On going and planned D-T experiments on TFTR

Summary form only given. In the first phase of deuterium-tritium (D-T) experiments on TFTR, routine D-T operation was established to permit quantitative evaluation of the characteristics of D-T plasmas relative to those of comparable D-D plasmas. It was immediately observed that the isotope effect gave a significant increase in the overall energy confinement in D-T plasma relative to that of the D-D plasma. This isotope effect coupled with extensive lithium pellet limiter conditioning resulted in a record central fusion-triple product of n/sub Hyd/ /spl tau//sub E/*T/sub i/=8.3/spl times/10/sup 20/ m/sup -3//spl middot/5/spl middot/keV. Energy confinement has been increased to over 0.3 sec in the supershot (peaked density, hot-ion mode) regime in TFTR with aggressive lithium conditioning. As a result, the fusion performance is no longer limited by confinement but is now limited by instability driven by high central pressure (/spl beta/) and by high pressure gradients. A series of experiments have been undertaken in the reverse shear (RS) and high internal inductance (high l/sub i/) regimes to enhance core stability. The reverse shear regime sustains larger pressure gradients as predicted and exhibits transitions to an enhanced core particle and energy confinement regime within the region of reversed shear. Enhanced performance characteristics include n/sub e/(0)-1.2/spl times/10/sup 20/ m/sup -3/, T/sub i/(0)/spl sim/24 keV, T/sub e/(0)-8 keV, and pressure peaking factor of -7. The l/sub i/ regime also permits higher core /spl beta/ to be obtained and hence higher Q to be sustained. On-going experiments are directed toward further enhancing the performance in the reverse shear regime at higher plasma current and toroidal magnetic field in order to enhance fusion performance and especially alpha particle density to support alpha particle physics studies.