The Mechanism Of Transport Under ES Perturbation And New Approach To Numerical Solving ES Field

In this thesis, the particle transport in tokamak devices due to wave-particle resonance induced diffusion is studied. The diffusion coefficient for thermal circulating particles is derived both an-alytically using quasilinear theory, and numerically using a test particle code, and the obtained diffusion coefficient agrees with each other in its validity regime. Dependence of the diffusion coefficient on turbulence intensity, turbulence radial mode structures and particle energy is inves-tigated. It is found that the diffusion coefficient is proportional to the turbulence intensity, and the diffusion is maximized for Et≈Ti, and kr△0≈1. Here, Et is the test particle energy, Ti is the thermal ion temperature, △0 is the distance between neighboring mode rational surfaces, and 1/kr is the half width of the fine radial mode structure on each rational surface. For energetic circulating particles, the diffusion coefficient is derived in another way. It is proportional to Et-3/2, which is observed in previous simulations. For deeply trapped particles, the diffusion coefficient is scanned under various parameters. It is found some strange phenomena which can not be explained by this model.An alternative approach for numerically solving the Poisson equation by using physical model is introduced, which is a way to solve partial differential equation without finite difference method. For 1D systems, it become a integration with arbitrary boundary conditions. For 2D and 3D sys-tems, by using the cutoff method according to the charge, the computational complexity is of the lowest order(0(n)). By comparing the result computed from cutoff method with the exactly solu-tion, the error is negligible small. This approach is especially suitable for parallel computing. This method can also be applied to numerically solving other partial equations whose Green functions exist in analytic expression.