Measurements of the current density profile with tangential Thomson scattering in RTP

The electron drift velocity (v(d,e)) profile is measured with tangential Thomson scattering (TTS). From this, the current density (j) profile is determined, extending over 60% of the plasma diameter (2a) with a spatial resolution of 12% of a. The statistical error of similar to 10% is in agreement with the expected accuracy based on simulation studies. Two analysis methods are compared and found to agree. Results of TTS in electron cyclotron heated discharges with peaked and hollow j profiles are in good agreement with neo-classical resistivity.