A scaling law for high density tokamaks and its application to J.I.P.P. T-II device

A scaling law for high density and high current tokamaks is presented on the basis of the non-local theory of drift instability of current-carrying plasma with the assumption of quasi-linear saturation level. It is shown that the energy confinement time scales as tau sub(E) proportional to nq/√T (n and T are the averaged density and temperature) due to the pure current-driven mode in the relatively lower density region and tau sub(E) proportional to B/√n (B is the toroidal magnetic field) due to the usual collisional drift instability in the higher density region. The effects of the trapped particles are assumed to be negligible. A text-experiment of the scaling law on the J.I.P.P. T-II device where both the tokamak operation and the operation with the superposition of helical fields are possible, is proposed. (auth.)