Transport of relativistic electron beams along wire arrays

Summary form only given, as follows. Theoretical predications and particle simulations have been tested which indicate that an array of longitudinal wires provides charge and current neutralization of a relativistic electron beam. This allows beam propagation above the drift tube limit without requiring an external magnetic field. A 60 ns, 17-kA pulse of 1.4-MeV electrons was injected into an array of 1-m-long wires with a 1-cm spacing, filling a hexagon 15 cm across. Arrays were tested with stainless steel and copper wires with diameters of 3 and 1.6 mil. Also tested were arrays with wires terminating on an insulated, segmented beam dump. The data show good transport (up to 90%) of the injected current. These results contrast with earlier experiments using 12-mil wires in which transport was cut off after the initial 10 ns. The arrays constructed with insulated beam dumps showed better transported beam profiles, with less beam pinching, than the other arrays. Particle simulations correlate well with these experiments and provide an understanding of the effect of scattering by wires on transport and beam quality. Microwave generation was also observed (≈0.5 W/cm² between 5 and 20 GHz)