Development of Indigenous Technology for Large Cooling Capacity GM Cryorefrigerator for Application to High Tc Superconducting Magnets—Prospects and Problems

Superconducting magnets have traditionally been used in MRI medical diagnostic equipment, particle accelerators and a variety of industrial applications. Although most magnets made in our country so far have used low Tc superconductors operating at liquid helium temperatures, there is a distinct possibility that magnets of tomorrow will be made of high Tc materials that offer zero resistance around the temperature of liquid nitrogen (77 K). The optimum temperature for operating these magnets will be around 40–50 K, which is achievable by using GM-type cryocoolers. Unfortunately, in spite of nearly a century of experience in cryogenic technology, our country continues to import basic cryogenic cooling equipment. It is time for taking up indigenous development of such important and easy-to-achieve equipment. We are happy to report that such a development project has been taken up by the authors at the C. V. Raman College of Engineering, Bhubaneswar. The target of the development project is to design and build a GM-type closed-cycle cryocooler delivering about 100–150 W of refrigeration at 45 K. The paper presents the design methodology and means of construction. The complete design, fabrication and testing process are being documented so that other workers in India, both researchers and entrepreneurs, can build their own systems and even improve on our design, without additional help from any quarter. The objective of the present activity is to develop the complete end-to-end indigenous technology so that a techno-entrepreneur can initiate a business start-up basing on our experience and our recommendations..