2011 Particle Accelerator Conference - List of Authors (Furman, M.A.)

Paper	Title	Page
MOP214	Methods for Quantitative Interpretation of Retarding Field Analyzer Data	501
	J.R. Calvey, J.A. Crittenden, G. Dugan, M.A. Palmer CLASSE, Ithaca, New York, USA M.A. Furman LBNL, Berkeley, California, USA K.C. Harkay ANL, Argonne, USA
	Funding: US Department of Energy grant DE-FC02-08ER41538 US National Science Foundation grant PHY-0734867 Over the course of the CesrTA program at Cornell, over 30 Retarding Field Analyzers (RFAs) have been installed in the CESR storage ring, and a great deal of data has been taken with them. These devices measure the local electron cloud density and energy distribution, and can be used to evaluate the efficacy of different cloud mitigation techniques. Obtaining a quantitative understanding of RFA data requires use of cloud simulation programs, as well as a detailed model of the detector itself. In a drift region, the RFA can be modeled by postprocessing the output of a simulation code, and one can obtain best fit values for important simulation parameters with a chi-square minimization method.

WEP108	Application of Coherent Tune Shift Measurements to the Characterization of Electron Cloud Growth	1680
	D.L. Kreinick, J.A. Crittenden, G. Dugan, M.A. Palmer, G. Ramirez CLASSE, Ithaca, New York, USA M.A. Furman, M. Venturini LBNL, Berkeley, California, USA R. Holtzapple, M. Randazzo CalPoly, San Luis Obispo, California, USA
	Funding: DOE = DE-FC02-08ER41538 NSF = PHY-0734867 Measurements of coherent tune shifts at the Cornell Electron Storage Ring Test Accelerator (CesrTA) have been made for electron and positron beams under a wide variety of beam energies, bunch charge, and bunch train configurations. Comparing the observed tunes with the predictions of several electron cloud simulation programs allows the evaluation of important parameters in these models. These simulations will be used to predict the behavior of the electron cloud in damping rings for future linear colliders. We outline recent improvements to the analysis techniques that should improve the fidelity of the modeling.

WEP154	Direct Numerical Modeling of E-Cloud Driven Instability of a Bunch Train in the CERN SPS	1776
	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). Used resources of NERSC and the Lawrencium cluster at LBNL. Electron clouds impose limitations on current accelerators that may be more severe for future machines, unless adequate measures of mitigation are taken. It has been proposed recently to use feedback systems operating in the GHz range to damp single-bunch transverse coherent electron cloud driven instabilities that may occur in relatively long, ns scale, proton bunches such as those in the CERN SPS. 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 growth rate and frequency patterns in space-time of the electron cloud driven transverse instability for a proton bunch train in the CERN SPS accelerator with, or without, feedback models (with various levels of idealization) for damping the instability. We will present our latest simulation results, contrast them with actual measurements and discuss the implications for the design of the actual feedback system.

Paper

Title

Page

Methods for Quantitative Interpretation of Retarding Field Analyzer Data

501

J.R. Calvey, J.A. Crittenden, G. Dugan, M.A. Palmer
CLASSE, Ithaca, New York, USA
M.A. Furman
LBNL, Berkeley, California, USA
K.C. Harkay
ANL, Argonne, USA

Funding: US Department of Energy grant DE-FC02-08ER41538 US National Science Foundation grant PHY-0734867
Over the course of the CesrTA program at Cornell, over 30 Retarding Field Analyzers (RFAs) have been installed in the CESR storage ring, and a great deal of data has been taken with them. These devices measure the local electron cloud density and energy distribution, and can be used to evaluate the efficacy of different cloud mitigation techniques. Obtaining a quantitative understanding of RFA data requires use of cloud simulation programs, as well as a detailed model of the detector itself. In a drift region, the RFA can be modeled by postprocessing the output of a simulation code, and one can obtain best fit values for important simulation parameters with a chi-square minimization method.

WEP108

Application of Coherent Tune Shift Measurements to the Characterization of Electron Cloud Growth

1680

D.L. Kreinick, J.A. Crittenden, G. Dugan, M.A. Palmer, G. Ramirez
CLASSE, Ithaca, New York, USA
M.A. Furman, M. Venturini
LBNL, Berkeley, California, USA
R. Holtzapple, M. Randazzo
CalPoly, San Luis Obispo, California, USA

Funding: DOE = DE-FC02-08ER41538 NSF = PHY-0734867
Measurements of coherent tune shifts at the Cornell Electron Storage Ring Test Accelerator (CesrTA) have been made for electron and positron beams under a wide variety of beam energies, bunch charge, and bunch train configurations. Comparing the observed tunes with the predictions of several electron cloud simulation programs allows the evaluation of important parameters in these models. These simulations will be used to predict the behavior of the electron cloud in damping rings for future linear colliders. We outline recent improvements to the analysis techniques that should improve the fidelity of the modeling.

WEP154

Direct Numerical Modeling of E-Cloud Driven Instability of a Bunch Train in the CERN SPS

1776

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). Used resources of NERSC and the Lawrencium cluster at LBNL.
Electron clouds impose limitations on current accelerators that may be more severe for future machines, unless adequate measures of mitigation are taken. It has been proposed recently to use feedback systems operating in the GHz range to damp single-bunch transverse coherent electron cloud driven instabilities that may occur in relatively long, ns scale, proton bunches such as those in the CERN SPS. 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 growth rate and frequency patterns in space-time of the electron cloud driven transverse instability for a proton bunch train in the CERN SPS accelerator with, or without, feedback models (with various levels of idealization) for damping the instability. We will present our latest simulation results, contrast them with actual measurements and discuss the implications for the design of the actual feedback system.