A novel effective suppression of natural convection in pulse tube coolers

Abstract: Due to natural convection, the cooling performance of the pulse tube cooler (PTC) greatly degrades if the pulse tube cold-head is placed upward. In our previous study, it was found that the natural convection in the pulse tube can be well suppressed by inserting a certain number of circular screens. In this paper, a further detailed investigation into this suppression method are made, including the effect of number and material of screens, input acoustic power, and some other factors on suppressing natural convection at different inclination angles θ in the range of 0–180°. In our experiment of a single stage inline type PTC driven by a linear compressor, the orientation-dependence is considerably weakened with 6-layer copper screens in the pulse tube, in the cold temperature range of 40–80K. Moreover, the cooling performance deterioration at θ =0° induced by the inserted screens can be kept in an acceptable range. This novel suppression of natural convection greatly improves adaptability of pulse tube cryocoolers’ application. [ABSTRACT FROM AUTHOR]