Experience in Recirculating Electrons through a Superconducting Linac

An electron beam of several microamperes has been accelerated by a 6 foot 1.3 GHz superconducting niobium linac to 3.5 MeV on its first pass. It has been returned to the linac for two additional passes with energy gains around 3 MeV per pass to a final energy of 9.5 MeV. The recirculation is accomplished by means of two uniform field magnets placed at each end of the accelerating section in a racetrack microtron geometry which will accommodate the return beams for six passes through the linac.