this article the beam dynamics simulation and the measurement performed in preparation of the first beam injection are presented. The installed line is composed by the proton and deuteron Source with the LEBT composed of two solenoids that inject in the 10 meters long RFQ, the MEBT, diagnostic plate and the beam dump. The line is prepared to be tested with protons of 8 mA in pulsed mode (up to 0.1%).
	Slides WEP1WB02 [10.303 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEP1WB02
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WEA1WA01	Sum Resonances with Space Charge	resonance, space-charge, coherent-effects, experiment	226
	G. Franchetti GSI, Darmstadt, Germany
	This presentation will discuss the extension of the theory of the sum resonances with space charge.
	Slides WEA1WA01 [5.267 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEA1WA01
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WEA2WA01	High Intensity Effects of Fixed Target Beams in the CERN Injector Complex	impedance, space-charge, proton, emittance	237
	E. Koukovini-Platia, H. Bartosik, M. Migliorati, G. Rumolo CERN, Geneva, Switzerland M. Migliorati INFN-Roma1, Rome, Italy M. Migliorati Sapienza University of Rome, Rome, Italy
	The current fixed target (FT) experiments at CERN are a complementary approach to the Large Hadron Collider (LHC) and play a crucial role in the investigation of fundamental questions in particle physics. Within the scope of the LHC Injectors Upgrade (LIU), aiming to improve the LHC beam production, the injector complex will be significantly upgraded during the second Long Shutdown (LS2). All non-LHC beams are expected to benefit from these upgrades. In this paper, we focus on the studies of the transverse instability in the Proton Synchrotron (PS), currently limiting the intensity of Time-Of-Flight (ToF) type beams, as well as the prediction of the impact of envisaged hardware modifications. A first discussion on the effect of space charge on the observed instability is also being presented.
	Slides WEA2WA01 [2.483 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEA2WA01
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WEA2WA04	Space-Charge Compensation Using Electron Columns at IOTA	electron, space-charge, proton, plasma	247
	B.T. Freemire Northern Illinois University, DeKalb, Illinois, USA S. Chattopadhyay Northern Illinois Univerity, DeKalb, Illinois, USA M. Chung UNIST, Ulsan, Republic of Korea C.S. Park, V.D. Shiltsev, G. Stancari Fermilab, Batavia, Illinois, USA G. Penn LBNL, Berkeley, California, USA
	Funding: US Department of Energy contracts DE-AC02-07CH11359 and DE-AC02-05CH1123 and the GARD Program. Beam loss due to space charge is a major problem at current and future high intensity particle accelerators. The space charge force can be compensated for proton or ion beams by creating a column of electrons with a charge distribution matched to that of the beam, maintaining electron-proton stability. The column is created by the beam ionizing short sections of high pressure gas. The ionization electrons are then shaped appropriately using electric and magnetic fields. The Integrable Optics Test Accelerator (IOTA) at Fermilab is a test bed for beam loss and instability mitigation techniques. Simulations using the particle-in-cell code, Warp, have been made to track the evolution of both the electron column and the beam over multiple passes. A 2.5 MeV proton beamline is under construction at IOTA, to be used to study the effect of the electron column on a space charge dominated beam.
	Slides WEA2WA04 [8.501 MB]
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WEP2PO007	Multi-Particle Simulations of the Future CERN PSB Injection Process with Updated Linac4 Beam Performance	injection, linac, emittance, optics	278
	V. Forte, C. Bracco, G.P. Di Giovanni, M.A. Fraser, A.M. Lombardi, B. Mikulec CERN, Geneva, Switzerland
	In the framework of the LHC Injectors Upgrade (LIU) project, the injection process in the CERN Proton Synchrotron Booster (PSB) will be renovated after the connection with the Linac4. A new H⁻ charge exchange injection system using a stripping foil is foreseen to increase the brightness of the stored beams and to provide high flexibility in terms of emittance tailoring at 160 MeV. Realistic multi-particle simulations of the future injection processes for high brightness beams (i.e. for the LHC) and high intensity beams (i.e. for the ISOLDE experiment) are presented in this paper. The simulations are based on the present performance of Linac4 and include scattering induced by the foil, space charge effects and compensation of the lattice perturbation introduced by the bumpers of the injection chicane.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEP2PO007
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WEP2PO011	Studies of Transverse Instabilities in the CERN SPS	emittance, octupole, optics, injection	291
	M.S. Beck, H. Bartosik, M. Carlà, K.S.B. Li, G. Rumolo, M. Schenk CERN, Geneva, Switzerland U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	In the framework of the LHC Injectors Upgrade (LIU), beams with about twice the intensity compared to the present values will have to be accelerated by the CERN Super Proton Synchrotron (SPS) and extracted towards the Large Hadron Collider (LHC). Machine studies with intensity higher than the nominal LHC beam have shown that coherent instabilities in both transverse planes may develop at injection energy, potentially becoming a limitation for the future high intensity operation. In particular, a transverse mode coupling instability is encountered in the vertical plane, the threshold of which can be sufficiently increased by changing the machine optics. In addition, a headtail instability of individual bunches is observed in the horizontal plane in multi-bunch operation, which requires stabilization by high chromaticity. The PyHEADTAIL code has been used to check if the present SPS impedance model reproduces the experimental observations. The instability growth rates have been studied for different machine optics configurations and different chromaticity settings. Other stabilizing mechanisms like tune spread from octupoles or the transverse damper have also been investigated.
	Poster WEP2PO011 [4.940 MB]
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WEP2PO030	A 4D Emittance Measurement Device for the 870 keV HIPA Injection Line	cyclotron, proton, space-charge, operation	329
	R. Dölling, M. Rohrer PSI, Villigen PSI, Switzerland
	A 4D emittance measurement device has recently been installed in PSI's high intensity proton accelerator (HIPA) after the acceleration tube of the Cockcroft-Walton pre-accelerator. A pinhole collimator is moved 2D transversally and at each collimator position, the resulting beamlet is downstream scanned 2D by vertically moving over it a horizontal linear array of small electrodes. The properties of this setup and the intended use are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-WEP2PO030
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THP2WB02	High-Intensity Beam Dynamics Simulation of the IFMIF-like Accelerators	space-charge, emittance, beam-transport, rfq	373
	S.H. Moon, M. Chung UNIST, Ulsan, Republic of Korea
	Funding: This research was supported by the National Research Foundation of Korea (Grant No. NRF-2017M1A7A1A02016413). The IFMIF (International Fusion Material Irradiation Facility) project is being considered to build fusion material test facility. The IFMIF will use two accelerators to generate high energy neutrons. However, the IFMIF accelerators have been designed to have much higher beam power and beam current than the existing accelerators, so space charge effect is very strong. This raises big concerns about beam loss and beam transport stability, thus detailed high-intensity beam dynamics study of the IFMIF-like accelerators is indispensable. This research aims to perform source to target simulation of the IFMIF-like accelerator. The simulation has been carried out by two different kinds of simulation codes because the IFMIF accelerator has distinctive features. One is TRACEWIN simulation code which was used in IFMIF initial design. The other is WARP 3D PIC code which can precisely calculate space charge effects. This presentation will focus on beam simulations for LEBT, RFQ, and MEBT of the IFMIF accelerator
	Slides THP2WB02 [10.583 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THP2WB02
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THA2WE02	Application of Machine Learning for the IPM-Based Profile Reconstruction	electron, network, space-charge, detector	410
	M. Sapinski, R. Singh, D.M. Vilsmeier GSI, Darmstadt, Germany J.W. Storey CERN, Geneva, Switzerland
	One of the most reliable devices to measure the transverse beam profile in hadron machines is Ionization Profile Monitor (IPM). This type of monitor can work in two modes: collecting electrons or ions. Typically, for lower intensity beams, the ions produced by ionization of the rest gas are extracted towards a position-sensitive detector. Ion trajectories follow the external electric field lines, however the field of the beam itself also affects their movement leading to a deformation of the observed beam profile. Correction methods for this case are known. For high brightness beams, IPM configuration in which electrons are measured, is typically used. In such mode, an external magnetic field is often applied in order to confine the transverse movement of electrons. However, for extreme beams, the distortion of the measured beam profile can still be present. The dynamics of electron movement is more complex than in case of ions, therefore the correction of the profile distortion is more difficult. Investigation of this problem using a dedicated simulation tool and machine learning algorithms lead to a beam profile correction methods for electron-collecting IPMs.
	Slides THA2WE02 [7.357 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THA2WE02
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Paper

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Other Keywords

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MOA1PL01

Challenges in Understanding Space Charge Dynamics

space-charge, resonance, emittance, synchrotron

1

H. Bartosik
CERN, Geneva, Switzerland

Space charge effects in high intensity and high brightness synchrotrons can lead to undesired beam emittance growth, beam halo formation and particle loss. A series of dedicated machine experiments has been performed over the past decade in order to study these effects in the particular regime of long-term beam storage (10⁵-10⁶ turns) as required for certain applications. This paper gives an overview of the present understanding of the underlying beam dynamics mechanisms. In particular it focuses on the space charge induced periodic resonance crossing, which has been identified as the main mechanism causing beam degradation in this regime. The challenges in further progressing with the understanding, the modelling and the mitigation of these space charge effects and the resulting beam degradation are discussed. Furthermore, an outlook for possible future directions of studies is presented.

Slides MOA1PL01 [22.877 MB]

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MOP2WA03

Experiments and Theory on Beam Stabilization with Second-Order Chromaticity

impedance, damping, experiment, betatron

32

M. Schenk, X. Buffat, L.R. Carver, K.S.B. Li, E. Métral
CERN, Geneva, Switzerland
A. Maillard
ENS, Paris, France

This study reports on an alternative method to generate transverse Landau damping to suppress coherent instabilities in circular accelerators. The incoherent betatron tune spread can be produced through detuning with longitudinal rather than transverse action. This approach is motivated by the high-brightness, low transverse emittance beams in future colliders where detuning with transverse amplitude will be less effective. Detuning with longitudinal action can be introduced with a radio frequency (rf) quadrupole, or similarly, using second-order chromaticity. The latter was enhanced in the Large Hadron Collider (LHC) at CERN and experimental results on single-bunch stabilization are briefly recapped. The observations are interpreted analytically by extending the Vlasov formalism to include nonlinear chromaticity. Finally, the newly developed theory is benchmarked against circulant matrix and particle tracking models.

Slides MOP2WA03 [3.374 MB]

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MOP2WA05

Simulation and Measurement of the TMCI Threshold in the LHC

impedance, coupling, operation, synchrotron

43

D. Amorim, S. A. Antipov, N. Biancacci, X. Buffat, L.R. Carver, E. Métral
CERN, Geneva, Switzerland

The transverse mode coupling instability occurs in individual bunches when two transverse oscillation modes couple at high intensity. Simulations predict an instability threshold in the LHC at a single bunch intensity of 3*10¹¹ protons. The TMCI threshold can be inferred by measuring the tune shift as a function of intensity. This measurement was performed in the LHC for different machine impedances and bunch intensities. The impedance was changed by varying the primary and secondary collimators gaps to increase their contribution to the resistive wall impedance. The experiment also allowed to assess the validity of the LHC impedance model in the single bunch case.

Slides MOP2WA05 [4.729 MB]

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MOP1WB03

Experimental Study of Beam Dynamics in the PIP-II MEBT Prototype

rfq, cavity, optics, emittance

54

A.V. Shemyakin, J.-P. Carneiro, B.M. Hanna, V.A. Lebedev, L.R. Prost, A. Saini, V.E. Scarpine
Fermilab, Batavia, Illinois, USA
C.J. Richard
NSCL, East Lansing, Michigan, USA
V.L. Sista
BARC, Mumbai, India

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics
The Proton Improvement Plan, Stage Two (PIP-II) is a program of upgrades proposed for the Fermilab injection complex, which central part is an 800-MeV, 2-mA CW SRF linac. A prototype of the PIP-II linac front end called PIP-II Injector Test (PIP2IT) is being built at Fermilab. As of now, a 15-mA DC, 30-keV H⁻ ion source, a 2 m-long Low Energy Beam Transport (LEBT), a 2.1-MeV CW RFQ, followed by a 10-m Medium Energy Beam Transport (MEBT) have been assembled and commissioned. The MEBT bunch-by-bunch chopping system and the requirement of a low uncontrolled beam loss put stringent limitations on the beam envelope and its variation. Measurements of transverse and longitudinal beam dynamics in the MEBT were performed in the range of 1-10 mA of the RFQ beam current. Almost all measurements are made with 10 μs beam pulses in order to avoid damage to the beam line. This report presents measurements of the transverse optics with differential trajectories, reconstruction of the beam envelope with scrapers and an Allison emittance scanner, as well as bunch length measurements with a Fast Faraday Cup.

Slides MOP1WB03 [3.750 MB]

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MOP2WB01

60 mA Beam Study in J-PARC Linac

DTL, rfq, linac, lattice

60

Y. Liu
KEK/JAEA, Ibaraki-Ken, Japan
A. Miura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
T. Miyao
KEK, Ibaraki, Japan
M. Otani, T. Shibata
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Upgrade of Linac peak current from 50 mA to 60 mA is one of the keys to the next power upgrade in J-PARC. Beam studies with 60 mA were carried out in July and December, 2017, for the challenging issues such as investigation of beam property from the ion source, halo behavior throughout the LEBT, RFQ and MEBT1, emittance/Twiss measurement at MEBT1, beam emittance control, etc. Expected/unexpected problems, intermediate results and preparation for the next trials were introduced in this paper.

Slides MOP2WB01 [12.952 MB]

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MOP2WB02

Simulation and Measurement Campaigns for Characterization and Performance Improvement of the CERN Heavy Ion Linac3

linac, extraction, rfq, emittance

64

G. Bellodi, S. Benedetti, D. Küchler, F.J.C. Wenander
CERN, Geneva, Switzerland
V. Toivanen
GANIL, Caen, France

In the framework of the LHC Injector Upgrade programme (LIU), several activities have been carried out to improve the GTS-LHC ion source and Linac3 performance (Linac3 providing the charged heavy ion beams for CERN exper-iments). A restudy of the beam dynamics and transport through the linac was initiated, through a campaign of systematic machine measurements and parallel beam simulations, generalising techniques developed for beam characterization during Linac4 commissioning. The work here presented will review the most relevant findings and lessons learnt in the process.

Slides MOP2WB02 [17.512 MB]

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TUP2WE04

Design of the Target Dump Injection Segmented (TDIS) in the Framework of the High Luminosity Large Hadron Collider (HL-LHC) Project

injection, site, shielding, impedance

122

L. Teofili, D. Carbajo Perez, I. Lamas Garcia, M. Migliorati, A. Perillo
CERN, Geneva, Switzerland
M. Migliorati
INFN-Roma1, Rome, Italy
M. Migliorati
Sapienza University of Rome, Rome, Italy

The High Luminosity Large Hadron Collider (HL-LHC) Project at CERN calls for increasing beam brightness and intensity. In this scenario most equipment has to be redesigned and rebuilt. In particular, beam intercepting devices (as dumps, collimators, absorbers and scrapers) have to withstand impact or scraping of the new intense HL-LHC beams without failures. Further, minimizing the electromagnetic beam-device interactions is also a key design driver since they can lead to beam instabilities and excessive thermo-mechanical loading of devices. In this context, the present study assesses the conceptual design quality of the new LHC injection dump, the Target Dump Injection Segmented (TDIS), from an electromagnetic and thermo-mechanical perspective. This contribution analyzes the thermo-mechanical response of the device considering two cases: an accidental beam impact scenario and another accidental scenario with complete failure of the RF-contacts. Further, this paper presents the preliminary results for the simulation of the energy deposited by the two counter-rotating beams circulating in the device.

Slides TUP2WE04 [10.895 MB]

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TUA2WD02

High-Power Beam Operation at J-PARC

operation, resonance, injection, proton

147

S. Igarashi
KEK, Ibaraki, Japan

The Japan Proton Accelerator Research Complex (J-PARC) is a multipurpose high-power proton accelerator facility, comprising a 400 MeV linac, a 3 GeV rapid cycling synchrotron (RCS) and a 30 GeV main ring synchrotron (MR). RCS is now providing 500 kW beams to the materials and life science experimental facility (MLF) and its beam power will be increased step by step toward the design value of 1 MW. MR has been operated with the beam power of 500 kW at maximum for the long-baseline neutrino oscillation experiment (T2K). An upgrade plan of MR for the beam power of 1.3 MW for the T2K experiment is promoted with a faster cycling scheme.

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TUP1WA03

Beam Instabilities After Injection to the LHC

injection, emittance, controls, operation

163

H. Timko, T. Argyropoulos, I. Karpov, E.N. Shaposhnikova
CERN, Geneva, Switzerland

Long-lasting phase oscillations have been observed at injection into the LHC since its first start-up with beam. These oscillations, however, were not leading to noticeable losses or blow-up in operation, and were therefore not studied in detail. In 2017, dedicated measurements with high-intensity bunches revealed that oscillations can lead to losses even slightly below the baseline intensity for the high-luminosity upgrade of the LHC. For the first time, high-resolution bunch profile acquisitions were triggered directly at injection and the formation of large-amplitude non-rigid dipole oscillations was observed on a turn-by-turn basis. First simulations can reproduce this instability via bunch filamentation that takes place after injection, depending on the mismatch between the bunch and bucket size in momentum at injection.

Slides TUP1WA03 [2.166 MB]

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TUP2WA02

Momentum Slip-Stacking Simulations for CERN SPS Ion Beams with Collective Effects

emittance, flattop, ECR, cavity

174

D. Quartullo, T. Argyropoulos, A. Lasheen
CERN, Geneva, Switzerland

The LHC Injectors Upgrade (LIU) Project at CERN aims at doubling the total intensity of the Pb-ion beam for the High-Luminosity LHC (HL-LHC) project. This goal can be achieved by using momentum slip-stacking (MSS) in the SPS, the LHC injector. This RF gymnastics, originally proposed to increase bunch intensity, will be used on the intermediate energy plateau to interleave two batches, reducing the bunch spacing from 100 to 50 ns. The MSS feasibility can be tested only in 2021, after the beam controls upgrade of the SPS 200 MHz RF system, so beam dynamics simulations are used to design this complicated beam manipulation. Simulations of the MSS were performed using the CERN BLonD code with a full SPS impedance model. Attention has been paid to the choice of the RF and machine parameters (beam energy, time duration, RF frequency and voltage programmes) to reduce losses and the final bunch length which is crucial for the injection into the LHC 400 MHz buckets. The initial beam parameters used in simulations were obtained from beam measurements in the first part of the SPS cycle taking into account bunch-by-bunch losses on flat bottom and development of bunch instabilities.

Slides TUP2WA02 [8.272 MB]

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TUP2WA03

Studies of Capture and Flat-Bottom Losses in the SPS

impedance, optics, injection, beam-loading

180

M. Schwarz, H. Bartosik, E. Chapochnikova, A. Lasheen, J. Repond, H. Timko
CERN, Geneva, Switzerland

One of the strong limitations for reaching higher beam intensities in the SPS, the injector of the LHC at CERN, are particle losses at flat bottom that increase with beam intensity. In this paper, different sources of these losses are investigated for two available SPS optics, using both measurements and simulations. Part of the losses originate from the PS-to-SPS bunch-to-bucket transfer, because the PS bunches are rotated in longitudinal phase space before injection and do not completely fit into the SPS RF bucket. The injection losses due to different injected bunch distributions were analyzed. Furthermore, at high intensities the transient beam loading in the SPS has a strong impact, which is (partially) compensated by the LLRF system. The effect of the present and future upgraded one-turn delay feedback system and phase loop on flat-bottom losses was studied using the longitudinal tracking code BLonD. Finally, the total particle losses are also affected by limitations in the SPS momentum aperture, visible for higher RF capture voltages in optics with lower transition energy and higher dispersion.

Slides TUP2WA03 [8.038 MB]

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TUP2WA04

Dynamic Vacuum Simulation for the BRing

vacuum, extraction, synchrotron, injection

186

P. Li, Z. Dong, M. Li, J.C. Yang
IMP/CAS, Lanzhou, People's Republic of China
L.H.J. Bozyk
GSI, Darmstadt, Germany

Funding: Youth Innovation Promotion Association of Chinese Academy of Sciences 2016364, National Natural Science Foundation of China (Project No. 11675235).
Large dynamic vacuum pressure rises of orders of magnitude which caused by the lost heavy ions can seriously limit the ion intensity and beam lifetime of the heavy ion accelerator, especially for the machine that operate the intermediate charge state heavy ion. The High Intensity heavy ion Accelerator Facility (HIAF) which will be built by the IMP will accumulate the intermediate charge state ion 238U³⁵⁺ to intensity 2*10¹¹ ppp to different terminals. In order to control the dynamic vacuum effects induced by the lose beams and design the collimation system for the BRing of the HIAF, a newly developed simulation program (ColBeam) and GSI's simulation code StrahlSim are both conducted and the dynamic vacuum simulation result is calculated by the StrahlSim. According to the simulation result, 3*10¹¹ ppp particles is the up limit beam intensity can be extracted for the current BRing vacuum system design. Higher beam intensity can be reach to 5*10¹¹ ppp when the NEG coating technology must be implemented for the dipole and quadrupole chamber.
HIAF, Collimation, Dynamic vacuum

Slides TUP2WA04 [9.947 MB]

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TUP2WA05

Effect of the Extraction Kickers on the Beam Stability in the CERN SPS

impedance, kicker, extraction, cavity

189

A. Farricker, M.S. Beck, J. Repond, C. Vollinger
CERN, Geneva, Switzerland

Longitudinal beam instability in the CERN SPS is a major limitation in the ability to achieve the bunch intensities required for the goals of the High-Luminosity LHC project (HL-LHC). One of the major drivers in limiting the intensity of the machine is the broadband contribution to the beam-coupling impedance due to the kicker magnets. The extraction kickers (MKE) discussed in this paper are known to give a significant contribution to the overall longitudinal beam-coupling impedance. We present the results of bench measurements of the MKE's impedance to determine the accuracy of electromagnetic simulation models from which the impedance modelused for beam dynamics simulationsis constructed. In addition, we discuss the feasibility and implementation of beam measurements that can indicate the contribution of the MKE magnets to the longitudinal beam-coupling impedance of the SPS.

Slides TUP2WA05 [2.698 MB]

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WEA1PL01

What is Missing for the Design and Operation of High-Power Linacs?

linac, cavity, operation, lattice

195

A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA

Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy.
The design process, tuning, and operation of high-power linacs are discussed. The inconsistencies between the basic beam physics principles used in the design and the operation practices are considered. The missing components of the beam physics tools for the design and operations are examined, especially for negative hydrogen ions linacs. The diagnostics and online models necessary for tuning and characterization of existing states of the linac are discussed.

Slides WEA1PL01 [3.294 MB]

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WEP1WB02

Beam Dynamics Simulation and Measurements for the IFMIF/EVEDA Project

rfq, space-charge, emittance, proton

210

M. Comunian, L. Antoniazzi, A. Baldo, C. Baltador, L. Bellan, D. Bortolato, M. Cavenago, E. Fagotti, M.G. Giacchini, F. Grespan, M. Montis, A. Palmieri, A. Pisent, F. Scantamburlo
INFN/LNL, Legnaro (PD), Italy
L. Bellan
Univ. degli Studi di Padova, Padova, Italy
N. Chauvin
IRFU, CEA, University Paris-Saclay, Gif-sur-Yvette, France
H. Dzitko
F4E, Germany

In the framework of IFMIF/EVEDA project the source and RFQ are ready to be tested with beam. In this article the beam dynamics simulation and the measurement performed in preparation of the first beam injection are presented. The installed line is composed by the proton and deuteron Source with the LEBT composed of two solenoids that inject in the 10 meters long RFQ, the MEBT, diagnostic plate and the beam dump. The line is prepared to be tested with protons of 8 mA in pulsed mode (up to 0.1%).

Slides WEP1WB02 [10.303 MB]

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WEA1WA01

Sum Resonances with Space Charge

resonance, space-charge, coherent-effects, experiment

226

G. Franchetti
GSI, Darmstadt, Germany

This presentation will discuss the extension of the theory of the sum resonances with space charge.

Slides WEA1WA01 [5.267 MB]

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WEA2WA01

High Intensity Effects of Fixed Target Beams in the CERN Injector Complex

impedance, space-charge, proton, emittance

237

E. Koukovini-Platia, H. Bartosik, M. Migliorati, G. Rumolo
CERN, Geneva, Switzerland
M. Migliorati
INFN-Roma1, Rome, Italy
M. Migliorati
Sapienza University of Rome, Rome, Italy

The current fixed target (FT) experiments at CERN are a complementary approach to the Large Hadron Collider (LHC) and play a crucial role in the investigation of fundamental questions in particle physics. Within the scope of the LHC Injectors Upgrade (LIU), aiming to improve the LHC beam production, the injector complex will be significantly upgraded during the second Long Shutdown (LS2). All non-LHC beams are expected to benefit from these upgrades. In this paper, we focus on the studies of the transverse instability in the Proton Synchrotron (PS), currently limiting the intensity of Time-Of-Flight (ToF) type beams, as well as the prediction of the impact of envisaged hardware modifications. A first discussion on the effect of space charge on the observed instability is also being presented.

Slides WEA2WA01 [2.483 MB]

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WEA2WA04

Space-Charge Compensation Using Electron Columns at IOTA

electron, space-charge, proton, plasma

247

B.T. Freemire
Northern Illinois University, DeKalb, Illinois, USA
S. Chattopadhyay
Northern Illinois Univerity, DeKalb, Illinois, USA
M. Chung
UNIST, Ulsan, Republic of Korea
C.S. Park, V.D. Shiltsev, G. Stancari
Fermilab, Batavia, Illinois, USA
G. Penn
LBNL, Berkeley, California, USA

Funding: US Department of Energy contracts DE-AC02-07CH11359 and DE-AC02-05CH1123 and the GARD Program.
Beam loss due to space charge is a major problem at current and future high intensity particle accelerators. The space charge force can be compensated for proton or ion beams by creating a column of electrons with a charge distribution matched to that of the beam, maintaining electron-proton stability. The column is created by the beam ionizing short sections of high pressure gas. The ionization electrons are then shaped appropriately using electric and magnetic fields. The Integrable Optics Test Accelerator (IOTA) at Fermilab is a test bed for beam loss and instability mitigation techniques. Simulations using the particle-in-cell code, Warp, have been made to track the evolution of both the electron column and the beam over multiple passes. A 2.5 MeV proton beamline is under construction at IOTA, to be used to study the effect of the electron column on a space charge dominated beam.

Slides WEA2WA04 [8.501 MB]

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WEP2PO007

Multi-Particle Simulations of the Future CERN PSB Injection Process with Updated Linac4 Beam Performance

injection, linac, emittance, optics

278

V. Forte, C. Bracco, G.P. Di Giovanni, M.A. Fraser, A.M. Lombardi, B. Mikulec
CERN, Geneva, Switzerland

In the framework of the LHC Injectors Upgrade (LIU) project, the injection process in the CERN Proton Synchrotron Booster (PSB) will be renovated after the connection with the Linac4. A new H⁻ charge exchange injection system using a stripping foil is foreseen to increase the brightness of the stored beams and to provide high flexibility in terms of emittance tailoring at 160 MeV. Realistic multi-particle simulations of the future injection processes for high brightness beams (i.e. for the LHC) and high intensity beams (i.e. for the ISOLDE experiment) are presented in this paper. The simulations are based on the present performance of Linac4 and include scattering induced by the foil, space charge effects and compensation of the lattice perturbation introduced by the bumpers of the injection chicane.

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WEP2PO011

Studies of Transverse Instabilities in the CERN SPS

emittance, octupole, optics, injection

291

M.S. Beck, H. Bartosik, M. Carlà, K.S.B. Li, G. Rumolo, M. Schenk
CERN, Geneva, Switzerland
U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

In the framework of the LHC Injectors Upgrade (LIU), beams with about twice the intensity compared to the present values will have to be accelerated by the CERN Super Proton Synchrotron (SPS) and extracted towards the Large Hadron Collider (LHC). Machine studies with intensity higher than the nominal LHC beam have shown that coherent instabilities in both transverse planes may develop at injection energy, potentially becoming a limitation for the future high intensity operation. In particular, a transverse mode coupling instability is encountered in the vertical plane, the threshold of which can be sufficiently increased by changing the machine optics. In addition, a headtail instability of individual bunches is observed in the horizontal plane in multi-bunch operation, which requires stabilization by high chromaticity. The PyHEADTAIL code has been used to check if the present SPS impedance model reproduces the experimental observations. The instability growth rates have been studied for different machine optics configurations and different chromaticity settings. Other stabilizing mechanisms like tune spread from octupoles or the transverse damper have also been investigated.

Poster WEP2PO011 [4.940 MB]

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WEP2PO030

A 4D Emittance Measurement Device for the 870 keV HIPA Injection Line

cyclotron, proton, space-charge, operation

329

R. Dölling, M. Rohrer
PSI, Villigen PSI, Switzerland

A 4D emittance measurement device has recently been installed in PSI's high intensity proton accelerator (HIPA) after the acceleration tube of the Cockcroft-Walton pre-accelerator. A pinhole collimator is moved 2D transversally and at each collimator position, the resulting beamlet is downstream scanned 2D by vertically moving over it a horizontal linear array of small electrodes. The properties of this setup and the intended use are discussed.

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THP2WB02

High-Intensity Beam Dynamics Simulation of the IFMIF-like Accelerators

space-charge, emittance, beam-transport, rfq

373

S.H. Moon, M. Chung
UNIST, Ulsan, Republic of Korea

Funding: This research was supported by the National Research Foundation of Korea (Grant No. NRF-2017M1A7A1A02016413).
The IFMIF (International Fusion Material Irradiation Facility) project is being considered to build fusion material test facility. The IFMIF will use two accelerators to generate high energy neutrons. However, the IFMIF accelerators have been designed to have much higher beam power and beam current than the existing accelerators, so space charge effect is very strong. This raises big concerns about beam loss and beam transport stability, thus detailed high-intensity beam dynamics study of the IFMIF-like accelerators is indispensable. This research aims to perform source to target simulation of the IFMIF-like accelerator. The simulation has been carried out by two different kinds of simulation codes because the IFMIF accelerator has distinctive features. One is TRACEWIN simulation code which was used in IFMIF initial design. The other is WARP 3D PIC code which can precisely calculate space charge effects. This presentation will focus on beam simulations for LEBT, RFQ, and MEBT of the IFMIF accelerator

Slides THP2WB02 [10.583 MB]

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THA2WE02

Application of Machine Learning for the IPM-Based Profile Reconstruction

electron, network, space-charge, detector

410

M. Sapinski, R. Singh, D.M. Vilsmeier
GSI, Darmstadt, Germany
J.W. Storey
CERN, Geneva, Switzerland

One of the most reliable devices to measure the transverse beam profile in hadron machines is Ionization Profile Monitor (IPM). This type of monitor can work in two modes: collecting electrons or ions. Typically, for lower intensity beams, the ions produced by ionization of the rest gas are extracted towards a position-sensitive detector. Ion trajectories follow the external electric field lines, however the field of the beam itself also affects their movement leading to a deformation of the observed beam profile. Correction methods for this case are known. For high brightness beams, IPM configuration in which electrons are measured, is typically used. In such mode, an external magnetic field is often applied in order to confine the transverse movement of electrons. However, for extreme beams, the distortion of the measured beam profile can still be present. The dynamics of electron movement is more complex than in case of ions, therefore the correction of the profile distortion is more difficult. Investigation of this problem using a dedicated simulation tool and machine learning algorithms lead to a beam profile correction methods for electron-collecting IPMs.

Slides THA2WE02 [7.357 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-HB2018-THA2WE02

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