IPAC2012 - List of Authors (Stoltz, P.)

Paper

Title

Page

Parallel 3D Simulations to Support Commissioning of a Solenoid-based LEBT Test Stand

349

B.T. Schwartz, D.T. Abell, D.L. Bruhwiler, Y. Choi, S. Mahalingam, P. Stoltz, J. von Stecher
Tech-X, Boulder, Colorado, USA
B. Han, M.P. Stockli
ORNL, Oak Ridge, Tennessee, USA

Funding: This work is supported by the US DOE Office of Science, Office of Basic Energy Sciences, including grant No. DE-SC0000844.
A solenoid-based low-energy beam transport (LEBT) test stand is under development for the Spallation Neutron Source (SNS). To support commissioning of the test stand, the parallel Vorpal framework is being used for 3D electrostatic particle-in-cell (PIC) simulations of H⁻ beam dynamics in the LEBT, including impact ionization physics and MHz chopping of the partially-neutralized \Hm beam. Here we describe the process of creating a partially-neutralized beam and examine the effects of a single chopping event on the beam's emittance.

TUOAA01

3-Dimensional Modeling of Electron Clouds in Non-uniform Magnetic Fields

1059

S.A. Veitzer, P. Stoltz
Tech-X, Boulder, Colorado, USA
J.A. Crittenden, K.G. Sonnad
CLASSE, Ithaca, New York, USA

Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499) and by the National Science Foundation Grant PHY-0734867.
Electron clouds have the potential to pose serious limitations on accelerator performance in both hadron and lepton beams. Experiments using rf diagnostics are being performed to measure electron cloud densities at a number of accelerator facilities. However, it is difficult to calibrate plasma density with signal strength in these experiments, and modeling involves a number of technical and numerical challenges. Typically 2-Dimensional electrostatic methods have been used to model cloud buildup under beam crossing conditions. However, since traveling-wave rf experiments typically occur over many meters of beam pipe where magnetic fields are changing, one needs to develop 3-Dimensional electromagnetic models in order to accurately simulate rf diagnostics. We have developed accurate models of electron cloud-induced phase shifts in rf in a system with spatially varying magnetic field configurations using the plasma simulation code VORPAL. We present here results for measuring phase shifts in the CESR wiggler with realistic, spatially non-uniform magnetic field configurations.

Slides TUOAA01 [18.367 MB]

WEEPPB001

Progress Toward a High-Transformer-Ratio Dielectric Wakefield Experiment at FLASH

2166

F. Lemery, D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J. Osterhoff
MPQ, Garching, Munich, Germany
C.A.J. Palmer
DESY, Hamburg, Germany
P. Stoltz
Tech-X, Boulder, Colorado, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
Dielectric wakefield accelerators offer many advantages over conventional RF accelerators such as higher acceleration gradients and cost effectiveness. In this paper we describe our experimental plans to demonstrate enhanced transformer ratios with drive and witness bunches. The experiment, will be performed at the Free-electron LASer in Hamburg (FLASH) and utilizes unique pulse shaping capabilities using the dual-frequency superconducting linac to produce high transformer ratios (>2). The beam-driven acceleration mechanism will be based on a cylindrical-symmetric dielectric-lined waveguide (DLW). The experimental setup is described, and start-to-end numerical simulations of the experiment will be presented.

Paper	Title	Page
MOPPC091	Parallel 3D Simulations to Support Commissioning of a Solenoid-based LEBT Test Stand	349
	B.T. Schwartz, D.T. Abell, D.L. Bruhwiler, Y. Choi, S. Mahalingam, P. Stoltz, J. von Stecher Tech-X, Boulder, Colorado, USA B. Han, M.P. Stockli ORNL, Oak Ridge, Tennessee, USA
	Funding: This work is supported by the US DOE Office of Science, Office of Basic Energy Sciences, including grant No. DE-SC0000844. A solenoid-based low-energy beam transport (LEBT) test stand is under development for the Spallation Neutron Source (SNS). To support commissioning of the test stand, the parallel Vorpal framework is being used for 3D electrostatic particle-in-cell (PIC) simulations of H⁻ beam dynamics in the LEBT, including impact ionization physics and MHz chopping of the partially-neutralized \Hm beam. Here we describe the process of creating a partially-neutralized beam and examine the effects of a single chopping event on the beam's emittance.

TUOAA01	3-Dimensional Modeling of Electron Clouds in Non-uniform Magnetic Fields	1059
	S.A. Veitzer, P. Stoltz Tech-X, Boulder, Colorado, USA J.A. Crittenden, K.G. Sonnad CLASSE, Ithaca, New York, USA
	Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499) and by the National Science Foundation Grant PHY-0734867. Electron clouds have the potential to pose serious limitations on accelerator performance in both hadron and lepton beams. Experiments using rf diagnostics are being performed to measure electron cloud densities at a number of accelerator facilities. However, it is difficult to calibrate plasma density with signal strength in these experiments, and modeling involves a number of technical and numerical challenges. Typically 2-Dimensional electrostatic methods have been used to model cloud buildup under beam crossing conditions. However, since traveling-wave rf experiments typically occur over many meters of beam pipe where magnetic fields are changing, one needs to develop 3-Dimensional electromagnetic models in order to accurately simulate rf diagnostics. We have developed accurate models of electron cloud-induced phase shifts in rf in a system with spatially varying magnetic field configurations using the plasma simulation code VORPAL. We present here results for measuring phase shifts in the CESR wiggler with realistic, spatially non-uniform magnetic field configurations.
	Slides TUOAA01 [18.367 MB]

WEEPPB001	Progress Toward a High-Transformer-Ratio Dielectric Wakefield Experiment at FLASH	2166
	F. Lemery, D. Mihalcea, P. Piot Northern Illinois University, DeKalb, Illinois, USA J. Osterhoff MPQ, Garching, Munich, Germany C.A.J. Palmer DESY, Hamburg, Germany P. Stoltz Tech-X, Boulder, Colorado, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 Dielectric wakefield accelerators offer many advantages over conventional RF accelerators such as higher acceleration gradients and cost effectiveness. In this paper we describe our experimental plans to demonstrate enhanced transformer ratios with drive and witness bunches. The experiment, will be performed at the Free-electron LASer in Hamburg (FLASH) and utilizes unique pulse shaping capabilities using the dual-frequency superconducting linac to produce high transformer ratios (>2). The beam-driven acceleration mechanism will be based on a cylindrical-symmetric dielectric-lined waveguide (DLW). The experimental setup is described, and start-to-end numerical simulations of the experiment will be presented.