The oscillating solutions of the magnetic fields may arise on an axisymmetric model by using first order finite elements.In addtion,they may also occur for nonuniform grids.The paper analyses the cause of forming oscillating solutions and the behaviour of oscillating solutions.The methods of cancelling the oscillation are suggested.

The quasilinear differential equations are solved by finite difference method with non-equidistant scheme. The evolution of the runaway electron distribution function and wave energy density are obtained in interval of electron parallel velocity. These solutions are shown to be more complete than that given in [1] and [2] for both the stationary case and the evolution of functions in one-dimension. The results are useful for further study of runaways.

The nonlinear complex parabolic partial differential equation is solived by the predictor-correction scheme. The numerical solutions are attained for the nonlinear propagration of ALFVEN wave-packet in collisional plasmas. The results show the effect of collision damping can not be neglected, whereas the nonlinear Landau damping is a weak effect compared with the collision one.

The stress distribution of toroidal field D-shaped coils for the TOKMAK fusion reactor is solved by the finite element method. It has been shown that the results of mechanical stress are in agreement with that of the JET toroidal field coils, the shearing stress is small along conductor, approximate to pure tension coil.