Space-charge-induced emittance growth in an elliptical charged particle beam with a parabolic density distribution

Abstract

where L is the length of the drift space. The impulse can also be expressed as a change in the divergence angle, given nonrelativistically in the paraxial approximation by We present a simple analytical model of emittance growth caused by nonlinear space-charge forces using a qExL mv2 'laminar, parabolic-density beam. The model allows us to explain a surprising and important result that space-chargeinduced emittance growth is larger in the plane with the larger semi-axis.where m is the mass of the beam particles.

Beam dynamics studies and parametric characterization of a standing wave electron linac

“…Therefore the initial bunch charge should be small enough to ensure no loss of beam through the aperture. As linear space charge effects strongly influence bunch behaviour [9][10][11][12] it is important to understand how bunch characteristics change with total charge per bunch. Table 1 shows the values of several bunch attributes at the end of the linac as a function of the total charge per bunch.…”

Emittance concept and growth mechanisms

“…The most serious case is known as the envelope resonance or envelope instability, which leads to growth of the transverse emittances and beam envelopes. m e envelope instability be avoided by limiting the zero- In this model [20] we consider a continuous, beam With a parabolic charge density, an elliptical transverse cross section, and zero initial emittance. We will suppose that as the beam travels over a short distance z, the space-charge impulse changes the transverse momentum of the particles, but the particle positions do not change appreciably: we assume that the parabolic density profile is constant.…”

Longitudinal space-charge geometric factor for an elliptical beam

“…The fields in the case m = 1 have previously been given by Lapostolle [8,9] et al Similar problems but with a confocal elliptic conducting boundary are much more difficult and have to be treated by solving the Poisson equation.…”