Validation of Internal Charging Tools With Experiments in REEF

The objective of the European Space Agency validation of internal charging tools using the realistic electron environmental facility (REEF) project is to assess the performance of internal charging tools against experimental measurements made at the REEF facility at the University of Surrey. REEF uses an intense strontium-90 beta-emitting radioactive source to simulate the space environment. This project is complemented by parallel experiments to derive material parameters, conducted by ONERA. We report results from REEF with four different types of dielectric material and compare these results to predictions from the DICTAT, MCICT, and NUMIT internal charging simulation tools. The materials under investigation are Cirlex, PEEK, FR4, and Neoflon (FEP). We find that in many cases, the computer codes struggle to recreate REEF results, which raises significant questions over the validity of internal charging mitigation analyses. We show the advantages and disadvantages of each model and suggest what features could be added in order to improve the fidelity of their predictions.