• Y.-J. Chen, G.L. Akana, R. Anaya, D. Anderson, D.T. Blackfield, G.J. Caporaso, J. Carroll, E.G. Cook, S. Falabella, G. Guethlein, J.R. Harris, S.A. Hawkins, B. C. Hickman, C. Holmes, S.D. Nelson, B. R. Poole, R.A. Richardson, S. Sampayan, M. Sanders, J. Stanley, S. Sullivan, L. Wang, J.A. Watson
  LLNL, Livermore, California
• D.W. Pearson
  TomoTherapy, Madison
• J.T. Weir
  CPAC, Madison

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

We are developing a compact proton accelerator for cancer treatment by using the dielectric high-gradient insulator wall technology. The goal is to fit the compact dielectric wall proton therapy machine inside a conventional treatment room. To make the proton dielectric wall accelerator (DWA) compact requires a compact proton source capable of delivering protons in a sub-ns bunch. We are testing all the essential DWA components, including the compact proton source, on the First Accelerator System Test (FAST), which is designed to be taken apart and rebuilt many times to increase system performance by using improved components. The proton source being investigated currently is a surface flashover source. Five induction cells with HGI in the acceleration gaps are used to provide the 300-keV, 20-ns injector voltage for the proton injector. The physics design and the configuration of the injector and FAST will be presented.

• B. R. Poole, D.T. Blackfield, Y.-J. Chen, J.R. Harris
  LLNL, Livermore, California
• P.G. O'Shea
  UMD, College Park, Maryland

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Mismatch oscillations resulting from the propagation of space charge waves in intense beams may lead to halo generation and possible beam loss, and modify longitudinal beam dynamics. These oscillations have amplitudes and frequencies different from that of the main beam and are particularly important in machines such as the University of Maryland Electron Ring (UMER), in which the beam dynamics scale to parameters associated with heavy ion fusion drivers. We use the particle-in-cell (PIC) code, LSP, to simulate space charge wave dynamics in an intense electron beam propagating in a smooth focusing channel with 2-D cylindrical symmetry. We examine the evolution of linear and nonlinear density perturbations in the UMER parameter range for both matched and mismatched beams. Comparisons between LSP simulations and numerical models are presented.

• G.J. Caporaso, G.L. Akana, R. Anaya, D.T. Blackfield, J. Carroll, Y.-J. Chen, E.G. Cook, S. Falabella, G. Guethlein, J.R. Harris, S.A. Hawkins, B. C. Hickman, C. Holmes, A. Horner, S.D. Nelson, A. Paul, B. R. Poole, M.A. Rhodes, R.A. Richardson, S. Sampayan, M. Sanders, S. Sullivan, L. Wang, J.A. Watson
  LLNL, Livermore, California
• D.W. Pearson
  TomoTherapy, Madison
• K.M. Slenes
  TPL, Albuquerque, NM
• J.T. Weir
  CPAC, Madison

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livvermore National Laboratory under Contract DE-AC52-07NA27344.

The dielectric wall accelerator* (DWA) system being developed at the Lawrence Livermore National Laboratory (LLNL) uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. High electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The system is capable of accelerating any charge to mass ratio particle. Applications of high gradient proton and electron versions of this accelerator will be discussed. The status of the developmental new technologies that make the compact system possible will be reviewed. These include high gradient vacuum insulators, solid dielectric materials, photoconductive switches and compact proton sources.

*Patents pending.

Slides