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

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