Confinement studies of neutral beam heated discharges in TFTR

The TFTR tokamak has reached its original machine design specifications (Isub(p)=2.5 MA and Bsub(T)=5.2T). Recently, the D0 neutral beam heating power has been increased to 6.3 MW. By operating at low plasma current (Isub(p) approx. 0.8 MA) and low density (n-barsub(e) approx. 1 x 1019m-3), high ion temperatures (9 +- 2 keV) and rotation speeds (7 x 105 m/s) have been achieved during injection. At the opposite extreme, pellet injection into high current plasmas has been used to increase the line-average density to 8 x 1019 m-3 and the central density to 1.6 x 1020 m-3. This wide range of operating conditions has made possible scaling studies of the global energy confinement time in both ohmically and beam heated discharges as well as more detailed transport studies of the profile dependence. (author)