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Parametric Studies of Image-Charge Effects in Small Aperture Alternating-Gradient Focusing Systems

Image charges have important effects on an intense charged-particle beam propagating through an alternating-gradient (AG) focusing channel with a small circular aperture. This is especially true with regard to chaotic particle motion, halo formation, and beam loss. In this paper, we examine the dependence of these effects on system parameters such as the filling factor of the AG focusing field, the vacuum phase advance, the beam perveance, and the ratio of the beam size to the aperture. We calculate the percentage of beam loss to the conductor wall as a function of propagating distance and aperture, and compare theoretical results with simulation results from the particle-in-cell (PIC) code PFB2D.