Development of liquid helium-free cryostat for a superconducting undulator

The superconducting undulator (SCU) is a type of insertion device with great development potential. SCU can generate higher peak field than permanent magnet undulator at the same period length and vacuum gap. In the early stage of SCU development, it is necessary to test various winding schemes and coil parameters. A reliable cryogenic system is the precondition for superconductivity. To test SCU short prototypes in a compatible way, a convenient low-temperature platform is in high demand. In addition, due to the high cost and unpredictable availability of liquid helium, a helium-free platform is beneficial. In this paper, a successful low-temperature platform for the SCU short module test is introduced. It is compatible with different coil structures. Comprehensive design ingredients, such as the current leads, cold mass, thermal shield, etc., are described in detail. The platform performances in the module test are recorded and analyzed as well. The cold mass was cooled to about 2.9 K, and the maximum current of the superconductor was approximately 500 A.