THPAB —  Posters Thursday 1   (18-May-17   16:00—18:00)

Paper	Title	Page
THPAB001	Microbunching Instability as a Caustic Phenomenon	3676
SUSPSIK053	use link to see paper's listing under its alternate paper code
	T.K. Charles, D.M. Paganin Monash University, Faculty of Science, Clayton, Victoria, Australia M.J. Boland The University of Melbourne, Melbourne, Victoria, Australia M.J. Boland, R.T. Dowd SLSA, Clayton, Australia
	Microbunching instability if left alone, threatens to degrade the beam quality of high brightness electron beams in Free Electron Lasers. Recently, caustic formation in electron trajectories was identified as a mechanism describing current modulations in accelerated particle beams. Here we consider CSR-induced microbunching as a caustic phenomenon. This analysis reports on the influence of longitudinal dispersion, R56, on the microbunching process, as well as elucidating the influence of the second and third order longitudinal dispersion values, T566 and U5666.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB001
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THPAB002	Update of the Collective Effects Studies for Sirius	3680
	F.H. de Sá, H.O.C. Duarte, L. Liupresenter LNLS, Campinas, Brazil
	An updated impedance budget for Sirius, with contributions from 3D electromagnetic simulations and analytic calculations, is presented and the estimates for single and multi-bunch instability thresholds for the first operation phase are re-evaluated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB002
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THPAB003	Harmonic RF System for the ESRF EBS	3684
	N. Carmignani, J. Jacob, B. Nash, S.M. White ESRF, Grenoble, France
	A harmonic RF system for bunch lengthening to increase the Touschek lifetime of the ESRF Extemely Brilliant Source (EBS) is under study. Multiparticle simulations have been performed to study the bunch lengthening and the bunch shape with impedance effect and with third or fourth harmonic cavities. The effect of a harmonic RF system on the microwave instability is studied, finding an increase in the threshold. The AC Robinson instability threshold with a superconducting harmonic cavity has been studied with multiparticle simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB003
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THPAB005	Improvement of the Analytic Vlasov Solver DELPHI	3688
	D. Amorim Université Grenoble Alpes, Grenoble, France N. Biancacci, K.S.B. Li, E. Métralpresenter CERN, Geneva, Switzerland
	The simulation code DELPHI is an analytic Vlasov solver which allows to evaluate the beam transverse stability with respect to impedance effects. It allows to perform fast scans over parameters such as chromaticity, damper gain or beam intensity for a given impedance model and particle distribution. In order to improve the simulation code, new longitudinal particle distributions have been implemented. The simulations results obtained with these distributions are compared to theoretical predictions. An additional post-processing of DELPHI's output has also been implemented, allowing to reconstruct the signal seen by head-tail stripline monitors, in particular in presence of bunch-by-bunch damper. The results are compared to theoretical models, to pyHEADTAIL simulations and to measurements performed in the LHC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB005
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THPAB006	Nuage, Ion Cloud Tracker	3692
SUSPSIK054	use link to see paper's listing under its alternate paper code
	A. Gamelin, C. Bruni, D. Radevych LAL, Orsay, France
	Funding: Work is supported by ANR-10-EQPX-51, by grants from Région Ile-de- France, IN2P3 and Pheniics Doctoral School. NUAGE is a data parallel Matlab code which simulates the ion cloud effect in electron storage rings. The ion cloud is tracked in the ring taking into account the transverse and longitudinal effect of the beam-ion interaction, tracking in magnetic elements, usage of electrodes and gaps as clearing means. This program has been used to compute ionised ion equilibrium state and its neutralisation factor. In this article the NUAGE code is presented. The model, analysis method and performances are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB006
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THPAB007	Short Bunches at the Transition From Strong to Weak Longitudinal Instability	3696
	P. Kuske HZB, Berlin, Germany
	The interaction of particles with their vacuum sur-roundings can lead to longitudinal instabilities of the whole bunch of particles. Most of these instabilities are strong and the growth rates are large compared to the damping rate. For a weak instability the opposite is true and with just a resistive impedance the instability would always be weak and independent of the bunch length. The interaction of a bunch with its own radiation emitted midway between parallel plates leads to a strong instabil-ity for long bunches and a transition to weak instability if the bunch length becomes shorter. This regime is ana-lysed numerically with a Vlasov-Fokker-Planck solver. The results are compared to recent observations at ANKA. An attempt is made to explain the remaining discrepan-cies by including higher order terms of the momentum compaction factor into these calculations. There are indi-cations that the simple model needs refinements in order to take radiation from upstream dipoles into account.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB007
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THPAB008	Particle Swarm Optimization Algorithm Applied in Online Commissioning at the MLS and BESSY II	3700
	J. Li, J. Feikes, P. Goslawski, M. Ries HZB, Berlin, Germany
	Particle Swarm Optimization (PSO) is a population based optimization technique inspired by the social behaviour of bird flocking. This algorithm has been successfully used for beam dynamics simulation due to its excellent capability to deal with large-dimensional optimization problems. At the MLS and BESSY II PSO was first successfully applied to improve the lifetime by 20~30% within only 10 iterations respectively. Now the PSO has been implemented as a multifunctional online optimizer to improve the machine performance. This paper presents some results of online experiments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB008
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THPAB009	Multi-Objective Optimization of an SRF Photoinjector for ERL and UED Applications	3704
SUSPSIK065	use link to see paper's listing under its alternate paper code
	E. Panofski, A. Jankowiak, T. Kamps, G. Kourkafas HZB, Berlin, Germany S. Eisebitt MBI, Berlin, Germany
	Superconducting RF photoinjectors, running in continuous-wave (cw) mode, are able to generate electron beams of high average brightness and ultra-short bunches. Therefore, they satisfy the requirements of future accelerator facilities, such as energy recovery linacs (ERL). Further, SRF guns are able to provide relativistic probe beams for ultrafast electron diffraction (UED). Choosing suitable values for the drive laser, cavity and solenoid settings poses a great challenge for the injector commissioning and operation. Using multi-objective optimization based on an evolutionary algorithm, optimum gun parameter settings are extracted from Pareto-optimum solutions. The development of a universal multi-objective optimization algorithm for SRF photoinjectors as well as first Pareto optimum results for an ERL and UED application of GunLab, the compact SRF gun test facility at Helmholtz-Zentrum Berlin, will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB009
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THPAB011	Optimization of Multicell Microwave Cavities Using YACS	3708
	B.D. Isbarn, B. Riemann, M. Sommer, T. Weis DELTA, Dortmund, Germany
	Funding: Work supported by the BMBF under contract no. 05K13PEB. YACS is a 2.5D finite element method solver capable of solving for the full 3D eigenfrequency spectra of resonant axisymmetric structures while reducing the computational problem to a 2D rotation plane. The most recent revision of the code introduced arbitrary order basis functions and curved meshes, for both triangular and quadrilateral unstructured meshes. This led to significant increases in convergence rates. However, due to the utilization of curved meshes and the complex coordinate transformations that are involved, spurious modes were introduced when solving the axisymmetric problem. Although workarounds do exist that circumvent these issues by lowering the likelihood and frequency of spurious modes, linear triangular meshes with higher order basis functions were chosen due to their simplicity and spurious free solutions. In order to support the usage of spline cavities as an alternative parameterization to the well known elliptical cavities, parameter space scans were carried out for non-reentrant spline cavities. In addition a new optimization strategy is presented that exploits the arbitrary polynomial order of Bézier curves by utilizing the degree elevation technique.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB011
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THPAB012	Beam Transport Optimization for Applying an SRF Gun at the ELBE Center	3712
	P.N. Lu, A. Arnold, P. Murcek, J. Teichert, H. Vennekate, R. Xiang HZDR, Dresden, Germany
	An SRF gun at the ELBE center has been operated with a magnesium cathode. Electron beams were produced with a maximum bunch charge of 200 pC and an emit-tance of 7.7 μm. Simulations have been conducted with ASTRA and Elegant for applying the SRF gun to ELBE user experiments, including neutron beam generation, positron beam generation, THz radiation and Compton backscattering experiment. Beam transport has been optimized to solve the best beam performance for these user stations at the bunch charge of 200 pC. Simulation results indicate that the SRF gun is potential to benefit the high bunch charge applications at ELBE.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB012
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THPAB013	A Fast Particle Tracking Tool for the Simulation of Dielectric Laser Accelerators	3716
	F. Mayet, R.W. Aßmann, U. Dorda, W. Kuropka DESY, Hamburg, Germany W. Kuropka, F. Mayet University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Funding: GBMF - Gordon and Betty Moore Foundation In order to simulate the beam dynamics in grating based Dielectric Laser Accelerators (DLA) fully self-consistent PIC codes are usually employed. These codes model the evolution of both the electromagnetic fields inside a laser-driven DLA and the beam phase space very accurately. The main drawback of these codes is that they are computationally very expensive. While the simulation of a single DLA period is feasible with these codes, long multi-period structures cannot be studied without access to HPC clusters. We present a fast particle tracking tool for the simulation of long DLA structures. DLATracker is a parallelized code based on the analytical reconstruction of the in-channel electromagnetic fields and a Boris/Vay-type particle pusher. It computational kernel is written in OpenCL and can run on both CPUs and GPUs. The main code is following a modular approach and is written in Python 2.7. This way the code can be easiliy extended for different use cases. In order to benchmark the code, simulation results are compared to results obtained with the PIC code VSim 7.2.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB013
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THPAB014	An Adaptive Mesh-Based Method for the Efficient Simulation of LSC-Driven Microbunching Gain in FEL Applications	3720
	Ph. Amstutz University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany M. Vogt DESY, Hamburg, Germany
	Electron beams with high peak current as they are required for the operation of free-electron lasers (FELs) are often generated by means of a series of magnetic bunch compressors. In conjunction with a collective coherent force, e.g. longitudinal space-charge (LSC), bunch compressors can possibly cause a wavelength dependent amplification of initial density inhomogeneities, potentially to an extent detrimental to the operation of the FEL. A common model, consisting of LSC, acceleration (kicks), and magnetic chicanes (drift-type maps), is governed by a time-discrete Vlasov-Poisson system. Such systems have been successfully simulated using mesh based representations of the phase space density (PSD) and the method of characteristics for the update step. However, for the irregular and exotic PSDs, prevalent in FEL applications, a homogeneous high resolution discretization on a naive rectangular mesh can be prohibitively wasteful. Here we present an approach based on adaptive tree refinement that addresses the complexity of the PSDs and allows for the efficient simulation of LSC-driven micro-bunching in FELs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB014
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THPAB016	Investigation on the Ion Motion Towards Clearing Electrodes in an Accelerator	3723
	G. Pöplau COMPAEC e.G., Rostock, Germany A. Meseck HZB, Berlin, Germany
	High brightness beams provided by linac-based accelerators require several measures to preserve their high quality and to avoid instabilities, where the mitigation of the impact of residual ions is one of these measures, in particular if high repetition rates are aimed for. Over the last decade three ion-clearing strategies: clearing electrodes, bunch gaps and beam shaking have been applied to counteract the degrading impact of the ions on the electron beam. Currently, their merit as clearing strategies for next generation high brightness accelerators such as energy recovery linacs (ERLs) are under intensive investigations with both simulations and measurements. In this paper, we present numerical studies for the behavior of ions generated by electron bunch passages within the field of electrodes. The objective is to investigate the ion motion towards the electrodes and to study under which circumstances and up to which ratio, equilibrium between ion generation and ion-clearing is established. Hereby several ion species and shapes of electrodes are considered with typical parameters of future high current linacs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB016
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THPAB017	Investigation of High Repetition Rate Femtosecond Electron Diffraction at PITZ	3727
	H.J. Qian, M. Groß, M. Krasilnikov, A. Oppelt, F. Stephan DESY Zeuthen, Zeuthen, Germany
	PITZ is a photoinjector test facility for FLASH and European XFEL, and it has been proposed to be a prototype machine to develop an accelerator based THz/IR source for European XFEL pump-probe experiment. In addition, the machine can also support femtosecond electron diffraction at the same beam repetition rate as European XFEL, which brings XFEL users more flexibility for different experiments. In this paper, a femtosecond electron diffraction scheme based on the PITZ accelerator setup is investigated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB017
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THPAB019	PSPA, a Web Platform for Simulation of Particle Accelerator	3730
	M.E. Biagini, A. Variola INFN/LNF, Frascati (Roma), Italy L. Garnier, H. Guler, C. Helft, G. Le Meur, M. Nicolas, A. Pérus, F. Touze LAL, Orsay, France
	PSPA (Platform for Simulation of Particle Accelerators) is an original web-based interactive simulation platform for designing and modelling particle accelerators created at Laboratoire de l'Accélérateur Linéaire, Orsay. It aims at eventually containing all the tools to make a start-to-end simulation of an accelerator, and make it possible to run interactively several open source simulations codes available worldwide. At the moment, the focus is on electron/positron accelerators. PSPA will optimize the work of accelerator designers by factoring once and for all the tedious, time-consuming and error prone process of translating data formats between the various codes involved in the modelling of a machine, controlling the repeated execution of these models by easily varying some parameter and managing the associated data. Moreover, as a truly innovative feature, it will provide a convenient means for testing different physical models of a given part of a machine. The status of the project is described in this paper, and examples of its application to the ThomX compact Compton backscattering source at LAL are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB019
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THPAB020	Coupling Impedances and Collective Effects for FCC-ee	3734
	E. Belli, M. Migliorati University of Rome La Sapienza, Rome, Italy G. Castorina, B. Spataro, M. Zobov INFN/LNF, Frascati (Roma), Italy A. Novokhatski SLAC, Menlo Park, California, USA S. Persichelli LBNL, Berkeley, California, USA
	A very important issue for the Future Circular Collider (FCC) is represented by collective effects due to the self-induced electromagnetic fields, which, acting back on the beam, could produce dangerous instabilities. In this paper we will focus our work on the FCC electron-positron machine: in particular we will study some important sources of wake fields, their coupling impedances and the impact on the beam dynamics. We will also discuss longitudinal and transverse instability thresholds, both for single bunch and multibunch, and indicate some ways to mitigate such instabilities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB020
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THPAB021	Wake Field and Head-Tail Instability in Beam-Beam Collision with a Large Crossing Angle	3738
	K. Ohmi, D. Zhou KEK, Ibaraki, Japan N. Kuroo UTTAC, Tsukuba, Ibaraki, Japan K. Oide, F. Zimmermann CERN, Geneva, Switzerland
	Head-tail type of coherent beam-beam instability has been seen in a strong-strong beam-beam simulation for collision with a large Piwinski angle σzθ/σx>>1, where θ is a half crossing angle. Beta x* is key parameter for the instability. The instability is not serious for SuperKEKB, but can be seen in phase II commissioning stage. It has a large impact for design of FCC-ee. We introduce wake field due to the beam-beam collision. The wake field gives turn-by-turn correlation of head-tail mode. Head-tail instability caused by the wake field explains that seen in the strong-strong beam-beam simulation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB021
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THPAB022	Ion Instability in SuperKEKB Phase I Commissioning	3741
	K. Ohmi, H. Fukuma, Y. Suetsugu, M. Tobiyama KEK, Ibaraki, Japan
	Ion instability has been observed in SuperKEKB phase I commissioning. Unstable modes, their growth rates, tune shift were measured. Frequency of the unstable modes is slower than theoretical prediction and the growth rate is also slower. We discuss possible model to explain the measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB022
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THPAB023	The Influence of Initial Current Density Distribution on the Emittance Reduction	3744
SUSPSIK062	use link to see paper's listing under its alternate paper code
	H. Yamashita, T. Kii, K. Masuda, K. Nagasaki, T. Nogi, H. Ohgaki, K. Torgasin, H. Zen Kyoto University, Kyoto, Japan
	In this study, the influence of current density distribu-tion on the cathode surface on the beam emittance evolution was investigated. The emittance evolution with different beam profiles (flat-top, peak and hollow distribution) have been compared. The modification of the current profile was shown to affect the axial distance of the point of minimal emittance over wide range. The hollow profile allows extending the axial distance of the point of emittance minimum keeping its value extremely low. Further the parameters of a peak profile, which give the smallest emittance were determined. This work demonstrates the significance of initial current density distribution for the emittance evolution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB023
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THPAB024	Emittance Growth at Charge-Exchanging Multi-Turn Injection in KURRI FFAG	3747
	T. Uesugi, Y. Ishi, Y. Kuriyama, Y. Mori Kyoto University, Research Reactor Institute, Osaka, Japan
	In the fixed field alternating gradient (FFAG) synchrotron in Kyoto university research reactor institute (KURRI), rapid beam loss of factor 100 is observed right after the injection. In the synchrotron, charge-exchanging multi-turn injection is adopted with a stripping foil located on the closed orbit of the injection energy. No bump orbit system is used and the injected beams escape from the foil according to the closed-orbit shift by acceleration. The particles hit the foil many times and that is why the emittance grows up during the injection. In this paper, simulation studies are done to estimate the emittance growth and beam losses. The scattering effect at the foil is modeled by GEANT4.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB024
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THPAB025	Simulation Studies of Transverse Beam Instabilities and Measures Beyond 1 MW Beam Power in the 3-GeV RCS of J-PARC	3750
	P.K. Saha, H. Hotchipresenter, Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The transverse impedance of the extraction kicker magnets is a significant beam instability source in the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex). The systematic simulation studies for beam instability by including the space charge effect has been done by using the ORBIT code. The simulation results are well reproduced in the corresponding measurements. The designed 1 MW beam power has recently been accomplished by keeping sextuple magnets off in order to stabilize the beam by utilizing the large lattice chromaticity throughout the entire acceleration period. The RCS simultaneously delivers extracted beam to the MLF (Material and Life Science Experimental Facility) and the MR (Main Ring). In order to ensure 1 MW beam power at the MLF even when RCS beam sharing to the MR is twice increased as well as when a second target station is constructed at the MLF, a beam power of 1.5 MW has to be realized in the RCS. However, the simulation shows that beyond 1 MW the beam is unstable even if no chromaticity is corrected. A reduction of the kicker impedance by at least a half is required in order to achieve 1.5 MW beam power in the RCS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB025
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THPAB026	Feasibility Analysis of Emittance Preservation During Bunch Compression in the Presence of Coherent Synchrotron Radiation in an Arc	3753
SUSPSIK055	use link to see paper's listing under its alternate paper code
	X.Y. Huang, X. Cui, S. Gu, Y. Jiao, G. Xu IHEP, Beijing, People's Republic of China
	Electron beam with low transverse emittance, short bunch length and high peak current is the basic requirement in modern high-brightness light sources. However, coherent synchrotron radiation (CSR) will dilute the transverse emittance when the electron beams pass through a magnetic bunch compressor and degrade the performance of the machine. In this paper, based on our CSR point-kick analysis, arc compressors with high compression factor in the presence of CSR effect are studied, both periodic and aperiodic arcs are included. Through analytical and numerical research, an easy optics design technique is introduced to minimize the emittance dilution within these compressors. Taking practical considerations into account, the results of periodic and aperiodic arcs are compared.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB026
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THPAB027	Symplectic Multi-Particle Tracking Using Cuda	3756
SUSPSIK066	use link to see paper's listing under its alternate paper code
	Zh.C. Liu IHEP, Beijing, People's Republic of China J. Qiang LBNL, Berkeley, California, USA
	Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and the Ministry of Science and Technology of China under Grant No.2014CB845501. The symplectic tracking model can preserve phase space structure and reduce non-physical effects in long term simulation. Though this model is computationally expensive, it is very suitable for parallelization and can be accelerated significantly by using Graphic Processing Units (GPUs). Using a single GPU, the code achieves a speedup of more than 400 compared with the time on a single CPU core. It also shows good scalability on a GPU cluster at Oak Ridge Leadership Computing Facility. In this paper, we report on the GPU code implement, the performance test on both single-GPU and multi-GPU cluster, and an application of beam dynamics simulation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB027
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THPAB029	Simulation of the Single Bunch Instabilities for the High Energy Photon Source	3760
	Z. Duan, N. Wang, H.S. Xu IHEP, Beijing, People's Republic of China
	Funding: Work supported by Natural Science Foundation of China (No.11605212). Timing modes pursing a large single bunch charge will be important operation modes for the green-field High Energy Photon Source (HEPS). The single bunch instabilities are simulated with the elegant tracking code, based on the current impedance budget. In particular, a novel on-axis accumulation scheme* based on the RF gymnastics of an active double-RF system was proposed as a candidate injection scheme for HEPS, while the zero-current rms bunch length dramatically decreases during the injection, from 32 mm to 3 mm, over a time duration of about 200 ms. The single bunch instabilities are evaluated for both the operation mode with optimal bunch lengthening as well as the injection mode with the very short bunch length, as a first step in understanding the possible beam instability for this injection scheme. * G. Xu, et al., in Proc. IPAC'16, pp. 2886-2888. Z. Duan, et al., in Proc. eeFACT 2016.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB029
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THPAB030	Studies on Collective Instabilities in HEPS	3763
	N. Wang, Z. Duan, C. Li, S.K. Tian, H.S. Xu IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is a new designed photon source at beam energy of 6 GeV. Due to the small beam size and increased coupling impedance with the restricted beam pipe aperture, the collective effects may bring new challenges to the physical design of the machine. The collective instabilities are estimated for different operation mode. The critical instability issues are also identified for each mode.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB030
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THPAB031	Study of Beam Break Up in Irradiation Linacs	3767
SUSPSIK056	use link to see paper's listing under its alternate paper code
	X.C. Meng, H.B. Chen, W. Gai, J. Shi, S.X. Zheng TUB, Beijing, People's Republic of China G.H. Li, J.S. Liu, Y.H. Liu NUCTECH, Beijing, People's Republic of China F.H. de Sá LNLS, Campinas, Brazil
	Many recent experiments of the irradiation linacs produced at Tsinghua University indicate that beam power is limited by beam break up (BBU). Limits exist while the beam current or the pulse width is increased. In this paper, we illustrate the bream break up (BBU) phenomenon in the cases of both the 10MeV travelling-wave linac and 10MeV backward travelling-wave linac. The higher order modes in the linacs are analysed and the wake fields are calculated both with theoretical analysis and numerical simulation. Also, the beam dynamics is studied on the basis of the wakefield results to find a BBU threshold in these structures.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB031
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THPAB032	Estimates of Collective Effects in the HALS Storage Ring Having the First Version Lattice	3770
SUSPSIK057	use link to see paper's listing under its alternate paper code
	N. Hu, Z.H. Bai, W. Li, Q. Luo, L. Wang USTC/NSRL, Hefei, Anhui, People's Republic of China
	The Hefei Advanced Light Source (HALS) is a diffraction-limited storage ring with a beam energy of 2.0 GeV. Recently the first version lattice has been designed for the HALS storage ring, and the natural emittance is about 18 pm·rad. In this paper, we study the collective effects in this storage ring, including calculations of intra-beam scattering effect and Touschek lifetime, and estimates of the thresholds of some single-bunch and multi-bunch instabilities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB032
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THPAB034	Generation of Short Intense Heavy-Ion Pulses in HIAF	3774
	D.Y. Yin, H. Du, L.J. Mao, G.D. Shen, J.W. Xia, J.C. Yang IMP/CAS, Lanzhou, People's Republic of China
	The HIAF is a new accelerator complex under design at IMP to provide intense primary and radioactive ion beams for nuclear physics, atomic physics, high energy density physics and other applications. As a key part of HIAF, the Booster Ring (BRing) is designed to accumulate and accelerate heavy ion beams provided by iLinac up to high intensity and energy. The high quality, well focused, strongly bunched intense Uranium beam (U34+) with high energy and high intensity of 1011 will open a new area for the HED physics research in laboratory. Based on the beam parameters of 238U34+ proposed by the BRing, the two critical issues of producing short bunch with high beam intensity are studied. One is efficiency of adiabatic capture which can be a necessary prerequisite to ensure the beam intensity, and the other one is bunch compression in longitudinal which is an effective way of producing short pulse duration bunch. In this article, the analytical calculations and tracking simulations are described, the capture efficiency and possible bunch length under the action of planning RF system are presented
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB034
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THPAB035	Central Region Design of the Hust SCC250 Superconducting Cyclotron	3778
	L.X.F. Li Private Address, Wuhan, People's Republic of China K.J. Kuanjun, M.Z. Mei, Z.J. Zeng, L.G. Zhang HUST, Wuhan, People's Republic of China
	Recently, the development of a 250 MeV cyclotron for advanced cancer therapy has been carried out by Huazhong University of Science and Technology(HUST) . It has four sector magnet and RF cavity which resonance frequency is 74.69 MHz. The internal ion source was adopted and the central region was designed to accommodate the starting beam. In this paper, the design of the central region to optimize the initial circumstances for H¬+ beam were described. The electric and magnetic field distribution were designed by electrostatic and magnetic solver in OPERA-3D TOSCA. The beam characteristics including the beam orbit, motion of the center of orbit, energy gain was investigated for central region was simulated by means of computer code Z3CYCLONE.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB035
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THPAB036	An Experimental Study of Beam Dynamics in the ERL-Based Novosibirsk Free Electron Laser	3781
	V.M. Borin, L.M. Schegolev, O.A. Shevchenko, N.A. Vinokurov BINP SB RAS, Novosibirsk, Russia V.L. Dorokhov, O.I. Meshkov BINP, Novosibirsk, Russia
	Transverse and longitudinal dynamics of the electron beam of the Novosibirsk infrared Free Electron Laser is studied. The Novosibirsk FEL is based on the multi-turn energy recovery linac (ERL). The ERL operate in CW mode with an average current about 10 mA. Therefore non-destructive beam diagnostics is preferable. The beam energy at the last track of the ERL is 42 MeV. As a result, significant part of synchrotron radiation from bending magnets is in the visible range. The transverse beam dimensions were measured with the optical diagnostics before and after the undulator applied for generation of middle-infrared coherent radiation. The obtained data is used to calculate the beam energy spread and emittance. The longitudinal beam dynamics was studied with electro-optical dissector.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB036
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THPAB038	DYNAC: Extensions, Updates, and Upgrades	3784
	S. Molloy, E. Tanke ESS, Lund, Sweden
	DYNAC is a multi-particle beamline simulation code suitable for modelling of the motion of protons, heavy ions, or electrons, moving through linear accelerators and beam transport lines. In this paper, we document extensions written in Python. It will be shown how these Python extensions add a considerable amount of flexibility to DYNAC, while maintaining the calculation speeds available from the core Fortran source. Real-world use-cases are discussed. In addition, some improvements that have been made to the DYNAC source are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB038
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THPAB039	Novel Manufacturing Concepts for 12 GHz High Gradient Accelerating Structures	3787
	A. Solodko, S. Atieh, N. Catalán Lasheras, A. Grudiev, S. Lebet, W. Wuensch CERN, Geneva, Switzerland H. Zha TUB, Beijing, People's Republic of China
	CLIC high gradient accelerating structures (AS) work-ing in X-band are made of copper ultra-high precision discs, requiring both milling and turning operations. Discs are then joint together by diffusion bonding. The rest of important technical systems, such as vacuum, cooling and manifolds, to house damping silicon carbide absorbers, are brazed to the bonded disc stack afterwards. This manufacturing technique has been successfully demonstrated but it is very challenging and needs an accurate assembly at every production step. Main issues concern vacuum-tightness, misalignment, deformations during different assembly operations, defects of braz-ing/bonding operations (gaps, a leak of brazing material) etc. Preparation and repairs are time and resource con-suming and increase the final price of the accelerating structure. This paper describes the novel manufacturing concepts for 12 GHz high gradient AS and focuses on new joining techniques as electron beam welding or brazing, new engineering solutions, as rectangular cells or structures made of halves are being considered.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB039
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THPAB040	Destabilising Effect of Linear Coupling in the LHC	3791
	L.R. Carver, D. Amorim, N. Biancacci, X. Buffat, K.S.B. Li, E. Métral, B. Salvant, M. Schenk CERN, Geneva, Switzerland
	During operation in 2015 and 2016, some transverse instabilities were observed when either the coupling (or closest tune approach) C- was large, or when the tunes were moved closer together. This motivated a campaign of simulations on the effect of linear coupling on the transverse stability. Measurements made during operation and with dedicated beam time have been found to confirm the predictions. This paper will detail the results of the linear coupling studies and relate them to operation of the LHC in the future.
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THPAB041	Implementation of Hollow Electron Lenses in SixTrack and First Simulation Results for the HL-LHC	3795
	M. Fitterer, R. De Maria, S. Redaelli, K.N. Sjobak, J.F. Wagner CERN, Geneva, Switzerland G. Stancari, A. Valishev Fermilab, Batavia, Illinois, USA
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy. Electron lenses have found a wide range of applications for hadron colliders, where the main applications are machine protection and beam-beam compensation. This paper summarizes the status of the current electron lens implementation in SixTrack with the focus on hollow electron beams for beam collimation and shows some first simulation results of the High-Luminosity upgrade of the LHC (HL-LHC).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB041
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THPAB042	Long-Range Beam-Beam Orbit Effects in LHC, Simulations and Observations From Machine Operation in 2016	3799
	A.A. Gorzawski, K. Fuchsberger, M. Hostettlerpresenter, T. Pieloni, J. Wenninger CERN, Geneva, Switzerland
	To limit the number of head on collisions to only one at the interaction point in the Large Hadron Collider (LHC), two beams are colliding with a non zero crossing angle. Under the presence of such angle the closed orbits of the individual bunches in the bunch train varies due to the long-range beam-beam effects. These variations leave a signature as a non zero transverse offset at the collision points visible in the front and trail of the bunch train. When operation team aims for the optimised beam orbit and therefore maximised luminosity, those front and tail bunches due to the overall offset experience reduced luminosity. This paper describes an overview of the existing tool for simulating these effects and compares to operational data. The effects of different operational scenarios (i.e. beam brightness, reduced or asymmetric crossing angles between the interaction points etc.) are simulated and discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB042
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THPAB043	Evolution of Python Tools for the Simulation of Electron Cloud Effects	3803
	G. Iadarola, E. Belli, K.S.B. Li, L. Mether, A. Romanopresenter, G. Rumolo CERN, Geneva, Switzerland
	PyECLOUD was originally developed as a tool for the simulation of electron cloud build-up in particle accelerators. Over the last five years the code has become part of a wider set of modular and scriptable python tools that can be combined to study different effects of the e-cloud in increasingly complex scenarios. The Particle In Cell solver originally included in PyECLOUD later developed into a stand-alone general purpose library (PyPIC) that now includes advanced features like a refined modeling of curved boundaries and optimized resolution based on the usage of nested grids. The effects of the e-cloud on the beam dynamics can be simulated interfacing PyECLOUD with the PyHEADTAIL code. These simulations can be computationally very demanding due to the multi-scale nature of this kind of problems. Hence, a dedicated parallelization layer (PyPARIS) has been recently developed to profit of parallel computing resources in order to significantly speed-up the computation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB043
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THPAB044	Development of Computational Tools for Noise Studies in the LHC	3807
SUSPSIK067	use link to see paper's listing under its alternate paper code
	S. Kostoglou, N. Karastathis, Y. Papaphilippou, D. Pellegrini, P. Zisopoulos CERN, Geneva, Switzerland P. Zisopoulos Uppsala University, Uppsala, Sweden
	Noise can have a significant impact on the beam dynamics in the LHC, enhancing diffusion processes and leading to emittance blowup. In order to study the details of such effects with computer simulations, a new set of tools is being developed. In particular, a demonstrator GPU-based particle tracker has been built profiting from the technology provided by the NVRTC Cuda library. Its performances for short term beam dynamic simulations in presence of many macro particles are highly promising. In addition, the Numerical Analysis of Fundamental Frequencies (NAFF) algorithm has been thoroughly inspected. Several alternatives to its fundamental steps have been investigated in a modern C++ implementation. The method was also used to produce Frequency Maps and benchmark these tools with other simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB044
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THPAB046	SixTrack for Cleaning Studies: 2017 Updates	3811
	A. Mereghetti, R. Bruce, F. Cerutti, R. De Maria, A. Ferrari, M. Fiascaris, P.D. Hermes, D. Mirarchi, P.G. Ortega, D. Pastor Sinuela, E. Quaranta, S. Redaelli, K.N. Sjobak, V. Vlachoudis CERN, Geneva, Switzerland J. Molson LAL, Orsay, France Y. Zou IHEP, Beijing, People's Republic of China
	SixTrack is a single particle tracking code for simulating beam dynamics in ultra-relativistic accelerators. It is widely used at the European Organisation for Nuclear Research (CERN) for predicting dynamic aperture and cleaning inefficiency in large circular machines like the Super Proton Synchrotron (SPS), the Large Hadron Collider (LHC) and the Future Circular Collider (FCC). The code is under continuous development, to both extend its physics models, and enhance performance. The present work gives an overview of developments, specifically aimed at extending the code capabilities for cleaning studies. They mainly involve: the online aperture check; the possibility to perform simulations coupled to advanced Monte Carlo codes like Fluka or using the scattering event generator of the Merlin code; the generalisation of tracking maps to ion species; the implementation of composite materials of relevance for the future upgrades of the LHC collimators; the physics of interactions with bent crystals. Plans to merge these functionalities into a single version of the SixTrack code will be outlined.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB046
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THPAB047	New Features of the 2017 SixTrack Release	3815
	K.N. Sjobak, J. Barranco García, R. De Maria, E. McIntosh, A. Mereghettipresenter CERN, Geneva, Switzerland M. Fitterer Fermilab, Batavia, Illinois, USA V. Gupta IIT, Guwahati, Assam, India J. Molson LAL, Orsay, France
	The SixTrack particle tracking code is routinely used to simulate particle trajectories in high energy circular machines like the LHC and FCC, and is deployed for massive simulation campaigns on CERN clusters and on the BOINC platform within the LHC@Home volunteering computing project. The 2017 release brings many upgrades that improve flexibility, performance, and accuracy. This paper describes the new modules for wire- and electron lenses (WIRE and ELEN), the expert interface for beam-beam element (BEAM/EXPERT), the extension of the number of simultaneously tracked particles, the new Frequency Map Analysis (FMA) postprocessing option, the generation of a single zip of selected output files (ZIPF) in order to extend the coverage of the studies in LHC@HOME (e.g. FMA and on-line aperture checks), coupling to external codes (DYNK-PIPE and BDEX), a new CMAKE based build- and test mechanism, and internal restructuring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB047
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THPAB049	Progress in the Understanding of the Performance Limitations in the CERN Low Energy Ion Ring	3819
	A. Huschauer, H. Bartosik, S. Hancock, V. Kain CERN, Geneva, Switzerland
	The performance of heavy ion beams in the CERN Low Energy Ion Ring is mainly limited by beam loss occuring during the radio-frequency capture and the first part of acceleration. Since October 2015, the driving mechanism of these losses has been studied in detail and an interplay of direct space charge forces and excited betatron resonances was identified as the most plausible explanation of the phenomenon. In this paper we summarize the current understanding of the loss mechanism by presenting recent experimental and simulation studies. We discuss strategies to mitigate beam loss and further improve the performance of the accelerator in the future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB049
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THPAB050	Simulations of Beam-Beam Interactions With RF-Track for the AWAKE Primary Beam Lines	3823
	J.S. Schmidt, A. Latina CERN, Geneva, Switzerland
	The AWAKE project at CERN will use a high-energy proton beam at 400 GeV/c to drive wake'elds in a plasma. The amplitude of these wake'elds will be probed by injecting into the plasma a low-energy electron beam (10-20 MeV/c), which will be accelerated to several GeV. Upstream of the plasma cell the two beams will either be transported coaxially or with an o'set of few millimetres for about 6 m. The interaction between the two beams in this beam line has been investigated in the past, with a dedicated simulation code tracking particles under the in'uence of direct space-charge e'ects. These simulations have recently been crosschecked with a new simulation code called RF-Track, developed at CERN to simulate low energy accelerators. RF-Track can track multiple-specie beams at arbitrary energies, taking into account the full electromagnetic particle-to-particle inter-action. For its characteristics RF-Track seems an ideal tool to study the AWAKE two-beam interaction. The results of these studies are presented in this paper and compared to the previous results. The implications for the facility performance are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB050
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THPAB051	A GPU Variant of Mbtrack and Its Application in SLS-2	3827
	U. Locans, A. Adelmann, L. Stingelin, H.S. Xu PSI, Villigen PSI, Switzerland U. Locans University of Latvia, Riga, Latvia
	Mbtrack is a widely used multi-bunch tracking code, developed at SOLEIL, for modeling the collective instabilities in electron storage rings. It has been applied to the Swiss Light Source upgrade proposal (SLS-2) for the study of single bunch instabilities. However, an n-bunch simulation using mbtrack requires to run n+1 MPI processes. Therefore, a large scale computing cluster may be necessary to perform the simulation. In order to reduce the demands of computing resources for multi-bunch simulations, a CUDA version of mbtrack has been developed, in which the computations of mbtrack are offloaded to a graphics processing unit (GPU). With the mbtrack-cuda variant, multi-bunch simulations can now run in a standalone workstation equipped with an Nvidia graphics card for scientific computing. The implementation and benchmark of the mbtrack-cuda code together with the applications in the study of longitudinal instabilities for SLS-2 will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB051
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THPAB052	Recent Developments in DEMIRCI, the RFQ Design Software	3830
	E. Celebi Bogazici University, Bebek / Istanbul, Turkey O. Cakir, G. Turemen, B. Yasatekin Ankara University, Faculty of Sciences, Ankara, Turkey G. Turemen, B. Yasatekin TAEK - SANAEM, Ankara, Turkey G. Unel UCI, Irvine, California, USA
	Funding: This project has been supported by TUBITAK with project number 114F106. The RFQ design tool DEMIRCI aims to provide fast and accurate simulation of a light ion accelerating cavity and of the ion beam in it. It is a modern tool with a graphical user interface leading to a point and click method to help the designer. This article summarizes the recent developments of DEMIRCI software such as the addition of beam dynamics and 8-term potential coefficient calculations. Its results are compared to other software available on the market, to show the attained compatibility level. Finally the future prospects are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB052
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THPAB053	Laser Heater Deisgn for the CLARA FEL Test Facility	3833
	A.D. Brynes, S.P. Jamison, B.D. Muratoripresenter, N. Thompson, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom S.P. Jamison, B.D. Muratoripresenter, N. Thompson, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom
	We present considerations of microbunching studies in the CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility under construction at Daresbury Laboratory. CLARA, a high-brightness electron linac, presents an opportunity to study the microbunching instability. A number of theoretical models have been proposed concerning the causes of this instability, and it has also been observed at various FEL facilities. We have applied these models to the CLARA FEL, and propose a suitable laser heater design which will provide flexibility in terms of the range of modes of operation for CLARA. We also propose a method for inducing and controlling the microbunching instability via pulse stacking of the photoinjector laser.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB053
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THPAB055	Modelling of Curvilinear Electrostatic Multipoles in the Fermilab Muon g-2 Storage Ring	3837
SUSPSIK068	use link to see paper's listing under its alternate paper code
	A.T. Herrod, S. Jones, A. Wolski The University of Liverpool, Liverpool, United Kingdom I.R. Bailey, A.T. Herrod, S. Jones, M. Korostelev, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom I.R. Bailey, M. Korostelev Lancaster University, Lancaster, United Kingdom
	Funding: This research was funded by the STFC Cockcroft Institute Core grants no. ST/G008248/1 and ST/P002056/1. The Fermilab Muon g-2 Experiment (E989) contains flat-plate electrostatic quadrupoles, curved with the reference trajectory as defined by the constant, uniform magnetic dipole field. To understand the beam behaviour at a sufficient level, we require fast, high-accuracy particle tracking methods for this layout. Standard multipole fits to numerically calculated 2D transverse electric field maps have provided a first approximation to the electric field within the main part of the quadrupole, but cannot model the longitudinal curvature or extended fringe fields of the electrostatic plates. Expressions for curvilinear multipoles can be fit to a 2D transverse slice taken from the central point of a numerically calculated 3D electric field map of the quadrupole, providing a curved-multipole description. Generalised gradients can be used to model the fringe field regions. We present the results of curvilinear multipole and generalised gradient fits to the curved quadrupole fields, and the differences in tracking using these fields over 200 turns of a model of the storage ring in BMAD.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB055
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THPAB056	Dynamic Aperture Studies of the Long-Range Beam-Beam Interaction at the LHC	3840
	M.P. Crouch, R.B. Appleby UMAN, Manchester, United Kingdom J. Barranco García, T. Pielonipresenter, C. Tambasco EPFL, Lausanne, Switzerland X. Buffat, M. Giovannozzi, E.H. Maclean CERN, Geneva, Switzerland B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Long-range beam-beam interactions dictate the choice of operational parameters for the LHC, such as the crossing angle and β* and therefore the luminosity reach for the collider. These effects can lead to particle losses, closed orbit effects and emittance growth. Defining how these effects depend on the beam-beam separation will determine the minimum crossing angle and the β* the LHC can operate. In this article, analysis from a dedicated machine study is presented in which the crossing angle was reduced in steps and the impact on beam intensity and luminosity lifetimes were observed. Based on the observations during the machine study, the intensity decays are compared to expectations from models. Estimates of the luminosity reach in the LHC are also computed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB056
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THPAB057	Method to Calculate the Longitudinal Impedance From a Partial Wakefield Simulation	3844
	N.C. Shipman UMAN, Manchester, United Kingdom G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom R. Calaga CERN, Geneva, Switzerland J.A. Mitchell Lancaster University, Lancaster, United Kingdom
	When simulating modes with high Q-factors, the wakefield length necessary to calculate the impedance spectrum can often mean a computation time of several weeks or more. A method has been developed which enables the longitudinal impedance and Q-factors of multiple modes to be calculated from a partially decayed wakefield simulation. This paper presents an overview of the method along with preliminary, proof of principle, results showing that considerable simulation time can be saved whilst maintaining a good degree of accuracy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB057
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THPAB058	PyZgoubi Simulations of the CBETA Lattice	3847
	S.C. Tygier UMAN, Manchester, United Kingdom C.E. Mayes Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA F. Méot, N. Tsoupas BNL, Upton, Long Island, New York, USA
	Funding: Work supported by New York State Energy Research and Development Authority (NYSERDA) The Cornell-BNL Electron Test Accelerator CBETA is a 4 pass up, 4 pass down energy recovery linac using Fixed-Field Alternating-Gradient (FFAG) recirculation arcs with a top energy of 150 MeV. We present lattice implemented in the tracking code pyZgoubi, with both hard edge and field map magnet versions. We also describe the recent developments in pyZgoubi such as importing lattice tables from other tracking codes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB058
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THPAB059	CSR and Space Charge Studies for the CLARA Phase 1 Beamline	3851
	B.S. Kyle, R.B. Appleby UMAN, Manchester, United Kingdom J.K. Jones, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom M.J. de Loos, S.B. van der Geer Pulsar Physics, Eindhoven, The Netherlands
	The installation of Phase 1 of CLARA, the UK's new FEL test facility, is currently underway at Daresbury Laboratory. When completed, it will be able to deliver 45 MeV electron beams to the pre-existing VELA beamline, which runs parallel. Phase 1 consists of a 10 Hz photocathode gun, a 2 m long S-band travelling wave linac, a spectrometer line, and associated optics and diagnostics. A detailed study into the beam dynamics of the lattice is presented, with a focus towards the effects of space charge and coherent synchrotron radiation on the electron bunch. Simulations disagreed with predictions from a one-dimensional model of coherent radiation, and this disagreement is believed to be due to a violation of the Derbenev criterion.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB059
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THPAB060	pyAT: A Python Build of Accelerator Toolbox	3855
	W.A.H. Rogers DLS, Oxfordshire, United Kingdom N. Carmignani, L. Farvacque, B. Nash ESRF, Grenoble, France
	Accelerator Toolbox* (AT) is a particle accelerator modelling tool originally written in MATLAB. It is used at many accelerator facilities, particularly synchrotron light sources, as an on-line model and is also used for off-line beam dynamics studies. For speed of execution, the tracking engine of AT was written in C and compiled for use in MATLAB. The C-based implementation allowed re-use of of the tracking engine compiled against the core Python libraries to create a Python version of AT. For additional purposes of speed, the C interface to the integration routines has been modified allowing equal speeds for both MATLAB and Python interfaces, with an increase in speed relative to the original MATLAB version. This paper describes the adaptation process, including adapting the MATLAB build, creating the Python build and laying the foundations for the additional Python library implementation. Speed benchmarks are included with comparison to other tracking codes Elegant and MADX. * A. Terebilo, Accelerator Toolbox for MATLAB, SLAC-PUB-8732 (2001)
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THPAB061	Limiting Effects in the Double EEX Beamline	3858
	G. Ha POSTECH, Pohang, Kyungbuk, Republic of Korea M.E. Condepresenter, D.S. Doran, J.G. Power ANL, Argonne, Illinois, USA
	Funding: This work is supported by Department of Energy, Office of High Energy Physics, under Contract No. DE-AC02-06CH11357. The double emittance exchange (EEX) beamline is suggested to overcome the large horizontal emittance and transverse jitter issues associated with the single EEX beamline while preserving its powerful phase-space manipulation capability. However, the double EEX beamline also has potential limitations due to coherent synchrotron radiation (CSR) and transverse jitter. The former limitation arises because double EEX uses twice as many bending magnets as single EEX which means stronger CSR effects degrading the beam quality. The latter limitation arises because a longitudinal jitter in front of the first EEX beamline is converted into a transverse jitter in the middle section (between the EEX beamlines) which can cause beam loss or beam degradation. In this paper, we numerically explore the effects of these two limitations on the emittance and beam transport.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB061
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THPAB062	Preliminary Simulations on Chirpless Bunch Compression using Double-EEX Beamline	3862
	G. Ha POSTECH, Pohang, Kyungbuk, Republic of Korea M.E. Condepresenter, D.S. Doran, W. Gai, J.G. Power ANL, Argonne, Illinois, USA
	Funding: This work is supported by Department of Energy, Office of High Energy Physics, under Contract No. DE-AC02-06CH11357. An emittance exchange (EEX) beamline can be used to compress an electron bunch via its transverse-to-longitudinal exchange mechanism. We are investigating this as an alternative to the normal magnetic chicane bunch compressor. The chicane method requires a longitudinal chirp before the chicane (since it relies on the path length difference of different energies) which results in an unwanted chirp after the compressor. Alternatively, the EEX method uses quadrupole magnets to compress the bunch. In this paper, we present preliminary simulations in preparation for a demonstration of chirp-less bunch compression using an EEX beamline at the Argonne Wakefield Accelerator facility.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB062
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THPAB065	A Tool for Small Longitudinal Beam Dynamics in Synchrotrons	3865
	J.-F. Ostiguy, V.A. Lebedev Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy A number of codes are available to simulate longitudinal dynamics in synchrotrons. The most established ones include TIBETAN, LONG1D, ORBIT, and ESME. While they embody a wealth of accumulated wisdom and experience, most of these codes were written decades ago and to some extent they reflect the constraints of their time. As a result, there is interest for updated tools taking better advantage of modern software and hardware capabilities. At Fermilab, the PIP-II project has provided the impetus for development of such a tool. In this contribution, we discuss design decisions and code architecture. A selection of test cases based on an initial prototype are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB065
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THPAB066	Modeling Cathode Roughness, Work Function, and Field Enhancement Effects on Electron Emission	3869
	D.A. Dimitrov, G.I. Bell, D.N. Smithe, S.A. Veitzer Tech-X, Boulder, Colorado, USA I. Ben-Zvi, J. Smedley BNL, Upton, Long Island, New York, USA J. Feng, S.S. Karkare, H.A. Padmore LBNL, Berkeley, California, USA
	Funding: This work is supported by the US DOE Office of Science, department of Basic Energy Sciences under grant DE-SC0013190. Recent developments in material design and growth have resulted in photocathodes that can deliver high quantum efficiency and are sufficiently robust to use in high electric field gradient photoinjectors and free electron lasers. The growth process usually produces photoemissive material layers with rough surface profiles that lead to transverse accelerating fields and possible work function variation resulting in emittance growth. To better understand the effects of surface roughness on emitted electron beams, we have developed realistic three-dimensional models for photocathode materials with grated surface structures. They include general modeling of electron excitation due to photon absorption, charge transport and emission from rough surfaces taking into account image charge and field enhancement effects. We implemented these models in the VSim particle-in-cell code. We report results from simulations using different photocathode materials with grated and flat surfaces to investigate how controlled roughness, work function variation, and field enhancement affect emission properties.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB066
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THPAB072	Application of Voronoi Diagram to Mask-Based Intercepting Phase-Space Measurements	3872
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA Q. Gao, J.G. Power, E.E. Wisniewski ANL, Argonne, Illinois, USA Q. Gao TUB, Beijing, People's Republic of China G. Ha POSTECH, Pohang, Kyungbuk, Republic of Korea P. Piot Fermilab, Batavia, Illinois, USA
	Intercepting multi-aperture masks (e.g. pepper pot or multislit mask) combined with a downstream transverse-density diagnostics (e.g. based on optical transition radiation or employing scintillating media) are commonly used for characterizing the phase space of charged particle beams and the associated emittances. The required data analysis relies on precise calculation of the RMS sizes and positions of the beamlets originated from the mask which drifted up to the analyzing diagnostics. Voronoi diagram is an efficient method for splitting a plane into subsets according to the distances between given vortices. The application of the method to analyze data from pepper pot and multislit mask based measurement is validated via numerical simulation and applied to experimental data acquired at the Argonne Wakefield Accelerator facility. We also discuss the application of the Voronoi diagrams to quantify transversely-modulated beams distortion.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB072
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THPAB073	Magnetized and Flat Beam Experiment at FAST	3876
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA J. Hyun Sokendai, Ibaraki, Japan D. Mihalcea, P. Piot, T. Sen, J.C.T. Thangaraj Fermilab, Batavia, Illinois, USA
	A photocathode, immersed in solenoidal magnetic field, can produce canonical-angular-momentum (CAM) dominated electron beams. Such beams have an application in electron cooling of hadron beams and can also be uncoupled to yield asymmetric-emittance (flat) beams. In the present paper we explore the possibilities of the flat beam generation at Fermilab's Accelerator Science and Technology (FAST) facility linear accelerator. We present optimization of the beam flatness and four-dimensional transverse emittance and investigate the mapping and its limitations of the produced eigen-emittances to conventional emittances using a skew-quadrupole channel. Possible application of flat beams at the FAST facility are also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB073
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THPAB074	MuSim, a Graphical User Interface for Multiple Simulation Programs	3880
	T.J. Roberts, R.J. Abrams, M.A. Cummingspresenter Muons, Inc, Illinois, USA Y. Bao UCR, Riverside, California, USA
	MuSim is a user-friendly program designed to interface to many different particle simulation codes, regardless of their data formats or geometry descriptions. It presents the user with a compelling graphical user interface that includes a flexible 3-D view of the simulated world plus powerful editing and drag-and-drop capabilities. All aspects of the design can be parameterized so that parameter scans and optimizations are easy. It is simple to create plots and display events in the 3-D viewer, allowing for an effortless comparison of different simulation codes. Simulation codes: G4beamline 3.02, MCNP 6.1, and MAD-X; more are coming. Many accelerator design tools and beam optics codes were written long ago, with primitive user interfaces by today's standards. MuSim is specifically designed to make it easy to interface to such codes, providing a common user experience for all, and permitting the construction and exploration of models with very little overhead. For today's technology-driven students, graphical interfaces meet their expectations far better than text-based tools, and education in accelerator physics is one of our primary goals.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB074
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THPAB075	Accelerator Driven Subcritical Reactors for Profitable Disposition of Surplus Weapons-Grade Plutonium and Energy Generation	3883
	M.A. Cummings, R.J. Abramspresenter, R.P. Johnson, T.J. Roberts Muons, Inc, Illinois, USA
	We discuss the GEM*STAR reactor concept, which addresses all historical reactor failures, which includes an internal spallation neutron target and high temperature molten salt fuel with continuous purging of volatile radioactive fission products such that the reactor contains less than a critical mass and almost a million times fewer volatile radioactive fission products than conventional reactors like those at Fukushima. GEM*STAR is a reactor that without redesign will burn spent nuclear fuel, natural uranium, thorium, or surplus weapons material. It will operate without the need for a critical core, fuel enrichment, or reprocessing making it an excellent candidate for export. While conventional nuclear reactors are becoming more and more difficult to license and expensive to build, SRF technology development is on a steep learning curve and the simplicity implied by subcritical operation will lead to reductions in regulatory hurdles and construction complexity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB075
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THPAB076	Coherent Synchrotron Radiation Simulations for Off-Axis Beams Using the Bmad Toolkit	3887
	D. Sagan, C.E. Mayes Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Coherent synchrotron radiation (CSR) potentially limits operation accelerators with high bunch charges and/or short bunch lengths by increasing energy spread, and by Except at the lowest beam energies, the one dimensional treatment of coherent synchrotron radiation (CSR) originally developed by Saldin is an efficient and reasonably accurate way to simulate the effects of CSR on a particle beam. A possible problem with standard implementations of the 1D CSR formalism is that these implementations assume that the beam centroid is close to the reference trajectory that defines the lattice. In this paper, the one dimensional treatment is extended to take into account beams whose centroid is far from the reference trajectory and an example using the Cornell-BNL Fixed Field Alternating Gradient (FFAG) accelerator CBETA is given.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB076
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THPAB077	Opal Simulations of the PSI Ring Cyclotron and a Design for a Higher Order Mode Flat Top Cavity	3891
	N. Pogue LLNL, Livermore, California, USA A. Adelmann, L. Stingelin PSI, Villigen PSI, Switzerland
	Funding: The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/ 2007-2013) under grant agreement n.°290605 (PSI-FELLOW/COFUND). The PSI cyclotron has been producing high power proton beam for 41 years. Over its lifetime it has been upgraded from producing 100 μA to 2.2 mA at 590 MeV. As the power reaches higher levels, it become more important to understand how the machine's beam dynamics will reach to new features of devices introduced. We present an OPAL (Object Oriented Parallel Accelerator Library) model of the cyclotron and compared it to the probe measurements from the machine. This model has good agreement with the measurements over the ~180 revolutions in the machine. Using this same model, a higher order mode flat top cavity was inserted into the machine to illustrate that its design and field structure allowed beam to be extracted. The HOM cavity design will also be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB077
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THPAB078	Beam Dynamics Studies of the Transverse Gradient Undulator and Its Application to Suppression of Microbunching Instability	3895
	T. Liu, Y. Ding, Z. Huangpresenter, W. Qin SLAC, Menlo Park, California, USA T. Liu University of Chinese Academy of Sciences, Beijing, People's Republic of China T. Liu, D. Wang SINAP, Shanghai, People's Republic of China
	A transverse gradient undulator (TGU) which was initially proposed for high gain free electron lasers (FELs) driven by electron beams with relatively large energy spread, can be extended to the application of beam dynamics, such as phase-merging enhanced harmonic generation FEL and suppression of microbunching instability. In this contribution we present beam dynamics studies of the TGU, analyze the resulting focusing and dispersion, and discuss the effects of an additional corrector on the TGU. As an application to beam dynamics, we show a feasible transport system based on the TGU as a reversible electron beam heater to suppress the microbunching instability of the electron beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB078
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THPAB079	Terahertz Chirper for the Bunch Compression of Ultra-Low Emittance Beams	3899
	A.R. Vrielink, A. Marinelli, E.A. Nanni SLAC, Menlo Park, California, USA
	Recent efforts have demonstrated the possibility of achieving ultralow transverse emittance beams for high brightness light sources and free electron lasers*. While these lower emittances should translate to improved lasing efficiency and higher peak brightness in FELs, these beams are commensurately more vulnerable to coherent synchrotron radiation (CSR) for the selfsame reasons. Conserving these ultralow emittances through the bunch compressors in an FEL given their increased propensity to emit CSR is particularly challenging. We investigate the possibility of imposing a large energy chirp at terahertz wavelengths to reduce the required magnetic fields in the compressor, counteracting the ultralow emittance in the generation of CSR. A second, higher frequency THz chirper would then be used to dechirp the beam after the chicane. Operation at THz as opposed to conventional radiofrequencies offers significantly larger chirp at similar input powers, yet still with wavelengths greater than typical FEL bunch lengths (several femtoseconds). Potential experimental schemes will be suggested in the context of LCLS and their feasibility evaluated. * S. Bettoni, M. Pedrozzi and S. Reiche, Phys. Rev. ST Accel. Beams. 18, 123403 (December, 2015).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB079
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THPAB080	Estimations of Coherent Instabilities for JLEIC	3903
	R. Li JLab, Newport News, Virginia, USA
	Funding: Work supported by the Department of Energy, Laboratory Directed Research and Development Funding, under Contract No. DE-AC05-06OR23177 JLEIC is the medium energy electron-ion collider currently under active design at Jefferson Lab*. The design goals of JLEIC are both high luminosity (1033-1034 cm-2ses−1) and high polarization (>70%) for the electron and light ion beams, for a wide range of electron and ion beam energies and for a wide spectrum of ion species. The unprecedented luminosity goal for this electron-ion collider sets strong requirements for the understanding and management of potential collective effects in JLEIC. In this paper, we present preliminary estimations of single and coupled bunch coherent instabilities for the electron and proton beams at collision energies for the JLEIC design. Further improvement of the estimations and mitigation methods are discussed. * MEIC design summary, http://arxiv.org/ftp/arxiv/papers/1504/1504.07961.pdf, (2015).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB080
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THPAB081	The Effects of Space-Charge on the Dynamics of the Ion Booster in the Jefferson Lab EIC (JLEIC)	3906
	E.W. Nissen, S.A. Bogacz JLab, Newport News, Virginia, USA
	Funding: Notice: This manuscript has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy. Optimization of the booster synchrotron design to operate in the extreme space-charge dominated regime is proposed. This study is motivated by the ultra-high luminosity promised by the JLEIC accelerator complex, which poses several beam dynamics and lattice design challenges for its individual components. We examine the effects of space charge on the dynamics of the booster synchrotron for the proposed JLEIC electron ion collider. This booster will inject and accumulate protons and heavy ions at an energy of 280 MeV and then engage in a process of acceleration and electron cooling to bring it to its extraction energy of 8 GeV. This would then be sent into the ion collider ring part of JLEIC. In order to examine the effects of space charge on the dynamics of this process we use the software SYNERGIA.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB081
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THPAB082	The Beam-Beam Effect and Its Consequences for the Modeling of the Jefferson Lab EIC	3909
	E.W. Nissen JLab, Newport News, Virginia, USA
	Funding: Notice: This manuscript has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy In this work we address the effect of beam jitter on emittance growth as caused by the beam-beam effect on the Jefferson Lab Electron Ion Collider (JLEIC). This proposed collider would collide up to 100 GeV proton beams with up to 10 GeV electron beams. Due to the asymmetric rigidities of the beams and their non-linear lensing action on each other during a collision, collective effects can limit beam storage times. Using simulations we determined that one of JLEIC's synchronization concepts would require a new set of software tools to accurately understand phase space evolution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB082
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THPAB084	Integration of the Full-Acceptance Detector Into the JLEIC	3912
	G.H. Wei, F. Lin, V.S. Morozov, F.C. Pilat, Y. Zhang JLab, Newport News, Virginia, USA Y.M. Nosochkov SLAC, Menlo Park, California, USA M.-H. Wang Self Employment, Private address, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported also by the U.S. DOE Contract DE-AC02-76SF00515. For physics requirements, the JLEIC (Jefferson Lab Electron Ion Collider) has a full-acceptance detector, which brings many new challenges to the beam dynamics integration. For example, asymmetric lattice and beam envelopes at interaction region (IR), forward detection, and large crossing angle with crab dynamics. Also some common problems complicate the picture, like coupling and coherent orbit from detector solenoid, high chromaticity and high multipole sensitivity from low beta-star at interaction point (IP), collision mode with different energy and ion species. Meanwhile, to get a luminosity level of a few 1033 cm-2ses−1, small beta-star are necessary at the IP, which also means large beta in the final focus area, chromaticity correction sections, etc. This sets a constraint on the field quality of magnets in large beta areas, in order to ensure a large enough dynamic aperture (DA). In this context, limiting multipole components of magnets are surveyed to get a standard line. And continuously, multipole magnets as dedicated correctors are studied to provide semi-local corrections of specific multipole components beyond the standard line.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB084
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THPAB085	Simulations of Coherent Synchrotron Radiation on Parallel Hybrid GPU/CPU Platform	3915
	B. Terzić, D. Duffin, A.L. Godunov ODU, Norfolk, Virginia, USA A. Arumugam, T. Islam, D. Ranjan, S. Sangam, M. Zubair ODU CS, Norfolk, Virginia, USA
	Funding: National Science Foundation 1535641 Coherent synchrotron radiation (CSR) is an effect of self-interaction of an electron bunch as it traverses a curved path. It can cause a significant emittance degradation, as well as fragmentation and microbunching. Numerical simulations of the 2D/3D CSR effects have been extremely challenging due to computational bottlenecks associated with calculating retarded potentials via integrating over the history of the bunch. We present a new high-performance 2D, particle-in-cell code which uses massively parallel multicore GPU/GPU platforms to alleviate computational bottlenecks. The code formulates the CSR problem from first principles by using the retarded scalar and vector potentials to compute the self-interaction fields. The speedup due to the parallel implementation on GPU/CPU platforms exceeds three oders of magnitude, thereby bringing a previously intractable problem within reach. The accuracy of the code is verified against analytic 1D solutions (rigid bunch) and semi-analytic 2D solutions for the chirped bunch. Finally, we use the new code in conjunction with a genetic algorithm to optimize the design of a fiducial chicane.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB085
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THPAB086	Long-Term Simulations of Beam-Beam Dynamics on GPUs	3918
	B. Terzić, C.M. Cotnoir, A.L. Godunov, T. Satogata, M. Stefani ODU, Norfolk, Virginia, USA A. Arumugam, R.T. Majeti, D. Ranjan, M. Zubair ODU CS, Norfolk, Virginia, USA F. Lin, V.S. Morozov, E.W. Nissen, Y. Roblin, T. Satogata, H. Zhang JLab, Newport News, Virginia, USA
	Funding: Jefferson Lab Future machines such as the electron-ion colliders (JLEIC), linac-ring machines (eRHIC) or LHeC are particularly sensitive to beam-beam effects. This is the limiting factor for long-term stability and high luminosity reach. The complexity of the non-linear dynamics makes it challenging to perform such simulations which require millions of turns. Until recently, most of the methods used linear approximations and/or tracking for a limited number of turns. We have developed a framework which exploits a massively parallel Graphical Processing Units (GPU) architecture to allow for tracking millions of turns in a sympletic way up to an arbitrary order and colliding them at each turn. The code is called GHOST for GPU-accelerated High-Order Symplectic Tracking. As of now, there is no other code in existence that can accurately model the single-particle non-linear dynamics and the beam-beam effect at the same time for a large enough number of turns required to verify the long-term stability of a collider. Our approach relies on a matrix-based arbitrary-order symplectic particle tracking for beam transport and the Bassetti-Erskine approximation for the beam-beam interaction.
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THPAB087	Emittance Measurements and Simulations in 112 MHz Super-Conducting RF Electron Gun With CsK2Sb Photo-Cathode	3921
SUSPSIK063	use link to see paper's listing under its alternate paper code
	K. Mihara Stony Brook University, Stony Brook, USA D. Kayran, V. Litvinenko, T.A. Miller, I. Pinayev BNL, Upton, Long Island, New York, USA
	The commissioning of the coherent electron cooling (CeC) proof of principle experiment is under way at Relativistic Heavy Ion Collider (RHIC).. A 112 MHz superconducting radio frequency photo-emission gun is used to generate the electron beam for this experiment. In this paper we report selected results of experimental emittance measurements and compare them with our simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB087
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THPAB088	Comparison of Theory, Simulation, and Experiment for Dynamical Extinction of Relativistic Electron Beams Diffracted Through a Si Crystal Membrane	3924
SUSPSIK064	use link to see paper's listing under its alternate paper code
	L.E. Malin, W.S. Graves, J. Spence, C. Zhang Arizona State University, Tempe, USA R.K. Li, C. Limborg, E.A. Nanni, X. Shen, S.P. Weathersby SLAC, Menlo Park, California, USA
	Diffraction in the transmission geometry through a single-crystal silicon slab is exploited to control the intensity of a relativistic electron beam. The choice of crystal thickness and incidence angle can extinguish or maximize the transmitted beam intensity via coherent multiple Bragg scattering; thus, the crystal acts as a dynamical beam stop through the Pendel'sung effect, a well-known phenomenon in X-ray and electron diffraction. In an initial experiment, we have measured the ability of this method to transmit or extinguish the primary beam and diffract into a single Bragg peak. Using lithographic etching of patterns in the crystal we intend to use this method to nanopattern an electron beam for production of coherent x-rays. We compare the experimental results with simulations using the multislice method to model the diffraction pattern from a perfect silicon crystal of uniform thickness, considering multiple scattering, crystallographic orientation, temperature effects, and partial coherence from the momentum spread of the beam. The simulations are compared to data collected at the ASTA UED facility at SLAC for a 340 nm thick Si(100) wafer with a beam energy of 2.35 MeV.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB088
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THPAB090	Algorithm to Calculate Off-Plane Magnetic Field From an on-Plane Field Map	3928
	N. Tsoupas, J.S. Berg, F. Méot, V. Ptitsyn, D. Trbojevic BNL, Upton, Long Island, New York, USA S.A. Kahn Muons, Inc, Illinois, USA S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We present an algorithm to calculate the off-plane components of the magnetic field from the on-plane components of the magnetic field which are measured on a grid of the plane. The algorithm, which is a general one and it is not restricted on a mid-plane symmetry, is based on the Taylor series expansion of the magnetic field components in terms of the normal to the plane location. The coefficients of the Taylor series expansion are expressed in terms of the on-plane derivatives of the field components which are generated by the measured magnetic field components on the grid of the plane. The algorithm is use in the RATRACE computer code[*] and has been used[**] on a dipole magnet with median plane symmetry. * S.B. Kowalski and H.A. Enge The Ion-Optical Program Raytrace NIM A258 (1987) 407 ** N. Tsoupas et. al. Effects of Dipole Magnet Inhomogeneity on the Beam Ellipsoid NIM A258 (1987) 421-425
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB090
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THPAB092	Orbit and Dispersion Tool at European XFEL Injector	3932
SUSPSIK088	use link to see paper's listing under its alternate paper code
	N. Ghazaryan CANDLE SRI, Yerevan, Armenia M.E. Castro Carballo, W. Decking DESY, Hamburg, Germany
	Trajectory and electron beam size play an essential role in Free Electron Laser (FEL) obtainment. Since transverse dispersion changes off-energy particle trajectories and increases the effective beam size, dispersion and orbit must constantly be controlled and corrected along the whole lattice. In this paper the principles underlying the orbit and dispersion correction tool, developed at DESY, are described. The results of its testing on European XFEL injector are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB092
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THPAB093	Synchronization of a Photo-Injector and a High Power Laser With Independent Clocks	3935
	N. Delerue, C. Bruni, K. Cassou, V. Chaumat, R. Chiche, D. Douillet, N. ElKamchi, S. Jenzer, V. Kubytskyi, P. Lepercq, H. Purwar, H. Roesch LAL, Orsay, France E. Baynard, M. Pittman CLUPS, Orsay, France J. Demailly, O. Guilbaud, S. Kazamias, G. Maynard, O. Neveu, D. Ros CNRS LPGP Univ Paris Sud, Orsay, France D. Garzella CEA, Gif-sur-Yvette, France R. Prazeres LCP/CLIO, Orsay, Cedex, France
	Funding: LAL/IN2P3/CNRS and Université Paris-Sud The plasma acceleration project ESCULAP (ElectronS CoUrts pour L'Acc\'el\'eration Plasma) aims at studying electrons injection into a laser plasma accelerator. This requires the injection of short electron bunches generated by the photo injector PHIL (Photo injector at LAL) into a plasma wave by the high power femtosecond Laser LASERIX. As a first step we have studied how to synchronize PHIL and LASERIX. As these two machines had not been initially designed to work together, simple synchronization solutions were not available. We detail here the synchronisation scheme that we have tested and the experimental results obtained.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB093
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THPAB095	Detuning Compensation in SC Cavities Using Kalman Filters	3938
	A. Ushakov, P. Echevarria, A. Neumann HZB, Berlin, Germany
	For CW driven superconducting cavities operating at small bandwidth, like in ERL or FEL light sources, it is mandatory to precisely control any source of detuning. Therefore, a Kalman [1] filter based approach was developed and implemented as FPGA firmware to act as the core part of a detuning compensation algorithm. It relies on a fit by a second order model to a measured transfer function of cavity's forced oscillations with damping, caused by piezo drives and data about observed current phase with some adjustable confidence rate. The initial data for this core is taken from field detection firmware on mTCA.4's SIS8300-L2 digitizer, transferred by low latency links to a carrier board equipped by piezo drive controller where the DSP processing by the Kalman algorithm performed. The processing is characterized by a 550 kHz rate in pipeline mode and occupies almost all DSP resources of the Spartan 6 FPGA chip. The experimental results of detuning compensating technique applied to a SC photoinjector cavity are presented in this contribution. Kalman, R. E. (1960): A New Approach to Linear Filtering and Prediction Problems, Transaction of the ASME, Journal of Basic Engineering, Pages 35-45.
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THPAB096	Automatized Optimization of Beam Lines Using Evolutionary Algorithms	3941
	S. Appel, V. Chetvertkova, W. Geithner, F. Herfurth, U. Krause, S. Reimannpresenter, M. Sapinski, P. Schütt GSI, Darmstadt, Germany D. Österle KIT, Karlsruhe, Germany
	Due to the massive parallel operation modes at GSI accelerators, a lot of accelerator setup and re-adjustment has to be made by operators during a beam time. This is typically done manually using potentiometers and is very time-consuming. With the FAIR project the complexity of the accelerator facility increases further and for efficiency reasons it is recommended to establish a high level of automation for future operation. Modern Accelerator Control Systems allow a fast access to both, accelerator settings and beam diagnostics data. This provides the opportunity to implement algorithms for automated adjustment of e.g. magnet settings to maximize transmission and optimize required beam parameters. The fast-switching magnets in GSI-beamlines are an optimal basis for an automatic exploration of the parameter-space. The optimization of the parameters for the SIS18 multi-turn-injection using a genetic algorithm has already been simulated*. The first results of our automatized online parameter optimization at the CRYRING@ESR injector are presented here. [*] S. Appel, O. Boine-Frankenheim: Optimization of Multi-turn Injection into a Heavy-Ion Synchrotron using Genetic Algorithms, Proceedings of IPAC2015, Richmond, USA (2015)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB096
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THPAB097	Phase Calibration of Synchrotron RF Signals	3945
	A. Andreev, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany H. Klingbeil, D.E.M. Lens GSI, Darmstadt, Germany
	In the scope of FAIR's scientific program higher beam intensities will be achieved and several new synchrotrons (including storage rings) are being built. The low-level RF (LLRF) systems of FAIR have to support multi-harmonic operations, barrier bucket generation and bunch compression in order to meet the desired beam quality requirements. All this imposes several requirements on the LLRF systems. For example the phase error of the gap voltage of a specific RF cavity must be less than 3 degrees. Thus, each individual component must have a better accuracy. The RF reference signals for the FAIR synchrotron RF cavity systems are generated by direct digital synthesis (DDS). Four so-called Group DDS modules are mounted in one crate. In the supply rooms, the reference signals of such a crate are then distributed to local cavity LLRF systems. Therefore, the precise phase calibration of Group DDS modules is of importance. A phase calibration method with respect to the absolute phases of DDS modules defined by means of the FAIR Bunch Phase Timing System (BuTiS) is developed, and its precision is under evaluation.
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THPAB098	Test Setup for Automated Barrier Bucket Signal Generation	3948
	K. Groß, D. Domont-Yankulova, J. Harzheim, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany M. Frey, H. Klingbeil GSI, Darmstadt, Germany
	Funding: Work supported by the German Federal Ministry of Education and Research (BMBF) under the project 05P15RDRBA. For sophisticated beam manipulation several ring accelerators at FAIR and GSI like the main synchrotron SIS100 and the ESR will be equipped with barrier bucket systems. Hence, the associated LLRF has to be applicable to different RF systems, with respect to the cavity layout and the power amplifier used, as well as to variable repetition rates and amplitudes. Since already the first barrier bucket pulse of a long sequence has to meet certain minimum demands, an open-loop control on the basis of calibration data is foreseen. Closed-loop control is required to improve the signal quality during a sequence of pulses and to adapt to changing conditions like temperature drifts. A test setup was realized that allows controlling the signal generator, reading out the oscilloscope as well as processing the collected data. Frequency and time domain methods can be implemented to approach the dynamics of the RF system successively and under operating conditions, i.e. generating single sine pulses. The setup and first results from measurements are presented as a step towards automated acquisition of calibration data and iterative improvement of the same.
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THPAB099	Challenges of a Stable ERL Operation Concerning the Digital RF Control System of the S-DALINAC	3951
	M. Steinhorst, M. Arnold, U. Bonnes, C. Burandt, N. Pietralla TU Darmstadt, Darmstadt, Germany T. Kürzeder HIM, Mainz, Germany
	Funding: Supported by the DFG through RTG 2128. The superconducting recirculating electron linear accelerator S-DALINAC is the central large-scale research device of the institute for nuclear physics at the TU Darmstadt in Germany. In 2015/2016 the S-DALINAC received an upgrade to three recirculations. The new beam line enables in addition to higher maximum energies the possibility to operate the S-DALINAC as an Energy Recovery Linac (ERL). Therefore the current rf control system encounters new requirements for ERL operation. Since 2010 a digital rf control system is successfully used for the control of the superconducting cavities. This system was not built and optimized for the control of an ERL. This contribution is discussing the expected challenges of an ERL operation regarding the existing digital rf control system.
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THPAB100	On the Impact of Empty Buckets on the Ferrite Cavity Control Loop Dynamics in High Intensity Hadron Synchrotrons	3954
	D. Mihailescu Stoica, D. Domont-Yankulova Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany D. Domont-Yankulova, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany H. Klingbeil, D.E.M. Lens GSI, Darmstadt, Germany
	Funding: Supported by the Helmholtz Graduate School for Hadron and Ion Research Due to technical reasons two of ten buckets have to stay empty in the planned SIS100 synchrotron at the GSI Helmholtzzentrum für Schwerionenforschung. The planned low level RF control systems consist of linear P and PI type controllers. These are responsible to maintain a desired phase and amplitude of the gap voltage. In addition the cavity is controlled to follow a prescribed resonance frequency ramp. In SIS100 the acceleration will be performed by ferrite cavities with comparatively small quality factors. Therefore, effects resulting from transient beam loading have to be expected. Influences due to empty buckets are analysed in the frequency domain and particle tracking simulations are carried out to estimate the effect on the overall system with particular consideration of emittance growth and particle loss.
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THPAB103	On-Line RF Amplitude and Phase Calibration	3957
	M.K. Grecki, V. Ayvazyan, J. Branlard, M. Hoffmann, M. Omet, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany
	The accelerating RF field has crucial importance on the beam properties. It is not only used just to accelerate particles but also to shape the bunches at bunch compressors. It is really important to control and measure the field as seen by the beam while usually only indirect (not using the beam) field measurements are available*. Since they are affected by many contributions the measurements must be always calibrated to the beam. Usually this calibration is performed at special operating conditions that prevents normal operation of the accelerator. During normal operation the calibrations is assumed to not drift which is certainly not perfectly true and introduce some control errors. The paper shows how to extract the RF-beam calibration from RF signals during normal operating condition (when RF feed-back, beam loading compensation, learning feed-forward etc. are active). All the algorithms and computations were performed on signals recorded at FLASH accelerator but the main idea is general and can be used at other locations as well.
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THPAB104	Engineering Documentation and Asset Management for the European XFEL Accelerator	3960
	L. Hagge, J.A. Dammann, T.T. Hongisto, J. Kreutzkamppresenter, D. Käfer, B. List, S. Rohwedder, S. Sühl, N. Welle DESY, Hamburg, Germany A. Frank European XFEL, Schenefeld, Germany
	At the European XFEL, extensive technical documentation has been created during design and construction of the accelerator. It is based on a configuration database (the DESY EDMS), which provides an inventory of major accelerator systems. The configuration database registers components and their used materials, tracks component design and fabrication history, and contains engineering documents and drawings, and work and inspection records. Technical documentation can be accessed through intuitive reports and navigational tree structures, representing specific beamline sections or areas of the facility. Access on mobile devices in the accelerator tunnel is supported by component tags with QR codes. A dedicated front-end has been developed for automatically uploading and cross-linking documents to the configuration database, reducing documentation efforts in the project teams. The configuration database now serves as a foundation for upcoming technical operation and maintenance activities. The paper provides an overview of the available engineering documentation and its access methods, and discusses its expected role and benefits in future maintenance processes.
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THPAB105	Design and Operation of the Integrated 1.3 GHz Optical Reference Module with Femtosecond Precision	3963
	T. Lamb, Ł. Butkowski, E.P. Felber, M. Felber, M. Fenner, S. Jabłoński, T. Kozak, J.M. Müller, P. Prędki, H. Schlarb, C. Sydlo, M. Titberidze, F. Zummack DESY, Hamburg, Germany
	In modern Free-Electron Lasers like FLASH or the European XFEL, the short and long-term stability of RF reference signals gains in importance. The requirements are driven by the demand for short FEL pulses and low-jitter FEL operation. In previous publications, a novel, integrated Mach-Zehnder Interferometer based scheme for a phase detector between the optical and the electrical domain was presented and evaluated. This Laser-to-RF phase detector is the key component of the integrated 1.3 GHz Optical Reference Module (REFM-OPT) for FLASH and the European XFEL. The REFM-OPT will phase-stabilize 1.3 GHz RF reference signals to the pulsed optical synchronization systems in these accelerators. Design choices in the final hardware configuration are presented together with measurement results and a performance evaluation from the first operation period in the European XFEL.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB105
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THPAB106	Experience with Single Cavity and Piezo Controls for Short, Long Pulse and CW Operation	3966
	K.P. Przygoda, V. Ayvazyan, R. Rybaniec, H. Schlarb, Ch. Schmidt, J.K. Sekutowicz DESY, Hamburg, Germany P. Echevarria HZB, Berlin, Germany
	We present a compact RF control system for SCRF single cavities based on MicroTCA.4 equipped with specialized advanced mezzanine cards (AMCs) and rear transition modules (RTMs). To sense the RF signals from the cavity and to drive the high power source, a DRTM-DWC8VM1 module is used equipped with 8 analog field detectors and one RF vector modulator. Fast cavity frequency tuning is achieved by piezo-actuators attached to the cavity and a RTM piezo-driver module (DRTM-PZT4). Data processing of the RF signals and the real-time control algorithms are implemented on a Virtex-6 FPGA and a Spartan FPGAs within two AMCs (SIS8300-L2V2 and DAMC-FMC20). The compact single cavity control system was tested at Cryo Module Test Bench (CMTB) at DESY. Software and firmware were developed to support all possible modes, the short pulse (SP), the long pulse (LP) and CW operation mode with duty cycles ranging from 1 % to 100%. The SP mode used a high power multi-beam klystron at low QL ~3·106. For the LP mode (up to 50% duty cycle) and the CW mode a 120 kW IOT tube was used at QL up to 1.5·107. Within this paper we present the achieved performance and report on the operation experience on such system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB106
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THPAB108	Femtosecond Optical Synchronization System for the European XFEL	3969
	C. Sydlo, M. Felber, C. Gerth, T. Kozak, T. Lamb, J.M. Müller, H. Schlarb, F. Zummack DESY, Hamburg, Germany
	Accurate timing synchronization on the femtosecond timescale is an essential installation for time-resolved experiments at free-electron lasers (FELs) such as FLASH and the upcoming European XFEL. Conventional RF timing systems suffer from RF attenuation for such long distances and have reached to date a limit for synchronization precision of around 100 femtoseconds. An optical synchronization system is used at FLASH and is based on the distribution of femtosecond laser pulses over actively stabilized optical fibers. The upcoming European XFEL has raised the demands due to its large number of stabilized optical fibers and a length of 3400 m. The increased lengths for the stabilized optical fibers necessitated major advancement in precision to achieve the requirement of less than 10 femtosecond precision. This paper reports on the status of the laser-based synchronization system at the European XFEL.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB108
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THPAB109	Fs Level Laser-to-RF Synchronization at REGAE	3972
	M. Titberidze, M. Felber, T. Lamb, H. Schlarb, C. Sydlo DESY, Hamburg, Germany R.A. Loch MPSD, Hamburg, Germany
	The Relativistic Electron Gun for Atomic Exploration (REGAE) is a unique linear accelerator capable of producing ultrashort (~ 10 fs) electron bunches for studying fast processes in matter by means of ultrafast electron diffraction (UED) experiments. Additionally, REGAE is suitable for upcoming external injection experiments for laser wakefield acceleration (LWFA). In order to carry out both mentioned experiments, it is crucial to achieve fs level stability in terms of Laser-to-RF synchronization. In this paper we present an advanced laser-to-RF synchronization scheme based on integrated Mach-Zehnder modulator. The setup demonstrated the Titanium Sapphire photo-injector laser synchronization with 11 fs (rms) precision in the bandwidth up to 100 kHz. Long term timing drift measurements showed unprecedented peak-to-peak stability of 31 fs (7 fs rms) over 43 hours of measurement time. In addition, AM-PM coefficient of the MZM based laser-to-RF synchronization setup has been evaluated and showed a factor of 10 improved performance compared to conventional direct conversion based laser synchronization setup.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB109
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THPAB110	Custom Optomechanics for the Optical Synchronization System at the European XFEL	3976
	F. Zummack, M. Felber, C. Gerth, T. Lamb, J.M. Müller, M. Schäfer, H. Schlarb, C. Sydlo DESY, Hamburg, Germany
	Free-electron-lasers like the upcoming European XFEL demand highly reliable optical synchronization in range of few femtoseconds. The well known optical synchronization system at FLASH had to be re-engineered to meet XFEL requirements comprising demands like ten times larger lengths and raised numbers of optically synchronized instruments. These requirements directly convert to optomechanical precision and have yielded in a specialized design accounting for economical manufacturing technologies. These efforts resulted in reduced spatial dimensions, improved optical repeatability, maintainability and even reduced production costs. To account for thermal influences the heart of the optical synchronization system is based on an optical table made out of SuperInvar. To fully exploit its excellent thermal expansion coefficient, mechanical details need to be taken into account. This work presents the design and its realization of the re-engineered optomechanical parts of the optical synchronization system, comprising mounting techniques, link stabilization units and optical delay lines for high drift suppression.
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THPAB111	Sub-Femtosecond Jitter Ultra High Performance Oscillators for Accelerator Timing	3979
	A. Gronefeld Ingenieurbüro Gronefeld, Herten, Germany
	Extremely stable RF-Sources are at the heart of Electron Beam Accelerators and impact beam quality and beam energy. Jitter requirements on those sources are very tight and linked to the quest of ever decreasing (XFEL) laser pulse length, currently in the tens of femtoseconds. For the Pohang Accelerator Laboratory in Pohang/Korea, a 2.856GHz phase-lockable oscillator with a jitter performance of 0.8fS (10kHz..10MHz) was developed and deployed, together with a master oscillator that supplies rubidium-stabilized 476MHz for synchronization. In terms of phase noise, these 2.856GHz oscillators exhibit -125dBc/Hz@1kHz, -145dBc/Hz@10kHz and -165dBc/Hz@100kHz offset, while reaching a noise floor of -180dBc/Hz. Using the same technology of a dielectric resonator oscillator, a 3.9GHz source was developed for the European XFEL at DESY/Hamburg, achieving 0.3fS (10kHz/10MHz). Phase noise is down to -125dBc/Hz@1kHz, -155dBc/Hz@10kHz and -175dBc/Hz@100kHz offset, with a noise floor of -180dBc/Hz. The strategy of designing ultra low phase-noise sources with dielectric resonators is outlined, and challenges and limitations within the oscillator design, but also measurement technology are presented.
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THPAB113	Time Synchronization for Distant IOCs of the SuperKEKB Accelerators	3982
	H. Kaji, T. Naito, S. Sasaki KEK, Ibaraki, Japan Y. Iitsuka EJIT, Hitachi, Ibaraki, Japan
	The time synchronization for multi CPU system is always a problem to be worried. The control system of accelerator is no exception since it consists of a lot of CPUs located among large area distantly. The problem appears conspicuously when the beam is aborted. Usually, several hardware show abort signals in one beam abort event. However it is difficult to know which is the source of beam abort and which issues an abort signal under the influence of original failure. We introduce the time synchronization system of the SuperKEKB collider which choose EPICS as the control software. The system utilize Event Timing System and synchronizes the EPICS general time for I/O controllers located distantly. The accuracy of synchronization is around 10ns. It is the excellent performance in terms of synchronization of CPU time. The all abort channels of SuperKEKB are synchronized their issued time. Besides they synchronize with also the injector linac which is operated with the different control system in different network.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB113
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THPAB114	Operation of LLRF Control Systems in SuperKEKB Phase-1 Commissioning	3986
	T. Kobayashi, K. Akai, K. Ebihara, A. Kabe, K. Nakanishi, M. Nishiwakipresenter, J.-I. Odagiri, S.I. Yoshimoto KEK, Ibaraki, Japan K. Hirosawa Sokendai, Ibaraki, Japan
	First beam commissioning of SuperKEKB (Phase-1), which had started in February 2016 and continued until the end of June, has been successfully accomplished. Target beam current for Phase-1 needed for sufficient vacuum scrubbing was achieved in both 7-GeV electron and 4-GeV positron rings. This presentation summarize the operation results related to low level RF (LLRF) control issues during the Phase-1 commissioning, including the system tuning, the coupled bunch instability and the bunch gap transient effect. RF system of SuperKEKB consists of about thirty klystron stations in both rings. Newly developed LLRF control system, which is composed of recent digital technique, is applied to the nine stations among the thirty for Phase-1. The RF reference signal distribution system has been also upgraded for SuperKEKB. These new systems worked well without serious problem and they contributed to smooth progress of the commissioning. The old existing systems, which had been used in the KEKB operation, were still reused for the most stations, and they also worked as soundly as performed in the KEKB operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB114
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THPAB115	Development of a Longitudinal Feedback System for Coupled Bunch Instabilities Caused by the Accelerating Mode at Superkekb	3989
	K. Hirosawa, K. Akai, E. Ezura, T. Kobayashi, K. Nakanishi, M. Nishiwakipresenter, S.I. Yoshimoto KEK, Ibaraki, Japan
	SuperKEKB is an asymmetric energy electron-positron circular collider. Phase-I commissioning was operated from February to June in 2016. The purpose of this accelerator is to aim at the higher luminosity than KEKB, so a larger beam current is made for it. In the future plan, beam currents in the electron and positron rings will be increased to 2.6A and 3.6A, respectively. As we consider beam dynamics in the storage ring, higher mode instability associated with the accelerating mode will be caused by a large beam current. Especially the target instability of this study is called μ=-2 mode Coupled Bunch Instability. To suppress it, we developed new feedback components for longitudinal coupled bunch instability. We have same mechanism feedback components for KEKB, but it supports only μ=-1 mode instability. Since a large current makes μ=-1 mode instability big, there is a possibility that suppression is difficult only by using KEKB components. In order to deal with this problem, new components we developed support μ=-1, -2, and -3 mode instabilities, and we improved the performance and usability as compared to existing components. We schedule studies using a beam at Phase-II.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB115
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THPAB116	Evaluation of Digital LLRF Control System Performance at STF in KEK	3992
SUSPSIK087	use link to see paper's listing under its alternate paper code
	S.B. Wibowo, N. Liu Sokendai, Ibaraki, Japan T. Matsumoto, S. Michizono, T. Miura, F. Qiu KEK, Ibaraki, Japan
	The Superconducting RF Test Facility (STF) at the High Energy Accelerator Research Organization (KEK) was built for research and development of the International Linear Collider (ILC). Several digital low-level radio frequency (LLRF) control systems were developed at the STF. The purposes of these developments are to construct a minimal configuration of the ILC LLRF system and achieve the amplitude and phase stability of the accelerating field in the superconducting accelerator. Evaluations of digital LLRF control systems were conducted during the conditioning of eight superconducting cavities performed between October and November 2016. The digital LLRF control system configured for ILC was demonstrated and the performance fulfilled the required stability criteria of the accelerating field in the ILC. These evaluations are reported in this paper.
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THPAB117	Development of a New LLRF System Based on MicroTCA.4 for the SPring-8 Storage Ring	3996
	T. Ohshima, H. Ego, N. Hosoda, H. Maesaka RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan T. Fukui RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan M. Ishii JASRI/SPring-8, Hyogo-ken, Japan
	SPring-8 is a 3rd generation synchrotron radiation facility, which has been operated since 1997. The analog-circuit-based rf modules now in use at the storage ring are obsolete and hard to be maintained. The renewal of them with modern digital ones is underway and the developed LLRF system will be used for the operation of SPring-8-II. We built an amplitude and phase stabilizing system with commercial MicroTCA.4 modules. A motor driver controlled through EtherCAT was newly adapted to the cavity tuner. The system was implemented to the high power rf test stand which consists of a 1 MW klystron, a circulator, and a 508.58 MHz cavity. The rf power was successfully regulated to keep the cavity voltage with an amplitude deviation of less than 0.1% and a phase stability of less than 0.1 degree in rms. We are also developing new MTCA.4 modules: a digitizer AMC having sampling rate of 370 MHz and 16bit resolution, and a signal conditioning RTM. These modules are used for under-sampling rf detection achieving simple composition and more robustness to the ambient parameter changes. We will start installation of the digital system to one of four rf stations in the storage ring in summer 2017.
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THPAB118	Stabilization of Timing System Operation of J-PARC Linac and RCS	4000
	H. Takahashi, N. Hayashipresenter JAEA/J-PARC, Tokai-mura, Japan Y.I. Itoh Total Support Systems Corporation, Tokai-mura, Naka-gun, Ibaraki, Japan M. Kawase, Y. Sawabe Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
	At the timing system for J-PARC Linac and Rapid Cycling Synchrotron (RCS), the distribution of timing information (beam tag, type, etc.) and the monitoring and control of timing system are performed via the reflective memory (RFM). The more 10 years elapsed after operation start of J-PARC. Therefore, it is concerned about the occurrence of malfunctions due to time-related deterioration of the devices of timing system. Especially, the malfunctions of a management computer to monitor and control the all timing devices and RFMs to configure the timing system data network have a significant impact. Then, the management computer was renewed and PCI-Express RFMs are installed instead of PCI RFMs. However, after renewal computer, the trouble by data corruption of RFM network was happened anew. In this paper, the contents and the results our cause investigation of data corruption and those of the measures employed for stabilizing the timing system operation are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB118
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THPAB119	Study on a Time-Domain Spectroscopy System for Coherent Terahertz Pulse Spectrum Measurement from 5 MeV Electron Beam	4003
	R. Yanagisawa, T. Toida Waseda University, Tokyo, Japan K. Kan ISIR, Osaka, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan M. Washio RISE, Tokyo, Japan
	Funding: This work was supported by a research granted from The Murata Science Foundation and JSPS KAKENHI 26286083. Terahertz wave, expected to apply spectral analysis and imaging, has recently developed both source and detector components. For the terahertz source, the coherent radiation from electron linac is expected to be the high power terahertz source. At Waseda University, we have been studying high quality electron beam generation using Cs-Te photocathode RF-Gun and its application. We tried to generate terahertz wave by the coherent radiation and to measure its spectrum by a time-domain spectroscopy (TDS) technique. Adopting this technique, ultra-short laser pulse is needed as probe light. A terahertz waveform appears by delaying the timing of probe pulse. A spectrum of terahertz wave is also led by the waveform, by using the Fourier transform. We succeeded in constructing the probe laser system operating at 119 MHz repetition rate. The pulse duration was compressed down to 190 fs (FWHM) by using pulse compressor. We also succeeded in measuring a terahertz radiation from a photoconductive antenna. In this conference, we will report the outline of our terahertz TDS system, recent progress of our laser system, and terahertz wave generation and detection, with the future prospects.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB119
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THPAB121	The Study of Accelerator Data Archiving and Retrieving Software	4007
SUSPSIK089	use link to see paper's listing under its alternate paper code
	Y.S. Qiao, G. Lei, Z. Zhao IHEP, Beijing, People's Republic of China
	This paper presents a novel archiving and retrieving software designed for BEPC-II and other particle accelerators. At BEPC-II, real-time data are stored as index files recorded by traditional EPICS Channel Archiver. Never-theless, index files are not suitable for long-term maintenance and difficult for data analysis. The NoSQL database MongoDB is used for this new system due to aging technologies, so as to promote the data storage reliability, usability, and possible future advanced data analysis. A cross-platform UI (User Interface) has also been developed to make it quicker and easier to access the database. The writing and query performance are tested for this software.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB121
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THPAB122	Open XAL Development for Xi'an Proton Application Facility	4010
	Y. Yang, X. Guan, Y. Leipresenter, W. Wang, X.W. Wang, S.X. Zheng TUB, Beijing, People's Republic of China M.C. Wang, Z.M. Wang, H.Z. Zhang State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Shannxi, People's Republic of China
	Beam commission tools for Xi'an Proton Application Facility (XiPAF) will be developed based on Open XAL. In this paper, we present preparations made for adopting Open XAL in XiPAF, including a newly designed database schema based on MySQL, modifying db2xal application based on database schema to create optics file automatically. We also add time-dependent nodes in XiPAF's online model to meet the need of energy ramping in synchrotron. A set of high-level applications as well as a new virtual accelerator is under development.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB122
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THPAB123	Low Level RF Control System Architecture OF IR-FEL	4014
	B. Du, G. Huang, L. Linpresenter, W. Liu, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Infrared free electron laser (IR-FEL) is one type of laser driven by accelerator and generated by undulator. It is built by National Synchrotron Radiation Laboratory (NSRL). Compared to synchrotron radiation light source, it have much higher demand of beam quality. Low level RF control system (LLRF) need to reach higher controlled accuracy corresponded to the demand. Accelerating structure which contains one pre-buncher, one buncher and two accelerating tube can accelerate beam to 60MeV. Frequency distribution system use direct digital synthesizer technology to generate 5 signal of different frequency. LLRF system detect 8 channels signal, one for control loop, and the others for monitor and interlock. The hardware contain MTCA.4 architecture which is advanced in global; RF board for downconverter and IQ modulation output; DSP board for sampling, controller and transmission.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB123
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THPAB124	DSP Frame and Algorithm of LLRF of IR-FEL	4017
	B. Du, G. Huang, L. Linpresenter, W. Liu, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Infrared Free Electron Laser (IR-FEL) use linear accelerator to accelerate electron to relative speed and then generate simulated radiation of infrared wavelength by periodic magnetic field of undulator. The amplitude and phase of microwave field need to be controlled precisely by low level RF control system (LLRF) to meet the high quality demand of electron from undulator. This paper mainly introduce the digital signal processing frame and feedback algorithm. Four times frequency sampling can realize IQ demodulation precisely and reduce DC offset, amplitude sampling error is less than 0.075% and phase sampling error is less than 0.1°. Pipeline CORDIC can calculate amplitude and phase by parallel processing and shift operation. Phase calculating accuracy reach 0.0005° when iteration count is 18. FIR filter is used to improve frequency selected performance. Feedback loop use digital PI controller to adjust system output.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB124
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THPAB127	Development of 1.3 GHz Cavity Combiner for 24 kW CW SSA	4020
SUSPSIK107	use link to see paper's listing under its alternate paper code
	W. Liu, B. Du, G. Huang, L. Lin, L. Shang, W.B. Song USTC/NSRL, Hefei, Anhui, People's Republic of China
	The 24KW CW SSA (Solid-State Amplifier) is being developed to drive the 1.3GHz SC Linac used in a THz light source. The SSA adopts the compact all-in-one combining method ' cavity combiner, which is proposed and developed in recent years. This paper reports the R&D of the cavity combiner. The cavity combiner resonates in TM010 mode, coupling with 24 coaxial-connected 1kW amplifier modules. The cavity's electromagnetic characteristic is calculated by CST, and the mechanical structure including the input and output coupler has been designed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB127
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THPAB128	Beam Arrival Time Analisis Based on CBPM at DCLS	4023
	S.S. Cao, J. Chen, L.W. Lai, Y.B. Leng SINAP, Shanghai, People's Republic of China N. Zhangpresenter SSRF, Shanghai, People's Republic of China
	Dalian Coherent Light Source is the first high gain free electron lasers (FEL) user facility in China, which is dedicated at extreme ultraviolet (EUV) spectral regime of 150-50nm for various scientific fields. In its undulator section, the beam-line was equipped with ten pair of high-precision cavity beam position monitor (CBPM), which can be used for beam position and beam arrival time (BAT) measurement. Based on this, we have done some preliminary research about the beam fight time with the reference cavities of CBPMs for the future research on BAT. In this paper, we presented the scheme of the beam fight time (BFT) research, analyzed the results, and evaluated the consistency and stability of BFT.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB128
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THPAB129	Contribution to the ESS LLRF System by Polish Electronic Group	4026
	J. Szewiński, M. Gosk, Z. Gołębiewski, P. Krawczyk, I.M. Kudla NCBJ, Świerk/Otwock, Poland A. Abramowicz, K. Czuba, M.G. Grzegrzolka, I. Rutkowski Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland W. Cichalewski, D.R. Makowski, A. Napieralski TUL-DMCS, Łódź, Poland
	Funding: Described work will be done as a part of polish in-kind contribution, granted by the Polish Ministry of Science and Higher Education in the decision number DIR/WK/2016/03. Development of the LLRF system at ESS is coordinated by the Lund University, but part of it, LLRF systems for M-Beta and H-Beta sections, will be delivered within in-kind contribution from Poland. This document will describe the scope of work, work plan, and technical details of the selected components of the M-Beta and H-Beta LLRF systems sections. Described contribution will be made by the Polish Electronic Group (PEG), a consortium of three scientific units. LLRF system for ESS will be made of both, commercially available components and components designed specially for this project, and those last ones will be presented and described here. Except the technical details, the organizational aspects, such as schedule, project management or quality control, will be presented as well.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB129
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THPAB131	Test of the Feedback and Feedforward Control Loop for Digital LLRF System of 1 MeV/n RFQ	4028
	H.S. Jeong, Y.-S. Cho, H.S. Kim, J.H. Kim, S.G. Kim, H.-J. Kwon, Y.G. Song Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
	Funding: This work has been supported through KOMAC (Korea of Multi-purpose Accelerator Complex) operation fund of KAERI by MSIP (Ministry of Science, ICT and Future Planning) KOMAC (Korea Multi-purpose Accelerator Complex) has a plan to develop the multipurpose ion irradiation system. This system includes the ion source, LEBT, RFQ and MEBT systems to transport ion particles to the target. In particular, the RFQ (Radio Frequency Quadrupole) system should receive 200 MHz RF within 1 % amplitude error stability. To supply stable 200 MHz RF signal to the RFQ cavity, the LLRF (Low-Level Radio Frequency) system should be controlled through a control system which implemented using commercial digital board. This 1 MeV/n RFQ LLRF system has a concept to minimize the number of the analog components for minimizing the control error. For this, the FPGA (Field Programmable Gate Array) in the digital board will control the frequency of the output sinusoidal signal. In addition, this LLRF system applied the direct sampling, Non-IQ sampling, direct RF generation and fast IQ set update rate algorithm. In this presentation, the LLRF PI control and feed-forward control logic test using 200 MHz dummy cavity will be described. LLRF, direct sampling, Non-IQ, RFQ, control loop, feedback, feedforward
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB131
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THPAB132	MCP Based Detectors Installation in European XFEL	4031
	E. Syresin, O.I. Brovko, A.Yu. Grebentsov JINR, Dubna, Moscow Region, Russia W. Freund XFEL. EU, Hamburg, Germany J. Grünert European XFEL, Schenefeld, Germany M.V. Yurkov DESY, Hamburg, Germany
	An important task of the photon beam diagnostics at the European XFEL is providing reliable tools for measurements aiming at the search for and fine tuning of the amplification process in the SASE FEL. Radiation detectors based onμchannel plates (MCP) were prepared for such measurements. These detectors operate in a wide dynamic range from the level of spontaneous emission to the saturation level (between a few nJ to 25 mJ), and in a wide wavelength range from 0.05 nm to 0.4 nm for SASE1 and SASE2, and from 0.4 nm to 5.1 nm for SASE3. Photon pulse energies are measured at the MCP anode and with a photodiode. The transverse photon beam profile is measured by an MCP imager with phosphor screen anode. Three MCP devices are being installed, one in each of the three FEL beamlines (SASE1, SASE2, and SASE3). The units for SASE1 and SASE3 were already installed in the XFEL tunnel, and the technical commissioning of the MCP detectors and their electronics is progressing. Calibration and acceptance test experiments with beam are scheduled for early 2017.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB132
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THPAB134	Latest Development of the ALBA DLLRF	4034
	A. Salom, B. Bravo, M. Broseta, E. Morales, J.R. Ocampo, F. Pérez, P. Solans ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	The Digital LLRF of ALBA has been implemented using commercial cPCI boards with Virtex-4 FPGA, fast ADCs and fast DACs. The firmware of the FPGA is based on IQ demodulation technique and the main feed-back loops adjust the phase and amplitude of the cavity voltage and also the resonance frequency of the cavity. This paper summarizes the latest LLRF developments done to improve performance of the RF systems and beam stability, including feed-forward loops based on phase modulation to compensate disturbances due to RF trip, beam loading compensation and Power Unbalance Compensation Loop for RF amplifiers Combination.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB134
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THPAB135	Digital LLRF for MAX IV	4037
	A. Salom, F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain Å. Andersson, R. Lindvall, L. Malmgren, A.M. Milan, A.M. Mitrovic MAX IV Laboratory, Lund University, Lund, Sweden
	The MAX IV facility consists of a 3 GeV Storage Ring(SR), a 1.5 GeV SR, and a linear accelerator (fed by two guns) that serves as a full-energy injector to the rings, but also as a driver for the Short Pulse Facility. The RF systems of the two SRs work at 100MHz. There are 6 normal conducting capacity loaded accelerating cavities and three Landau passive cavities in the 3GeV SR. In the 1.5GeV SR there are two accelerating cavities and two Landau cavities with the same characteristics. Each of these cavities is fed by a modular 60kW SSA. In the 3 GeV SR the power will be doubled by adding a second SSA when required. A digital Low Level RF system has been developed using commercial uTCA boards, with a Virtex-6 FPGA mother board (Perseus 601X) and two double stack FMC boards with fast ADCs and DACs. The large capabilities of state-of-the-art FPGAs allowed including the control of two normal conducing cavities and two landau cavities in one single LLRF system, reducing the development costs. Other utilities like the handling of fast interlocks and post-mortem analysis were also added to this system. This paper summarizes the main capabilities and performance of this DLLRF.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB135
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THPAB136	Kameleon - a Behavior-Rich, Non-Memoryless and Time-Aware Generic Simulator	4040
	R.N. Fernandes ESS, Lund, Sweden N. Senaud CEA/DRF/IRFU, Gif-sur-Yvette, France
	At ESS, thousands of devices will be used to control both the machine and end-station instruments. To enable ongoing development when access to these devices is not possible (for whatever the reason), Kameleon was implemented. It is a behavior-rich, non-memoryless and time-aware generic simulator that handles clients through a TCP/IP connection. An instance of this client is an EPICS IOC or a Tango Device Server. Kameleon consumes a user-defined file that describes the commands received from a client and, optionally, the reaction to these through statuses sent back to the client. Key features are: 1) Ubiquitous (runs in disparate platforms such as Windows and Linux). 2) Behavior-rich (predefined behaviors as well as user-defined). 3) Non-memoryless (the state of the simulation can be preserved between events and/or elapsed time). 4) Time-aware (statuses can be sent to the client either event-based or time-based). 5) Flexible (commands and statuses are described in a simple user-defined file - nothing is hard-coded in Kameleon). Kameleon will be used in a myriad of scenarios at ESS such as development of EPICS devices support, IOCs, OPI screens, testing of IOCs and alarm workflows.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB136
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THPAB137	New Approach in Developing Open XAL Applications	4043
	C. Rosati, E. Laface ESS, Lund, Sweden
	Open XAL project is a pure-Java open source development environment used for creating accelerator physics applications, scripts and services. Working with Open XAL requires developing a Java application with a prominent graphical user interface, allowing the final user to interact with the accelerator model, and to graphically view the results such interaction produced. Nevertheless the Open XAL support for specialized components (handling plotting, EPICS connection) and for a document-view application framework, relieving the developer of the burden related with this programming aspects, a lot of boilerplate code has still to be created, making the developer spending more time in UI than in accelerator physics code. In this paper a new approach in developing Open XAL applications is explained. Here the developer is relieved of the UI-related common code code by using software tools, allowing him to visually design the flow of data and events between the various elements of the applications (widgets and models), and automatically generate the application code, where code generation can be customized to use one of the available plugged programming languages (Java, Python, JS, …).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB137
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THPAB140	MAX IV Online Linac Model	4047
	L. Isaksson, E. Mansten, S. Thorin MAX IV Laboratory, Lund University, Lund, Sweden
	An online linac model has been developed at MAX IV in order to enable a calculation of the properties of the linac beam based on the actual settings of the magnetic elements. The model is based on the Elegant simulation code and uses the design linac lattice file. A set of Matlab scripts fetch the actual settings of all elements via the Tango control system, pass these values on to Elegant and run the simulation. The model includes an optimization option for yielding desired beta- and alpha-function values at various points along the linac by calculating optimal settings for chosen elements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB140
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THPAB141	Control and Operation of a Wideband RF System in CERN's PS Booster	4050
	M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Haase, M. Jaussi, J.C. Molendijk, M.M. Paoluzzi, J. Sanchez-Quesada CERN, Geneva, Switzerland
	A prototype wideband High-Level RF (HLRF) sys-tem based on Finemet metal alloy has been installed in CERN's PS Booster (PSB) Ring 4 in 2012, within the frame of the LHC Injectors Upgrade (LIU) project. A digital Low-Level RF (LLRF) system was used to control the HLRF system to ascertain the capabilities of the combined system, especially under heavy beam loading. The testing campaign was satisfactory and in 2015 the CERN management decided to replace all ferrite-based systems with Finemet ones for the PS Booster restart in 2020. This paper describes the LLRF features implemented for operating the wideband HLRF system and the main beam results obtained. Hints on the LLRF evolution in view of the PSB HLRF renovation are also given.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB141
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THPAB142	Initial Beam Results of CERN ELENA's Digital Low-Level RF System	4054
	M.E. Angoletta, S.C.P. Albright, S. Energico, S. Hancock, M. Jaussi, A.J. Jones, J.C. Molendijk, M.M. Paoluzzi, J. Sanchez-Quesada CERN, Geneva, Switzerland
	The Extra Low ENergy Antiproton (ELENA) decelerator is under commissioning at CERN. This decelerator is equipped with a new digital low-level RF (LLRF) system, in-house developed and belonging to the LLRF family already deployed in CERN's PS Booster and Low Energy Ion Ring (LEIR) synchrotrons. New features to adapt it to the demanding requirements of ELENA's operation include new, low noise ADC daughtercards and a fixed-frequency clocking scheme. This paper gives an overview of the LLRF system; initial beam results are also shown together with hints on the future system upgrade.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB142
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THPAB143	Operational Experience With the New Digital Low-Level RF System for CERN's PS Booster	4058
	M.E. Angoletta, S.C.P. Albright, A. Findlay, S. Hancock, M. Jaussi, J.C. Molendijk, J. Sanchez-Quesada CERN, Geneva, Switzerland
	The four rings of CERN's PS Booster have been equipped in 2014 with a new digital low-level RF (LLRF) system based upon a new, in-house developed LLRF family. This is a second-generation LLRF family that has been since then deployed on other synchrotrons. The paper provides an overview of the system's commissioning and first years of operation. In particular, an overview is given of the main system features and capabilities, such as beam loops and longitudinal beam blowup implementation. Operational improvements with respect to the previous, analogue digital LLRF are also mentioned, together with the planned system evolution to satisfy new requirements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB143
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THPAB144	The New LEIR Digital Low-Level RF System	4062
	M.E. Angoletta, S.C.P. Albright, A. Findlay, M. Haase, S. Hancock, M. Jaussi, J.C. Molendijk, M.M. Paoluzzi, J. Sanchez-Quesada CERN, Geneva, Switzerland
	CERN's Low Energy Ion Ring (LEIR) low-level RF (LLRF) system has been successfully upgraded in 2016 to the new digital, LLRF family for frequency-sweeping synchrotrons developed at CERN. For LEIR it implements not only beam loops but also the voltage and phase loops required for the control of two Finemet-based High-Level RF (HLRF) systems. This paper gives an overview of the system and of new requirements implemented, such as the parallel operation of two HLRF systems. Beam results for the 2016 lead ions run are also shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB144
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THPAB145	CERN Accelerators Topology Configuration: Facing the Next Long Shutdown	4066
	S. Bartolome-Jimenez, T.W. Birtwistle, S. Chemli, N. Gilbert, A.-L. Perrot, J. Piar, V. Simetka, B. Vazquez de Prada Planas CERN, Geneva, Switzerland
	The Configuration and Layout (CL) team at CERN ensures that there is a clear and coherent representation of the status of the CERN underground facilities (about 60 km of equipment) and main accelerator projects at a given point in time. In view of the major equipment changes to be carried out during the extended end of year technical stop (EYETS), the next Long Shutdown (LS2), and to facilitate the associated preparatory work of multiple CERN groups, the CL team has developed an immersive visualisation tool, displaying 360 degree panoramic images of CERN underground facilities. In addition, the CL team is launching a process to manage future layout configurations inside the CERN Layout database in parallel to the current configuration. This paper presents the 360 degree panorama visualisation tool and the parallel configuration process, to view the past, current and future status of the CERN accelerator complex. It highlights their added value for the CERN groups in the preparatory phase for upgrade and consolidation modifications and discusses the potential future improvements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB145
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THPAB146	Investigation of the Remanent Field of the SPS Main Dipoles and Possible Solutions for Machine Operation	4069
	F.M. Velotti, H. Bartosik, J. Bauche, M.C.L. Buzio, K. Cornelis, M.A. Fraser, V. Kain CERN, Geneva, Switzerland
	The CERN Super Proton Synchrotron (SPS) provides different types of beams at different extraction energies. The main magnets of the SPS are regulated with a current loop, but it has turned out that hysteresis effects from the main dipoles have a significant impact on reproducibility and hence efficiency and availability. Beam and machine parameters were found to depend on the programmed sequence of magnetic cycles - the so-called super cycle - representing the production of the different beams. The scientific program of the SPS requires frequent changes of the supercycle composition and the effect of the main magnet hysteresis has to be understood, modelled and used in accelerator control system. This paper summarises the first main field measurements carried out with the currently available systems during operational conditions as well as measurements of vital machine and beam parameters as a function of the super cycle composition. Finally, ideas will be presented to provide reproducibility by automatically correcting different parameters taking the magnetic history of the main magnets into account.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB146
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THPAB147	Automatic Local Aperture Measurements in the SPS	4073
	V. Kain, H. Bartosik, S. Cettour Cave, K. Cornelis, F.M. Velottipresenter CERN, Geneva, Switzerland
	The CERN SPS (Super Proton Synchrotron) serves as LHC injector and provides beam for the North Area fixed target experiments. It is equipped with flat vacuum chambers to accommodate the large horizontal beam size required during transition crossing and slow extraction. At low energy, the vertical acceptance becomes critical with high intensity large emittance fixed target beams. Optimizing the vertical available aperture is a key ingredient to optimize transmission and reduce activation around the ring. Aperture measurements are routinely carried out after each shutdown. Global vertical aperture measurements are followed by detailed bump scans at the locations with the loss peaks. During the 2016 run a tool was developed to provide an automated local aperture scan around the entire ring. This allowed to establish detailed reference measurements of the vertical aperture and identify directly the SPS aperture bottlenecks. The methodology applied for the scans will be briefly described in this paper and the analysis discussed. Finally, the 2016 SPS measured vertical aperture will be presented and compared to the results obtained with the previous method.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB147
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THPAB148	DIGITAL LOW LEVEL RF CONTROL SYSTEM FOR THE TAIWAN PHOTON SOURCE	4077
	F.Y. Chang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Z.K. Liu, C.H. Lo, C.L. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yupresenter NSRRC, Hsinchu, Taiwan
	The Taiwan Photon Source (TPS) is a 3 GeV, 500 mA, 499.65 MHz, 3rd generation synchrotron light source at NSRRC. To achieve the requirements of system flexibil-ity, fault diagnosis, precise control and high noise reduc-tion, a digital low level RF (DLLRF) control system based on Field Programmable Gate Array (FPGA) was developed. The communication interface is based on Raspberry Pi. The feedback loop performance of the control system was tested on the booster of the Taiwan Photon Source (TPS) with 950 kV gap voltage.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB148
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THPAB149	Characterization of the THz Radiation-Based Bunch Length Measurement System for the NSRRC Photoinjector	4080
	C.C. Liang, B.Y. Chen, C.H. Chenpresenter, M.C. Chou, S. Fann, C.S. Huang, N.Y. Huang, J.-Y. Hwang, W.K. Lau, A.P. Lee, T.Y. Lee, W.Y. Lin, T.-C. Yu NSRRC, Hsinchu, Taiwan
	A part of high brightness photo-injection (HBI) project at NSRRC is intending to adopt Coherent Transition Radiation (CTR) and Coherent Undulator Radiation (CUR) to generate THz radiation with an ultrashort electron bunch. Such high intensity THz sources allow the THz spectrum to be conducted easily with a THz interferometer and a Golay cell detector. Furthermore, the radiation spectrum carries information of the electron distribution which allows ultrashort electron bunch length measurements. For verifying correct measuring procedure during the CTR and CUR experiments, a conventional THz radiation generated by optical rectification from a ZnTe crystal has been performed. The produced THz pulse was sent into a Michelson interferometer which is designed for the autocorrelation of the intense, sub-mm and mm-wavelength, spatially-coherent radiation pulses. The THz spectrum can be further obtained from the interferogram by the Fourier transform process. In such way, the THz spectrum can be investigated if the result is satisfactory and can be applied on the THz CTR and CUR experiments for the next step.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB149
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THPAB150	Input Output Controller of Digital Low Level RF System in NSRRC	4083
	Z.K. Liu, F.Y. Chang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, C.H. Lo, C.L. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yupresenter NSRRC, Hsinchu, Taiwan
	Low Level Radio Frequency (LLRF) systems operating at NSRRC are based on analog technology and are used both at the Taiwan Light Source and the Taiwan Photon Source. In order to have better RF field stability, a new digital LLRF system based on Field Programmable Gate Array (FPGA) was developed. A card-sized single-board computer is used as the input/output controller of the digital LLRF system and its design and implementation with EPICS applications are reported here.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB150
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THPAB151	Online Optimisation Applications at SPS	4086
	T. Pulampong, P. Klysubun, S. Kongtawong, S. Krainara, P. Sudmuang SLRI, Nakhon Ratchasima, Thailand
	Optimisation of a particle accelerator with very limited diagnostic system is proved to be very challenging and complicated. Theoretical calculation and perfect machine model never guarantee the best solution in the actual machine. In this work, optimisation of injection system from Low energy Beam Transport line (LBT) to Siam Photon Source (SPS) storage ring and reduction of beam coupling employing Robust Conjugate Direction Search (RCDS) algorithm are demonstrated. New record improvement on injection efficiency and better coupling control will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB151
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THPAB152	Digital Low Level RF Systems for Diamond Light Source	4089
	P. Gu, C. Christou, P. Hamadyk, D. Spink, I.S. Uzun DLS, Oxfordshire, United Kingdom E. Morales, F. Pérez, A. Salom ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	Analogue low level RF (LLRF) systems have been used to date for both Diamond storage ring and booster RF cavities. They have been in operation for nearly ten years without a major problem. However, digital LLRF can offer new desirable functionalities such as fast data logging, 'probe blip' blockage and automation of routine tasks. Better performance is also envisaged with up to date hardware. A digital LLRF system has been developed with Alba Synchrotron as a common platform for the storage ring and booster, including superconducting and normal conducting RF cavities. The new digital LLRF is based on Virtex6 FPGA and fast ADCs and DACs. One system has been built and verified in the Diamond booster with beam. The design will be implemented for all other Diamond RF cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB152
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THPAB153	An Online Multi-Objective Optimisation Package	4092
	I.P.S. Martin, M. Apollonio, R. Bartolini, M.J. Furseman DLS, Oxfordshire, United Kingdom R. Bartolini, G.A. Bird JAI, Oxford, United Kingdom D.R. Obee Durham University, Durham, United Kingdom
	The overall performance of an electron storage ring is critically dependant on a large number of variables. It can be characterised in many ways, such as by lifetime, injection efficiency, beam stability and so on. It is frequently the case however that improving one parameter comes at the cost of harming another. Equally, given the large number of variables involved in optimising the ring performance, the true, global optimum solution may be difficult to identify using simple parameter scans. In order to address this problem, a flexible optimisation tool has been developed. This tool is capable of optimising several parameters at once and can cope with an arbitrary number of variables (individually or in families). The tool is designed to be robust to measurement noise, and has been applied to a number of different optimisation problems. This paper presents an overview of the package, as well as the results of the first tests.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB153
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THPAB154	Mechanical Design of Compact Vertical and Horizontal Linear Nanopositioning Flexure Stages With Centimeter-Level Travel Range for X-Ray Beamline Instrumentation	4096
	D. Shu, J.W.J. Anton, S.P. Kearney, B. Lai, W. Liu, J. Maser, C. Roehrig, J.Z. Tischler ANL, Argonne, Illinois, USA J.W.J. Anton University of Illinois at Chicago, Chicago, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. Nanopositioning techniques present an important capability to support the state-of-the-art x-ray instrumentation research for the APS operations and upgrade project. To overcome the performance limitations of precision ball-bearing-based or roller-bearing-based linear stage systems, compact vertical and horizontal linear nanopositioning flexure stages have been designed and developed at the APS with centimeter-level travel range and nanometer-level resolution for x-ray beamline instrumentation. Using improved deformation compensated linear guiding mechanisms [*,**], the APS T8-55 vertical linear flexure stage and T8-56 horizontal linear flexure stage are initially designed as a pair of sample scanning stages for a hard x-ray scanning microscope at the APS sector 2. Due to their unique repeatable nanopositioning performance over the centimeter-level travel range, these stages are also suitable for many photon beam lines optics with repeatable and stable nanopositioning requirements. The mechanical design and finite element analyses of the APS T8-55 and T8-56 flexural stages, as well as its initial mechanical test results with laser interferometer are described in this paper. * D. Shu, W. Liu, S. Kearney, J. Anton, B. Lai, J. Maser, C. Roehrig, and J. Z. Tischler, Proceedings of MEDSI-2016, Sept. 11-16, 2016, Barcelona, Spain. ** U.S. Patent granted No. 8,957, 567, D. Shu, S. Kearney, and C. Preissner, 2015.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB154
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THPAB155	Photoinjector Optimization Using a Derivative-Free, Model-Based Trust-Region Algorithm for the Argonne Wakefield Accelerator	4100
SUSPSIK069	use link to see paper's listing under its alternate paper code
	N.R. Neveu IIT, Chicago, Illinois, USA J.M. Larson, J.G. Power ANL, Argonne, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: DE-SC0015479, DE-AC02-06CH11357, DE-AC02-06CH11357 Model-based, trust-region, derivative-free algorithms are increasingly popular for optimizing computationally expensive numerical simulations. A strength of such methods is their efficient use of function evaluations. In this paper, we use one such algorithm to optimize the beam dynamics in two cases of interest at the Argonne Wakefield Accelerator (AWA) facility. First, we minimize the emittance of the electron bunch produced by the AWA drive rf photocathode gun alone by adjusting three parameters: rf gun phase, solenoid strength, and laser radius. The algorithm used converges to a set of parameters with an emittance of 1.08 mm-mrad. Second, we expand the number of optimization parameters to model the complete AWA rf photoinjector linac (the gun and six accelerating cavities). These results are used in a Pareto study of the trade-off between beam emittance and bunch length for the AWA linac.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB155
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