2011 Particle Accelerator Conference - List of Authors (Poole, B. R.)

Paper	Title	Page
WEP032	Beam Transport in a Compact Dielectric Wall Accelerator for Proton Therapy	1552
	Y.-J. Chen, D.T. Blackfield, G.J. Caporaso, S.D. Nelson, B. R. Poole LLNL, Livermore, California, USA
	Funding: This work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA2A27344. To attain the highest accelerating gradient in the compact dielectric wall (DWA) accelerator, the accelerating voltage pulses should have the shortest possible duration. To do so, the DWA will be operated in the “virtual” traveling mode. Since only a short section of HGI wall would be excited, the accelerating field’s axial profile could be non-uniform and time dependent, especially near the entrance and exit of the DWA, which could lead to dispersion in beam acceleration and transport, and eventually emittance growth. The dispersive transverse kick on a short proton bunch at the DWA entrance and its impact on acceptable input proton bunch length will be discussed. Without using any external lenses, the dispersive transverse kicks on the beam can be mitigated. Implementing the mitigations into the transport strategy, we have established a baseline transport case. Results of simulations using 3-D, EM PIC code, LSP* indicate that the DWA transport performance meets the medical specifications for intensity modulation proton treatment. Sensitivity of the transport performance to the switch timing will be presented. * G. J. Caporaso, Y-J Chen and S. E. Sampayan, "The Dielectric Wall Accelerator", Rev. of Accelerator Science and Technology, vol. 2, p. 253 (2009). ** Alliant Techsystems Inc., http://www.lspsuite.com/.

WEP184	Cerenkov Radiator Driven by a Superconducting RF Electron Gun	1831
	B. R. Poole LLNL, Livermore, California, USA J.R. Harris NPS, Monterey, California, USA
	Funding: Parts of this work were performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The Naval Postgraduate School (NPS), Niowave, Inc., and Boeing have recently demonstrated operation of the first superconducting RF electron gun based on a quarter wave resonator structure. In preliminary tests, this gun has produced 10 ps-long bunches with charge in excess of 78 pC, and with beam energy up to 396 keV. Initial testing occurred at Niowave's Lansing, MI, facility, but the gun and its diagnostic beamline are planned for installation at NPS in the near future. The design of the diagnostic beamline is conducive to the addition of a Cerenkov radiator without interfering with other beamline operations. Design and simulations of a Cerenkov radiator, consisting of a dielectric lined waveguide will be presented. The dispersion relation for the structure is determined and the beam interaction is studied using numerical simulations. The characteristics of the microwave radiation produced in both the long and short bunch regimes will be examined.

Paper

Title

Page

Beam Transport in a Compact Dielectric Wall Accelerator for Proton Therapy

1552

Y.-J. Chen, D.T. Blackfield, G.J. Caporaso, S.D. Nelson, B. R. Poole
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA2A27344.
To attain the highest accelerating gradient in the compact dielectric wall (DWA) accelerator, the accelerating voltage pulses should have the shortest possible duration. To do so, the DWA will be operated in the “virtual” traveling mode*. Since only a short section of HGI wall would be excited, the accelerating field’s axial profile could be non-uniform and time dependent, especially near the entrance and exit of the DWA, which could lead to dispersion in beam acceleration and transport, and eventually emittance growth. The dispersive transverse kick on a short proton bunch at the DWA entrance and its impact on acceptable input proton bunch length will be discussed. Without using any external lenses, the dispersive transverse kicks on the beam can be mitigated. Implementing the mitigations into the transport strategy, we have established a baseline transport case. Results of simulations using 3-D, EM PIC code, LSP** indicate that the DWA transport performance meets the medical specifications for intensity modulation proton treatment. Sensitivity of the transport performance to the switch timing will be presented.
* G. J. Caporaso, Y-J Chen and S. E. Sampayan, "The Dielectric Wall Accelerator", Rev. of Accelerator Science and Technology, vol. 2, p. 253 (2009).
** Alliant Techsystems Inc., http://www.lspsuite.com/.

WEP184

Cerenkov Radiator Driven by a Superconducting RF Electron Gun

1831

B. R. Poole
LLNL, Livermore, California, USA
J.R. Harris
NPS, Monterey, California, USA

Funding: Parts of this work were performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
The Naval Postgraduate School (NPS), Niowave, Inc., and Boeing have recently demonstrated operation of the first superconducting RF electron gun based on a quarter wave resonator structure. In preliminary tests, this gun has produced 10 ps-long bunches with charge in excess of 78 pC, and with beam energy up to 396 keV. Initial testing occurred at Niowave's Lansing, MI, facility, but the gun and its diagnostic beamline are planned for installation at NPS in the near future. The design of the diagnostic beamline is conducive to the addition of a Cerenkov radiator without interfering with other beamline operations. Design and simulations of a Cerenkov radiator, consisting of a dielectric lined waveguide will be presented. The dispersion relation for the structure is determined and the beam interaction is studied using numerical simulations. The characteristics of the microwave radiation produced in both the long and short bunch regimes will be examined.