Spacecraft charging thresholds in single and double Maxwellian space environments

With the single Maxwellian electron distribution model of space environment, the results suggest that the ambient electron temperature is the only decisive parameter controlling the onset of spacecraft charging. The value of the critical temperature is a property of the surface material. The ambient electron density has no influence on the onset at all. With the double Maxwellian electron and ion model of space environment, the results suggest that positive charging, negative charging, triple-root charging, and of course, no charging are all possible behaviors. A domain diagram for various behaviors is presented as an example. In the triple-root situation, the middle root is unstable. The spacecraft potential may require either of the static roots; which root is acquired depends on the initial condition and the way the environment changes in time. Hysteresis of spacecraft potential may occur. The critical or threshold temperature derived in the single Maxwellian model plays an important role in the triple-root condition of the double Maxwellian model