Cryogenic System for the Integration of a Ring-Shaped SMB in a Ring-Spinning Tester

A liquid nitrogen cryostat has been developed for experiments with a Superconducting Magnetic Bearing (SMB) in a ring spinning machine. The use of an SMB without friction instead of the common friction afflicted twist element is a promising approach leading to increased productivity and material variety. Here, an SMB designed as an axial ring system consisting of a liquid nitrogen (LN2)-cooled high-temperature superconductor ring YBa2Cu3O7-x and a permanent-magnet ring at room temperature is investigated. To assure the high quality of the yarn, the process has strong edge conditions concerning the air moisture and the ambient temperature. To protect the yarn from LN2 temperature, a continuous-flow cryostat was designed, tested, and integrated in the ring spinning tester. The geometric requirements of the spinning process lead to a ring-shaped vessel with a hole in the middle for the rotating spindle. First spinning experiments running at rotations in the range of 20 000 rpm show a reliable operation of the continuous flow cryostat in the SMB-based spinning process. In addition, easy process handling and low LN2 consumption are demonstrated.