Analysis of Longitudinal Accelerator Instabilities

Pease, Robert L.

doi:10.1109/tns.1965.4323695

Cited by 3 publications

(3 citation statements)

References 2 publications

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“…The stability of the beam depends upon which side of the curve the point lies. The earliest use of stability diagrams was by Pease [38] for the case of longitudinal stability of unbunched beams. Several papers [39-Fig.…”

Section: Landau Dampingmentioning

confidence: 99%

General mitigation techniques for coherent beam instabilities in particle accelerators

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2021

Eur. Phys. J. Plus

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An important number of coherent beam instability mechanisms can be observed in a particle accelerator, depending if the latter is linear or circular, operated at low, medium or high energy, with a small or a huge amount of turns (for circular machines), close to transition energy or not (below or above), with only one bunch or many bunches, with counter-rotating beams (such as in colliders) or not, if the beam is positively or negatively charged, if one is interested in the longitudinal plane or in the transverse plane, in the presence of linear coupling between the transverse planes or not, in the presence of nonlinearities or not, in the presence of noise or not, etc. Building a realistic impedance model of a machine is a necessary step to be able to evaluate the machine performance limitations, identify the main contributors in case an impedance reduction is required, and study the interaction with other mechanisms such as optics (linear and nonlinear), RF gymnastics, transverse damper, noise, space charge, electron cloud, and beam–beam (in a collider). Better characterising an instability is the first step before trying to find appropriate mitigation measures and push the performance of a particle accelerator, as some mitigation methods are beneficial for some effects and detrimental for some others. For this, an excellent instrumentation is of paramount importance to be able to diagnose if the instability is longitudinal or transverse, single bunch, or coupled bunch, involving only one mode of oscillation or several, and the evolution of the intrabunch motion with intensity is a fundamental observable with high-intensity high-brightness beams. Finally, among the possible mitigation methods of coherent beam instabilities, the ones perturbing the least the single-particle motion (leading to the largest necessary dynamic aperture and beam lifetime) and easiest to implement for day-to-day operation in the machine control room should be preferred.

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Section: Landau Dampingmentioning

confidence: 99%

General mitigation techniques for coherent beam instabilities in particle accelerators

Métral

2021

Eur. Phys. J. Plus

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“…Equation 8 is valid for a square distribution in energy in the beam. For more realistic shapes of the energy distribution, the coefficient of (AEI E) 2 in Equation 8 has to be modified; various shapes have been studied by Pease (18). Landau & Neil (19) have studied the negative-mass instability with particular reference to plasma betatrons and other plasma devices.…”

Section: Coherent Instabilitiesmentioning

confidence: 99%

“…[This result, as pointed out in (20) , is valid in the limit where the conductivity is large, so that the imaginary part of gl is small compared to the real part.] Pease (18,21) considers the dependence of the threshold on the shape of the distribution.…”

Section: Coherent Instabilitiesmentioning

confidence: 99%