Reactor aspects of counterstreaming-ion tokamak plasmas

The paper examines those properties of a beam-driven counterstreaming-ion tokamak plasma that are most relevant for application to DT fusion reactor design. A toroidal plasma is considered, in which the D and T ions are grouped in two distinct, quasi-thermal velocity distributions, oppositely displaced in velocity along the magnetic axis. Such velocity distributions are set up by introducing all ions by means of neutral beams injected parallel and anti-parallel to the toroidal magnetic field. By postulating that in steady-state there exists an equipartition of energy between the directed ion motion and the total plasma thermal motion, ion velocity distributions and plasma properties are derived that are in good agreement with previous Fokker-Planck results. Fusion reactivity, power gain Q, and power density Pf are calculated over wide ranges of injection energy and electron temperature, and the results demonstrate a trade-off between Q and Pf.