Plasma Lens Focusing of an Intense Electron Beam formed by a Vacuum Arc Plasma Electron Source

This paper presents research results on focusing and transport of an intense (up to 100 A) nonrelativistic (up to 20 kV) pulsed electron beam using a positive space charge plasma lens. The electron source is based on electron extraction from the plasma of a hollow-anode vacuum arc discharge. The arc is initiated by a dielectric surface flashover. The emission hole is covered with a fine mesh grid. The beam is extracted and accelerated in a diode-type electron-optical system formed between the grid surface and an open anode plasma boundary. The anode plasma is produced in an electron beam transport channel by residual gas ionization by beam electrons and the plasma lens discharge. The plasma lens configuration of crossed electric and magnetic fields provides an attractive means for obtaining a stable low-pressure plasma discharge. This geometry allows compression of the electron beam from 6 cm to 1 cm in diameter with more than 100 A/cm(2) beam current density at the collector.