[en] The next generation of radiographic machines based on induction accelerators is expected to generate multiple, small diameter x-ray spots of high intensity. Experiments to study the interaction of the electron beam with the x-ray converter are being performed at the Lawrence Livermore National Laboratory (LLNL) using the 6-MeV, 2-kA Experimental Test Accelerator (ETA) electron beam. The physics issues of greatest concern can be separated into two categories. The multiple pulse issue involves the interaction of subsequent beam pulses with the expanding plasma plume generated by earlier pulses striking the x-ray converter. The plume expands at several millimeters per microsecond and defines the minimum transverse spacing of the pulses. The single pulse issue is more subtle and involves the extraction of light ions by the head of the beam pulse. These light ions might propagate at velocities of several millimeters per nanosecond through the body of the incoming pulse resulting in a moving focus prior to the converter. In this paper we describe Faraday cup measurements performed to quantify the plasma plume expansion and velocities of light ions