Author: Krzywinski, J.    [Krzywiński, J.]
Paper Title Page
THP081 PolFEL — New Facility in Poland 746
 
  • K. Szamota-Leandersson, P.J. Czuma, P. Krawczyk, J. Krzywiński, R. Nietubyć, M. Staszczak, J. Szewiński
    NCBJ, Świerk/Otwock, Poland
  • W. Bal, J. Poznański
    IBB, Warsaw, Poland
  • A. Bartnik, H. Fiedorowicz, K. Janulewicz, N. Palka
    MUT, Warsaw, Poland
  • J.K. Sekutowicz
    DESY, Hamburg, Germany
 
  Funding: European Regional Development Fund ’ Smart Growth
In 2018 funds for the free electron laser PolFEL project was received. PolFEL will be driven by cw operating superconducting linac with SRF electron source. PolFEL will generate THz, IR and VIS-VUV radiation in two beamlines, respectively. In the first one, with electron beam below 80 MeV, the THz/IR radiation source will be generated in permanent magnet supper-radiant undulator, delivering THz radiation in 0.5 to 6 THz range. In the second beam line with up to 180 MeV electrons, the VIS/VUV radiation will be generated in the SASE undulator delivering coherent radiation down to 55 nm wavelength in the third harmonic, with sub-100 fs pulse duration. At the moment, four end-stations are planned. Experiments will be equipped with dedicated Pump-Probe spectrometer system as well. In the project, also, the Inverse Compton Scattering experiment is planned. In this contribution we will describe PolFEL facility in more details.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP081  
About • paper received ※ 29 August 2019       paper accepted ※ 18 September 2019       issue date ※ 05 November 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUP032 Regenerative Amplification for a Hard X-Ray Free-Electron Laser 118
 
  • G. Marcus, Y. Ding, Y. Feng, A. Halavanau, Z. Huang, J. Krzywiński, J.P. MacArthur, R.A. Margraf, T.O. Raubenheimer, D. Zhu
    SLAC, Menlo Park, California, USA
  • V. Fiadonu
    Santa Clara University, Santa Clara, California, USA
 
  Funding: This work was supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515.
An X-ray regenerative amplifier FEL (XRAFEL) utilizes an X-ray crystal cavity to provide optical feedback to the entrance of a high-gain undulator. An XRAFEL system leverages gain-guiding in the undulator to reduce the cavity alignment tolerances and targets the production of longitudinally coherent and high peak power and brightness X-ray pulses that could significantly enhance the performance of a standard single-pass SASE amplifier. The successful implementation of an X-ray cavity in the XRAFEL scheme requires the demonstration of X-ray optical components that can either satisfy large output coupling constraints or passively output a large fraction of the amplified coherent radiation. Here, we present new schemes to either actively Q-switch a diamond Bragg crystal through lattice constant manipulation or passively output couple a large fraction of the stored cavity radiation through controlled FEL microbunch rotation. A beamline design study, cavity stability analysis, and optimization will be presented illustrating the performance of potential XRAFEL configurations at LCLS-II/-HE using high-fidelity simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP032  
About • paper received ※ 24 August 2019       paper accepted ※ 26 August 2019       issue date ※ 05 November 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUP033 Q-Switching of X-Ray Optical Cavities by Using Boron Doped Buried Layer Under a Surface of a Diamond Crystal 122
 
  • J. Krzywiński, Y. Feng, A. Halavanau, Z. Huang, A.M. Kiss, J.P. MacArthur, G. Marcus, T. Sato, D. Zhu
    SLAC, Menlo Park, California, USA
 
  Improvement of the longitudinal coherence of X-ray Free Electron Lasers has been the subject of many recent investigations. The XFEL oscillator (XFELO) and Regenerative Amplifier Free-Electron Laser (RAFEL) schemes offer a pathway to fully coherent, high brightness X-ray radiation. The XFELO and RAFEL consist of a high repetition rate electron beam, an undulator and an X-ray crystal cavity to provide optical feedback. The X-ray cavity will be based on diamond crystals in order to manage a high thermal load. We are investigating a ’Q switching’ mechanism that involves the use of a ’Bragg switch’ to dump the X-ray pulse energy built-up inside an X-ray cavity. In particular, one can use an optical laser to manipulate the diamond crystal lattice constant to control the crystal reflectivity and transmission. It has been shown that a 9 MeV focused boron beam can create a buried layer, approximately 5 microns below surface, with a boron concentration up to 1021 atoms/cm3. Here, we present simulations showing that absorbing laser pulses by a buried layer under the crystal surface would allow creating a transient temperature profile which would be well suited for the ’Q switching’ scheme.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP033  
About • paper received ※ 21 August 2019       paper accepted ※ 29 August 2019       issue date ※ 05 November 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUP035 Sensitivity of LCLS Self-Seeded Pedestal Emission to Laser Heater Strength 126
 
  • G. Marcus, D.K. Bohler, Y. Ding, W.M. Fawley, Y. Feng, E. Hemsing, Z. Huang, J. Krzywiński, A.A. Lutman, D.F. Ratner
    SLAC, Menlo Park, California, USA
 
  Measurements of the soft X-ray, self-seeding spectrum at the LCLS free-electron laser generally display a pedestal-like distribution around the central seeded wavelength that degrades the spectral purity. We have investigated the detailed experimental characteristics of this pedestal and found that it is comprised of two separate components: (1) normal SASE whose total strength is nominally insensitive to energy detuning and laser heater (LH) strength; (2) sideband-like emission whose strength positively correlates with that of the amplified seed and negatively with energy detuning and LH strength. We believe this latter, non-SASE component arises from comparatively long wavelength amplitude and phase modulations of the main seeded radiation line. Its shot-to-shot variability and LH sensitivity suggests an origin connected to growth of the longitudinal microbunching instability on the electron beam. Here, we present experimental results taken over a number of shifts that illustrate the above mentioned characteristics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP035  
About • paper received ※ 28 August 2019       paper accepted ※ 29 August 2019       issue date ※ 05 November 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THP071 Progress in High Power High Brightness Double Bunch Self-Seeding at LCLS-II 726
 
  • A. Halavanau, F.-J. Decker, Y. Ding, C. Emma, Z. Huang, A.K. Krasnykh, J. Krzywiński, A.A. Lutman, G. Marcus, A. Marinelli, A. Ratti, D. Zhu
    SLAC, Menlo Park, California, USA
  • C. Pellegrini
    UCLA, Los Angeles, California, USA
 
  Funding: Work supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515.
We have previosuly shown that we can generate near TW, 15 fs duration, near transform limited X-ray pulses in the 4 to 8 keV photon energy range using the LCLS-II copper linac, two electron bunches, a 4-crystal monochromator/delay line and a fast transverse bunch kicker. The first bunch generates a strong seeding X-ray signal, and the second bunch, initially propagating off-axis, interacts with the seed in a tapered amplifier undulator, where it propagates on axis. In this paper, we investigate the design of the 4-crystal monochromator, acting also as an X-ray delay system, and of the fast kicker, in preparation of the implementation of the system in LCLS-II.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP071  
About • paper received ※ 20 August 2019       paper accepted ※ 26 August 2019       issue date ※ 05 November 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)