ESF中一种重要新波模的探讨

本文从计入离子-中性粒子碰撞频率Vin效应的等离子体二流体方程组出发,导出统一描述ESF小尺度和中小尺度区域现象的二维静电模型.对模型方程进行了详细的线性波理论分析.结果表明,晚间赤道F层可存在正能波和负能波;Vin效应的影响是否重要依赖于波数和离子梯度漂移速度u_d乘积的大小.在小尺度区域,Vin影响较小,本文模型将变成我们已提出的小尺度无碰撞模型;而在中小尺度区域,Vin效应很重要,本文模型将得到著名的Rayleigh-Taylor不稳定性结果,Vin项对波的影响可以是致稳作用也可能是失稳作用,RT不稳定性波模对应于负能波分支.

STUDIES ON AN IMPORTANT NEW WAVE MODE OF EQUATORIAL SPERAD F

A two-dimensional electrostatic model describing unitedly the phenomena of the transitlo-nal and intermediate regions in ESF is derived from the plasma two-fluid equations taking the ion-neutral collisional effect into account. Linear analyses of the model show that there can exist the positive and negative energy waves in the equatorial F layer at night and whether the ion-neutral collisional effect is important or not depends upon the product of the wavenum-ber and the ion diamagnetic drift. The ion-neutral collision has stable effect on positive energy wavt and unstable effect on negative one. It is showed that the well known Rayleigh-Tay-lor instability in the intermediate region can be obtained from our model and what is more, the Rayleigh-Taylor instability corresponds to that of negative energy wave.