Response of geostationary communications satellite solid-state power amplifiers to high-energy electron fluence

Abstract

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.

Space Weather: Historical and Contemporary Perspectives

“…Radiation can also cause components on satellites to become radioactive. Errors will be induced in computer logic systems and solid-state memories (e.g., Lohmeyer et al 2015;Clements et al 2016). Radiation will induce false signals in scientific optical instruments and in sun and star trackers that are used for spacecraft attitude control (Birnbaum 1996).…”

Telemetry Fault-Detection Algorithms: Applications for Spacecraft Monitoring and Space Environment Sensing

“…Because of the proprietary nature of the telemetry and the spacecraft from which the telemetry originates, we cannot comment on the precise We compare the high-energy electron fluence accumulated before the largest events. Build up of high-energy electrons can lead to charging of dielectric materials, potentially causing catastrophic discharges [44,45]. Comparing the fluence accumulated 1, 7, 10, 14, and 21 days before the large-event dates to a random Monte Carlo sampling of days, we find no statistically significant relationship between accumulated fluence and the events detected by the algorithms [45].…”

Space Weather Quarterly Volume 14, Issue 3, 2017

“…Solar cells will also slowly lose effectiveness in converting sunlight to electrical power due to damage by continued irradiation. Energetic ion radiation impinging on internal insulating materials and on solar arrays can cause electrical discharges if the charge buildups in the insulators become sufficiently large [Lanzerotti et al, 1998b;Lohmeyer and Cahoy, 2013;Lohmeyer et al, 2015]. Energetic protons and heavy ions from trapped radiation, solar particle events, and cosmic rays can cause logic upsets in satellite semiconductor memories and computers.…”

“…While the study is thorough and informative, it cannot be used to predict current or future problems since serious issues are often remedied with improved design strategies and new technologies. Two studies, [Lohmeyer and Cahoy, 2013;Lohmeyer et al, 2015], provide a more recent example of space weather related issues. These papers suggest that failures of Solid State Power Amplifiers (SSPAs), on one of the Inmarsat satellite fleets could be related to internal charging from high-energy electrons.…”

“…Energetic electrons accumulate in interior dielectrics (circuit boards or cable insulators) and on ungrounded metal (spot shields or connector contacts) leading to electrical breakdown in the vicinity of sensitive electronics [e.g., Fennell et al, 2001;Lohmeyer et al, 2015]. Single Event Effects (SEE).…”