US 4,228,662 A · Cryogenic apparatus

Abstract

A cryogenic apparatus cools an object to, and maintains it at, very low terature and is of the kind in which a refrigerating medium comprising superfluid helium II is evaporated from a supply container into an evacuable exhaust system through a throttle element. Such element includes a valve comprising a valve element displaceable relative to a valve sleeve, and the element and sleeve define a passage gap which, in the normal control range, has a width of less than 10 .mu.m and a length determined by the position of the element relative to the sleeve. Such valve may have an additional control range in which the width of the passage gap is greater than 10 .mu.m. The valve element may be a cylindrical plunger which is axially movable within the sleeve and which defines with the sleeve over at least part of its movement an annular gap having a width less than 10 .mu.m. The apparatus may include a regulating means which controls the position of the plunger according to the temperature of the object and also at least one heat exchanger arranged in the exhaust system which is positioned either in the supply container or adjacent the object.

Claims12

Dependent claims

A cryogenic apparatus for cooling objects to and maintaining them at very low temperatures by the evaporation of superfluid helium II using confinement produced by the thermomechanical effect, said apparatus comprising:

a supply container containing therein a supply of superfluid helium II;
an evacuable exhaust system;
a throttle element extending through said supply container and opening into said exhaust system, such that said superfluid helium II is evaporated through said throttle element into said exhaust system;
said throttle element being in the form of a valve comprising a valve sleeve and a valve element mounted for axial displacement relative to said valve sleeve;
said valve sleeve and said valve element defining therebetween in a normal control range a passage gap having a width of less than 10 .mu.m and a length which is variable by relative axial displacement between said valve sleeve and said valve element;
and
control means, connected to said valve element, for controlling the relative axial position of said valve element with respect to said valve sleeve and for thereby controlling the evaporation of said superfluid helium II through said throttle element into said exhaust system.

4 more elements

Dependencies are inferred from the claim text.

Cryogenic apparatus

Life of this patent

Cryogenic apparatus

Life of this patent

Abstract

Claims12