Cyclotron thermonuclear instability in the reactor-tokamak

The paper analyses the stabilty of a Tokamak reactor plasma containing a group of fast α-particles formed in thermonuclear reactions. The perturbations of such a plasma at frequencies close to the harmonics of the α-particle cyclotron frequency are considered. The corrugation of the Tokamak magnetic field and the longitudinal inhomogeneity of the α-particle cyclotron frequency associated with it are taken into account. It is shown that, in Tokamak reactor conditions, development of the cyclotron thermonuclear instability with a growth rate proportional to the square root of the α-particle density - predicted by the theory of homogeneous plasma oscillations - is impossible. In a Tokamak this instability is suppressed by the corrugation of the magnetic field. Cyclotron interaction with fast magnetoacoustic waves from trapped α-particles is analysed and is shown to result in growth of these waves with an increment which is linear with respect to the α-particle density. (author)