John Pfotenhauer co-directs the research activities in the Cryogenics Laboratory, and oversees the operation of the Liquid Helium / Nitrogen Facility. His research explores the development and application of refrigeration cycles, material properties, and thermal design all at low temperatures. Cryogenic refrigeration cycles, (cryocoolers) of particular interest include pulse tube refrigerators, mixed-gas Joule-Thomson refrigerators, and various hybrid coolers. Pfotenhauer also explores the integration of cryocoolers for cooling superconducting magnets and electronics, for processing and storing cryogens, and for space applications. He applies the fundamental principles of heat transfer, thermodynamics, and fluid dynamics to address the unique challenges that are encountered in these exciting low temperature applications.