|Budget Amount *help
¥2,400,000 (Direct Cost : ¥2,400,000)
Fiscal Year 1997 : ¥1,300,000 (Direct Cost : ¥1,300,000)
Fiscal Year 1996 : ¥1,100,000 (Direct Cost : ¥1,100,000)
As a model for turbulent transport in inhomogeneous plasmas the interchange turbulence was studied. This instability is universal for magnetically confined plasma, and has similarity to Rayleigh-Taylor instability and Benard convection. It is possible to refer knowledge obtained for these instabilities within the fluid dynamics. The magnetohydrodynamic model for describing the interchange turbulence includes two non-dimensional characteristic numbers, Rayleigh number, Ra, and Prandtl number, Pr. These non-dimensional numbers are also used for classifying the Benard convection. For evaluating The transport due to the interchange turbulence, the non-dimensional number, Nusselt number, Nu, was employed. In this study the Prandtl number is usually assumed Pr=1. The obtained results are summarized in the following.
1.For Ra <greater than or similar> 10^4, the saturation level of interchange turbulence becomes non-stationary and show a sawtooth-like oscillation. 2.For Ra <greater than or similar> 10^5, the shear flow componet exceeds the vortex componet driven by the interchange mode with the enhancement of the sawtooth-like oscillation of total fluctuation energy. 3.For Ra <greater than or similar> 10^5, the Nusselt number corresponding to the turbulent transport increases intermittently. With the increase of Ra, Nu at the burst becomes large and the period of burst becomes long. However, the time average of Nu does not depend on Ra. 4.The behavior of the nonlinear interchange mode seems consistent with the ELMs (Edge Localized Modes) observed in the H-mode of tokamak or ste