PIC simulations of spacecraft charging and the neutralization process by plasma emission Original Research Article

We examined the spacecraft charging and its neutralization using dense plasma emission by performing Particle-In-Cell (PIC) simulations. In a two-dimensional simulation space, a conducting body representing a spacecraft is immersed in a magnetized plasma. In the ionospheric plasma, the body becomes negatively charged with respect to the space potential due to large thermal velocity of electrons. In order to neutralize the negative charging of the body, we continuously emit dense plasma from the body. We particularly examined the electron/ion flux to the charged body and the corresponding potential variation. It is shown that the negatively charged body is neutralized mainly by the enhancement of ion flux of the emitted plasma. As the potential approaches to the space potential, the ion current to the body decreases and the net current to the body becomes zero. In the transient process of the charge neutralization, we could see very turbulent current variation at the emitted plasma cloud region, which may cause electromagnetic perturbation in the vicinity of the body.