Numerical Study of Plasma Depletion Region in a Satellite Wake

We demonstrated the existence of a distorted plasma depletion region in a satellite wake through 3-D electrostatic particle-in-cell (PIC) plasma simulations. It is commonly known that a wake is formed in the downstream region of a satellite in a magnetized plasma flow. Our simulation shows that the plasma depletion region in the wake is distorted in the plane perpendicular to the static magnetic field. This distortion is asymmetric with respect to the plasma flow direction in the satellite rest frame of reference. We found that the asymmetric structure of the plasma depletion region is caused by nonuniform local drift motion of electrons around the depletion region. By test particle simulations in which electron trajectories are traced in fixed fields obtained in the PIC simulation, we confirmed that cold electrons that have a Larmor radius less than the size of the satellite can cause the asymmetric structure of the plasma depletion in the wake.