Keyword: plasma
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MOYBA01 Limits and Possibilities of Laser Wakefield Accelerators electron, laser, coupling, focusing 16
 
  • W. Leemans
    LBNL, Berkeley, California, USA
  
  This presentation provides an outlook into the future of laser-driven plasma wakefield accelerators. What has been achieved, what more is possible and what are the limits.  
slides icon Slides MOYBA01 [43.465 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOYBA01  
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MOPMW030 High Powered Tests of Dielectric Loaded High Pressure RF Cavities for Use in Muon Cooling Channels accelerating-gradient, cavity, radio-frequency, experiment 460
 
  • B.T. Freemire
    IIT, Chicago, Illinois, USA
  • D.L. Bowring, A. Moretti, D.W. Peterson, A.V. Tollestrup, Y. Torun, K. Yonehara
    Fermilab, Batavia, Illinois, USA
  • A.V. Kochemirovskiy
    University of Chicago, Chicago, Illinois, USA
  • Y. Torun
    Illinois Institute of Technology, Chicago, Illlinois, USA
  
  Funding: This work is supported by the Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359.
Bright muon sources require six dimensional cooling to achieve acceptable luminosities. Ionization cooling is the only known method able to do so within the muon lifetime. One proposed cooling channel, the Helical Cooling Channel, utilizes gas filled radio frequency cavities to both mitigate RF breakdown in the presence of strong, external magnetic fields, and provide the cooling medium. Engineering constraints on the diameter of the magnets within which these cavities operate dictate the radius of the cavities be decreased at their nominal operating frequency. To accomplish this, one may load the cavities with a larger dielectric material. Alumina of purities ranging from 96 to 99.8% was tested in a high pressure RF test cell at the MuCool Test Area at Fermilab. The results of breakdown studies with pure nitrogen gas, and oxygen-doped nitrogen gas indicate the peak surface electric field on the alumina ranges between 10 and 15 MV/m. How these results affect the design of a prototype cooling channel cavity will be discussed. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW030  
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MOPMW031 Beam Test of a Dielectric Loaded High Pressure RF Cavity for Use in Muon Cooling Channels cavity, ion, electron, accelerating-gradient 463
 
  • B.T. Freemire
    IIT, Chicago, Illinois, USA
  • D.L. Bowring, A. Moretti, D.W. Peterson, A.V. Tollestrup, K. Yonehara
    Fermilab, Batavia, Illinois, USA
  • A.V. Kochemirovskiy
    University of Chicago, Chicago, Illinois, USA
  • Y. Torun
    Illinois Institute of Technology, Chicago, Illlinois, USA
  
  Funding: This work is supported by the Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359.
Bright muon sources require six dimensional cooling to achieve acceptable luminosities. Ionization cooling is the only known method able to do so within the muon lifetime. One proposed cooling channel, the Helical Cooling Channel, utilizes gas filled radio frequency cavities to both mitigate RF breakdown in the presence of strong, external magnetic fields, and provide the cooling medium. Engineering constraints on the diameter of the magnets within which these cavities operate dictate the radius of the cavities be decreased at their nominal operating frequency. To accomplish this, one may load the cavities with a larger dielectric material. A 99.5% alumina ring was inserted in a high pressure RF test cell and subjected to an intense proton beam at the MuCool Test Area at Fermilab. The results of the performance of this dielectric loaded high pressure RF cavity will be presented. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW031  
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MOPMY036 High-harmonic mm-Wave Frequency Multiplication using a Gyrocon-like Device cavity, electron, coupling, vacuum 579
 
  • F. Toufexis, V.A. Dolgashev, M.V. Fazio, A. Jensen, S.G. Tantawi, A.R. Vrielink
    SLAC, Menlo Park, California, USA
  • P. Borchard
    Dymenso LLC, San Francisco, USA
  
  Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation.
Traditional linear interaction RF sources, such as Klystrons and Traveling Wave Tubes, fail to produce significant power levels at millimeter wavelengths. This is because their critical dimensions are small compared to the wavelength, and the output power scales as the square of the wavelength. We present a vacuum tube technology, where the device size is inherently larger than the operating wavelength. We designed a low–voltage mm–wave source, with an output interaction circuit based on a spherical sector cavity. This device was configured as a phased-locked frequency multiplier. We report the design and cold test results of a proof-of-principle fifth harmonic frequency multiplier with an output frequency of 57.12 GHz. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY036  
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MOPOW005 First Electron Beam Measurements on COXINEL electron, laser, undulator, quadrupole 712
 
  • T. André, I.A. Andriyash, C. Basset, C. Benabderrahmane, P. Berteaud, S. Bonnin, F. Bouvet, F. Briquez, L. Cassinari, L. Chapuis, M.-E. Couprie, D. Dennetière, Y. Dietrich, M. Diop, J.P. Duval, M.E. El Ajjouri, T.K. El Ajjouri, P. Gattoni, C. Herbeaux, N. Hubert, M. Khojoyan, M. Labat, N. Leclercq, A. Lestrade, A. Loulergue, O. Marcouillé, F. Marteau, P. Pierrot, F. Polack, F. Ribeiro, J.P. Ricaud, P. Rommeluère, M. Sebdaoui, K.T. Tavakoli, M.-A. Tordeux, M. Valléau, J. Vétéran, D. Zerbib, C. de Olivera
    SOLEIL, Gif-sur-Yvette, France
  • S. Bielawski, C. Evain, C. Szwaj
    PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
  • J. Gautier, E. Guillaume, G. Lambert, B. Mahieu, V. Malka, A. Rousse, K. Ta Phuoc, C. Thaury
    LOA, Palaiseau, France
  • E. Roussel
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  
  The ERC grant COXINEL aims at demonstrating experimentally Free Electron Laser (FEL) amplification with electrons generated by laser plasma acceleration (LPA). Because of the still limited electron beam performance (especially energy spread and divergence) in view of the FEL requirements, the electron beam transfer line has been specifically designed with adequate diagnostics and strong focusing variable strength permanent magnet quadrupoles, an energy de-mixing chicane and second set of quadrupoles for further dedicated focusing in the FEL interaction region, in a U20 in-vacuum undulator, enabling to operate at 200 nm with a 180 MeV electron beam. The first observation and transport of electrons in the COXINEL line is presented here.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW005  
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TUOBB02 FACET-II Accelerator Research with Beams of Extreme Intensities positron, electron, linac, damping 1067
 
  • V. Yakimenko, Y. Cai, C.I. Clarke, S.Z. Green, C. Hast, M.J. Hogan, N. Lipkowitz, N. Phinney, G.R. White, G. Yocky
    SLAC, Menlo Park, California, USA
  
  In 2016, the second phase of SLAC's x-ray laser, the LCLS-II, will begin to use part of the tunnel occupied by FACET, and the world's only multi-GeV facility for advanced accelerator research will cease operation. FACET-II is a new test facility to provide DOE with the unique capability to develop advanced acceleration and coherent radiation techniques with high-energy electron and positron beams. FACET-II is an opportunity to build on the decades-long experience developed conducting advanced accelerator R&D at the FFTB and FACET and re-deploy HEP infrastructure in continued service of its mission. FACET-II provides a major upgrade over current FACET capabilities and the breadth of the potential research program makes it truly unique. It will synergistically pursue accelerator science that is vital to the future of both advanced acceleration techniques for High Energy Physics, ultra-high brightness beams for Basic Energy Science, and novel radiation sources for a wide variety of applications. The presentation will discuss FACET-II project status and plans for diverse experimental program.  
slides icon Slides TUOBB02 [17.664 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOBB02  
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TUOBB03 CERN AWAKE Facility Readiness for First Beam proton, laser, electron, diagnostics 1071
 
  • C. Bracco, M. Bernardini, A.C. Butterworth, H. Damerau, S. Döbert, V. Fedosseev, E. Feldbaumer, E. Gschwendtner, W. Höfle, A. Pardons, E.N. Shaposhnikova, H. Vincke
    CERN, Geneva, Switzerland
  
  The AWAKE project at CERN was approved in August 2013 and since then a big effort was made to be able to probe the acceleration of electrons before the "2019-2020 Long Shutdown". The next steps in this challenging schedule will be a dry run of all the beam line systems, at the end of the HW commissioning in June 2016, and the first proton beam sent to the plasma cell one month later. The current status of the project is presented together with an outlook over the foreseen works for operation with electrons in 2018.  
slides icon Slides TUOBB03 [10.682 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOBB03  
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TUPMR032 Initial Commissioning of the Rutherford Appleton Laboratory (RAL) Scaled Negative Penning Ion Source interface, cathode, operation, space-charge 1314
 
  • D.C. Faircloth, S.R. Lawrie, T. Rutter, M. Whitehead, T. Wood
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  A new high duty factor, scaled Penning surface plasma source is being developed at RAL. This paper provides initial commissioning results. A stable high-current (up to 100 A) pulsed discharge is obtained, but the anode overheats, caused by poor thermal contact at elevated temperatures. The overheating anode yields a noisy discharge, with low output current, and makes high duty factor operation impossible. The performance of a thermal interface material for aperture plate (plasma electrode) cooling is detailed. An update on the cathode heaters is provided. The anode to source-body fit is analysed at different temperatures for different combinations of mechanical tolerances. This offers insights when compared to ISIS operational sources. A new anode with modified tolerance dimensions for improved fit is being manufactured and will be tested in June 2016.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR032  
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TUPMR052 Commissioning Preparation of the AWAKE Proton Beam Line proton, laser, experiment, extraction 1374
 
  • J.S. Schmidt, B. Biskup, C. Bracco, B. Goddard, R. Gorbonosov, M. Gourber-Pace, E. Gschwendtner, L.K. Jensen, O.R. Jones, V. Kain, S. Mazzoni, M. Meddahi
    CERN, Geneva, Switzerland
  
  The AWAKE experiment at CERN will use a proton bunch with an momentum of 400 GeV/c from the SPS to drive large amplitude wakefields in a plasma. This will require a ~830 m long transfer line from the SPS to the experiment. The prepa- rations for the beam commissioning of the AWAKE proton transfer line are presented in this paper. They include the detailed planning of the commissioning steps, controls and beam instrumentation specifications as well as operational tools, which are developed for the steering and monitoring of the beam line. The installation of the transfer line has been finished and first beam is planned in summer 2016.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR052  
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TUPMR056 Development and Investigation of Pulsed Pinch Plasmas for the Application as FAIR Plasma Stripper ion, electron, heavy-ion, cathode 1387
 
  • M. Iberler, T. Ackermann, B. Bohlender, C. Hock, J. Jacoby, D. Mann, A. Puth, J. Wiechula
    IAP, Frankfurt am Main, Germany
  • G. Ge
    GSI, Darmstadt, Germany
  
  Funding: This work is supported by BMBF
The planed Facility for Ion Research (FAIR) is a new international accelerator laboratory at the GSI in Darm-stadt, Germany. The main topic at this facility is aimed to heavy ion research. The FAIR project in comparison to the existing facility GSI extends the research area by raising the energy of ion beams. After creation of the ion beam at the ion source the state charge is low. Therefor the demand for acceleration of the beam to the highest possible energy is a highly ionized charge state of the beam. For beam stripping to get higher charge state, the traditional tools are gas stripper and foil stripper [1, 2]. Hence Plasma is suggested to be a stripper medium. In Frankfurt are different kinds of Pinch Plasmas under investigation for Stripper. The constricting effect on the plasma or conductor is produced by the magnetic field pressure resulting from the current or by the Lorentz force produced by the current flowing in its own magnetic field. In addition to separate the high pressure discharge cham-ber of the accelerator a plasma window will be used [3]. This contribution gives an overview of the plasma proper-ties and shows first results of different beam times at the GSI. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR056  
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TUPMY013 Progress on Beam-Plasma Effect Simulations in Muon Ionization Cooling Lattices simulation, scattering, space-charge, emittance 1571
 
  • J.S. Ellison
    IIT, Chicago, Illinois, USA
  • P. Snopok
    Illinois Institute of Technology, Chicago, Illlinois, USA
  
  Funding: Work 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 ※ DOI:10.18429/JACoW-IPAC2016-TUPMY013  
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TUPMY018 Recent Progress of Proton Acceleration at Peking University laser, electron, ion, target 1588
 
  • Q. Liao, Y.X. Geng, C. Lin, H.Y. Lu, W.J. Ma, X.Q. Yan, Y.Y. Zhao
    PKU, Beijing, People's Republic of China
  
  We study the enhanced laser ion acceleration using near critical density plasma lens attached to the front of a solid target. The laser quality is spontaneously improved by the plasma lens and energy density of hot electrons is greatly increased by the direct laser acceleration mechanism. Both factors will induce stronger sheath electric field at the rear surface of the target, which accelerates ions to a higher energy. Particle-in-cell simulations show that proton energy can be increased 2-3 times compared with single solid target. This result provides the opportunities for applications of laser plasma accelerator, such as cancer therapy. Further experiments will soon be carried out on 200 TW laser acceleration system at Peking University.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY018  
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TUPMY019 CLAPA Proton Beam Line in Peking University proton, laser, target, ion 1592
 
  • J.G. Zhu, J.E. Chen, C. Lin, H.Y. Lu, W.J. Ma, L. Tao, X.Q. Yan, K. Zhu
    PKU, Beijing, People's Republic of China
  
  Comparing with the conventional accelerator, the laser plasma accelerator can accelerate ions more effectively and greatly reduce the scale and cost. A laser accelerator− Compact Laser Plasma Accelerator (CLAPA) is being built at Institute of Heavy Ion physics of Peking University. According to the beam parameters from proof of principle experiments and theoretical simulations, we design the beam line for ions transport which is being built now and in the near future we will carry out experimental study with it. The beam line is mainly constituted by quadrupole and analyzing magnets . The quadrupole triplet lens collects protons generated from the target, while the analyzing magnet system will choose the protons with proper energy. The transport is simulated by program TRACK. The beam line is designed to deliver proton beam with the energy of 1~ 40MeV, energy spread of ±1% and 106-8 protons per pulse to satisfy the requirement of different experiments. The transmission efficiency is about 94% when the energy spread is ±1%.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY019  
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TUPMY024 First Test of The Imperial College Gabor (Plasma) Lens prototype at the Surrey Ion Beam centre proton, electron, background, ion 1598
 
  • P.A. Posocco, J.K. Pozimski, Y. Xia
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  • M.J. Merchant
    UoM ICS, Manchester, United Kingdom
  • M.J. Merchant
    The Christie NHS Foundation Trust, Manchester, United Kingdom
  
  Funding: Funding was provided by the Imperial College Confidence in Concepts scheme.
The first plasma (Gabor) lens prototype operating at high electron density was built by the Imperial College London in 2015. In November 2015 the lens was tested at the Ion Beam Centre of the University of Surrey with a 1 MeV proton beam. Over 500 snapshots of the beam hitting a scintillator screen installed 0.5 m downstream of the lens were taken for a wide range of settings. Unexpectedly, instead of over- or underfocusing the incoming particles, the lens converted pencil beams into rings. In addition to the dependence of their radius on the lens settings, periodic features appeared along the circumference, suggesting that the electron plasma was exited into a coherent off-axis rotation. The cause of this phenomenon is under investigation. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY024  
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TUPMY025 Proton-Driven Electron Acceleration in Hollow Plasma electron, proton, acceleration, wakefield 1601
 
  • Y. M. Li, K. Hanahoe, O. Mete Apsimon, T.H. Pacey, G.X. Xia
    UMAN, Manchester, United Kingdom
  
  Funding: President's Doctoral Scholar Award from The University of Manchester.
Proton driven plasma wakefield acceleration has been proposed to accelerate electrons to TeV-scale in a single hundreds of meters plasma section. However, it is difficult to conserve beam quality due to the positively charged driven scheme. In this paper, we demonstrate via simulation that hollow plasma is favourable to maintain the long and stable acceleration and simultaneously be able to achieve low normalized emittance and energy spread of the witness electrons. Moreover, it has much higher beam loading tolerance compared to the uniform case. This will potentially facilitates the acceleration of a large number of particles with high beam quality.
* Caldwell A et al.Nature Physics, 2009, 5(5): 363-367
** K. Lotov, Phys. Rev. ST Accel. Beams, 2010, 13(4): 041301.
*** W. Kimura et al., Phys. Rev. ST Accel. Beams, 2011, 14(4): 041301.
 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY025  
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TUPMY028 Ultra-high Gradient Acceleration in Nano-crystal Channels electron, laser, acceleration, wakefield 1607
 
  • Y.-M. Shin
    Northern Illinois University, DeKalb, Illinois, USA
  • D.M. Farinella, P. Taborek, T. Tajima
    UCI, Irvine, California, USA
  • A.H. Lumpkin, V.D. Shiltsev, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
  • X. Zhang
    Shanghai Institute of Optics and Fine Mechanics, Shanghai, People's Republic of China
  
  Funding: This work was supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. We also thank the FAST Department team for the helpful discussions and technical support.
Crystals behave like a non-equilibrium medium (e.g. plasma), but at a relatively low temperature, if heated by a high-power driving source. The warm dense matter contains many more ions (n0 ~ 1019 - 1023 cm-3) available for plasma acceleration than gaseous plasmas, and can possibly support electric fields of up to 30 TV/m of plasma oscillation*,**,***,****. Atomic lattice spaces in solid crystals are known to consist of 10 - 100 V/Å potential barriers capable of guiding and collimating high energy particles with continuously focused acceleration. Nanostructured crystals (e.g. carbon nanotube) with dimensional flexibilities can accept a few orders of magnitude larger phase-space volume of channeled particles than natural crystals. Our PIC simulation results*****, ****** obtained from two plasma acceleration codes, VORPAL and EPOCH, indicate that in the linear regime the beam-driven and laser-driven electrons channeled in a 100 micro-meter long effective nanotube gain 10 MeV (G = 1 - 10 TeV/m). Experimental tests, including slit-mask beam modulation and pump-probe electron diffraction, are designed in Fermilab and NIU to identify a wakefield effect in a photo-excited crystal.
* Phys. Rev.Lett. 43, 267(1979)
** Phys. Plasmas 15, 103105(2008)
*** Nature Photonics 9, 274(2015)
**** Phys. J. 223, 1037(2014)
***** Appl. Phys. Lett. 105, 114106(2014)
****** Phys. Plasmas 20, 123106(2013) 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY028  
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TUPMY033 Radiation of Charged Particle Flying into Chiral Isotropic Medium polarization, radiation, vacuum, interface 1620
 
  • S.N. Galyamin, A.V. Tyukhtin
    Saint-Petersburg State University, Saint-Petersburg, Russia
  • A.A. Peshkov
    HIJ, Jena, Germany
  
  Funding: Work is supported by the Grant of the Russian Foundation for Basic Research (No. 15-32-20985).
In recent years, the interest to radiation of moving charged particles in media with chiral properties is connected with relatively new and prospective method for diagnostics of biological objects which uses the Cherenkov radiation ' Cherenkov luminescence imaging*. Optical activity (chirality, gyrotropy) is typical or biological matter and is caused by mirrorless structure of molecules. Contrary to such gyrotropic medium as magnetized ionospheric plasma, aforementioned media are isotropic. One distributed model describing the frequency dispersion of isotropic chiral media is Condon model. In this report, we continue the investigation performed in our previous paper** where we dealt with the field produced by uniformly moving charge in infinite chiral isotropic medium. Moreover, we perform generalization of early paper***, where the problem with half-space was considered in the specific case of slow charge motion. We present typical radiation patterns in vacuum area and corresponding ellipses of polarization which allows determination of the chiral parameter of the medium.
* Spinelli A.E. et al. // NIM A. 2011. V. 648. P. S310.
** Galyamin S.N. et al. // Phys. Rev. E. 2013. V. 88. P. 013206.
*** Engheta N., Mickelson A.R. // IEEE Trans. AP. 1982. V. 30. P. 1213.
 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY033  
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TUPOY039 Studies on Electron Linear Accelerator System for Polymer Research electron, linac, coupling, radiation 1985
 
  • E. Kongmon
    IST, Chiang Mai, Thailand
  • N. Kangrang
    Chiang Mai University, PBP Research Facility, Chiang Mai, Thailand
  • S. Rimjaem, J. Saisut, C. Thongbai
    Chiang Mai University, Chiang Mai, Thailand
  • P. Wichaisirimongkol
    Chiang Mai University, Science and Technology Research Institute, Chiang Mai, Thailand
  
  This research focuses on modification of an elec-tron linear accelerator system for irradiation of natural rubber latex and polymeric materials at the Plasma and Beam Physics Research Facility, Chiang Mai Universi-ty, Thailand. This is in order to study the change of material properties due to electron beam irradiation. The main accelerator system consists of a DC thermi-onic electron gun and a short standing-wave linac. This system will be able to produce electron beams with variable energy in the range of 0.5 to 4 MeV. The linac macro pulse frequency is adjustable within the range of 20 to 1000 Hz. The macro pulse duration is 4 μs. The electron pulse current can be varied from 10 to 100 mA. This lead to the electron dose of about 0.44 to 4.4 Gy-m2/min. In this paper, overview of the accelera-tor and the irradiation system is presented. Results of low-level RF measurements of the accelerating struc-ture are also reported and discussed.
This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Material Science, Faculty of science, Chiang Mai University. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY039  
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WEIB06 Industry Role for Advanced Accelerator R&D emittance, cavity, solenoid, linac 2114
 
  • R.P. Johnson
    Muons, Inc, Illinois, USA
  
  Besides large research institutes which typically focus on fundamental research, industrial companies can also contribute to the development of advanced applications of accelerators as well as to fundamental accelerator technology. The funding of advanced or fundamental R&D, which is usually high-risk but potentially high-reward, is difficult to obtain for any organization, especially smaller industrial companies. As an example of one funding approach, I discuss the role of industrial companies in the field of accelerators and present several examples from my own experience of advanced R&D performed by industry under the United States Department of Energy Small Business Innovation and Small Business Technology Transfer Research (SBIR-STTR) Grant programs.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEIB06  
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WEPMB049 Transverse Defocusing Study in LPWA Channel for Linear and Bubble Modes electron, laser, simulation, acceleration 2224
 
  • S.M. Polozov, V.I. Rashchikov, Ya.V. Shashkov
    MEPhI, Moscow, Russia
  
  Laser plasma wakefield acceleration (LPWA) is one of most popular novel trends of acceleration. The LPWA has two serous disadvantages as very high energy spread and low part of electrons capturing into acceleration. The waveguide and klystron type beam pre-modulation schemes was proposed *, ** to growth capturing and to limit the energy spectrum of 2-3 % for 200-300 MeV beam. One interesting effect was detected due to numerical simulation of beam dynamics in plasma channel. Not captured electrons are escape to the channel border fast and this effect should be explained. It was shown that such effect is caused by effective potential function which forms very high defocusing transverse field after its trailing edge. The results of such explanation verified by numerical simulations are discussed in report for linear and bubble LPWA modes.
* S.M. Polozov. NIM A, 729, p.517-521, 2013
** S.M. Polozov. Problems of Atomic Science and Technology. Series: Nuclear Physics Investigations, 6 (88), p. 29- 34, 2013
 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB049  
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WEPMR019 Development of Plasma Cleaning at Cornell University cavity, SRF, experiment, superconductivity 2302
 
  • G.M. Ge, F. Furuta, M. Liepe, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Cornell University is developing the plasma cleaning technology as an alternative cleaning technique for SRF cavity surface preparation. In experiments, we successfully ignited the plasma in a single-cell SRF cavity. However the experiments were limited by the peak electric-fields in the RF coupler. In this paper, we show the analysis of the limitation and propose a new design of the coupler which can eliminate the limitation.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR019  
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WEPMY003 Simulations of the Acceleration of Externally Injected Electrons in a Plasma Excited in the Linear Regime electron, laser, acceleration, experiment 2542
 
  • N. Delerue, C. Bruni, S. Jenzer
    LAL, Orsay, France
  • S. Kazamias, B. Lucas, G. Maynard
    Laboratoire de Physique des Gaz et des Plasmas, Universite Paris-Sud, Orsay, France
  • M. Pittman
    CLUPS, Orsay, France
  
  We have investigated numerically the coupling between a 10 \si{MeV} electron bunch of high charge (§I{> 100}{pc}) with a laser generated accelerating plasma wave. Our results show that a high efficiency coupling can be achieved using a §I{50}{TW}, §I{100}{μ \meter} wide laser beam, yielding accelerating field above §I{1}{ GV/m}. We propose an experiment where these predictions could be tested.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY003  
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WEPMY004 Development of an Injector and a Magnetic Transfer Line in the Framework of Cilex laser, electron, dipole, acceleration 2545
 
  • A. Chancé
    CEA/DSM/IRFU, France
  • T. Audet, B. Cros, P. Lee, G. Maynard
    Laboratoire de Physique des Gaz et des Plasmas, Universite Paris-Sud, Orsay, France
  • M. Bougeard, S. Dobosz-Dufrénoy, A. Maitrallain
    CEA, Gif-sur-Yvette, France
  • N. Delerue
    LAL, Orsay, France
  • O. Delferrière, A. Mosnier, J. Schwindling
    CEA/IRFU, Gif-sur-Yvette, France
  • P. Monot
    CEA/DSM, Gif-sur-Yvette, France
  • A. Specka
    LLR, Palaiseau, France
  
  Funding: Investments for the Future program under reference ANR-10-EQPX-25, by the Triangle de la Physique under contract 2011-086TMULTIPLACCELE, 2012-032TELISA, and by the Labex PALM and P2IO.
Laser plasma accelerators (LPAs) have proven their capability to produce accelerating gradients three orders of magnitude higher than RF cavity-based accelerators. The present challenges of LPAs are to achieve the beam quality and stability required by users and to show the feasibility of plasma staging for high-energy applications. As one of the experiments planned at the PetaWatt laser APOLLON facility, currently under construction in France, aims at testing the two-stage scheme, a dedicated plasma injector which will be used as the first stage has been developed and tested at the UHI100 facility at CEA Saclay. The electron source, as well as the beam characterization line, will be presented and the first results will be discussed. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY004  
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WEPMY005 Upgrades of the Experimental Setup for Electron Beam Self-modulation Studies at PITZ laser, electron, experiment, acceleration 2548
 
  • M. Groß, J. Engel, G. Koss, O. Lishilin, G. Loisch, G. Pathak, S. Philipp, R. Schütze, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • R. Brinkmann, J. Osterhoff
    DESY, Hamburg, Germany
  • F.J. Grüner
    CFEL, Hamburg, Germany
  • F.J. Grüner
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • D. Richter
    HZB, Berlin, Germany
  • C.B. Schroeder
    LBNL, Berkeley, California, USA
  
  The self-modulation instability is fundamental for the plasma wakefield acceleration experiment of the AWAKE collaboration at CERN where this effect is supposed to be used to generate proton bunches short enough for producing high acceleration fields. For ease of experimentation it was decided to set up a supporting experiment at the electron accelerator PITZ (Photo Injector Test facility at DESY, Zeuthen site), given that the underlying physics is the same. The goals are to demonstrate and investigate in detail the self-modulation of long electron beams. In 2015 a first set of experiments was conducted utilizing as key elements a novel cross-shaped lithium plasma cell and an ArF excimer laser for plasma generation. No self-modulation was observed yet because of various experimental shortcomings. The properties of the experimental setup were studied in detail and in this contribution we report about the upgrades which are projected to enable the observation of the self-modulation in the upcoming experimental run.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY005  
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WEPMY006 A High Transformer Ratio Scheme for PITZ PWFA Experiments wakefield, laser, acceleration, simulation 2551
 
  • G. Loisch, M. Groß, H. Huck, A. Oppelt, Y. Renier, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • A. Aschikhin, A. Martinez de la Ossa, J. Osterhoff
    DESY, Hamburg, Germany
  • M. Hochberg, M. Sack
    KIT, Karlsruhe, Germany
  
  In the field of plasma wakefield acceleration (PWFA) significant progress has been made throughout the recent years. However, an important issue in building plasma based accelerators that provide particle bunches suitable for user applications will be a high transformer ratio, i.e. the ratio between maximum accelerating field in the witness and maximum decelerating fields in the driver bunch. The transformer ratio for symmetrical bunches in an overdense plasma is naturally limited to 2*. Theory and simulations show that this can be exceeded using asymmetrical bunches. Experimentally this was proven in RF-structures**, but not in PWFA. To study transformer ratios above this limit in the linear regime of a plasma wake, an experimental scheme tailored to the unique capabilities of the Photoinjector Test Facility Zeuthen PITZ, a 20-MeV electron accelerator at DESY, is being investigated. This includes analytical plasma wakefield calculations, numerical simulations of beam transport and plasma wakefields, as well as preparatory studies on the photocathode laser system and the plasma sources.
* K. L. F. Bane, P. B. Wilson and T. Weiland, AIP Conference Proceedings 127, p. 875, 1984
** C. Jing et al., Physical Review Letters 98, 144801, 2007
 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY006  
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WEPMY007 Plasma Density Profile Characterization for Resonant Plasma Wakefield Acceleration Experiment at SPARC_LAB electron, laser, acceleration, experiment 2554
 
  • F. Filippi
    INFN-Roma1, Rome, Italy
  • M.P. Anania, A. Biagioni, E. Chiadroni, M. Ferrario
    INFN/LNF, Frascati (Roma), Italy
  • A. Cianchi
    INFN-Roma II, Roma, Italy
  • F. Filippi, A. Giribono, A. Mostacci, L. Palumbo
    University of Rome La Sapienza, Rome, Italy
  • F. Filippi, A. Giribono, A. Mostacci, L. Palumbo
    INFN-Roma, Roma, Italy
  • A. Giribono
    University of Rome "La Sapienza", Rome, Italy
  • A. Zigler
    The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem, Israel
  
  New generation of particle accelerators is based on the excitation of large amplitude plasma waves driven by either electron or laser beams, named as Plasma Wakefield Accelerator (PWFA) and Laser Wakefield Accelerator (LWFA), respectively. Future experiments scheduled at the SPARC_LAB test facility aim to demonstrate the acceleration of externally injected high brightness electron beams through both schemes. In particular, in the so-called resonant PWFA a train of more than two driver electron bunches generated with the laser comb technique resonantly excites wakefields into the plasma, the last bunch (witness) is injected at the proper accelerating phase gaining energy from the wake. The quality of the accelerated beam depends strongly on plasma density and its distribution along the acceleration length. The desired density can be achieved with a correct shaping of the capillary in which plasma is formed. The measurements of plasma density, as well as other plasma characteristics, can be performed with spectroscopic measurements of the plasma self emitted light. The measurement of density distribution for hydrogen filled capillaries is here reported.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY007  
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WEPMY008 Towards Awake Applications: Electron Beam Acceleration in a Proton Driven Plasma Wake electron, proton, acceleration, wakefield 2557
 
  • E. Adli
    University of Oslo, Oslo, Norway
  
  The first phases of the AWAKE experiment will study the wake structure and the potential for electron acceleration in a self-modulated proton driver. In AWAKE Run 2, expected to start after the LHC Long Shut Down 2, electron beam acceleration will be studied. Using a single proton driver and a long acceleration stage, an electron bunch will be accelerated to high energies. Demonstrating beam quality preservation and scalable plasma sources will be a significant step towards using proton driven plasma for applications. We report on the plans and preparations for AWAKE Run 2.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY008  
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WEPMY009 Transverse Tolerances of a Multi-Stage Plasma Wakefield Accelerator emittance, simulation, linear-collider, acceleration 2561
 
  • C.A. Lindstrøm, E. Adli, J. Pfingstner
    University of Oslo, Oslo, Norway
  • E. Marín, D. Schulte
    CERN, Geneva, Switzerland
  
  Funding: This work is supported by the Research Council of Norway.
Plasma wakefield acceleration (PWFA) provides GeV/m-scale accelerating fields, ideal for applications such as a future linear collider. However, strong focusing fields imply that a transversely offset beam with an energy spread will experience emittance growth from the energy dependent betatron oscillation. We develop an analytic model for estimating tolerances from this effect, as well as an effective simplified simulation tool in Elegant. Estimations for a proposed 1 TeV PWFA linear collider scheme indicate tight tolerances of order 40 nm and 1 μrad in position and angle respectively. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY009  
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WEPMY010 Considerations for a Drive Beam Scheme for a Plasma Wakefield Linear Collider collider, kicker, linac, lattice 2565
 
  • J. Pfingstner, E. Adli, C.A. Lindstrøm
    University of Oslo, Oslo, Norway
  • E. Marín, D. Schulte
    CERN, Geneva, Switzerland
  
  The potential for high average gradients makes plasma wakefield acceleration (PWFA) an attracting option for future linear colliders. For a beam-driven PWFA collider a sequence of cells has to be supplied with synchronised drive beam bunches. This paper is concerned with the generation, transport and distribution of these drive beam bunches in a so-called drive beam complex for a 3 TeV collider. Based on earlier concepts, several modifications are suggested. The new design includes a superconducting linac and an optimised bunch delay system with a tree structure. To verify the feasibility for the overall complex, a lattice design and tracking studies for the critical bending arc subsystem are presented. Also the feasibility of a compact bunch separation system is shown. The result of these efforts is a drive beam complex that is optimised for construction cost and power efficiency that favours unified lattice solutions.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY010  
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WEPMY011 Compact Laser Plasma Accelerator at Peking University laser, acceleration, electron, target 2569
 
  • L.R.F. Li, J.E. Chen, S.C. Gao, Y.X. Geng, Q. Liao, J B. Liu, H.Y. Lu, X.Q. Yan, Y.Y. Zhao, Y.Y. Zhu
    PKU, Beijing, People's Republic of China
  • Y.R. Shou
    Peking University, School of Physics, Beijing, People's Republic of China
  
  A brand new and solely accelerator based on the interaction physics of high intensity ultrafast laser and plasmas, named Compact LAser Plasma Accelerator (CLAPA), was recently built. The laser system can deliver 5J/25fs @ 800nm pulses with contrast of 10-10. Experiments on electron acceleration is scheduled with the regime of laser wakefield acceleration. The charge and the energy spread of the accelerated electron beams will be concerned mainly. The experiments is planned with gas targets with single and dual stages. For the single stage acceleration, we will try density ramp injection and a loose focusing for a monoenergetic electron beam with more charge for some applications. With the PIC simulations and new injection methods, it is expected to generate GeV/tens pC electron beam with an energy spread of <1%. For the two stage cascaded acceleration, we will focus on the staged acceleration and control of the injection of the second stage, as well as the acceleration length of the second stage by manipulating the parameters of the gas target as well as the laser itself. The far future goal of the second plan is to develop a designable and applicable accelerators.
* W.Lu, Phys. Rev.ST Accel. Beams 10.061301 （2007）
** J. Faure, Nature 431, 541 (2004)
***J.S. Liu, Phys. Rev. Lett 107, 035001 (2011)
 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY011  
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WEPMY014 Feasibility Study of a Laser-Driven High Energy Electron Acceleration in a Long Up-Ramp Density electron, laser, simulation, acceleration 2576
 
  • M. Kim, J. Kim, S.W. Lee, I.H. Nam, H. Suk
    GIST, Gwangju, Republic of Korea
  
  Laser-driven wakefield acceleration (LWFA) has received much attention as it can produce GeV-level high-energy electrons in cm-scale distance*. However, the accelerated electron energies are still limited by several factors, especially by the dephasing problem that is caused by different velocities between the plasma wake wave and the accelerated electron beam. In order to increase the acceleration length restricted by the dephasing problem**, we developed a gas-cell with density-tapering, which is realized by applying different gas pressures into two gas inlets in the gas cell. In this way, the gas density and gradient can be easily controlled in the gas cell. We used the density-tapered gas-cell for laser wakefield acceleration experiments in our laboratory with a 20 TW/40 fs Ti:sapphire laser system***. The results show that the electron energy can be significantly enhanced (about twice) with the tapered density gas-cell, compared with a uniform density conventional gas-cell. In this presentation, we show the experimental results and comparison with two-dimensional (2-D) particle-in-cell (PIC) simulation results.
* W. P. Leemans et al. Phy. Rev. Lett. 113, 245002 (2014).
** M. S. Kim et al. Appl. Phy. Lett. 102, 204103 (2013).
*** I. H. Nam et al. Curr. Appl. Phy. 15, 468 (2015). 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY014  
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WEPMY015 Numerical Studies on Tunable Coherent Radiations with a Laser-Plasma Accelerator electron, laser, radiation, acceleration 2579
 
  • J. Kim, M. Kim, I.H. Nam, H. Suk
    GIST, Gwangju, Republic of Korea
  • M.S. Hur
    UNIST, Ulsan, Republic of Korea
  
  Generation of tunable coherent radiation is numerically investigated via the two-dimensional particle-in-cell (2D-PIC) code developed by UNIST* and SIMPLEX developed by Spring-8. The electron beams can be produced by the laser-driven wakefield acceleration technique. The electron beam energy can be easily adjusted between 450 MeV and 800 MeV with a tapered density plasma on the order of 1×1018 cm-3 while the driving laser power is fixed, and the high-energy electron beams can be sent through the undulator arrays for the coherent light emission. The energy-controllable electron bunches can provide an opportunity to control the radiation wave-length with the fixed gap undulators. For the tapered density profile, a capillary cell with two gas inlets can be used. In this paper, we show some simulation and numerical research results regarding these issues, which reveal the possibility for a tunable light source in the soft X-ray regime.
* M. S. Hur, H. Suk, Phys. Plasmas 18 033102 (2011).
 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY015  
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WEPMY016 Development of RF System for Measuring Plasma Density Modulation of Proton Beam-driven Plasma Wakefield simulation, wakefield, proton, focusing 2582
 
  • S.Y. Kim, M. Chung
    UNIST, Ulsan, Republic of Korea
  
  Proton beam-driven plasma wakefield acceleration technique using the proton beam of Super Proton Syn-chrotron (SPS) at CERN has been actively researched these days. Plasma density modulation due to the proton beam will generate high-gradient's electric field within the modulated plasma. The key role is Self-Modulation Instability (SMI) of the long proton beam. To understand SMI phenomena, we have studied RF system such as heterodyne system for measuring modulated plasma den-sity caused by the SMI. In this work, we design the details of the RF system and optical system of focusing millimetre-sized electromagnetic wave using CODE V and plasma-electromagnetic wave interactions using simulation tools.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY016  
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WEPMY017 Numerical Studies of Self Modulation Instability in the Beam-driven Plasma Wakefield Experiments proton, electron, wakefield, simulation 2585
 
  • K. Moon, M. Chung
    UNIST, Ulsan, Republic of Korea
  
  Proton beam-driven plasma wakefield acceleration was recently proposed as a way to bring electrons to TeV energy range in a single plasma section. When the ultra-relativistic long proton beam propagates into the plasmas, this bunch splits into many small bunches. This phenomenon is known as a Self-Modulation Instability (SMI), and its characteristics depend on the ratio of bunch length and plasma wavelength. In this study, we first introduce a Particle-In-Cell (PIC) code WARP, focusing on the basis of parallel version structure. Through numerical simulations using the WARP, we investigate the characteristics of the SMI and propose possible experimental setup at the Injector Test Facility (ITF) of Pohang Accelerator Laboratory (PAL). Also, we present dependencies of the witness beam quality on both the driver beam and plasma parameters.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY017  
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WEPMY019 AWAKE, the Advanced Proton Driven Plasma Wakefield Acceleration Experiment wakefield, laser, electron, experiment 2588
 
  • P. Muggli
    MPI, Muenchen, Germany
  • C. Bracco
    CERN, Geneva, Switzerland
  
  The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) aims at studying plasma wakefield generation and electron acceleration driven by proton bunches. It is a proof-of-principle R&D experiment at CERN and the world's first proton driven plasma wakefield acceleration experiment. The AWAKE experiment is currently being installed in the former CNGS facility and will use the 400 GeV/c proton beam bunches from the SPS to drive the wakefields in the plasma. The first experiments will focus on the self-modulation instability of the long (rms ~12 cm) proton bunch in the plasma. These experiments are planned for the end of 2016. Later, in 2017/2018, low energy (~15 MeV) electrons will be externally injected to sample the wakefields and be accelerated with GeV/m gradients. The main goals of the experiment will be summarized. A summary of the AWAKE design and construction status will be presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY019  
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WEPMY020 Integration of a Terawatt Laser at the CERN SPS Beam for the AWAKE Experiment on Proton-Driven Plasma Wake Acceleration laser, proton, electron, vacuum 2592
 
  • V. Fedosseev, M. Battistin, E. Chevallay, N. Chritin, V. Clerc, T. Feniet, F. Friebel, F. Galleazzi, P. Gander, E. Gschwendtner, J. Hansen, C. Heßler, M. Martyanov, A. Masi, A. Pardons, F. Salveter, K.A. Szczurek
    CERN, Geneva, Switzerland
  • M. Martyanov, J.T. Moody, P. Muggli
    MPI-P, München, Germany
  
  In the AWAKE experiment a high-power laser pulse ionizes rubidium atoms inside a 10 m long vapor cell thus creating a plasma for proton-driven wakefield acceleration of electrons. Propagating co-axial with the SPS proton beam the laser pulse seeds the self-modulation instability within the proton bunch on the front of plasma creation. The same laser will also generate UV-pulses for production of a witness electron beam using an RF-photoinjector. The experimental area formerly occupied by CNGS facility is being modified to accommodate the AWAKE experiment. A completely new laser laboratory was built, taking into account specific considerations related to underground work. The requirements for AWAKE laser installation have been fulfilled and vacuum beam lines for delivery of laser beams to the plasma cell and RF-photoinjector have been constructed. First results of laser beam hardware commissioning tests following the laser installation will be presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY020  
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WEPMY021 Beam-Plasma Interaction Simulations for the AWAKE Experiment at CERN proton, experiment, wakefield, electron 2596
 
  • A.V. Petrenko, E. Gschwendtner, G. Plyushchev, M. Turner
    CERN, Geneva, Switzerland
  • K.V. Lotov
    BINP SB RAS, Novosibirsk, Russia
  • K.V. Lotov, A. Sosedkin
    NSU, Novosibirsk, Russia
  • G. Plyushchev
    EPFL, Lausanne, Switzerland
  • M. Turner
    TUG/ITP, Graz, Austria
  
  The AWAKE experiment at CERN will be the first proof-of-principle demonstration of the proton-driven plasma wakefield acceleration using the 400 GeV proton beam extracted from the SPS accelerator. The plasma wakefield will be driven by a sequence of sub-millimeter long micro-bunches produced as a result of the self-modulation instability (SMI) of the 12 cm long SPS proton bunch in the 10 m long rubidium plasma with a density corresponding to the plasma wavelength of around 1 mm. A 16 MeV electron beam will be injected into the developing SMI and used to probe the plasma wakefields. The proton beam self-modulation in a wide range of plasma densities and gradients have been studied in detail via numerical simulations. A new configuration of the AWAKE experiment with a small plasma density step is proposed.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY021  
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WEPMY022 Homogeneous Focusing of Train of Short Relativistic Electron Bunches by Plasma Wakefield focusing, wakefield, electron, simulation 2599
 
  • V.I. Maslov, I.N. Onishchenko
    NSC/KIPT, Kharkov, Ukraine
  • I.P. Levchuk (Yarovaya)
    KhNU, Kharkov, Ukraine
  
  The focusing of bunches by wakefield, excited in plasma by resonant sequence of relativistic electron bunches (repetition frequency of the bunches coincides with the plasma frequency), is inhomogeneous. In this paper we investigate wakefield plasma lens, in which all bunches of sequence are focused identically and uniformly, for short relativistic electron bunches. For this it is necessary that the charge of 1-st bunch is smaller in determined times than the charges of the other bunches, the interval between back front of 1-st bunch and 1-st front of 2-nd bunch equals determined value, the interval between back front of N-th bunch and 1-st front of (N+1)-th bunch for all other bunches is multiple to excited wavelength. It is shown that only 1-st bunch is in finite Ez≠0. Other bunches are in zero longitudinal electrical wakefield. Hence the 1-st bunch interchange by energy with wakefield. The subsequent bunches don't interchange by energy with wakefield and the amplitude of wakefield doesn't change along sequence. Radial wake force Fr in regions, occupied by bunches, is approximately constant along bunches.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY022  
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WEPMY023 Self-focusing and Wakefield-focusing of Relativistic Electron Bunches in Plasma focusing, wakefield, electron, space-charge 2602
 
  • V.I. Maslov, I.P. Levchuk (Yarovaya), I.N. Onishchenko
    NSC/KIPT, Kharkov, Ukraine
  
  It was shown that at the wakefield excitation by electron bunch, the length of which is equal to half of the wavelength, the ratio of wakefield focusing to self-focusing is large at the end of the bunch, the shape of which is such that it falls from the current maximum value in the head of the bunch to zero at the end of the bunch. However, the ratio of wakefield focusing to self-focusing tends to zero at the end of the bunch, if the current increases along the bunch from zero in the head of the bunch to a maximum value at the end of the bunch. In the case of homogeneous bunch with sharp edges, the length of which is several plasma wavelength, the self-focusing force Fs is constant along the bunch, and wakefield force of focusing changes from -Fs to Fs. In the case of homogeneous bunch with precursor of half current and length, equal to half of wavelength, focusing of bunch is determined by the homogeneous self-focusing force and wakefield focusing force equals zero. Cases of rectangular and Gaussian bunches, the length of which is equal to half of wavelength, also were considered.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY023  
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WEPMY024 A Spectrometer for Proton Driven Plasma Accelerated Electrons at AWAKE - Recent Developments electron, proton, emittance, simulation 2605
 
  • L.C. Deacon, S. Jolly, F. Keeble, M. Wing
    UCL, London, United Kingdom
  • B. Biskup, A. Goldblatt, S. Mazzoni, A.V. Petrenko
    CERN, Geneva, Switzerland
  • B. Biskup
    Czech Technical University, Prague 6, Czech Republic
  • 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 meters in length. To probe 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. Results of beam tests of the scintillator screen output are presented, along with tests of the resolution of the proposed optical system. The results are used together with a BDSIM simulation of the spectrometer system to predict the spectrometer performance for a range of possible accelerated electron distributions.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY024  
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WEPMY025 iMPACT, Undulator-Based Multi-Bunch Plasma Accelerator undulator, wakefield, electron, simulation 2609
 
  • O. Mete Apsimon, K. Hanahoe, G.X. Xia
    UMAN, Manchester, United Kingdom
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • B. Hidding
    USTRAT/SUPA, Glasgow, United Kingdom
  • J.D.A. Smith
    Tech-X, Boulder, Colorado, USA
  
  Funding: This work is supported by the Cockcroft Institute Core Grant and STFC.
The accelerating gradient measured in laser or electron driven wakefield accelerators can be in the range of 10-100GV/m, which is 2-3 orders of magnitude larger than can be achieved by conventional RF-based particle accelerators. However, the beam quality preservation is still an important problem to be tackled to ensure the practicality of this technology. In this global picture, the main goals of this study are planning and coordinating a physics program, the so-called iMPACT, that addresses issues such as emittance growth mechanisms in the transverse and longitudinal planes through scattering from the plasma particles, minimisation of the energy spread and maximising the energy gain while benchmarking the milestones. In this paper, a summary and planning of the project is introduced and initial multi-bunch simulations were presented. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY025  
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WEPMY026 A Gas-filled Capillary Based Plasma Source for Wakefield Experiments vacuum, high-voltage, experiment, simulation 2613
 
  • O. Mete Apsimon, K. Hanahoe, T.H. Pacey, G.X. Xia
    UMAN, Manchester, United Kingdom
  
  Funding: This work is supported by the University of Manchester Strategic Grant.
A plasma medium can be formed when a gas is discharged via an applied high voltage within a capillary tube. A high voltage discharge based plasma source for plasma wake- field acceleration experiment is being developed. Design considered a glass capillary tube with various inner radii. Glass was preferred to sapphire or quartz options to ease the machining. Electrodes will be attached to the tube using a sealant resistant to high vacuum conditions and baking at high temperatures. Each electrode will be isolated from the neighbouring one using nuts or washers from a thermoplastic polymer insulator material to prevent unwanted sparking outside of the tube. In this paper, general design considerations and possible working points of this plasma source are presented for a range of plasma densities from 1×1020 to 1×1022 m&#8722;3. Consideration was also given to plasma density diagnostic techniques due to critical dependence of accelerating gradient on plasma density. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY026  
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WEPMY027 Feasibility Study of Plasma Wakefield Acceleration at the CLARA Front End Facility experiment, wakefield, simulation, accelerating-gradient 2617
 
  • K. Hanahoe, R.B. Appleby, Y. M. Li, T.H. Pacey, G.X. Xia
    UMAN, Manchester, United Kingdom
  • B. Hidding
    USTRAT/SUPA, Glasgow, United Kingdom
  • B. Kyle
    University of Manchester, Manchester, United Kingdom
  • O. Mete Apsimon
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • J.D.A. Smith
    Tech-X, Boulder, Colorado, USA
  
  Funding: Cockcroft Institute Core Grant and STFC
Plasma wakefield acceleration has been proposed at the CLARA Front End (FE) facility at Daresbury Laboratory. The initial phase of the experiment will acceleration of the tail of a single electron bunch, and the follow-up experiment will study preserving a high quality beam based on a two-bunch acceleration scenario. In this paper, a concept for the initial experiment is outlined and detailed simulation results are presented. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY027  
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WEPMY031 The Production of Negative Carbon Ions with a Volume Cusp Ion Source ion, extraction, ion-source, electron 2620
 
  • S.V. Melanson, M.P. Dehnel, C. Hollinger, P.T. Jackle, J.A. Martin, D.E. Potkins, T.M. Stewart, J.E. Theroux
    D-Pace, Nelson, British Columbia, Canada
  • T.L. Jones, H.C. McDonald, C. Philpott
    BSL, Auckland, New Zealand
  
  Recent progress has been made at the newly commissioned Ion Source Test Facility (ISTF). Phase II, the final phase of the project, was completed in March 2016. First measurements were performed with D-Pace's TRIUMF licensed H− ion source. The source was first characterized with H− and an extraction study of the H− ions was performed. A study of the production of heavy negative ions with volume cusp sources was started. Measurements with helium revealed no negative ions were extracted. Negative carbon ions were produced with acetylene. The beam composition has been analysed with a spectrometer.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY031  
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WEPMY032 A PID Control Algorithm for Filament-Powered Volume-Cusp Ion Sources controls, ion, ion-source, electron 2623
 
  • S.V. Melanson, M.P. Dehnel, C. Hollinger, J.A. Martin, D.E. Potkins
    D-Pace, Nelson, British Columbia, Canada
  • C. Philpott
    BSL, Auckland, New Zealand
  
  Volume-cusp ion sources require a fast and precise control algorithm to ensure the arc current, and thus the beam current is stable for high-power industrial DC operation. Using D-Pace's TRIUMF [1] licensed filament-powered H volume-cusp ion source, a proportional-integral-derivative (PID) control algorithm was implemented that provides a peak-to-peak beam current variation of ±0.45 % and a root mean square error of 0.025 mA for 10.16 mA of beam current over 60 minutes. The PID parameters were tuned for different set points and the performance of the algorithm is compared for the different settings. Measured arc current stability, and measured beam current as a function of time are presented and the algorithm utilized is described in detail.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY032  
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WEPMY035 Preliminary Commissioning Results of the Proton Source for ESS at INFN-LNS proton, diagnostics, electron, vacuum 2628
 
  • L. Celona, L. Allegra, A. Amato, G. Calabrese, A.C. Caruso, G. Castro, F. Chines, G. Gallo, S. Gammino, O. Leonardi, A. Longhitano, G. Manno, S. Marletta, D. Mascali, A. Maugeri, M. Mazzaglia, L. Neri, S. Passarello, G. Pastore, A. Seminara, A.S. Spartà, G. Torrisi, S. Vinciguerra
    INFN/LNS, Catania, Italy
  • S. Di Martino, P. Nicotra
    Si.A.Tel SRL, Catania, Italy
  • A. Longhitano
    ALTEK, San Gregorio (CATANIA), Italy
  • G. Torrisi
    Universitá Mediterranea di Reggio Calabria, Reggio Calabria, Italy
  
  At Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS) - the commissioning of the high intensity Proton Source for the European Spallation Source (PS-ESS) is under way. Preliminary results of plasma diagnostics collected on a testbench called "Flexible Plasma Trap" (FPT) will be correlated to the peculiarities of the magnetic system design and of the microwave injection setup with a view of the possible implications on the beam extraction system. The status of the costruction is presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY035  
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WEPMY036 Laser Ablation Ion Source for Highly Charge-State Ion Beams ion, extraction, laser, target 2632
 
  • N. Munemoto, K. Horioka
    TIT, Yokohama, Japan
  • K. Okamura, S. Takano, K. Takayama
    KEK, Ibaraki, Japan
  • K. Okamura, K. Takayama
    Sokendai, Ibaraki, Japan
  
  The KEK Laser ablation ion source (KEK-LAIS) is un-der development in order to generate highly ionized metal and fully ionized carbon ions for future applica-tions*. Laser ablation experiments have been carried out by using Nd-YAG laser (0.75 J/pulse, 20 ns) at the KEK test bench. Basic parameters such as a charge-state spec-trum and momentum spectrum of the plasma and extract-ed ion beam current have been obtained. Extraction of C ions from the LAIS is described.
* N.Munemoto et al., Rev. Sci. Inst. 85, 02B922 (2014)
 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY036  
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WEPOR030 Gas Filled RF Resonator Hadron Beam Monitor for Intense Neutrino Beam Experiments electron, cavity, radiation, experiment 2733
 
  • K. Yonehara, A.V. Tollestrup, R.M. Zwaska
    Fermilab, Batavia, Illinois, USA
  • R.J. Abrams, R.P. Johnson, G.M. Kazakevich
    Muons, Inc, Illinois, USA
  • H.M. Dinkel
    University of Missouri, Columbia, Columbia, Missouri, USA
  • B.T. Freemire
    IIT, Chicago, Illinois, USA
  
  Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE HEP STTR Grant DE-SC0013795.
MW-class beam facilities are being considered all over the world to produce an intense neutrino beam for fundamental particle physics experiments. A radiation-robust beam monitor system is required to diagnose the primary and secondary beam qualities in high-radiation environments. We have proposed a novel gas-filled RF-resonator hadron beam monitor in which charged particles passing through the resonator produce ionized plasma that changes the permittivity of the gas. The sensitivity of the monitor has been evaluated in numerical simulation. A signal manipulation algorithm has been designed. A prototype system will be constructed and tested by using a proton beam at the MuCool Test Area at Fermilab. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR030  
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THPPA01 Demonstration of the Hollow Channel Plasma Wakefield Accelerator positron, laser, acceleration, wakefield 3202
 
  • S.J. Gessner, J.M. Allen, C.I. Clarke, J.-P. Delahaye, J.T. Frederico, S.Z. Green, C. Hast, M.J. Hogan, N. Lipkowitz, M.D. Litos, B.D. O'Shea, D.R. Walz, V. Yakimenko, G. Yocky
    SLAC, Menlo Park, California, USA
  • E. Adli, C.A. Lindstrøm
    University of Oslo, Oslo, Norway
  • W. An, C.E. Clayton, C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi
    UCLA, Los Angeles, California, USA
  • S. Corde, A. Doche
    LOA, Palaiseau, France
  • W. Lu
    TUB, Beijing, People's Republic of China
  
  Funding: Work supported by DOE contract DE-AC02-76SF00515.
Over the past decade, there has been enormous progress in the field of beam and laser-driven plasma acceleration of electron beams. However, in order for plasma wakefield acceleration to be useful for a high-energy e+e- collider, we need a technique for accelerating positrons in plasma as well. This is a unique challenge, because the plasma responds differently to electron and positron beams, with plasma electrons being pulled through the positron beam and creating a non-linear focusing force. Here, we demonstrate a technique called hollow channel acceleration that symmetrizes the wakefield response to beams of either charge. Using a transversely shaped laser pulse, we create an annular plasma with a fixed radius of 200 μm. We observe the acceleration of a positron bunch with energies up to 33.4 MeV in a 25 cm long channel, indicating an effective gradient greater than 100 MeV/m. This is the first demonstration of a technique that way be used for staged acceleration of positron beams in plasma. 		 
slides icon Slides THPPA01 [5.647 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPPA01  
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THPMR014 Core-halo Limits and Beam Halo-formation Dynamic space-charge, emittance, focusing, resonance 3417
 
  • M. Valette, P.A.P. Nghiem
    CEA/IRFU, Gif-sur-Yvette, France
  • N. Pichoff
    CEA/DSM/IRFU, France
  
  In high intensity linear accelerators, space charge related instabilities and effects are the cause of emittance increase and beam losses. The mechanism of halo formation due to a mismatched beam causing parametric resonances and energy transfer between phase-spaces is one of them. The previously defined one dimensional core-halo limit [1][2] was extended to two dimensional distributions [3][4]. This halo characterization method is applied to a classical case of transport for halo formation studies: the transport of a mismatched beam. Our method provides a core-halo limit that matches the expected halo formation mechanism with a very good precision.
* Appl. Phys. Lett. 104, 074109 (2014)
** Phys. Plasmas, 22, 083115, (2015)
*** IPAC (2015) MOPWA010
**** TBP 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR014  
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THPMW040 Multipactor Discharge in a Resonator as an Active Switch for RF Pulse Compression multipactoring, cavity, electron, klystron 3640
 
  • J.Q. Qiu, S.P. Antipov, C.-J. Jing, A. Kanareykin
    Euclid Beamlabs LLC, Bolingbrook, USA
  • E.V. Ilyakov, I.S. Kulagin, S.V. Kuzikov, A.A. Vikharev
    IAP/RAS, Nizhny Novgorod, Russia
  
  Funding: Phase I DOE SBIR
Pulse compression is a method of increasing the peak power of the microwave pulse at the expense of its length. Over the years a number of pulse compressors had been demonstrated with some being bulky but efficient, like the binary pulse compressor and other being compact but less efficient, like SLED-II. An active pulse compressor had been proposed to increase the efficiency and compression ratio which relies on a high power active switch. Currently there are no practical switches that can work reliably with 100 s of megawatts of power. Most of the switches (ferroelectric, plasma-based, semiconductor) are limited by the breakdown strength of various dielectric inserts. In this paper we report on an active switch development which is based on a pure copper resonator and controlled by a single-side multipactor discharge at a metallic wall in the presence of a resonant DC magnetic field and a normal to metal rf field. The discharge is ignited by external rf power produced by inexpensive 2.45 GHz, 1-5 kW magnetrons. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW040  
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THPMY002 Fabrication of Ferrite-Copper Block by Spark Plasma Sintering (SPS) HOM, vacuum, cavity, higher-order-mode 3654
 
  • Y. Suetsugu, T. Ishibashi, S. Terui
    KEK, Ibaraki, Japan
  • H. Ishizaki, A. Kimura, T. Sawhata
    Metal Technology Co. Ltd., Ibaraki, Japan
  
  A ferrite has been well known as an effective material for absorbing electromagnetic waves. Various types of the ferrite blocks have been actually used in accelerator fields as the higher-order modes (HOMs) absorbers in the vacuum beam pipes. However, one of difficulties in using the ferrite is to bond it to the beam pipes with a sufficient adhesive force, and to assure the contact with a high thermal conductivity in vacuum. The brazing or Hot Isostatic Pressing (HIP) is not so easy owing to a low thermal expansion rate and a relatively low tensile strength of the ferrite. We established a method of fabricating a ferrite block bonded to copper by spark plasma sintering (SPS). The ferrite powders are directly sintered on a copper block in the SPS process together with some metals to relax the thermal stress between them. The sintered ferrite-copper block can be brazed or welded to other metal blocks, or directly on the beam pipes. Here reported are R&D results of the fabrication method, and some experimental results on the properties of the ferrite-copper block.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY002  
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THPOR044 mm-Wave Standing-Wave Accelerating Structures for High-Gradient Tests accelerating-gradient, cavity, experiment, RF-structure 3884
 
  • E.A. Nanni, M. Dal Forno, V.A. Dolgashev, J. Neilson, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  • S.C. Schaub
    MIT, Cambridge, Massachusetts, USA
  • R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
  
  We present the design and parameters of single-cell accelerating structures for high-gradient testing at 110 GHz. The purpose of this work is to study the basic physics of ultrahigh vacuum RF breakdown in high-gradient RF accelerators. The accelerating structures consist of pi-mode standing-wave cavities fed with TM01 circular waveguide mode. The geometry and field shape of these accelerating structures is as close as practical to single-cell standing-wave X-band accelerating structures, more than 40 of which were tested at SLAC. This wealth of X-band data will serve as a baseline for these 110 GHz tests. The structures will be powered from a pulsed MW gyrotron oscillator. One MW of RF power from the gyrotron may allow us to reach a peak accelerating gradient of 400 MeV/m.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR044  
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