Possible Emittance Increase through Filamentation Due to Space Charge in Continuous Beams

Lapostolle, P.

doi:10.1109/tns.1971.4326292

Cited by 198 publications

(93 citation statements)

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“…It was shown by Lapostolle et al [18] and Sacherer et al [16] that for ellipsoidal bunches, where the RMS emittance is either constant or specified in advance, evolution of the RMS beam projections are nearly independent of the density profile. This means that, for the calculation of the RMS dynamics, the actual distribution can be replaced by an equivalent uniform beam, which has the same RMS values.…”

Section: A Coupled Envelope Equations In Ellipsoidal Geometrymentioning

confidence: 99%

Space charge modeling of dense electron beams with large energy spreads

Fubiani

Qiang

Esarey

et al. 2006

Phys. Rev. ST Accel. Beams

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Theoretical and numerical studies of the transport in vacuum of multi-nC, multi-MeV electron beams are performed using several methods, including envelope models, a novel semianalytic approach using ellipsoidal shell decomposition, a modified electrostatic particle-in-cell method, and a point-to-point interaction model. The effects of space-charge forces on the longitudinal and transverse bunch properties are evaluated for various bunch lengths, energies, energy spreads, and charges. An evaluation of the various methods for studying space-charge effects in large energy spread, high charge beams is summarized. Examples are given for beam distributions typical of those generated by plasma-based accelerators. It is found that, for the highly correlated beams produced in the self-modulated regime, the high energy portion of the beam can gain significant energy while propagating in vacuum due to spacecharge effects.

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Section: A Coupled Envelope Equations In Ellipsoidal Geometrymentioning

confidence: 99%

Space charge modeling of dense electron beams with large energy spreads

Fubiani

Qiang

Esarey

et al. 2006

Phys. Rev. ST Accel. Beams

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“…Until recently, it was believed that only one matched solution is present for a given set of beam and focusing parameters and that this solution becomes unstable as the focusing field intensity is raised above a certain threshold. 2,[7][8][9] The threshold corresponds to a vacuumphase advance of 90°. By vacuum-phase advance we mean the angle that a particle would rotate per focusing period in the presence of the external field but in the abscence of space-charge, and is used here as a measure of the focusing magnetic field strength.…”

Section: Introductionmentioning

confidence: 99%

The role of the focusing field profile on the stability of periodically focused particle beams

2003

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Magnetic compound refractive lens for focusing and polarizing cold neutron beams Rev. Sci. Instrum. 78, 035101 (2007) The role of the focusing field profile on the stability of periodically focused particle beams In this paper, the role of the focusing field profile on the stability of periodically focused particle beams is investigated, paying special attention to the transport within the new regions of stability found recently for vacuum-phase advances well above 90°͓R. Pakter and F. B. Rizzato, Phys. Rev. Lett. 87, 044801 ͑2001͔͒. In particular, a solenoidal focusing field profile that goes from a smooth sinusoidal-like function to a sharp-edged step-funcion as a continuous parameter is varied is considered. It is shown that the new regions are always present, but may be very sensitive to changes in the focusing field profile. Specifically, as the focusing field becomes more localized, the new regions become narrower, occur at higher vacuum phase advances, and present a larger number of nonlinear resonances and chaos in the beam envelope phase space. Although in all the cases analyzed here it was found that there is a relatively thick layer of regular trajectories isolating the matched solution from the chaotic region, self-consistent simulations show that envelope phase-space chaos may affect beam dynamics, leading to some small emittance growth.

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“…Similarly, the fhst order moments of eq (6) yield the following & = XL &: = -k;,,z:, t k& < zm > ~ < 9 > k;Yc= c d _" &y: = -k&y,-< e > (8) Note that if h,, = 0, eq (7) forms a closed sets of 8 equations, and eq (8) forms two sets of two closed equations If h,, # 0, eqs (7) and (8 of an infinite hierarchy of moment equations ) form the beginning For the case of alternating gradient focusing, and when the bends occupy only a fraction of the lattice, the focusmg constants J&, kj&, and the bend radius of curvature pO are dependent on s This s-dependence of the external forces implies that there will not be a constant energy-like quantity However, as in ref [l], if lipO~,~pOy, and p. are constants representing average quantities, we may define a transverse energy H:…”

Section: Modelmentioning

confidence: 99%

“…The concept of transverse energy conservation xas used in ref [l] to study emrttance growth m bends This built upon earher studies which have calculated changes in emittance also using a transverse energy constraint For example, ennttance growth associated with non-uniform spacecharge distributions was examined in refs [8]- [lo] Emittance growth due to mitial beam displacements and mismatches with and without space-charge and momentum spread has been studied in, refs [ll-13,171, and references therein…”

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Emittance growth in heavy ion rings due to the effects of space charge and dispersion

Barnard¹,

Craig²,

Friedman³

et al. 1998

AIP Conference Proceedings

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We review the derivation of moment equations which include the effects of space charge and dispersion in bends first presented in ref [l] These equations generahze the famihar envelope equations to mclude the dispersive effects of bends TTe review the application of these equations to the calculation of the change m emrttance resulting from a sharp transition from a straight section to a bend section, usmg an energy conservation constramtComparisons of detailed 2D and 3D snnulatrons of intense beams m rmgs using the WARP code (refs [2;3]) are made with results obtamed from the moment equationsWe also compare the analysis carried out in ref [I], to more recent analyses, refs [4,5] We further exammr self-consistent distributions of beams m bends and discuss the relevance of these distributions to the moment equation formulation

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Possible Emittance Increase through Filamentation Due to Space Charge in Continuous Beams

Cited by 198 publications

References 0 publications

Space charge modeling of dense electron beams with large energy spreads

Space charge modeling of dense electron beams with large energy spreads

The role of the focusing field profile on the stability of periodically focused particle beams

Emittance growth in heavy ion rings due to the effects of space charge and dispersion

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