Supershort Avalanche Electron Beams in Discharges in Air and Other Gases at High Pressure

In this paper, the generation of supershort avalanche electron beams (SAEBs) from the plasmas of nanosecond diffuse discharges in air and other gases at atmospheric pressure was investigated. It is shown that, in the mode of SAEB generation, the plasma in the discharge gap with an inhomogeneous electric field can be produced in a time no greater than 100 ps with the charged-particle density sufficient to force out the electric field from the discharge-gap region occupied by the dense plasma. It is demonstrated that decreasing the voltage pulsewidth in the discharge gap (to ~100-ps FWHM) reduces the optimum gap for SAEB generation. It is also found that the difference in electron path toward the foil center and the foil edge affects the SAEB current pulsewidth. For lower voltages across the gap (~25 kV), the SAEB pulsewidth at half maximum is ~200 ps.