Numerical Research Of Electron Temperature Gradient Driven Modes In Shaped Plasmas

Microinstabilities driven by temperature gradient are proposed as the possible candidate to explain the anomalous transport phenomenon in magnetically confined plasmas. Study of plasma shaping effects on temperature gradient modes in highβplasmas is one of advanced theoretical topics at present. In the thesis, a gyrokinetic model with integral eigenmode equation is developed by employing the local equilibrium model of shaped tokamak plasmas. The code is updated accordingly. The magnetic curvature and gradient drift effect, the transit effect, the finite Larmor radius effect and the electromagnetic effect related to finiteβare all retained. However, the trapped particle effect is neglected.In the thesis, we investigate the effect of elongationκ, aspect ratio A , Shafranov shift gradient (?)R₀/(?)r and triangularityδon the electron temperature gradient (ETG) driven mode. Dependence of critical threshold of electron temperature gradient on these shape parameters is presented. Moreover, effects ofβ_e and plasma shape parameters on the electromagnetic ETG driven mode are studied preliminarily. It is found that increase ofβ_e has a stabilizing effect on the ETG mode, while effects of the shape parameters on the ETG mode are almost similar to the results in the electrostatic limit. Numerical results are shown in the thesis. It is found that increasing elongation has a stabilizing effect on the ETG mode but depends on the wavelength, while decreasing aspect ratio has a beneficial effect on the stability of ETG mode. The effect of Shafranov shift gradient is comparatively weak and is also relative with wavelength. Increasing triangularity has a weak stabilizing effect on the ETG mode in the long wavelength, but has an unstable effect on the ETG mode in the short wavelength. In most cases, the increase of critical electron temperature gradient threshold accompanies the decreasing growth rate in longer wavelength regimes.