Core and edge toroidal rotation study in JT-60U

The relation between toroidal rotation velocities (V-t) in the core and edge regions is investigated in H-mode plasmas with a small external torque input from the viewpoint of momentum transport. The toroidal rotation velocity in the core region (core-V-t) gradually varies on a timescale of similar to 20 ms after a rapid change in the toroidal rotation velocity in the edge region (edge-V-t) at the L-H transition. This timescale of similar to 20 ms is consistent with a transport timescale using the momentum diffusivity (chi(phi)) and convection velocity (V-conv). In steady state, a linear correlation between the core-and edge-V-t is observed in H-mode plasmas when the ion pressure gradient (del P-i) is small. This relation between core-and edge-V-t is also explained by momentum transport. The V-t profiles with a large del P-i are reproduced in the core region of r/a similar to 0.2-0.7 by adopting a residual stress term 'Pi(res) = alpha(k)chi(phi)del P-i' proposed in this paper. Here r/a is the normalized plasma radius and alpha(k1) is a radial constant. Using this formula, V-t profiles are reproduced over a wide range of plasma conditions. Parameter dependences of the edge-V-t are investigated at a constant ripple loss power, ripple amplitude and plasma current. A reduction in the CTR-rotation is observed with decreasing ion temperature gradient (del T-i). Here CTR refers to the counter-I-P direction.