Theoretical Studies of Collective Ion Acceleration in a Linear Beam-Evacuated Drift Tube System

This paper deals with recent theoretical studies and ideas on Collective Ion Acceleration (CIA) in systems in which a linear intense electron beam is injected into an evacuated drift tube. The source of ions in these systems is the result of electrical breakdown of a dielectric insert in the anode or ionization of a localized gas cloud near the beam entrance. A phenomena basic to these CIA experiments is the virtual cathode formation process. We present numerical studies of this process using a new particle simulation code that features a non-uniform mesh. Also, we present a model of the entire CIA process, delineating the role of the virtual cathode.