The neoclassical transport theory is developed for an axisymmetric toroidal plasma containing highly energetic α-particles as produced by fusion events. It is shown that the α-particle fluxes in this case have a weaker dependence on the aspect ratio than at lower energies since the prevailing collisional effect is a drag. The bootstrap current results to be reduced by the presence of fusion α-particles.
The transport properties of an axisymmetric toroidal plasma containing an arbitrary number of impurity species are considered for the case that all species are in the collision-dominated regime. Energy transfer between the different species, and in particular between electrons and ions, is taken into account. This yields expressions for the particle and heat fluxes applicable to a wide range of parameters.
The diochotron instability of a thin, tenuous, cylindrical layer of charged particles, whose gyro-radius is of the order of the mean radius of the cylindrical layer, is investigated using the Vlasov equation. Two distribution functions are considered which give practically the same density in the physical space, but are quite different in the velocity space: in the first the velocity spread is practically zero; in the second the particles oscillate around the mean radius of the cylindrical layer. It is shown that the first distribution exhibits the usual diochotron instability, while the second one does not. It is also shown that, however small the velocity spread, the thickness of the cylindrical layer cannot go to zero. Its minimum value is roughly determined by equating the plasma frequency to the cyclotron frequency.
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