Studies On Resistive Wall Instability Driven By Plasma Flow In A Slab Model

The efficiency of Tokamak is confined by the beta limit in magnetic confinement of toroidal plasma, and the concept of Advanced Tokamak proposed can improve the plasma pressure through a thin perfect conducting wall around the plasma. And it can lead to the increase of the Tokamak efficiency. However, there is no perfect conductor, and then a new instability mode will be excited by the finite resistivity of conductor. This conductor which has finite resistivity is called resistive wall, and this mode is called resistive wall mode. Resistive wall mode can be stabilized by wall rotation, at the same time a new instability can be inspired by this rotation, which is named as resistive wall instability driven by flow. This large scale instability is critical to magnetic confinement of toroidal plasmas, especially to ITER.In this thesis, we study on the characters of resistive wall instability driven by plasma flow in slab model for ideal plasma and nonideal plasma which has viscosity respectively. We obtain eigenmode equations by normal mode method, and study on the effect of parameters of wall and viscosity on resistive wall instability driven by plasma flow.In Chapterâ… , reviews on background, MHD instability modes and methods for studying them are briefly discussed, including the research situation and necessity of resistive wall instability driven by plasma flow.In Chapterâ…¡, we adopt ideal MHD equations to study resistive wall instability driven by plasma flow, give the eigenmode equation by normal mode method, and then obtain all solutions of this eigenmode equation through numerical method directly. Among all isolines, there are only two of which the growth rates are zero. One of them is stability boundary of system, and the other stands for the locality of instability window. The growth rate in window is higher than other regions in unstable area.In Chapterâ…¢, the effect of parameters of wall on resistive wall instability driven by plasma flow is investigated. The locality of resistive wall doesn't effect on the stability boundary of system but the value of growth rate in unstable region. The larger the plasma flow equilibrium velocity is, the more unstable the system is. But the plasma flow equilibrium velocity can be slowed by changing locality of resistive wall. Resistive wall is used to stabilize perturbative for large wavelength, so that those perturbative for short wavelength are easy to grow up. The resistivity of wall has no effect on stability boundary, but ability in magnetic diffusion is stronger while resistivity is larger, and then system is more unstable.In Chapterâ…£, the effect of the viscosity on resistive wall instability driven by plasma flow is studied. The viscosity doesn't effect on stability boundary, but can decrease the value of growth rate in unstable region. There is the second stable region for nonideal plasma which has viscosity. Because of the viscosity, the perturbative frequency effects on the stability of the system, so that the frequency can't be esteemed to zero.Finally, a brief summary and future works end the thesis.