Beam injection and transport experiments with an upgraded injector in the UNM betatron
A study of the injection and transport of a high-power relativistic electron beam (130 A, 300 keV) in the UNM betatron was recently concluded. The electron beam was injected at an angle of 20 degrees with respect to the main axis of the accelerating ring. An electron beam current of 15 A was transported around the entire accelerating ring. The experiments verified that a transverse electric field can be used to bend an externally injected relativistic electron beam onto the main axis of the accelerating ring and that the injected beam can be transported in a periodic solenoidal lens array. The beam injection results were consistent with calculations of the single-particle orbits under the combined influence of a transverse electric field and a strong focusing magnetic field, as were used in the experiment. A large fraction of the electron beam current was lost during injection and transport. This is attributed to a large spread in beam energies that was caused by a nonuniform injector voltage pulse. In order to remedy this difficulty, the Marx generator is being upgraded to 600 kV and a novel crowbar system is being installed.<<ETX>>