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Title: Application of a new scheme for passing through transition energy to the Fermilab Main Ring and Main Injector

Abstract

In the vicinity of the transition energy of an ion synchrotron the longitudinal oscillation frequency drops and the motion becomes non- adiabatic; the result is emittance dilution. Furthermore, because the synchrotron oscillation is too slow to average particle energy gain, particles off the synchronous phase get to much or too little acceleration depending whether they lead or lag; therefore, momentum spread is increased. In this regime of rf focusing degrades beam quality. Directly J. Griffin has proposed eliminating the rf focusing near transition by flattening the rf waveform with a second or third harmonic component. The rf is phased so that all particles in the bunch are accelerated by the flattened portion, receiving just the acceleration required by the magnet cycle. We will show by concrete examples related to the Fermilab Main Ring (MR) and Main Injector (MI) that one can eliminate rf focusing sufficiently long before and after transition to reduce the maximum momentum spread and emmitance growth significantly. Additionally, the bunch has its maximum phase spread at transition so that the peak current and resulting microwave instability is mitigated, and the bunch above transition becomes a satisfactory match to an accelerating bucket.

Authors:
;
Publication Date:
Research Org.:
Fermi National Accelerator Lab., Batavia, IL (USA)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (USA)
OSTI Identifier:
5740964
Report Number(s):
FNAL/C-91-131; CONF-910505-187
ON: DE91013675
DOE Contract Number:  
AC02-76CH03000
Resource Type:
Conference
Resource Relation:
Conference: 1991 Institute of Electrical and Electronics Engineers (IEEE) particle accelerator conference (PAC), San Francisco, CA (USA), 6-9 May 1991
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM DYNAMICS; INSTABILITY; BEAM INJECTION; BEAM EMITTANCE; BEAM BUNCHING; EQUATIONS OF MOTION; RF SYSTEMS; SPACE CHARGE; SYNCHROTRON OSCILLATIONS; SYNCHROTRONS; ACCELERATORS; CYCLIC ACCELERATORS; DIFFERENTIAL EQUATIONS; EQUATIONS; OSCILLATIONS; PARTIAL DIFFERENTIAL EQUATIONS; 430200* - Particle Accelerators- Beam Dynamics, Field Calculations, & Ion Optics

Citation Formats

MacLachlan, J A, and Griffin, J E. Application of a new scheme for passing through transition energy to the Fermilab Main Ring and Main Injector. United States: N. p., 1991. Web.
MacLachlan, J A, & Griffin, J E. Application of a new scheme for passing through transition energy to the Fermilab Main Ring and Main Injector. United States.
MacLachlan, J A, and Griffin, J E. Tue . "Application of a new scheme for passing through transition energy to the Fermilab Main Ring and Main Injector". United States. https://www.osti.gov/servlets/purl/5740964.
@article{osti_5740964,
title = {Application of a new scheme for passing through transition energy to the Fermilab Main Ring and Main Injector},
author = {MacLachlan, J A and Griffin, J E},
abstractNote = {In the vicinity of the transition energy of an ion synchrotron the longitudinal oscillation frequency drops and the motion becomes non- adiabatic; the result is emittance dilution. Furthermore, because the synchrotron oscillation is too slow to average particle energy gain, particles off the synchronous phase get to much or too little acceleration depending whether they lead or lag; therefore, momentum spread is increased. In this regime of rf focusing degrades beam quality. Directly J. Griffin has proposed eliminating the rf focusing near transition by flattening the rf waveform with a second or third harmonic component. The rf is phased so that all particles in the bunch are accelerated by the flattened portion, receiving just the acceleration required by the magnet cycle. We will show by concrete examples related to the Fermilab Main Ring (MR) and Main Injector (MI) that one can eliminate rf focusing sufficiently long before and after transition to reduce the maximum momentum spread and emmitance growth significantly. Additionally, the bunch has its maximum phase spread at transition so that the peak current and resulting microwave instability is mitigated, and the bunch above transition becomes a satisfactory match to an accelerating bucket.},
doi = {},
url = {https://www.osti.gov/biblio/5740964}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1991},
month = {1}
}

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