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[1] The extensive database of plasma measurements from Los Alamos geosynchronous satellites is used to derive a statistical characterization of the geosynchronous fluxes of ions and electrons between the energies of $40 eV and $45 keV. The database covers more than an entire solar cycle and all levels of geomagnetic activity. The derived flux averages and various percentile levels thus describe the environment to which geosynchronous satellites are exposed over their lifetimes and should provide a useful tool to guide satellite design and testing. The mission-averaged fluxes agree very well with other recent analyses in the energy ranges of overlap.

The key components in communications satellite payloads are the high-power amplifiers that amplify the received signal so that it can be accurately transmitted to the intended end user. In this study, we examine 26 amplifier anomalies and quantify the high-energy electron environment for periods of time prior to the anomalies. Building on the work of Lohmeyer and Cahoy (2013), we find that anomalies occur at a rate higher than just by chance when the >2 MeV electron fluence accumulated over 14 and 21 days is elevated. To try to understand "why," we model the amplifier subsystem to assess whether the dielectric material in the radio frequency (RF) coaxial cables, which are the most exposed part of the system, is liable to experience electrical breakdown due to internal charging. We find that the accumulated electric field over the 14 and 21 days leading up to the anomalies is high enough to cause the dielectric material in the coax to breakdown. We also find that the accumulated voltages reached are high enough to compromise components in the amplifier system, for example, the direct current (DC) blocking capacitor. An electron beam test using a representative coaxial cable terminated in a blocking capacitor showed that discharges could occur with peak voltages and energies sufficient to damage active RF semiconductor devices.

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The speed plasma propagates across a charged solar panel after a primary arc is one of the most important, yet poorly known, quantities in determining Electrostatic Discharge (ESD) currents for spacecraft arcing events. A review of the literature over the last two decades reveals that measured propagation velocity varies by as much as an order of magnitude. To overcome this deficiency, a round-robin set of tests was initiated with partners from industry, academia, NASA and the U.S. Air Force. This paper will provide the most recent results from the Air Force Research Laboratory testing conducted at the Spacecraft Charging and Instrument Calibration Laboratory.