E-Mail IMAGE: 4 K pulse tube cryocooler developed by researchers at the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences view more Credit: Liubiao Chen/University of Chinese Academy of Sciences WASHINGTON, April 6, 2021 -- Cryocoolers are ultracold refrigeration units used in surgery and drug development, semiconductor fabrication, and spacecraft. They can be tubes, pumps, tabletop sizes, or larger refrigerator systems. The regenerative heat exchanger, or regenerator, is a core component of cryocoolers. At temperatures below 10 kelvins (-441.67 degrees Fahrenheit), performance drops precipitously, with maximum regenerator loss of more than 50%. In their paper, published in Applied Physics Letters, by AIP Publishing, researchers at the University of Chinese Academy of Sciences used superactivated carbon particles as an alternative regenerator material to increase cooling capability at temperatures as low as 4 kelvins.