Author: Delayen, J.R.
Paper Title Page
WEPA17 Improved Electrostatic Design of the Jefferson Lab 300 kV DC Photogun and the Minimization of Beam Deflection 655
  • M.A. Mamun, D.B. Bullard, J.M. Grames, C. Hernandez-Garcia, G.A. Krafft, M. Poelker, R. Suleiman
    JLab, Newport News, Virginia, USA
  • J.R. Delayen, G.A. Krafft, G.G. Palacios Serrano, S.A.K. Wijethunga
    ODU, Norfolk, Virginia, USA
  Funding: This work is supported by the Department of Energy, under contract DE-AC05-06OR23177, JSA initiatives fund program, and the Laboratory Directed Research and Development program.
An electron beam with high bunch charge and high repetition rate is required for electron cooling of the ion beam to achieve the high luminosity required for the proposed electron-ion colliders. An improved design of the 300 kV DC high voltage photogun at Jefferson Lab was incorporated toward overcoming the beam loss and space charge current limitation experienced in the original design. To reach the bunch charge goal of ~ few nC within 75 ps bunches, the existing DC high voltage photogun electrodes and anode-cathode gap were modified to increase the longitudinal electric field (Ez) at the photocathode. The anode-cathode gap was reduced to increase the Ez at the photocathode, and the anode aperture was spatially shifted with respect to the beamline longitudinal axis to minimize the beam deflection introduced by the geometric asymmetry of the inverted insulator photogun. The electrostatic design and beam dynamics simulations were performed to determine the required modification. Beam-based measurement from the modified gun confirmed the reduction of the beam deflection, which is presented in this contribution.
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DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA17  
About • Received ※ 23 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 05 August 2022 — Issue date ※ 11 August 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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WEPA31 Lower Temperature Annealing of Vapor Diffused Nb3Sn for Accelerator Cavities 695
  • J.K. Tiskumara, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • G.V. Eremeev
    Fermilab, Batavia, Illinois, USA
  • U. Pudasaini
    JLab, Newport News, Virginia, USA
  Nb3Sn is a next-generation superconducting material for the accelerator cavities with higher critical temperature and superheating field, both twice compared to Nb. It promises superior performance and higher operating temperature than Nb, resulting in significant cost reduction. So far, the Sn vapor diffusion method is the most preferred and successful technique to coat niobium cavities with Nb3Sn. Although several post-coating techniques (chemical, electrochemical, mechanical) have been explored to improve the surface quality of the coated surface, an effective process has yet to be found. Since there are only a few studies on the post-coating heat treatment at lower temperatures, we annealed Nb3Sn-coated samples at 800 C - 1000 C to study the effect of heat treatments on surface properties, primarily aimed at removing surface Sn residues. This paper discusses the systematic surface analysis of coated samples after annealing at temperatures between 850 C and 950 C.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA31  
About • Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 02 September 2022
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