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 4π 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.