Core Vf and Ti Profiles and Transport in TFTR DD and DT Plasmas with Lithium Conditioning
Authors: C. E. Bush, R. E. Bell, and B. LeBlanc
High performance DT plasmas have been obtained using neutral beam heating with lithium (Li) conditioned graphite walls in TFTR. Values of tE > 300 ms have been obtained with neutron source rates of > 1018 n/s and ntT » 1021. Also, ion temperature (Ti) > 40 keV and toroidal velocity (Vf) > 800 km/s have been obtained. The Ti(R,t) and Vf(R,t) profiles show strong gradients near the plasma core with ÑVf > 3.5 ´ 106/s and E´B shearing rate > 2´105/s realized. This strong E´B flow shear is consistent with formation of a "transport barrier" in the plasma core. Measured Vf , Ti, and carbon density, nc, profiles from charge-exchange recombination spectroscopy (CHERS) and neoclassical calculations of poloidal velocity, Vq, are used to assess the roles of the pressure and velocity contributions to Er (or E´B) with varying Li conditioning. The profiles and gradients and resulting confinement and transport are found to vary with the amount of Li applied and the Li deposition technique. Correlations between the Vf and Ti profiles and recycling and impurity behavior as implied from edge carbon and Da light and Li deposition are also observed.