Session KP01 - Poster Session III.
POSTER session, Tuesday afternoon, March 23
Exhibit Hall, GWCC
The stability beta limit for low aspect ratio tokamak plasmas can be of the order of 50 % or higher. Equilibrium pressure in such plasmas is likely to be anisotropic, i.e., P_\parallel\ne P_\perp, due to strong auxiliary heating power, such as RF or neutral beam heating. Here P_\parallel is the parallel ( to magnetic field \mathbfB) plasma pressure and P_\perp is the perpendicular plasma pressure. A solution for the perturbed particle distribution of the linearized drift kinetic equation in the extremely low aspect ratio limit ( i.e. aspect ratio A \rightarrow 1 ) is obtained. It is found that bootstrap current <\tau J_bB > depends on parallel pressure gradient \partial P_\parallel/\partial\psi and magnetic field gradient \partial B/\partial\psi, where angular brackets denote flux surface average, \tau = 1 - ( 4\pi / B^2 ) ( P_\parallel - P_\perp), J_b is the bootstrap current, B =|\mathbfB| and \psi is the poloidal flux function. The Pfirsch-Schluter current is also calculated from the fluid momentum equation. Parallel plasma current in such plasmas is therefore completely determined.