DEVELOPMENT OF AN ELECTROMAGNETIC HELICAL MICROWIGGLER WITH PERMANENT-MAGNETS

An electromagnetic helical microwiggler with three poles per period, e mploying permanent magnets to suppress leakage flux in the vicinity of the gap, has been developed, The wiggler is embedded in a double-wall ed vacuum chamber with a water jacket for heat removal, The field prof ile consists of a 30-period-long uniform-field section terminated at b oth ends with 5-period-long tapered fields. A peak on-axis field of 3. 0 kG was achieved with a period of 7.9 mm and a gap diameter of 4.6 mm , An optimal sorting technique was applied to the permanent magnets to minimize variations in the peak field amplitude. Based on measurement s of the test wiggler, rms amplitude variations of 1.4% and 2.6% in, r espectively, the horizontal and vertical field amplitudes were attaine d.