| 摘要 |
1,228,029. Refrigerating. PHILIPS GLOEILAMPENFABRIEKEN N.V. 19 April. 1968 [22 April, 1967], No. 18674/68. Heading F4H. A load is continuously cooled by forcing helium II through a superleak to provide superfluid helium at the load. The heat generated by the load causes part of the superfluid to be converted to normal helium II and the resultant mixture of superfluid and normal helium is moved with a velocity exceeding its critical velocity either into, or into heat exchange with, a helium II bath to reject heat prior to further passage through the superleak. As illustrated, a dewar 8 contains a liquid helium bath which is maintained below the lambda point by evacuation. The bath surrounds an enclosure 6 which is evacuated through a connection 7. A closed liquid helium circuit is provided which comprises a pump 2, the superleak 3, a chamber 4 containing the load 11, and a duct 5 in which the helium exceeds its critical velocity. The bath may be at 1À3‹ K., the load may be at 0À7‹ K., and the superleak may be formed of carborundum or iron oxide. Since the duct portions are in heat exchange relationship with the bath, pressurized helium is presented to the superleak at the temperature of the bath, and the helium leaving the vacuum jacketed region at 12 rejects heat to the bath. In a modification, Fig. 2 (not shown), the helium circuit is not closed, and helium leaving the vacuum jacketed region is passed into the bath. The pump withdraws helium from the bath for passage to the superleak. |
