Temperature inhomogeneity in high capacity pulse tube cryocoolers

Abstract

High power pulse tube cryocoolers are expected to be a very promising candidate for high temperature superconductors (HTS) cooling. Unfortunately there are still some problems significantly deteriorating the performance of these cryocoolers, one of which is temperature inhomogeneity. Several different theories have been proposed to explain the mechanism and many factors have been indicated as contributors to the generation and development of temperature inhomogeneity. However, some relations between these factors are seldom noticed, nor classified. The underlying mechanisms are not yet clear. The paper classifies, as internal and external, factors leading to temperature inhomogeneity based on their location. We examine some apparently unreasonable assumptions that have been made and difficulties in simulation and measurement. Theoretical and experimental research on the driving mechanism and suppression of temperature inhomogeneity is reviewed, and potential analysis and measurement methods which could be used in future are identified.