Initial Results of Producing Tokamak in RELAX

Abstract

The safety factor and magnetic shear profiles play an important role in plasma confinement, particularly in cases of nearly zero or reversed magnetic shear. This may be closely related to the formation of internal transport barriers. We have upgraded the low-aspect ratio reversed field pinch (RFP) machine RELAX to produce tokamak plasmas, which will be used to investigate the physics of magnetic shear within a single machine. The preliminary measurements of the radial profile of the magnetic field have been conducted under different conditions in two separate experiments. The initial results indicate that standard tokamak and RFP plasmas are produced within a single machine due to an upgraded power supply that increased the toroidal field. This unique feature enables systematic studies of the physics of magnetic shear across the negative-to-positive region.