Destruction of magnetic surfaces by high-n ballooning mode

Effects of high-n ballooning modes on plasma confinement are examined. Kinetic effects or finite-resistivity should cause reconnection of the field lines and magnetic surfaces of the tokamak are destroyed by the ballooning instabilities. Tearing parity modes are important for the magnetic surface destruction. The diffusion coefficient of the field line is linearity proportional to the amplitude of the perturbed field. Beta limitation of tokamak systems by the ballooning mode is discussed. (author)