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  • Satellite Effects of Space Weather
  • Satellites and spacecrafts
  • Deep Dielectric or Bulk Charging

Deep Dielectric or Bulk Charging

  • This phenomenon is a problem primarily for high altitude spacecraft. At times, when Earth is immersed in a high-speed solar wind stream, the Van Allen belts become populated with high fluxes of relativistic (>~1 MeV) electrons. These electrons easily penetrate spacecraft shielding and can build up charge where they come to rest in dielectrics such as coax cable, circuit boards, electrically floating radiation shields, etc. If the electron flux is high for extended periods, abrupt discharges (tiny "lightening strokes") deep in the spacecraft can occur. High fluxes of these electrons vary with the 11 year solar cycle and are most prevalent late in the cycle and at solar minimum. Occasionally, high-energy electron events recur with a 27-day periodicity - the rotation period of the Sun. Discharges appear to correlate well with long periods of high fluxes. At these times, charge buildup exceeds the natural charge leakage rate of the dielectric. The charge builds and discharge occurs after the breakdown voltage is reached. In the past, some energetic electron enhancements at GEO have approached two weeks in duration. It was at the end of one of these long duration enhancements in 1994 that two Canadian satellites experienced debilitating upsets.

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