Experimental Investigation of Superconducting Linear Compressor (SCLC) for Pulse Tube Refrigerator (PTR)

This research paper focuses on the development of the Stirling-type pulse tube refrigerator (PTR) system. The system includes an innovative cold compression concept by introducing a superconducting linear compressor (SCLC). As one of the key goals of this research, the working gas (helium) is to be compressed directly at cryogenic temperature. The mechanical work (pressure-volume (PV) work) can be directly transmitted to the PTR system without experiencing precooling process. The unique feature of this paper is to utilize a high-temperature superconductor (HTS) coil instead of using metallic conductor coil for a linear motor. By implementing a HTS linear motor to the cold compressor, the ohmic loss can be inherently eliminated, so that the higher motor efficiency can be expected. In this research paper, the experimental validation as a proof of concept is carried out. The HTS linear motor operates at 50 Hz without creating overheat problem. The SCLC stably generates the PV work at the temperature of liquid nitrogen and it is subsequently transmitted to the compression volume of the PTR. The whole PTR system, therefore, can readily operate between 80 and 20 K with the cooling capacity of 0.26 W.