Dr. Peter Shirron, a senior research scientist with NASA’s Cryogenics and Fluids Group, led the team of researchers credited with developing the first continuous duty multi-stage adiabatic demagnetization refrigerator (ADR) used to cool sophisticated space-borne detector arrays to temperatures below 2 Kelvin.
NASA Tech Briefs: You have a PhD in low-temperature physics. How does the science of low-temperature physics differ from that of conventional physics?
Dr. Peter Shirron: Well, the physics that governs matter is the same in all environments. But many of the most exciting physical phenomenon – and for me those are the ones that are based on quantum effects – usually can be observed only when you’re dealing with atomic-size scales, or when things are at very low temperatures.
Most people have heard of superconductivity, where electricity can be conducted with zero resistance, but there are also phenomena such as superfluidity, where liquid helium can flow with zero viscosity, and there are changes of state where gases like air, that we usually only experience in the gas phase, turn from liquid to solid as you go cold. There are also structural phase transitions and magnetic transitions that occur as materials are cooled, as well as a lot of just basic changes in dimensions, strength, electrical properties, that can be very pronounced and very useful. So as I said, while the physics are the same, there are a lot of different effects you see as you cool things down that make cryogenics a real exciting field for me.
NTB: You work as a research scientist in NASA’s Cryogenics and Fluids Group. What, exactly, is cryogenics?
Shirron: In short, cryogenics is the study of materials at, and the production of, very cold temperature. It concerns both the refrigeration techniques that allow you to get down to very low temperature, and the knowledge and study of how materials change, different phenomena that crop up, and ways that those can be used in different situations to achieve a lot of different goals. As I said, superconductivity is the big one so, for example, knowing where things transition to the superconducting state, knowing what will destroy that state, knowing the properties of superconducting materials, is all part of what we consider to be cryogenics.