ICAP2018 - Classification: D-1 Beam Dynamics Simulations

Paper	Title	Page
SAPLG01	Advances in Simulation of High Brightness/High Intensity Beams	1
	J. Qiang LBNL, Berkeley, California, USA
	High brightness/high intensity beams play an important role in accelerator based applications by driving x-ray free electron laser (FEL) radiation, producing spallation neutrons and neutrinos, and generating new particles in high energy colliders. In this paper, we report on recent advances in modeling the high brightness electron beam with application to the next generation FEL light sources and in modeling space-charge effects in high intensity proton accelerators.
	Slides SAPLG01 [3.914 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SAPLG01
About •	paper received ※ 02 November 2018 paper accepted ※ 19 November 2018 issue date ※ 26 January 2019
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SAPAG02	Beam Dynamics Simulations and Challenges for the FAIR SIS100 Synchrotron
	O. Boine-Frankenheim, V. Chetvertkova, V. Kornilov, S. Sorge GSI, Darmstadt, Germany
	The SIS100 synchrotron is the central accelerator of the upcoming FAIR project at GSI, Darmstadt, Germany. The major challenges for the design studies and the later operation are related to high-intensity, low beam loss operation for a wide range of ion species and charge states, for different operational cycles and extraction schemes. We focus our simulation studies on the long (up to 1 s) accumulation plateau and on the final bunch compression before extraction. During accumulation emittance growth and beam loss due to transverse space charge in combination with the magnet field errors has to be well controlled. We use different simulation approaches with frozen and self-consistent "symplectic" space charge solvers to identify optimum working point areas, including realistic field error models for the superconducting, superferric SIS100 dipole and quadrupole magnets.
	Slides SAPAG02 [1.887 MB]
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SUPAF02	Beam Alignment Simulation on the Beamline of a Proton Therapy Facility
	X. Liu, Q.S. Chen, G. Feng, B. Qin HUST, Wuhan, People’s Republic of China
	Proton therapy is now recognized as one of the most effective radiation therapy methods for cancers. A proton therapy facility with multiple gantry treatment rooms is under development in HUST (Huazhong University of Science and Technology). Misalignments of magnets and beam diagnostics instruments induce the offset of the beam trajectory, which will influence the clinical therapeutic effect. This paper describes the beam alignment simulations based on response matrix and this technology is applied to the design of the HUST-PTF beamline. To perform this study, we use the simulation code ELEGANT, and utilize the global correction method. By optimizing the layout of correctors and beam position monitors, we completed the beam correction calculation. The results show that the accuracy of center beam trajectory in the iso-center is better than 0.5 mm, meeting physical and clinical requirements.
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SUPAF06	Simulations of Coherent Electron Cooling With Free Electron Laser Amplifier and Plasma-Cascade Micro-Bunching Amplifier	52
	J. Ma, V. Litvinenko, G. Wang BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA
	SPACE is a parallel, relativistic 3D electromagnetic Particle-in-Cell (PIC) code used for simulations of beam dynamics and interactions. An electrostatic module has been developed with the implementation of Adaptive Particle-in-Cloud method. Simulations performed by SPACE are capable of various beam distribution, different types of boundary conditions and flexible beam line, as well as sufficient data processing routines for data analysis and visualization. Code SPACE has been used in the simulation studies of coherent electron cooling experiment based on two types of amplifiers, the free electron laser (FEL) amplifier and the plasma-cascade micro-bunching amplifier.
	Slides SUPAF06 [1.260 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF06
About •	paper received ※ 15 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019
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SUPAF09	Sparse Grid Particle-in-Cell Scheme for Noise Reduction in Beam Simulations	71
	A.J. Cerfon Courant Institute of Mathematical Sciences, New York University, New York, USA L.F. Ricketson LLNL, Livermore, California, USA
	The complexity of standard solvers grows exponentially with the number of dimensions of the underlying equations. This issue is particularly acute for continuum solvers, which need to discretize the six-dimensional phase-space distribution function, and whose run times are consequently large even for a moderate number of grid points for each dimension. Particle-in-Cell (PIC) schemes are a popular alternate approach to continuum methods, because they only discretize the three-dimensional physical space and are therefore less subject to the curse of dimensionality. Even if so, PIC solvers still have large run times, because of the statistical error which is inherent to particle methods and which decays slowly with the number of particles per cell. In this talk, we will present a new scheme to address the curse of dimensionality and at the same time reduce the numerical noise of PIC simulations. Our PIC scheme is inspired by the sparse grids combination technique, a method invented to reduce grid based error when solving high dimensional partial differential equations [1]. The technique, when applied to the PIC method, has two benefits: 1) it almost eliminates the dependence of the grid based error on dimensionality, just like in a standard sparse grids application; 2) it lowers the statistical error significantly, because the sparse grids have larger cells, and thus a larger number of particles per cell for a given total number of particles. We will analyze the performance of our scheme for standard test problems in beam physics. We will demonstrate remarkable speed up for a certain class of problems, and less impressive performance for others. The latter will allow us to identify the limitations of our scheme and explore ideas to address them. [1] Griebel M et al. 1990 A combination technique for the solution of sparse grid problems Iterative Methods in Linear Algebra ed R Bequwens and P de Groen (Amsterdam: Elsevier) pp 263-81
	Slides SUPAF09 [1.848 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF09
About •	paper received ※ 19 October 2018 paper accepted ※ 19 November 2018 issue date ※ 26 January 2019
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SUPAF10	Reconstruction of Particle Distributions at RFQ Exit at SNS Beam Test Facility	76
	Z.L. Zhang ORNL RAD, Oak Ridge, Tennessee, USA A.V. Aleksandrov, S.M. Cousineau ORNL, Oak Ridge, Tennessee, USA
	Fluctuations of beam parameters and uncertainties of quadrupole gradients during measurements have effects on the reconstruction of initial particle distributions. To evaluate these effects, the concept of a distribution discrepancy is proposed. Results suggest effects of fluctuations of beam parameters are small, while uncertainties of quadrupole gradients are the main factors that affect the reconstructed distributions. By comparing the measured distributions with distributions produced by tracking the reconstructed initial distributions, it is proved that the real or quasi-real (closest to real) initial distribution can be obtained as long as the minimum distribution discrepancy is found.
	Slides SUPAF10 [8.261 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF10
About •	paper received ※ 18 October 2018 paper accepted ※ 27 January 2019 issue date ※ 26 January 2019
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SUPAG01	Space Charge and Transverse Instabilities at the CERN SPS and LHC	80
	E. Métral, D. Amorim, G. Arduini, H. Bartosik, E. Benedetto, H. Burkhardt, K.S.B. Li, A. Oeftiger, D. Quatraro, G. Rumolo, B. Salvant, C. Zannini CERN, Geneva, Switzerland
	At the CERN accelerator complex, it seems that only the highest energy machine in the sequence, the LHC, with space charge (SC) parameter close to one, sees the predicted beneficial effect of SC on transverse coherent instabilities. In the other circular machines of the LHC injector chain (PSB, PS and SPS), where the SC parameter is much bigger than one, SC does not seem to play a major (stabilising) role, and it is maybe the opposite in the SPS. All the measurements and simulations performed so far in both the SPS and LHC will be reviewed and analysed in detail.
	Slides SUPAG01 [37.523 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAG01
About •	paper received ※ 20 October 2018 paper accepted ※ 19 November 2018 issue date ※ 26 January 2019
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SUPAG06	Simulation Challenges for eRHIC Beam-Beam Study	99
	Y. Luo BNL, Upton, Long Island, New York, USA Y. Hao FRIB, East Lansing, USA J. Qiang LBNL, Berkeley, California, USA Y. Roblin JLab, Newport News, Virginia, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The 2015 Nuclear Science Advisory Committee Long Rang Plan identified the need for an electron-ion collider facility as a gluon microscope with capabilities beyond those of any existing accelerator complex. To reach the required high energy, high luminosity, and high polarization, the eRHIC design based on the existing heady ion and polarized proton collider RHIC adopts a very small beta-function at the interaction point, a high collision repetition rate, and a novel hadron cooling scheme. Collision with a full crossing angle of 22 mrad and crab cavities for both electron and proton rings are required. In this article, we will present the high priority R&D items related to beam-beam interaction for the current eRHIC design, the simulation challenges, and our plans to address them.
	Slides SUPAG06 [2.395 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAG06
About •	paper received ※ 18 October 2018 paper accepted ※ 03 December 2018 issue date ※ 26 January 2019
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MOPAF02	Realistic Modeling of the Muon g-2 Experiment Beamlines at Fermilab	134
	D. Tarazona, M. Berz, K. Makino MSU, East Lansing, Michigan, USA D. Stratakis, M.J. Syphers Fermilab, Batavia, Illinois, USA M.J. Syphers Northern Illinois University, DeKalb, Illinois, USA
	Funding: This work is supported by the U.S. Department of Energy under Award No. DE-FG02-08ER41546, by the PhD Accelerator Program at Fermilab, and by a Strategic Partnership Grant from the MSU Foundation. The main goal of the Muon g-2 Experiment at Fermilab (E989) is to measure the muon anomalous magnetic moment (a, also dubbed as the "anomaly’’) to unprecedented precision. This new measurement will allow to test the completeness of the Standard Model (SM) and to validate other theoretical models beyond the SM. Simulations of the beamlines from the pion production target to the entrance of the g-2 Storage Ring using COSY INFINITY contribute to the understanding and characterization of the muon beam production in relation to the statistical and systematics uncertainties of the E989 measurement. The effect of nonlinearites from fringe fields and high-order contributions on the beam delivery system performance are considered, as well as interactions with the beamline elements apertures, particle decay channels, spin dynamics, and beamline misalignments.
	Slides MOPAF02 [14.110 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-MOPAF02
About •	paper received ※ 22 October 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019
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TUPAF01	Upgrade of MAD-X for HL-LHC Project and FCC Studies	165
	L. Deniau, H. Burkhardt, R. De Maria, M. Giovannozzi, J.M. Jowett, A. Latina, T. Persson, F. Schmidt, I.S. Shreyber, P.K. Skowroński CERN, Geneva, Switzerland T.G. Gläßle HIT, Heidelberg, Germany
	The design efforts for the High Luminosity upgrade of the Large Hadron Collider (HL-LHC) and for the FCC-ee project required significant extensions of the MAD-X code widely used for designing and simulating particle accelerators. The modelling of synchrotron radiation effects has recently been reviewed, improved and tested on the lattices of ESRF, LEP and CLIC Final Focus System. The results were cross checked with the codes AT, PLACET, Geant4, and MAD8. The implementation of space charge has been drastically restructured in a modular design. The linear coupling calculation has been completely reviewed and improved, from the theory to the implementation in MAD-X code to ensure its correctness in the presence of strong coupling as in the HL-LHC studies. The slicing module has been generalised to allow for thick slices of bending magnets, quadrupoles and solenoids. The SBEND element has been extended to support difference between bending angle and integrated dipole strength. Patches have been added to the list of supported elements. MAD-X PTC has also been extended to track resonance driving terms along layouts, and to support AC dipoles to simulate beams during optics measurements.
	Slides TUPAF01 [5.986 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF01
About •	paper received ※ 17 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019
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TUPAF02	SixTrack Project: Status, Runtime Environment, and New Developments	172
	R. De Maria, J. Andersson, L. Field, M. Giovannozzi, P.D. Hermes, N. Hoimyr, G. Iadarola, S. Kostoglou, E.H. Maclean, E. McIntosh, A. Mereghetti, J. Molson, V.K.B. Olsen, D. Pellegrini, T. Persson, M. Schwinzerl, K.N. Sjobak CERN, Geneva, Switzerland E.H. Maclean University of Malta, Information and Communication Technology, Msida, Malta S. Singh Indian Institute of Technology Madras, Chennai, India K.N. Sjobak University of Oslo, Oslo, Norway I. Zacharov EPFL, Lausanne, Switzerland
	Funding: Research supported by the HL-LHC project and Google Summer of Code 2018. SixTrack is a single-particle tracking code for high-energy circular accelerators routinely used at CERN for the Large Hadron Collider (LHC), its luminosity upgrade (HL-LHC), the Future Circular Collider (FCC), and the Super Proton Synchrotron (SPS) simulations. The code is based on a 6D symplectic tracking engine, which is optimised for long-term tracking simulations and delivers fully reproducible results on several platforms. It also includes multiple scattering engines for beam-matter interaction studies, as well as facilities to run integrated simulations with FLUKA and GEANT4. These features differentiate SixTrack from general-purpose, optics-design software like MAD-X. The code recently underwent a major restructuring to merge advanced features into a single branch, such as multiple ion species, interface with external codes, and high-performance input/output (XRootD, HDF5). This restructuring also removed a large number of build flags, instead enabling/disabling the functionality at run-time. In the process, the code was moved from Fortran 77 to Fortran 2018 standard, also allowing and achieving a better modularization. Physics models (beam-beam effects, RF-multipoles, current carrying wires, solenoid, and electron lenses) and methods (symplecticity check) have also been reviewed and refined to offer more accurate results. The SixDesk runtime environment allows the user to manage the large batches of simulations required for accurate predictions of the dynamic aperture. SixDesk supports CERN LSF and HTCondor batch systems, as well as the BOINC infrastructure in the framework of the LHC@Home volunteering computing project. SixTrackLib is a new library aimed at providing a portable and flexible tracking engine for single- and multi-particle problems using the models and formalism of SixTrack. The tracking routines are implemented in a parametrized C code that is specialised to run vectorized in CPUs and GPUs, by using SIMD intrinsics, OpenCL 1.2, and CUDA tech
	Slides TUPAF02 [0.938 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF02
About •	paper received ※ 18 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019
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TUPAF06	Simulations of Longitudinal Beam Stabilisation in the CERN SPS With BLonD	179
	J. Repond, K. Iliakis, M. Schwarz, E.N. Shaposhnikova CERN, Meyrin, Switzerland
	The Super Proton Synchrotron (SPS) at CERN, the Large Hadron Collider (LHC) injector, will be pushed to its limits for the production of the High Luminosity LHC proton beam while beam quality and stability in the longitudinal plane are influenced by many effects. Particle simulation codes are an essential tool to study the beam instabilities. BLonD, developed at CERN, is a 2D particle-tracking simulation code, modelling the longitudinal phase space motion of single and multi-bunch beams in multi-harmonic RF systems. Computation of collective effects due to the machine impedance and space charge is done on a multi-turn basis. Various beam and cavity control loops of the RF system are implemented (phase, frequency and synchro-loops, and one-turn delay feedback) as well as RF phase noise injection used for controlled emittance blow-up. The longitudinal beam stability simulations during long SPS acceleration cycle (~ 20 s) include a variety of effects (beam loading, particle losses, controlled blow-up, double RF system operation, low-level RF control, injected bunch distribution, etc.). Simulations for the large number of bunches in the nominal LHC batch (288) use the longitudinal SPS impedance model containing broad and narrow-band resonances between 50 MHz and 4 GHz. This paper presents a study of beam stabilisation in the double harmonic RF system of the SPS system with results substantiated, where possible, by beam measurements.
	Slides TUPAF06 [1.518 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF06
About •	paper received ※ 18 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019
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TUPAF20	Mean-Field Density Evolution of Bunched Particles With Non-Zero Initial Velocity	233
	B.S. Zerbe, P.M. Duxbury MSU, East Lansing, Michigan, USA
	Funding: NSF Grant 1625181 NSF Grant RC108666 MSU Col. Nat. Sci., Provost Off., Col. Comm. Art and Sci. Reed (2006) presented a 1D mean-field model of initially cold pancake-beam expansion demonstrating that the evolution of the entire spatial distribution can be solved for all time where the 1D assumption holds. This model is relevant to ultra-fast electron microscopy as it describes the evolution of the distribution within the photoelectron gun, and this model is similar to Anderson’s sheet beam density time dependence (Anderson 1987) except that Reed’s theory applies to freely expanding beams instead of beams within a focussing channel. Our recent work (Zerbe 2018) generalized Reed’s analysis to cylindrical and spherical geometries demonstrating the presence of a shock that is seen in the Coulomb explosion literature under these geometries and further discussed the absence of a shock in the 1D model. This work is relevant as it offers a mechanistic explanation of the ring-like density shock that arises in non-equilibrium pancake-beams within the photoelectron gun; moreover, this shock is coincident with a region of high-temperature electrons providing an explanation for why experimentally aperturing the electron bunch results in a greater than 10-fold improvement in beam emittance(Williams 2017), possibly even resulting in bunch emittance below the intrinsic emittance of the cathode. However, this theory has been developed for cold-bunches, i.e. bunches of electrons with 0 initial momentum. Here, we briefly review this new theory and extend the cylindrical- and spherical- symmetric distribution to ensembles that have non-zero initial momentum distributions that are symmetric but otherwise unrestricted demonstrating how initial velocity distributions couple to the shocks seen in the less general formulation. Further, we derive and demonstrate how the laminar condition may be propagated through beam foci.
	Slides TUPAF20 [1.396 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF20
About •	paper received ※ 19 October 2018 paper accepted ※ 15 December 2018 issue date ※ 26 January 2019
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TUPAF23	Start-to-End Simulations of THz SASE FEL Proof-of-Principle Experiment at PITZ	246
	M. Krasilnikov, P. Boonpornprasert, F. Stephan DESY Zeuthen, Zeuthen, Germany H.-D. Nuhn SLAC, Menlo Park, California, USA E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	The Photo Injector Test facility at DESY in Zeuthen (PITZ) develops high brightness electron sources for modern linac-based Free Electron Lasers (FELs). The PITZ accelerator has been proposed as a prototype for a tunable, high power THz source for pump and probe experiments at the European XFEL. A Self-Amplified Spontaneous Emission (SASE) FEL is considered to generate the THz pulses. High radiation power can be achieved by utilizing high charge (4 nC) shaped electron bunches from the PITZ photo injector. THz pulse energy of up to several mJ is expected from preliminary simulations for 100 um radiation wavelength. For the proof-of-principle experiments a re-usage of LCLS-I undulators at the end of the PITZ beamline is under studies. One of the challenges for this setup is transport and matching of the space charge dominated electron beam through the narrow vacuum chamber. Start-to-end simulations for the entire experimental setup - from the photocathode to the SASE THz generation in the undulator section - have been performed by combination of several codes: ASTRA, SC and GENESIS-1.3. The space charge effect and its impact onto the output THz radiation have been studied. The results of these simulations will be presented and discussed.
	Slides TUPAF23 [2.534 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF23
About •	paper received ※ 18 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019
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TUPAG02	First Steps Towards a New Finite Element Solver for MOEVE PIC Tracking	260
	U. van Rienen, C.R. Bahls, J. Heller, D. Zheng Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany U. van Rienen University of Rostock, Rostock, Germany
	Funding: This work has been supported by the German Federal Ministry for Research and Education BMBF under contract 015K16HRA. A relevant task in designing high-brilliance light sources based on high-current linear accelerators (e.g. Energy Recovery Linacs (ERLs)) consists in systematic investigations of ion dynamics in the vacuum chamber of such machines. This is of high importance since the parasitic ions generated by the electron beam turned out to be a current-limiting factor for many synchrotron radiation sources. In particular, the planned high current operation at ERL facilities requires a precise analysis and an accurate development of appropriate measures for the suppression of ion-induced beam instabilities. The longitudinal transport of ions through the whole accelerator plays a key role for the establishment of the ion concentration in the machine. Using the Particle-in-Cell (PIC) method, we started redesigning our code MOEVE PIC Tracking in order to allow for the fast estimation of the effects of ions on the beam dynamics. For that, we exchanged the previously used Finite Difference (FD) method for the solution of Poisson’s equation within the PIC solver by a solver based on the Finite Element Method (FEM). Employing higher order FEM, we expect to gain improved convergence rates and thus lower computational times. We chose the Open Source Framework FEniCS for our new implementation.
	Slides TUPAG02 [0.924 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG02
About •	paper received ※ 21 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019
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TUPAG05	Trimcoil Optimisation Using Multi-Objective Optimisation Techniques and HPC
	M. Frey, A. Adelmann, J. Snuverink PSI, Villigen PSI, Switzerland
	Funding: SNSF project 200021₁59936 Uncertainties in the bunch injection (i.e. energy, radius, radial momentum and angle) as well as magnet inaccuracies harm the isochronicity of the PSI 590 MeV Ring Cyclotron. An additional magnetic field provided by trim coils is an effective solution to restore this condition. Therefore, an accurate description of trim coils is essential to match the turn pattern of the machine in simulations. However, due to the high-dimensional search space consisting of 21 design variables and more than 180 objectives the turns cannot be matched in a straightforward manner and without sufficient HPC resources. In this talk we present a realistic trim coil model for the PSI 590 MeV Ring Cyclotron implemented in OPAL that was used together with its built-in multi-objective optimisation algorithm to find the 4 injection parameters and the magnetic field strengths of 17 trim coils. The optimisations were performed on Piz Daint (currently 3rd fastest supercomputer world-wide) with more than 1000 cores per job.
	Slides TUPAG05 [6.765 MB]
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TUPAG10	Nonlinear Optics at UMER: Lessons Learned in Simulation	278
	K.J. Ruisard, B.L. Beaudoin, I. Haber, T.W. Koeth, D.B. Matthew UMD, College Park, Maryland, USA
	Funding: Funding through DOEHEP Award DESC0010301, NSF Award PHY1414681, NSF GRFP program. Manuscript authored by UT-Battelle, LLC, under Contract No. DEAC0500OR22725 with the U.S. Department of Energy. Invited talk: Design of accelerator lattices with nonlinear optics to suppress transverse resonances is a novel approach and may be crucial for enabling low-loss high-intensity beam transport. Large amplitude-dependent tune spreads, driven by nonlinear field inserts, damp resonant response to driving terms. This presentation will focus on simulations of the UMER lattice operated as a quasi-integrable system (1 invariant of transverse motion) with a single strong octupole insert. We will discuss the evolution of simulation models, including the observation of losses associated with the original operating point near a fourth-order resonance. Other operating points farther from this resonance are considered and shown to be more promising.
	Slides TUPAG10 [3.447 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG10
About •	paper received ※ 19 October 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019
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TUPAG11	ESS Accelerator Lattice Design Studies and Automatic Synoptic Deployment	285
	Y. Levinsen, R. De Prisco, M. Eshraqi, T.J. Grandsaert, A. Jansson, H. Kocevar, Ø. Midttun, N. Milas, R. Miyamoto, D.C. Plostinar, A. Ponton, T.J. Shea ESS, Lund, Sweden H.D. Thomsen AU, Aarhus, Denmark
	The European Spallation Source (ESS) is currently under construction in the south of Sweden. A highly brilliant neutron source with a 5 MW proton driver will provide state of the art experimental facilities for neutron science. A peak proton beam power in the accelerator of 125 MW means that excellent control over the beam losses becomes essential. The beam physics design of the ESS accelerator is in a TraceWin format, for which we have developed revision control setup, automated regression analysis and deployment of synoptic viewer and tabulated spreadsheets. This allows for an integrated representation of the data that are always kept synchronized and available to other engineering disciplines. The design of the accelerator lattice has gone through several major and minor iterations which are all carefully analysed. In this contribution we present the status of the latest studies which is the first time a complete end-to-end study beginning from the ion source has been performed.
	Slides TUPAG11 [7.733 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG11
About •	paper received ※ 18 October 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019
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TUPAG13	S-Based Macro-Particle Spectral Algorithm for an Electron Gun	290
	P. M. Jung, T. Planche TRIUMF, Vancouver, Canada
	We derive a Hamiltonian description of a continuous particle distribution and its electrostatic potential from the Low Lagrangian. The self consistent space charge potential is discretized according to the spectral Galerkin approximation. The particle distribution is discretized using macro-particles. We choose a set of initial and boundary conditions to model the TRIUMF 300keV thermionic DC electron gun. The field modes and macro-particle coordinates are integrated self-consistently. The current status of the implementation is discussed.
	Slides TUPAG13 [1.335 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG13
About •	paper received ※ 01 November 2018 paper accepted ※ 10 December 2018 issue date ※ 26 January 2019
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WEPAF02	Simulations of Beam Chopping for Potential Upgrades of the SNS LEBT Chopper	325
	B. Han, S.N. Murray, T.R. Pennisi, V.V. Peplov, M.P. Stockli, R.F. Welton ORNL, Oak Ridge, Tennessee, USA R.B. Saethre, C. Stinson ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This work was performed at Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, under contract number DE-AC05-00OR22725 for the United States Department of Energy. The LEBT chopper is a critical element of the SNS accelerator system. In this work, the benefit of increasing the chopping voltage amplitude for the present chopping pattern is shown with beam simulations, and an ongoing hardware upgrade of the chopper pulser units is discussed. In addition, with the prospect of higher voltage capability of the new pulser design, two alternative chopping patterns which reduce the switching frequency of the chopper pulsers down to 1/2 or 1/4 of the present chopping pattern, are also explored with beam simulations.
	Slides WEPAF02 [7.431 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPAF02
About •	paper received ※ 31 October 2018 paper accepted ※ 07 December 2018 issue date ※ 26 January 2019
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WEPAF03	Magnetized Electron Cooling Simulations for JLEIC
	I.V. Pogorelov, D.T. Abell, D.L. Bruhwiler, J.A. Carlsson, Y.I. Eidelman, C.C. Hall, S.D. Webb RadiaSoft LLC, Boulder, Colorado, USA J. Gerity, P.M. McIntyre Texas A&M University, College Station, USA H. Zhang, Y. Zhang JLab, Newport News, Virginia, USA
	Funding: This work is supported by the U.S. DOE Office of Science, Office of Nuclear Physics, under Award Number DE-SC0015212. Relativistic magnetized electron cooling in untested parameter regimes is essential to achieve the ion luminosity requirements of proposed electron-ion collider (EIC) designs. Therefore, accurate calculations of magnetized dynamic friction are required, with the ability to include all relevant physics that might increase the cooling time, including space charge forces, field errors and complicated phase space distributions of imperfectly magnetized electron beams. We present simulations relevant to the JLEIC design, using the BETACOOL and JSPEC codes. We also present recent work on Warp simulations of the electron beam through the solenoid field. Space charge neutralization is provided by impact ionization of a background hydrogen gas. For optimal cooling it is essential that space charge be sufficiently neutralized. We also present recent work on a new analytic treatment of momentum transfer from a single magnetized electron to a drifting ion, and its use for calculations of dynamic friction.
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WEPLG01	Analysis of Emittance Growth in a Gridless Spectral Poisson Solver for Fully Symplectic Multiparticle Tracking	335
	C.E. Mitchell, J. Qiang LBNL, Berkeley, California, USA
	Funding: This work was supported by the Director, Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Gridless spectral methods for self-consistent symplectic space charge modeling possess several advantages over traditional momentum-conserving particle-in-cell methods, including the absence of numerical grid heating and the presence of an underlying multi-particle Hamiltonian. Nevertheless, evidence of collisional particle noise remains. For a class of such 1D and 2D algorithms, we provide analytical models of the numerical field error, the optimal choice of spectral modes, and the numerical emittance growth per timestep. We compare these results with the emittance growth models of Struckmeier, Hoffman, Kesting, and others.
	Slides WEPLG01 [11.804 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPLG01
About •	paper received ※ 18 October 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019
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WEPLG02	REPTIL - A Relativistic 3D Space Charge Particle Tracking Code Based on the Fast Multipole Method
	S. A. Schmid, H. De Gersem, E. Gjonaj TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: This work is supported by the DFG in the framework of GRK 2128. Modern free electron lasers and high current energy recovery linacs accelerate electron beams with particle bunch charges reaching up to several nanocoulombs. Especially in the low energy sections, such as the photoinjector of the accelerator, space charge interaction forces are the dominating effect influencing the dynamics of the electron beam. A direct computation of space charge forces is numerically very expensive. Commonly used simulation codes typically apply mesh based particle-in-cell methods (PIC) to solve this problem. Our simulation tool, REPTIL, is a relativistic, three-dimensional space charge tracking code, which computes the interaction forces based on a meshless fast multipole method (FMM). The FMM based space charge solver is more flexible regarding the choice of the interaction model and yields maximum accuracy for the near field forces between particles. For this reason, the FMM is very suitable for the simulation of the influence of space charge on the particle emission process in high current photoinjectors. In this contribution, we present a numerical study of the efficiency and the accuracy of the method. Therefore, we perform a case study for the PITZ photoinjector used for the European XFEL at DESY. Furthermore, we compare the performance of REPTIL with commonly used PIC codes like e.g. ASTRA. Finally, we investigate a hybrid approach by using the FMM on a mesh. The latter method makes further increases in the particle number possible, which translates to a higher resolution in the phase space of the electron bunch.
	Slides WEPLG02 [2.443 MB]
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Paper

Title

Page

Advances in Simulation of High Brightness/High Intensity Beams

1

J. Qiang
LBNL, Berkeley, California, USA

High brightness/high intensity beams play an important role in accelerator based applications by driving x-ray free electron laser (FEL) radiation, producing spallation neutrons and neutrinos, and generating new particles in high energy colliders. In this paper, we report on recent advances in modeling the high brightness electron beam with application to the next generation FEL light sources and in modeling space-charge effects in high intensity proton accelerators.

Slides SAPLG01 [3.914 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SAPLG01

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paper received ※ 02 November 2018 paper accepted ※ 19 November 2018 issue date ※ 26 January 2019

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SAPAG02

Beam Dynamics Simulations and Challenges for the FAIR SIS100 Synchrotron

O. Boine-Frankenheim, V. Chetvertkova, V. Kornilov, S. Sorge
GSI, Darmstadt, Germany

The SIS100 synchrotron is the central accelerator of the upcoming FAIR project at GSI, Darmstadt, Germany. The major challenges for the design studies and the later operation are related to high-intensity, low beam loss operation for a wide range of ion species and charge states, for different operational cycles and extraction schemes. We focus our simulation studies on the long (up to 1 s) accumulation plateau and on the final bunch compression before extraction. During accumulation emittance growth and beam loss due to transverse space charge in combination with the magnet field errors has to be well controlled. We use different simulation approaches with frozen and self-consistent "symplectic" space charge solvers to identify optimum working point areas, including realistic field error models for the superconducting, superferric SIS100 dipole and quadrupole magnets.

Slides SAPAG02 [1.887 MB]

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SUPAF02

Beam Alignment Simulation on the Beamline of a Proton Therapy Facility

X. Liu, Q.S. Chen, G. Feng, B. Qin
HUST, Wuhan, People’s Republic of China

Proton therapy is now recognized as one of the most effective radiation therapy methods for cancers. A proton therapy facility with multiple gantry treatment rooms is under development in HUST (Huazhong University of Science and Technology). Misalignments of magnets and beam diagnostics instruments induce the offset of the beam trajectory, which will influence the clinical therapeutic effect. This paper describes the beam alignment simulations based on response matrix and this technology is applied to the design of the HUST-PTF beamline. To perform this study, we use the simulation code ELEGANT, and utilize the global correction method. By optimizing the layout of correctors and beam position monitors, we completed the beam correction calculation. The results show that the accuracy of center beam trajectory in the iso-center is better than 0.5 mm, meeting physical and clinical requirements.

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SUPAF06

Simulations of Coherent Electron Cooling With Free Electron Laser Amplifier and Plasma-Cascade Micro-Bunching Amplifier

52

J. Ma, V. Litvinenko, G. Wang
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

SPACE is a parallel, relativistic 3D electromagnetic Particle-in-Cell (PIC) code used for simulations of beam dynamics and interactions. An electrostatic module has been developed with the implementation of Adaptive Particle-in-Cloud method. Simulations performed by SPACE are capable of various beam distribution, different types of boundary conditions and flexible beam line, as well as sufficient data processing routines for data analysis and visualization. Code SPACE has been used in the simulation studies of coherent electron cooling experiment based on two types of amplifiers, the free electron laser (FEL) amplifier and the plasma-cascade micro-bunching amplifier.

Slides SUPAF06 [1.260 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF06

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paper received ※ 15 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019

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SUPAF09

Sparse Grid Particle-in-Cell Scheme for Noise Reduction in Beam Simulations

71

A.J. Cerfon
Courant Institute of Mathematical Sciences, New York University, New York, USA
L.F. Ricketson
LLNL, Livermore, California, USA

The complexity of standard solvers grows exponentially with the number of dimensions of the underlying equations. This issue is particularly acute for continuum solvers, which need to discretize the six-dimensional phase-space distribution function, and whose run times are consequently large even for a moderate number of grid points for each dimension. Particle-in-Cell (PIC) schemes are a popular alternate approach to continuum methods, because they only discretize the three-dimensional physical space and are therefore less subject to the curse of dimensionality. Even if so, PIC solvers still have large run times, because of the statistical error which is inherent to particle methods and which decays slowly with the number of particles per cell. In this talk, we will present a new scheme to address the curse of dimensionality and at the same time reduce the numerical noise of PIC simulations. Our PIC scheme is inspired by the sparse grids combination technique, a method invented to reduce grid based error when solving high dimensional partial differential equations [1]. The technique, when applied to the PIC method, has two benefits: 1) it almost eliminates the dependence of the grid based error on dimensionality, just like in a standard sparse grids application; 2) it lowers the statistical error significantly, because the sparse grids have larger cells, and thus a larger number of particles per cell for a given total number of particles. We will analyze the performance of our scheme for standard test problems in beam physics. We will demonstrate remarkable speed up for a certain class of problems, and less impressive performance for others. The latter will allow us to identify the limitations of our scheme and explore ideas to address them.
[1] Griebel M et al. 1990 A combination technique for the solution of sparse grid problems Iterative Methods in Linear Algebra ed R Bequwens and P de Groen (Amsterdam: Elsevier) pp 263-81

Slides SUPAF09 [1.848 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF09

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paper received ※ 19 October 2018 paper accepted ※ 19 November 2018 issue date ※ 26 January 2019

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SUPAF10

Reconstruction of Particle Distributions at RFQ Exit at SNS Beam Test Facility

76

Z.L. Zhang
ORNL RAD, Oak Ridge, Tennessee, USA
A.V. Aleksandrov, S.M. Cousineau
ORNL, Oak Ridge, Tennessee, USA

Fluctuations of beam parameters and uncertainties of quadrupole gradients during measurements have effects on the reconstruction of initial particle distributions. To evaluate these effects, the concept of a distribution discrepancy is proposed. Results suggest effects of fluctuations of beam parameters are small, while uncertainties of quadrupole gradients are the main factors that affect the reconstructed distributions. By comparing the measured distributions with distributions produced by tracking the reconstructed initial distributions, it is proved that the real or quasi-real (closest to real) initial distribution can be obtained as long as the minimum distribution discrepancy is found.

Slides SUPAF10 [8.261 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF10

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paper received ※ 18 October 2018 paper accepted ※ 27 January 2019 issue date ※ 26 January 2019

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SUPAG01

Space Charge and Transverse Instabilities at the CERN SPS and LHC

80

E. Métral, D. Amorim, G. Arduini, H. Bartosik, E. Benedetto, H. Burkhardt, K.S.B. Li, A. Oeftiger, D. Quatraro, G. Rumolo, B. Salvant, C. Zannini
CERN, Geneva, Switzerland

At the CERN accelerator complex, it seems that only the highest energy machine in the sequence, the LHC, with space charge (SC) parameter close to one, sees the predicted beneficial effect of SC on transverse coherent instabilities. In the other circular machines of the LHC injector chain (PSB, PS and SPS), where the SC parameter is much bigger than one, SC does not seem to play a major (stabilising) role, and it is maybe the opposite in the SPS. All the measurements and simulations performed so far in both the SPS and LHC will be reviewed and analysed in detail.

Slides SUPAG01 [37.523 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAG01

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paper received ※ 20 October 2018 paper accepted ※ 19 November 2018 issue date ※ 26 January 2019

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SUPAG06

Simulation Challenges for eRHIC Beam-Beam Study

99

Y. Luo
BNL, Upton, Long Island, New York, USA
Y. Hao
FRIB, East Lansing, USA
J. Qiang
LBNL, Berkeley, California, USA
Y. Roblin
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The 2015 Nuclear Science Advisory Committee Long Rang Plan identified the need for an electron-ion collider facility as a gluon microscope with capabilities beyond those of any existing accelerator complex. To reach the required high energy, high luminosity, and high polarization, the eRHIC design based on the existing heady ion and polarized proton collider RHIC adopts a very small beta-function at the interaction point, a high collision repetition rate, and a novel hadron cooling scheme. Collision with a full crossing angle of 22 mrad and crab cavities for both electron and proton rings are required. In this article, we will present the high priority R&D items related to beam-beam interaction for the current eRHIC design, the simulation challenges, and our plans to address them.

Slides SUPAG06 [2.395 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAG06

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paper received ※ 18 October 2018 paper accepted ※ 03 December 2018 issue date ※ 26 January 2019

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MOPAF02

Realistic Modeling of the Muon g-2 Experiment Beamlines at Fermilab

134

D. Tarazona, M. Berz, K. Makino
MSU, East Lansing, Michigan, USA
D. Stratakis, M.J. Syphers
Fermilab, Batavia, Illinois, USA
M.J. Syphers
Northern Illinois University, DeKalb, Illinois, USA

Funding: This work is supported by the U.S. Department of Energy under Award No. DE-FG02-08ER41546, by the PhD Accelerator Program at Fermilab, and by a Strategic Partnership Grant from the MSU Foundation.
The main goal of the Muon g-2 Experiment at Fermilab (E989) is to measure the muon anomalous magnetic moment (a, also dubbed as the "anomaly’’) to unprecedented precision. This new measurement will allow to test the completeness of the Standard Model (SM) and to validate other theoretical models beyond the SM. Simulations of the beamlines from the pion production target to the entrance of the g-2 Storage Ring using COSY INFINITY contribute to the understanding and characterization of the muon beam production in relation to the statistical and systematics uncertainties of the E989 measurement. The effect of nonlinearites from fringe fields and high-order contributions on the beam delivery system performance are considered, as well as interactions with the beamline elements apertures, particle decay channels, spin dynamics, and beamline misalignments.

Slides MOPAF02 [14.110 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-MOPAF02

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paper received ※ 22 October 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019

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TUPAF01

Upgrade of MAD-X for HL-LHC Project and FCC Studies

165

L. Deniau, H. Burkhardt, R. De Maria, M. Giovannozzi, J.M. Jowett, A. Latina, T. Persson, F. Schmidt, I.S. Shreyber, P.K. Skowroński
CERN, Geneva, Switzerland
T.G. Gläßle
HIT, Heidelberg, Germany

The design efforts for the High Luminosity upgrade of the Large Hadron Collider (HL-LHC) and for the FCC-ee project required significant extensions of the MAD-X code widely used for designing and simulating particle accelerators. The modelling of synchrotron radiation effects has recently been reviewed, improved and tested on the lattices of ESRF, LEP and CLIC Final Focus System. The results were cross checked with the codes AT, PLACET, Geant4, and MAD8. The implementation of space charge has been drastically restructured in a modular design. The linear coupling calculation has been completely reviewed and improved, from the theory to the implementation in MAD-X code to ensure its correctness in the presence of strong coupling as in the HL-LHC studies. The slicing module has been generalised to allow for thick slices of bending magnets, quadrupoles and solenoids. The SBEND element has been extended to support difference between bending angle and integrated dipole strength. Patches have been added to the list of supported elements. MAD-X PTC has also been extended to track resonance driving terms along layouts, and to support AC dipoles to simulate beams during optics measurements.

Slides TUPAF01 [5.986 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF01

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paper received ※ 17 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019

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TUPAF02

SixTrack Project: Status, Runtime Environment, and New Developments

172

R. De Maria, J. Andersson, L. Field, M. Giovannozzi, P.D. Hermes, N. Hoimyr, G. Iadarola, S. Kostoglou, E.H. Maclean, E. McIntosh, A. Mereghetti, J. Molson, V.K.B. Olsen, D. Pellegrini, T. Persson, M. Schwinzerl, K.N. Sjobak
CERN, Geneva, Switzerland
E.H. Maclean
University of Malta, Information and Communication Technology, Msida, Malta
S. Singh
Indian Institute of Technology Madras, Chennai, India
K.N. Sjobak
University of Oslo, Oslo, Norway
I. Zacharov
EPFL, Lausanne, Switzerland

Funding: Research supported by the HL-LHC project and Google Summer of Code 2018.
SixTrack is a single-particle tracking code for high-energy circular accelerators routinely used at CERN for the Large Hadron Collider (LHC), its luminosity upgrade (HL-LHC), the Future Circular Collider (FCC), and the Super Proton Synchrotron (SPS) simulations. The code is based on a 6D symplectic tracking engine, which is optimised for long-term tracking simulations and delivers fully reproducible results on several platforms. It also includes multiple scattering engines for beam-matter interaction studies, as well as facilities to run integrated simulations with FLUKA and GEANT4. These features differentiate SixTrack from general-purpose, optics-design software like MAD-X. The code recently underwent a major restructuring to merge advanced features into a single branch, such as multiple ion species, interface with external codes, and high-performance input/output (XRootD, HDF5). This restructuring also removed a large number of build flags, instead enabling/disabling the functionality at run-time. In the process, the code was moved from Fortran 77 to Fortran 2018 standard, also allowing and achieving a better modularization. Physics models (beam-beam effects, RF-multipoles, current carrying wires, solenoid, and electron lenses) and methods (symplecticity check) have also been reviewed and refined to offer more accurate results. The SixDesk runtime environment allows the user to manage the large batches of simulations required for accurate predictions of the dynamic aperture. SixDesk supports CERN LSF and HTCondor batch systems, as well as the BOINC infrastructure in the framework of the LHC@Home volunteering computing project. SixTrackLib is a new library aimed at providing a portable and flexible tracking engine for single- and multi-particle problems using the models and formalism of SixTrack. The tracking routines are implemented in a parametrized C code that is specialised to run vectorized in CPUs and GPUs, by using SIMD intrinsics, OpenCL 1.2, and CUDA tech

Slides TUPAF02 [0.938 MB]

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TUPAF06

Simulations of Longitudinal Beam Stabilisation in the CERN SPS With BLonD

179

J. Repond, K. Iliakis, M. Schwarz, E.N. Shaposhnikova
CERN, Meyrin, Switzerland

The Super Proton Synchrotron (SPS) at CERN, the Large Hadron Collider (LHC) injector, will be pushed to its limits for the production of the High Luminosity LHC proton beam while beam quality and stability in the longitudinal plane are influenced by many effects. Particle simulation codes are an essential tool to study the beam instabilities. BLonD, developed at CERN, is a 2D particle-tracking simulation code, modelling the longitudinal phase space motion of single and multi-bunch beams in multi-harmonic RF systems. Computation of collective effects due to the machine impedance and space charge is done on a multi-turn basis. Various beam and cavity control loops of the RF system are implemented (phase, frequency and synchro-loops, and one-turn delay feedback) as well as RF phase noise injection used for controlled emittance blow-up. The longitudinal beam stability simulations during long SPS acceleration cycle (~ 20 s) include a variety of effects (beam loading, particle losses, controlled blow-up, double RF system operation, low-level RF control, injected bunch distribution, etc.). Simulations for the large number of bunches in the nominal LHC batch (288) use the longitudinal SPS impedance model containing broad and narrow-band resonances between 50 MHz and 4 GHz. This paper presents a study of beam stabilisation in the double harmonic RF system of the SPS system with results substantiated, where possible, by beam measurements.

Slides TUPAF06 [1.518 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF06

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paper received ※ 18 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019

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TUPAF20

Mean-Field Density Evolution of Bunched Particles With Non-Zero Initial Velocity

233

B.S. Zerbe, P.M. Duxbury
MSU, East Lansing, Michigan, USA

Funding: NSF Grant 1625181 NSF Grant RC108666 MSU Col. Nat. Sci., Provost Off., Col. Comm. Art and Sci.
Reed (2006) presented a 1D mean-field model of initially cold pancake-beam expansion demonstrating that the evolution of the entire spatial distribution can be solved for all time where the 1D assumption holds. This model is relevant to ultra-fast electron microscopy as it describes the evolution of the distribution within the photoelectron gun, and this model is similar to Anderson’s sheet beam density time dependence (Anderson 1987) except that Reed’s theory applies to freely expanding beams instead of beams within a focussing channel. Our recent work (Zerbe 2018) generalized Reed’s analysis to cylindrical and spherical geometries demonstrating the presence of a shock that is seen in the Coulomb explosion literature under these geometries and further discussed the absence of a shock in the 1D model. This work is relevant as it offers a mechanistic explanation of the ring-like density shock that arises in non-equilibrium pancake-beams within the photoelectron gun; moreover, this shock is coincident with a region of high-temperature electrons providing an explanation for why experimentally aperturing the electron bunch results in a greater than 10-fold improvement in beam emittance(Williams 2017), possibly even resulting in bunch emittance below the intrinsic emittance of the cathode. However, this theory has been developed for cold-bunches, i.e. bunches of electrons with 0 initial momentum. Here, we briefly review this new theory and extend the cylindrical- and spherical- symmetric distribution to ensembles that have non-zero initial momentum distributions that are symmetric but otherwise unrestricted demonstrating how initial velocity distributions couple to the shocks seen in the less general formulation. Further, we derive and demonstrate how the laminar condition may be propagated through beam foci.

Slides TUPAF20 [1.396 MB]

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paper received ※ 19 October 2018 paper accepted ※ 15 December 2018 issue date ※ 26 January 2019

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TUPAF23

Start-to-End Simulations of THz SASE FEL Proof-of-Principle Experiment at PITZ

246

M. Krasilnikov, P. Boonpornprasert, F. Stephan
DESY Zeuthen, Zeuthen, Germany
H.-D. Nuhn
SLAC, Menlo Park, California, USA
E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

The Photo Injector Test facility at DESY in Zeuthen (PITZ) develops high brightness electron sources for modern linac-based Free Electron Lasers (FELs). The PITZ accelerator has been proposed as a prototype for a tunable, high power THz source for pump and probe experiments at the European XFEL. A Self-Amplified Spontaneous Emission (SASE) FEL is considered to generate the THz pulses. High radiation power can be achieved by utilizing high charge (4 nC) shaped electron bunches from the PITZ photo injector. THz pulse energy of up to several mJ is expected from preliminary simulations for 100 um radiation wavelength. For the proof-of-principle experiments a re-usage of LCLS-I undulators at the end of the PITZ beamline is under studies. One of the challenges for this setup is transport and matching of the space charge dominated electron beam through the narrow vacuum chamber. Start-to-end simulations for the entire experimental setup - from the photocathode to the SASE THz generation in the undulator section - have been performed by combination of several codes: ASTRA, SC and GENESIS-1.3. The space charge effect and its impact onto the output THz radiation have been studied. The results of these simulations will be presented and discussed.

Slides TUPAF23 [2.534 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF23

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paper received ※ 18 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019

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TUPAG02

First Steps Towards a New Finite Element Solver for MOEVE PIC Tracking

260

U. van Rienen, C.R. Bahls, J. Heller, D. Zheng
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
U. van Rienen
University of Rostock, Rostock, Germany

Funding: This work has been supported by the German Federal Ministry for Research and Education BMBF under contract 015K16HRA.
A relevant task in designing high-brilliance light sources based on high-current linear accelerators (e.g. Energy Recovery Linacs (ERLs)) consists in systematic investigations of ion dynamics in the vacuum chamber of such machines. This is of high importance since the parasitic ions generated by the electron beam turned out to be a current-limiting factor for many synchrotron radiation sources. In particular, the planned high current operation at ERL facilities requires a precise analysis and an accurate development of appropriate measures for the suppression of ion-induced beam instabilities. The longitudinal transport of ions through the whole accelerator plays a key role for the establishment of the ion concentration in the machine. Using the Particle-in-Cell (PIC) method, we started redesigning our code MOEVE PIC Tracking in order to allow for the fast estimation of the effects of ions on the beam dynamics. For that, we exchanged the previously used Finite Difference (FD) method for the solution of Poisson’s equation within the PIC solver by a solver based on the Finite Element Method (FEM). Employing higher order FEM, we expect to gain improved convergence rates and thus lower computational times. We chose the Open Source Framework FEniCS for our new implementation.

Slides TUPAG02 [0.924 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG02

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paper received ※ 21 October 2018 paper accepted ※ 24 October 2018 issue date ※ 26 January 2019

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TUPAG05

Trimcoil Optimisation Using Multi-Objective Optimisation Techniques and HPC

M. Frey, A. Adelmann, J. Snuverink
PSI, Villigen PSI, Switzerland

Funding: SNSF project 200021₁59936
Uncertainties in the bunch injection (i.e. energy, radius, radial momentum and angle) as well as magnet inaccuracies harm the isochronicity of the PSI 590 MeV Ring Cyclotron. An additional magnetic field provided by trim coils is an effective solution to restore this condition. Therefore, an accurate description of trim coils is essential to match the turn pattern of the machine in simulations. However, due to the high-dimensional search space consisting of 21 design variables and more than 180 objectives the turns cannot be matched in a straightforward manner and without sufficient HPC resources. In this talk we present a realistic trim coil model for the PSI 590 MeV Ring Cyclotron implemented in OPAL that was used together with its built-in multi-objective optimisation algorithm to find the 4 injection parameters and the magnetic field strengths of 17 trim coils. The optimisations were performed on Piz Daint (currently 3rd fastest supercomputer world-wide) with more than 1000 cores per job.

Slides TUPAG05 [6.765 MB]

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TUPAG10

Nonlinear Optics at UMER: Lessons Learned in Simulation

278

K.J. Ruisard, B.L. Beaudoin, I. Haber, T.W. Koeth, D.B. Matthew
UMD, College Park, Maryland, USA

Funding: Funding through DOEHEP Award DESC0010301, NSF Award PHY1414681, NSF GRFP program. Manuscript authored by UT-Battelle, LLC, under Contract No. DEAC0500OR22725 with the U.S. Department of Energy.
Invited talk: Design of accelerator lattices with nonlinear optics to suppress transverse resonances is a novel approach and may be crucial for enabling low-loss high-intensity beam transport. Large amplitude-dependent tune spreads, driven by nonlinear field inserts, damp resonant response to driving terms. This presentation will focus on simulations of the UMER lattice operated as a quasi-integrable system (1 invariant of transverse motion) with a single strong octupole insert. We will discuss the evolution of simulation models, including the observation of losses associated with the original operating point near a fourth-order resonance. Other operating points farther from this resonance are considered and shown to be more promising.

Slides TUPAG10 [3.447 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG10

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paper received ※ 19 October 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019

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TUPAG11

ESS Accelerator Lattice Design Studies and Automatic Synoptic Deployment

285

Y. Levinsen, R. De Prisco, M. Eshraqi, T.J. Grandsaert, A. Jansson, H. Kocevar, Ø. Midttun, N. Milas, R. Miyamoto, D.C. Plostinar, A. Ponton, T.J. Shea
ESS, Lund, Sweden
H.D. Thomsen
AU, Aarhus, Denmark

The European Spallation Source (ESS) is currently under construction in the south of Sweden. A highly brilliant neutron source with a 5 MW proton driver will provide state of the art experimental facilities for neutron science. A peak proton beam power in the accelerator of 125 MW means that excellent control over the beam losses becomes essential. The beam physics design of the ESS accelerator is in a TraceWin format, for which we have developed revision control setup, automated regression analysis and deployment of synoptic viewer and tabulated spreadsheets. This allows for an integrated representation of the data that are always kept synchronized and available to other engineering disciplines. The design of the accelerator lattice has gone through several major and minor iterations which are all carefully analysed. In this contribution we present the status of the latest studies which is the first time a complete end-to-end study beginning from the ion source has been performed.

Slides TUPAG11 [7.733 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG11

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paper received ※ 18 October 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019

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TUPAG13

S-Based Macro-Particle Spectral Algorithm for an Electron Gun

290

P. M. Jung, T. Planche
TRIUMF, Vancouver, Canada

We derive a Hamiltonian description of a continuous particle distribution and its electrostatic potential from the Low Lagrangian. The self consistent space charge potential is discretized according to the spectral Galerkin approximation. The particle distribution is discretized using macro-particles. We choose a set of initial and boundary conditions to model the TRIUMF 300keV thermionic DC electron gun. The field modes and macro-particle coordinates are integrated self-consistently. The current status of the implementation is discussed.

Slides TUPAG13 [1.335 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAG13

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paper received ※ 01 November 2018 paper accepted ※ 10 December 2018 issue date ※ 26 January 2019

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WEPAF02

Simulations of Beam Chopping for Potential Upgrades of the SNS LEBT Chopper

325

B. Han, S.N. Murray, T.R. Pennisi, V.V. Peplov, M.P. Stockli, R.F. Welton
ORNL, Oak Ridge, Tennessee, USA
R.B. Saethre, C. Stinson
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work was performed at Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, under contract number DE-AC05-00OR22725 for the United States Department of Energy.
The LEBT chopper is a critical element of the SNS accelerator system. In this work, the benefit of increasing the chopping voltage amplitude for the present chopping pattern is shown with beam simulations, and an ongoing hardware upgrade of the chopper pulser units is discussed. In addition, with the prospect of higher voltage capability of the new pulser design, two alternative chopping patterns which reduce the switching frequency of the chopper pulsers down to 1/2 or 1/4 of the present chopping pattern, are also explored with beam simulations.

Slides WEPAF02 [7.431 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPAF02

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paper received ※ 31 October 2018 paper accepted ※ 07 December 2018 issue date ※ 26 January 2019

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WEPAF03

Magnetized Electron Cooling Simulations for JLEIC

I.V. Pogorelov, D.T. Abell, D.L. Bruhwiler, J.A. Carlsson, Y.I. Eidelman, C.C. Hall, S.D. Webb
RadiaSoft LLC, Boulder, Colorado, USA
J. Gerity, P.M. McIntyre
Texas A&M University, College Station, USA
H. Zhang, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: This work is supported by the U.S. DOE Office of Science, Office of Nuclear Physics, under Award Number DE-SC0015212.
Relativistic magnetized electron cooling in untested parameter regimes is essential to achieve the ion luminosity requirements of proposed electron-ion collider (EIC) designs. Therefore, accurate calculations of magnetized dynamic friction are required, with the ability to include all relevant physics that might increase the cooling time, including space charge forces, field errors and complicated phase space distributions of imperfectly magnetized electron beams. We present simulations relevant to the JLEIC design, using the BETACOOL and JSPEC codes. We also present recent work on Warp simulations of the electron beam through the solenoid field. Space charge neutralization is provided by impact ionization of a background hydrogen gas. For optimal cooling it is essential that space charge be sufficiently neutralized. We also present recent work on a new analytic treatment of momentum transfer from a single magnetized electron to a drifting ion, and its use for calculations of dynamic friction.

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WEPLG01

Analysis of Emittance Growth in a Gridless Spectral Poisson Solver for Fully Symplectic Multiparticle Tracking

335

C.E. Mitchell, J. Qiang
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Gridless spectral methods for self-consistent symplectic space charge modeling possess several advantages over traditional momentum-conserving particle-in-cell methods, including the absence of numerical grid heating and the presence of an underlying multi-particle Hamiltonian. Nevertheless, evidence of collisional particle noise remains. For a class of such 1D and 2D algorithms, we provide analytical models of the numerical field error, the optimal choice of spectral modes, and the numerical emittance growth per timestep. We compare these results with the emittance growth models of Struckmeier, Hoffman, Kesting, and others.

Slides WEPLG01 [11.804 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPLG01

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paper received ※ 18 October 2018 paper accepted ※ 28 January 2019 issue date ※ 26 January 2019

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WEPLG02

REPTIL - A Relativistic 3D Space Charge Particle Tracking Code Based on the Fast Multipole Method

S. A. Schmid, H. De Gersem, E. Gjonaj
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: This work is supported by the DFG in the framework of GRK 2128.
Modern free electron lasers and high current energy recovery linacs accelerate electron beams with particle bunch charges reaching up to several nanocoulombs. Especially in the low energy sections, such as the photoinjector of the accelerator, space charge interaction forces are the dominating effect influencing the dynamics of the electron beam. A direct computation of space charge forces is numerically very expensive. Commonly used simulation codes typically apply mesh based particle-in-cell methods (PIC) to solve this problem. Our simulation tool, REPTIL, is a relativistic, three-dimensional space charge tracking code, which computes the interaction forces based on a meshless fast multipole method (FMM). The FMM based space charge solver is more flexible regarding the choice of the interaction model and yields maximum accuracy for the near field forces between particles. For this reason, the FMM is very suitable for the simulation of the influence of space charge on the particle emission process in high current photoinjectors. In this contribution, we present a numerical study of the efficiency and the accuracy of the method. Therefore, we perform a case study for the PITZ photoinjector used for the European XFEL at DESY. Furthermore, we compare the performance of REPTIL with commonly used PIC codes like e.g. ASTRA. Finally, we investigate a hybrid approach by using the FMM on a mesh. The latter method makes further increases in the particle number possible, which translates to a higher resolution in the phase space of the electron bunch.

Slides WEPLG02 [2.443 MB]

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