Physics Mechanisms of Toroidal Rotation Profile and Properties of Momentum Transport in JT-60U

抄録

The roles of momentum transport on the toroidal rotation velocity (V_t) 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_φ) and the convection velocity (V_conv), and to calculate V_t profiles driven by external torque input by neutral beams (NBs). The measured V_t profiles with and without the external torque input are almost reproduced by χ_φ and V_conv in low-β (β_N < 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_φ increases with increasing heating power, and decreases with increasing plasma current (I_p). In H-mode plasmas, χ_φ is smaller than that in L-mode plasmas under similar experimental conditions. It is found that χ_φ, which is separated from the non-diffusive term increases with increasing heat diffusivity (χ_i), χ_φ/χ_i ∼ 1-3, and -V_conv increases with increasing χ_φ, V_conv/χ_φ ∼ -2.5 to -0.7 m^-1 , in H-mode plasmas.