The Design and Testing of a Pre-cooling Helium Cryogenic Cryocooler for Compact Synchrotron

A project to develop core component for heavy-ion Synchrotron is underway in Lanzhou, having started in 2022. The aim of this project is reduced radius of the synchrotron by superconducting magnets. To cool the superconducting magnets of compact Heavy-Ion synchrotron, a pre-cooling helium cryogenic cryocooler is researched. The cryogenic system can generate over 10 watts cooling capacity at temperature of 4.5K. It adopts conduction pre-cooling with GM cryocoolers and is designed to be able to forced flow cooling superconducting magnets. To verify the process design and heat exchanger performance, an open circulation device with the same process as the designed model was built and a cooling test was carried out. As a result of the test, it was confirmed that the heat exchanger can achieve the designed heat transfer temperature. And it was also confirmed that there was a temperature gradient of about 5 K behind J-T valve between the measurement results and the thermal calculation results. The results of the present work shows that the open circulation system can realize rapid cooling and it has reference significance for the design of closed cycle cryogenic system. But there are some cooling process design needs further improvement in a later study.