Author: Sudar, N.S.
Paper Title Page
TUP074 Results from the Nocibur Experiment at Brookhaven National Laboratory's Accelerator Test Facility 540
  • N.S. Sudar, J.P. Duris, I.I. Gadjev, P. Musumeci
    UCLA, Los Angeles, California, USA
  • M. Babzien, M.G. Fedurin, K. Kusche, I. Pogorelsky, M.N. Polyanskiy, C. Swinson
    BNL, Upton, Long Island, New York, USA
  Conversion efficiencies of electrical to optical power in a Free Electron Laser are typically limited by their Pierce parameter, ρ ~0.1%. Introducing strong undulator tapering can increase this efficiency greatly, with simulations showing possible conversion efficiencies of ~40%. Recent experiments performed with the Rubicon Inverse Free Electron Laser have demonstrated acceleration gradients of ~ 100 MeV/m and high particle trapping efficiency by coupling a pre-bunched electron beam to a high power CO2 laser pulse in a strongly tapered helical undulator. By reversing the undulator period tapering and re-optimizing the field strength along the Rubicon undulator, we obtain an Inverse Free Electron Laser decelerator, which we have aptly renamed Nocibur. This tapering profile is chosen so that the change in beam energy defined by the ponderomotive decelerating gradient matches the change in resonant energy defined by the undulator parameters, allowing the conversion of a large fraction of the electron beam power into coherent narrow-band radiation. We discuss this mechanism as well as results from a recent experiment performed with the Nocibur undulator at Brookhaven National Laboratory's Accelerator Test Facility.  
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