Strategy of intense ion beam accumulation by use of charge exchange injection

Abstract

Accumulation of ions in a storage ring using charge exchange injection gives the possibility of storing the ion beam with parameters applicable to plasma experiments. Beam quality on the target can be defined by the factor of beam quality K b=1.5 Pa, where P is specific power, and a is beam radius. A simple formula, which allows one to estimate the value of K b for arbitrary accelerator parameters, is derived. This formula shows that in the absence of an electron cooling system (ECS) the main limitations appear due to intra beam scattering, increasing momentum spread of the stored beam. A more accurate analysis for ITEP-TWAC project is made by use of Monte-Carlo code. Four different storage scenarios are considered: fast scenarios with high intensity of injected beam and comparatively short accumulation time (10–20 injection cycles); slow scenarios with long accumulation time (100–200 injected cycles) (for both cases options with and without ECS have been considered). For all options, central injection scheme is used, where charge exchange target coincides with the center of the coasting beam. By optimization of the factor K b the optimal parameters (number of injections, intensity, emittance, momentum spread) have been calculated for each scenario.