Author: Adolphsen, C.
Paper Title Page
WEEPPB007 Initial Testing of the Mark-0 X-band RF Gun at SLAC 2179
  • A.E. Vlieks, C. Adolphsen, V.A. Dolgashev, J.R. Lewandowski, C. Limborg-Deprey, S.P. Weathersby
    SLAC, Menlo Park, California, USA
  A new X band RF Gun (Mark-0) has been assembled, tuned and is being tested in the ASTA facility at SLAC. This gun has been improved from an earlier gun used in Compton-scattering experiments at SLAC by the introduction of a racetrack dual-input coupler to reduce quadrupole fields. Waveguide-to-coupler irises were also redesigned to reduce surface magnetic fields and therefore peak pulse surface heating. Tests of this photocathode gun will allow us to gain early operational experience for beam tests of a new gun with further improvements (Mark-1) being prepared for SLAC’s X-Band Test Accelerator (XTA) program and the LLNL MegaRay program. Results of current testing up to ≈ 200 MV/m peak surface Electric fields will be presented.  
THPPC040 Improved RF Design for an 805 MHz Pillbox Cavity for the US MuCool Program 3371
  • Z. Li, C. Adolphsen, L. Ge
    SLAC, Menlo Park, California, USA
  • D.L. Bowring, D. Li
    LBNL, Berkeley, California, USA
  Funding: Work supported by US DOE under contract number DE-AC02-05CH11231, and DE-AC02-76SF00515.
Normal conducting RF cavities are required to operate at high gradient in the presence of strong magnetic field in muon ionization cooling channels for a Muon Collider. Experimental studies using an 805 MHz pillbox cavity at MTA of Fermilab has shown significant degradation in gradient performance and damage in the regions that are correlated with high RF fields in magnetic field up to 4 Tesla. These effects are believed to be related to the dark current and/or multipacting activities in the presence of external magnetic field. To improve the performance of the cavity, a new RF cavity with significantly lower surface field enhancement was designed, and will be built and tested in the near future. Numerical analyses of multipacting and dark current were performed using the 3D parallel code Track3P for both the original and new improved cavity profiles in order to gain more insight in understanding of the gradient issues under strong external magnetic field. In this paper, we will present the improved RF design and the dark current and multipacting analyses for the 805 MHz cavity.