High current, low energy electron beams produced during the high current phase of a pseudospark

Electron beams produced by the superemissive cathode of a back-lighted thyratron (BLT) or pseudospark are reported. The cathode is highly emissive, or superemissive during conduction, producing a current density of >104 A/cm2 over an area of ∼1 cm2. During conduction, electrons produced by the cathode are accelerated through the anode central hole, forming a beam that can be extracted. An electron beam of 120 A has been observed with an efficiency of 10%. The beam current increases with increasing applied voltages and decreasing gas pressure. A pulse forming network can transfer energy to an electron beam with a duration of the discharge pulse. The superemissive beam has energy of ∼400 eV corresponding to the cathode sheath voltage. Beam extraction into a low pressure area (<7 mTorr) was achieved by a differential pumping scheme with a guiding magnetic field. A flat-top spatial profile of the beam current distribution is obtained after the beam propagation through a narrow dielectric tube