Magnetic field integral measurements with stretched wire and Hall probe methods

In this article, we analyze magnetic measurements on the U50-II undulator. The U50-II undulator is a 50 mm period length NdFeB-based pure permanent-magnet undulator prototype. It is designed with 20 periods and delivers 0.88–0.17 T in the gap from 10 to 35 mm. The field integrals are measured on a Hall probe bench, and the measurements are compared with the stretched wire result. In the stretched wire setup, the field integral is measured with an accuracy of 2 mTmm. The details of the stretch wire probe setup, measurement procedure, and accuracy with Hall probe results are discussed.