FRA —  Advanced Concepts & Techniques   (25-Aug-17   08:30—10:00)
Chair: S. Biedron, Element Aero, Chicago, USA
Paper Title Page
Fresh-Slice X-Ray Free Electron Laser Schemes for Advanced X-Ray Applications  
  • A.A. Lutman, R.N. Coffee, Y. Ding, J.P. Duris, M.W. Guetg, Z. Huang, J. Krzywinski, J.P. MacArthur, A. Marinelli, T.J. Maxwell, S.P. Moeller, J. Zemella
    SLAC, Menlo Park, California, USA
  • N. Berrah
    University of Connecticut, Storrs, Connecticut, USA
  • C. Emma
    UCLA, Los Angeles, USA
  Funding: This work was supported by Department of Energy contract nos DE-AC02-76SF00515 and DE-SC0012376
The novel fresh-slice XFEL scheme grants control on the temporal slice of the electron bunch lasing in each undulator section. The technique relies on a time-dependent electron bunch trajectory impressed by the transverse wakefield of a corrugated structure and subsequent orbit manipulation in the undulator section. Fully saturated double pulses are produced in two different undulator sections. The wavelength of each pulse is controlled by the undulator magnetic strength and the delay between the pulses can be scanned from a few femtosecond advance of the pulse generated on the bunch head in the second section to a picosecond delay provided by the magnetic chicane. Three-color saturated pulses are demonstrated by using three undulator sections and the polarization of the pulse generated in the last section can be controlled by the variable polarization Delta undulator. In this work we also show the early results for the first multi-stage amplification scheme, producing ultra-short single-pulses with a 100-GW power level in the soft X-rays. The multi-stage amplification is also demonstrated to improve the performance in power and pulse duration control for the two-color FEL scheme.
Using the Optical-Klystron Effect to Increase and Measure the Intrinsic Beam Energy Spread in Free-Electron Laser Facilities  
  • E. Prat, S. Reiche, T. Schietinger
    PSI, Villigen PSI, Switzerland
  • E. Ferrari
    EPFL, Lausanne, Switzerland
  We present a setup based on the optical klystron concept consisting of two undulator modules separated by a magnetic chicane, that addresses two issues in free-electron laser (FEL) facilities. On the one hand, it allows an increase of the intrinsic energy spread of the beam at the source, which is useful to counteract the harmful microbunching instability. This represents an alternative method to the more conventional laser heater with the main advantage that no laser system is required. On the other hand, the setup can be used to reconstruct the initial beam energy spread, whose typical values in FEL injectors around 1 keV are very difficult to measure with standard procedures.  
Towards High-Efficiency Industrial FELs  
  • A.Y. Murokh
    RadiaBeam, Santa Monica, California, USA
  • P. Musumeci
    UCLA, Los Angeles, California, USA
  • S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
  • S.D. Webb
    RadiaSoft LLC, Boulder, Colorado, USA
  • A. Zholents
    ANL, Argonne, Illinois, USA
  Funding: DOE Grant No. DE-SC0017102
Free Electron Lasers have achieved prominence as the X-ray light source technology for research applications, but their industrial potential remains largely unexplored, even though FELs could reach wavelength coverage and powers unattainable by active media sources. In response to this challenge, we developed the TESSA (tapering-enhanced stimulated superradiant amplifier) FEL scheme, which enables as much as 50% single-pass beam-to-light energy-conversion efficiency. With strongly tapered helical undulator and stimulated rapid deceleration, TESSA offers an order-of-magnitude improvement over all existing high-efficiency FEL paradigms and beyond the limit of many conventional lasers. The proof-of-concept was recently demonstrated by UCLA in a pilot experiment at 10-μm wavelength, where 35% deceleration efficiency has been achieved in a 50-cm wiggler. The next steps discussed herein, include: the ongoing development of the TESSA high gain amplifier at UV wavelength; a planned transition to SCRF linac driven TESSA oscillator to reach high average powers; and eventually a development of the EUV TESSA oscillator for industrial applications in the semiconductor industry.
slides icon Slides FRA03 [3.313 MB]  
Three-Dimensional Manipulation of the Electron Beam Phase Space for Generating Intense Coherent Radiation in Storage Rings  
  • C. Feng, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  • A. Chao
    SLAC, Menlo Park, California, USA
  Several methods have been developed in the last decade to improve the temporal properties of a storage ring based light source. Most of these methods employ external lasers to manipulate the longitudinal phase space of the electron beam to precisely tailor the properties of the radiation pulses. In this work, we show the possibility of the realization of generating fully coherent intense EUV and x-ray radiation pulses via three-dimensional manipulation of the electron beam phase space in storage rings. Theoretical analysis and numerical simulations show that this technique can be used for the generation of megawatt-scale level, fully-temporal coherent EUV and soft x-ray radiation pulses at a storage ring light source.  
European Plasma Accelerator Design Study EuPRAXIA with FEL & HEP User Areas  
  • P.A. Walker
    DESY, Hamburg, Germany
  Funding: Horizon 2020 Programme from European Union
The Horizon 2020 Project EuPRAXIA (European Plasma Research Accelerator with eXcellence In Applications) aims at producing a design report of a highly compact and cost-effective European facility with a 5 GeV electron beam using plasma as the acceleration medium. The accelerator facility will be based on a laser and/or a beam-driven plasma acceleration approach and will have user areas for FEL user experiments as well as high-energy physics (HEP) detector tests. Other applications such as a compact X-ray source for medical imaging will also be included. EuPRAXIA started in November 2015 and will deliver the design report in October 2019. The contribution will introduce the work up to date, the underlying physics of compact plasma accelerators, and its 16 European partner laboratories and further 22 international associated partners.