Foreign gas introduced into vapor phase above liquid region cools cryogenic baths. Equipment consists of gas tank and cover of styrofoam. Helium is considered the best choice to produce cooling, though any gas with boiling point lower than that of bath liquid may be used

Asher, I. M.

English

NASA Technical Reports Server

August 1972	 B72-10532 
NASA TECH BRIEF 
NASA Headquarters 
NASA Tech Briefs announce now technology derived from the U.S. space pro g ram. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Temperature Control of a Cryogenic Bath 
The problem: 
Samples undergoing cryogenic tests are usually cooled 
to low temperatures in cryogenic baths. Bath tempera-
tures have been commonly reduced by large and expen-
sive vacuum pumps which frequently introduce vibra-
tions that disturb the sensitive measurements. 
The solution: 
Cryogenic baths may be cooled by introducing a 
foreign gas into the vapor phase above the liquid region 
of the bath. Because of this method, the equipment has 
been simplified to a tank of gas and a cover such as 
styrofoam. 
How it's done: 
To further cool ithe cryogenic bath, a foreign (pre-
ferably inert) gas is introduced into the vapor region 
above the bath liquid. Part of this gas dissolves in the 
bath and thus lowers its boiling point. As a result, the 
temperature of the tested sample is reduced by the 
corresponding increment. 
Bath temperature may be measured directly with 
devices such as a platinum resistor. The lower temper-
ature level observed with this resistor is maintained with 
a periodic introduction of gas. Any gas with a boiling
point lower than that of the bath liquid may be used 
to produce additional cooling. Helium is considered the 
best choice, although the cheaper , nitrogen may suffice 
for temperatures above 100 K. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
NASA Headquarters 
Cpde KT 
Washington, D.C. 20546 
Reference: TSP72 . 10532 
Patent status: 
No patent action is contemplated by NASA. 
Source: I. M. Asher of
Division of Sponsored Research, 
Massachusetts Institute of Technology
under contract to
NASA Headquarters
(HQN-10788) 
Category 03 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
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Temperature control of a cryogenic bath

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