Realistic modeling of microwave instability effects on the evolution of the beam energy-phase distribution in proton synchrotrons
Either bunched or coasting beam in a synchrotron may exhibit microwave instability of the momentum spread is small. A useful physical picture is that beam particles are captured in buckets generated by the beam image current flowing in the longitudinal coupling impedance. Qualitatively, trapping and auto-deceleration occur when the height of the buckets exceed the FWHM energy spread of the beam. Microwave instability implies in addition that the coupling impedance is largest at several times the rf frequency and that the decay of the wakefield is fast enough that bunches do not affect each other. The parameters used in this paper are influenced by the Fermilab Main Ring and design of the Main Injector. The numerical modeling uses standard features of the code ESME. In most of the reported simulations 2 {center dot} 10{sup 4} macroparticles and 32 values of n separated by 1113 provide the current spectrum. Microwave instability may be an intensity limitation during parts of the acceleration cycle where the beam is debunched or loosely bunched, perhaps at injection or high duty factor extraction. Probably of more general importance is the time near transition when the spread in circulation frequency is sharply reduced, i.e., when {eta} {approx} 0. Concrete examples are given in this report.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- AC02-76CH03000
- OSTI ID:
- 5529180
- Report Number(s):
- FNAL/C-91/132; CONF-910505-289; ON: DE91014147; TRN: 91-018765
- 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
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BEAM BUNCHING
INSTABILITY
SYNCHROTRONS
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MICROWAVE RADIATION
PROTON BEAMS
RF SYSTEMS
ACCELERATORS
BEAM DYNAMICS
BEAMS
CYCLIC ACCELERATORS
ELECTROMAGNETIC RADIATION
NUCLEON BEAMS
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430200* - Particle Accelerators- Beam Dynamics
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