The Modeling Of Flow Fields And Numerical Analyses Of The Helical Instabilities Of Arc Plasma

The plasma of arc discharge has many characteristics such as higher temperature, focusof power and controllable reaction, etc. It has been applied widely in industries and other newtechnology domain. It is needed to design the arc plasma generator which can produce largeareas and uniform plasma arc with higher current and many atmospheric pressures. Butbecause of the experiment and technology limited, it is still in the half experiment state.Therefore, research on the equilibrium and helical magnetic instabilities of are plasma is avery important subject. Also previous studies are mostly needed some assumptions and getsome approximate results. Hence it is required to there are some numerical studies on theevolution of are plasma. The research results on the heat transfer and fluid flow in the DC arcplasma generator and the plasma reactor can give the information in designing big current arcplasma generator, and they also can be compared with the experiment. This thesis researchesthrough the helical instability of arc plasmas and the characteristics of heat transfer and fluidflow of arc plasma. The helical arc is described by the electromagnetic equations in anelectrostatic approximate on and the equations are solved by linear perturbation theory. Andthe growth rate of the helical instability can be evaluated; Also the evolution of the heattransfer and fluid flow is computed. The contents are:Firstly, basic concept and characteristic of arc plasma, significance of research anddevelopment actuality are introduced.Secondly, the analytical method and linear perturbation theory are adopted to solve theelectromagnetic equations. Especially the radiation models are presented and the explicitanalytic expressions are derived in the presence of the radiate on transfer energy, from whichthe helical instabilities of arcs can be given. It is found that, in comparison with the resultswithout radiation, the arc stable area is reduced.Thirdly, the effects of the external axial magnetic field on are numerically studied. Themagnetohydrodynamic equations in an electrostatic approximation serve as the starting pointof the theory and the marginal Maecker's number and the growth rate of the helical instabilityare determined. Numerical results show that the short wavelength perturbation can bestabilized by positive direction magnetic field, whereas the long wavelength perturbation canbe stabilized by reverse magnetic field. The current profile, arc current, and are column radiuson the helical instabilities of arc have also discussed.Fourthly, a numerical method is developed for the two-dimensional axis-symmetricmodel of evolution of arc plasma based on a reasonable physical model. The distributions andevolutions of the current density, temperature, velocity field, etc. of the arc plasma are computed. Especially the influence of the different radiation forms, the different cathodeconfiguration and the current density distribution of the cathode are analyzed.Fifthly, a numerical simulation is presented to describe the heat flow, fluid flowevolution phenomena in a plasma reactor with lateral gas injection which can simulate theeffect of interaction of space aircraft and the atmosphere plasma in laboratory. The effect ofthe cold flow is researched and the results show that the pressure and injection angle of coldflow is significant of the temperature and velocity distributions in the fluid flow field.Finally, conclusions and the future work are given in the thesis.