Multimode Analysis of the Hollow Plasma Channel Wakefield Accelerator

Abstract

The hollow plasma channel is analyzed as an accelerating structure. The excitation of the channel by an ultrarelativistic beam is analyzed. Coupling to the fundamental and all higher-order azimuthal modes of the excited electromagnetic fields is derived. Implications of this work for plasma-based accelerators, including beam loading and beam breakup, are discussed. Small initial transverse displacements of the beam are shown to couple to deflecting modes in the channel. The asymptotic growth rate of the resultant beam breakup instability is analyzed and a method for reducing the growth is proposed.