Enthalpy—pressure (H-p) diagram of He3 in the range 1.0 K ≤ T ≤ 4.17 K and 0 ≤ p ≤ 6.5 atm and inversion curve for T ≤ 4.17 K

The enthalpy-pressure (H-p) diagram of He³ was determined by experiment. All important data for the operation of a continuous He³ refrigerator working on the Joule-Thomson principle can be derived from this diagram. In particular, the achievable refrigerating capacity at preselected operating conditions may be immediately ascertained. The inversion curve of He³ for T ? 4.17 K was determined from the H-p diagram and is in fair agreement with the data for T ? 4 K already known.