Interaction of an intense relativistic electron beam with preformed channels

The interaction of an intense relativistic electron beam (REB) with preformed channels in gaseous atmospheres has been analyzed in order to delineate the effects of reduced density, avalanche ionization, preexisting conductivity, and channel currents. The REB for these experiments was produced from a field emission diode driven by the ≈1.4 MV pulse from a pulse forming line. Relativistic electron beam currents up to ≈16 kA with current densities up to ≈2 kA/cm2 were achieved and the REB current was approximately a half sine wave of width 27 nsec (FWHM). Preformed channels in the atmosphere were created using laser‐guided electric discharges. Current‐carrying reduced density channels were produced by applying a second discharge to the reduced density channel produced by the first discharge. Reduced density (≤ρ0/80), nonconducting channels were produced by the absorption of radiation from a pulsed CO2 laser in ammonia gas at background pressures of ≈40 Torr (ρ0/20). The results show that reduced density had...