IPAC2015 - List of Keywords (plasma)

Paper	Title	Other Keywords	Page
MOAC1	Awake: the Proof-of-principle R&D Experiment at CERN	proton, laser, electron, experiment	34
	P. Muggli MPI, Muenchen, Germany M. Bernardini, T. Bohl, C. Bracco, A.C. Butterworth, S. Cipiccia, H. Damerau, S. Döbert, V. Fedosseev, E. Feldbaumer, E. Gschwendtner, W. Höfle, A. Pardons, A.V. Petrenko, J.S. Schmidt, M. Turner, H. Vincke CERN, Geneva, Switzerland
	The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) is a proof-of-principle R&D experiment at CERN. It is the world’s first proton driven plasma wakefield acceleration experiment, using a high-energy proton bunch to drive a plasma wakefield for electron beam acceleration. The AWAKE experiment will be installed in the former CNGS facility and uses the 400 GeV proton beam bunches from the SPS, which will be sent to a plasma source. An electron beam will be injected into the plasma cell to probe the accelerating wakefield. Challenging modifications in the area and new installations are required for AWAKE. First proton beam to the experiment is expected late 2016. The accelerating electron physics will start late 2017. This paper gives an overview of the project from a physics and engineering point of view, it describes the main activities, the milestones, the organizational set-up for the project management and coordination.
	Slides MOAC1 [21.632 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOAC1
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWA003	Optimal Generalized Finite Difference Solution to the Particle-in-Cell Problem	framework, simulation, space-charge, factory	77
	X. Wang, X. Jiao, H. Liu, V. Samulyak, K. Yu SBU, Stony Brook, USA V. Samulyak BNL, Upton, Long Island, New York, USA
	The particle-in-cell (PIC) method is widely used in applications, such as in electromagnetics, but the accuracy of its solutions degrades when the particle distribution is highly non-uniform. In our work, we propose an adaptive PIC method with optimal point distribution and a generalized finite difference (GFD) scheme. Our method replaces the Cartesian grid in the classical PIC with adaptive computational nodes or particles, to which the charges from the sample particles are assigned by a weighted least-square approximations. The partial differential equation is then discretized using a GFD method and solved with fast linear solvers. The density of computational particles is chosen adaptively, so that the error from GFD and that from Monte Carlo integration are balanced and the total error is approximately minimized. We also present the verification results using electrostatic problems and comparison of accuracy and solution time of our method with the classical PIC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA003
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWA042	Sub-fs Electron Bunch Generation Using Magnetic Compressor at SINBAD	electron, simulation, acceleration, laser	207
	J. Zhu, R.W. Aßmann, U. Dorda, J. Grebenyuk, B. Marchetti DESY, Hamburg, Germany
	In order to achieve high quality electron beams by laser-driven plasma acceleration with external injection, sub-fs bunches with a few fs arrival-time jitter are required. SINBAD (Short Innovative Bunches and Accelerators at DESY) is a proposed dedicated accelerator research and development facility at DESY. One of the baseline experiment at SINBAD is ARES (Accelerator Research Experiment at SINBAD), which will provide ultra-short electron bunches of 100 MeV to one or two connected beam lines. We present start-to-end simulation studies of sub-fs bunches generation at ARES using a magnetic compressor with a slit. In addition, the design of a dogleg with tunable R56 for the second beamline is also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA042
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWA048	Transverse Emittance Measurement for Low Energy Ion Beams Using Quadrupole Scan Method	ion, emittance, ion-source, ECR	226
	S. Kumar, A. Mandal IUAC, New Delhi, India
	Low energy ion beam facility (LEIBF) * at IUAC consists of all permanent magnet 10 Ghz electron cyclotron resonance (ECR) ion source (NANOGUN) along with 400 kV high voltage accelerating platform, a switching cum analysing magnet and electrostatic quadrupoles. Higher beam currents of heavy charge states and low energy of ion beams puts tremendous challenge to transport the ion beam from source to target. The normalized emittance of analysed ion beam is measured for specific charge to mass ratio using electrostatic quadrupole scan method * for various source parameters like RF power and injection pressure of gas etc. For various m/q ratios, the normalized transverse emittance ranges from 0.1 to 0.6 mm-mrad. It is attributed to beam rotation induced by ECR axial magnetic field, effect of ion temperature in plasma, non linear electric fields and space charge etc which play a significant role in emittance growth. * A. Mandal et. al. Proceedings of IPAC2011, WEPC011, San Sebastián, Spain D Kanjilal et. al. Indian J. Pure Appl. Phys. 39 (2001) 25 * I. G. Brown:The physics and technology of ion sources
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA048
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE022	Physical Model of Partial RF Discharge in Isochronous Cyclotrons	electron, cyclotron, ion, ion-source	323
	V.S. Dyubkov MEPhI, Moscow, Russia S. Korenev Siemens Medical Solutions Molecular Imaging, Knoxville, TN, USA
	The physical model for the partial RF discharge - based on the ionization of molecules of residual gas by electron detachment as a result of the electro-dissociation of negative hydrogen ions in isochronous cyclotrons - is proposed in this paper. The result of the simulation of the ionization of gas molecules by these electrons using RF voltage inside the Eclipse cyclotron (kinetic energy of 11 MeV) is presented. The analysis of the conductivity of the RF plasma (partial RF discharge) is given. The influence of the magnetic field on the properties of the partial RF discharge is discussed. The application of this model is for isochronous cyclotrons with low kinetic energy (10^-15 MeV).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE022
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE023	3D Computer Simulations of the Ultrarelativistic Beam Dynamics in Super Colliders	simulation, collider, focusing, experiment	326
	M.A. Boronina, V.A. Vshivkov ICM&MG SB RAS, Novosibirsk, Russia G. Dudnikova ICT SB RAS, Novosibirsk, Russia
	Funding: The work is supported by RFBR Grants 14-01-31088, 14-01-00392, 14-07-00241. The problem of numerical modeling of beam-beam interaction with high relativistic factor (~10⁴) is considered. We present 3D a self-consistent simulation model based on particle-in-cell method. The mixed Euler-Lagrangian decomposition is used in parallel algorithm for achieving good load balancing and reducing communication cost. Stable regimes of beam dynamics, depending on the beams configuration (beta-function, emittance, energy, currents and relative offset) can be found on the base of the model. In the calculations we used 10⁸ particles on the grid 100x100x100, the number of processors depends highly on the beam shape. The Lomonosov Super Computer and Siberian Supercomputer Centre cluster were used to perform the presented simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE023
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE084	Particle-in-cell Simulations of a Plasma Lens at Daresbury Laboratory	focusing, emittance, simulation, experiment	518
	K. Hanahoe, O. Mete, G.X. Xia UMAN, Manchester, United Kingdom D. Angal-Kalinin, J.K. Jones STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom J.D.A. Smith TXUK, Warrington, United Kingdom
	Feasibility of a focusing element using the transverse fields provided by a plasma cell was studied numerically. In this paper, an experimental set up is proposed for various beam parameters available from the VELA and CLARA beam lines at Daresbury Laboratory. 2D simulation results from VSim, and expected results from planned measurement stations are presented. Field properties and the advantages and disadvantages of such an instrument compared to conventional focusing elements are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE084
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA024	A Parallel Particle-Particle, Particle-Mesh Solver for Studying Coulomb Collisions in the Code IMPACT-T	emittance, electron, simulation, space-charge	593
	C.E. Mitchell, J. Qiang LBNL, Berkeley, California, USA
	Funding: This work is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. In intense charged-particle beams, the presence of Coulomb collisions can result in growth of the beam slice energy spread and emittance that cannot be captured correctly using traditional particle-in-cell codes. Particle-particle, particle-mesh solvers take a hybrid approach, combining features of N-body and particle-in-cell solvers, to correctly capture the effect of short-range particle interactions with less computing time than direct N-body solvers. We describe the implementation and benchmarking of such a solver in the code IMPACT-T for beam dynamics applications.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA024
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA030	Multisymplectic Integrators for Accelerator Tracking Codes	space-charge, simulation, storage-ring, DTL	614
	S.D. Webb, D.L. Bruhwiler RadiaSoft LLC, Boulder, Colorado, USA
	It has been long understood that long time single particle tracking requires symplectic integrators to keep the simulations stable. In contrast, space charge has been added to tracking codes without much regard for this. Indeed, multisymplectic integrators are a promising new field which may lead to more stable and accurate simulations of intense beams. We present here the basic concept, through a spectral electrostatic field solve which is suitable for adapting into existing tracking codes. We also discuss the limitations of current algorithms, and suggest directions for future development for the next generations of high intensity accelerators.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA030
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA037	Electron Cloud Buildup and Dissipation Models For PIP-II	electron, simulation, proton, space-charge	626
	S.A. Veitzer, P. Stoltz Tech-X, Boulder, Colorado, USA
	Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499), and the SCiDAC-3 project (DE-SC0008920). Buildup of electron plasmas in accelerator cavities can cause beam degradation and limit performance in high-intensity circular particle accelerators. This is especially important in machines such as the LHC, and PIP-II, where mitigation techniques such as beam scrubbing in order to decrease the SEY are expensive and time consuming. Modeling of electron cloud buildup and dissipation can provide understanding as to the potential negative effects of electron clouds on beam properties, as well as estimates of the mitigation required to maintain accelerator performance and beam quality as accelerators move to higher intensity configurations. We report here on simulations of electron cloud buildup and dissipation for geometry, beam and magnetic field configurations describing the Recycler at Fermilab. We perform electrostatic simulations in 3D with VSim PIC, including the effects of space charge and secondary electrons. We quantify the expected survival rate of electrons in these conditions, and argue that improvements in reducing the SEY is unlikely to mitigate the electron cloud effects.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA037
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA044	Barrier Shock Compression with Longitudinal Space Charge	space-charge, simulation, emittance, electron	646
	B. Beaudoin, I. Haber, R.A. Kishek UMD, College Park, Maryland, USA
	Funding: This work is supported by the US Dept. of Energy, Office of High Energy Physics. Synchrotrons and storage rings routinely employ RF barrier buckets as a means of accumulating charge to increase the peak intensity and preserve longitudinal emittance while minimizing emittance growth [1-3]. This was shown in the main injector and recycler at Fermilab as well as the SIS-18 at GSI Helmholtz center for heavy ion research. The RF cavities typically used are ferrite loaded magnetic alloys with low Q to maximize bandwidth and generate single pulses, either as delta functions, triangular or half/full period sine waves. The University of Maryland Electron Ring (UMER) group is studying a novel scheme of bunch compression in the presence of longitudinal space charge. It has been analytically shown through 1-D computations that the presence of space-charge considerably improves the efficiency of the barrier compression by taking advantage of the shock-front that launches when the barrier moves into a space-charge dominated beam. In this paper, we summarize the initial results of the study.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA044
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA059	Lorentz boosted frame simulation of Laser wakefield acceleration using hybrid Yee-fft solver in quasi-3d geometry	simulation, laser, wakefield, acceleration	691
	P. Yu, A.W. Davidson, V.K. Decyk, W.B. Mori, A. Tableman, F.S. Tsung UCLA, Los Angeles, California, USA F. Fiuza, L.O. Silva, J. Vieira IPFN, Lisbon, Portugal R.A. Fonseca ISCTE - IUL, Lisboa, Portugal W. Lu, X.L. Xu TUB, Beijing, People's Republic of China
	We present results from a preliminary study on modeling Laser wakefield acceleration (LWFA) with OSIRIS in a Lorentz boosted frame using a quasi-3D algorithm. In the quasi-3D algorithm, the fields and currents are expanded into azimuthal harmonics and only a limited number of harmonics are kept. Field equations in (r,z) space are solved for a desired number of harmonics in φ. To suppress the numerical Cerenkov instability (NCI) that inevitably arises due to the relativistic plasma drift in the simulation, we use a hybrid Yee-FFT solver in which the field equations are solved in (k_z, r) space, where \hat{z} is the drifting direction. Preliminary results show that high fidelity LWFA boosted frame simulations can be carried out with no evidence of the NCI. Good agreement is found when comparing LWFA boosted frame simulations in the full 3D geometry against those in the quasi-3D geometry. In addition, we discuss how the moving window can be combined with the hybrid Yee-FFT solver to further speed up the simulation. The results indicate that unprecedented speed ups for LWFA simulations can be achieved when combining the Lorentz boosted frame technique, the quasi-3D algorithm, and a moving window.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA059
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMN012	SPACE Code for Beam-Plasma Interaction	simulation, ion, electron, electromagnetic-fields	728
	K. Yu, V. Samulyak SBU, Stony Brook, USA V. Samulyak BNL, Upton, Long Island, New York, USA
	A parallel particle-in-cell code SPACE has been developed for the simulation of electromagnetic fields, relativistic particle beams, and plasmas. The algorithms include atomic processes in the plasma, proper boundary conditions, an efficient method for highly-relativistic beams in non-relativistic plasma, support for simulations in relativistic moving frames, and special data transfer algorithm from the moving to the laboratory frame that collects particles and fields in the lab frame without time shift due to the Lorentz transform, enabling data analysis and visualization. Plasma chemistry algorithms implement atomic physics processes such as the generation and evolution of plasma, recombination of plasma, and electron attachment on dopants in dense neutral gas. Benchmarks and experimental validation tests are also discussed. The code has been used for the simulation of processes relevant to the eRHIC program at BNL and the high pressure RF cavity (HPRF) program at Fermilab.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN012
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMN013	Simulation of Beam-Induced Plasma in Gas Filled Cavities	ion, simulation, cavity, electron	731
	K. Yu, V. Samulyak SBU, Stony Brook, USA M. Chung UNIST, Ulsan, Republic of Korea B.T. Freemire IIT, Chicago, Illinois, USA V. Samulyak BNL, Upton, Long Island, New York, USA A.V. Tollestrup, K. Yonehara Fermilab, Batavia, Illinois, USA
	Understanding of the interaction of muon beams with plasma in muon cooling devices is important for the optimization of the muon cooling process. SPACE, a 3D electromagnetic particle-in-cell (EM-PIC) code, is used for the simulation support of the experimental program on the hydrogen gas filled RF cavity in the Mucool Test Area (MTA) at Fermilab. We have investigated the plasma dynamics in the RF cavity including the process of power dump by plasma (plasma loading), recombination of plasma, and plasma interaction with dopant material. By comparison with experiments in the MTA, simulations suggest several unknown properties of plasma such as the effective recombination rate, the electron attachment time on dopant molecule, and the ion - ion recombination rate in the plasma.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN013
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMN015	Simulation of Beam-Induced Plasma for the Mitigation of Beam-Beam Effects	proton, simulation, electron, beam-beam-effects	734
	J. Ma, V. Samulyak, K. Yu SBU, Stony Brook, New York, USA V. Litvinenko, V. Samulyak, G. Wang BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA V. Samulyak SUNY SB, Stony Brook, New York, USA
	One of the main challenges in the increase of luminosity of circular colliders is the control of the beam-beam effect. In the process of exploring beam-beam mitigation methods using plasma, we evaluated the possibility of plasma generation via ionization of neutral gas by proton beams, and performed highly resolved simulations of the beam-plasma interaction using SPACE, a 3D electromagnetic particle-in-cell code. The process of plasma generation is modelled using experimentally measured cross-section coefficients and a plasma recombination model that takes into account the presence of neutral gas and beam-induced electromagnetic fields. Numerically simulated plasma oscillations are consistent with theoretical analysis. In the beam-plasma interaction process, high-density neutral gas reduces the mean free path of plasma electrons and their acceleration. A numerical model for the drift speed as a limit of plasma electron velocity was developed. Simulations demonstrate a significant reduction of the beam electric field in the presence of plasma. Preliminary simulations using fully-ionized plasma have also been performed and compared with the case of beam-induced plasma.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN015
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPHA026	Present and Future Optical-to-Microwave Synchronization Systems at REGAE Facility for Electron Diffraction and Plasma Acceleration Experiments	laser, electron, detector, timing	833
	M. Titberidze, F.J. Grüner, A.R. Maier, B. Zeitler CFEL, Hamburg, Germany S.W. Epp MPSD, Hamburg, Germany M. Felber, K. Flöttmann, T. Lamb, U. Mavrič, J.M. Müller, H. Schlarb, C. Sydlo DESY, Hamburg, Germany F.J. Grüner, A.R. Maier, M. Titberidze Uni HH, Hamburg, Germany E. Janas Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
	Relativistic Electron Gun for Atomic Explorations (REGAE) is a Radio Frequency (RF) driven linear accelerator. It uses frequency tripled short photon pulses (~ 35 fs) from the Titanium Sapphire (Ti:Sa.) Laser system in order to generate electron bunches from the photo-cathode. The electron bunches are accelerated up to ~ 5 MeV kinetic energy and compressed down to sub-10 fs using the so called ballistic bunching technique. REGAE currently is used for electron diffraction experiments (by Prof. R.J.D. Miller's Group). In near future within the collaboration of Laboratory for Laser- and beam-driven plasma Acceleration (LAOLA), REGAE will also be employed to externally inject electron bunches into laser driven linear plasma waves. Both experiments require very precise synchronization (sub-50 fs) of the photo-injector laser and RF reference. In this paper we present experimental results of the current and new optical to microwave synchronization systems in comparison. We also address some of the issues related to the current system and give an upper limit in terms of its long-term performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA026
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI015	A Low Time-Dispersion Refractive Optical Transmission Line for Streak Camera Measurements	electron, experiment, database, resonance	1178
	J.G. Power, G. Ha ANL, Argonne, Illinois, USA G. Ha POSTECH, Pohang, Kyungbuk, Republic of Korea
	Funding: Work supported by the U.S. Department of Energy office of High Energy Physics. Streak camera measurements of the charge particle bunch length are limited in resolution due to several factors: (1) the light from the source (optical transition radiation, Cherenkov, synchrotron radiation, etc.); (2) time dispersion introduced in the optical transmission line between the source and the streak camera; and finally (3) the streak camera resolution. The limiting resolution usually arises from the optical transmission line. While an all-reflective transmission line can eliminate dispersion, the system is complicated and expensive. In this paper, we consider how to design a refractive optical transport line to minimize the time dispersion while maximizing the signal. We present a theoretical model of the dispersion, modeling, and measurements of the time dispersion for several different lens materials.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI015
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI018	New Hadron Monitor By Using A Gas-Filled RF Resonator	electron, hadron, proton, radiation	1189
	K. Yonehara, A.V. Tollestrup, R.M. Zwaska Fermilab, Batavia, Illinois, USA G. Fasce CNI, Roma, Italy G. Flanagan, R.P. Johnson Muons, Inc, Illinois, USA
	It is trend to build an intense neutrino beam facility for the fundamental physics research, e.g. LBNF at Fermilab, T2K at KEK, and CNGS at CERN. They have investigated a hadron monitor to diagnose the primary/secondary beam quality. The existing hadron monitor based on an ionization chamber is not robust in the high-radiation environment vicinity of MW-class secondary particle production targets. We propose a gas-filled RF resonator to use as the hadron monitor since it is simple and hence radiation robust in this environment. When charged particles pass through the resonator they produce ionized plasma via the Coulomb interaction with the inert gas. The beam-induced plasma changes the permittivity of inert gas. As a result, a resonant frequency in the resonator shifts with the amount of ionized electrons. The radiation sensitivity is adjustable by the inert gas pressure and the RF amplitude. The hadron profile will be reconstructed with a tomography technique in the hodoscope which consists of X, Y, and theta layers by using a strip-shaped gas resonator. The sensitivity and possible system design will be shown in this presentation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI018
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI052	Responsivity Study of Diamond X-ray Monitors with nUNCD Contact	photon, synchrotron, detector, database	1273
	M. Gaowei, J. Smedley BNL, Upton, Long Island, New York, USA E.M. Muller, T. Zhou SBU, Stony Brook, New York, USA A.V. Sumant Argonne National Laboratory, Center for Nanoscale Materials, Argonne, USA
	Nitrogen doped ultrananocrystalline diamond (nUNCD) grown on the surface of a CVD single crystal diamond is tested at various beamlines covering an x-ray photon energy range of 200eV to 28 keV. The nUNCD has much lower x-ray absorption than metal contacts and is designed to improve the performance of our device. The responsivity of nUNCD diamond x-ray detector is compared with the conventional platinum coated diamond x-ray beam position monitor and the results are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI052
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUYC2	Multi-GeV Plasma Acceleration Results at BELLA	laser, electron, experiment, injection	1319
	A.J. Gonsalves, C. Benedetti, S.S. Bulanov, J. Daniels, E. Esarey, C.G.R. Geddes, H.S. Mao, D.E. Mittelberger, K. Nakamura, C.B. Schroeder, C. Tóth, J. van Tilborg LBNL, Berkeley, California, USA W. Leemans UCB, Berkeley, California, USA
	Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231 Laser-plasma accelerators (LPAs)* are being investigated as a compact driver for light sources and high-energy linear colliders. Recently 2 GeV beams were generated by focusing ≈ 100 J laser pulses onto a gas target. We report here on the generation of beams with energy up to 4.2 GeV using 16 J of laser pulse energy at the BErkeley Lab Laser Accelerator (BELLA). This was achieved by using laser pulses of high spatial and temporal quality coupled to a pre-formed capillary discharge waveguide of length 9 cm. The waveguide (in conjunction with self-guiding) allowed for mitigation of diffraction. High spatial quality (Strehl ratio at focus 0.8±0.1) was achieved using a deformable mirror placed before the focusing optic. The dominant contribution to the non-Gaussian content of the focal spot was the near-field intensity profile. For maximum efficiency high-power femtosecond systems employ super-Gaussian near-field profiles of the form I(r)∝e^-2(r/w^N), where I is the intensity, r is the radial coordinate, w is the spot size, and N is the order. Compared with Gaussian laser pulses where N=2, pulses from the BELLA laser system had N=10. Simulations showed that an increased contribution of self-guiding was required to effectively confine the laser energy for optimum acceleration and mitigation of damage to the capillary waveguide. Through appropriate choice of plasma density electron beams with energy up to 4.2 GeV were observed. In this regime the electron beam angular fluctuations were > 2 mrad rms, caused in part by errors in waveguide alignment and by laser-induced damage to the capillary that introduces plasma asymmetry. Improved alignment of the waveguide and mitigation of capillary damage allowed for reduction in angular fluctuations to 0.6 mrad rms. The electron beams had energy of 2.7±0.1 GeV, charge of 150 pC, and divergence less than 1 mrad. E. Esarey, et al., Rev. Mod. Phys. 81, 1229 (2009) X. Wang, et al., Nat. Communications 4, 1988 (2013) * W. P. Leemans, et al., Phys. Rev. Lett. 113, 245002 (2014)
	Slides TUYC2 [13.023 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUYC2
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUBB1	Charge Stripper Development for FRIB	ion, heavy-ion, proton, linac	1339
	F. Marti, P. Guetschow, J.A. Nolen FRIB, East Lansing, Michigan, USA A. Hershcovitch, P. Thieberger BNL, Upton, Long Island, New York, USA Y. Momozaki, J.A. Nolen, C.B. Reed ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and NSF grant PHY-1102511 The Facility for Rare Isotope Beams (FRIB) at Michigan State University is building a heavy ion linac to produce rare isotopes by the fragmentation method. The linac will accelerate ions up to U to energies above 200 MeV/u with beam powers up to 400 kW. At energies between 16 and 20 MeV/u the ions will be stripped to higher charge states to increase the energy gain downstream in the linac. The main challenges in the stripper design are due to the high power deposited by the ions in the stripping media (~ 30 MW/cm³) and radiation damage if solids are used. For that reason self-recovering stripper media must be used. The baseline stripper choice is a high-velocity, thin film of liquid lithium with an alternative option of a helium gas stripper. We present in this paper the status of the R&D and construction of the final stripper. Extensive experimental work has been performed on both options.
	Slides TUBB1 [3.534 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUBB1
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA030	Compression of an Electron-bunch by Means of Velocity Bunching at ARES	bunching, electron, emittance, simulation	1472
	B. Marchetti, R.W. Aßmann, U. Dorda, J. Grebenyuk, J. Zhu DESY, Hamburg, Germany
	ARES is a planned linear accelerator for research and development in the field of production of ultra-short electron bunches. The goal of ARES is to produce low charge (0.2-50pC), ultra-short (from few fs to sub-fs) bunches, with improved arrival time stability (less than 10fs) for various applications, such as external injection for Laser Plasma Wake-Field acceleration. The ARES layout will allow to perform and compare different kind of conventional e-bunch compression techniques, such as pure velocity bunching, hybrid velocity bunching (i.e. velocity bunching plus magnetic compression) and pure magnetic compression with the slit insertion. This flexibility will allow to directly compare the different methods in terms of arrival time stability and local peak current. In this paper we present simulation results for the compression of an electron bunch with 0.5 pC charge. We compare the case of pure velocity bunching compression to the one of a hybrid compression using velocity bunching plus a magnetic compressor. M. Ferrario et al., Phys. Rev. Lett. 104, 054801 (2010). ** P. Emma et al., PRL 92 7 (2004).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA030
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA031	Compression of Train of Bunches with Ramped Intensity Profile at SPARC_LAB	linac, laser, cathode, electron	1476
	B. Marchetti DESY, Hamburg, Germany A. Bacci Istituto Nazionale di Fisica Nucleare, Milano, Italy E. Chiadroni, M. Ferrario, R. Pompili INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy
	The production and acceleration of train of bunches with variable spacing in the ps/sub-ps range having ramped intensity profile are interesting to drive a plasma wave in the so-called resonant Plasma Wake-Fields Acceleration (r-PWFA). At SPARC_LAB trains having a constant intensity profile have been produced for the first time by using a shaped photo-cathode laser combined with the use of the velocity bunching compression technique,,*. If the sub-bunches have ramped intensity, i.e. they have different charge density, the space charge force affects differently the development of the longitudinal phase space of each one of them during the compression. In this paper we present preliminary simulations for the compression of a ramped train of bunches. The differences between the beam dynamics for a train of bunches having constant intensity profile and the ramped train are underlined. We discuss also the possibility of properly tuning the shaping of the photocathode laser to balance the space charge effect. SLAC-PUB-3528 M. Ferrario et al., Phys. Rev. Lett. 104, 054801 (2010). * M. Ferrario et al. NIM A 637, S43-S46 (2011). **** E. Chiadroni et al., Rev. Sci. Instrum. 84, 022703
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA031
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA046	Facility Upgrade at PITZ and First Operation Results	gun, laser, operation, electron	1518
	A. Oppelt, P. Boonpornprasert, A. Donat, J.D. Good, M. Groß, H. Huck, I.I. Isaev, L. Jachmann, D.K. Kalantaryan, M. Khojoyan, W. Köhler, G. Koss, G. Kourkafas, M. Krasilnikov, O. Lishilin, D. Malyutin, J. Meissner, D. Melkumyan, M. Otevřel, M. Penno, B. Petrosyan, S. Philipp, M. Pohl, Y. Renier, T. Rublack, B. Schöneich, J. Schultze, F. Stephan, F. Tonisch, G. Trowitzsch, G. Vashchenko, R.W. Wenndorff DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria M. A. Bakr Assiut University, Assiut, Egypt C. Hernandez-Garcia JLab, Newport News, Virginia, USA G. Pathak Uni HH, Hamburg, Germany D. Richter HZB, Berlin, Germany
	The Photo Injector Test facility at DESY, Zeuthen site (PITZ), develops, optimizes and characterizes high brightness electron sources for free electron lasers like FLASH and the European XFEL. In the last year, the facility was significantly upgraded by the installation of a new normal conducting radio- frequency (RF) gun cavity with its new waveguide system for the RF feed, which should allow stable and reliable gun operation, as required for the European XFEL. Other relevant additions include beamline modifications for improving the electron beam transport through the PITZ accelerator, extending the beam-based measurement capabilities, and preparing the installation of a plasma cell. Furthermore, the laser hutch was re-arranged in order to be able to house an additional, new photo cathode drive laser system which should be able to produce 3D ellipsoidal laser pulses to further improve the electron beam quality. This paper describes in detail the aforementioned facility upgrades and reports on the first operation experience with the new gun setup.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA046
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY074	Muon Beam Emittance Evolution in the Helical Ionization Cooling Channel for Bright Muon Sources	emittance, collider, space-charge, simulation	2203
	K. Yonehara, C.Y. Yoshikawa Fermilab, Batavia, Illinois, USA C.M. Ankenbrandt, R.P. Johnson, S.A. Kahn Muons, Inc, Illinois, USA M. Chung UNIST, Ulsan, Republic of Korea Y.S. Derbenev, A.V. Sy JLab, Newport News, Virginia, USA B.T. Freemire IIT, Chicago, Illinois, USA
	The six-dimensional ionization cooling is essential to design a bright muon source. A geometry constraint is a challenge issue in a compact helical cooling channel (HCC). Especially, the HCC requires a large bore helical magnet and a compact helical RF system to incorporate the RF into the magnet chamber. A new emittance evolution has been designed to mitigate the geometry constraint. The HCC was functionally separated into three parts sections. The lattice at the initial section provides a large transverse acceptance by using a strong helical focus magnet. Once the transverse beam size is small enough to get into the compact RF the HCC lattice in the middle section generates a large longitudinal beta tune to dominate the longitudinal cooling. Consequently, the longitudinal emittance becomes smaller than the transverse one at the end of middle section. In the final section, the magnetic field strength is gradually reduced to match out the helical channel to the straight solenoid. As a result, the emittance exchange takes place and the final transverse emittance becomes smaller than the longitudinal one. The new emittance evolution scenario will be discussed in this presentation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY074
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWI059	Influence of Plasma Loading in a Hybrid Muon Cooling Channel	ion, electron, cavity, emittance	2381
	D. Stratakis BNL, Upton, Long Island, New York, USA B.T. Freemire IIT, Chicago, Illinois, USA K. Yonehara Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In a hybrid 6D cooling channel, cooling is accomplished by reducing the beam momentum through ionization energy loss in wedge absorbers and replenishing the momentum loss in the longitudinal direction with gas-filled rf cavities. While the gas acts as a buffer to prevent rf breakdown, gas ionization may also occur as the beam passes through a HPRF cavity. The resulting plasma, may gain substantial energy from the rf electric field which it can transfer via collisions to the gas, an effect known as plasma loading. In this paper, we investigate the influence of plasma loading on the cooling performance of a rectilinear hybrid channel. With the aid of numerical simulations we examine the sensitivity in cooling performance and plasma loading to key parameters such as the rf gradient and gas pressure.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI059
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA003	Simulations of Electron-Proton Beam Interaction before Plasma in the AWAKE Experiment	proton, electron, wakefield, quadrupole	2492
	U. Dorda, R.W. Aßmann, J. Grebenyuk DESY, Hamburg, Germany C. Bracco, A.V. Petrenko, J.S. Schmidt CERN, Geneva, Switzerland
	The on-axis injection of electron bunches in the proton-driven plasma wake at the AWAKE experiment at CERN implies co-propagation of a low-energy electron beam with the long high-energy proton beam in a common beam pipe over several meters upstream of the plasma chamber. The possible effects of the proton-induced wakefields on the electron bunch phase space in the common beam pipe region may have crucial implications for subsequent electron trapping and acceleration in plasma. We present the CST Studio simulations of the tentative common beam pipe setup and the two beam co-propagating in it. Simulated effects of the proton wakefields on electrons are analysed and compared to analytical predictions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA003
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA005	Simulations Study for Self-Modulation Experiment at PITZ	electron, wakefield, simulation, experiment	2496
	G. Pathak, F.J. Grüner Uni HH, Hamburg, Germany C. Benedetti, C.B. Schroeder LBNL, Berkeley, California, USA M. Groß, F. Stephan DESY Zeuthen, Zeuthen, Germany A. Martinez de la Ossa, T.J. Mehrling, J. Osterhoff DESY, Hamburg, Germany
	Self-modulation (SM) of proton beams in plasma has recently gained interest in context with the ongoing PWFA experiment of the AWAKE collaboration at CERN. Instrumental for that experiment is the SM of a proton beam to generate bunchlets for resonant wave excitation and efficient acceleration. A fundamental understanding of the underlying physics is vital, and hence an independent experiment has been set up at the beamline of the Photo Injector Test Facility at DESY, Zeuthen Site (PITZ), to study the SM of electron beams in a plasma. This contribution presents simulation results on SM experiments at PITZ using the particle-in-cell code HiPACE. The simulation study is crucial to optimize the beam and plasma parameters for the experiment. Of particular interest is the energy modulation imprinted onto the beam by means of the generated wakefields in the plasma. With the support of simulations the observation of this information in the experiment can be used to deduce key properties of the accelerating electric fields such as their magnitude and their phase velocity, both of significant importance for the design of self-modulated plasma-based acceleration experiments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA005
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA006	Laser Propagation Effects During Photoionization of Meter Scale Rubidium Vapor Source	laser, experiment, proton, wakefield	2499
	J.T. Moody, F. Batsch, A. Joulaei, P. Muggli, E. Öz MPI-P, München, Germany N. Berti, J. Kasparian University of Geneva, GAP Biophotonics, Carouge, Switzerland
	The baseline AWAKE experiment requires a 10 meter long plasma source with a density of 10¹⁵ cm􀀀^-3 and a density uniformity of 0.2%. To produce this plasma, a temperature stabilized rubidium vapor source is photoionized by a terawatt peak power laser pulse. In this paper we describe the laser pulse evolution within the plasma source including the dispersive, diffractive, and photoionization effects on the laser pulse. These calculations will be experimentally investigated in a meter long heat pipe oven using scaled laser parameters.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA006
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA007	The AWAKE Proton-driven Plasma Wakefield Experiment at CERN	electron, wakefield, injection, experiment	2502
	P. Muggli MPI-P, München, Germany
	Funding: For the AWAKE collaboration The AWAKE experiment at CERN * aims at studying plasma wakefield generation and acceleration driven by proton bunches. The first experiments will focus on the self-modulation instability of the long (~12cm, rms) proton bunch in the plasma. This instability is used to transform the incoming bunch into a train of short bunches with a period approximately equal to the plasma wavelength, ~1.2mm at a nominal plasma electron density of 7·10¹⁴/cc. These experiments are planned for the end of 2016. Later, low energy (~15MeV) electrons will be externally injected to sample the wakefields and be accelerated beyond 1GeV. The main goals of the experiment will be summarized and the progress with the plasma source, beam diagnostics and injection method will be presented. * AWAKE Collaboration, Plasma Phys. Control. Fusion 56 084013 (2014)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA007
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA008	Measuring the Self-modulation Instability of Electron and Positron Bunches in Plasmas	electron, cavity, radiation, positron	2506
	P. Muggli, O. Reimann MPI-P, München, Germany E. Adli, V.K.B. Olsen University of Oslo, Oslo, Norway J. Allen, S.J. Gessner, S.Z. Green, M.J. Hogan, M.D. Litos, B.D. O'Shea, V. Yakimenko SLAC, Menlo Park, California, USA L.D. Amorim IST, Lisboa, Portugal G. Andonian, C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi, O. Williams UCLA, Los Angeles, California, USA N.C. Lopes, L.O. Silva, J. Vieira Instituto Superior Tecnico, Lisbon, Portugal
	The self-modulation instability (SMI) * can be used to transform a long, charged particle bunch into a train of periodically spaced shorter bunches. The SMI occurs in a plasma when the plasma wake period is much shorter than the bunch length. The train of short bunches can then resonantly drive wakefields to much larger amplitude that the long bunch can. The SMI will be used in the AWAKE experiment at CERN, where the wakefields will be driven by a high-energy (400GeV) proton bunch. However, most of the SMI physics can be tested with the electron and positron bunches available at SLAC-FACET. * In this case, the bunch is ~10 plasma wavelengths long, but can drive wakefields in the GV/m range. FACET has a meter-long plasma **** and is well equipped in terms of diagnostic for SMI detection: optical transition radiation for transverse bunch profile measurements, coherent transition radiation interferometry for radial modulation period measurements and energy spectrometer for energy loss and gain measurement of the drive bunch particles. The latest experimental results will be presented. * N. Kumar et al., PRL 104, 255003 (2010) AWAKE Collaboration, PPCF 56 084013 (2014) * J. Vieira et al., PoP 19, 063105 (2012) **** S.Z. Green et al., PPCF 56, 084011 (2014)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA008
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA010	A High Intensity Proton Source for the European Spallation Source Facility	proton, emittance, extraction, site	2509
	L. Celona, L. Allegra, L. Andò, A.C. Caruso, G. Castro, F. Chines, G. Gallo, S. Gammino, A. Longhitano, S. Marletta, D. Mascali, L. Neri, S. Passarello, G. Torrisi INFN/LNS, Catania, Italy A. Longhitano ALTEK, San Gregorio (CATANIA), Italy G. Torrisi Universitá Mediterranea di Reggio Calabria, Reggio Calabria, Italy
	Along the last twentyfive years, INFN-LNS has gained a relevant role in R&D of plasma-based ion sources. The laboratory is currently involved in the Proton Source and Low Energy Beam Transport (LEBT) line prototype construction for the European Spallation Source. ESS – based on a 2.0 GeV, 62.5 mA proton accelerator for neutron production – will be a fundamental instrument for research and application. The proton source is required to produce at least 90 mA beam (as total drain current) at 0.25 π.mm.mrad emittance, 2.86 ms pulse duration, 14 Hz repetition rate. We will illustrate the advanced design of the machine, including the innovations in plasma heating schemes, the final layout of the LEBT – based on detailed beam transport studies, a new vacuum scheme and the final chopper strategy – and the first steps of the devices installation at the INFN-LNS test-bench site.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA010
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA012	Design of a Microwave Frequency Sweep Interferometer for Plasma Density Measurements in ECR Ion Sources	ion, simulation, diagnostics, ion-source	2512
	G. Torrisi, R. Agnello, G. Castro, L. Celona, V. Finocchiaro, S. Gammino, D. Mascali, L. Neri, S. Passarello INFN/LNS, Catania, Italy T. Isernia, G. Torrisi Universitá Mediterranea di Reggio Calabria, Reggio Calabria, Italy G. Sorbello University of Catania, Catania, Italy
	Electron Cyclotron Resonance Ion Sources (ECRIS) are among the candidates to support the growing request of intense beams of multicharged ions. Their further development is related to the availability of new diagnostic tools, nowadays consisting of few types only of devices designed on purpose for such compact machines. Microwave Interferometry is a non-invasive method for plasma diagnostics and represents the best candidate for the whole plasma density measurements. Interferometry in ECR Ion Sources is a challenging task due to their compact size. The typical density range of ECR plasmas (10¹¹-10¹² cm^-3) causes the probing beam wavelength to be in the order of few centimetres, which is comparable to the chamber radius. The paper describes the design of a new microwave interferometer based on the so-called "frequency sweep" method: the density is here derived by the frequency shift of a beating signal obtained during the fast sweep of both probing and reference microwave signals; inner cavity multipaths contributions can thereby be suppressed by cleaning the spurious frequencies from the beating signal spectrum.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA012
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA026	Loading of a Plasma-Wakefield Accelerator Section Driven by a Self-Modulated Proton Bunch	electron, proton, simulation, beam-loading	2551
	V.K.B. Olsen, E. Adli University of Oslo, Oslo, Norway L.D. Amorim IST, Lisboa, Portugal P. Muggli MPI, Muenchen, Germany J. Vieira Instituto Superior Tecnico, Lisbon, Portugal
	We investigate beam loading of a plasma wake driven by a self-modulated proton beam using particle-in-cell simulations for phase III of the AWAKE project. We address the case of injection after the proton beam has already experienced self-modulation in a previous plasma. Optimal parameters for the injected electron bunch in terms of initial beam energy and beam charge density are investigated and evaluated in terms of witness bunch energy and energy spread. An approximate modulated proton beam is emulated in order to reduce computation time in these simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA026
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA031	A Compact Multiply Charged Ion Source for Hadrontherapy Facility	ion, injection, ion-source, solenoid	2563
	L. Celona, L. Andò, G. Castro, F. Chines, G. Ciavola, S. Gammino, O. Leonardi, D. Mascali, L. Neri, D. Nicolosi, F. Noto, F. Romano, G. Torrisi INFN/LNS, Catania, Italy G. Ciavola CNAO Foundation, Milan, Italy G. Torrisi Universitá Mediterranea di Reggio Calabria, Reggio Calabria, Italy
	The ion sources, required by medical applications, must provide intense ion beams, with high reproducibility, stability and brightness. AISHa (Advanced Ion Source for Hadrontherapy) is a compact ECRIS whose hybrid magnetic system consists of a permanent Halbach-type hexapole magnet and a set of independently energized superconducting coils. These will be enclosed in a compact cryostat with two cryocoolers to operate without LHe. The microwave injection system has been designed for maximizing the beam quality through a fine frequency tuning within the 17.3-18.4 GHz band which is possible by using an innovative variable frequency klystron. The introduction of an integrated oven will allow the production of metal ions beams with relatively high intensity. “Accel-decel” extraction system will be used. The LEBT line will consist of a solenoid and a 90° dipole for ions selection. Two diagnostic boxes, made of Faraday cups, beam wires and slits, will allow the investigation of the beam composition and its properties. Moreover, a system of scintillating screens and CCD cameras, placed after the solenoid will allow the investigation of the Frequency Tuning Effect on the source performances.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA031
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA033	Characterization of Laser-plasma Accelerated Electron Beam for a Compact Storage Ring	laser, electron, target, storage-ring	2569
	S. H. Park, Y. Cha, Y.U. Jeong, J.S. Jo, H.N. Kim, K.N. Kim, K. Lee, W.J. Ryu, J.S. Shinn, N. Vinokurov KAERI, Daejon, Republic of Korea N. Vinokurov BINP SB RAS, Novosibirsk, Russia
	A compact radiation source can be utilized by an electron beam from a Laser-plasma acceleration combined with localized shielding in a small laboratory. The stability of synchrotron radiation in wavelength and power depends on the shot-to-shot jitters of the energy and charge of an electron beam, which is strongly influenced by the plasma density of target and the jitters of a laser beam. With the 30 TW fs laser in KAERI, the optimization for generating the electron beam have done using the different shape of gas nozzle. We also present the pointing stability and the energy spread of the laser-accelerated electron beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA033
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA039	The AWAKE Electron Primary Beam Line	electron, proton, dipole, wakefield	2584
	J.S. Schmidt, J. Bauche, B. Biskup, C. Bracco, E. Bravin, S. Döbert, M.A. Fraser, B. Goddard, E. Gschwendtner, L.K. Jensen, O.R. Jones, S. Mazzoni, M. Meddahi, A.V. Petrenko, F.M. Velotti, A.S. Vorozhtsov CERN, Geneva, Switzerland U. Dorda DESY, Hamburg, Germany L. Merminga, V.A. Verzilov TRIUMF, Vancouver, Canada P. Muggli MPI, Muenchen, Germany
	The AWAKE project at CERN is planned to study proton driven plasma wakefield acceleration. The proton beam from the SPS will be used in order to drive wakefields in a 10 m long Rb plasma cell. In the first phase of this experiment, scheduled in 2016, the self-modulation of the proton beam in the plasma will be studied in detail, while in the second phase an external electron beam will be injected into the plasma wakefield to probe the acceleration process. The installation of AWAKE in the former CNGS experimental area and the required optics flexibility define the tight boundary conditions to be fulfilled by the electron beam line design. The transport of low energy (10-20 MeV) bunches of 1.25·10⁹ electrons and the synchronous copropagation with much higher intensity proton bunches (3E11) determines several technological and operational challenges for the magnets and the beam diagnostics. The current status of the electron line layout and the associated equipments are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA039
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA041	Plans for a Linear Paul Trap at Rutherford Appleton Laboratory	multipole, quadrupole, ion, resonance	2590
	D.J. Kelliher, S. Machida, D.C. Plostinar, C.R. Prior, S.L. Sheehy STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	For over a decade, Linear Paul Traps (LPT) have been used in the study of accelerator beam dynamics. LPT studies exploit the similarity of the Hamiltonian with that of a beam in a quadrupole channel while having advantages in the flexibility of parameter choice, compactness and low cost. In collaboration with Hiroshima University, LPT research planned at STFC Rutherford Appleton Laboratory in the UK aims to investigate a range of topics including resonance crossing, halo formation, long-term stability studies and space-charge effects. Initially, a conventional quadrupole-based LPT will be built at RAL and used for a variety of experiments. In parallel, a design for a more advanced LPT that incorporates higher order multipoles will be pursued and later constructed. This multipole trap will allow non-linear lattice elements to be simulated and so broaden considerably the range of experiments that can be conducted. These will include the investigation of resonance crossing in non-linear lattices, a more detailed study of halo formation and the effect of detuning with amplitude. In this paper we report on progress made in the project to date and future plans.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA041
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA045	Development of a Spectrometer for Proton Driven Plasma Wakefield Accelerated Electrons at AWAKE	electron, dipole, proton, simulation	2601
	L.C. Deacon, S. Jolly, F. Keeble, M. Wing UCL, London, United Kingdom B. Biskup Czech Technical University, Prague 6, Czech Republic B. Biskup, E. Bravin, A.V. Petrenko CERN, Geneva, Switzerland M. Wing DESY, Hamburg, Germany M. Wing University of Hamburg, Hamburg, Germany
	The AWAKE experiment is to be constructed at the CERN Neutrinos to Gran Sasso facility (CNGS). This will be the first experiment to demonstrate proton-driven plasma wakefield acceleration. The 400 GeV proton beam from the CERN SPS will excite a wakefield in a plasma cell several metres in length. To observe the plasma wakefield, electrons of 10–20 MeV will be injected into the wakefield following the head of the proton beam. Simulations indicate that electrons will be accelerated to GeV energies by the plasma wakefield. The AWAKE spectrometer is intended to measure both the peak energy and energy spread of these accelerated electrons. Improvements to the baseline design are presented, with an alternative dipole magnet and quadrupole focussing, with the resulting energy resolution calculated for various scenarios. The signal to background ratio due to the interaction of the SPS protons with upstream beam line components is calculated, and CCD camera location, shielding and light transport are considered.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA045
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA047	Emittance Growth in a Plasma Wakefield Accelerator	emittance, electron, scattering, wakefield	2609
	Ö. Mete, K. Hanahoe, G.X. Xia UMAN, Manchester, United Kingdom M. Labiche STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	The interaction of the witness beam with the surrounding plasma particles and wakefields was studied. The implications of the elastic scattering process on beam emittance and, emittance evolution under the focusing and acceleration provided by plasma wakefields were discussed. Simulations results from GEANT4 are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA047
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA048	Design Studies and Commissioning Plans for PARS Experimental Program	acceleration, wakefield, electron, beam-loading	2612
	Ö. Mete, K. Hanahoe, J. Wright, G.X. Xia UMAN, Manchester, United Kingdom M. Dover, M. Wigram, J. Zhang University of Manchester, Manchester, United Kingdom J.D.A. Smith Tech-X, Boulder, Colorado, USA
	Funding: Science and Technology Facilities Council and Cockcroft Institute Core Grant PARS (Plasma Acceleration Research Station) is an electron beam driven plasma wakefield acceleration test stand proposed for VELA/CLARA facility in Daresbury Laboratory. In order to optimise various operational configurations, 2D numerical studies were performed by using VSIM for a range of parameters such as bunch length, radius, plasma density and positioning of the bunches with respect to each other for the two-beam acceleration scheme. In this paper, some of these numerical studies and considered measurement methods are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA048
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA059	RF Plasma-Based Ion Source Modeling on Unstructured Meshes	ion, simulation, ion-source, electron	2637
	S.A. Veitzer, K.R.C. Beckwith, M. Kundrapu Tech-X, Boulder, Colorado, USA
	Funding: This work was performed under the auspices of the Department of Energy, Office of Basic Energy Sciences Award #DE-SC0009585. Ion source performance for accelerators and industrial applications can be improved through detailed numerical modeling and simulation. There are a number of technical complexities with developing robust models, including a natural separation of important time scales (rf, electron and ion motion), inclusion of plasma chemistry, and surface effects such as secondary electron emission and sputtering. Due to these computational requirements, it is typically difficult to simulate ion sources with Particle-In-Cell codes. An alternative is to use fluid-based codes coupled with electromagnetics in order to model ion sources. These types of models can simulate plasma evolution and rf-driven flows while maintaining good performance. We show here recent results on modeling the H⁻ ion source for the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) using the fluid plasma modeling code USim. We present new meshing capabilities for generating and parallelizing unstructured computational meshes that have increased our parallel code performance and enabled us to model inductively coupled plasmas for long periods of operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA059
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA063	Beam-Plasma Effects in Muon Ionization Cooling Lattices	simulation, electron, space-charge, ion	2649
	J.S. Ellison, P. Snopok IIT, Chicago, Illinois, USA
	Funding: Work is supported by the U.S. Department of Energy. New computational tools are essential for accurate modeling and simulation of the next generation of muon based accelerator experiments. One of the crucial physics processes specific to muon accelerators that has not yet been implemented in any current simulation code is beam induced plasma effect in liquid, solid, and gaseous absorbers. We report here on the progress of developing the required simulation tools and applying them to study the properties of plasma and its effects on the beam in muon ionization cooling channels.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA063
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA068	Simulation of Laser Pulse Driven Terahertz Generation in Inhomogeneous Plasmas	radiation, laser, simulation, vacuum	2661
	C.M. Miao, T.M. Antonsen UMD, College Park, Maryland, USA J. Palastro Icarus Research, Inc., Bethesda, Maryland, USA
	Intense, short laser pulses propagating through inhomogeneous plasma can ponderomotively drive THz radiation. Here we consider a transition radiation mechanism (TRM) for THz generation as a laser pulse crosses a plasma boundary. Full format PIC simulations and theoretical analysis are conducted demonstrating that TRM results in low frequency, broad band, coherent THz radiation. The effect of a density ramp is also considered and shown to enhance the radiated energy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA068
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA072	Feasibility of Continuously Focused TeV/m Channeling Acceleration with CNT-Channel	acceleration, electron, wakefield, simulation	2670
	Y.-M. Shin Northern Illinois University, DeKalb, Illinois, USA A.H. Lumpkin, V.D. Shiltsev, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA
	Funding: This work was supported by the DOE contract No. DEAC02-07CH11359 to the Fermi Research Alliance LLC. Atomic channels in crystals are known to consist of 10 – 100 V/Å potential barriers capable of guiding and collimating a high energy beam and continuously focused acceleration with exceptionally high gradients (TeV/m),,. However, channels in natural crystals are only angstrom-size and physically vulnerable to high energy interactions. Carbon-based nano-crystals such as carbon-nanotubes (CNTs) and graphenes have a large degree of dimensional flexibility and thermo-mechanical strength, which could be suitable for channeling acceleration of MW beams. Nano-channels of the synthetic crystals can accept a few orders of magnitude larger phase-space volume of channeled particles with much higher thermal tolerance than natural crystals*. Our particle-in-cell simulations with 100 um long effective CNT model indicated that a beam-driven self-acceleration produces 1 – 2 % net energy gain in the quasi-linear regime (off-resonance beam-plasma coupling, np = 1000 nb) with ASTA 50 MeV injector beam parameters. This paper presents current status of CNT-channeling acceleration experiment planned at the Advanced Superconducting Test Accelerator (ASTA) in Fermilab. T. Tajima, PRL 59, 1440 (1987) P. Chen and R. Noble, slac-pub-4187 * Y. M. Shin, APL 105, 114106 (2014) **** Y.M. Shin, D. A. Still, and V. Shiltsev, Phys. Plasmas 20, 123106 (2013)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA072
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPJE001	Optimal Positron-Beam Excited Plasma Wakefields in Hollow and Ion-Wake Channels	electron, positron, wakefield, ion	2674
	A. A. Sahai, T.C. Katsouleas Duke ECE, Durham, North Carolina, USA
	Funding: DE-SC-0010012, NSF-PHY-0936278 A positron-beam interacting with the plasma electrons drives radial suck-in, in contrast to an electron-beam driven blow-out in the over-dense regime, n_b>n₀. In a homogeneous plasma, the electrons are radially sucked-in from all the different radii. The electrons collapsing from different radii do not simultaneously compress on-axis driving weak fields. A hollow-channel allows electrons from its channel-radius to collapse simultaneously exciting coherent fields . We analyze the optimal channel radius. Additionally, the low ion density in the hollow allows a larger region with focusing phase. We have shown the formation of an ion-wake channel behind a blow-out electron bubble-wake. Here we explore positron acceleration in the over-dense regime comparing an optimal hollow-plasma channel to the ion-wake channel . The condition for optimal hollow-channel radius is also compared. We also address the effects of a non-ideal ion-wake channel on positron-beam excited fields. S Lee, T Katsouleas, Phys. Rev. E, vol 64, 045501(R) (2001) ** A A Sahai, T Katsouleas, Non-linear ion-wake excitation by ultra relativistic electron wakefields, in review (http://arxiv.org/pdf/1504.03735v1.pdf)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE001
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPJE011	High Reliability, Long Lifetime, Continuous Wave H⁻ Ion Source	ion, ion-source, electron, extraction	2695
	P. Barrows, G.E. Becerra PNL, Madison, Wisconsin, USA
	Funding: Small Business Innovation Research (SBIR) Phase II Phoenix Nuclear Labs (PNL) is developing a high-current, long-lifetime negative hydrogen (H⁻) ion source in partnership with Fermilab as part of an ion beam injector for future Intensity Frontier particle accelerators. In this application, continuous output with long lifetime and high reliability and efficiency are critical. Existing ion sources at Fermilab rely on plasma-facing electrodes and are limited to lifetimes of a few hundred hours, while requiring relatively high gas loads on downstream components. PNL's H⁻ ion source uses an electrodeless microwave plasma generator which has been extensively developed in PNL's positive ion source systems, demonstrating 1000+ hours of operation and >99% continuous uptime. A magnetic filter preferentially blocks energetic electrons produced in the plasma, while allowing cold electrons and fast neutrals through toward a cesiated surface converter to produce the desired H⁻ ions, which are extracted into a low energy beam using electrostatic lenses. The design specifications are 5-10 mA of continuous H⁻ current at 30 keV with <0.2 pi-mm-mrad beam emittance. Construction and testing of the H⁻ ion source is underway at PNL.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE011
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPJE024	Progress on the Study of Direct Laser Electron Acceleration in Density-Modulated Plasma Waveguides	electron, laser, simulation, acceleration	2723
	M.W. Lin, B.W. Morgan The Pennsylvania State University, University Park, Pennsylvania, USA S.-H. Chen, C.-Y. Hsieh, Y.-L. Liu NCU, Chung Li, Taiwan I. Jovanovic Penn State University, University Park, Pennsylvania, USA
	Funding: This work is supported by the United States Defense Threat Reduction Agency through contract HDTRA1-11-1-0009 and the Ministry of Science and Technology in Taiwan by Grant No. MOST103-2112-M-008-004. Direct laser acceleration of electrons can be achieved by utilizing the axial field of a guided, radially polarized laser pulse in a density-modulated plasma waveguide. When a short fs electron bunch is injected, our particle-in-cell simulations show that the electrostatic field, arising from plasma electrons perturbed by the laser ponderomotive force, increases the transverse divergence of the bunch electrons. Simulations are performed to study the method in which a precursor electron bunch is introduced prior to the main accelerated bunch. The precursor induces a focusing electrostatic field in the background plasma, which can considerably reduce the transverse expansion of the accelerated electrons. Based on the ignitor-heater scheme, density-modulated plasma waveguides are produced in experiments with high-Z gas targets and used to test the guiding of laser pulses. Supersonic gas jet nozzles for producing gas targets are simulated, designed, and then fabricated via direct digital deposition manufacturing. Surface quality of the nozzles and the produced gas target density profiles are evaluated with computerized tomography and optical interferometry, respectively. A. G. York, et al., Phys. Rev. Lett. 100, 195001 (2008). ** M.-W. Lin et al., Phys. Plasmas 21, 093109 (2014)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE024
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA059	Degassing of Kicker Magnet by In-situ Bake-out Method	vacuum, kicker, radiation, shielding	2911
	J. Kamiya, Y. Hikichi, M. Kinsho, N. Ogiwara JAEA/J-PARC, Tokai-mura, Japan
	New method of in-situ degassing of the kicker magnet in the beam line has been developed. The heater and heat shielding panels are installed in the vacuum chamber in this method. The heater was designed considering the maintainability. The graphite was selected as the heater and the high melting point metals were used as the reflectors just near the heater. The thermal analysis and the temperature measurement with the designed heater was performed. The ideal temperature distribution for the kicker degassing was obtained. The outgassing of the graphite during rising the temperature was measured. The result showed that the outgassing was extremely suppressed by the first heating. This means the outgassing of the graphite heater was negligible as long as it is used in the beam line without exposure to the air.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA059
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA058	Superconducting Coatings Synthesized by CVD/PECVD for SRF Cavities	niobium, superconductivity, SRF, accelerating-gradient	3246
	P. Pizzol, P. Chalker, T. Heil The University of Liverpool, Liverpool, United Kingdom A.N. Hannah, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G.B.G. Stenning STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	Funding: STFC Bulk niobium cavities are widely employed in particle accelerators to create high accelerating gradient despite their high material and operation cost. In order to reduce this cost, thin layer of niobium are deposited on a copper cavity, which has lower material cost with higher availability and more importantly higher thermal conductivity. The coating of superconducting cavities currently is synthesized by physical vapour deposition (PVD) method which suffers from lack of conformity. By using chemical vapour deposition (CVD) and plasma enhanced chemical vapour deposition (PECVD) it is possible to deposit thin Nb layers uniformly with density very close to bulk material. This project explores the use of PECVD / CVD techniques to deposit metallic niobium on copper using NbCl5 as precursor and hydrogen as a coreagent. The samples obtained were then characterized via SEM, TEM, SAD, XRD, XPS, and EDX as well as assessing their superconductivity characteristics (RRR and Tc) All the samples deposited are superconductive and polycrystalline; the sample obtained with CVD measured RRR=31 and Tc=7.9 K, while the sample obtained with PECVD exhibited RRR=9 and Tc= 9.4 K. In both cases the films grew in a (100) preferred orientation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA058
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA059	Physical Vapour Deposition of Thin Films for Use in Superconducting RF Cavities	SRF, superconductivity, power-supply, radio-frequency	3249
	S. Wilde, B. Chesca Loughborough University, Loughborough, Leicestershire, United Kingdom A.N. Hannah, D.O. Malyshev, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G.B.G. Stenning STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The production of superconducting coatings for radio frequency cavities is a rapidly developing field that should ultimately lead to acceleration gradients greater than those obtained by bulk Nb RF cavities. Optimizing superconducting properties of Nb thin-films is therefore essential. Nb films were deposited by magnetron sputtering in pulsed DC mode onto Si (100) and MgO (100) substrates and also by high impulse magnetron sputtering (HiPIMS) onto Si (100), MgO (100) and polycrystalline Cu. The films were characterised using scanning electron microscopy, x-ray diffraction and DC SQUID magnetometry.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA059
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTY062	Multipactor Breakdown Modelling Using an Averaged Version of Furman's SEY Model	multipactoring, simulation, electron, cavity	3419
	S.A. Rice, J.P. Verboncoeur Michigan State University, East Lansing, Michigan, USA
	Funding: Work supported by a MSU Strategic Partnership Grant. Furman's seconday electron yield model is commonly used for the simulation of multipactor in accelerating cavities and other resonant structures. While accurate, the stochastic model requires many Monte Carlo simulations in order to characterize susceptibility to multipactor. This paper generalizes our previous research in characterizing a reduced-order Furman model, in which we replace the stochastic Furman model with a deterministic model based upon the Furman model's underlying statistics. Favorable comparisons between the full Furman model and the reduced-order Furman model are shown for multipactor simulations in a coaxial cavity, and the results are expected to generalize to other geometries.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY062
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWI033	Effects of Plasma Processing on Secondary Electron Yield of Niobium Samples	electron, cavity, gun, vacuum	3558
	M. Basovic, S. Popović, M. Tomovic, L. Vušković ODU, Norfolk, Virginia, USA F. Čučkov, A. Samolov University of Massachusetts Boston, Boston, Massachusetts, USA
	Impurities deposited on the surface of Nb during both the forming and welding of accelerator cavities add to the imperfections of the sheet metal, which then affects the overall performance of the cavities. This leads to a drop in the Q factor and limits the maximum acceleration gradient achievable per unit length of the cavities. The performance can be improved either by adjusting the fabrication and preparation parameters, or by mitigating the effects of fabrication and preparation techniques used. We have developed the experimental setup to determine Secondary Electron Yield (SEY) from the surface of Nb samples. Our aim is to show the effect of plasma processing on the SEY of Nb. The setup measures the secondary electron energy distribution at various incident angles as measured between the electron beam and the surface of the sample. The goal is to determine the SEY on non-treated and plasma treated surface of electron beam welded samples. Here we describe the experimental setup, plasma treatment device, and fabrication and processing of the Nb samples.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI033
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWI040	Experiment and Results on Plasma Etching of SRF Cavities	cavity, SRF, niobium, ion	3581
	J. Upadhyay, J.J. Peshl, S. Popović, L. Vušković ODU, Norfolk, Virginia, USA D.S. Im Old Dominion University, Norfolk, Virginia, USA H.L. Phillips, A-M. Valente-Feliciano JLab, Newport News, Virginia, USA
	The inner surfaces of SRF cavities are currently chemically treated (etched or electro polished) to achieve the state of the art RF performance. We designed an apparatus and developed a method for plasma etching of the inner surface for SRF cavities. The process parameters (pressure, power, gas concentration, diameter and shape of the inner electrode, temperature and positive dc bias at inner electrode) are optimized for cylindrical geometry. The etch rate non-uniformity has been overcome by simultaneous translation of the gas point-of-entry and the inner electrode during the processing. A single cell SRF cavity has been centrifugally barrel polished, chemically etched and RF tested to establish a baseline performance. This cavity is plasma etched and RF tested afterwards. The effect of plasma etching on the RF performance of this cavity will be presented and discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI040
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THSMS2	50th Anniversary: Accelerator Conferences in the U.S.	operation, linac, site, FEL	3668
	S.O. Schriber SOS, Eagle, Idaho, USA
	50th Anniversary: Accelerator Conferences in the U.S.
	Slides THSMS2 [1.063 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THSMS2
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF018	Simulation Studies of Plasma-based Charge Strippers	target, electron, ion, heavy-ion	3721
	O.S. Haas TEMF, TU Darmstadt, Darmstadt, Germany
	Calculations on the charge state distributions in different charge stripping media are presented. The main focus of this work is the width and peak efficiency of the final charge state distribution. For equal number densities fully-stripped plasma stripping media achieve much higher charge states than gas stripping media of the same nuclear charge. This is due to the reduced electron capture rates of free target electrons compared to bound target electrons. Furthermore, targets with low nuclear charge like hydrogen achieve higher charge states than targets with high nuclear charge like nitrogen in the case of both a plasma and a gas target. Equal final mean charge states can thus be achieved with lower density for plasmas and targets with low nuclear charge. The widths of the charge state distributions are very similar, slightly smaller for plasmas due to the different scaling of the dielectronic recombination rate. In comparison with calculations and measurements published in literature this work underestimates the width of targets with higher nuclear charge like, e.g., nitrogen gas. This is mainly due to the omission of multiple loss processes in the presented calculations. In the future we intend to expand the methods and models used in this work to improve the agreement with different measurements on charge state distributions in plasmas and gases.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF018
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF103	Current Status of the SANAEM RFQ Accelerator Beamline	rfq, proton, simulation, cavity	3952
	G. Turemen, B. Yasatekin Ankara University, Faculty of Sciences, Ankara, Turkey Y. Akgun, A.S. Bolukdemir TAEK, Ankara, Turkey A. Alacakir SNRTC, Ankara, Turkey A. Bozbey, A. Sahin TOBB ETU, Ankara, Turkey S. Erhan UCLA, Los Angeles, California, USA Ö. Mete UMAN, Manchester, United Kingdom S. Ogur, V. Yildiz Bogazici University, Bebek / Istanbul, Turkey S. Oz, A. Ozbey, H. Yildiz Istanbul University, Istanbul, Turkey G. Unel UCI, Irvine, California, USA F. Yaman IZTECH, Izmir, Turkey
	The design and production of the proton beamline of SPP, which aims to educate accelerator physicists and serve as particle accelerator technologies test bench, continues at TAEK-SANAEM as a multi-phase project. For the first phase, the 20 keV protons will be accelerated to 1.3 MeV by a single piece RFQ. Currently, the beam current and stability tests are ongoing for the Inductively Coupled Plasma ion source and the measured magnetic field maps of the Low Energy Beam Transport solenoids are being matched to the RFQ acceptance with various beam configurations of the ion source by using computer simulations. The production of the RFQ cavity was started by using high grade aluminum material which will be subsequently coated by Copper to reduce the RF losses. The installation of the low energy diagnostics box was also completed. On the RF side, the development of the hybrid power supply based on solid state and tetrode amplifiers continues. All RF transmission components are already produced with the exception of the circulator and the power coupling antenna which are in the manufacture and design phases, respectively. The acceptance tests of the produced RF components are ongoing. This work summarizes the design, production and test phases of the above mentioned SPP proton beamline components.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF103
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF104	Design of a Scaled High Duty Factor High Current Negative Penning Surface Plasma Source	cathode, ion, electron, simulation	3956
	D.C. Faircloth, S.R. Lawrie, T. Rutter, M. Whitehead, T. Wood STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom V.G. Dudnikov Muons, Inc, Illinois, USA
	The Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL) requires a 60 mA, 2 ms, 50 Hz H− beam. The present source can only deliver the current and pulse length requirements at 25 Hz. At 50 Hz there is too much droop in the beam current. To rectify this, a scaled source is being developed. This paper details the new source design and the experiments conducted that are guiding the design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF104
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF143	Saddle Antenna RF Ion Sources for Efficient Positive and Negative Ions Production	ion, extraction, operation, electron	4060
	V.G. Dudnikov, R.P. Johnson Muons, Inc, Illinois, USA G. Dudnikova UMD, College Park, Maryland, USA B. Han, S.N. Murray, T.R. Pennisi, C. Piller, M. Santana, M.P. Stockli, R.F. Welton ORNL, Oak Ridge, Tennessee, USA
	Funding: Work supported in part by US DOE Contract DE-AC05-00OR22725 and by STTR grant DE-SC0011323. Existing RF Surface Plasma Sources (SPS) for accelerators have specific efficiencies for H⁺ and H⁻ ion generation ~3-5 mA/cm² kW, where about 50 kW of RF power is typically needed for 50 mA beam current production. The Saddle Antenna (SA) SPS described here was developed to improve H⁻ ion production efficiency, reliability and availability. In SA RF ion source the efficiency of positive ion generation in the plasma has been improved to 200 mA/cm² kW. After cesiation, the current of negative ions to the collector was increased from 1 mA to 10 mA with RF power ~1.5 kW in the plasma (6 mm diameter emission aperture) and up to 30 mA with ~4 kW RF. Continuous wave (CW) operation of the SA SPS has been tested on the test stand. The general design of the CW SA SPS is based on the pulsed version. Some modifications were made to improve the cooling and cesiation stability. CW operation with negative ion extraction was tested with RF power up to 1.8 kW from the generator (~1.2 kW in the plasma) with production up to Ic=7 mA. Long term operation was tested with 1.2 kW from the RF generator (~0.8 kW in the plasma) with production of Ic=5 mA, Iex ~15 mA (Uex=8 kV, Uc=14 kV).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF143
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOAC1

Awake: the Proof-of-principle R&D Experiment at CERN

proton, laser, electron, experiment

34

P. Muggli
MPI, Muenchen, Germany
M. Bernardini, T. Bohl, C. Bracco, A.C. Butterworth, S. Cipiccia, H. Damerau, S. Döbert, V. Fedosseev, E. Feldbaumer, E. Gschwendtner, W. Höfle, A. Pardons, A.V. Petrenko, J.S. Schmidt, M. Turner, H. Vincke
CERN, Geneva, Switzerland

The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) is a proof-of-principle R&D experiment at CERN. It is the world’s first proton driven plasma wakefield acceleration experiment, using a high-energy proton bunch to drive a plasma wakefield for electron beam acceleration. The AWAKE experiment will be installed in the former CNGS facility and uses the 400 GeV proton beam bunches from the SPS, which will be sent to a plasma source. An electron beam will be injected into the plasma cell to probe the accelerating wakefield. Challenging modifications in the area and new installations are required for AWAKE. First proton beam to the experiment is expected late 2016. The accelerating electron physics will start late 2017. This paper gives an overview of the project from a physics and engineering point of view, it describes the main activities, the milestones, the organizational set-up for the project management and coordination.

Slides MOAC1 [21.632 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOAC1

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWA003

Optimal Generalized Finite Difference Solution to the Particle-in-Cell Problem

framework, simulation, space-charge, factory

77

X. Wang, X. Jiao, H. Liu, V. Samulyak, K. Yu
SBU, Stony Brook, USA
V. Samulyak
BNL, Upton, Long Island, New York, USA

The particle-in-cell (PIC) method is widely used in applications, such as in electromagnetics, but the accuracy of its solutions degrades when the particle distribution is highly non-uniform. In our work, we propose an adaptive PIC method with optimal point distribution and a generalized finite difference (GFD) scheme. Our method replaces the Cartesian grid in the classical PIC with adaptive computational nodes or particles, to which the charges from the sample particles are assigned by a weighted least-square approximations. The partial differential equation is then discretized using a GFD method and solved with fast linear solvers. The density of computational particles is chosen adaptively, so that the error from GFD and that from Monte Carlo integration are balanced and the total error is approximately minimized. We also present the verification results using electrostatic problems and comparison of accuracy and solution time of our method with the classical PIC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA003

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWA042

Sub-fs Electron Bunch Generation Using Magnetic Compressor at SINBAD

electron, simulation, acceleration, laser

207

J. Zhu, R.W. Aßmann, U. Dorda, J. Grebenyuk, B. Marchetti
DESY, Hamburg, Germany

In order to achieve high quality electron beams by laser-driven plasma acceleration with external injection, sub-fs bunches with a few fs arrival-time jitter are required. SINBAD (Short Innovative Bunches and Accelerators at DESY) is a proposed dedicated accelerator research and development facility at DESY. One of the baseline experiment at SINBAD is ARES (Accelerator Research Experiment at SINBAD), which will provide ultra-short electron bunches of 100 MeV to one or two connected beam lines. We present start-to-end simulation studies of sub-fs bunches generation at ARES using a magnetic compressor with a slit. In addition, the design of a dogleg with tunable R56 for the second beamline is also presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA042

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWA048

Transverse Emittance Measurement for Low Energy Ion Beams Using Quadrupole Scan Method

ion, emittance, ion-source, ECR

226

S. Kumar, A. Mandal
IUAC, New Delhi, India

Low energy ion beam facility (LEIBF) * at IUAC consists of all permanent magnet 10 Ghz electron cyclotron resonance (ECR) ion source (NANOGUN) ** along with 400 kV high voltage accelerating platform, a switching cum analysing magnet and electrostatic quadrupoles. Higher beam currents of heavy charge states and low energy of ion beams puts tremendous challenge to transport the ion beam from source to target. The normalized emittance of analysed ion beam is measured for specific charge to mass ratio using electrostatic quadrupole scan method *** for various source parameters like RF power and injection pressure of gas etc. For various m/q ratios, the normalized transverse emittance ranges from 0.1 to 0.6 mm-mrad. It is attributed to beam rotation induced by ECR axial magnetic field, effect of ion temperature in plasma, non linear electric fields and space charge etc which play a significant role in emittance growth.
* A. Mandal et. al. Proceedings of IPAC2011, WEPC011, San Sebastián, Spain
** D Kanjilal et. al. Indian J. Pure Appl. Phys. 39 (2001) 25
*** I. G. Brown:The physics and technology of ion sources

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA048

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE022

Physical Model of Partial RF Discharge in Isochronous Cyclotrons

electron, cyclotron, ion, ion-source

323

V.S. Dyubkov
MEPhI, Moscow, Russia
S. Korenev
Siemens Medical Solutions Molecular Imaging, Knoxville, TN, USA

The physical model for the partial RF discharge - based on the ionization of molecules of residual gas by electron detachment as a result of the electro-dissociation of negative hydrogen ions in isochronous cyclotrons - is proposed in this paper. The result of the simulation of the ionization of gas molecules by these electrons using RF voltage inside the Eclipse cyclotron (kinetic energy of 11 MeV) is presented. The analysis of the conductivity of the RF plasma (partial RF discharge) is given. The influence of the magnetic field on the properties of the partial RF discharge is discussed. The application of this model is for isochronous cyclotrons with low kinetic energy (10^-15 MeV).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE023

3D Computer Simulations of the Ultrarelativistic Beam Dynamics in Super Colliders

simulation, collider, focusing, experiment

326

M.A. Boronina, V.A. Vshivkov
ICM&MG SB RAS, Novosibirsk, Russia
G. Dudnikova
ICT SB RAS, Novosibirsk, Russia

Funding: The work is supported by RFBR Grants 14-01-31088, 14-01-00392, 14-07-00241.
The problem of numerical modeling of beam-beam interaction with high relativistic factor (~10⁴) is considered. We present 3D a self-consistent simulation model based on particle-in-cell method. The mixed Euler-Lagrangian decomposition is used in parallel algorithm for achieving good load balancing and reducing communication cost. Stable regimes of beam dynamics, depending on the beams configuration (beta-function, emittance, energy, currents and relative offset) can be found on the base of the model. In the calculations we used 10⁸ particles on the grid 100x100x100, the number of processors depends highly on the beam shape. The Lomonosov Super Computer and Siberian Supercomputer Centre cluster were used to perform the presented simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE023

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPJE084

Particle-in-cell Simulations of a Plasma Lens at Daresbury Laboratory

focusing, emittance, simulation, experiment

518

K. Hanahoe, O. Mete, G.X. Xia
UMAN, Manchester, United Kingdom
D. Angal-Kalinin, J.K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J.D.A. Smith
TXUK, Warrington, United Kingdom

Feasibility of a focusing element using the transverse fields provided by a plasma cell was studied numerically. In this paper, an experimental set up is proposed for various beam parameters available from the VELA and CLARA beam lines at Daresbury Laboratory. 2D simulation results from VSim, and expected results from planned measurement stations are presented. Field properties and the advantages and disadvantages of such an instrument compared to conventional focusing elements are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE084

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA024

A Parallel Particle-Particle, Particle-Mesh Solver for Studying Coulomb Collisions in the Code IMPACT-T

emittance, electron, simulation, space-charge

593

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

Funding: This work is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
In intense charged-particle beams, the presence of Coulomb collisions can result in growth of the beam slice energy spread and emittance that cannot be captured correctly using traditional particle-in-cell codes. Particle-particle, particle-mesh solvers take a hybrid approach, combining features of N-body and particle-in-cell solvers, to correctly capture the effect of short-range particle interactions with less computing time than direct N-body solvers. We describe the implementation and benchmarking of such a solver in the code IMPACT-T for beam dynamics applications.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA024

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA030

Multisymplectic Integrators for Accelerator Tracking Codes

space-charge, simulation, storage-ring, DTL

614

S.D. Webb, D.L. Bruhwiler
RadiaSoft LLC, Boulder, Colorado, USA

It has been long understood that long time single particle tracking requires symplectic integrators to keep the simulations stable. In contrast, space charge has been added to tracking codes without much regard for this. Indeed, multisymplectic integrators are a promising new field which may lead to more stable and accurate simulations of intense beams. We present here the basic concept, through a spectral electrostatic field solve which is suitable for adapting into existing tracking codes. We also discuss the limitations of current algorithms, and suggest directions for future development for the next generations of high intensity accelerators.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA030

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA037

Electron Cloud Buildup and Dissipation Models For PIP-II

electron, simulation, proton, space-charge

626

S.A. Veitzer, P. Stoltz
Tech-X, Boulder, Colorado, USA

Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499), and the SCiDAC-3 project (DE-SC0008920).
Buildup of electron plasmas in accelerator cavities can cause beam degradation and limit performance in high-intensity circular particle accelerators. This is especially important in machines such as the LHC, and PIP-II, where mitigation techniques such as beam scrubbing in order to decrease the SEY are expensive and time consuming. Modeling of electron cloud buildup and dissipation can provide understanding as to the potential negative effects of electron clouds on beam properties, as well as estimates of the mitigation required to maintain accelerator performance and beam quality as accelerators move to higher intensity configurations. We report here on simulations of electron cloud buildup and dissipation for geometry, beam and magnetic field configurations describing the Recycler at Fermilab. We perform electrostatic simulations in 3D with VSim PIC, including the effects of space charge and secondary electrons. We quantify the expected survival rate of electrons in these conditions, and argue that improvements in reducing the SEY is unlikely to mitigate the electron cloud effects.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA037

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA044

Barrier Shock Compression with Longitudinal Space Charge

space-charge, simulation, emittance, electron

646

B. Beaudoin, I. Haber, R.A. Kishek
UMD, College Park, Maryland, USA

Funding: This work is supported by the US Dept. of Energy, Office of High Energy Physics.
Synchrotrons and storage rings routinely employ RF barrier buckets as a means of accumulating charge to increase the peak intensity and preserve longitudinal emittance while minimizing emittance growth [1-3]. This was shown in the main injector and recycler at Fermilab as well as the SIS-18 at GSI Helmholtz center for heavy ion research. The RF cavities typically used are ferrite loaded magnetic alloys with low Q to maximize bandwidth and generate single pulses, either as delta functions, triangular or half/full period sine waves. The University of Maryland Electron Ring (UMER) group is studying a novel scheme of bunch compression in the presence of longitudinal space charge. It has been analytically shown through 1-D computations that the presence of space-charge considerably improves the efficiency of the barrier compression by taking advantage of the shock-front that launches when the barrier moves into a space-charge dominated beam. In this paper, we summarize the initial results of the study.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA044

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMA059

Lorentz boosted frame simulation of Laser wakefield acceleration using hybrid Yee-fft solver in quasi-3d geometry

simulation, laser, wakefield, acceleration

691

P. Yu, A.W. Davidson, V.K. Decyk, W.B. Mori, A. Tableman, F.S. Tsung
UCLA, Los Angeles, California, USA
F. Fiuza, L.O. Silva, J. Vieira
IPFN, Lisbon, Portugal
R.A. Fonseca
ISCTE - IUL, Lisboa, Portugal
W. Lu, X.L. Xu
TUB, Beijing, People's Republic of China

We present results from a preliminary study on modeling Laser wakefield acceleration (LWFA) with OSIRIS in a Lorentz boosted frame using a quasi-3D algorithm. In the quasi-3D algorithm, the fields and currents are expanded into azimuthal harmonics and only a limited number of harmonics are kept. Field equations in (r,z) space are solved for a desired number of harmonics in φ. To suppress the numerical Cerenkov instability (NCI) that inevitably arises due to the relativistic plasma drift in the simulation, we use a hybrid Yee-FFT solver in which the field equations are solved in (k_z, r) space, where \hat{z} is the drifting direction. Preliminary results show that high fidelity LWFA boosted frame simulations can be carried out with no evidence of the NCI. Good agreement is found when comparing LWFA boosted frame simulations in the full 3D geometry against those in the quasi-3D geometry. In addition, we discuss how the moving window can be combined with the hybrid Yee-FFT solver to further speed up the simulation. The results indicate that unprecedented speed ups for LWFA simulations can be achieved when combining the Lorentz boosted frame technique, the quasi-3D algorithm, and a moving window.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA059

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMN012

SPACE Code for Beam-Plasma Interaction

simulation, ion, electron, electromagnetic-fields

728

K. Yu, V. Samulyak
SBU, Stony Brook, USA
V. Samulyak
BNL, Upton, Long Island, New York, USA

A parallel particle-in-cell code SPACE has been developed for the simulation of electromagnetic fields, relativistic particle beams, and plasmas. The algorithms include atomic processes in the plasma, proper boundary conditions, an efficient method for highly-relativistic beams in non-relativistic plasma, support for simulations in relativistic moving frames, and special data transfer algorithm from the moving to the laboratory frame that collects particles and fields in the lab frame without time shift due to the Lorentz transform, enabling data analysis and visualization. Plasma chemistry algorithms implement atomic physics processes such as the generation and evolution of plasma, recombination of plasma, and electron attachment on dopants in dense neutral gas. Benchmarks and experimental validation tests are also discussed. The code has been used for the simulation of processes relevant to the eRHIC program at BNL and the high pressure RF cavity (HPRF) program at Fermilab.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMN013

Simulation of Beam-Induced Plasma in Gas Filled Cavities

ion, simulation, cavity, electron

731

K. Yu, V. Samulyak
SBU, Stony Brook, USA
M. Chung
UNIST, Ulsan, Republic of Korea
B.T. Freemire
IIT, Chicago, Illinois, USA
V. Samulyak
BNL, Upton, Long Island, New York, USA
A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, Illinois, USA

Understanding of the interaction of muon beams with plasma in muon cooling devices is important for the optimization of the muon cooling process. SPACE, a 3D electromagnetic particle-in-cell (EM-PIC) code, is used for the simulation support of the experimental program on the hydrogen gas filled RF cavity in the Mucool Test Area (MTA) at Fermilab. We have investigated the plasma dynamics in the RF cavity including the process of power dump by plasma (plasma loading), recombination of plasma, and plasma interaction with dopant material. By comparison with experiments in the MTA, simulations suggest several unknown properties of plasma such as the effective recombination rate, the electron attachment time on dopant molecule, and the ion - ion recombination rate in the plasma.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN013

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMN015

Simulation of Beam-Induced Plasma for the Mitigation of Beam-Beam Effects

proton, simulation, electron, beam-beam-effects

734

J. Ma, V. Samulyak, K. Yu
SBU, Stony Brook, New York, USA
V. Litvinenko, V. Samulyak, G. Wang
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
V. Samulyak
SUNY SB, Stony Brook, New York, USA

One of the main challenges in the increase of luminosity of circular colliders is the control of the beam-beam effect. In the process of exploring beam-beam mitigation methods using plasma, we evaluated the possibility of plasma generation via ionization of neutral gas by proton beams, and performed highly resolved simulations of the beam-plasma interaction using SPACE, a 3D electromagnetic particle-in-cell code. The process of plasma generation is modelled using experimentally measured cross-section coefficients and a plasma recombination model that takes into account the presence of neutral gas and beam-induced electromagnetic fields. Numerically simulated plasma oscillations are consistent with theoretical analysis. In the beam-plasma interaction process, high-density neutral gas reduces the mean free path of plasma electrons and their acceleration. A numerical model for the drift speed as a limit of plasma electron velocity was developed. Simulations demonstrate a significant reduction of the beam electric field in the presence of plasma. Preliminary simulations using fully-ionized plasma have also been performed and compared with the case of beam-induced plasma.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN015

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPHA026

Present and Future Optical-to-Microwave Synchronization Systems at REGAE Facility for Electron Diffraction and Plasma Acceleration Experiments

laser, electron, detector, timing

833

M. Titberidze, F.J. Grüner, A.R. Maier, B. Zeitler
CFEL, Hamburg, Germany
S.W. Epp
MPSD, Hamburg, Germany
M. Felber, K. Flöttmann, T. Lamb, U. Mavrič, J.M. Müller, H. Schlarb, C. Sydlo
DESY, Hamburg, Germany
F.J. Grüner, A.R. Maier, M. Titberidze
Uni HH, Hamburg, Germany
E. Janas
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

Relativistic Electron Gun for Atomic Explorations (REGAE) is a Radio Frequency (RF) driven linear accelerator. It uses frequency tripled short photon pulses (~ 35 fs) from the Titanium Sapphire (Ti:Sa.) Laser system in order to generate electron bunches from the photo-cathode. The electron bunches are accelerated up to ~ 5 MeV kinetic energy and compressed down to sub-10 fs using the so called ballistic bunching technique. REGAE currently is used for electron diffraction experiments (by Prof. R.J.D. Miller's Group). In near future within the collaboration of Laboratory for Laser- and beam-driven plasma Acceleration (LAOLA), REGAE will also be employed to externally inject electron bunches into laser driven linear plasma waves. Both experiments require very precise synchronization (sub-50 fs) of the photo-injector laser and RF reference. In this paper we present experimental results of the current and new optical to microwave synchronization systems in comparison. We also address some of the issues related to the current system and give an upper limit in terms of its long-term performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA026

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI015

A Low Time-Dispersion Refractive Optical Transmission Line for Streak Camera Measurements

electron, experiment, database, resonance

1178

J.G. Power, G. Ha
ANL, Argonne, Illinois, USA
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea

Funding: Work supported by the U.S. Department of Energy office of High Energy Physics.
Streak camera measurements of the charge particle bunch length are limited in resolution due to several factors: (1) the light from the source (optical transition radiation, Cherenkov, synchrotron radiation, etc.); (2) time dispersion introduced in the optical transmission line between the source and the streak camera; and finally (3) the streak camera resolution. The limiting resolution usually arises from the optical transmission line. While an all-reflective transmission line can eliminate dispersion, the system is complicated and expensive. In this paper, we consider how to design a refractive optical transport line to minimize the time dispersion while maximizing the signal. We present a theoretical model of the dispersion, modeling, and measurements of the time dispersion for several different lens materials.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI015

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI018

New Hadron Monitor By Using A Gas-Filled RF Resonator

electron, hadron, proton, radiation

1189

K. Yonehara, A.V. Tollestrup, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
G. Fasce
CNI, Roma, Italy
G. Flanagan, R.P. Johnson
Muons, Inc, Illinois, USA

It is trend to build an intense neutrino beam facility for the fundamental physics research, e.g. LBNF at Fermilab, T2K at KEK, and CNGS at CERN. They have investigated a hadron monitor to diagnose the primary/secondary beam quality. The existing hadron monitor based on an ionization chamber is not robust in the high-radiation environment vicinity of MW-class secondary particle production targets. We propose a gas-filled RF resonator to use as the hadron monitor since it is simple and hence radiation robust in this environment. When charged particles pass through the resonator they produce ionized plasma via the Coulomb interaction with the inert gas. The beam-induced plasma changes the permittivity of inert gas. As a result, a resonant frequency in the resonator shifts with the amount of ionized electrons. The radiation sensitivity is adjustable by the inert gas pressure and the RF amplitude. The hadron profile will be reconstructed with a tomography technique in the hodoscope which consists of X, Y, and theta layers by using a strip-shaped gas resonator. The sensitivity and possible system design will be shown in this presentation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI018

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPWI052

Responsivity Study of Diamond X-ray Monitors with nUNCD Contact

photon, synchrotron, detector, database

1273

M. Gaowei, J. Smedley
BNL, Upton, Long Island, New York, USA
E.M. Muller, T. Zhou
SBU, Stony Brook, New York, USA
A.V. Sumant
Argonne National Laboratory, Center for Nanoscale Materials, Argonne, USA

Nitrogen doped ultrananocrystalline diamond (nUNCD) grown on the surface of a CVD single crystal diamond is tested at various beamlines covering an x-ray photon energy range of 200eV to 28 keV. The nUNCD has much lower x-ray absorption than metal contacts and is designed to improve the performance of our device. The responsivity of nUNCD diamond x-ray detector is compared with the conventional platinum coated diamond x-ray beam position monitor and the results are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI052

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUYC2

Multi-GeV Plasma Acceleration Results at BELLA

laser, electron, experiment, injection

1319

A.J. Gonsalves, C. Benedetti, S.S. Bulanov, J. Daniels, E. Esarey, C.G.R. Geddes, H.S. Mao, D.E. Mittelberger, K. Nakamura, C.B. Schroeder, C. Tóth, J. van Tilborg
LBNL, Berkeley, California, USA
W. Leemans
UCB, Berkeley, California, USA

Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231
Laser-plasma accelerators (LPAs)* are being investigated as a compact driver for light sources and high-energy linear colliders. Recently 2 GeV beams were generated by focusing ≈ 100 J laser pulses onto a gas target**. We report here on the generation of beams with energy up to 4.2 GeV using 16 J of laser pulse energy at the BErkeley Lab Laser Accelerator (BELLA)***. This was achieved by using laser pulses of high spatial and temporal quality coupled to a pre-formed capillary discharge waveguide of length 9 cm. The waveguide (in conjunction with self-guiding) allowed for mitigation of diffraction. High spatial quality (Strehl ratio at focus 0.8±0.1) was achieved using a deformable mirror placed before the focusing optic. The dominant contribution to the non-Gaussian content of the focal spot was the near-field intensity profile. For maximum efficiency high-power femtosecond systems employ super-Gaussian near-field profiles of the form I(r)∝e^-2(r/w^N), where I is the intensity, r is the radial coordinate, w is the spot size, and N is the order. Compared with Gaussian laser pulses where N=2, pulses from the BELLA laser system had N=10. Simulations showed that an increased contribution of self-guiding was required to effectively confine the laser energy for optimum acceleration and mitigation of damage to the capillary waveguide. Through appropriate choice of plasma density electron beams with energy up to 4.2 GeV were observed. In this regime the electron beam angular fluctuations were > 2 mrad rms, caused in part by errors in waveguide alignment and by laser-induced damage to the capillary that introduces plasma asymmetry. Improved alignment of the waveguide and mitigation of capillary damage allowed for reduction in angular fluctuations to 0.6 mrad rms. The electron beams had energy of 2.7±0.1 GeV, charge of 150 pC, and divergence less than 1 mrad.
* E. Esarey, et al., Rev. Mod. Phys. 81, 1229 (2009)
** X. Wang, et al., Nat. Communications 4, 1988 (2013)
*** W. P. Leemans, et al., Phys. Rev. Lett. 113, 245002 (2014)

Slides TUYC2 [13.023 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUYC2

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUBB1

Charge Stripper Development for FRIB

ion, heavy-ion, proton, linac

1339

F. Marti, P. Guetschow, J.A. Nolen
FRIB, East Lansing, Michigan, USA
A. Hershcovitch, P. Thieberger
BNL, Upton, Long Island, New York, USA
Y. Momozaki, J.A. Nolen, C.B. Reed
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and NSF grant PHY-1102511
The Facility for Rare Isotope Beams (FRIB) at Michigan State University is building a heavy ion linac to produce rare isotopes by the fragmentation method. The linac will accelerate ions up to U to energies above 200 MeV/u with beam powers up to 400 kW. At energies between 16 and 20 MeV/u the ions will be stripped to higher charge states to increase the energy gain downstream in the linac. The main challenges in the stripper design are due to the high power deposited by the ions in the stripping media (~ 30 MW/cm³) and radiation damage if solids are used. For that reason self-recovering stripper media must be used. The baseline stripper choice is a high-velocity, thin film of liquid lithium with an alternative option of a helium gas stripper. We present in this paper the status of the R&D and construction of the final stripper. Extensive experimental work has been performed on both options.

Slides TUBB1 [3.534 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUBB1

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA030

Compression of an Electron-bunch by Means of Velocity Bunching at ARES

bunching, electron, emittance, simulation

1472

B. Marchetti, R.W. Aßmann, U. Dorda, J. Grebenyuk, J. Zhu
DESY, Hamburg, Germany

ARES is a planned linear accelerator for research and development in the field of production of ultra-short electron bunches. The goal of ARES is to produce low charge (0.2-50pC), ultra-short (from few fs to sub-fs) bunches, with improved arrival time stability (less than 10fs) for various applications, such as external injection for Laser Plasma Wake-Field acceleration. The ARES layout will allow to perform and compare different kind of conventional e-bunch compression techniques, such as pure velocity bunching*, hybrid velocity bunching (i.e. velocity bunching plus magnetic compression) and pure magnetic compression with the slit insertion**. This flexibility will allow to directly compare the different methods in terms of arrival time stability and local peak current. In this paper we present simulation results for the compression of an electron bunch with 0.5 pC charge. We compare the case of pure velocity bunching compression to the one of a hybrid compression using velocity bunching plus a magnetic compressor.
* M. Ferrario et al., Phys. Rev. Lett. 104, 054801 (2010).
** P. Emma et al., PRL 92 7 (2004).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA030

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA031

Compression of Train of Bunches with Ramped Intensity Profile at SPARC_LAB

linac, laser, cathode, electron

1476

B. Marchetti
DESY, Hamburg, Germany
A. Bacci
Istituto Nazionale di Fisica Nucleare, Milano, Italy
E. Chiadroni, M. Ferrario, R. Pompili
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy

The production and acceleration of train of bunches with variable spacing in the ps/sub-ps range having ramped intensity profile are interesting to drive a plasma wave in the so-called resonant Plasma Wake-Fields Acceleration (r-PWFA)*. At SPARC_LAB trains having a constant intensity profile have been produced for the first time by using a shaped photo-cathode laser combined with the use of the velocity bunching compression technique**,***,****. If the sub-bunches have ramped intensity, i.e. they have different charge density, the space charge force affects differently the development of the longitudinal phase space of each one of them during the compression. In this paper we present preliminary simulations for the compression of a ramped train of bunches. The differences between the beam dynamics for a train of bunches having constant intensity profile and the ramped train are underlined. We discuss also the possibility of properly tuning the shaping of the photocathode laser to balance the space charge effect.
* SLAC-PUB-3528
** M. Ferrario et al., Phys. Rev. Lett. 104, 054801 (2010).
*** M. Ferrario et al. NIM A 637, S43-S46 (2011).
**** E. Chiadroni et al., Rev. Sci. Instrum. 84, 022703

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA031

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWA046

Facility Upgrade at PITZ and First Operation Results

gun, laser, operation, electron

1518

A. Oppelt, P. Boonpornprasert, A. Donat, J.D. Good, M. Groß, H. Huck, I.I. Isaev, L. Jachmann, D.K. Kalantaryan, M. Khojoyan, W. Köhler, G. Koss, G. Kourkafas, M. Krasilnikov, O. Lishilin, D. Malyutin, J. Meissner, D. Melkumyan, M. Otevřel, M. Penno, B. Petrosyan, S. Philipp, M. Pohl, Y. Renier, T. Rublack, B. Schöneich, J. Schultze, F. Stephan, F. Tonisch, G. Trowitzsch, G. Vashchenko, R.W. Wenndorff
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
M. A. Bakr
Assiut University, Assiut, Egypt
C. Hernandez-Garcia
JLab, Newport News, Virginia, USA
G. Pathak
Uni HH, Hamburg, Germany
D. Richter
HZB, Berlin, Germany

The Photo Injector Test facility at DESY, Zeuthen site (PITZ), develops, optimizes and characterizes high brightness electron sources for free electron lasers like FLASH and the European XFEL. In the last year, the facility was significantly upgraded by the installation of a new normal conducting radio- frequency (RF) gun cavity with its new waveguide system for the RF feed, which should allow stable and reliable gun operation, as required for the European XFEL. Other relevant additions include beamline modifications for improving the electron beam transport through the PITZ accelerator, extending the beam-based measurement capabilities, and preparing the installation of a plasma cell. Furthermore, the laser hutch was re-arranged in order to be able to house an additional, new photo cathode drive laser system which should be able to produce 3D ellipsoidal laser pulses to further improve the electron beam quality. This paper describes in detail the aforementioned facility upgrades and reports on the first operation experience with the new gun setup.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA046

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTY074

Muon Beam Emittance Evolution in the Helical Ionization Cooling Channel for Bright Muon Sources

emittance, collider, space-charge, simulation

2203

K. Yonehara, C.Y. Yoshikawa
Fermilab, Batavia, Illinois, USA
C.M. Ankenbrandt, R.P. Johnson, S.A. Kahn
Muons, Inc, Illinois, USA
M. Chung
UNIST, Ulsan, Republic of Korea
Y.S. Derbenev, A.V. Sy
JLab, Newport News, Virginia, USA
B.T. Freemire
IIT, Chicago, Illinois, USA

The six-dimensional ionization cooling is essential to design a bright muon source. A geometry constraint is a challenge issue in a compact helical cooling channel (HCC). Especially, the HCC requires a large bore helical magnet and a compact helical RF system to incorporate the RF into the magnet chamber. A new emittance evolution has been designed to mitigate the geometry constraint. The HCC was functionally separated into three parts sections. The lattice at the initial section provides a large transverse acceptance by using a strong helical focus magnet. Once the transverse beam size is small enough to get into the compact RF the HCC lattice in the middle section generates a large longitudinal beta tune to dominate the longitudinal cooling. Consequently, the longitudinal emittance becomes smaller than the transverse one at the end of middle section. In the final section, the magnetic field strength is gradually reduced to match out the helical channel to the straight solenoid. As a result, the emittance exchange takes place and the final transverse emittance becomes smaller than the longitudinal one. The new emittance evolution scenario will be discussed in this presentation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY074

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPWI059

Influence of Plasma Loading in a Hybrid Muon Cooling Channel

ion, electron, cavity, emittance

2381

D. Stratakis
BNL, Upton, Long Island, New York, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
K. Yonehara
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In a hybrid 6D cooling channel, cooling is accomplished by reducing the beam momentum through ionization energy loss in wedge absorbers and replenishing the momentum loss in the longitudinal direction with gas-filled rf cavities. While the gas acts as a buffer to prevent rf breakdown, gas ionization may also occur as the beam passes through a HPRF cavity. The resulting plasma, may gain substantial energy from the rf electric field which it can transfer via collisions to the gas, an effect known as plasma loading. In this paper, we investigate the influence of plasma loading on the cooling performance of a rectilinear hybrid channel. With the aid of numerical simulations we examine the sensitivity in cooling performance and plasma loading to key parameters such as the rf gradient and gas pressure.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI059

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA003

Simulations of Electron-Proton Beam Interaction before Plasma in the AWAKE Experiment

proton, electron, wakefield, quadrupole

2492

U. Dorda, R.W. Aßmann, J. Grebenyuk
DESY, Hamburg, Germany
C. Bracco, A.V. Petrenko, J.S. Schmidt
CERN, Geneva, Switzerland

The on-axis injection of electron bunches in the proton-driven plasma wake at the AWAKE experiment at CERN implies co-propagation of a low-energy electron beam with the long high-energy proton beam in a common beam pipe over several meters upstream of the plasma chamber. The possible effects of the proton-induced wakefields on the electron bunch phase space in the common beam pipe region may have crucial implications for subsequent electron trapping and acceleration in plasma. We present the CST Studio simulations of the tentative common beam pipe setup and the two beam co-propagating in it. Simulated effects of the proton wakefields on electrons are analysed and compared to analytical predictions.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA003

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA005

Simulations Study for Self-Modulation Experiment at PITZ

electron, wakefield, simulation, experiment

2496

G. Pathak, F.J. Grüner
Uni HH, Hamburg, Germany
C. Benedetti, C.B. Schroeder
LBNL, Berkeley, California, USA
M. Groß, F. Stephan
DESY Zeuthen, Zeuthen, Germany
A. Martinez de la Ossa, T.J. Mehrling, J. Osterhoff
DESY, Hamburg, Germany

Self-modulation (SM) of proton beams in plasma has recently gained interest in context with the ongoing PWFA experiment of the AWAKE collaboration at CERN. Instrumental for that experiment is the SM of a proton beam to generate bunchlets for resonant wave excitation and efficient acceleration. A fundamental understanding of the underlying physics is vital, and hence an independent experiment has been set up at the beamline of the Photo Injector Test Facility at DESY, Zeuthen Site (PITZ), to study the SM of electron beams in a plasma. This contribution presents simulation results on SM experiments at PITZ using the particle-in-cell code HiPACE. The simulation study is crucial to optimize the beam and plasma parameters for the experiment. Of particular interest is the energy modulation imprinted onto the beam by means of the generated wakefields in the plasma. With the support of simulations the observation of this information in the experiment can be used to deduce key properties of the accelerating electric fields such as their magnitude and their phase velocity, both of significant importance for the design of self-modulated plasma-based acceleration experiments.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA005

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA006

Laser Propagation Effects During Photoionization of Meter Scale Rubidium Vapor Source

laser, experiment, proton, wakefield

2499

J.T. Moody, F. Batsch, A. Joulaei, P. Muggli, E. Öz
MPI-P, München, Germany
N. Berti, J. Kasparian
University of Geneva, GAP Biophotonics, Carouge, Switzerland

The baseline AWAKE experiment requires a 10 meter long plasma source with a density of 10¹⁵ cm􀀀^-3 and a density uniformity of 0.2%. To produce this plasma, a temperature stabilized rubidium vapor source is photoionized by a terawatt peak power laser pulse. In this paper we describe the laser pulse evolution within the plasma source including the dispersive, diffractive, and photoionization effects on the laser pulse. These calculations will be experimentally investigated in a meter long heat pipe oven using scaled laser parameters.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA007

The AWAKE Proton-driven Plasma Wakefield Experiment at CERN

electron, wakefield, injection, experiment

2502

P. Muggli
MPI-P, München, Germany

Funding: For the AWAKE collaboration
The AWAKE experiment at CERN * aims at studying plasma wakefield generation and acceleration driven by proton bunches. The first experiments will focus on the self-modulation instability of the long (~12cm, rms) proton bunch in the plasma. This instability is used to transform the incoming bunch into a train of short bunches with a period approximately equal to the plasma wavelength, ~1.2mm at a nominal plasma electron density of 7·10¹⁴/cc. These experiments are planned for the end of 2016. Later, low energy (~15MeV) electrons will be externally injected to sample the wakefields and be accelerated beyond 1GeV. The main goals of the experiment will be summarized and the progress with the plasma source, beam diagnostics and injection method will be presented.
* AWAKE Collaboration, Plasma Phys. Control. Fusion 56 084013 (2014)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA007

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA008

Measuring the Self-modulation Instability of Electron and Positron Bunches in Plasmas

electron, cavity, radiation, positron

2506

P. Muggli, O. Reimann
MPI-P, München, Germany
E. Adli, V.K.B. Olsen
University of Oslo, Oslo, Norway
J. Allen, S.J. Gessner, S.Z. Green, M.J. Hogan, M.D. Litos, B.D. O'Shea, V. Yakimenko
SLAC, Menlo Park, California, USA
L.D. Amorim
IST, Lisboa, Portugal
G. Andonian, C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi, O. Williams
UCLA, Los Angeles, California, USA
N.C. Lopes, L.O. Silva, J. Vieira
Instituto Superior Tecnico, Lisbon, Portugal

The self-modulation instability (SMI) * can be used to transform a long, charged particle bunch into a train of periodically spaced shorter bunches. The SMI occurs in a plasma when the plasma wake period is much shorter than the bunch length. The train of short bunches can then resonantly drive wakefields to much larger amplitude that the long bunch can. The SMI will be used in the AWAKE experiment at CERN, where the wakefields will be driven by a high-energy (400GeV) proton bunch. ** However, most of the SMI physics can be tested with the electron and positron bunches available at SLAC-FACET. *** In this case, the bunch is ~10 plasma wavelengths long, but can drive wakefields in the GV/m range. FACET has a meter-long plasma **** and is well equipped in terms of diagnostic for SMI detection: optical transition radiation for transverse bunch profile measurements, coherent transition radiation interferometry for radial modulation period measurements and energy spectrometer for energy loss and gain measurement of the drive bunch particles. The latest experimental results will be presented.
* N. Kumar et al., PRL 104, 255003 (2010)
** AWAKE Collaboration, PPCF 56 084013 (2014)
*** J. Vieira et al., PoP 19, 063105 (2012)
**** S.Z. Green et al., PPCF 56, 084011 (2014)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA008

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA010

A High Intensity Proton Source for the European Spallation Source Facility

proton, emittance, extraction, site

2509

L. Celona, L. Allegra, L. Andò, A.C. Caruso, G. Castro, F. Chines, G. Gallo, S. Gammino, A. Longhitano, S. Marletta, D. Mascali, L. Neri, S. Passarello, G. Torrisi
INFN/LNS, Catania, Italy
A. Longhitano
ALTEK, San Gregorio (CATANIA), Italy
G. Torrisi
Universitá Mediterranea di Reggio Calabria, Reggio Calabria, Italy

Along the last twentyfive years, INFN-LNS has gained a relevant role in R&D of plasma-based ion sources. The laboratory is currently involved in the Proton Source and Low Energy Beam Transport (LEBT) line prototype construction for the European Spallation Source. ESS – based on a 2.0 GeV, 62.5 mA proton accelerator for neutron production – will be a fundamental instrument for research and application. The proton source is required to produce at least 90 mA beam (as total drain current) at 0.25 π.mm.mrad emittance, 2.86 ms pulse duration, 14 Hz repetition rate. We will illustrate the advanced design of the machine, including the innovations in plasma heating schemes, the final layout of the LEBT – based on detailed beam transport studies, a new vacuum scheme and the final chopper strategy – and the first steps of the devices installation at the INFN-LNS test-bench site.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA010

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA012

Design of a Microwave Frequency Sweep Interferometer for Plasma Density Measurements in ECR Ion Sources

ion, simulation, diagnostics, ion-source

2512

G. Torrisi, R. Agnello, G. Castro, L. Celona, V. Finocchiaro, S. Gammino, D. Mascali, L. Neri, S. Passarello
INFN/LNS, Catania, Italy
T. Isernia, G. Torrisi
Universitá Mediterranea di Reggio Calabria, Reggio Calabria, Italy
G. Sorbello
University of Catania, Catania, Italy

Electron Cyclotron Resonance Ion Sources (ECRIS) are among the candidates to support the growing request of intense beams of multicharged ions. Their further development is related to the availability of new diagnostic tools, nowadays consisting of few types only of devices designed on purpose for such compact machines. Microwave Interferometry is a non-invasive method for plasma diagnostics and represents the best candidate for the whole plasma density measurements. Interferometry in ECR Ion Sources is a challenging task due to their compact size. The typical density range of ECR plasmas (10¹¹-10¹² cm^-3) causes the probing beam wavelength to be in the order of few centimetres, which is comparable to the chamber radius. The paper describes the design of a new microwave interferometer based on the so-called "frequency sweep" method: the density is here derived by the frequency shift of a beating signal obtained during the fast sweep of both probing and reference microwave signals; inner cavity multipaths contributions can thereby be suppressed by cleaning the spurious frequencies from the beating signal spectrum.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA026

Loading of a Plasma-Wakefield Accelerator Section Driven by a Self-Modulated Proton Bunch

electron, proton, simulation, beam-loading

2551

V.K.B. Olsen, E. Adli
University of Oslo, Oslo, Norway
L.D. Amorim
IST, Lisboa, Portugal
P. Muggli
MPI, Muenchen, Germany
J. Vieira
Instituto Superior Tecnico, Lisbon, Portugal

We investigate beam loading of a plasma wake driven by a self-modulated proton beam using particle-in-cell simulations for phase III of the AWAKE project. We address the case of injection after the proton beam has already experienced self-modulation in a previous plasma. Optimal parameters for the injected electron bunch in terms of initial beam energy and beam charge density are investigated and evaluated in terms of witness bunch energy and energy spread. An approximate modulated proton beam is emulated in order to reduce computation time in these simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA026

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA031

A Compact Multiply Charged Ion Source for Hadrontherapy Facility

ion, injection, ion-source, solenoid

2563

L. Celona, L. Andò, G. Castro, F. Chines, G. Ciavola, S. Gammino, O. Leonardi, D. Mascali, L. Neri, D. Nicolosi, F. Noto, F. Romano, G. Torrisi
INFN/LNS, Catania, Italy
G. Ciavola
CNAO Foundation, Milan, Italy
G. Torrisi
Universitá Mediterranea di Reggio Calabria, Reggio Calabria, Italy

The ion sources, required by medical applications, must provide intense ion beams, with high reproducibility, stability and brightness. AISHa (Advanced Ion Source for Hadrontherapy) is a compact ECRIS whose hybrid magnetic system consists of a permanent Halbach-type hexapole magnet and a set of independently energized superconducting coils. These will be enclosed in a compact cryostat with two cryocoolers to operate without LHe. The microwave injection system has been designed for maximizing the beam quality through a fine frequency tuning within the 17.3-18.4 GHz band which is possible by using an innovative variable frequency klystron. The introduction of an integrated oven will allow the production of metal ions beams with relatively high intensity. “Accel-decel” extraction system will be used. The LEBT line will consist of a solenoid and a 90° dipole for ions selection. Two diagnostic boxes, made of Faraday cups, beam wires and slits, will allow the investigation of the beam composition and its properties. Moreover, a system of scintillating screens and CCD cameras, placed after the solenoid will allow the investigation of the Frequency Tuning Effect on the source performances.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA031

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA033

Characterization of Laser-plasma Accelerated Electron Beam for a Compact Storage Ring

laser, electron, target, storage-ring

2569

S. H. Park, Y. Cha, Y.U. Jeong, J.S. Jo, H.N. Kim, K.N. Kim, K. Lee, W.J. Ryu, J.S. Shinn, N. Vinokurov
KAERI, Daejon, Republic of Korea
N. Vinokurov
BINP SB RAS, Novosibirsk, Russia

A compact radiation source can be utilized by an electron beam from a Laser-plasma acceleration combined with localized shielding in a small laboratory. The stability of synchrotron radiation in wavelength and power depends on the shot-to-shot jitters of the energy and charge of an electron beam, which is strongly influenced by the plasma density of target and the jitters of a laser beam. With the 30 TW fs laser in KAERI, the optimization for generating the electron beam have done using the different shape of gas nozzle. We also present the pointing stability and the energy spread of the laser-accelerated electron beams.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA033

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA039

The AWAKE Electron Primary Beam Line

electron, proton, dipole, wakefield

2584

J.S. Schmidt, J. Bauche, B. Biskup, C. Bracco, E. Bravin, S. Döbert, M.A. Fraser, B. Goddard, E. Gschwendtner, L.K. Jensen, O.R. Jones, S. Mazzoni, M. Meddahi, A.V. Petrenko, F.M. Velotti, A.S. Vorozhtsov
CERN, Geneva, Switzerland
U. Dorda
DESY, Hamburg, Germany
L. Merminga, V.A. Verzilov
TRIUMF, Vancouver, Canada
P. Muggli
MPI, Muenchen, Germany

The AWAKE project at CERN is planned to study proton driven plasma wakefield acceleration. The proton beam from the SPS will be used in order to drive wakefields in a 10 m long Rb plasma cell. In the first phase of this experiment, scheduled in 2016, the self-modulation of the proton beam in the plasma will be studied in detail, while in the second phase an external electron beam will be injected into the plasma wakefield to probe the acceleration process. The installation of AWAKE in the former CNGS experimental area and the required optics flexibility define the tight boundary conditions to be fulfilled by the electron beam line design. The transport of low energy (10-20 MeV) bunches of 1.25·10⁹ electrons and the synchronous copropagation with much higher intensity proton bunches (3E11) determines several technological and operational challenges for the magnets and the beam diagnostics. The current status of the electron line layout and the associated equipments are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA039

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA041

Plans for a Linear Paul Trap at Rutherford Appleton Laboratory

multipole, quadrupole, ion, resonance

2590

D.J. Kelliher, S. Machida, D.C. Plostinar, C.R. Prior, S.L. Sheehy
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

For over a decade, Linear Paul Traps (LPT) have been used in the study of accelerator beam dynamics. LPT studies exploit the similarity of the Hamiltonian with that of a beam in a quadrupole channel while having advantages in the flexibility of parameter choice, compactness and low cost. In collaboration with Hiroshima University, LPT research planned at STFC Rutherford Appleton Laboratory in the UK aims to investigate a range of topics including resonance crossing, halo formation, long-term stability studies and space-charge effects. Initially, a conventional quadrupole-based LPT will be built at RAL and used for a variety of experiments. In parallel, a design for a more advanced LPT that incorporates higher order multipoles will be pursued and later constructed. This multipole trap will allow non-linear lattice elements to be simulated and so broaden considerably the range of experiments that can be conducted. These will include the investigation of resonance crossing in non-linear lattices, a more detailed study of halo formation and the effect of detuning with amplitude. In this paper we report on progress made in the project to date and future plans.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA041

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA045

Development of a Spectrometer for Proton Driven Plasma Wakefield Accelerated Electrons at AWAKE

electron, dipole, proton, simulation

2601

L.C. Deacon, S. Jolly, F. Keeble, M. Wing
UCL, London, United Kingdom
B. Biskup
Czech Technical University, Prague 6, Czech Republic
B. Biskup, E. Bravin, A.V. Petrenko
CERN, Geneva, Switzerland
M. Wing
DESY, Hamburg, Germany
M. Wing
University of Hamburg, Hamburg, Germany

The AWAKE experiment is to be constructed at the CERN Neutrinos to Gran Sasso facility (CNGS). This will be the first experiment to demonstrate proton-driven plasma wakefield acceleration. The 400 GeV proton beam from the CERN SPS will excite a wakefield in a plasma cell several metres in length. To observe the plasma wakefield, electrons of 10–20 MeV will be injected into the wakefield following the head of the proton beam. Simulations indicate that electrons will be accelerated to GeV energies by the plasma wakefield. The AWAKE spectrometer is intended to measure both the peak energy and energy spread of these accelerated electrons. Improvements to the baseline design are presented, with an alternative dipole magnet and quadrupole focussing, with the resulting energy resolution calculated for various scenarios. The signal to background ratio due to the interaction of the SPS protons with upstream beam line components is calculated, and CCD camera location, shielding and light transport are considered.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA045

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA047

Emittance Growth in a Plasma Wakefield Accelerator

emittance, electron, scattering, wakefield

2609

Ö. Mete, K. Hanahoe, G.X. Xia
UMAN, Manchester, United Kingdom
M. Labiche
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

The interaction of the witness beam with the surrounding plasma particles and wakefields was studied. The implications of the elastic scattering process on beam emittance and, emittance evolution under the focusing and acceleration provided by plasma wakefields were discussed. Simulations results from GEANT4 are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA047

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA048

Design Studies and Commissioning Plans for PARS Experimental Program

acceleration, wakefield, electron, beam-loading

2612

Ö. Mete, K. Hanahoe, J. Wright, G.X. Xia
UMAN, Manchester, United Kingdom
M. Dover, M. Wigram, J. Zhang
University of Manchester, Manchester, United Kingdom
J.D.A. Smith
Tech-X, Boulder, Colorado, USA

Funding: Science and Technology Facilities Council and Cockcroft Institute Core Grant
PARS (Plasma Acceleration Research Station) is an electron beam driven plasma wakefield acceleration test stand proposed for VELA/CLARA facility in Daresbury Laboratory. In order to optimise various operational configurations, 2D numerical studies were performed by using VSIM for a range of parameters such as bunch length, radius, plasma density and positioning of the bunches with respect to each other for the two-beam acceleration scheme. In this paper, some of these numerical studies and considered measurement methods are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA048

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA059

RF Plasma-Based Ion Source Modeling on Unstructured Meshes

ion, simulation, ion-source, electron

2637

S.A. Veitzer, K.R.C. Beckwith, M. Kundrapu
Tech-X, Boulder, Colorado, USA

Funding: This work was performed under the auspices of the Department of Energy, Office of Basic Energy Sciences Award #DE-SC0009585.
Ion source performance for accelerators and industrial applications can be improved through detailed numerical modeling and simulation. There are a number of technical complexities with developing robust models, including a natural separation of important time scales (rf, electron and ion motion), inclusion of plasma chemistry, and surface effects such as secondary electron emission and sputtering. Due to these computational requirements, it is typically difficult to simulate ion sources with Particle-In-Cell codes. An alternative is to use fluid-based codes coupled with electromagnetics in order to model ion sources. These types of models can simulate plasma evolution and rf-driven flows while maintaining good performance. We show here recent results on modeling the H⁻ ion source for the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) using the fluid plasma modeling code USim. We present new meshing capabilities for generating and parallelizing unstructured computational meshes that have increased our parallel code performance and enabled us to model inductively coupled plasmas for long periods of operation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA059

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA063

Beam-Plasma Effects in Muon Ionization Cooling Lattices

simulation, electron, space-charge, ion

2649

J.S. Ellison, P. Snopok
IIT, Chicago, Illinois, USA

Funding: Work is supported by the U.S. Department of Energy.
New computational tools are essential for accurate modeling and simulation of the next generation of muon based accelerator experiments. One of the crucial physics processes specific to muon accelerators that has not yet been implemented in any current simulation code is beam induced plasma effect in liquid, solid, and gaseous absorbers. We report here on the progress of developing the required simulation tools and applying them to study the properties of plasma and its effects on the beam in muon ionization cooling channels.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA063

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA068

Simulation of Laser Pulse Driven Terahertz Generation in Inhomogeneous Plasmas

radiation, laser, simulation, vacuum

2661

C.M. Miao, T.M. Antonsen
UMD, College Park, Maryland, USA
J. Palastro
Icarus Research, Inc., Bethesda, Maryland, USA

Intense, short laser pulses propagating through inhomogeneous plasma can ponderomotively drive THz radiation. Here we consider a transition radiation mechanism (TRM) for THz generation as a laser pulse crosses a plasma boundary. Full format PIC simulations and theoretical analysis are conducted demonstrating that TRM results in low frequency, broad band, coherent THz radiation. The effect of a density ramp is also considered and shown to enhance the radiated energy.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA068

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWA072

Feasibility of Continuously Focused TeV/m Channeling Acceleration with CNT-Channel

acceleration, electron, wakefield, simulation

2670

Y.-M. Shin
Northern Illinois University, DeKalb, Illinois, USA
A.H. Lumpkin, V.D. Shiltsev, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the DOE contract No. DEAC02-07CH11359 to the Fermi Research Alliance LLC.
Atomic channels in crystals are known to consist of 10 – 100 V/Å potential barriers capable of guiding and collimating a high energy beam and continuously focused acceleration with exceptionally high gradients (TeV/m)*,**,***. However, channels in natural crystals are only angstrom-size and physically vulnerable to high energy interactions. Carbon-based nano-crystals such as carbon-nanotubes (CNTs) and graphenes have a large degree of dimensional flexibility and thermo-mechanical strength, which could be suitable for channeling acceleration of MW beams. Nano-channels of the synthetic crystals can accept a few orders of magnitude larger phase-space volume of channeled particles with much higher thermal tolerance than natural crystals****. Our particle-in-cell simulations with 100 um long effective CNT model indicated that a beam-driven self-acceleration produces 1 – 2 % net energy gain in the quasi-linear regime (off-resonance beam-plasma coupling, np = 1000 nb) with ASTA 50 MeV injector beam parameters. This paper presents current status of CNT-channeling acceleration experiment planned at the Advanced Superconducting Test Accelerator (ASTA) in Fermilab.
* T. Tajima, PRL 59, 1440 (1987)
** P. Chen and R. Noble, slac-pub-4187
*** Y. M. Shin, APL 105, 114106 (2014)
**** Y.M. Shin, D. A. Still, and V. Shiltsev, Phys. Plasmas 20, 123106 (2013)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA072

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPJE001

Optimal Positron-Beam Excited Plasma Wakefields in Hollow and Ion-Wake Channels

electron, positron, wakefield, ion

2674

A. A. Sahai, T.C. Katsouleas
Duke ECE, Durham, North Carolina, USA

Funding: DE-SC-0010012, NSF-PHY-0936278
A positron-beam interacting with the plasma electrons drives radial suck-in, in contrast to an electron-beam driven blow-out in the over-dense regime, n_b>n₀. In a homogeneous plasma, the electrons are radially sucked-in from all the different radii. The electrons collapsing from different radii do not simultaneously compress on-axis driving weak fields. A hollow-channel allows electrons from its channel-radius to collapse simultaneously exciting coherent fields *. We analyze the optimal channel radius. Additionally, the low ion density in the hollow allows a larger region with focusing phase. We have shown the formation of an ion-wake channel behind a blow-out electron bubble-wake. Here we explore positron acceleration in the over-dense regime comparing an optimal hollow-plasma channel to the ion-wake channel **. The condition for optimal hollow-channel radius is also compared. We also address the effects of a non-ideal ion-wake channel on positron-beam excited fields.
* S Lee, T Katsouleas, Phys. Rev. E, vol 64, 045501(R) (2001)
** A A Sahai, T Katsouleas, Non-linear ion-wake excitation by ultra relativistic electron wakefields, in review (http://arxiv.org/pdf/1504.03735v1.pdf)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE001

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPJE011

High Reliability, Long Lifetime, Continuous Wave H⁻ Ion Source

ion, ion-source, electron, extraction

2695

P. Barrows, G.E. Becerra
PNL, Madison, Wisconsin, USA

Funding: Small Business Innovation Research (SBIR) Phase II
Phoenix Nuclear Labs (PNL) is developing a high-current, long-lifetime negative hydrogen (H⁻) ion source in partnership with Fermilab as part of an ion beam injector for future Intensity Frontier particle accelerators. In this application, continuous output with long lifetime and high reliability and efficiency are critical. Existing ion sources at Fermilab rely on plasma-facing electrodes and are limited to lifetimes of a few hundred hours, while requiring relatively high gas loads on downstream components. PNL's H⁻ ion source uses an electrodeless microwave plasma generator which has been extensively developed in PNL's positive ion source systems, demonstrating 1000+ hours of operation and >99% continuous uptime. A magnetic filter preferentially blocks energetic electrons produced in the plasma, while allowing cold electrons and fast neutrals through toward a cesiated surface converter to produce the desired H⁻ ions, which are extracted into a low energy beam using electrostatic lenses. The design specifications are 5-10 mA of continuous H⁻ current at 30 keV with <0.2 pi-mm-mrad beam emittance. Construction and testing of the H⁻ ion source is underway at PNL.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE011

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPJE024

Progress on the Study of Direct Laser Electron Acceleration in Density-Modulated Plasma Waveguides

electron, laser, simulation, acceleration

2723

M.W. Lin, B.W. Morgan
The Pennsylvania State University, University Park, Pennsylvania, USA
S.-H. Chen, C.-Y. Hsieh, Y.-L. Liu
NCU, Chung Li, Taiwan
I. Jovanovic
Penn State University, University Park, Pennsylvania, USA

Funding: This work is supported by the United States Defense Threat Reduction Agency through contract HDTRA1-11-1-0009 and the Ministry of Science and Technology in Taiwan by Grant No. MOST103-2112-M-008-004.
Direct laser acceleration of electrons can be achieved by utilizing the axial field of a guided, radially polarized laser pulse in a density-modulated plasma waveguide*. When a short fs electron bunch is injected, our particle-in-cell simulations show that the electrostatic field, arising from plasma electrons perturbed by the laser ponderomotive force, increases the transverse divergence of the bunch electrons**. Simulations are performed to study the method in which a precursor electron bunch is introduced prior to the main accelerated bunch. The precursor induces a focusing electrostatic field in the background plasma, which can considerably reduce the transverse expansion of the accelerated electrons. Based on the ignitor-heater scheme, density-modulated plasma waveguides are produced in experiments with high-Z gas targets and used to test the guiding of laser pulses. Supersonic gas jet nozzles for producing gas targets are simulated, designed, and then fabricated via direct digital deposition manufacturing. Surface quality of the nozzles and the produced gas target density profiles are evaluated with computerized tomography and optical interferometry, respectively.
* A. G. York, et al., Phys. Rev. Lett. 100, 195001 (2008).
** M.-W. Lin et al., Phys. Plasmas 21, 093109 (2014)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE024

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMA059

Degassing of Kicker Magnet by In-situ Bake-out Method

vacuum, kicker, radiation, shielding

2911

J. Kamiya, Y. Hikichi, M. Kinsho, N. Ogiwara
JAEA/J-PARC, Tokai-mura, Japan

New method of in-situ degassing of the kicker magnet in the beam line has been developed. The heater and heat shielding panels are installed in the vacuum chamber in this method. The heater was designed considering the maintainability. The graphite was selected as the heater and the high melting point metals were used as the reflectors just near the heater. The thermal analysis and the temperature measurement with the designed heater was performed. The ideal temperature distribution for the kicker degassing was obtained. The outgassing of the graphite during rising the temperature was measured. The result showed that the outgassing was extremely suppressed by the first heating. This means the outgassing of the graphite heater was negligible as long as it is used in the beam line without exposure to the air.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA059

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA058

Superconducting Coatings Synthesized by CVD/PECVD for SRF Cavities

niobium, superconductivity, SRF, accelerating-gradient

3246

P. Pizzol, P. Chalker, T. Heil
The University of Liverpool, Liverpool, United Kingdom
A.N. Hannah, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G.B.G. Stenning
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

Funding: STFC
Bulk niobium cavities are widely employed in particle accelerators to create high accelerating gradient despite their high material and operation cost. In order to reduce this cost, thin layer of niobium are deposited on a copper cavity, which has lower material cost with higher availability and more importantly higher thermal conductivity. The coating of superconducting cavities currently is synthesized by physical vapour deposition (PVD) method which suffers from lack of conformity. By using chemical vapour deposition (CVD) and plasma enhanced chemical vapour deposition (PECVD) it is possible to deposit thin Nb layers uniformly with density very close to bulk material. This project explores the use of PECVD / CVD techniques to deposit metallic niobium on copper using NbCl5 as precursor and hydrogen as a coreagent. The samples obtained were then characterized via SEM, TEM, SAD, XRD, XPS, and EDX as well as assessing their superconductivity characteristics (RRR and Tc) All the samples deposited are superconductive and polycrystalline; the sample obtained with CVD measured RRR=31 and Tc=7.9 K, while the sample obtained with PECVD exhibited RRR=9 and Tc= 9.4 K. In both cases the films grew in a (100) preferred orientation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA058

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA059

Physical Vapour Deposition of Thin Films for Use in Superconducting RF Cavities

SRF, superconductivity, power-supply, radio-frequency

3249

S. Wilde, B. Chesca
Loughborough University, Loughborough, Leicestershire, United Kingdom
A.N. Hannah, D.O. Malyshev, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G.B.G. Stenning
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The production of superconducting coatings for radio frequency cavities is a rapidly developing field that should ultimately lead to acceleration gradients greater than those obtained by bulk Nb RF cavities. Optimizing superconducting properties of Nb thin-films is therefore essential. Nb films were deposited by magnetron sputtering in pulsed DC mode onto Si (100) and MgO (100) substrates and also by high impulse magnetron sputtering (HiPIMS) onto Si (100), MgO (100) and polycrystalline Cu. The films were characterised using scanning electron microscopy, x-ray diffraction and DC SQUID magnetometry.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA059

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTY062

Multipactor Breakdown Modelling Using an Averaged Version of Furman's SEY Model

multipactoring, simulation, electron, cavity

3419

S.A. Rice, J.P. Verboncoeur
Michigan State University, East Lansing, Michigan, USA

Funding: Work supported by a MSU Strategic Partnership Grant.
Furman's seconday electron yield model is commonly used for the simulation of multipactor in accelerating cavities and other resonant structures. While accurate, the stochastic model requires many Monte Carlo simulations in order to characterize susceptibility to multipactor. This paper generalizes our previous research in characterizing a reduced-order Furman model, in which we replace the stochastic Furman model with a deterministic model based upon the Furman model's underlying statistics. Favorable comparisons between the full Furman model and the reduced-order Furman model are shown for multipactor simulations in a coaxial cavity, and the results are expected to generalize to other geometries.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY062

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWI033

Effects of Plasma Processing on Secondary Electron Yield of Niobium Samples

electron, cavity, gun, vacuum

3558

M. Basovic, S. Popović, M. Tomovic, L. Vušković
ODU, Norfolk, Virginia, USA
F. Čučkov, A. Samolov
University of Massachusetts Boston, Boston, Massachusetts, USA

Impurities deposited on the surface of Nb during both the forming and welding of accelerator cavities add to the imperfections of the sheet metal, which then affects the overall performance of the cavities. This leads to a drop in the Q factor and limits the maximum acceleration gradient achievable per unit length of the cavities. The performance can be improved either by adjusting the fabrication and preparation parameters, or by mitigating the effects of fabrication and preparation techniques used. We have developed the experimental setup to determine Secondary Electron Yield (SEY) from the surface of Nb samples. Our aim is to show the effect of plasma processing on the SEY of Nb. The setup measures the secondary electron energy distribution at various incident angles as measured between the electron beam and the surface of the sample. The goal is to determine the SEY on non-treated and plasma treated surface of electron beam welded samples. Here we describe the experimental setup, plasma treatment device, and fabrication and processing of the Nb samples.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI033

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPWI040

Experiment and Results on Plasma Etching of SRF Cavities

cavity, SRF, niobium, ion

3581

J. Upadhyay, J.J. Peshl, S. Popović, L. Vušković
ODU, Norfolk, Virginia, USA
D.S. Im
Old Dominion University, Norfolk, Virginia, USA
H.L. Phillips, A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA

The inner surfaces of SRF cavities are currently chemically treated (etched or electro polished) to achieve the state of the art RF performance. We designed an apparatus and developed a method for plasma etching of the inner surface for SRF cavities. The process parameters (pressure, power, gas concentration, diameter and shape of the inner electrode, temperature and positive dc bias at inner electrode) are optimized for cylindrical geometry. The etch rate non-uniformity has been overcome by simultaneous translation of the gas point-of-entry and the inner electrode during the processing. A single cell SRF cavity has been centrifugally barrel polished, chemically etched and RF tested to establish a baseline performance. This cavity is plasma etched and RF tested afterwards. The effect of plasma etching on the RF performance of this cavity will be presented and discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI040

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THSMS2

50th Anniversary: Accelerator Conferences in the U.S.

operation, linac, site, FEL

3668

S.O. Schriber
SOS, Eagle, Idaho, USA

50th Anniversary: Accelerator Conferences in the U.S.

Slides THSMS2 [1.063 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THSMS2

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF018

Simulation Studies of Plasma-based Charge Strippers

target, electron, ion, heavy-ion

3721

O.S. Haas
TEMF, TU Darmstadt, Darmstadt, Germany

Calculations on the charge state distributions in different charge stripping media are presented. The main focus of this work is the width and peak efficiency of the final charge state distribution. For equal number densities fully-stripped plasma stripping media achieve much higher charge states than gas stripping media of the same nuclear charge. This is due to the reduced electron capture rates of free target electrons compared to bound target electrons. Furthermore, targets with low nuclear charge like hydrogen achieve higher charge states than targets with high nuclear charge like nitrogen in the case of both a plasma and a gas target. Equal final mean charge states can thus be achieved with lower density for plasmas and targets with low nuclear charge. The widths of the charge state distributions are very similar, slightly smaller for plasmas due to the different scaling of the dielectronic recombination rate. In comparison with calculations and measurements published in literature this work underestimates the width of targets with higher nuclear charge like, e.g., nitrogen gas. This is mainly due to the omission of multiple loss processes in the presented calculations. In the future we intend to expand the methods and models used in this work to improve the agreement with different measurements on charge state distributions in plasmas and gases.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF018

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF103

Current Status of the SANAEM RFQ Accelerator Beamline

rfq, proton, simulation, cavity

3952

G. Turemen, B. Yasatekin
Ankara University, Faculty of Sciences, Ankara, Turkey
Y. Akgun, A.S. Bolukdemir
TAEK, Ankara, Turkey
A. Alacakir
SNRTC, Ankara, Turkey
A. Bozbey, A. Sahin
TOBB ETU, Ankara, Turkey
S. Erhan
UCLA, Los Angeles, California, USA
Ö. Mete
UMAN, Manchester, United Kingdom
S. Ogur, V. Yildiz
Bogazici University, Bebek / Istanbul, Turkey
S. Oz, A. Ozbey, H. Yildiz
Istanbul University, Istanbul, Turkey
G. Unel
UCI, Irvine, California, USA
F. Yaman
IZTECH, Izmir, Turkey

The design and production of the proton beamline of SPP, which aims to educate accelerator physicists and serve as particle accelerator technologies test bench, continues at TAEK-SANAEM as a multi-phase project. For the first phase, the 20 keV protons will be accelerated to 1.3 MeV by a single piece RFQ. Currently, the beam current and stability tests are ongoing for the Inductively Coupled Plasma ion source and the measured magnetic field maps of the Low Energy Beam Transport solenoids are being matched to the RFQ acceptance with various beam configurations of the ion source by using computer simulations. The production of the RFQ cavity was started by using high grade aluminum material which will be subsequently coated by Copper to reduce the RF losses. The installation of the low energy diagnostics box was also completed. On the RF side, the development of the hybrid power supply based on solid state and tetrode amplifiers continues. All RF transmission components are already produced with the exception of the circulator and the power coupling antenna which are in the manufacture and design phases, respectively. The acceptance tests of the produced RF components are ongoing. This work summarizes the design, production and test phases of the above mentioned SPP proton beamline components.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF103

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF104

Design of a Scaled High Duty Factor High Current Negative Penning Surface Plasma Source

cathode, ion, electron, simulation

3956

D.C. Faircloth, S.R. Lawrie, T. Rutter, M. Whitehead, T. Wood
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
V.G. Dudnikov
Muons, Inc, Illinois, USA

The Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL) requires a 60 mA, 2 ms, 50 Hz H− beam. The present source can only deliver the current and pulse length requirements at 25 Hz. At 50 Hz there is too much droop in the beam current. To rectify this, a scaled source is being developed. This paper details the new source design and the experiments conducted that are guiding the design.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF104

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPF143

Saddle Antenna RF Ion Sources for Efficient Positive and Negative Ions Production

ion, extraction, operation, electron

4060

V.G. Dudnikov, R.P. Johnson
Muons, Inc, Illinois, USA
G. Dudnikova
UMD, College Park, Maryland, USA
B. Han, S.N. Murray, T.R. Pennisi, C. Piller, M. Santana, M.P. Stockli, R.F. Welton
ORNL, Oak Ridge, Tennessee, USA

Funding: Work supported in part by US DOE Contract DE-AC05-00OR22725 and by STTR grant DE-SC0011323.
Existing RF Surface Plasma Sources (SPS) for accelerators have specific efficiencies for H⁺ and H⁻ ion generation ~3-5 mA/cm² kW, where about 50 kW of RF power is typically needed for 50 mA beam current production. The Saddle Antenna (SA) SPS described here was developed to improve H⁻ ion production efficiency, reliability and availability. In SA RF ion source the efficiency of positive ion generation in the plasma has been improved to 200 mA/cm² kW. After cesiation, the current of negative ions to the collector was increased from 1 mA to 10 mA with RF power ~1.5 kW in the plasma (6 mm diameter emission aperture) and up to 30 mA with ~4 kW RF. Continuous wave (CW) operation of the SA SPS has been tested on the test stand. The general design of the CW SA SPS is based on the pulsed version. Some modifications were made to improve the cooling and cesiation stability. CW operation with negative ion extraction was tested with RF power up to 1.8 kW from the generator (~1.2 kW in the plasma) with production up to Ic=7 mA. Long term operation was tested with 1.2 kW from the RF generator (~0.8 kW in the plasma) with production of Ic=5 mA, Iex ~15 mA (Uex=8 kV, Uc=14 kV).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF143

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)