Defining Cryogenics

About the author…

Photo of John WeisendDr. John Weisend, currently the Board Chairman of the Cryogenic Society of America (CSA), is an expert in the field of cryogenics. He has worked on many cryogenic projects around the world at government and educational laboratories, serves as the editor of several cryogenic publications, has written books on cryogenics and related topics, and received numerous awards for his efforts. He has led the CSA Short Course Program since 2001, and is the instructor for CSA’s new webinar series.

What is Cryogenics?

Cryogenics is the science and engineering of extremely low temperatures. There is no formal fixed temperature at which cryogenics start; though many people use 120 K ( -243.67 ºF) as the upper end of the cryogenic region. This temperature is chosen as it is the point below which gases such as methane, oxygen, nitrogen, neon and helium start to become liquids. Some researchers use temperatures as high as 200 K ( -99.67 ºF) as the start of the cryogenic region.

While working at such low temperatures may seem to be of only academic interest; cryogenic temperatures enable many important technologies. These include the separation and distribution of atmospheric gases such as oxygen and nitrogen, the bulk transport of natural gas in liquid form (LNG), the cooling of superconducting magnets for MRI systems and basic physics research, the use of hydrogen and oxygen as propellants in space exploration and biological and medical applications. Worldwide, cryogenics is a multibillion dollar business.

Cryogenics should never be confused with cryonics about which more can be found here.

Dr. John Weisend II began writing his “Defining Cryogenics” for CSA’s Cold Facts magazine in 2009, continuing into 2018. The column explained frequently used cryogenic terms and is archived here to help readers understand this terminology. The columns have also been updated and gathered together with previously unpublished material in “He is for Helium: Defining Cryogenics from ADR to Zero Boiloff,” published by the CSA in 2018.