Observations of a fast transverse instability in the PSR

Neuffer, D.; Colton, E.; Fitzgerald, D.; Hardek, T.; Hutson, R. L.; Macek, R.; Plum, Michael; Thiessen, H. A.; Wang, T.-S.

doi:10.1016/0168-9002(92)90371-a

Cited by 82 publications

(16 citation statements)

References 2 publications

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“…Electron cloud has been observed in many facilities (including, for example, PEP-II [3], CERN SPS [4], KEKB [5], ANL APS [6], FNAL Main Injector [7], LANL PSR [8], and the LHC [9]), and is expected to be a major limiting factor in next generation positron and proton storage rings. It is of particular concern in the damping rings of electron-positron colliders, which will produce a large amount of synchrotron radiation and require very small emittances [10].…”

Section: Introductionmentioning

confidence: 99%

Comparison of electron cloud mitigating coatings using retarding field analyzers

Calvey

Hartung

et al. 2014

Nuclear Instruments and Methods in Physics Research Section A:

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In 2008, the Cornell Electron Storage Ring (CESR) was reconfigured to serve as a test accelerator (CESRTA) for next generation lepton colliders, in particular for the ILC damping ring. A significant part of this program has been the installation of diagnostic devices to measure and quantify the electron cloud effect, a potential limiting factor in these machines. One such device is the Retarding Field Analyzer (RFA), which provides information on the local electron cloud density and energy distribution. Several different styles of RFAs have been designed, tested, and deployed throughout the CESR ring. They have been used to study the growth of the cloud in different beam conditions, and to evaluate the efficacy of different mitigation techniques. This paper will provide an overview of RFA results obtained in a magnetic field free environment.

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Section: Introductionmentioning

confidence: 99%

Comparison of electron cloud mitigating coatings using retarding field analyzers

Calvey

Hartung

et al. 2014

Nuclear Instruments and Methods in Physics Research Section A:

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“…A great deal of evidence indicates that the primary instability that limits the performance of the PSR is a twostream electron-proton (e-p) instability [1,2]. This instability is manifested in coupled coherent vertical oscillations of the proton beam and the electron cloud that is present in the vacuum chamber and confined by the electric potential of the proton beam.…”

Section: Introductionmentioning

confidence: 99%

Active damping of the E-P instability at the LANL PSR

McCrady

Macek

Zaugg

et al. 2007

2007 IEEE Particle Accelerator Conference (PAC)

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A prototype of an analog, transverse (vertical) feedback system for active damping of the two-stream (e-p) instability has been developed and successfully tested at the Los Alamos National Laboratory Proton Storage Ring (PSR). This system was able to improve the instability threshold by approximately 30% (as measured by the change in RF buncher voltage at instability threshold). Evidence obtained from these tests suggests that further improvement in performance is limited by beam leakage into the gap at lower RF buncher voltage and the onset of instability in the horizontal plane, which had no feedback. Here we describe the present system configuration, system optimization, results of several recent experimental tests, and results from studies of factors limiting its performance.

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“…For example, a background population of electrons can result by secondary emission when energetic particles strike the chamber wall, or through ionization of background neutral gas by the beam ions. When a second charge component is present, it has been recognized for many years, both in theoretical studies and in experimental observations [10][11][12][13][14][15][16][17][18][19][20][21] , that the relative streaming motion of the high-intensity beam particles through the background charge species provides the free energy to drive the classical two-stream instability, appropriately modified to include the effects of dc space charge, relativistic kinematics, transverse beam dynamics, presence of a conducting wall, etc. A well-documented example is the electron-proton (e-p) instability observed in the Proton Storage Ring [16][17][18] , although a similar instability also exists for other ion species, including (for example) electron-ion interactions in electron storage rings [19][20][21] .…”

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confidence: 99%

Effects on axial momentum spread on the electron-ion two-stream instability in high-intensity ion beams

Davidso¹,

Qin²

2000

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Use is made of the Vlasov-Maxwell equations to describe the electron-ion two-stream instability driven by the directed axial motion of a high-intensity ion beam propagating through a stationary population of (unwanted) background electrons. The ion beam is treated as continuous in the z-direction, and the electrons are electrostatically confined in the transverse direction by the space-charge potential produced by the excess ion charge. The analysis is carried out for arbitrary beam intensity, consistent with transverse confinement of the beam particles, and arbitrary fractional charge neutralization by the background electrons. For the case of overlapping step-function ion and electron density profiles, corresponding to monoenergetic electrons and ions in the transverse direction, detailed stability properties are calculated, including the important effects of an axial momentum spread, over a wide range of system parameters for dipole perturbations with azimuthal mode number = 1. The two-stream instability growth rate is found to increase with increasing beam intensity, increasing fractional charge neutralization, and decreasing proximity of the conducting wall. It is shown that Landau damping associated with a modest axial momentum spread of the beam ions and background electrons has a strong stabilizing influence on the instability.

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Observations of a fast transverse instability in the PSR

Cited by 82 publications

References 2 publications

Comparison of electron cloud mitigating coatings using retarding field analyzers

Comparison of electron cloud mitigating coatings using retarding field analyzers

Active damping of the E-P instability at the LANL PSR

Effects on axial momentum spread on the electron-ion two-stream instability in high-intensity ion beams

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