Abstract
Internal charging caused by energetic electrons is a recognized threat to critical space infrastructure such as navigation and communication satellites. In this paper the electric field developed inside selected on-board dielectrics over a 10-year period in a GPS-like orbit is modelled using actual charging currents measured directly in orbit. The charging currents provide both charge deposition and dose rate inputs to the model, the latter allowing the introduction of radiation induced conductivity (RIC) to improve realism. As expected we find that RIC is a mitigating factor for the electric fields but they can still become very large e.g. a 1.0 mm thickness of PEEK under 0.5mm of Al shielding would be at risk of breakdown almost throughout the mission. We also find that RIC tends to reduce sensitivity to space weather perturbations of the environment such as the April 2010 storm event. This seems physically reasonable but we also know that some satellite anomalies do correlate quite well with space weather and short term (daily) electron fluence increases. We recommend that correlation of anomaly data sets with electric field models of this type is undertaken in future: this will require accurate materials parameters and also needs to take account of sudden depletion of the electric field due to discharges. In addition more charging current sensors with greater shielding levels (>2mm Al equivalent) should be flown to allow modeling of a wider range of realistic cases, including inside well-shielded electronic boxes.