Derivation and Testing of Computer Algorithms for Automatic Real-Time Determination of Space Vehicle Potentials in Various Plasma Environments

摘要

A new algorithm for spacecraft charge detection based on a drop in electrostatic analyzer ion count spectra at energy levels higher than the level of vehicle potential has been derived. This so-called Count Drop algorithm was found to be effective in cases where, owing either to rapidly fluctuating potentials or significant secondary ion production, there were substantial ion counts in channels below the level of peak charging. In such cases, the Count Ratio (renamed Count Rise) and Distribution Function algorithms, both based on a sharp increase in counts at the level of charging, were able to detect maximum vehicle potential. A corresponding algorithm based on a sharp decrease in ion distribution function, called the Distribution-function Drop Algorithm has also been tested using SCATHA data. The ion count spectra associated with 11 instances of low earth orbit spacecraft charging in polar latitudes have been examined. Keywords: Statistical data. (KR)