Closed Cycle 1 K Refrigeration System

Abstract

A closed-cycle refrigerator provides cooling to extremely low temperatures, particularly in the range of 0.5 K to 2.0 K. A 4 K pulse-tube cryocooler cold head or G-M cryocooler cold head liquefies helium in a first cooling chamber at a pressure at approximately 1 atmosphere. Liquid helium flows from the first cooling chamber, through a Joule-Thomson valve, and into a second cooling chamber under a pressure differential created by a pump. Helium vapor extracted from the second cooling chamber by the pump is routed back to the first cooling chamber to be re-condensed. This closed-cycle design provides continuous cooling below 2 K. Cryocooler cold head cold sections have no physical contact with subsequent cooling elements, such as the first and second cooling chambers to reduce vibration transfer. In some embodiments the cryocooler cold head is connected to a vacuum chamber via a vibration damping coupler to further reduce vibration transfer.

Description

REFERENCE TO RELATED APPLICATIONS[0001]This application claims one or more inventions which were disclosed in Provisional Application No. 61 / 756211, filed Jan. 24, 2013, entitled “CLOSED CYCLE 1 K REFRIGERATION SYSTEM”. The benefit under 35 USC §119(e) of the United States provisional application is hereby claimed, and the aforementioned application is hereby incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The invention pertains to the field of cryorefrigeration. More particularly, the invention pertains to closed cycle cryorefrigerators for temperatures below about 4.2 Kelvin.[0004]2. Description of Related Art[0005]Liquid helium has a boiling point at 1 atm (atmosphere of pressure) of 4.2 K, and is by-product of natural gas production. Helium is found in two isotopes, helium-3 (3He) and helium-4 (4He). Helium-4 is by far the most abundant isotope, and constitutes over 99.9% of the helium on Earth. As such, liquid helium makes an ide...

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Benefits of technology

[0018]The closed-cycle refrigerator also has an extra low vibration design. Cryocooler cold head cold sections of the closed-cycle refrigerator have no physical contact with subsequent cooling elements of the closed-cycle refrigerator, such as the first and second cooling chambers. In some embodiments the entire cryocooler cold head is connected to a vacuum chamber via a vibration

Problems solved by technology

Unfortunately, sources of natural gas that also contain helium are limited, and atmospheric helium migrates into space and is lost.

As helium is a limited resource, and world-wide demand has increased dramatically over several decades, the cost of this irreplaceable natural resource has also increased dramatically.

Therefore it is clear that a shortage, or worse depletion, of world helium reserves could potentially have a dramatic negative effect on the production and use of critical technologies such as magnetic resonance imaging, fiber optics and semi-conductor manufacturing, space exploration, and military rockets, for examp

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