Abstract

Although there have been a few proposals for fusion reactors employing plasmas far out of thermodynamic equilibrium (such as migma and inertial-electrostatic confinement), there has never been a broad, systematic study of the entire possible range of such devices. This research fills that gap by deriving fundamental power limitations which apply to virtually any possible type of fusion reactor that uses a grossly nonequilibrium plasma. Two main categories of nonequilibrium plasmas are considered: (1) systems in which the electrons and/or fuel ions possess a significantly non-Maxwellian velocity distribution, and (2) systems in which at least two particle species, such as electrons and ions or two different species of fuel ions, are at radically different mean energies. These types of plasmas would be of particular interest for overcoming bremsstrahlung radiation losses from advanced aneutronic fuels (e.g. ^3He-^3He, p-^{11}B, and p- ^6Li) or for reducing the number of D-D side reactions in D-^3He plasmas. Analytical Fokker-Planck calculations are used to determine accurately the minimum recirculating power that must be extracted from undesirable regions of the plasma's phase space and reinjected into the proper regions of the phase space in order to counteract the effects of collisional scattering events and keep the plasma out of equilibrium. In virtually all cases, this minimum recirculating power is substantially larger than the fusion power, so barring the discovery of methods for recirculating the power at exceedingly high efficiencies, reactors employing plasmas not in thermodynamic equilibrium will not be able to produce net power. Consequently, the advanced aneutronic fuels cannot generate net power in any foreseeable reactor operating either in or out of equilibrium. Moreover, D-^3He can only produce net power when burned in thermodynamic equilibrium, which means that in any possible D-^3He reactor, the neutrons and tritium produced by D-D side reactions cannot be reduced below a certain level, which is calculated. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).