An off-axis 50-period electromagnet wiggler for millimeter-wave free-electron laser experiment

An off-axis 50-period planar, short-wavelength (/spl sim/10 mm) electromagnet wiggler is developed and characterized for millimeter-wave generation using a sheet electron beam in a free-electron laser experiment. Three-dimensional (3-D) magnetic field measurements of the electromagnet wiggler have been carried out. The measured wiggler magnetic field is 0.16 G/A /spl plusmn/3% while the mean value of wiggler wavelength is 0.998/spl plusmn/3% cm. Due to off-axis arrangement of poles, there is a magnetic mirror field in the X direction, to confine the sheet beam.