Deep Dielectric Charging Effect Measurement Using DDCE Monitor

The deep dielectric charging effects monitor (DDCEM) that measures the surface leakage currents and the internal charging potentials of the dielectric is equipped on a Chinese medium Earth orbit (MEO) navigation satellite to monitor deep dielectric charging risk in real time and research deep dielectric charging effects onboard. In this article, we focus on the largest observed charging event and take it as an example to discuss the possible applications of the DDCEM data. As expected, the location of the peak currents and potential values are between 4.4 and 7.7 L-shells. Smaller L-shells mean larger currents and potential variations. Some lag effect (~minutes) is observed due to the dielectric charging time constant. Further analysis shows that DDCEM can be used as an onboard conductivity measuring apparatus or an onboard charging electric field monitor. The calculated flame retardant 4 (FR4) dielectric top surface’s conductivity
$\sigma _{\mathrm {top}}$
(
$9.1\times 10^{-14} - 1.5\times 10^{-13}$
S/m) and the bottom surface’s conductivity
$\sigma _{\mathrm {bottom}}$
(
$1.1\times 10^{-14} - 3.4\times 10^{-14}$
S/m) are much larger than the conductivity (
$ < 2.5\times 10^{-15}$
S/m) in National Aeronautics and Space Administration (NASA)-HDBK-4002A. The calculated peak charging electric field near the FR4 dielectric top surface (
$2.6\times 10^{3} - 1.2\times 10^{4}$
V/m) and bottom surface (
$5.5\times 10^{3} - 3.1\times 10^{4}$
V/m) is much less than the risk value 106 V/m, which is from the European Space Agency (ESA) final report, meaning that there was no charging risk during the period of this study.