Dependence of energy confinement time on toroidal magnetic field in the TUMAN-3M tokamak

Abstract

The influence of toroidal magnetic field on the energy confinement time τE in the ohmic H-mode has been studied in the TUMAN-3M tokamak with low magnetic field. The experiments were performed at a toroidal magnetic field of BT = 0.68−1.0 T, which is about twice as large as that (0.25–0.5 T) studied in analogous experiments on the NSTX and MAST spherical tokamaks. The results are indicative of a strong dependence of the energy confinement time on toroidal magnetic field: τE ∝ BT0.75–0.8. This scaling is much stronger than that projected for the ITER (τE_IPB98 ∝ BT0.15), while being somewhat weaker than the scalings observed on the NSTX and MAST devices. The stronger (as compared to the ITER scaling) dependence of τE on BT observed in these experiments should be taken into account in designing thermonuclear facilities with small aspect ratios and toroidal magnetic fields—in particular, fusion neutron sources.