• A. Knyazik, J.B. Rosenzweig, R. Tikhoplav
  UCLA, Los Angeles, California

A helical undulator, utilizing permanent-magnet of cylindrically symmetric (Halbach) geometry has been developed at UCLA’s Neptune Facility. The initial prototype is a short 10 cm, 7 periods long helical undulator, designed to test the electron-photon coupling by observing the micro-bunching has been constructed and is currently being tested in the Neptune facility. An Open Iris-Loaded Waveguide Structure (OILS) scheme which conserves laser mode size and wave fronts throughout the undulator, is utilized to avoid Gouy phase shift caused by focusing of the drive laser. Coherent Transition Radiation and Coherent Cherenkov Radiation is used for micro-bunching diagnostic. Currently the undulator has been built, magnets were calibrated via pulsed wire method.