Transport of long-pulse, high-current electron beams in preformed monoatomic plasma channels in the ion focus regime

Experiments have been performed demonstrating the efficient transport of long-pulse, high-current electron beams in well-diagnosed, preformed plasma channels. Channels were created by the low-energy electron-beam ionization of low-pressure monatomic gases. These transport efficiencies are comparable to the optimum values obtained for similar pulse lengths in previous long pulse, electron-beam transport experiments in laser-preionized diethylaniline gas. Experimental results show the development of both transverse current centroid oscillations characteristic of the ion hose instability and the microwave emission indicative of relativistic electron beam-plasma electron two-stream instability. Significant microwave emission indicating rapid growth of the two-stream instability has been observed in the S-band when the space-charge neutralization fraction f_e exceeds unity