Abstract: A portable low-noise cryogenic system based on Stirling-type co-axial pulse tube cryocooler (PTC) for cooling HTc SQUIDs is designed and systematically tested. All components of the PTCs in the vicinity of SQUIDs pick-up loops are made of non-magnetic and non-metallic materials to eliminate complicated interference and realize direct couple with SQUIDs. The selections of the materials for the PTCs, the design and optimization of the system are described in detail, and the analysis and evaluation of the performance are presented. The preliminary experiments indicate that the cooling performance and interference characteristics of the system meet the basic requirements.

Key words: Cryogenic system, HTc SQUIDs, Stirling-type pulse tube cryocooler