Investigation of the shear layer versus the last closed flux surface on TEXT-upgrade

The Texas Experimental Tokamak Upgrade (TEXT-Upgrade) has a set of 41 magnetic sensor coils that are used to determine the magnetic flux surface configuration of plasma discharges. These reconstructions include the x-points and the separatrix. These magnetic flux surface reconstructions and simultaneous data from several Langmuir probes are used to determine the locations of features in the shear layer, specifically the flux surface where Er=0, and of the last closed flux surface (LCFS). This is done for several different magnetic configurations. These results are then compared to results obtained from other tokamaks.