Design of vapour cooled shields of a superinsulated liquid helium dewar: theoretical analysis and experimental studies

摘要

In this paper, we present the theoretical analysis and predictions of these optimum positions of the vapour cooled shields, in MLI structure of a 100 litre capacity superinsulated demountable type liquid helium test cryostat, following the procedures of Bejan and Qingfu Li et al. The vapour cooled shields were cooled by the evaporating helium gas by connecting them at appropriate positions of the stainless steel neck tube, whose temperature profile is also predicted for the given evaporation rate. The paper presents the details of the experimental system along with the instrumentation for temperature measurements. The experimental results at steady state conditions such as evaporation rate of the cryostat, temperature profile of the neck tube and the superinsulation are presented.