Author: Loisch, G.
Paper Title Page
TUPML046 Characterization of Self-Modulated Electron Bunches in an Argon Plasma 1645
 
  • M. Groß, P. Boonpornprasert, Y. Chen, J. Engel, J.D. Good, H. Huck, I.I. Isaev, M. Krasilnikov, X. Li, O. Lishilin, G. Loisch, R. Niemczyk, A. Oppelt, H.J. Qian, Y. Renier, F. Stephan, Q.T. Zhao
    DESY Zeuthen, Zeuthen, Germany
  • R. Brinkmann, A. Martinez de la Ossa, J. Osterhoff
    DESY, Hamburg, Germany
  • F.J. Grüner
    CFEL, Hamburg, Germany
  • F.J. Grüner, A. Martinez de la Ossa
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • T.J. Mehrling, C.B. Schroeder
    LBNL, Berkeley, California, USA
  • I. Will
    MBI, Berlin, Germany
  
  The self-modulation instability is fundamental for the plasma wakefield acceleration experiment of the AWAKE (Advanced Wakefield Experiment) collaboration at CERN where this effect is used to generate proton bunches for the resonant excitation of high acceleration fields. Utilizing the availability of flexible electron beam shaping together with excellent diagnostics including an RF deflector, a supporting experiment was set up at the electron accelerator PITZ (Photo Injector Test facility at DESY, Zeuthen site), given that the underlying physics is the same. After demonstrating the effect* the next goal is to investigate in detail the self-modulation of long (with respect to the plasma wavelength) electron beams. In this contribution we describe parameter studies on self-modulation of a long electron bunch in an argon plasma. The plasma was generated with a discharge cell with densities in the 1013 cm-3 to 1015 cm-3 range. The plasma density was deduced from the plasma wavelength as indicated by the self-modulation period. Parameter scans were conducted with variable plasma density and electron bunch focusing.
* M. Gross et al., "Observation of the self-modulation instabil-ity via time-resolved measurements", accepted for publication at Phys. Rev. Lett. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML046  
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TUPML047 Optimisation of High Transformer Ratio Plasma Wakefield Acceleration at PITZ 1648
 
  • G. Loisch, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, M. Krasilnikov, O. Lishilin, A. Oppelt, Y. Renier, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • R. Brinkmann, A. Martinez de la Ossa, J. Osterhoff
    DESY, Hamburg, Germany
  • F.J. Grüner
    CFEL, Hamburg, Germany
  • F.J. Grüner, A. Martinez de la Ossa
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  
  The transformer ratio, the ratio between maximum accelerating field and maximum decelerating field in the driving bunch of a plasma wakefield accelerator (PWFA), is one of the key aspects of this acceleration scheme. It not only defines the maximum possible energy gain of the PWFA but it is also connected to the maximum percentage of energy that can be extracted from the driver, which is a limiting factor for the efficiency of the accelerator. Since in linear wakefield theory a transformer ratio of 2 cannot be exceeded with symmetrical drive bunches, any ratio above 2 is considered high. After the first demonstration of high transformer ratio acceleration in a plasma wakefield at PITZ, the photoinjector test facility at DESY, Zeuthen site, limiting aspects of the transformer ratio are under investigation. This includes e.g. the occurrence of bunch instabilities, like the transverse two stream instability, or deviations of the experimentally achieved bunch shapes from the ideal.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML047  
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WEPMF061 High Gradient Pulsed Quadrupoles for Novel Accelerators and Space Charge Limited Beam Transport 2505
 
  • C. Tenholt
    CERN, Geneva, Switzerland
  • G. Loisch, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • B. Marchetti
    DESY, Hamburg, Germany
  
  Novel acceleration schemes like plasma wake-field based accelerators demand for high gradient focusing elements to match the Twiss parameters in the plasma to the transport lattice of the conventional accelerator beamlines, with typically much higher beta-functions. There are multiple candidates for achieving high gradient focusing fields, each one having certain drawbacks. Permanent magnets are limited in tunability, plasma lenses might degrade the transverse beam quality significantly and conventional magnets cannot reach very high gradients and often cannot be placed in direct proximity of the plasma accelerator because of their size. In this paper we present design considerations and simulations on compact, high gradient, pulsed quadrupoles, that could be used e.g. for final focusing of space charge dominated bunches into a LWFA (Laser Wake-Field Accelerator) at SINBAD or other facilities with similar demands. The target design gradient is 200 T/m at a physical aperture on the order of 10 mm.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF061  
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