Current diffusion, heat transport modelling, and linear gyrokinetic stability
analysis have been carried out on a set of seven hybrid discharges from AUG,
DIII-D, JET and JT-60U, in order to gain better understanding of the physics
underlying this promising candidate scenario for ITER.Within this dataset, the
GLF23 model has a higher accuracy than the Weiland model in predicting the
temperature profiles in the region 0.3 < ρ < 0.8. The core heat transport
appears to be similar between hybrid discharges and standard H-modes, and
also among hybrid discharges with very different H factors. Projections to
ITER show that Q = 10 can be obtained with the hybrid scenario using an
alternative scaling without β degradation. However, additional off-axis current
drive and current profile control might be needed for the ITER hybrid scenario,
in order to achieve its full potential for high βN on extended duration. |