STUDIES ON AN IMPORTANT NEW WAVE MODE OF EQUATORIAL SPERAD F
WU YING(Physics Department, Huazhong University of Science and Technology, Wuhan 430074)WANG JING-FANG(Department of Space Physics, Wuhan University, Wuhan 430072)
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.