Phasor Analysis of Two-stage Gm-type Pulse Tube Refrigerator

A two-stage pulse tube refrigerator (PTR) is the simplest version of a multistage pulse tube refrigerator. A two-stage Gifford-McMahon (GM) has been used for nearly all of the cryopumps. The phasor analysis of the Gifford-McMahan (GM)-type pulse tube refrrigerator (PTR) have not explained detail in the earlier study. In the present work, a detailed mass flow, enthalpy & phasor analysis for a two-stage PTR, both for OPTR and DIPTR has been studied. The phasor analysis helps to understand the importance of phase difference between mass flow rate at the cold end and the pressure pulse in the pulse tube. The refrigerating effect for different types of PTR strongly depends on the phase shift arrangement and also on the phase difference. Due to the complexities of the flow involved in the two-stage, the phasor diagram will prove to be very helpful to understand the importance of these parameters. It also introduces the concept and importance of phase lead of the double inlet flow entry in the OPTR & DIPTR.