Large-scale Plasma Vortex in the Magnetotail of Venus

Using the observations by the Analyzer of Space Plasmas and Energetic Atoms on Venus (ASPERA-4) onboard Venus Express, Previous studies found a large-scale plasma vortice of solar wind hydrogen ions ($H^{+}$) and Venus ionospheric oxygen ions ($O^{+}$) in the magnetotail of Venus. The vortex is counterclockwise when viewed from the tail towards the planet. We conducted a statistical analysis of the ASPERA-4 moment data calibrated by Fedorov to investigate the plasma characteristics in Venusian magnetotail. The statistical results showed that there are large-scale vortices of the solar wind $H^{+}$ and Venus ionospheric $O^{+}$ in both the Venus-Solar-Orbital (VSO) and Venus-Solar-Electrical (VSE) coordinate systems, but they are clockwise. Considering that neither counterclockwise nor clockwise plasma vortices can generate a magnetic field consistent with the observed magnetic structure in the Venusian magnetotail, and no complete plasma vortex is observed in the Mars magnetotail with a magnetic structure similar to that of Venusian magnetotail, concluded that there may not be large-scale plasma vortices in the Venusian magnetotail, and that more satellite observations are needed in the future to investigate the plasma characteristics on Venus.