Unifying Role of Radial Electric Field Shear in the Confinement Trends of TFTR Supershot Plasmas

Abstract
A model is presented to explain the favorable ion thermal confinement trends of supershot plasmas in the Tokamak Fusion Test Reactor (TFTR). Turbulence suppression by radial electric field shear is important to reproduce the measured temperatures. Supershot confinement scalings are reproduced in more than sixty discharges, including favorable core power scaling and variation with isotopic mass, density peakedness, edge recycling, and toroidal rotation. The results connect the transitionless supershot regime with improved confinement regimes which are attained through sharp confinement transitions in the core or edge.