Formation of high-current electron beams in dense gases

Subnanosecond electron beams with the record current amplitude (~70 A in air and ~200 A in helium) were produced at the atmospheric pressure. The optimal generator open-circuit voltage was found for which the electron-beam current amplitude produced in a gas diode was maximal behind a foil. It was established that electron beam was produced at the stage when the cathode plasma closely approaches anode. It was shown that a high-current beam can be produced at high pressures because of the presence of the upper branches in the curves characterizing the electron-escape (runaway) criterion and the discharge-ignition criterion (Paschen curve).