Physics Mechanisms of Toroidal Rotation Profile and Properties of Momentum Transport in JT-60U
The roles of momentum transport on the toroidal rotation velocity (V<sub>t</sub>) profile and the properties of transport coefficients are found by transient momentum transport analysis. The perturbation technique enables us to evaluate the momentum diffusivity (χ<sub>φ</sub>) and the convection velocity (V<sub>conv</sub>), and to calculate V<sub>t</sub> profiles driven by external torque input by neutral beams (NBs). The measured V<sub>t</sub> profiles with and without the external torque input are almost reproduced by χ<sub>φ</sub> and V<sub>conv</sub> in low-β (β<sub>N</sub> < 0.4) plasmas. At higher β, the local pressure gradient plays a role in determining the local value of intrinsic rotation velocity. Concerning the momentum transport, χ<sub>φ</sub> increases with increasing heating power, and decreases with increasing plasma current (I<sub>p</sub>). In H-mode plasmas, χ<sub>φ</sub> is smaller than that in L-mode plasmas under similar experimental conditions. It is found that χ<sub>φ</sub>, which is separated from the non-diffusive term increases with increasing heat diffusivity (χ<sub>i</sub>), χ<sub>φ</sub>/χ<sub>i</sub> ∼ 1-3, and -V<sub>conv</sub> increases with increasing χ<sub>φ</sub>, V<sub>conv</sub>/χ<sub>φ</sub> ∼ -2.5 to -0.7 m<sup>-1</sup> , in H-mode plasmas.
- Plasma and Fusion Research
Plasma and Fusion Research (3), S1007-S1007, 2008