Implementation of PLTS-2000: He-3 Melting Pressure Temperature Scale

摘要

The recently adopted PLTS-2000, which extends the temperature scale to 0.9 mK, is defined by the melting pressure of ~3He and various fixed points on the melting curve. Because of the minimum in P(T) at 315 mK, pressures at lower temperatures must be measured with an in situ transducer. In this paper, the equipment necessary for producing melting helium and measuring the pressure are described. This includes the Straty-Adams capacitive pressure transducer, the bridge for measuring capacitance, and the ~3He gas handling system. Procedures for calibrating the pressure transducer and for observing the various fixed points established in PLTS-2000 are presented.