We investigate the mechanism of space potential formation due to a diverging magnetic field on a rarefied weakly ionized plasma flowing supersonically by performing a hybrid simulation. Ions and neutrals are treated by the particle-based direct simulation Monte Carlo method, while electrons are treated as a fluid to save time and memory. We apply an electron continuity equation in order to treat the electron velocity independently of the ion velocity. We find the number density of ions (and electrons) distributed along the magnetic field. We also find electron rotation along the flowing direction. Since we remove the current-free condition assumed in our previous study, we find that the longitudinal variation in the space potential agrees reasonably well with our previous experimental results.