Measurements of resistive hose detuning in intense relativistic electron beams

Abstract

Summary form only given. An intense relativistic electron beam injected into dense gas characteristically propagates in a self-pinched mode but is susceptible to the resistive hose instability. This instability typically leads to large amplitude beam motion and the disruption of propagation. Theory and computation suggest that although resistive hose cannot be completely suppressed, its convective growth can be reduced by increasing the average betatron oscillation frequency from head to tail in the beam pulse. In the experiment, a passive ion-focused regime (IFR) cell is used to condition a 5 MeV, 10-20 kA, electron beam produced by the SuperIBEX accelerator. Emittance tailoring is primarily controlled by adjusting the injected beam current and emittance and the IFR cell pressure, geometry, and output foil thickness. At the cell output, beam current, net current, and beam radius are measured, /spl eta/(/spl tau/) is evaluated, and conditioning effectiveness assessed. The beam is subsequently injected into a 2 meter diameter propagation tank. Beam propagation stability is studied by using time resolved optics, open shutter cameras, and net current probe arrays. Beam conditioning and propagation measurements are presented and the results of the experiments are discussed in relation to theory and simulation.