Power measurement for a sheet beam planar wiggler FEL amplifier

Summary form only given. The pulse power measurement for a sheet beam planar wiggler FEL (free-electron laser) amplifier experiment at UMCP (University of Maryland, College Park) is reported. The amplifier system consists of an EIO tube as power source, a waveguide taper, a miter bend, and a waveguide set in the wiggler. The EIO tube produces about 10 watts at 94 GHz. An antenna is set in the far-field region to pick up the radiation power from the open exit of the amplifier waveguide. The relation between the power picked up by the antenna and the total radiated power from the amplifier exit has been determined by calculations, based on far-field pattern analysis. Two different antennas were tested: a waveguide antenna at W-band and a horn antenna. It was found that the waveguide antenna is more efficient. Calibrations include tests of each part of the amplifier system and cold measurement of the whole system.