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Title: High-Precision Resonant Cavity Beam Position, Emittance And Third-Moment Monitors

Abstract

Linear colliders and FEL facilities need fast, nondestructive beam position and profile monitors to facilitate machine tune-up, and for use with feedback control. FAR-TECH, Inc., in collaboration with SLAC, is developing a resonant cavity diagnostic to simultaneously measure the dipole, quadrupole and sextupole moments of the beam distribution. Measurements of dipole and quadrupole moments at multiple locations yield information about beam orbit and emittance. The sextupole moment can reveal information about beam asymmetry which is useful in diagnosing beam tail deflections caused by short-range dipole wakefields. In addition to the resonance enhancement of a single-cell cavity, use of a multi-cell standing-wave structure further enhances signal strength and improves the resolution of the device. An estimated resolution is better than 1 {micro}m in rms beam size and better than 1 nm in beam position.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
877442
Report Number(s):
SLAC-PUB-11758
TRN: US0601473
DOE Contract Number:
AC02-76SF00515
Resource Type:
Conference
Resource Relation:
Conference: Prepared for Particle Accelerator Conference (PAC 05), Knoxville, Tennessee, 16-20 May 2005
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACCELERATORS; ASYMMETRY; BEAM POSITION; DIPOLES; DISTRIBUTION; FEEDBACK; LINEAR COLLIDERS; MONITORS; QUADRUPOLE MOMENTS; QUADRUPOLES; RESOLUTION; RESONANCE; STANFORD LINEAR ACCELERATOR CENTER; Accelerators,ACCPHY

Citation Formats

Barov, N., Kim, J.S., Weidemann, A.W., /FARTECH, San Diego, Miller, R.H., Nantista, C.D., and /SLAC. High-Precision Resonant Cavity Beam Position, Emittance And Third-Moment Monitors. United States: N. p., 2006. Web.
Barov, N., Kim, J.S., Weidemann, A.W., /FARTECH, San Diego, Miller, R.H., Nantista, C.D., & /SLAC. High-Precision Resonant Cavity Beam Position, Emittance And Third-Moment Monitors. United States.
Barov, N., Kim, J.S., Weidemann, A.W., /FARTECH, San Diego, Miller, R.H., Nantista, C.D., and /SLAC. Tue . "High-Precision Resonant Cavity Beam Position, Emittance And Third-Moment Monitors". United States. doi:. https://www.osti.gov/servlets/purl/877442.
@article{osti_877442,
title = {High-Precision Resonant Cavity Beam Position, Emittance And Third-Moment Monitors},
author = {Barov, N. and Kim, J.S. and Weidemann, A.W. and /FARTECH, San Diego and Miller, R.H. and Nantista, C.D. and /SLAC},
abstractNote = {Linear colliders and FEL facilities need fast, nondestructive beam position and profile monitors to facilitate machine tune-up, and for use with feedback control. FAR-TECH, Inc., in collaboration with SLAC, is developing a resonant cavity diagnostic to simultaneously measure the dipole, quadrupole and sextupole moments of the beam distribution. Measurements of dipole and quadrupole moments at multiple locations yield information about beam orbit and emittance. The sextupole moment can reveal information about beam asymmetry which is useful in diagnosing beam tail deflections caused by short-range dipole wakefields. In addition to the resonance enhancement of a single-cell cavity, use of a multi-cell standing-wave structure further enhances signal strength and improves the resolution of the device. An estimated resolution is better than 1 {micro}m in rms beam size and better than 1 nm in beam position.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Mar 14 00:00:00 EST 2006},
month = {Tue Mar 14 00:00:00 EST 2006}
}

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  • The Sub-picosecond Accelerator at Los Alamos National Laboratory is a 1300 MHz, 8 MeV photoinjector. Concerned mainly with the exploration of bunched electron beams, the Sub-picosecond Accelerator facility is also used for a variety of other research. One ongoing task is the exploitation of the second moment properties of beam position monitor signals to measure the rms emittance. The unique properties of photoinjector beams make Gaussian assumptions about their distribution inaccurate and traditional methods of measuring the rms emittance fail. Using beam position monitors to measure the emittance, however, requires no beam distribution assumptions. Presented here are the first emittancemore » measurements with this method on the Sub-picosecond Accelerator.« less
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  • A high precision emittance measurement requires precise beam position at the measurement location. At present there is no existing technique, commercial or otherwise, for non-destructive pulse-to-pulse simultaneous beam position and emittance measurement. FARTECH, Inc. is currently developing a high precision cavity-based beam monitor for simultaneous beam position and emittance measurements pulse-to-pulse, without beam interception and without moving parts. The design and analysis of a multi-cavity standing wave structure for a pulse-to-pulse emittance measurement system in which the quadrupole and the dipole standing wave modes resonate at harmonics of the beam operating frequency is presented. Considering the Next Linear Collider beams,more » an optimized 9-cavity standing wave system is designed for simultaneous high precision beam position and emittance measurements. It operates with the {pi}-quadrupole mode resonating at 16th harmonic of the NLC bunch frequency, and the 3 {pi}/4 dipole mode at 12th harmonic (8.568 GHz). The 9-cavity system design indicates that the two dipoles resonate almost at the same frequency 8.583 GHz and the quadrupole at 11.427 GHz according to the scattering parameter calculations. The design can be trivially scaled so that the dipole frequency is at 8.568 GHz, and the quadrupole frequency can then be tuned during fabrication to achieve the desired 11.424 GHz. The output powers from these modes are estimated for the NLC beams. An estimated rms-beam size resolution is sub micro-meters and beam positions in sub nano-meters.« less