This paper analyzes the plasma characteristics measured in the dusk sector of the plasmasphere during the period May--June 1982, mainly by the satellites De 1 and GEOS 2, in order to examine the hypothesis of a lack of connection between the equatorial plasmaspheric bulge and the underlying ionosphere. The orbits of the spacecraft allow a study of the dusk bulge from two different perspectives: GEOS 2, geostationary, yields the local time variations of the plasma parameters, whereas De 1 stays roughly in a meridian plane and provides their latitudinal variations. Different techniques (waves and ion spectrometer in the very low energy range) are used and compared. A period of a few days (May 22--26) is analyzed in detail. Large density irregularities are commonly observed, as well as significant plasma drifts, but the bulge does not seem to be limited in latitude, at least between +40 and -40 degrees magnetic latitude. The analysis of the plasma distribution along a field line shows the existence of different plasma regimes, depending on the geophysical conditions encountered. In particular, we have observed (1) during the replenishment of depleted flux tubes, an apparent accumulation of plasma at about 3 earth radii and 40¿ latitude, and a double field-aligned regime in the equatorial region, and (2) under conditions of moderate magnetic activity, the appearance of a high density region, with origin presumably in the inner plasmasphere, extending to geostationary orbit. In this region of L=4.6 to 6, the density, normalized to the volume of the flux tubes, is constant over the latitudinal range explored (from minus to plus 40¿), as expected from a diffusive equilibrium distribution.