Development and Application of NUMIT for Realistic Modeling of Deep-Dielectric Spacecraft Charging in the Space Environment

• Main Author: Beecken, Brian P
• Format: Report
• Language: English
• Subjects: Astronautics; CHARGE TRANSFER; CHARGE TRANSPORT ALGORITHM; Computer Programming and Software; COMPUTERIZED SIMULATION; CRRES(COMBINED RELEASE AND RADIATION EFFECTS SATELLITE); DEEP-DIELECTRIC CHARGING; DIELECTRICS; ELECTRIC FIELDS; ELECTRICAL CONDUCTIVITY; Electricity and Magnetism; ELECTRON FLUX; FIELD INTENSITY; ISOTROPISM; MATHEMATICAL MODELS; MODELING CHARGING; MONTE CARLO METHOD; NUMIT(NUMERICAL ITERATIONS); PE63401F; POLYMERIZATION; SOFTWARE TOOLS; SPACE ENVIRONMENTS; SPACE TECHNOLOGY; SPACECRAFT CHARGING; SPECTRA; SYNCHRONOUS SATELLITES; Unmanned Spacecraft; WUAFRLEF004167

NUMIT has been refined, developed, and greatly enhanced so that it can be used to model and predict the deep charging of dielectrics on spacecraft. The new tool, called AF-NUMIT2, can now model isotropically incident electron fluxes from realistic energy spectra that change with time. The model has been extended to incident electron fluxes an order of magnitude lower than before (less than = 10 keV), and aspects of the model have been checked against Monte Carlo simulations. Electron energy flux spectra, as measured by CRRES, have been used in dozens of simulations of Kapton charging over multiple days. Kapton has been modeled with both dark conductivities and radiation induced conductivities extending over two orders-of-magnitude. The result is a surprisingly consistent relationship between maximum internal electric field strengths and conductivity, regardless of the particular incident electron spectra. The original document contains color images.