B-2 Plasma, Laser, Dielectric and Other Acceleration Schemes
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SUPAF05 Polarized Proton Beams From Laser-Induced Plasmas 46
  • M. Büscher, J. Böker, R. Engels, I. Engin, R. Gebel, A. Hützen, A. Lehrach
    FZJ, Jülich, Germany
  • A.M. Pukhov, J. Thomas
    HHUD, Dusseldorf, Germany
  • T. P. Rakitzis, D. Sofikitis
    University of Crete, Heraklion, Crete, Greece
  Laser-driven particle acceleration has undergone impressive progress in recent years. Nevertheless, one unexplored issue is how the particle spins are influenced by the huge magnetic fields inherently present in the plasmas. In the framework of the JuSPARC (Jülich Short-Pulse Particle and Radiation Center) facility and of the ATHENA consortium, the laser-driven generation of polarized particle beams in combination with the development of advanced target technologies is being pursued. In order to predict the degree of beam polarization from a laser-driven plasma accelerator, particle-in-cell simulations including spin effects have been carried out for the first time. For this purpose, the Thomas-BMT equation, describing the spin precession in electromagnetic fields, has been implemented into the VLPL (Virtual Laser Plasma Lab) code. A crucial result of our simulations is that a target containing pre-polarized hydrogen nuclei is needed for producing highly polarized relativistic proton beams. For the experimental realization, a polarized HCl gas-jet target is under construction the Forschungszentrum Jülich where the degree of hydrogen polarization is measured with a Lamb-shift polarimeter. The final experiments, aiming at the first observation of a polarized particle beam from laser-generated plasmas, will be carried out at the 10 PW laser system SULF at SIOM/Shanghai.  
slides icon Slides SUPAF05 [3.927 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF05  
About • paper received ※ 19 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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SUPAF08 Particle-in-Cell Simulation of a Bunched Electrons Beam Acceleration in a TE113 Cylindrical Cavity Affected by a Static Inhomogeneous Magnetic Field 64
  • E.A. Orozco
    UIS, Bucaramanga, Colombia
  • J.R. Beltrán, J.D. González, V.E. Vergara
    UMAG, Santa Marta, Colombia
  Funding: Universidad Industrial de Santander vice-rectory of research and extension. Mobility program N° Application: 2349
The results of the relativistic full electromagnetic Particle-in-cell (PIC) simulation of a bunched electrons beam accelerated in a TE113 cylindrical cavity in the presence of a static inhomogeneous magnetic field are presented. This type of acceleration is known as Spatial AutoResonance Acceleration (SARA)*. The magnetic field profile is such that it keeps the electrons beam in the acceleration regime along their trajectories. Numerical experiments of bunched electrons beam with the concentrations in the range 108 -109 cm-3 in a linear TE113 cylindrical microwave field of a frequency of 2.45GHz and an amplitude of 15kV /cm show that it is possible accelerate the bunched electrons up to energies of 250keV without serious defocalization effect. A comparison between the data obtained from the full electromagnetic PIC simulations and the results derived from the relativistic Newton-Lorentz equation in a single particle approximation is carried out. This acceleration scheme can be used to produce hard x-ray**.
* Dugar-Zhabon, V. D., & Orozco, E. A. (2009).Physical Review Special Topics-Accelerators and Beams, 12(4), 041301.
** Dugar-Zhabon, V. D., & Orozco, E. A. (2017). (USA Patent: 9,666, 403 )
slides icon Slides SUPAF08 [1.358 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-SUPAF08  
About • paper received ※ 21 October 2018       paper accepted ※ 27 January 2019       issue date ※ 26 January 2019  
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MOPLG01 Challenges in Simulating Beam Dynamics of Dielectric Laser Acceleration 120
  • U. Niedermayer, O. Boine-Frankenheim, T. Egenolf, E. Skär
    TEMF, TU Darmstadt, Darmstadt, Germany
  • A. Adelmann, S. Bettoni, M. Calvi, M.M. Dehler, E. Ferrari, F. Frei, D. Hauenstein, B. Hermann, N. Hiller, R. Ischebeck, C. Lombosi, E. Prat, S. Reiche, L. Rivkin
    PSI, Villigen PSI, Switzerland
  • R.W. Aßmann, U. Dorda, M. Fakhari, I. Hartl, W. Kuropka, F. Lemery, B. Marchetti, F. Mayet, H. Xuan, J. Zhu
    DESY, Hamburg, Germany
  • D.S. Black, P. N. Broaddus, R.L. Byer, A.C. Ceballos, H. Deng, S. Fan, J.S. Harris, T. Hirano, Z. Huang, T.W. Hughes, Y. Jiang, T. Langenstein, K.J. Leedle, Y. Miao, A. Pigott, N. Sapra, O. Solgaard, L. Su, S. Tan, J. Vuckovic, K. Yang, Z. Zhao
    Stanford University, Stanford, California, USA
  • H. Cankaya, A. Fallahi, F.X. Kärtner
    CFEL, Hamburg, Germany
  • D.B. Cesar, P. Musumeci, B. Naranjo, J.B. Rosenzweig, X. Shen
    UCLA, Los Angeles, USA
  • B.M. Cowan
    Tech-X, Boulder, Colorado, USA
  • R.J. England
    SLAC, Menlo Park, California, USA
  • E. Ferrari, L. Rivkin
    EPFL, Lausanne, Switzerland
  • T. Feurer
    Universität Bern, Institute of Applied Physics, Bern, Switzerland
  • P. Hommelhoff, A. Li, N. Schönenberger, R. Shiloh, A.D. Tafel, P. Yousefi
    University of Erlangen-Nuremberg, Erlangen, Germany
  • Y.-C. Huang
    NTHU, Hsinchu, Taiwan
  • J. Illmer, A.K. Mittelbach
    Friedrich-Alexander Universität Erlangen-Nuernberg, University Erlangen-Nuernberg LFTE, Erlangen, Germany
  • F.X. Kärtner
    Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
  • W. Kuropka, F. Mayet
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • Y.J. Lee, M. Qi
    Purdue University, West Lafayette, Indiana, USA
  • E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
  Funding: ACHIP is funded by the Gordon and Betty Moore Foundation (Grant No. GBMF4744). U.N. acknowledges German BMBF Grant No. FKZ:05K16RDB. B.C. acknowledges NERSC, Contract No. DE-AC02-05CH11231.
Dielectric Laser Acceleration (DLA) achieves the high- est gradients among structure-based electron accelerators. The use of dielectrics increases the breakdown field limit, and thus the achievable gradient, by a factor of at least 10 in comparison to metals. Experimental demonstrations of DLA in 2013 led to the Accelerator on a Chip International Program (ACHIP), funded by the Gordon and Betty Moore Foundation. In ACHIP, our main goal is to build an acceler- ator on a silicon chip, which can accelerate electrons from below 100keV to above 1MeV with a gradient of at least 100MeV/m. For stable acceleration on the chip, magnet- only focusing techniques are insufficient to compensate the strong acceleration defocusing. Thus spatial harmonic and Alternating Phase Focusing (APF) laser-based focusing tech- niques have been developed. We have also developed the simplified symplectic tracking code DLAtrack6D, which makes use of the periodicity and applies only one kick per DLA cell, which is calculated by the Fourier coefficient of the synchronous spatial harmonic. Due to coupling, the Fourier coefficients of neighboring cells are not entirely independent and a field flatness optimization (similarly as in multi-cell cavities) needs to be performed. The simu- lation of the entire accelerator on a chip by a Particle In Cell (PIC) code is possible, but impractical for optimization purposes. Finally, we have also outlined the treatment of wake field effects in attosecond bunches in the grating within DLAtrack6D, where the wake function is computed by an external solver.
slides icon Slides MOPLG01 [3.947 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-MOPLG01  
About • paper received ※ 20 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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MOPAG02 Efficient Modeling of Laser Wakefield Acceleration Through the PIC Code Smilei in CILEX Project 160
  • F. Massimo, A. Beck, A. Specka, I. Zemzemi
    LLR, Palaiseau, France
  • J. Derouillat
    Maison de la Simulation, CEA, Gif-sur-Yvette, France
  • M. Grech, F. Pérez
    LULI, Palaiseau, France
  The design of plasma acceleration facilities requires considerable simulation effort for each part of the machine, from the plasma injector and/or accelerator stage(s), to the beam transport stage, from which the accelerated beams will be brought to the users or possibly to another plasma stage. The urgent issues and challenges in simulation of multi-stage acceleration with the Apollon laser of CILEX facility will be addressed. To simulate the beam injection in the second plasma stage, additional physical models have been introduced and tested in the open source Particle in Cell collaborative code Smilei. The efficient initialisation of arbitrary relativistic particle beam distributions through a Python interface allowing code coupling and the self consistent initialisation of their electromagnetic fields will be presented. The comparison between a full PIC simulation and a simulation with a recently developed envelope model, which allows to drastically reduce the computational time, will be also shown for a test case of laser wakefield acceleration of an externally injected electron beam.  
slides icon Slides MOPAG02 [20.462 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-MOPAG02  
About • paper received ※ 15 October 2018       paper accepted ※ 24 October 2018       issue date ※ 26 January 2019  
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TUPAF19 pyaopt Optimization Suite and its Applications to an SRF Cavity Design for UEMs 229
  • A. Liu, P.V. Avrakhov, R.A. Kostin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • C.-J. Jing
    Euclid Beamlabs LLC, Bolingbrook, USA
  Funding: DOE SBIR
In order to achieve sharp, high resolution real-time imaging, electrons in a MeV UEM (ultrafast electron microscope) beamline need to minimize instabilities. The Superconducting RF (SRF) photocathode gun is a promising candidate to produce highly stable electrons for UEM/UED applications. It operates in an ultrahigh Q, CW mode, and dissipates a few watts of RF power, which make it possible to achieve a 10s ppm level of beam stability by using modern RF control techniques. In order to find the best performance of the gun design, an optimization procedure is required. pyaopt is a Python-based optimization suite that supports multi-objective optimizations using advanced algorithms. In this paper, the novel SRF photogun design and its optimizations through pyaopt and Astra’s beam simulations will be discussed.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-TUPAF19  
About • paper received ※ 22 October 2018       paper accepted ※ 15 December 2018       issue date ※ 26 January 2019  
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Study of Electron Cyclotron Resonance Acceleration by Cylindrical TE011 Mode  
  • O. Otero Olarte, E.A. Orozco
    UIS, Bucaramanga, Colombia
  In this work, we present results from analytical and numerical studies of the electron acceleration by a TE011 cylindrical microwave mode in a static homogeneous magnetic field under electron cyclotron resonance (ECR) condition. The stability of the orbits is analyzed using the particle orbit theory. In order to get a better understanding of the interaction wave-particle we decompose the azimuthally electric field component as the superposition of right and left hand circular polarization standing waves. The trajectory, energy and phase-shift of the electron are found through a numerical solution of the relativistic Newton-Lorentz equation in a finite difference method by the Boris method. It is shown that an electron longitudinally injected with an energy of 7 keV in a radial position r=Rc/2, being Rc the cavity radius, is accelerated up to energy of 90 keV by an electric field strength of 14 kV/cm and frequency of 2.45 GHz. This energy can be used to produce X-ray for medical imaging. These results can be used as a starting point for the study the acceleration of electrons in a magnetic field changing slowly in time (GYRAC), which has some important applications as the electron cyclotron resonance Ion proton accelerator (ECR-IPAC) for cancer therapy and to control plasma bunches with relativistic electrons.  
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WEPLG03 Theoretical and Computational Modeling of a Plasma Wakefield BBU Instability 341
  • S.D. Webb, D.L. Bruhwiler, N.M. Cook
    RadiaSoft LLC, Boulder, Colorado, USA
  • A.V. Burov, V.A. Lebedev, S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
  Funding: This work was supported in part by the Department of Energy, Office of Science, Office of High Energy Physics, under contract number DE-SC0018718.
Plasma wakefield accelerators achieve accelerating gradients on the order of the wave-breaking limit, m c2 kp/e, so that higher accelerating gradients correspond to shorter plasma wavelengths. Small-scale accelerating structures, such as plasma and dielectric wakefields, are susceptible to the beam break-up instability (BBU), which can be understood from the Panofsky-Wenzel theorem: if the fundamental accelerating mode scales as b-1 for a structure radius b, then the dipole mode must scale as b-3, meaning that high accelerating gradients necessarily come with strong dipole wake fields. Because of this relationship, any plasma-accelerator-based future collider will require detailed study of the trade-offs between extracting the maximum energy from the driver and mitigating the beam break-up instability. Recent theoretical work* predicts the tradeoff between the witness bunch stability and the amount of energy that can be extracted from the drive bunch, a so-called efficiency-instability relation . We will discuss the beam break-up instability and the efficiency-instability relation and the theoretical assumptions made in reaching this conclusion. We will also present preliminary particle-in-cell simulations of a beam-driven plasma wakefield accelerator used to test the domain of validity for the assumptions made in this model.
* V. Lebedev, A. Burov, and S. Nagaitsev, "Efficiency versus
instability in plasma accelerators", Phys. Rev. Acc. Beams 20, 121301
slides icon Slides WEPLG03 [2.234 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICAP2018-WEPLG03  
About • paper received ※ 01 November 2018       paper accepted ※ 28 January 2019       issue date ※ 26 January 2019  
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