The Surface Charge Density node adds an additional surface charge density ρs, which satisfies the boundary condition:

where ndown is the outward normal vector from the downside domain. This feature is available when the Material model of its parent feature (Gas, Liquid, Solid) is Insulator or Charge transport with the checkbox Enable custom space charge density in addition to the predefined values selected. Note that for the Charge transport model, the surface charge at the dielectric interfaces has already been taken into account through the Dielectric Interface, Surface Transport feature.

Enter a value or expression for the Space charge density ρs (SI unit: C/m2). The default is 0 C/m2.