| 摘要 |
Cryogenic cooling apparatus comprising an inlet path through which refrigerant gas is caused to flow, a Joule-Thomson expansion nozzle which communicates with the inlet path and in which, in use, a proportion of the refrigerant gas is caused to liquefy and an outlet path communicating with the outlet of the expansion nozzle, the inlet path being in heat exchange relationship with the outlet path. An elongate valve needle cooperates with the outlet side of the expansion nozzle and together with the latter constitutes a valve. A sensor is disposed in the space on the outlet side of the expansion nozzle and is arranged progressively to close the valve as the amount of liquid refrigerant in contact with it increases. The valve needle defines a bypass passage which extends along its entire length and remains open at all times. The apparatus is accommodated within a container, to the outer surface of a portion of the wall of which a thermal load is connected. The outlet end of the bypass passage is directed towards the portion of the container wall carrying the thermal load and thus ensures that the refrigerant in the vicinity of the said portion is maintained in a state of agitation at all times.
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