Scattering of Electromagnetic Waves by Drift Vortex in Plasma

<正> In a quasi-two-dimensional model,the scattering of incident ordinary electromag-netic waves by a dipole-electrostatic drift vortex is studied with first-order Born approximation.The distribution of the scattering cross-section and total cross-section are evaluated analyticallyin different approximate conditions,and the physical interpretations are discussed.When thewavelength of incident wave is much longer than the vortex radius （kia<<1）,it is found that theangle at which the scattering cross-section reaches its maxim depends significantly on the approxi-mation of the parameters of the vortex used.It is also found that the total scattering cross-sectionhas an affinitive relation with the parameters of the plasma,while it is irrelevant to the frequencyof the incident wave in a wide range of parameters of the vortex.In a totally different range ofparameters when incident wave is in the radar-frequency range （then kia<<1,the wavelengthof incident wave is much shorter than the vortex radius）,the numerical procedure is conductedwith computer in order to obtain the distribution and the total expression of the scattering cross-section.Then it is found that the total scattering cross-section in the low frequency range is muchlarger than that in high frequency range,so the scattering is more effective in the low frequencyrange than in high frequency range.