Experiments on insulation of relativistic electron flows in oblique magnetic fields

Abstract

Several experiments on magnetically insulated electron flows are reported. These include experiments in combined axial and azimuthal magnetic fields like those seen in powerful ion diodes, and flows in which the degree of insulation is changed along the flow path. Conservation of transverse electron canonical momentum implies that the flows cannot be exactly in the E*B direction. Measurements of the field pitch (the ratio of the axial to the azimuthal magnetic field) show a tendency to flow in the E*B direction with very little current along the magnetic field. However, it was also found that the flow tended to find an equilibrium where electrons in the E*B flow have only small transverse canonical momentum. Other data show a surprising degree of electron recapture at the cathode under some conditions. This has important implications for multiterawatt devices.