Hemispherical Electrostatic Analyzer

Description

A hemispherical electrostatic analyzer with a faraday cup collector was used to study the positive ion component of the solar wind in the energy range of 100 eV-15 keV. The sensor axis lay in the equatorial plane of the satellite. As the satellite spun, the instrument measured, in various longitudinal directions, particles incident within a few degrees of the satellite equatorial plane. Commanded changes in the spacecraft spin axis permitted determination of angular distributions in various planes. Operation was partial from August 27, through September 17, 1969, because the instrument was producing anomalous interference with the other instruments. The experiment was judged inoperable in March 1970.