IPAC2012 - List of Authors (Vay, J.-L.)

Paper	Title	Page
TUEPPB006	Direct Numerical Modeling of E-Cloud Driven Instability of Three Consecutive Batches in the CERN SPS	1125
	J.-L. Vay, M.A. Furman, M. Venturini LBNL, Berkeley, California, USA
	Funding: Supported by the US-DOE under Contract DE-AC02-05CH11231, the SciDAC program ComPASS and the US-LHC Accelerator Research Program (LARP). Electron clouds impose limitations on current accelerators that may be more severe for future machines, unless adequate measures of mitigation are taken. The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the buildup and interaction of electron clouds with a proton bunch train in the CERN SPS accelerator. Results suggest that a positive feedback mechanism exists between the electron buildup and the e-cloud driven transverse instability, leading to a net increase in predicted electron density. Used resources of NERSC.

WEEPPB003	Modeling of 10 GeV-1 TeV Laser-Plasma Accelerators Using Lorentz Boosted Simulations	2172
	J.-L. Vay, E. Esarey, C.G.R. Geddes, W. Leemans, C.B. Schroeder LBNL, Berkeley, California, USA E. Cormier-Michel Tech-X, Boulder, Colorado, USA D.P. Grote LLNL, Livermore, California, USA
	Funding: Supported by US-DOE Contracts DE-AC02-05CH11231 and DE-AC52-07NA27344, US-LHC program LARP, and US-DOE SciDAC program ComPASS. Modeling of laser-plasma wakefield accelerators in an optimal frame of reference [J.-L. Vay, Phys. Rev. Lett. 98 130405 (2007)] allows direct and efficient full-scale modeling of deeply depleted and beam loaded laser-plasma stages of 10 GeV-1 TeV (parameters not computationally accessible otherwise). This verifies the scaling of plasma accelerators to very high energies and accurately models the laser evolution and the accelerated electron beam transverse dynamics and energy spread. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively. Agreement at the percentage level is demonstrated between simulations using different frames of reference for a 0.1 GeV class stage. Obtaining these speedups and levels of accuracy was permitted by solutions for handling data input (in particular particle and laser beams injection) and output in a relativistically boosted frame of reference, as well as mitigation of a high-frequency instability that otherwise limits effectiveness. Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231.

WEPPP076	Analysis of Numerical Noise in Particle-In-Cell Simulations of Single-Bunch Transverse Instabilities and Feedback in the CERN SPS	2888
	R. Secondo, J.-L. Vay, M. Venturini LBNL, Berkeley, California, USA
	Funding: Work supported by the US-DOE and the US-LHC Accelerator Research Program LARP under Contract DE-AC02-05CH11231. Used resources of NERSC and the Lawrencium cluster at LBNL The operation at high current of the SPS at CERN is limited by transverse Single-Bunch instabilities generated by the effect of electron clouds. A model of a high bandwidth feedback control system has been implemented in the macro-particle code WARP to study bunch dynamics and identify system requirements for the efficient damping of single-bunch transverse instability. We analyze the effect of numerical noise and choice of simulation parameters on the modeling of beam dynamics, focusing in particular on the investigation of the feedback system requirements of minimum power to damp the instability and frequency bandwidth given a fixed gain. We report on simulation results and discuss the plans for the future improvements of the feedback model.

THPPP096	Recent Developments and Applications of the Beam Simulation Code Warp	3957
	J.-L. Vay, P.A. Seidl LBNL, Berkeley, California, USA A. Friedman, D.P. Grote LLNL, Livermore, California, USA
	Funding: Supported by US-DOE Contracts DE-AC02-05CH11231 and DE-AC52-07NA27344. Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231. The Particle-In-Cell Framework Warp is being developed by the Heavy Ion Fusion US program to guide the development of accelerators for high energy density experiments and ultimately for inertial fusion energy. Accurate predictions of the beam phase space are important for understanding the limits to the pulse compression, in particular for NDCX-II now under construction at LBNL. We will present a new numerical method that correct for the effects of linear correlations, offering accurate mapping of energy spread and temperature. The interaction of the beam with the neutralizing plasma can affect non linearly the phase space of the beam. We will present fully kinetic simulation of the beam/plasma interaction aimed toward a better understanding of these effects and possibilities for mitigating or exploiting them. We will also present an application of the original warped coordinate algorithm to the modeling of charge separation in the transition of a 50 MeV singly charged Uranium beam to higher charge state upon passing through a stripping foil, with the goal of decreasing the cost of a Heavy Ion Fusion driver. We also describe studies of beams in plasmas and of injector optimization. Used resources of NERSC.

Paper

Title

Page

Direct Numerical Modeling of E-Cloud Driven Instability of Three Consecutive Batches in the CERN SPS

1125

J.-L. Vay, M.A. Furman, M. Venturini
LBNL, Berkeley, California, USA

Funding: Supported by the US-DOE under Contract DE-AC02-05CH11231, the SciDAC program ComPASS and the US-LHC Accelerator Research Program (LARP).
Electron clouds impose limitations on current accelerators that may be more severe for future machines, unless adequate measures of mitigation are taken. The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the buildup and interaction of electron clouds with a proton bunch train in the CERN SPS accelerator. Results suggest that a positive feedback mechanism exists between the electron buildup and the e-cloud driven transverse instability, leading to a net increase in predicted electron density.
Used resources of NERSC.

WEEPPB003

Modeling of 10 GeV-1 TeV Laser-Plasma Accelerators Using Lorentz Boosted Simulations

2172

J.-L. Vay, E. Esarey, C.G.R. Geddes, W. Leemans, C.B. Schroeder
LBNL, Berkeley, California, USA
E. Cormier-Michel
Tech-X, Boulder, Colorado, USA
D.P. Grote
LLNL, Livermore, California, USA

Funding: Supported by US-DOE Contracts DE-AC02-05CH11231 and DE-AC52-07NA27344, US-LHC program LARP, and US-DOE SciDAC program ComPASS.
Modeling of laser-plasma wakefield accelerators in an optimal frame of reference [J.-L. Vay, Phys. Rev. Lett. 98 130405 (2007)] allows direct and efficient full-scale modeling of deeply depleted and beam loaded laser-plasma stages of 10 GeV-1 TeV (parameters not computationally accessible otherwise). This verifies the scaling of plasma accelerators to very high energies and accurately models the laser evolution and the accelerated electron beam transverse dynamics and energy spread. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively. Agreement at the percentage level is demonstrated between simulations using different frames of reference for a 0.1 GeV class stage. Obtaining these speedups and levels of accuracy was permitted by solutions for handling data input (in particular particle and laser beams injection) and output in a relativistically boosted frame of reference, as well as mitigation of a high-frequency instability that otherwise limits effectiveness.
Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231.

WEPPP076

Analysis of Numerical Noise in Particle-In-Cell Simulations of Single-Bunch Transverse Instabilities and Feedback in the CERN SPS

2888

R. Secondo, J.-L. Vay, M. Venturini
LBNL, Berkeley, California, USA

Funding: Work supported by the US-DOE and the US-LHC Accelerator Research Program LARP under Contract DE-AC02-05CH11231. Used resources of NERSC and the Lawrencium cluster at LBNL
The operation at high current of the SPS at CERN is limited by transverse Single-Bunch instabilities generated by the effect of electron clouds. A model of a high bandwidth feedback control system has been implemented in the macro-particle code WARP to study bunch dynamics and identify system requirements for the efficient damping of single-bunch transverse instability. We analyze the effect of numerical noise and choice of simulation parameters on the modeling of beam dynamics, focusing in particular on the investigation of the feedback system requirements of minimum power to damp the instability and frequency bandwidth given a fixed gain. We report on simulation results and discuss the plans for the future improvements of the feedback model.

THPPP096

Recent Developments and Applications of the Beam Simulation Code Warp

3957

J.-L. Vay, P.A. Seidl
LBNL, Berkeley, California, USA
A. Friedman, D.P. Grote
LLNL, Livermore, California, USA

Funding: Supported by US-DOE Contracts DE-AC02-05CH11231 and DE-AC52-07NA27344. Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231.
The Particle-In-Cell Framework Warp is being developed by the Heavy Ion Fusion US program to guide the development of accelerators for high energy density experiments and ultimately for inertial fusion energy. Accurate predictions of the beam phase space are important for understanding the limits to the pulse compression, in particular for NDCX-II now under construction at LBNL. We will present a new numerical method that correct for the effects of linear correlations, offering accurate mapping of energy spread and temperature. The interaction of the beam with the neutralizing plasma can affect non linearly the phase space of the beam. We will present fully kinetic simulation of the beam/plasma interaction aimed toward a better understanding of these effects and possibilities for mitigating or exploiting them. We will also present an application of the original warped coordinate algorithm to the modeling of charge separation in the transition of a 50 MeV singly charged Uranium beam to higher charge state upon passing through a stripping foil, with the goal of decreasing the cost of a Heavy Ion Fusion driver. We also describe studies of beams in plasmas and of injector optimization.
Used resources of NERSC.