We described a method for correcting the magnetic field of a superconducting undulator with neutral poles. For correction, the main windings of the undulator are used, grouped into separate groups and powered by additional currents. Graphs of phase errors are presented for the entire range of magnetic fields of the undulator after correction. The magnitudes of the total and local phase errors were 3.5 and 1.9 degrees for a maximum field of 1.2 T.
Kanonik et al. (Wed,) studied this question.