CONJUGATED FLUXES. “Conjugate photoelectron fluxes observed on Atmosphere Explorer C. The magnitude of the observed conjugate photoelectron flux varies considerably between passes, but in some cases the 250 km flux has been observed to be as much as half of the magnitude of the escaping photoelectron flux at 300 km near the sunlit conjugate point.”
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/GL004i003p00109