A computational investigation of divertor plasma scaling laws

Usually, tokamak core scaling laws are written in terms of dimensionless geometrical quantities and parameters corresponding to Coulomb collisionality, gyro-motion, and plasma beta. However, Lackner [K. Lackner, Comments Plasma Phys. Controlled Fusion 15, 359 (1994)] observed that the temperature profiles also must be the same to obtain the same atomic physics in the divertor region of similar discharges. He obtained a scaling indicating that none of the present tokamaks could be made similar to the International Thermonuclear Experimental Reactor (ITER) [G. Janeschitz et al., J. Nucl. Mater. 220–222, 73 (1995)], but implicitly retained only two body interactions. Subsequent work [P. J. Catto et al., Phys. Plasmas 3, 3191 (1996)] demonstrated that non-two-body effects (multistep radiation, excitation, and ionization processes as well as three body recombination) cannot be ignored for plasma densities above 1019 m−3; the regime in which the ITER divertor must operate. In this reactor relevant regime, scali...