8.2.4                 Plasmasphere

a.              The plasma parameters representing the terrestrial plasmasphere shall be taken from the Global Core Plasma Model (GCPM) [RN.8].

NOTE 1      Profiles of typical plasmasphere densities versus altitude are given in Annex H.3.3.

NOTE 2      Outputs are densities of electrons, protons, helium ions and oxygen ions. Input parameters are: time, geocentric radial distance, solar magnetic local time, solar magnetic latitude and Kp index.

b.              For spacecraft charging assessments, Kp=9 shall be used in the GCPM model to represent a worst case situation.

NOTE              This is because the plasmasphere is a moderating influence on spacecraft charging, and so the worst case is considered to be when the plasmasphere is small which occurs when geomagnetic activity is high.