Analysis of particle species evolution in neutral-beam injection lines

Abstract

Analytic solutions to the rate equations describing the species evolution of a multispecies positive ion beam of hydrogen due to charge exchange and molecular dissociation are derived as a function of the background gas (H₂) line density in the neutralizing gas cell and in the drift tube. Using the solutions, calculations are presented for the relative abundance of each species as a function of the gas‐cell thickness, the reionization loss in the drift tube, and the neutral‐beam power as a function of the beam energy and the species composition of the original ion beam.