High-current electron beam formation in an explosive emission diode at ∼10/sup -2/-10

Abstract

The duration of electron beams generated in an explosive-emission diode at a /spl sim/10/sup -2/-10/sup -1/ torr gas pressure is equal to /spl sim/10/sup -8/ s and is limited by the breakdowns resulting from the filling of the interelectrode gap with plasma. The paper presents data on the production of high-current electron beams in an explosive-emission diode in the above pressure range as well as results of an investigation of the possibility to increase the beam duration. The experiments were carried out on an electron source with a high-voltage vacuum lead that prevented the initiation of a gas discharge at the nonemitting cathode regions and at the cathode holder. To slow down the decrease in diode impedance, the emitting surface of the cathodes was made of materials characterized by a low rate of plasma production. It has been shown that if the electric circuit power is high enough, the duration of the high-voltage discharge stage can be substantial. At a /spl sim/200 kV diode voltage, the discharge regimes with a high-voltage stage duration of up to 800 and 80 ns at a residual gas pressure of 10/sup -2/ and 10/sup -1/ torr, respectively, have been realized. The high-voltage stage current has been established to be completely transferred by the electron beam. This current reached /spl sim/10/sup 2/ A and higher values. The duration of the electron beam that had passed through a 50-/spl mu/m thick Ti foil was /spl sim/200 and 40 ns at a 10/sup -2/ and 10/sup -1/ torr pressure, respectively, and was limited by the foil transparency.