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

Abstract

The roles of momentum transport on the toroidal rotation velocity (Vt) profile and the properties of transport coefficients are found by transient momentum transport analysis. The perturbation technique enables us to evaluate the momentum diffusivity (χφ) and the convection velocity (Vconv), and to calculate Vt profiles driven by external torque input by neutral beams (NBs). The measured Vt profiles with and without the external torque input are almost reproduced by χφ and Vconv in low-β (βN < 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, χφ increases with increasing heating power, and decreases with increasing plasma current (Ip). In H-mode plasmas, χφ is smaller than that in L-mode plasmas under similar experimental conditions. It is found that χφ, which is separated from the non-diffusive term increases with increasing heat diffusivity (χi), χφ/χi ∼ 1-3, and -Vconv increases with increasing χφ, Vconv/χφ ∼ -2.5 to -0.7 m-1 , in H-mode plasmas.