Angular scattering in charge‐exchanging beams: Implications for neutral beam formation via negative ions

Abstract

Coupled Boltzmann equations for particles with two charge states have been solved to describe the angular evolution of a beam which is charge exchanging through collisions with a background vapor. The solutions are applied to the processes D⁰+Cs→D⁻+Cs⁺ and D⁻+Cs→D⁰+Cs + e using measured differential cross sections where available. By accelerating and stripping a D⁻ beam, an intense high‐energy beam can be formed for thermonuclear fusion experiments and reactors. It is concluded that angular scattering does not place a significant limit on the beam quality, although the cesium line density must be the minimum to reach a charge‐state equilibrium in the beam.