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Title: Exact cancellation of emittance growth due to coupled transverse dynamics in solenoids and rf couplers

Abstract

Weak, rotated magnetic and radio frequency quadrupole fields in electron guns and injectors can couple the beam’s horizontal with vertical motion, introduce correlations between otherwise orthogonal transverse momenta, and reduce the beam brightness. This paper discusses two important sources of coupled transverse dynamics common to most electron injectors. The first is quadrupole focusing followed by beam rotation in a solenoid, and the second coupling comes from a skewed high-power rf coupler or cavity port which has a rotated rf quadrupole field. It is shown that a dc quadrupole field can correct for both types of couplings and exactly cancel their emittance growths. The degree of cancellation of the rf skew quadrupole emittance is limited by the electron bunch length. Analytic expressions are derived and compared with emittance simulations and measurements.

Authors:
; ;
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1417222
Alternate Identifier(s):
OSTI ID: 1424742
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Published Article
Journal Name:
Physical Review Accelerators and Beams
Additional Journal Information:
Journal Name: Physical Review Accelerators and Beams Journal Volume: 21 Journal Issue: 1; Journal ID: ISSN 2469-9888
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS

Citation Formats

Dowell, David H., Zhou, Feng, and Schmerge, John. Exact cancellation of emittance growth due to coupled transverse dynamics in solenoids and rf couplers. United States: N. p., 2018. Web. doi:10.1103/PhysRevAccelBeams.21.010101.
Dowell, David H., Zhou, Feng, & Schmerge, John. Exact cancellation of emittance growth due to coupled transverse dynamics in solenoids and rf couplers. United States. doi:10.1103/PhysRevAccelBeams.21.010101.
Dowell, David H., Zhou, Feng, and Schmerge, John. Wed . "Exact cancellation of emittance growth due to coupled transverse dynamics in solenoids and rf couplers". United States. doi:10.1103/PhysRevAccelBeams.21.010101.
@article{osti_1417222,
title = {Exact cancellation of emittance growth due to coupled transverse dynamics in solenoids and rf couplers},
author = {Dowell, David H. and Zhou, Feng and Schmerge, John},
abstractNote = {Weak, rotated magnetic and radio frequency quadrupole fields in electron guns and injectors can couple the beam’s horizontal with vertical motion, introduce correlations between otherwise orthogonal transverse momenta, and reduce the beam brightness. This paper discusses two important sources of coupled transverse dynamics common to most electron injectors. The first is quadrupole focusing followed by beam rotation in a solenoid, and the second coupling comes from a skewed high-power rf coupler or cavity port which has a rotated rf quadrupole field. It is shown that a dc quadrupole field can correct for both types of couplings and exactly cancel their emittance growths. The degree of cancellation of the rf skew quadrupole emittance is limited by the electron bunch length. Analytic expressions are derived and compared with emittance simulations and measurements.},
doi = {10.1103/PhysRevAccelBeams.21.010101},
journal = {Physical Review Accelerators and Beams},
number = 1,
volume = 21,
place = {United States},
year = {2018},
month = {1}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1103/PhysRevAccelBeams.21.010101

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Cited by: 2 works
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