Author: Lehnert, U.
Paper Title Page
MOPRI023 Simulation of the ELBE SRF Gun II 636
 
  • P.N. Lu, A. Arnold, U. Lehnert, P. Murcek, J. Teichert, H. Vennekate, R. Xiang
    HZDR, Dresden, Germany
 
  Funding: EuCARD, contract number 227579 German Federal Ministry of Education and Research grant 05 ES4BR1/8 LA³NET, Grant Agreement Number GA-ITN-2011-289191
By combining the code of ASTRA and elegant in a user-friendly interface, a simulation tool is developed for the ELBE SRF Gun II. The photoelectric emission and first acceleration to several MeV in the gun cavity are simulated by ASTRA with a 1D Model, where the space charge effect is considered. The dependence of the beam quality on key parameters is studied, and a compromised optimization for a 77 pC beam is used for further elegant simulation of the beam transport through a dogleg and ELBE Linacs. Proper settings of the magnets and RF phases are the main targets of improving the beam quality. Up to now the best simulation result is an electron bunch with the energy of 47 MeV, energy spread of 66 keV, bunch length of 0.35 ps and transverse emittance of 1.9 μm and 2.7 μm in the two perpendicular directions.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI023  
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TUZA02 THz Facility at ELBE: A Versatile Test Facility for Electron Bunch Diagnostics on Quasi-CW Electron Beams 933
 
  • M. Gensch, B.W. Green, J. Hauser, S. Kovalev, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig
    HZDR, Dresden, Germany
  • A. Al-Shemmary, V. B. Asgekar, T. Golz, H. Schlarb, N. Stojanovic, S. Vilcins
    DESY, Hamburg, Germany
  • A.S. Fisher
    SLAC, Menlo Park, California, USA
  • G. Geloni
    XFEL. EU, Hamburg, Germany
  • A.-S. Müller, M. Schwarz
    KIT, Karlsruhe, Germany
  • N.E. Neumann, D. Plettemeier
    TU Dresden, Dresden, Germany
 
  At the Helmholtz-Zentrum Dresden-Rossendorf near Dresden a quasi-cw low-energy electron linear accelerator based on superconducting radiofrequency technology is operated successfully for more than 10 years. The ELBE accelerator is driving several secondary radiation sources including 2 infrared free electron lasers. A new addition will be a THz facility that aims to make use of super-radiant THz radiation. In its final form the THz facility shall consist of one coherent diffraction radiator and one undulator source which provide high-field THz pulses at unprecedented repetition rates. While the medium term goal is to establish a unique user facility for nonlinear THz science, the THz sources are already used as a test facility for novel diagnostic techniques on quasi-cw electron beams. The progress of the developments is reported and an outlook into future challenges and opportunities is given.  
slides icon Slides TUZA02 [3.041 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUZA02  
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TUPRO044 Bunch Compression of the Low-energy ELBE Electron Beam for Super-radiant THz Sources 1123
 
  • U. Lehnert, P. Michel, R. Schurig
    HZDR, Dresden, Germany
  • A.A. Aksoy
    Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
  • P.E. Evtushenko
    JLab, Newport News, Virginia, USA
  • J.M. Krämer
    Danfysik A/S, Taastrup, Denmark
 
  At the ELBE radiation source two super-radiant THz sources, a broad-band trasnsition/diffraction radiation source and a planar undulator narrow-band sourc are under commissioning. At present the facility is driven from the ELBE linac with a CW electron beam of 100kHz repetition rate and up to 100pC of bunch charge. With the upgraded SRF electron gun bunch charges up to 1nC will become available. For the beam energies in the 20-30 MeV range buch compression into the sub-200 fs range becomes a major challenge. We present beam dynamics calculation of the attempted bunch compression scheme as well as first measurements obtained during the commissioning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO044  
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WEPRO113 Status of the Radiation Source ELBE Upgrade 2233
 
  • P. Michel, T.E. Cowan, U. Lehnert, U. Schramm
    HZDR, Dresden, Germany
 
  ELBE is based on a 40 MeV superconducting Electron Linac able to operate in CW mode and provides manifold secondary user beams. The suite of secondary beams include: two free electron lasers operating in the IR/THz regime; a fast neutron beam; a Bremsstrahlung gamma-ray beam; a low-energy positron beam; and patented single-electron test beams. The primary electron beam is also used for radiobiology research, or in interaction with ultra-intense PW-class lasers. Through 2014 ELBE will be upgraded to a Centre for High Power Radiation Sources. The ELBE beam current was increased to 1.6 mA by using novel solid state RF amplifiers. The concept also contains additional broad and narrow band coherent THz sources and the development of a 500 TW TiSa Laser and even a 1.5 PW diode pumped laser system. Laser plasma electron acceleration and proton acceleration experiments for medical applications are planned. Additionally, coupled electron laser beam experiments like Thomson scattering or injection of ELBE electron into the laser plasma will be done.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO113  
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WEPME003 Two Years Experience with the Upgraded ELBE RF System Driven by 20kW Solid State Amplifier Blocks (SSPA) 2257
 
  • H. Büttig, A. Arnold, A. Büchner, M. Justus, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig, G.S. Staats, J. Teichert
    HZDR, Dresden, Germany
 
  Since January 2012 the Superconducting CW Linac ELBE is equipped and in permanent operation with four 20 kW Solid State Amplifier Blocks. The poster gives an overview on the design of the new RF system and the experience gained within the first two years of operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME003  
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THPRO012 Wakefield-based Dechirper Structures for ELBE 2882
 
  • F. Reimann, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • U. Lehnert, P. Michel
    HZDR, Dresden, Germany
 
  Funding: Federal Ministry of Education and Research
The efficient reduction of the pulse length and the energy width of electron beams plays a crucial role in the generation of short pulses in the range of sub-picoseconds at future light sources. At the radiation source ELBE in Dresden Rossendorf short pulses are required for coherent THz generation and laser-electron beam interaction experiments such as X-ray Thomson scattering. Energy dechirping can be carried out passively by wakefields generated when the electron beam passes through suitable structures, namely corrugated and dielectrically lined cylindrical pipes or dielectrically lined rectangular waveguides (*,**,***). All structures offer the possibility to tune the resulting wakefield and therefore the resulting energy chirp through a variation of purely geometrical or material parameters. In this paper we present a semi-analytical approach to determine the wakefield in dielectrically lined rectangular waveguide, starting with the expression of the electric field in terms of the structure's eigenmodes.
* Bane, Stupakov, SLAC-PUB-14925 (2012)
** Mosnier, Novokhatski, in: Proceedings of PAC97, Vancouver, Canada, 1997
*** Antipov et al., in: Proceedings of IPAC2012, New Orleans, USA, 2012
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO012  
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THPRO055 Electron Beam Final Focus System for Thomson Scattering at ELBE 2995
 
  • J.M. Krämer, F. Bødker, A. Baurichter, M. Budde
    Danfysik A/S, Taastrup, Denmark
  • A. Irman, U. Schramm
    Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
  • U. Lehnert, P. Michel
    HZDR, Dresden, Germany
 
  Funding: This work is part of LA3NET and funded by European Commission under Grant Agreement Number 289191.
The design of an electron beam Final Focus System (FFS) aiming for high-flux laser-Thomson backscattering x-ray sources at ELBE* is presented. A telescope system consisting of four permanent magnet based quadrupoles was found to have significantly less chromatic aberrations than a quadrupole triplet. This allows sub-ps electron beam focusing to match the laser spot size at the interaction point. Focusing properties like the position of the focal plane and the spot size are retained for electron beam energies between 20 and 30 MeV by adjusting the position of the quadrupoles individually on a motorized stage. Since the electron beam is chirped for bunch compression upstream, the rms energy spread is increased to one or two percent and second order chromatic effects must be taken into account. For an emittance of 13 pi mm mrad, we predict rms spot sizes of about 40 um and divergences of about 15 mrad. We also present the design of the permanent magnet quadrupoles to be used for the FFS. Ferromagnetic poles ensure a high field quality and adjustable shunts allow for fine adjustment of the field strength and compensation of deviations in the permanent magnet material.
*A. Jochmann et al., Phys. Rev. Lett. 111 (2013) 114803
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO055  
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