Achievement of Quasi-steady Reversed Shear Mode
JT-60U has pursued the sustainment of reversed shear mode since its mode has achieved equivalent break even conditions. Recently, with feedback control of neutron emission rate, enhanced confinement (H factor of 1.7) in the reversed shear configuration has been sustained for 4.3 seconds (by 18 times of energy confinement time) in JT-60U.
Fig. Typical discharge waveforms
| Beta limit was improved by combining an H mode (edge transport barrier) with an internal transport barrier under increasing the triangularity up to 0.3. The feedback-control has been conducted within this limitation, so that a high plasma perfo-rmance with 3.5 MJ at 1.5 MA is sustained as shown in the above figure. Higher perfor-mance with increasing the current will be aimed at in JT-60U. |  Fig. profiles |