As part of the active phase of the AMPTE mission, clouds of neutral lithium and barium were released into the solar wind from the German Ion Release Module (IRM). In all cases the clouds ionize significantly in the first few seconds following the release, such that the solar wind flow is deflected. A magnetic cavity (field zero) is formed, but this is not associated with a total exclusion of solar wind protons. The close (~35 km for lithium, ~100--200 km for barium) proximity of another spacecraft, the United Kingdom Subsatellite (UKS), allowed good data coverage of the local environment. In the events the minimum Larmor radii of the solar wind protons is of the order of the size of the interaction region of the release; that of ''picked up'' release ions being one (lithium) or two (barium) orders of magnitude larger, which indicate the need for a hybrid description in which the release ions respond as particles to the magnetic field structures, supported by a charge-neutralizing electron fluid. We highlight important results from the data which, while invalidating a description using MHD theroy, are consistent with an ordering of the momentum transfer approximately along the local V B direction. We suggest that the existence of high proton flows in the interaction region requires a description which features at least two ion populations, and we show that this ordering may be predicted by treating the ions as a multi-fluid.