Injection and drift studies of high current relativistic electron beams in a toroidal-like system

The successful use of an external field shaping cathode to inject high current relativistic E beams (500 kV, 20 kA, 50 nsec) across a toroidal magnetic field (1–4 kG) into a metallic vessel is presented. Injection of up to 50% of the diode energy into trajectories far removed from the metal wall (≳5rL) was achieved. Drift properties if the E beam in the toroidal vessel were studied. Energy fluence down the torus was measured. Up to 60% of the injected beam was recovered after propagating a distance of 8 m. The drift time around the torus was found to be long enough to enable trapping the beam in the toroidal system.