Electron Beam Transport Experimts with Short Duration Pulses

This paper describes experiments designed to extend the simulation of IEMP effects by fast pulse (<5 ns) electron-beam techniques, to larger areas (>700 cm2) and greater total currents (~9 kA) than heretofore. Both charge and current neutralization as a function of pressure from <10-2 mTorr to 700 mTorr were determined with an electron-beam facility that generated an injected pulse with rise time ~l.5 ns and a peak intensity of 12.5 A/cm2. The results indicate that for such large time rate of change of total currents, the necessary pressure to achieve space-charge barrier dissipation before the peak of the pulse will also lead to avalanche breakdown of the ambient gas, occurring at almost the same time and thus reducing the net transmitted current.