6 cm period Apple-II type elliptically polarized undulator at PLS

Pohang Accelerator Laboratory is developing an Elliptically Polarized Undulator (EPU6) to utilize the polarized synchrotron radiation at Pohang Light Source (PLS). EPU6 is an Apple-II type elliptical undulator which changes the polarization of the field by translating the magnet arrays. EPU6 features period of 6 cm, minimum gap of 19 mm, 25 full field periods, maximum vertical flux density of 0.69 T, maximum horizontal flux density of 0.45 T, and 1575 mm total magnetic structure length. In this article, the design, fabrication, the measurement and correction efforts for PLS EPU6 undulator are described.