6.2.2                 Maximum resistivity

a.              In order to limit differential voltage, a maximum current density of J = 10 nA/cm2 through the dielectric shall be used to calculate the maximum resistivity of dielectric materials.

NOTE              This current is a recommended upper bound of the current through dielectric material to other parts on Earth orbiting spacecraft. It is not the electron irradiation current used for testing.. For example, a small sunlit area of aluminium coupled to a larger area of material in eclipse can lead to a current flow through a dielectric beneath the aluminium as large as the photocurrents (~ 4nA/cm2 for aluminium) plus any difference in secondary emission current.

b.              The method used for resistivity measurement shall be justified.

NOTE              Some methods are described in Annex D.3.