Analysis of Alpha Particle Behavior in EBT Reactors

A formalism has been developed in terms of a drift kinetic equation with a Fokker-Planck collision operator to calculate alpha-particle loss and energy-deposition-rate coefficients for one position in space and for steady-state operating conditions in an ELMO Bumpy Torus (EBT) reactor. Pitch-angle and energy-scattering terms were retained in the collision term so that the analysis provides information on alpha-particle behavior due to pitch-angle scattering into loss regions in velocity space and information on alpha energy deposition during slowing down in the device. A square-well magnetic-field shape is assumed and the resulting particle loss rates and energy-deposition rates are calculated. For typical EBT reactor parameters, results show that while 80 to 90% of the alpha particles are scattered into a pitch-angle loss region and lost from the device, more than 70% of the alpha-particle energy is deposited in the core plasma and about 1 to 2% goes to alphas retained in the plasma as ash. Parametric studies are performed, and the sensitivity to plasma potential, the pitch angle, the width of loss regions, and computational procedures are analyzed.