Three-dimensional fluid simulations of the Cs plasma release in the ionosphere

Releasing plasma cloud is an efficient way to manage ionosphere properties. In this paper, we establish a three-dimensional fluid model to simulate the spatiotemporal evolution of released Cs plasma. Four types of particles are taken into account: released neutral Cs, ambient O, Cs+ and electron, among which the Cs+ and electron move according to the classical ambipolar diffusion. Meanwhile, photoionization induced by solar radiation and recombination of Cs+/electron are included in model as two chemical reactions. Based on this model, we investigate the influence of three factors: initial velocity of neutral Cs cloud, photoionization rate and altitude. The initial velocity can change the whole distribution of plasma cloud. When there is no velocity or velocity along the background magnetic field, the plasma cloud shows an ellipsoid shape and moves with neutral cloud. If the velocity is perpendicular to the magnetic field line, the cloud will be stretched in the same direction and does not move. We investigate the influence of photoionization rate under different initial velocities, and find that with the photoionization rate increasing, more and more particles remain in the initial release position. Moreover, the altitude affects the density of ambient O and temperature result in the diffusion coefficient and drifting velocity reducing and then the size of bulk plasma inclines to be reduced at lower altitude.