Non-zero net current collected by floating dielectrics


I am running simulations using the latest SPIS-6.1.0 version. When I apply dielectric material to a spacecraft and allow it to reach its floating potential, I find that the net current from ions and electrons does not trend to zero. Instead it reaches equilibrium at some slightly positive net current.

However, this does not make physical sense as this implies the spacecraft hasn’t reached its floating potential and should still be charging more negatively.

I also notice that in the output data, there are two separate potential outputs for the surface nodes and electrostatic nodes. But the user manual does not further explain the difference here, or why for dielectrics the net current is non-zero at equilibrium. Is there an internal current for dielectric materials which is not being plotted or output by the solver? How might I be able to add this to the outputs so that the net current is accurately tracked? Any help is much appreciated, thank you!