Artificially Structured Boundary for a high purity ion trap or ion source

A plasma enclosed by an Artificially Structured Boundary (ASB) is proposed here as an alternative to existing ion source assemblies. In accelerator applications, many ion sources can have a limited lifetime or frequent service intervals due to sputtering and eventual degradation of the ion source assembly. Ions are accelerated towards the exit canal of positive ion sources, whereas, due to the biasing scheme, electrons or negative ions are accelerated towards the back of the ion source assembly. This can either adversely affect the experiment in progress due to sputtered contamination or compromise the integrity of the ion source assembly. Charged particle trajectories in the proximity of an ASB experience electromagnetic fields that are designed to hinder ion-surface interactions. Away from the ASB there is an essentially field free region. The field produced by an ASB is considered to consist of a periodic sequence of electrostatically plugged magnetic field cusps. A classical trajectory Monte Carlo simulation is extended to include electrostatic plugging of magnetic field cusps. The conditions necessary for charged particles to be reflected by the ASB are presented and quantified in terms of normalized parameters.