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Title: Simulation and Analysis of Microwave Transmission through an Electron Cloud, a Comparison of Results

Abstract

Simulation studies for transmission of microwaves through electron cloudes show good agreement with analytic results. The elctron cloud produces a shift in phase of the microwave. Experimental observation of this phenomena would lead to a useful diagnostic tool for acessing the local density of electron clouds in an accelerator. These experiments are being carried out at the CERN SPS and the PEP-II LER at SLAC and is proposed to be done at the Fermilab maininjector. In this study, a brief analysis of the phase shift is provided and the results are compared with that obtained from simulations.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
Accelerator& Fusion Research Division
OSTI Identifier:
936734
Report Number(s):
LBNL-870E
TRN: US0805686
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Conference
Resource Relation:
Conference: 22nd Particle Accelerator Conference, Albuquerque, New Mexico, June 25-29, 2007
Country of Publication:
United States
Language:
English
Subject:
43; ACCELERATORS; CERN; CLOUDS; ELECTRONS; FERMILAB; PHASE SHIFT; SIMULATION; STANFORD LINEAR ACCELERATOR CENTER

Citation Formats

Sonnad, Kiran, Sonnad, Kiran, Furman, Miguel, Veitzer, Seth, Stoltz, Peter, and Cary, John. Simulation and Analysis of Microwave Transmission through an Electron Cloud, a Comparison of Results. United States: N. p., 2007. Web.
Sonnad, Kiran, Sonnad, Kiran, Furman, Miguel, Veitzer, Seth, Stoltz, Peter, & Cary, John. Simulation and Analysis of Microwave Transmission through an Electron Cloud, a Comparison of Results. United States.
Sonnad, Kiran, Sonnad, Kiran, Furman, Miguel, Veitzer, Seth, Stoltz, Peter, and Cary, John. Mon . "Simulation and Analysis of Microwave Transmission through an Electron Cloud, a Comparison of Results". United States. doi:. https://www.osti.gov/servlets/purl/936734.
@article{osti_936734,
title = {Simulation and Analysis of Microwave Transmission through an Electron Cloud, a Comparison of Results},
author = {Sonnad, Kiran and Sonnad, Kiran and Furman, Miguel and Veitzer, Seth and Stoltz, Peter and Cary, John},
abstractNote = {Simulation studies for transmission of microwaves through electron cloudes show good agreement with analytic results. The elctron cloud produces a shift in phase of the microwave. Experimental observation of this phenomena would lead to a useful diagnostic tool for acessing the local density of electron clouds in an accelerator. These experiments are being carried out at the CERN SPS and the PEP-II LER at SLAC and is proposed to be done at the Fermilab maininjector. In this study, a brief analysis of the phase shift is provided and the results are compared with that obtained from simulations.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Mar 12 00:00:00 EDT 2007},
month = {Mon Mar 12 00:00:00 EDT 2007}
}

Conference:
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  • Simulation studies for transmission of microwaves through electron clouds show good agreement with analytic results. The electron cloud produces a shift in phase of the microwave. Experimental observation of this phenomena would lead to a useful diagnostic tool for accessing the local density of electron clouds in an accelerator. These experiments are being carried out at the CERN SPS and the PEP-II LER at SLAC and is proposed to be done at the Fermilab main injector. In this study, a brief analysis of the phase shift is provided and the results are compared with that obtained from simulations.
  • The electromagnetic particle-in-cell (PIC) code VORPAL is being used to simulate the interaction of microwave radiation through an electron cloud. The results so far showgood agreement with theory for simple cases. The study has been motivated by previous experimental work on this problem at the CERN SPS [1], experiments at the PEP-II Low Energy Ring (LER) at SLAC [4], and proposed experiments at the Fermilab Main Injector (MI). With experimental observation of quantities such as amplitude, phase and spectrum of the output microwave radiation and with support from simulations for different cloud densities and applied magnetic fields, this technique canmore » prove to be a useful probe for assessing the presence as well as the densityof electron clouds.« less
  • Simulations of the microwave transmission properties through the electron cloud at the Fermilab Main Injector have been implemented using the plasma simulation code 'VORPAL'. Phase shifts and attenuation curves have been calculated for the lowest frequency TE mode, slightly above the cutoff frequency, in field free regions, in the dipoles and quadrupoles. Preliminary comparisons with experimental results for the dipole case are showed and will guide the next generation of experiments.
  • Triggered by the experimental results of the MINIX, a computer simulation study was initiated on the nonlinear excitation of electrostatic electron cyclotron waves by a monochromatic electromagnetic wave such as the transmitted microwave in the MINIX. The model used assumes that both of the excited waves and exciting (pumping) electromagnetic wave as well as the idler electromagnetic wave propagate in the direction perpendicular to the external magnetic field. The simulation code used for this study was the one-and-two-half dimensional electromagnetic particle code named KEMPO. The simulation result shows the high power electromagnetic wave produces both the backscattered electromagnetic wave andmore » electrostatic electron cyclotron waves as a result of nonlinear parametric instability. Detailed nonlinear microphysics related to the wave excitation is discussed in terms of the nonlinear wave-wave couplings and associated ponderomotive force produced by the high power electromagnetic waves. 2 references, 4 figures.« less
  • Clouds of electrons in the vacuum chambers of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of the size of these accelerators, it is difficult to probe the low energy electron clouds over substantial lengths of the beam pipe. We applied a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave which is independently excited and transmitted over a straight section of the accelerator. The modulation in the wave transmission which appear to increase in depth when the clearing solenoidsmore » are switched off, seem to be directly correlated to the electron cloud density in the section. Furthermore, we expect a larger phase shift of a wave transmitted through magnetic dipole field regions if the transmitted wave couples with the gyration motion of the electrons. We have used this technique to measure the average electron cloud density (ECD) specifically for the first time in magnetic field regions of a new 4-dipole chicane in the positron ring of the PEP-II collider at SLAC. In this paper we present and discuss the measurements taken in the Low Energy Ring (LER) between 2006 and 2008.« less