CHARACTERISTIC PEAKED PROFILES OF ION TEMPERATURE AND TOROIDAL ROTATION VELOCITY IN JT-60 HOT ION MODES

In JT-60, hot ion modes (T(i)(0) = 9-13 keV, H-0 beam into H+ plasma) exhibiting peaked profiles of the ion temperature, T(i)(r), and the toroidal rotation velocity, V(t)(r) have been obtained with an effective safety factor q(eff) approximately 10. Experiments have been performed to study the characteristics of these peaked profiles in which q(eff) was scanned over the range 4.5 < q(eff) < 15. Peaking of the profiles of T(i)(r) and V(t)(r) occurs within a limited region. Moreover, the boundary of the region of improved performance is well characterized by the q = 1, 2 and 3 surfaces. The improvement in global confinement in JT-60 hot ion modes is attributed to the substantial increase in the volume of the enhanced confinement region within the q = 3 surface, in which region the peaked T(i) profile is generated.