Transport of a large-current microsecond electron beam in a neutral gas

Experiments were conducted on the transporting of a microsecond electron beam through a low-pressure neutral gas. Experiments were carried out in a coaxial-cathode device with drift tube anode at a neutral gas pressure of 0.1-0.2 mtorr. The beam was transported from the cathode 32 cm to the Faraday cylinder with a delay of about 1.6 microsec. When the transport length was increased to 83 cm the delay time was 2.7 microsec. Although the transport efficiency is not great, the current transported through the drift tube under conditions of partial charge neutralization is still several times greater than the limiting vacuum current for the same geometry with beam focusing by an external magnetic field.