spase://SMWG/Instrument/Explorer35/FaradayCup

A multigrid, split-collector Faraday cup mounted
on the equator of the lunar-orbiting Explorer 35 spacecraft was used
to study the directional intensity of solar wind positive ions and
electrons with particular emphasis on the interaction of the solar
wind with the moon. Twenty-seven integral current samples (requiring
about 4.3 s) were taken in an energy-per-charge window from 80 to 2850 eV.
Then the current was sampled in eight differential energy-per-charge windows
between 50 and 5400 eV at the azimuth where the peak current appeared
in the previous series of integral measurements. These measurements
(integral and differential) took about 25 s. Both the sum and
difference of collector currents were obtained for positive ions.
Only the sum was obtained for electrons. A complete set of measurements
(two collector plate sums and one difference for protons, and one
collector plate sum for electrons) required 328 s. The experiment
worked well from launch until its failure in July 1968. For further
details, see Lyon et al., J. Geophys. Res., v. 72, p. 6113, 1967.