Design Improvement of a Staggered YBCO Undulator

A strong field and short period undulator can be a desirable light source device in a storage ring or a free-electron laser. Bulk YBCO can be used to construct a high-temperature-superconducting undulator in a staggered array structure. The YBCO material in form of 32 mm diameter and 2.5 mm thick was used to assemble a staggered magnet array. The period length is 5 mm and the magnet gap is 4 mm. To estimate the strength of a sinusoidal field and to optimize the end-pole design to minimize the first (i.e., electron angle) and second field integral (electron position), an energy-minimization method (EM-method) based on Bean's model to simulate the field trapped in the HTS-Block is introduced. In this paper, we focus on promoting the practical value of the EM-method simulation. Combining the experimental experience of a YBCO staggered undulator and the simulation experience based on the EM-method, we address some issues to enhance the efficacy of this undulator design.