Describes the measurements made with differential particle detectors in a laboratory 'ionospheric' plasma. The plasma in the ionospheric plasma facility of the Centre de Recherches en Physique de l'Environment Terrestre et Planetaire (CRPE) plasma physics group at Orleans, France, was investigated with suprathermal plasma analysers (SPAs) identical to those flown by the Mullard Space Sci. Laboratory (MSSL) on the ESA GEOS satellites.