Electron-beam transport studies for radiographic applications

We have measured electron-beam-produced gas ionization in a paraxial-diode gas cell, using three different interferometric arrangements. We have also measured the beam net current at the channel wall. In the range of tens of kA/cm/sup 2/ and 0.3-5 Torr, the electron density is in the 10/sup 17/ cm/sup -3/ range, scaling strongly with beam current density and sublinearly with pressure. The fractional net current ranges from 20-40%. We are developing a rate-equation ionization model whose results are consistent with these measurements.