Multiple electron stripping of heavy ion beams

Abstract

One approach being explored as a route to practical fusion energy uses heavy ion beams focused on an indirect drive target. Such beams will lose electrons while passing through background gas in the target chamber, and therefore it is necessary to assess the rate at which the charge state of the incident beam evolves on the way to the target. Accelerators designed primarily for nuclear physics or high energy physics experiments utilize ion sources that generate highly stripped ions in order to achieve high energies economically. As a result, accelerators capable of producing heavy ion beams of 10 to 40 MeV/amu with charge state 1 currently do not exist. Hence, the stripping cross sections used to model the performance of heavy ion fusion driver beams have, up to now, been based on theoretical calculations. We have investigated experimentally the stripping of 3.4 MeV/amu Kr⁺⁷ and Xe⁺¹¹ in N₂; 10.2 MeV/amu Ar⁺⁶ in He, N₂, Ar, and Xe; 19 MeV/amu Ar⁺⁸ in He, N₂, Ar, and Xe; 30 MeV He⁺¹ in He, N₂, Ar, and Xe; and 38 MeV/amu N⁺⁶ in He, N₂, Ar, and Xe. The results of these measurements are compared with the theoretical calculations to assess their applicability over a wide range of parameters.