IFR guiding experiments

We have developed a new technique for electrostatically guiding high-current electron beams in accelerators and for IFR (ion focused regime) propagation experiments. The new method allows transport of IREBs over curved paths for applications in circular accelerators such as Sandia's recirculating linac. This method uses a low-energy electron beam in place of a laser to ionize the channel and thereby allows the use of any background gas desired instead of being restricted to the use of organics with high-photoionization cross sections. A weak longitudinal magnetic field is applied to confine the low-energy beam, enabling one to precisely define the ionization channel. Using this method, we have guided a 1.2 MeV beam with currents exceeding 20 kA over a 3-m straight path. In these experiments with high nu/..gamma.. beams, we observed the inductive erosion and also studied the effects of ion mass on channel stability. Both effects can be important for accelerator applications. The transport of high-current beams around a 90/sup 0/ bend is described in a companion paper. 8 figs.