December 1996


After the divertor modification, plasma operation condition in JT-60U is to be re-optimized. A detailed study has been started on the discharge sequence and plasma configuration for high confinement modes suitable for the new divertor. It has been started to produce the new database of plasma shape and position required for the real time feedback control of JT-60U discharges with the new divertor.

Systematic study have progressed on transport barriers of high confinement modes such as H-mode, high-beta-p mode and reversed shear mode. Concerning the edge transport barrier in H-mode, width of the edge pedestal is proportional to the poloidal gyro radius of thermal ion in the ELM-free phase. Whereas, in the ELMy phase, the width is much wider than that in the ELM-free phase and is affected by ELM activity.


Operation schedule for three weeks in January and February was discussed and determined. Improvement of the current drive performance with the negative-ion-based neutral beam (N-NB) is the highest priority in physics issues. Parametric dependence of current drive performance with the N-NB was investigated with the ACCOME code for next run scheduled in February '97. The N-NB power over 3 MW with the energy of 350-400 keV will be expected in the run after the aging operation in January '97.


For the divertor modification, technical review committee meetings were held to supervise the new divertor diagnostics such as the reciprocating probe, the divertor interferometer etc. "Radiative divertor in the reversed shear plasmas in JT-60U" and "Impurity modeling in JT-60U" were presented from JT-60U in the meeting on "Interaction between gas and plasma" at Nagoya, 5-6 December.