Keyword: simulation
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MOPM1P80 Accelerator Physics Challenges in FRIB Driver Linac ion, linac, heavy-ion, ion-source 27
 
  • M. Ikegami, K. Fukushima, Z.Q. He, S.M. Lidia, Z. Liu, S.M. Lund, F. Marti, T. Maruta, D.G. Maxwell, G. Shen, J. Wei, Y. Yamazaki, T. Yoshimoto, Q. Zhao
    FRIB, East Lansing, Michigan, USA
  
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
FRIB is a heavy ion linac facility to accelerate all stable ions to the energy of 200 MeV/u with the beam power of 400 kW, which is under construction at Michigan State University in USA. FRIB driver linac is a beam power frontier accelerator aiming to realize two orders of magnitude higher beam power than existing facilities. It consists of more than 300 low-beta superconducting cavities with unique folded layout to fit into the existing campus with innovative features including multi charge state acceleration. In this talk, we overview accelerator physics challenges in FRIB driver linac with highlight on recent progresses and activities preparing for the coming beam commissioning. 		 
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MOPM3P01 Beam Optics Simulations Study on the Pre-Stripper Linac for Rare Isotope Science Project linac, cryomodule, ion, cavity 31
 
  • J.-W. Kim, J.-H. Jang, H. Jin
    IBS, Daejeon, Republic of Korea
  • Z.A. Conway, B. Mustapha, P.N. Ostroumov
    ANL, Argonne, Illinois, USA
  
  Funding: This work was supported by the Rare Isotope Science Project of the Institute for Basic Science funded by the Ministry of Science, ICT and Future Planning and the National Research Foundation of Korea.
The rare isotope science project (RISP) under development in Korea aims to provide various heavy-ion beams for nuclear and applied science users. A pre-stripper linac is the first superconducting section to be constructed for the acceleration of both stable and radioisotope beams to the energy of 18.5 Mev/u with a DC equivalent voltage of 160 MV. The current baseline design consists of an ECR ion source, an RFQ, cryomodules with QWR and HWR cavities and quadruple focusing magnets in the warm sections between cryomodules. Recently we have developed an alternative design in collaboration with Argonne's Linac Development Group to layout the linac based on state-of-the-art ANL's QWR operating at 81.25 MHz and multi-cavity cryomodules of the type used for the ATLAS upgrade and Fermilab PIP-II projects. End-to-end beam dynamics calculations have been performed to ensure an optimized design with no beam losses. The numbers of required cavities and cryomodules are significantly reduced in the alternative design. The results of beam optics simulations and error sensitivity studies are discussed. 		 
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MOPR001 Figure-8 Storage Ring – Investigation of the Scaled Down Injection System injection, detector, experiment, kicker 41
 
  • H. Niebuhr, A. Ates, M. Droba, O. Meusel, D. Noll, U. Ratzinger, J.F. Wagner
    IAP, Frankfurt am Main, Germany
  
  To store high current ion beams up to 10 A, a superconducting storage ring (F8SR) is planned at Frankfurt university. For the realisation, a scaled down experimental setup with normalconducting magnets is being build. Investigations of beam transport in solenoidal and toroidal guiding fields are in progress. At the moment, a new kind of injection system consisting of a solenoidal injection coil and a special vacuum vessel is under development. It is used to inject a hydrogen beam sideways between two toroidal magnets. In parallel operation, a second hydrogen beam is transported through both magnets to represent the circulating beam. In a second stage, an ExB-Kicker will be used as a septum to combine both beams into one. The current status of the experimental setup will be shown. For the design of the experiments, computer simulations using the 3D simulation code bender were performed. Different input parameters were checked to find the optimal injection and transport channel for the experiment. The results will be presented.  
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MOPR005 RF-Knockout Slow Extraction Design for XiPAF Synchrotron extraction, septum, synchrotron, resonance 52
 
  • H.J. Yao, X. Guan, G.R. Li, X.W. Wang, Q. Zhang, S.X. Zheng
    TUB, Beijing, People's Republic of China
  
  The physics design of slow extraction for Xi’an Proton Application Facility (XiPAF) synchrotron is discussed. The extraction scheme is composed of two resonant sextupoles, one electrostatic septum (ES) and two septum magnets. The phase space diagram under the Hardt condition at the entrance of ES and the last three turn’s trajectory before extraction are presented. A program is written with C++ to simulate slow extraction process by RF-knockout (RF-KO), the calculation results of dual frequency modulation (FM) and amplitude modulation (AM) are given, and the standard deviation of the fluctuation parameter R1 can be limited 0.2 with optimum parameters under a sampling frequency of about 10 kHz.  
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MOPR008 Pressure Profiles Calculation for the CSRm and BRing ion, vacuum, dipole, heavy-ion 62
 
  • P. Li, Z. Chai, Z. Dong, X.C. Kang, M. Li, S. Li, W.L. Li, C.L. Luo, R.S. Mao, J. Meng, J.C. Yang, Y.J. Yuan, W.H. Zheng
    IMP/CAS, Lanzhou, People's Republic of China
  
  Funding: National Natural Science Foundation of China (Project No. 11305227)
A new large scale accelerator facility is being designed by Institute of Modern Physics (IMP) Lanzhou, which is named as the High Intensity heavy-ion Accelerator Facility (HIAF). This project consists of ion sources, Linac accelerator, synchrotrons (BRing) and several experimental terminals. During the operation of Bring, the heavy ion beams will be easily lost at the vacuum chamber along the BRing when it is used to accumulate intermediate charge state particles. The vacuum pressure bump due to the ion-induced desorption in turn leads to an increase in beam loss rate. In order to accumulate the beams to higher intensity to fulfill the requirements of physics experiments and for better understanding of the dynamic vacuum pressure caused by the beam loss, a dynamic vacuum pressure simulation program has been developed. Vacuum pressure profiles are calculated and compared with the measured data based on the current synchrotron (CSRm). Then the static vacuum pressure profiles of the BRing and one type of pump which will be used in the BRing are introduced in this paper. 		 
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MOPR009 Transverse Beam Splitting Made Operational: Recent Progress of the Multi-Turn Extraction at the CERN Proton Synchrotron extraction, proton, septum, synchrotron 65
 
  • A. Huschauer, J.C.C.M. Borburgh, S. Damjanovic, S.S. Gilardoni, M. Giovannozzi, M. Hourican, K. Kahle, G. Le Godec, O. Michels, G. Sterbini
    CERN, Geneva, Switzerland
  • C. Hernalsteens
    IBA, Louvain-la-Neuve, Belgium
  
  Following a successful commissioning period, the Multi-Turn Extraction (MTE) at the CERN Proton Synchrotron (PS) has been applied for the fixed-target physics programme at the Super Proton Synchrotron (SPS) since September 2015. This exceptional extraction technique was proposed to replace the long-serving Continuous Transfer (CT) extraction, which has the drawback of inducing high activation in the ring. MTE exploits the principles of non-linear beam dynamics to perform loss-free beam splitting in the horizontal phase space. Over multiple turns, the resulting beamlets are then transferred to the downstream accelerator. The operational deployment of MTE was rendered possible by the full understanding and mitigation of different hardware limitations and by redesigning the extraction trajectories and non-linear optics, which was required due to the installation of a dummy septum to reduce the activation of the magnetic extraction septum. The results of the related experimental and simulation studies, a summary of the 2015 performance analysis, as well as more recent performance improvements are presented in this paper.  
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MOPR010 Machine Element Contribution to the Longitudinal Impedance Model of the CERN SPS impedance, resonance, coupling, pick-up 71
 
  • T. Kaltenbacher, F. Caspers, C. Vollinger
    CERN, Geneva, Switzerland
  
  This contribution describes the current longitudinal impedance model of the SPS and studies carried out in order to improve, extend and update it. Specifically, new sources of impedances have been identified, evaluated and included in the model. One finding are low Q and low-frequency (LF; here below 1 GHz) resonances which occur due to enamelled flanges in combination with external cabling e.g. ground loops. These resonances couple to the beam through the gap with enamel coating which creates an open resonator. Since this impedance is important for beam stability in the CERN Proton Synchrotron (PS), RF by-passes were installed on the enamelled flanges, and their significance for the SPS beam is currently under investigation. Simulations, bench and beam measurements were used to deduce model parameters for beam dynamic simulations.  
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MOPR011 The SPS 200 MHz TWC Impedance after the LIU Upgrade cavity, HOM, impedance, pick-up 76
 
  • T. Roggen, R. Calaga, F. Caspers, T. Kaltenbacher, C. Vollinger
    CERN, Geneva, Switzerland
  
  Funding: Fellowship co-funded by the European Union as a Marie Curie action (Grant agreement PCOFUND-GA-2010-267194) within the Seventh Framework Programme for Research and Technological Development.
As a part of the LHC Injectors Upgrade project (LIU) the 200 MHz Travelling Wave Cavities (TWC) of the Super Proton Synchrotron (SPS) will be upgraded. The two existing five-section cavities will be rearranged into four three-section cavities (using two existing spare sections), thereby increasing the total voltage from 7 MV (IRF = 1.5 A) to 10 MV (IRF = 3.0 A). Projections of the HL-LHC (High Luminosity Large Hadron Collider) era are conceived by the macro-particle simulation code BLonD, that makes use of an impedance model of the SPS, developed from a thorough survey of machine elements. This paper analyses the impedance contribution of the 200 MHz cavities in the two configurations, using electromagnetic simulations. Measurements of the existing cavities in the SPS and a single-section prototype are also presented. 		 
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MOPR012 The New HL-LHC Injection and Transport Protection System injection, kicker, brightness, proton 81
 
  • F.M. Velotti, W. Bartmann, C. Bracco, M.A. Fraser, B. Goddard, V. Kain, A. Lechner, M. Meddahi
    CERN, Geneva, Switzerland
  
  The High-Luminosity LHC (HL-LHC) upgrade represents a challenge for the full chain of its injectors. The aim is to provide beams with a brightness a factor of two higher than the present maximum achieved. The 450 GeV beams injected into the LHC are directly provided by the Super Proton Synchrotron (SPS) via two transfer lines (TL), TI2 and TI8. Such transfer lines are both equipped with a passive protection system to protect the LHC aperture against ultra-fast failures of the extraction and transport systems. In the LHC instead, the injection protection system protects the cold apertures against possible failures of the injection kicker, MKI. Due to the increase of the beam brightness, these passive systems need to be upgraded. In this paper, the foreseen and ongoing modifications of the LHC injection protection system and the TL collimators are presented. Simulations of the protection guaranteed by the new systems in case of failures are described, together with benchmark with measurements for the current systems.  
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MOPR016 Mitigation of Numerical Noise for Beam Loss Simulations emittance, space-charge, ion, proton 90
 
  • F. Kesting
    IAP, Frankfurt am Main, Germany
  • G. Franchetti
    GSI, Darmstadt, Germany
  
  Numerical noise emerges in self-consistent simulations of charged particles, and its mitigation is investigated since the first numerical studies in plasma physics. In accelerator physics, recent studies find an artificial diffusion of the particle beam due to numerical noise in particle-in-cell tracking, which is of particular importance for high intensity machines with a long storage time, as the SIS100 at FAIR or in context of the LIU upgrade at CERN. In beam loss simulations for these projects artificial effects must be distinguished from physical beam loss. Therefore, it is important to relate artificial diffusion to artificial beam loss, and to choose simulation parameters such that physical beam loss is well resolved. As a practical tool, we therefore suggest a scaling law to find optimal simulation parameters for a given maximum percentage of acceptable artificial beam loss.  
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MOPR020 Space Charge Effects of High Intensity Beams at BRing resonance, emittance, injection, betatron 101
 
  • J. Li, J.C. Yang
    IMP/CAS, Lanzhou, People's Republic of China
  
  Funding: Work supported by NSFC (Grant No. 11475235)
Space charge effects perform one of the main intensity limitations for low energy synchrotron. Large tune spread and crossing resonance stop-bands can hardly be avoided for intensive heavy ion beam at high intensity. Several subjects like Betatron and structure resonance, and tune spread are discussed. Simulations are carried out for 238U34+ focusing on emittance and intensity change during RF capture at the injection energy at the booster ring of the High Intensity heavy ion Accelerator Facility (HIAF).
lijie@impcas.ac.cn 		 
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MOPR021 Overview of the ESSnuSB Accumulator Ring emittance, linac, injection, space-charge 105
 
  • M. Olvegård, T.J.C. Ekelöf
    Uppsala University, Uppsala, Sweden
  • E. Benedetto, M. Cieslak-Kowalska, M. Martini, H.O. Schönauer, E.H.M. Wildner
    CERN, Geneva, Switzerland
  
  The European Spallation Source (ESS) is a research center based on the world’s most powerful proton driver, 2.0 GeV, 5 MW on target, currently under construction in Lund. With an increased pulse frequency, the ESS linac could deliver additional beam pulses to a neutrino target, thus giving an excellent opportunity to produce a high-performance ESS neutrino Super-Beam (ESSnuSB). The focusing system surrounding the neutrino target requires short proton pulses. An accumulator ring and acceleration of an H− beam in the linac for charge-exchange injection into the accumulator could provide such short pulses. In this paper we present an overview of the work with optimizing the accumulator design and the challenges of injecting and storing 1.1015 protons per pulse from the linac. In particular, particle tracking simulations with space charge will be described.  
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MOPR023 Interpretation of Wire-Scanner Asymmetric Profiles in a Low-Energy Ring emittance, space-charge, scattering, booster 115
 
  • M. Cieslak-Kowalska, E. Benedetto
    CERN, Geneva, Switzerland
  
  In the CERN PS Booster, wire-scanner profile measurements performed at injection energy are affected by a strong asymmetry. The shape was reproduced with the code pyOrbit, assuming that the effect is due to the beam evolution during the scans, under the influence of space-charge forces and Multiple Coulomb Scattering at the wire itself. Reproducing the transverse profiles during beam evolution allows to use them reliably as input for simulation benchmarking.  
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MOPR025 Space Charge Modules for PyHEADTAIL GPU, space-charge, emittance, vacuum 124
 
  • A. Oeftiger
    CERN, Geneva, Switzerland
  • S. Hegglin
    ETH, Zurich, Switzerland
  
  Funding: CERN, Doctoral Studentship and EPFL, Doctorate
PyHEADTAIL is a 6D tracking tool developed at CERN to simulate collective effects. We present recent developments of the direct space charge suite, which is available for both the CPU and GPU. A new 3D particle-in-cell solver with open boundary conditions has been implemented. For the transverse plane, there is a semi-analytical Bassetti-Erskine model as well as 2D self-consistent particle-in-cell solvers with both open and closed boundary conditions. For the longitudinal plane, PyHEADTAIL offers line density derivative models. Simulations with these models are benchmarked with experiments at the injection plateau of CERN's Super Proton Synchrotron. 		 
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MOPR028 CERN PS Booster Longitudinal Dynamics Simulations for the Post-LS2 Scenario emittance, space-charge, injection, impedance 140
 
  • D. Quartullo, S.C.P. Albright, E.N. Shaposhnikova, H. Timko
    CERN, Geneva, Switzerland
  
  The CERN PS Booster is the first synchrotron in the LHC proton injection chain, it currently accelerates particles from 50 MeV to 1.4 GeV kinetic energy. Several upgrades foreseen by the LHC Injectors Upgrade Program will allow the beam to be accelerated from 160 MeV to 2 GeV after Long Shutdown 2 in 2021. The present RF systems will be replaced by a new one, based on Finemet technology. These and other improvements will help to increase the LHC luminosity by a factor of ten. In order to study beam stability in the longitudinal plane simulations have been performed with the CERN BLonD code, using an accurate longitudinal impedance model and a reliable estimation of the longitudinal space charge. Particular attention has been dedicated to the three main features that currently let the beam go stably through the ramp: Double RF operation in bunch-lengthening mode to reduce the transverse space charge tune spread, exploitation of feedback loops to damp dipole oscillations, and controlled longitudinal emittance blow-up. RF phase noise injection has been considered to study if it could complement or substitute the currently used method based on sinusoidal phase modulation.  
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MOPR029 On the Impact of Non-Symplecticity of Space Charge Solvers space-charge, emittance, optics, resonance 146
 
  • M. Titze
    CERN, Geneva, Switzerland
  
  Funding: German Federal Ministry of Education and Research (BMBF)
To guarantee long-term reliability in the predictions of a numerical integrator, it is a well-known requirement that the underlying map has to be symplectic. It is therefore important to examine in detail the impact on emittance growth and noise generation in case this condition is violated. We present a strategy of how to tackle this question and some results obtained for particular PIC and frozen space charge models. 		 
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MOPR030 Simple Models for Beam Loss Near the Half Integer Resonance with Space Charge resonance, space-charge, lattice, coherent-effects 150
 
  • C.M. Warsop, D.J. Adams, B. Jones, B.G. Pine
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  The half integer resonance is often used to define the high intensity limit of medium or low energy hadron rings where transverse space charge is significant. However, the mechanism leading to particle loss as beam approaches this resonance, which thus defines the limit, is not clearly understood. In this paper we explore simple models, based on single particle resonance ideas, to see if they describe useful aspects of motion as observed in simulations and experiments of 2D coasting beams on the ISIS synchrotron. Single particle behaviour is compared to 2D self-consistent models to assess when coherent motion begins to affect the single particle motion, and understand the relevance of coherent and incoherent resonance. Whilst the general problem of 2D resonant loss, with non-stationary distributions and non-linear fields is potentially extremely complicated, here we suggest that for a well-designed machine, where higher order pathological loss effects are avoided, a relatively simple model may give valuable insights into beam behaviour and control.  
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MOPR031 Development of Physics Models of the ISIS Head-Tail Instability impedance, space-charge, synchrotron, acceleration 155
 
  • R.E. Williamson, B. Jones, C.M. Warsop
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  ISIS is the pulsed spallation neutron and muon source at the Rutherford Appleton Laboratory in the UK. Operation centres on a rapid cycling proton synchrotron which accelerates 3·1013 protons per pulse (ppp) from 70 MeV to 800 MeV at 50 Hz, delivering a mean beam power of 0.2 MW. As a high intensity, loss-limited machine, research and development at ISIS is focused on understanding loss mechanisms with a view to improving operational performance and guiding possible upgrade routes. The head-tail instability observed on ISIS is of particular interest as it is currently a main limitation on beam intensity. Good models of impedance are essential for understanding instabilities and to this end, recent beam-based measurements of the effective transverse impedance of the ISIS synchrotron are presented. This paper also presents developments of a new, in-house code to simulate the head-tail instability observed and includes benchmarks against theory and comparisons with experimental results.  
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MOPR033 Beam Acceleration and Transition Crossing in the Fermilab Booster impedance, booster, emittance, timing 160
 
  • V.A. Lebedev, C.M. Bhat, J.-F. Ostiguy
    Fermilab, Batavia, Illinois, USA
  
  To suppress eddy currents, the Fermilab rapid cycling Booster synchrotron has no beam pipe; rather, its combined function dipoles are evacuated, exposing the beam directly to the magnet laminations. This arrangement significantly increases the resistive wall impedance of the dipoles and, in combination with the space charge impedance, substantially complicates longitudinal dynamics at transition. Voltage and accelerating phase profiles in the vicinity of transition are typically empirically optimized to minimize beam loss and emittance growth. In this contribution, we present results of experimental studies of beam acceleration near transition. Using comparisons between observed beam parameters and simulations, we obtain accurate calibrations for the RF program and extract quantitative information about parameters of relevance to the Booster laminated magnets longitudinal impedance model. The results are used to analyze transition crossing in the context of a future 50% increase in beam intensity planned for PIP-II, an upgrade of the Fermilab accelerating complex.  
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MOPL003 Status of the Beam Dynamics Design of the New Post-Stripper DTL for GSI - FAIR DTL, quadrupole, ion, emittance 184
 
  • A. Rubin, D. Daehn, X. Du, L. Groening, M. Kaiser, S. Mickat
    GSI, Darmstadt, Germany
  
  The GSI UNILAC has served as injector for all ion species since 40 years. Its 108 MHz Alvarez DTL providing acceleration from 1.4 MeV/u to 11.4 MeV/u has suffered from material fatigue and has to be replaced by a new section. The design of the new post-stripper DTL is now under development in GSI. An optimized drift tube shape increases the shunt impedance and varying stem orientations mitigate parasitic rf-modes. This contribution is on the beam dynamics layout.  
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MOPL004 Beam Dynamics Simulations and Code Comparison for a New CW RFQ Design rfq, linac, space-charge, focusing 188
 
  • S.M. Polozov, W.A. Barth, T. Kulevoy, S. Yaramyshev
    MEPhI, Moscow, Russia
  • W.A. Barth, S. Yaramyshev
    GSI, Darmstadt, Germany
  • W.A. Barth
    HIM, Mainz, Germany
  • T. Kulevoy
    ITEP, Moscow, Russia
  
  Research and development of CW applications is an important step in RFQ design. The RF potential should be limited by 1.3-1.5 of Kilpatrick criterion for the CW mode. A 2 MeV RFQ is under development for the compact CW research proton accelerator, as well as for planned driver linac* in Russia. The maximum beam current is fixed to10 mA; the operating frequency has been set to 162 MHz. The new RFQ linac design will be presented and beam dynamics simulation results will be discussed. Calculations of beam dynamics are provided using the codes BEAMDULAC (developed at MEPhI for linac design) and DYNAMION. A comparison of the software performance is presented.
* A.Y. Aksentyev, T.V. Kulevoy, S.M. Polozov. Proc. of IPAC’14, pp. 3286-3288. 		 
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MOPL005 The Simulation Study of Beam Dynamics for CSNS Linac During Beam Commissioning emittance, DTL, rfq, linac 192
 
  • Y. Yuan, H.F. Ji, S. Wang
    IHEP, Beijing, People's Republic of China
  • J. Peng
    CSNS, Guangdong Province, People's Republic of China
  
  China Spallation Neutron Source (CSNS) is a high intensity accelerator based facility. Its accelerator consists of an H− injector and a proton Rapid Cycling Synchrotron. The injector includes the front end and linac. The RFQ accelerates the beam to 3MeV, and then the Drift Tube Linac (DTL) accelerates it to 80MeV[1]. An Medium Energy Beam Transport (MEBT) matches RFQ and DTL, and the DTL consists of four tanks. Commissioning of the MEBT and the first DTL tank (DTL1) have been accomplished in the last run. Due to the difference of actual effective length and theoretical effective length of magnets in MEBT and DTL1, in order to compare its impact of beam transport, this paper takes a beam dynamics simulation on beam transport in MEBT and DTL1 with IMPACT-Z code[2]. Meanwhile, the transport of beam with different emittance in MEBT and DTL1 is studied because of the large emittance at RFQ exit. All the simulation includes magnet error and RF error.  
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MOPL006 Beam Dynamics Study of C-Ads Injector-I With Developing P-Topo Code rfq, space-charge, emittance, lattice 195
 
  • Zh.C. Liu, C. Li, Q. Qin, F. Yan, Y.L. Zhao
    IHEP, Beijing, People's Republic of China
  
  A parallelized, time-dependent 3D particle simulation code is under developing to study the high-intensity beam dynamics in linear accelerators. The self-consistent space charge effect is taken into account with the Particle-In-Cell (PIC) method. In this paper, the structure of program and the parallel strategy are demonstrated. Then, we show the results of code verification and benchmarking. It is proved that the solvers in P-TOPO code and parallel strategy are reliable and efficient. Finally, the beam dynamics simulation of C-ADS Injector-I at IHEP are launched with P-TOPO and other codes. The possible reasons for the differences between results given by separated codes are also proposed.  
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MOPL007 Beam Steering Studies for the Superconducting Linac of the RAON Accelerator quadrupole, linac, GUI, lattice 199
 
  • H. Jin, J.-H. Jang, D. Jeon
    IBS, Daejeon, Republic of Korea
  
  The RAON accelerator of Rare Isotope Science Project (RISP) has been developed to accelerate various kinds of stable ion beams and rare isotope beams for a wide range of science experiments. In the RAON accelerator, the superconducting linac (SCL) will be installed for the acceleration of the beams and it is composed of tens of cryomodules which include superconducting radio frequency cavities. Between two cryomodules, there is a warm section and two quadrupoles are located in the warm section with a beam diagnostics box in between. Also, in this warm section, one horizontal corrector and one beam position monitor (BPM) are mounted inside of first quadrupole, and one vertical corrector is located inside of second quadrupole for the beam steering. With these correctors and BPMs, the beam steering studies are carried out as varying the number of correctors and BPMs in the SCL of the RAON accelerator and the results are presented.  
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MOPL015 Effect of Beam Losses on Wire Scanner Scintillator Readout, Hypothesis and Preliminary Results detector, linac, quadrupole, beam-losses 216
 
  • B. Cheymol
    ESS, Lund, Sweden
  
  In hadron accelerators, the characterization of the beam transverse halo can lead to a better understanding of the beam dynamics and ultimately to a reduction of the beam losses. Unfortunately the effect of losses on beam instrumentation implies a reduction of the instrument sensitivity due to the background noise. In this paper, we will discuss the effect of losses on the wire scanner scintillator foreseen for the ESS linac, in particular the different hypothesis for the input will be described and preliminary results will be presented.  
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MOPL016 Effects of Energy Deposition Models and Conductive Cooling on Wire Scanner Thermal Load, Analytical and Finite Element Analysis Approach radiation, linac, operation, insertion 221
 
  • B. Cheymol
    ESS, Lund, Sweden
  
  One of the main limitations of the wire scanner in high intensity linac is the inability of the wire to survive at high duty cycle. For the commissioning of such machines, duty cycle must be reduced to preserve interceptive devices. A good thermal model of the wire is needed to insure a safe operation of the wire scanner and set the limits of acceptable beam duty cycle. In this paper, we will discuss the influence of the energy deposition model and the efficiency of conductive cooling on the wire temperature, based on the ESS beam parameters.  
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MOPL017 High Power and High Duty Cycle Slit and Grid System for Hadron Accelerator Commissioning emittance, scattering, rfq, DTL 226
 
  • B. Cheymol, A. Ponton
    ESS, Lund, Sweden
  
  Transverse emittance is one of the key measurements to be performed during the commissioning of the low energy sections of an hadron linac. The good knowledge of the beam transverse phase space allows a safe and efficient operation of the machines by using the results of the measurement for beam dynamic simulations. In this paper we will discuss the accuracy and the limits of the transverse emittance measurement performed with the slit-grid method based on the ESS beam parameters at the RFQ (beam energy equal to 3.62 MeV) and DTL tank 1 (beam energy equal to 21 MeV) output.  
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MOPL018 Scintillator Detectors for the ESS High Energy Wire Scanner detector, radiation, photon, linac 232
 
  • B. Cheymol
    ESS, Lund, Sweden
  
  In the ESS linac, during commissioning and restart phase, wire scanner will be used intensively to characterize the transverse beam profiles. At low energy, the mode of detection is based on Secondary Emission (SE), while at energies above 200 MeV, the primary mode of detection will be the measurement of the hadronic shower created in the thin wire. In this paper we will present the design and the output signal estimation of the shower detector, based on inorganic crystal and silicon photodetector.  
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MOPL021 Fermilab Booster Transition Crossing Simulations and Beam Studies booster, quadrupole, proton, space-charge 242
 
  • C.M. Bhat, C.-Y. Tan
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy
The Fermiab Booster accelerates beam from 400 MeV to 8 GeV at 15 Hz. In the PIP (Proton Improvement Plan) era, it is required that Booster deliver 4.2·1012 protons per pulse to extraction. One of the obstacles for providing quality beam to the users is the longitudinal quadrupole oscillation that the beam suffers from right after transition. Although this oscillation is well taken care of with quadrupole dampers, it is important to understand the source of these oscillation in light of the PIP II requirements that require 6.5·1012 protons per pulse at extraction. This paper explores the results from computer simulations, machine studies and solutions to prevent the quadrupole oscillation after transition.
Author would like to thank S. Chaurize, C. Drennan, W. Pellico, K. Seiya, T. Sullivan and K. Triplett 		 
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TUAM2X01 Measurement and Interpretation of Transverse Beam Instabilities in the CERN Large Hadron Collider (LHC) and Extrapolations to HL-LHC octupole, coupling, electron, injection 254
 
  • E. Métral, G. Arduini, N. Biancacci, X. Buffat, L.R. Carver, G. Iadarola, K.S.B. Li, T. Pieloni, A. Romano, G. Rumolo, B. Salvant, M. Schenk, C. Tambasco
    CERN, Geneva, Switzerland
  • J. Barranco
    EPFL, Lausanne, Switzerland
  
  Since the first transverse instability observed in 2010, many studies have been performed on both measurement and simulation sides and several lessons have been learned. In a machine like the LHC, not only all the mechanisms have to be understood separately, but the possible interplays between the different phenomena need to be analyzed in detail, including the beam-coupling impedance (with in particular all the necessary collimators to protect the machine but also new equipment such as crab cavities for HL-LHC), linear and nonlinear chromaticity, Landau octupoles (and other intrinsic nonlinearities), transverse damper, space charge, beam-beam (long-range and head-on), electron cloud, linear coupling strength, tune separation between the transverse planes, tune split between the two beams, transverse beam separation between the two beams, etc. This paper reviews all the transverse beam instabilities observed and simulated so far, the mitigation measures which have been put in place, the remaining questions and challenges and some recommendations for the future.  
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TUAM3X01 Identification and Reduction of the CERN SPS Impedance impedance, emittance, flattop, vacuum 260
 
  • E.N. Shaposhnikova, T. Argyropoulos, T. Bohl, A. Lasheen, J. Repond, H. Timko
    CERN, Geneva, Switzerland
  
  The first SPS impedance reduction programme has been completed in 2001, preparing the ring for its role as an injector of the LHC. This action has eliminated microwave instability on the SPS flat bottom and later nominal beam could be delivered to the LHC. The High Luminosity (HL-) LHC project is based on beam with twice higher intensity than the nominal one. One of the important SPS intensity limitations are longitudinal instabilities with minimum threshold reached on the 450 GeV flat top. In this paper the work which was carried on to identify the impedance sources driving these instabilities is described together with the next campaign of the SPS impedance reduction planned by the LHC Injector Upgrade (LIU) project. The present knowledge of the SPS transverse impedance is also presented.  
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TUAM4X01 Electron Cloud in the CERN Accelerator Complex operation, emittance, electron, quadrupole 266
 
  • G. Rumolo, H. Bartosik, E. Belli, G. Iadarola, K.S.B. Li, L. Mether, A. Romano
    CERN, Geneva, Switzerland
  • M. Schenk
    EPFL, Lausanne, Switzerland
  
  Operation with closely spaced bunched beams causes the build up of an Electron Cloud (EC) in both the LHC and the two last synchrotrons of its injector chain (PS and SPS). Pressure rise and beam instabilities are observed at the PS during the last stage of preparation of the LHC beams. The SPS was affected by coherent and incoherent emittance growth along the LHC bunch train over many years, before scrubbing has finally suppressed the EC in a large fraction of the machine. When the LHC started regular operation with 50 ns beams in 2011, EC phenomena appeared in the arcs during the early phases, and in the interaction regions with two beams all along the run. Operation with 25 ns beams (late 2012 and 2015), which is nominal for LHC, has been hampered by EC induced high heat load in the cold arcs, bunch dependent emittance growth and degraded beam lifetime. Dedicated and parasitic machine scrubbing is presently the weapon used at the LHC to combat EC in this mode of operation. This talk summarises the EC experience in the CERN machines (PS, SPS, LHC) and highlight the dangers for future operation with more intense beams as well as the strategies to mitigate or suppress the effect.  
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TUAM6X01 First Analysis of the Space Charge Effects on a Third Order Coupled Resonance resonance, space-charge, emittance, synchrotron 278
 
  • G. Franchetti
    GSI, Darmstadt, Germany
  • S.S. Gilardoni, A. Huschauer, F. Schmidt, R. Wasef
    CERN, Geneva, Switzerland
  
  The effect of space charge on bunches stored for long term in a nonlinear lattice can be severe for beam survival. This may be the case in projects as SIS100 at GSI or LIU at CERN. In 2012, for the first time, the effect of space charge on a normal third order coupled resonance was investigated at the CERN-PS. The experimental results have highlighted an unprecedented asymmetric beam response: in the vertical plane the beam exhibits a thick halo, while the horizontal profile has only core growth. The quest for explaining these results requires a journey through the 4 dimensional dynamics of the coupled resonance investigating the fixed-lines, and requires a detailed code-experiment benchmarking also including beam profile benchmarking. This proceeding gives a short summary of the experimental results of the 2012 PS measurements, and address an interpretation based on the dynamics the fixed-lines.  
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TUAM7X01 Intensity Effects in the Formation of Stable Islands in Phase Space During the Multi-Turn Extraction Process at the CERN PS space-charge, vacuum, closed-orbit, extraction 283
 
  • S. Machida
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • S.S. Gilardoni, M. Giovannozzi, S. Hirlaender, A. Huschauer
    CERN, Geneva, Switzerland
  • C.R. Prior
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  The CERN PS utilises a multi-turn extraction (MTE) scheme to stretch the beam pulse length to optimise the filling process of the SPS. MTE is a novel technique to split a beam in transverse phase space into nonlinear stable islands. The recent experimental results indicate that the positions of the islands depend on the total beam intensity. Particle simulations have been performed to understand the detailed mechanism of the intensity dependence. The analysis carried out so far suggests space charge effects through image charges and image currents on the vacuum chamber and the magnets’ iron cores dominate the observed behaviour. In this talk, the latest analysis with realistic modelling of the beam environment is discussed and it is shown how this further improves the understanding of intensity effects in MTE.  
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TUPM3X01 R&D on Beam Injection and Bunching Schemes in the Fermilab Booster booster, injection, emittance, linac 293
 
  • C.M. Bhat
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy
Fermilab is committed to upgrade its accelerator complex towards the intensity frontier by making a substantial increase in the average beam power delivered to the neutrino and muon programs pursuing HEP research in the lepton sector. Proton Improvement Plan (PIP) enables us to provide 700 kW beam power by the end of this year. By the middle of next decade, the foreseen PIP–II replaces the existing LINAC, a 400 MeV injector to the Booster, by an 800 MeV superconducting LINAC with beam power increased by >50%. In any case, the Fermilab Booster, an 8 GeV injector to the MI, is going to play a very significant role for the next two decades. In this context, we have recently developed an innovative beam injection scheme for the Booster called "early injection scheme" and put into operation. This novel scheme has a potential to increase the Booster beam intensity from the PIP design goal by ~40%. Some benefits of the scheme have already been seen so far. In this talk, I will present, principle of the scheme, results from beam experiments, current status and future plans for the early beam injection scheme. This scheme fits well with the current and future programs at Fermilab.
Author would like to thank S. Chaurize, C. Drennan, F. Garcia, B. Hendrick, W. Pellico, K. Seiya, T. Sullivan, K. Triplett and A. Waller, 		 
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TUPM3Y01 Operational Experience and Future Plans at ISIS operation, injection, acceleration, proton 333
 
  • D.J. Adams
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • I.S.K. Gardner, B. Jones, A.H. Kershaw, A.P. Letchford, R.J. Mathieson, A. Pertica, B.G. Pine, A. Seville, H. V. Smith, C.M. Warsop, R.E. Williamson, M. Wright
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  The ISIS spallation neutron and muon source has been in operation since 1984. The accelerator complex consists of an H− ion source, 665 keV RFQ, 70 MeV linac, 800 MeV proton synchrotron and associated beam transfer lines. The facility currently delivers ~2.8·1013 protons per pulse (ppp) at 50 Hz, which is shared between two target stations. High intensity performance and operation are dominated by the need to minimise and control beam loss, which is key to sustainable machine operation, allowing essential hands on maintenance. The facility has had several upgrades including an RFQ, ring Second Harmonic RF system, key developments of diagnostics and instrumentation required for improving beam control and a Second Target station. Upgrades being installed, or expected in the near future, include: a ring damping system, a new injector MEBT with fast injection chopper and an upgraded 50 Hz target. Operational experience of ISIS and the impacts of its past and future upgrades are discussed. Ideas for major upgrades to ISIS are briefly reviewed, as are the underlying R&D projects.  
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TUPM4Y01 IFMIF-EVEDA RFQ, Measurement of Beam Input Conditions and Preparation to Beam Commissioning rfq, emittance, solenoid, space-charge 338
 
  • M. Comunian, L. Bellan, E. Fagotti, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  • L. Bellan
    Univ. degli Studi di Padova, Padova, Italy
  
  The commissioning phase of the IFMIF-EVEDA RFQ requires a complete beam characterization with simulations and measurements of the beam input from the IFMIF-EVEDA ion source and LEBT, in order to reach the RFQ input beam parameters. In this article the simulations of source LEBT RFQ will be reported with the corresponding set of measurements done on the Ion source and LEBT.  
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WEAM1X01 Code Bench-Marking for Long-Term Tracking and Adaptive Algorithms emittance, space-charge, resonance, experiment 357
 
  • F. Schmidt, H. Bartosik, A. Huschauer, A. Oeftiger, M. Titze
    CERN, Geneva, Switzerland
  • Y.I. Alexahin, J.F. Amundson, V.V. Kapin, E.G. Stern
    Fermilab, Batavia, Illinois, USA
  • G. Franchetti
    GSI, Darmstadt, Germany
  • J.A. Holmes
    ORNL, Oak Ridge, Tennessee, USA
  
  At CERN we have ramped up a program to investigate space charge effects in the LHC pre-injectors with high brightness beams and long storage times. This in view of the LIU upgrade project for these accelerators. These studies require massive simulation over large number of turns. To this end we have been looking at all available codes and started collaborations on code development with several laboratories: pyORBIT from SNS, SYNERGIA from Fermilab, MICROMAP from GSI and our in-house MAD-X code with an space charge upgrade. We have agreed with our collaborators to bench-mark all these codes in the framework of the GSI bench-marking suite, in particular the main types of frozen space charge and PIC codes are being tested. We also include a study on the subclass of purely frozen and the adaptive frozen modes both part of MAD-X in comparison with the purely frozen MICROMAP code. Last, we will report on CERN's code development effort to understand and eventually overcome the noise issue in PIC codes.
J. Coupard et al., ‘‘LHC Injectors Upgrade,
Technical Design Report, Vol. I: Protons'', LIU Technical Design
Report (TDR), CERN-ACC-2014-0337. 		 
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WEAM3X01 Code Development for Collective Effects electron, interface, synchrotron, space-charge 362
 
  • K.S.B. Li, H. Bartosik, G. Iadarola, A. Oeftiger, A. Passarelli, A. Romano, G. Rumolo, M. Schenk
    CERN, Geneva, Switzerland
  • S. Hegglin
    ETH, Zurich, Switzerland
  • A. Oeftiger, M. Schenk
    EPFL, Lausanne, Switzerland
  
  The presentation will cover approaches and strategies of modeling and implementing collective effects in modern simulation codes. We will review some of the general approaches to numerically model collective beam dynamics in circular accelerators. We will then look into modern ways of implementing collective effects with a focus on plainness, modularity and flexibility, using the example of the PyHEADTAIL framework, and highlight some of the advantages and drawbacks emerging from this method. To ameliorate one of the main drawbacks, namely a potential loss of performance compared to the classical fully compiled codes, several options for speed improvements will be mentioned and discussed. Finally some examples and application will be shown together with future plans and perspectives.  
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WEAM4X01 Numerical Modeling of Fast Beam Ion Instabilities ion, electron, damping, linac 368
 
  • L. Mether, G. Iadarola, G. Rumolo
    CERN, Geneva, Switzerland
  
  The fast beam ion instability may pose a risk to the operation of future electron accelerators with beams of high intensity and small emittances, including several structures of the proposed CLIC accelerator complex. Numerical models can be used to identify necessary vacuum specifications to suppress the instability, as well as requirements for a possible feedback system. Vacuum requirements imposed by the instability have previously been estimated for linear CLIC structures, using the strong-strong macroparticle simulation tool FASTION. Currently, efforts are being made to improve the simulation tools, and allow for equivalent studies of circular structures, such as the CLIC damping rings, on a multi-turn scale. In this contribution, we review the recent code developments, and present first simulation results.  
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WEPM7X01 The Application of the Optimization Algorithm in the Collimation System for CSNS/RCS collimation, acceleration, space-charge, emittance 397
 
  • H.F. Ji, M.Y. Huang, Y. Jiao, N. Wang, S. Wang, S.Y. Xu
    IHEP, Beijing, People's Republic of China
  
  The robust conjugate direction search (RCDS) method, which is developed by X. Huang from the SLAC National Accelerator Laboratory, has high tolerance against noise in beam experiments and thus can find an optimal solution effectively and efficiently. In this paper, the RCDS method is used to optimize the beam collimation system for Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS). A two-stage beam collimation system was designed to localize the beam loss in the collimation section in CSNS/RCS. The parameters of secondary collimators are optimized with RCDS algorithm based on detailed tracking with the ORBIT program for a better performance of the collimation system. The study presents a way to quickly find an optimal parameter combination of the secondary collimators for a machine model for preparation for CSNS/RCS commissioning.  
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WEAM5Y01 Analyzing and Matching of Mixed High Intensity Highly Charged Ion Beams ion, solenoid, space-charge, ion-source 422
 
  • X.H. Zhang, C. Qian, L.T. Sun, Y. Yang, X. Yin, Y.J. Yuan, H.W. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
  
  Funding: Work supported by the National Natural Science Foundation of China (No. 11575265, 11427904) and the “973” Program of China (No. 2014CB845501).
Electron cyclotron resonance (ECR) ion sources are widely used in heavy ion accelerators for their advantages in producing high quality intense beams of highly charged ions. However, it exists challenges in the design of the Q/A selection systems for mixed high intensity ion beams to reach sufficient Q/A resolution while controlling the beam emittance growth. Moreover, as the emittance of beam from ECR ion sources is coupled, the matching of phase space to post accelerator, for a wide range of ion beam species with different intensities, should be carefully studied. In this paper, the simulation and experimental results of the Q/A selection system at the LECR4 platform are shown. The formation of hollow cross section heavy ion beam at the end of the Q/A selector is revealed. A reasonable interpretation has been proposed, a modified design of the Q/A selection system has been committed for HIRFL-SSC linac injector. The features of the new design including beam simulations and experiment results are also presented. 		 
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WEAM7Y01 The Beam Delivery System of the European Spallation Source target, multipole, proton, controls 427
 
  • H.D. Thomsen
    Aarhus University, Aarhus, Denmark
  • S.P. Møller
    ISA, Aarhus, Denmark
  
  The European Spallation Source (ESS) will apply a fast beam scanning system to redistribute the proton beam transversely across the spallation target surface. The system operates at sweep frequencies of tens of kHz and efficiently evens out the time-averaged beam intensity within a nominal beam footprint, thus reducing the level of beam-induced material damage. A modular design approach divides the raster action in each direction across 4 independent magnet-supply systems to distribute the magnetic load, ease the peak output power per modulator, and in general reduce the impact of single points of failure. The state of the magnet design and power supply topology will be discussed.  
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WEPM4Y01 HPSim - Advanced Online Modeling for Proton Linacs linac, controls, DTL, GPU 444
 
  • L. Rybarcyk
    LANL, Los Alamos, New Mexico, USA
  
  High-power proton linacs seek to operate with low and stable losses. This aspect is carefully evaluated with multi-particle beam dynamics codes during the design stage. However, it is just as important to evaluate the performance of the actual operating linac, which is typically more tedious and complicated when using these same design codes. To improve this situation, we have developed a high-performance, multi-particle online modeling tool, HPSim, with the goal of providing near real-time simulation results for our 800-MeV proton linac at Los Alamos. This presentation will cover the motivation, code features, benefits and applications.  
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WEPM5Y01 H− Beam Dynamics Study of a LEBT in XiPAF Project with the WARP PIC Code space-charge, ion, rfq, proton 449
 
  • R. Ruo, L. Du, T.B. Du, X. Guan, C.-X. Tang, X.W. Wang, Q.Z. Xing, H.Y. Zhang, Q.Z. Zhang
    TUB, Beijing, People's Republic of China
  • Y. He, J. Li
    NUCTECH, Beijing, People's Republic of China
  
  The 7 MeV H− linac injector of Xi‘an Proton Application Facility (XiPAF) is composed of an ECR ion source, a Low Energy Beam Transport line (LEBT), a Radio Frequency Quadrupole accelerator (RFQ) and a Drift Tube Linac (DTL). The 1.7 m-long LEBT is used for matching a 40 μs pulse width 6 mA peak current beam to the entrance of the RFQ accelerator. The peak current and pulse-width of the 50 keV H− beam extracted from the ion source is 10 mA and 1 ms respectively. In the LEBT, an adjustable aperture is used for scraping the peak current of the beam to 6 mA, and an electric chopper is used for chopping the beam pulse width to 40 μs. These elements make the space charge compensation problem more complicated. A careful simulation of the space charge compensation problem of the H− beam has been done by considering the beam particles interacting with the residual gas with the help of WARP PIC code. To achieve the requirements of the LEBT in XiPAF, the type and pressure of the residual gas is given according to the simulation results.  
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WEPM6Y01 Study on Space Charge Compensation of Low Energy High Intensity Ion Beam in Peking University space-charge, ion, experiment, ion-source 453
 
  • S.X. Peng, J.E. Chen, Z.Y. Guo, H.T. Ren, J.M. Wen, W.B. Wu, Y. Xu, A.L. Zhang, J.F. Zhang, T. Zhang
    PKU, Beijing, People's Republic of China
  • J.E. Chen
    Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
  • H.T. Ren
    FRIB, East Lansing, Michigan, USA
  • A.L. Zhang
    University of Chinese Academy of Sciences, Beijing, People's Republic of China
  
  To better understand the space charge compensation processes in low energy high intensity beam transportation, numerical study and experimental simulation on H+ beam and H− beam were carried out at Peking University (PKU). The numerical simulation is done with a PIC-MCC model [1] whose computing framework was done with the 3D MATLAB PIC code bender [2], and the impacts among particles were done with Monte Carlo collision via null-collision method [3]. Issues, such as beam loss caused by collisions in H+, H− beam and ion-electron instability related to decompensation and overcompensation in H− beam, are carefully treated in this model. The experiments were performed on PKU ion source test bench. Compensation gases were injected directly into the beam transportation region to modify the space charge compensation degree. The results obtained during the experiment are agree well with the numerical simulation ones for both H+ beam [1] and H− beam [4]. Details will be presented in this paper.  
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WEPM8Y01 Simulation of Space-Charge Compensation of a Low-Energy Proton Beam in a Drift Section electron, emittance, ion, proton 458
 
  • D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte
    IAP, Frankfurt am Main, Germany
  
  Space-charge compensation provided by the accumulation of particles of opposing charge in the beam potential is an important effect occuring in magnetostatic low energy beam transport sections of high-intensity accelerators. An improved understanding of its effects might provide valuable input for the design of these beam lines. One approach to model the compensation process are Particle-in-Cell (PIC) simulations including residual gas ionisation. In simulations of a drifting proton beam, using the PIC code bender [1], some features of thermal equilibrium for the compensation electrons were found. This makes it possible to predict their spatial distribution using the Poisson-Boltzmann equation and thus the influence on beam transport. In this contribution, we will provide a comparison between the PIC simulations and the model as well as some ideas concerning the source of the (partial) thermalization.
[1] D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner - The Particle-in-Cell Code Bender and Its Application to Non-Relativistic Beam Transport, WEO4LR02, Proc. of HB2014 		 
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THPM7X01 Use of RF Quadrupole Structures to Enhance Stability in Accelerator Rings quadrupole, betatron, octupole, synchrotron 505
 
  • M. Schenk, A. Grudiev, K.S.B. Li, K. Papke
    CERN, Geneva, Switzerland
  
  The beams required for the high luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN call for efficient mechanisms to suppress transverse collective instabilities. In addition to octupole magnets installed for the purpose of Landau damping, we propose to use radio frequency (rf) quadrupole structures to considerably enhance the aforementioned stabilising effect. By means of the PyHEADTAIL macroparticle tracking code, the stabilising mechanism introduced by an rf quadrupole is studied and discussed. As a specific example, the performance of an rf quadrupole system in presence of magnetic octupoles is demonstrated for HL-LHC. Furthermore, potential performance limitations such as the excitation of synchro-betatron resonances are pointed out. Finally, efforts towards possible measurements with the CERN Super Proton Synchrotron (SPS) are discussed aiming at studying the underlying stabilising mechanisms experimentally.  
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THPM8X01 Early Tests and Simulation of Quasi-Integrable Octupole Lattices at the University of Maryland Electron Ring octupole, lattice, distributed, quadrupole 511
 
  • K.J. Ruisard, H. Baumgartner, B. Beaudoin, I. Haber, T.W. Koeth, D.B. Matthew
    UMD, College Park, Maryland, USA
  
  Funding: Work and travel supported by NSF GRFP, NSF Accelerator Science Program, DOE-HEP and UMD Graduate School ICSSA award.
Nonlinear quasi-integrable optics is a promising development on the horizon of high-intensity ring design. Large amplitude-dependent tune spreads, driven by strong nonlinear magnet inserts, lead to decoherence from incoherent tune resonances. This reduces intensity-driven beam loss while quasi-integrability ensures contained orbits. The experimental program at the University of Maryland Electron Ring (UMER) will explore the performance of a strong octupole lattice at a range of operating points. Early measurements use a distributed octupole lattice, consisting of several small octupole inserts. We vary lattice tune to change the quasi-integrable condition as well as probe behavior near different resonant conditions. Simulation results show there should be invariant conservation under carefully chosen conditions. We discuss the effect of steering errors on the lattice performance and on-going efforts to reduce these errors. We also discuss plans for a single-channel insert. 		 
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THPM9X01 Space Charge Effects and Mitigation in the CERN PS Booster, in View of the Upgrade injection, emittance, booster, space-charge 517
 
  • E. Benedetto, M. Cieslak-Kowalska, V. Forte, F. Schmidt
    CERN, Geneva, Switzerland
  • M. Cieslak-Kowalska
    EPFL, Lausanne, Switzerland
  • V. Forte
    Université Blaise Pascal, Clermont-Ferrand, France
  
  The CERN PS Booster (PSB) is presently running with a space-charge tune spread larger than 0.5 at injection. Since the High Luminosity LHC (HL-LHC) will require beams with twice the intensity and brightness of today, the LHC Injector Upgrade (LIU) Project is putting in place an upgrade program for all the injector chain and, in particular, it relies on the important assumption that the PS Booster can successfully produce these beams after the implementation of the 160 MeV H− injection from Linac4. This contribution describes the studies (measurements and simulations) that have been carried out to confirm that the PSB can indeed perform as needed in terms of beam brightness for the future HL-LHC runs. The importance of the mitigation measures already in place, such as the correction of the half-integer line, and the effects of non-linear resonances on the beam are also discussed.  
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THPM10X01 Stripline Beam Position Monitors With Improved Frequency Response and Their Coupling Impedances impedance, coupling, network, electron 523
 
  • Y. Shobuda
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • Y.H. Chin, K. Takata
    KEK, Ibaraki, Japan
  • K.G. Nakamura
    Kyoto University, Kyoto, Japan
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  
  In J-PARC Main Ring, transverse intra-bunch oscillations have been observed during the injection and at the onset of acceleration. Up to now, the beam instability is suppressed by the intra-bunch feedback system, where the stripline beam position monitors operate at 108.8 MHz. However, there is a concern that electron cloud instabilities may appear and limit the beam current at future higher power operations. For the case, we have developed a wider-band (several GHz) beam position monitor by deforming the electrode shapes. The modification of the electrode can be done not to enhance the beam coupling impedance. For the typical electrode shapes, we show the coupling impedances as well as the frequency responses of the electrodes.  
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THAM2Y01 Measurements of Beam Pulse Induced Mechanical Strain Inside the SNS* Target Module target, radiation, experiment, proton 532
 
  • W. Blokland, Y. Liu, B.W. Riemer, M. Wendel, D.E. Winder
    ORNL, Oak Ridge, Tennessee, USA
  • M.J. Dayton
    ORNL RAD, Oak Ridge, Tennessee, USA
  
  Funding: * ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
Because several of the SNS targets have had a shorter lifetime than desired, a new target has been instrumented with strain sensors to further our understanding of the proton beam’s mechanical impact. The high radiation and electrically noisy environment led us to pick multi-mode fiber optical strain sensors over other types of strain sensors. Special care was taken to minimize the impact of the sensors on the target’s lifetime. We also placed accelerometers outside the target to try correlating the outside measurements with the internal measurements. Remote manipulators performed the final part of the installation, as even residual radiation is too high for humans to come close to the target’s final location. The initial set of optical sensors on the first instrumented target lasted just long enough to give us measurements from different proton beam intensities. A second set of more rad-hard sensors, installed in the following target, lasted much longer, to give us considerably more data. We are developing our own rad-hard, single-mode fiber optic sensors. This paper describes the design, installation, data-acquisition system, the results of the strain sensors, and future plans. 		 
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THAM6Y01 Simulations and Detector Technologies for the Beam Loss Monitoring System at the ESS Linac detector, linac, DTL, neutron 553
 
  • I. Dolenc Kittelmann, T.J. Shea
    ESS, Lund, Sweden
  
  The European Spallation Source (ESS), which is currently under construction, will be a neutron source based on 5 MW, 2 GeV superconducting proton linac. Among other beam instrumentation systems, this high intensity linac requires a Beam Loss Monitoring (BLM) system. An important function of the BLM system is to protect the linac from beam-induced damage by detecting unacceptably high beam loss and promptly inhibiting beam production. In addition to protection functionality, the system is expected to provide the means to monitor the beam losses during all modes of operation with the aim to avoid excessive machine activation. This paper focuses on the plans and recent results of the beam loss studies based on Monte Carlo simulations in order to refine the ESS BLM detector requirements by providing the estimations on expected particle fluxes and their spectra at detector locations. Furthermore, the planned detector technologies for the ESS BLM system will be presented.  
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THPM7Y01 A New RFQ Model and Symplectic Multi-Particle Tracking in the IMPACT Code Suite rfq, space-charge, proton, emittance 562
 
  • J. Qiang
    LBNL, Berkeley, California, USA
  • L. Li, Z. Wang
    PKU, Beijing, People's Republic of China
  
  The IMPACT code suite is a self-consistent parallel three-dimensional beam dynamics simulation toolbox that combines the magnetic optics method and the parallel particle-in-cell method. It has been widely used to study high intensity/high brightness beams in many accelerators. In this paper, we will report on recent improvements to the code such as the capability to model RFQ in time domain and symplectic multi-particle tracking with a gridless spectral solver for space-charge simulation.  
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FRAM2P01 Summary WG-A space-charge, resonance, electron, experiment 575
 
  • W. Fischer
    BNL, Upton, Long Island, New York, USA
  • Y.H. Chin
    KEK, Ibaraki, Japan
  • G. Franchetti
    GSI, Darmstadt, Germany
  
  Friday Summary  
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