Effect of Current Density Profile on q(a) Limit in Non-Circular Tokamak TNT-A

抄録

The effect of the current density profile on the limit of the safety factor q(a) in the non-circular tokamak TNT-A is described in this paper. The safety factor q(a) is measured by magnetic probes and one-turn loops. The current density profile is estimated from the shape of the plasma boundary with an equilibrium code. A gas puffing system and pulse forming network (PFN) circuit for the Joule current are used to control the profile. The limit of q(a) increases from 2.6 to 4.0 as the current density profile becomes flatter and the current density profile parameter enters the unstable region for the m=3 and 4 external kink modes. This limit of q(a) determines one of the boundary of the operational stable region in TNT-A.