Author: Marshall, T.C.
Paper Title Page
MOPPA003 A Coaxial Two-Channel Dielectric Wakefield Structure for Two-Beam Acceleration Experiments at SLAC 248
 
  • G.V. Sotnikov
    NSC/KIPT, Kharkov, Ukraine
  • J.L. Hirshfield
    Yale University, Physics Department, New Haven, CT, USA
  • T.C. Marshall, G.V. Sotnikov
    Omega-P, Inc., New Haven, USA
  • S.V. Shchelkunov
    Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
 
  Funding: Research is supported by U.S. Department of Energy, Office of High Energy Physics
Results of analytical and numerical investigations of a coaxial dielectric wakefield accelerator structure (CDWA) for experiments at FACET (SLAC) on two-beam acceleration are presented. For these experiments it is proposed to use ~1 THz structure with two nested silica cylindrical shells having these diameters: outer shell, OD = 2 mm, ID = 1 mm; inner shell OD = 360 mkm, ID = 100 mkm. A conventional CDWA structure is energized by an annular drive bunch travelling in the annular vacuum channel. At present, FACET has no drive bunch of annular shape which is required for a CDWA. However, our analytical studies and numerical simulations prove clearly that an annular drive bunch can be substituted by a solid bunch having the same charge*. For the simulation we used the SLAC drive bunch parameters: energy is 23 GeV, charge is 3 nC, axial RMS size is 25 mkm, transverse RMS size is 10 mkm. This bunch sets up at the central channel axis an accelerating gradient of ~1 GeV/m. Questions of transverse stability of the solid drive and accelerated bunches in this dielectric accelerator structure are also discussed.
*G.V.Sotnikov, J.L. Hirshfield, T.C. Marshall, S.V. Shchelkunov, "A reciprocity principle for wakefields in a two-channel coaxial dielectric structure" IPAC’12, New Orleans, May 2012, WEPPP004.