| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2002: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2001: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2000: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
In torus plasmas such as tokamaks and stellarators, investigation of the relation between MHD properties of the plasma and high energy particles like alpha particles is inevitable and important to realize a thermo-nuclear fusion reactor. In this study, following theoretical and numerical analyses are performed concerning the correlation between three-dimensional MHD equilibrium/stability and high energy particles in non-axisymmetric torus plasmas;
1) Discrete eigenmodes existing in the spectral gap of Alfvan continuum are studied by using a global MHD stability code based on the stellarator approximation. It is found that the mode structure and frequency of the TAE modes are changed by the change of the rotational transform profile due to the finite plasma beta. The kinetic effect of high energy particles on the TAE mode is being studied perturbatively now.
2) Both the local analysis based on the WKB approximation and the global analysis by using a three-dimensional ideal MHD stability c
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ode CAS3D are performed for the ballooning mode specific to the helical system. From the detailed comparison between the local and global analysis, the availability of the local analysis, in which the validity of the approximation is pointed out to be questionable, is verified. In order to estimate how the kinetic effect can change the ideal ballooning mode, local analyses solving the kinetic ballooning mode equations are done. We found that the finite Larmor radius (FLR) effect stabilizes short wave length modes and the compressibility is effective to stabilize long wave length modes.
3) Development of a Monte-Carlo code has been started to estimate kinetic effects from the view point of particles as a final goal. At the first step, the neoclassical transport is being investigated for a plasma in a helical system. Heliotron J. Though it is difficult to argue the results quantitatively, suppression of the neoclassical transport due to the bumpy field component and the radial electric field, which is demonstrated in the previous studies, is verified qualitatively.
4) In the analysis of a rippled tokamak, free-boundary MHD equilibria are obtained by considering discreteness of toroidal coils using a Biot-Savart code KMAG and a three-dimensional MHD equilibrium code VMEC. Finite beta dependence of the toroidal field ripple and its effect on the ripple loss of high energy particles are clarified. Less
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