Ion Thermal-Diffusion In The Texas Experimental Tokamak

Profiles of the ion thermal diffusion coefficient chi-i have been determined experimentally for several TEXT plasma discharges. In the confinement region, the inferred values of chi-i are larger than the values predicted by neoclassical theory by a factor of two to six. No evidence of a reduction of thermal losses through the ion channel is found after injection of hydrogen pellets. The inferred electron thermal conductivities are larger than the ion thermal conductivities by an average factor of three. The anomaly in chi-i is compared with transport coefficients predicted by different models that describe the eta-i instability.