The Theory of Plasma Confinement in a Tokamak at High Temperatures

The dynamics of the plasma in a Tokamak are examined in cases where the path lengths are so long that the particles can justifiably be divided into ''blocked'' and ''in-transit'' categories. The paper consists of two parts, in the first of which the kinetic equilibrium of the plasma in a Tokamak is considered. In the determination of the equilibrium configuration of the magnetic field account is taken of the ''banana'' currents of blocked and in-transit particles, which are similar to the Larmor current in a homogeneous magnetic field. Expressions are derived for the values of the diamagnetic signal and the displacement of the column measured during Tokamak experiments. The dynamics of the plasma column are calculated on the basis of equations for the heat balance and particles with neo-classical transfer coefficients. A value is found for the limiting pressure of the plasma in a Tokamak β < (a/R)3/2 q-2 (β = 8πp/B20, where p is the plasma pressure, B0 is the toroidal magnetic field and q the factor of assurance calculated at the boundary of the plasma column). The limiting pressure is determined from the Kruskal-Shafranov condition for the supplementary current occurring during entrainment of in-transit particles by blocked particles drifting through them. The second part of the paper analyses the remaining difference between the neoclassical and experimental values of the transfer coefficients in dilute plasma. Models are discussed of the anomalous transfer due to low-frequency turbulence of the in-transit and blocked particles. (author)