| Research Abstract |
To understand the mechanisms of H-mode and the transports revealed in tokamak plasmas, we proposed a new model theory. The aim of this project research is to develop the model and to make a consistent theory including the transports. Our original model of the L/H transition is based on the bifircation of radial electric field, which is caused by the (intrinsic) bipolar diffusion near the plasma edge. In this research, we refined the model equations and analyses. The following effects are covered ; 1. the radial derivative of electric field on the transition condition, 2. neutral particles which extract the momentum from host ions, 3. the boundary condition of the core plasma which is determined by the transport balance between the scrape-off-layer (SoL) plasma, 4. the inter-relation between the transition condition and the boundary condition, 5. the transport scaling in SoL and divertor plasmas, 6. the sheared rotations due to the radial electric filed. Above studies were published in journals listed in references. Some new researches were reported in the proceedings of international conferences of IAEA, EPS and in the domestic conferences.
The theory has been extended to one dimensional model, which can tell the effect on the radial structure of the plasma profile. To obtain the plasma profile including the edge, the effects of radial electric field on fluctuations is needed. This structure is found to be effective to the anomalous diffusion. Further analysis is necessary to examine the transport matrix due to the anomalous processes. A part of this research was done for the improved confinement modes (including H-mode), and a new model theory of the peaked profile mode has been published. We found that the sheared rotation plays an important role to determine the profile. We plan to extend this research of H-mode to various improved modes in future.
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