(EX/P3-22) Driving Mechanism of Toroidal Rotation and Momentum Transport in JT-60U

Abstract.  It is widely recognized that plasma rotation profiles play one of the most critical roles for plasma transport and MHD stability. In JT-60U, the toroidal rotation in the direction antiparallel to the plasma current, i.e. counter (CTR) direction has been observed with no or small momentum input from near-perpendicular neutral beam injection (PERP-NBI). An inward electric field induced by a ripple loss of fast ions was considered as a candidate for the CTR rotation in the peripheral region [Koide Y., et al., Plasma Phys. Control. Nucl. Fusion Research 1, 777 (1992)]. In the core region, momentum diffusivity and inward convective velocity were separately estimated from the transient momentum transport analysis [Nagashima K., et al., Nucl. Fusion 34, 449 (1994)]. In this paper, the driving mechanism and momentum transport were systematically investigated both in the peripheral and core regions by using the various combinations of NBIs (CO, CTR, and PERP) and wide dynamic range of toroidal field ripple with and without ferritic steel tile (FST) in JT-60U. Main results are as follows: (i) fast ion losses due to the toroidal field ripple induce CTR rotation in the peripheral region, (ii) the magnitude of CTR rotation increases with increasing the ripple loss power in the peripheral region. (iii) We have also found that toroidal rotation velocity profiles in the core region can be almost explained by momentum transport considering diffusivity and convective velocity estimated from transient momentum transport analysis.

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