Author: Li, Z.
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TUPA80 Cyborg Beamline Development Updates 512
 
  • G.E. Lawler, A. Fukasawa, N. Majernik, J.R. Parsons, J.B. Rosenzweig, Y. Sakai
    UCLA, Los Angeles, California, USA
  • F. Bosco
    Sapienza University of Rome, Rome, Italy
  • Z. Li, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  • B. Spataro
    LNF-INFN, Frascati, Italy
 
  Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE Contract DE-SC0020409.
Xray free electron laser (XFEL) facilities in their current form are large, costly to maintain, and inaccessible due to their minimal supply and high demand. It is then advantageous to consider miniaturizing XFELs through a variety of means. We hope to increase beam brightness from the photoinjector via high gradient operation (>120 MV/m) and cryogenic temperature operation at the cathode (<77K). To this end we have designed and fabricated our new CrYogenic Brightness-Optimized Radiofrequency Gun (CYBGORG). The photogun is 0.5 cell so much less complicated than our eventual 1.6 cell photoinjector. It will serve as a prototype and test bed for cathode studies in a new cryogenic and very high gradient regime. We present here the fabricated structure, progress towards commissioning, and beamline simulations.
 
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA80  
About • Received ※ 02 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 09 October 2022  
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TUPA81 Design of a High-Power RF Breakdown Test for a Cryocooled C-Band Copper Structure 516
 
  • G.E. Lawler, A. Fukasawa, J.R. Parsons, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • Z. Li, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  • A. Mostacci
    Sapienza University of Rome, Rome, Italy
  • E.I. Simakov, T. Tajima
    LANL, Los Alamos, New Mexico, USA
  • B. Spataro
    LNF-INFN, Frascati, Italy
 
  Funding: This work was supported by the DOE Contract DE-SC0020409.
High-gradient RF structures capable of maintaining gradients in excess of 250 MV/m are critical in several concepts for future electron accelerators. Concepts such as the ultra-compact free electron laser (UC-XFEL) and the Cool Copper Collider (C3) plan to obtain these gradients through the cryogenic operation (<77K) of normal conducting copper cavities. Breakdown rates, the most significant gradient limitation, are significantly reduced at these low temperatures, but the precise physics is complex and involves many interacting effects. High-power RF breakdown measurements at cryogenic temperatures are needed at the less explored C-band frequency (5.712 GHz), which is of great interest for the aforementioned concepts. On behalf of a large collaboration of UCLA, SLAC, LANL, and INFN, the first C-band cryogenic breakdown measurements will be made using a LANL RF test infrastructure. The 2-cell geometry designed for testing will be modifications of the distributed coupled reentrant design used to efficiently power the cells while staying below the limiting values of peak surface electric and magnetic fields.
 
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA81  
About • Received ※ 29 July 2022 — Accepted ※ 02 August 2022 — Issue date ※ 08 August 2022  
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WEPA09 A Parallel Automatic Simulation Tool for Cavity Shape Optimization 634
 
  • L. Ge, Z. Li, C.-K. Ng, L. Xiao
    SLAC, Menlo Park, California, USA
  • M. Beall, B.R. Downie, O. Klaas
    Simmetrix Inc., Clifton Park, USA
 
  Funding: U.S. Department of Energy under contract No. DE-SC0018715.
We present a parallel automatic shape optimization workflow for designing accelerator cavities. The newly developed 3D parallel optimization tool Opt3P based on discrete adjoint methods is used to determine the optimal accelerator cavity shape with the desired spectral response. Initial and updated models, meshes, and design velocities of design parameters for defining the cavity shape are generated with Simmetrix tools for mesh generation (MeshSim), geometry modification and query (GeomSim), and user interface tools (SimModeler). Two shape optimization examples using this automatic simulation workflow will be presented here. One is the TESLA cavity with higher-order-mode (HOM) couplers and the other is a superconducting rf (SRF) gun. The objective for the TESLA cavity is to minimize HOM damping factors and for the SRF gun to minimize the surface electric and magnetic fields while maintaining its operating mode frequency at a prescribed value. The results demonstrate that the automatic simulation tool allows an efficient shape optimization procedure with minimal manual operations. All simulations were performed on the NERSC supercomputer Cori system for solution speedup.
 
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA09  
About • Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 08 October 2022
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WEPA26 197 MHz Waveguide Loaded Crabbing Cavity Design for the Electron-Ion Collider 679
 
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • J. Guo, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  • Z. Li
    SLAC, Menlo Park, California, USA
  • B.P. Xiao
    BNL, Upton, New York, USA
 
  The Electron-Ion Collider will require crabbing systems at both hadron and electron storage rings in order to reach the desired luminosity goal. The 197 MHz crab cavity system is one of the critical rf systems of the col-lider. The crab cavity, based on the rf-dipole design, ex-plores the option of waveguide load damping to suppress the higher order modes and meet the tight impedance specifications. The cavity is designed with compact dog-bone waveguides with transitions to rectangular wave-guides and waveguide loads. This paper presents the compact 197 MHz crab cavity design with waveguide damping and other ancillaries.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA26  
About • Received ※ 08 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 06 September 2022
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