Quadrispherical LEPEDEAS for ISEE´s-1 and -2 Plasma Measurements

A new generation of spaceflight instrumentation for comprehensive measurements of plasmas within the earth´s magnetosphere and its environs is described. These quadrispherical low energy proton and electron differential energy analyzers (LEPEDEAS) for the ISEE´s-l and -2 spacecraft are capable of determining the directional intensities of positive ions and electrons over all but 2 percent of the 4¿ sr solid angle for charged-particle velocity vectors at the spacecraft positions. The energy range of this instrumentation is 1 eV < E/Q < 45 keV with good energy and angular resolutions. An example of inflight observations within the earth´s magnetosheath is presented.