A Scaling Law for High Density Tokamaks and Its Application to J.I.P.P. T–II Device

Abstract

A scaling law for high density and high current tokamaks is presented on the basis of the nonlocal theory of electrostatic current-driven drift instability in both collisionless and collisional regimes with the assumption of quasilinear saturation level. It is shown that the energy confinement time scales as τ_E∝nq(a)⁄\sqrtT_e (n, T_e and q(a) are the averaged density, electron temperature and the safety factor at the plasma edge.) in relatively lower density region and τ_E∝B⁄\sqrtn (B is the toroidal magnetic field) in higher density region where a combined effect of the electron collisions and of a plasma current works. Trapped particle effects are assumed to be negligible and no magnetic fluctuation is considered. A test experiment of the scaling law on the J.I.I.P.T–II device where both tokamak operation and the operation with superposition of helical fields are possible is proposed.