To reduce the quantity of liquid helium evaporation, we applied a pulse-tube refrigerator to the neck tube of a 1, 000-gallon liquid helium container. The contact spot of the pulse tube can be adjusted over a distance of 10cm to attain the optimum cooling point. The cooling performance of the pulse-tube refrigerator is the lowest operating temperature of about 50K and cooling power of 2W (at 80K) with power consumption of 700W. We have achieved a reduction in the liquid helium boil-off rate of 10%.
