Operating Experience with MUSL-2

The second 6 pass microtron using a superconducting linac has been completed and has operated on 24 hour schedules for nuclear physics for about 5000 hours during the past year. The Q of the linac has remained at 3x109 and the C.W. energy gain has remained at 2.3 MeV/m as in its initial tests in 1975. Single pass C.W. currents up to 20 ¿A with energies up to 14.6 MeV have been available for resonance fluorescence experiments. Six pass beams with energies up to 67 MeV have been available to other experimental areas but useful currents have been limited to 0.3 ¿A by the excitation of transverse beam blowup modes around 2.3 GHz. The multiple pass currents, however, have been more than sufficient for all tagged photon experiments. Work is proceeding to replace our MUSL-2 linac with another Stanford linac in which the loading of the 2.3 GHz modes is increased by a factor of 100 or more by hybrid electric-magnetic loading probes. Plans to reach higher energies by using MUSL-2 as an injector into a second microtron continue to be attractive.