[en] This report describes the work done by Science Applications International Corporation to study the effects of energetic particles on the microstability of a high temperature tokamak. The effects of an energetic population on ballooning modes in a large aspect ratio, shifted circular flux surface tokamak equilibrium are investigated with the newly developed gryokinetic numerical technique. The gryokinetic equations for the background ion and electron, as well as that of the energetic population are solved directly as an initial problem. The energetic particles are modeled with a slow-down distribution in energy. It is found that the ballooning mode stability of the plasma with an energetic species of increasing concentration does not differ much from an increase in the background plasma beta, except for possible energetic particle drift resonances. This result is encouraging to the idea that energetic particles such as alphas may be used to stabilize the ballooning modes in a fusion reactor

[en] The free energy associated with the anisotropy in the velocity space of a microwave heated hot electron distribution can drive the mirror mode unstable. The real frequency of this instability is of the same order as the diamagnetic drift of the hot electron

[en] The effect of impurities on low frequency drift modes of a toroidally-confined plasma is investigated by the gyro-kinetic equation. It is assumed that electrons are in the banana regime and ions in the plateau regime. Impurity collision damping is found to be significant in the usual trapped electron mode. A new instability due to the impurities can occur for normal profiles and impurities peaked at the center. Quasi-linear considerations show that impurities will be driven outward if such an instability occurs

[en] A ballooning mode equation that includes full finite Larmor radius effects has been derived from the Vlasov equation for a circular tokamak equilibrium. Numerical solution of this equation shows that finite Larmor radius effects are stabilizing

[en] Neoclassical transport for an elliptic tokamak in all collisional regimes is investigated by the technique of partitioning the velocity space. It is found that in a tokamak of moderate elongation, particle and ion heat confinement times are increased by a factor of sigma², where sigma is the ratio of vertical minor radius to horizontal minor radius. Ripple diffusion in an elliptic tokamak is also studied. Ion heat conductivity due to ripples is reduced by a factor of approximately sigma²

[en] The drift motions of trapped particles in a tokamak field with ripples lead to a new transport process in large tokamaks in addition to the diffusion process due to particles trapped in the ripples. We study this problem by solving the bounce averaged drift kinetic equation with a model collision operator. It is shown that the ''banana drift diffusion'' is proportional to the collision frequency when the poloidal banana drift frequency is smaller than the effective collision frequency. This result is contrary to earlier predictions. In a reactor regime, this loss mechanism is shown to be unimportant

[en] The ion distribution function in a thermal barrier is modeled by counter streaming Maxwellian distribution. Its stability with respect to parallel propagating electrostatic and electromagnetic modes is investigated both analytically and numerically. It is found that the electrostatic mode is stable if T/sub e//T/sub i/ greater than or equal to 3.5 and the electromagnetic mode is stable if the streaming velocity is less than the Alfven speed. The latter condition implies the barrier potential must be less than the average magnetic energy per particle

[en] An expression was calculated for parallel ion flow in general nonaxisymmetric geometry, both in fluid and banana regime. Ambipolar conditions in these regimes are obtained from the ion flux. A relaxation which is quite different from the classical viscosity effect is thus derived. This relaxation however resembles the coupling between the radial temperature gradient and the relaxation of parallel ion flow obtained by Rosenbluth et al., in banana regime of an axisymmetric system. When the nonaxisymmetry becomes smaller and smaller, the relaxation of parallel ion velocity then comes from the quasi-neutrality requirement on the higher order fluxes. The nonaxisymmetric effect is mixed with the axisymmetric effect. As a basis of the calculation, the axisymmetric calculation of Rosenbluth et al., for banana regime is extended to intermediate and fluid regime. A small perturbation to this axisymmetric result is obtained by including a higher order non-ambipolar flux in the calculation. Final result shows that an exponential type relaxation term should be added to the axisymmetric equation if there are small ripples on the tokamak field. This term may be significant for a large machine such as PLT

[en] It is shown that in general the stability of a hot electron symmetric tandem mirror is the same as the stability of its barrier-plug cell alone, plus an additional limitation on the center cell length such that the center cell Alfven frequency is higher than the average barrier-plug E x B drift and the hot electron precession frequency. Stability of the hot electron barrier-plug cell is studied extensively

[en] The electron-cyclotron maser and whistler instabilities are investigated in a unified treatment. The dispersion relation is solved numerically and extensive parametric studies are performed. We find that growth rates for both instabilities increase with perpendicular hot-electron temperature and the size of the loss cone