December 1998, January 1999
Previous theme groups which had conducted JT-60U experiments for the past two years were reorganized. Two theme groups, CORE PLASMA and DIVERTOR/SOL PLASMA, will lead JT-60U experiments in the coming years. Research subjects treated by the theme groups are as follows.


H-modes, Internal transport barrier, Core transport analysis, Confinement scaling laws, Fast particles, etc.

Sustainment of high performance, Improvement of steady-state performance, High confinement plus current drive, Current drive by NBI, LH and ECCD, High confinement with high bootstrap fraction, MHD, disruption, etc.


Effects of W-shaped divertor, impurity generation mechanism and transport, Tritium retention, He exhaust, etc.

The primary target for 1999 is to improve plasma confinement in high ne regime. For the purpose, the both theme groups will collaborate to understand a reason for a confinement degradation at high densities which is commonly observed in tokamak experiments, and to find out a countermeasure. High-triangularity(δ) H-modes with N-NBI, reversed shear modes or RI-modes are possible operational scenarios to access to the goal. Long sustainment of high QDTeq (~0.5 for 1 s) will be attempted by optimizing reversed shear discharges. To ensure the concept of SSTR with high beta, high confinement and full current drive (CD), JT-60U will challenge to produce high performance full-CD plasma with N-NBI at Ip ~ 2 MA and QDTeq ~ 0.3. Experiments on divertor/SOL plasma are expected to enhance pumping performance of W-shaped divertor in high ne and high-δ regime with divertor pumping at inside and outside channels. In addition, steady sustainment of radiative divertor by means of sophisticated feedback control of divertor radiation will be one of the targets for 1999. Physics experiments on ITB, heat and particle transport, MHD, disruption, energetic particles, MARFE, and SOL flow are also foreseen.