Comparison of results of explorer XXXI direct measurement probes

Intercomparison measurements of the major ionospheric parameters of ion and electron density and temperature and ionic species made by direct measurement probes on the Explorer XXXI satellite are presented. Plasma density results are compared with simultaneous data from the Alouette II satellite. Probe results are from the following experiments: planar ion trap, planar electron trap, cylindrical electrostatic probes, high resolution magnetic ion mass spectrometer, planar Langmuir plate, and spherical ion probe. The plasma densities measured by the various probes generally agree with simultaneous Alouette II sounder values to within 20 percent. Electron temperatures measured by three different types of probes generally agree within 10 percent. Ion composition measurements by the planar ion trap and spherical probe show good agreement with the high resolution magnetic mass spectrometer. Ion temperature measurements from the ion trap are consistently higher than spherical ion probe results.