Operational experience with resonantly extracted beams

The MIT-Bates Linear Accelerator has completed a major nuclear physics experiment using high duty factor electron beam resonantly extracted from the South Hall Ring. Average currents up to 8 /spl mu/A at energies from 569 to 950 MeV were delivered to the new Out Of Plane Spectrometer System, with typical duty factors of 60%. Throughput efficiencies, measured as the ratio of beam current injected into the ring to that delivered to experiment, were 80-90%. The extraction process was repeated at a 600 Hz repetition rate, giving storage times much shorter than the beam damping time. Thus, beam dynamics were exclusively in a transient state. Details of the operational experience, including important aspects of beam set-up, on-line monitoring, and maintenance, are presented.