Keyword: vacuum
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MOP056 Design of Apparatus for a High-Power-Density Diamond Irradiation Endurance Experiment for XFELO Applications ion, radiation, detector, scattering 185
 
  • S.P. Kearney, K.-J. Kim, T. Kolodziej, R.R. Lindberg, D. Shu, Yu. Shvyd'ko, D. Walko, J. Wang
    ANL, Argonne, Illinois, USA
  • S. Stoupin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
We have designed a diamond irradiation setup capable of achieving multiple kW/mm2 power density. The setup was installed at the 7-ID-B beamline at the Advanced Photon Source (APS) for a successful irradiation experiment, testing the capability of diamond to endure x-ray free electron laser oscillator (XFELO) levels of irradiation (≥ 10 kW/mm2) without degradation of Bragg reflectivity.* Focused white-beam irradiation (50 μm x 20 μm spot size at 12.5 kW/mm2 power density) of a diamond single crystal was conducted in a vacuum environment of 1x10-8 Torr for varying durations of time at different spots on the diamond, and also included one irradiation spot during a spoiled vacuum environment of 4x10-6 Torr. Here we present the apparatus used to irradiate the diamond consisting of multiple subassemblies: the fixed masks, focusing optics, gold-coated UHV irradiation chamber, water-cooled diamond holder, chamber positioning stages (with sub-micron resolution) and detector.
* T. Kolodziej et al., Free Electron Laser Conf. 2017.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP056  
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TUP035 CSR Wake Fields and Emittance Growth with a Discontinuous Galerkin Time Domain Method ion, wakefield, radiation, synchrotron 317
 
  • D. A. Bizzozero, H. De Gersem, E. Gjonaj
    TEMF, TU Darmstadt, Darmstadt, Germany
 
  Funding: Work supported by DESY.
Coherent synchrotron radiation (CSR) is an essential consideration in modern accelerators and related electromagnetic structures. We present our current method to examine CSR in the time domain. The method uses a 2D Discontinous Galerkin (DG) discretization in the longitudinal and transverse coordinates (z,x) with a Fourier decomposition in the transverse coordinate y. After summation over modes, this treatment describes all electromagnetic field components at each space-time coordinate (z,x,y,t). Additionally, by alignment of mesh element interfaces along a source reference orbit, DG methods can handle discontinuous or thin sources in the transverse x direction. We present an overview of our method, illustrate it by calculating wake functions for a bunch compressor, and discuss a method for estimating emittance growth from the wake fields in future work.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP035  
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TUP065 Dielectric Laser Acceleration Setup Design, Grating Manufacturing and Investigations Into Laser Induced RF Cavity Breakdowns ion, laser, acceleration, electron 365
 
  • M. Hamberg, D.S. Dancila, M. Jacewicz, J. Ögren
    Uppsala University, Uppsala, Sweden
  • M. Karlsson, A. Rydberg, E. Vargas Catalan
    Uppsala University, Department of Engineering Sciences, Uppsala, Sweden
  • M. Kuittinen, I. Vartiainen
    UEF, Joensuu, Finland
 
  Funding: Work supported by Stockholm-Uppsala Centre for Free Electron Research.
Dielectric laser acceleration (DLA) is the technique utilizing strong electric fields in lasers to accelerate electrons in the proximity of nanoscaled dielectric gratings. The concept was recently demonstrated in experimental studies. Here we describe the experimental DLA investigation setup design including laser system and scanning electron microscope (SEM). We also present the grating manufacturing methods as well investigations into vacuum breakdowns occurring at RF accelerating structures.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP065  
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WEC02 Optimization of Superconducting Undulators for Low Repetition Rate FELs ion, FEL, undulator, electron 411
 
  • J.A. Clarke, K.B. Marinov, B.J.A. Shepherd, N. Thompson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • V. Bayliss, J. Boehm, T.W. Bradshaw, A.J. Brummitt, S.J. Canfer, M.J.D. Courthold, B. Green, T. Hayler, P. Jeffery, C. Lockett, D.S. Wilsher
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  • S. Milward, E.C.M. Rial
    DLS, Oxfordshire, United Kingdom
 
  Superconducting undulators (SCUs) optimized for storage rings and MHz-level FELs require an intermediate beam screen to intercept the power deposited by the electron beam, due to resistive wall wakefields, to prevent magnet quenching. This beam screen increases the magnet gap by around 2 mm which is a significant increase when compared to the typical electron beam aperture of around 5 mm. However, lower repetition rate FELs only deposit of the order of tens of mW/m and so the beam screen is no longer needed resulting in a significant reduction in undulator magnet gap. We have investigated the impact of this reduced magnet gap and found that the magnetic field level increases greatly. For example, an SCU with a 15 mm period and 5 mm aperture optimized for a low repetition rate FEL instead of a storage ring will generate a field of 2.1 T compared to 1.4 T. Such a major increase in undulator performance could have a significant impact on the optimization of FELs. This paper describes how an SCU optimized for application in a FEL will be able to generate magnetic field levels far beyond those currently foreseen for any other magnet technology.  
slides icon Slides WEC02 [6.234 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEC02  
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