Alpha Particle Dynamics in Muon-Boosted Fusion Propulsion System

Abstract

In a previous paper, we demonstrated that negative muons resulting from antiproton annihilation in a relatively cold deuterium-tritium (DT) plasma confined in a gasdynamic mirror (GDM) can result in catalyzing on average over 100 fusion reactions. The alpha particles produced by these reactions could contribute significantly to heating the background plasma toward ignition. In fact, it was pointed out that on the basis of energetics only, muon-catalyzed fusion would reduce the amount of antiprotons required to achieve thermonuclear burn by about 60%. This scenario, however, does not address the issue of alpha particle confinement in the GDM, and thereby leaves open the question of their true effectiveness in providing the heating noted above. In this paper, we address this problem by noting that, as they slow down, these alpha particles can escape from the system. We deduce explicit expressions for alpha particle density as a function of energy, and calculate the mean energy of these particles allowing simultaneously for slowing down and escape as reflected by the confinement time. Assuming that the alpha particles slow down primarily on the electrons, as is the case in relatively cold plasmas, we find that muon catalyzed fusion is indeed effective in heating the plasma in a GDM device.