From design and construction to operation of the APPLE undulator at TPS

Abstract

The APPLE type of Elliptically Polarized Undulator (EPU) not only serves as a crucial circularly polarized light source in existing accelerator facilities but also acts as a standard light source for soft X-rays at the Taiwan Photon Source (TPS). Up to the present, we have autonomously designed, constructed, and operated various EPU configurations. The experience gleaned from the construction of various designs and the choice of material will be outlined in this paper. We also elaborate upon the actions taken to address the adverse effects on the magnetic fields due to the characteristics of non-identical magnets and mechanical deformation. In particular, a method for correction of discrepancies in the magnetic field of the EPU with operation in numerous phase modes employing iron shims is described. In addition, we also discuss the adverse effects on the storage ring that must be dealt with for stable operation of the EPU at the TPS and optimization of the magnetic field during the laboratory construction phase. This paper will further explain management issues related to the susceptibility of the EPU to radiation damage. The comprehensive experience related to the EPU at the TPS, from design and construction to operation will be presented in this paper.