Evaluation of plasma current profile on a low-aspect-ratio tokamak reactor

Sengoku, Seio

To evaluate a bootstrap-current-profile quickly, a simple method has been developed with a novel approximation. This results in that all of the neoclassical diffusion coefficients for the gradient become the polynominals only in variables of inverse aspect-ratio, , effective charge, Z and collisionality, , in the whole range of variables. The resultant current profile is well reproduced from ITER benchmark with transport code including the case with internal-transport-barrier. This method is applied to a commercial reactor, VECTOR, low-aspect-ratio tokamak reactor. The fraction of bootstrap-current, I/I, are evaluated as: 55%, 60% and 100% for the normal-shear, weakly-reversed-shear and strongly-reversed-shear (with current-hole) plasmas, respectively.