Author: Shi, L.
Paper Title Page
MOPRB056 THz Radiator Based on Photonic Band Gap Crystal for SwissFEL 693
 
  • L. Shi, R. Ischebeck, S. Reiche
    PSI, Villigen PSI, Switzerland
 
  Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 701647.
The electromagnetic radiation in 1-20 THz has many unique properties when it interacts with matter due to its non-ionizing excitation in matter. Especially the dynamics of the excited matter can be probed with the help of X-ray pulses at a free electron laser facility, e.g. SwissFEL, to deepen our understanding of a wide range of phenomena. Due to its high research potential, various means of THz generation have been proposed and demonstrated. We investigate preliminarily here its generation based on a relativistic electron bunch and a photonic band gap crystal (PBG) made of dielectric rods. The PBG provides additional degrees of freedom for the THz pulse tuning. Additionally, the unwanted radiation parts can be damped by the structure in order to minimize the deleterious beam dynamics effects. The crystal also promises the integration of generation, filtering and coupling for transport into a single piece.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB056  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB075 Higher Order Mode Spectra Study of 3.9 GHz Superconducting Radio Frequency Cavities for the European XFEL 1840
 
  • L. Shi, S. Reiche
    PSI, Villigen PSI, Switzerland
  • N. Baboi, A. Sulimov, E. Vogel, T. Wamsat
    DESY, Hamburg, Germany
  • R.M. Jones, N.Y. Joshi
    UMAN, Manchester, United Kingdom
  • P. Pierini
    ESS, Lund, Sweden
 
  Funding: The work is part of EuCARD2 and was partly funded by the European Commission, GA 312453.
It is important to verify both by simulation and experiments the wakefields in superconducting radio frequency (SRF) cavities, which can degrade the electron beam quality considerably or impose excessive heat load if left undamped. In this paper, we investigate the Higher Order Mode (HOM) spectra of the 3.9 GHz SRF cavities, which are assembled in a cryogenic module and are used to linearize the longitudinal phase space of the electron beam in the injector of the European XFEL. The HOM spectra are significantly different from the ones from a single cavity due to the coupling of the modes amongst cavities. The measurements not only provide direct input for the beam dynamics studies but also for the beam instrumentation utilizing these modes. The mode spectra are also investigated with a number of numerical simulations and the comparison with measurements shows favorable agreement.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB075  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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