Cyclic radiation technique has been developed for determining absorptance and emittance of metal surfaces. Using this technique both absorptance and emittance can be determined from one set of data, and variable and controlled temperature levels are possible

Jack, J. R.

English

NASA Technical Reports Server

December 1966	 Brief 66-10630 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Technique for Measuring Absorptance and Emittance 
by Using Cyclic Incident Radiation 
A new technique has been developed for determin-
ing absorptance and emittance of metal surfaces by 
the use of cyclic radiation. The proposed method is 
based on the use of a strip of metal placed in a 
vacuum environment such that no convection heat 
transfer occurs. The strip is exposed to simulated solar 
radiation and is supported at both ends. Each end is 
held to the same constant temperature by a heat sink, 
. whose temperature can be controlled to heat or cool 
the strip. With steady-state conditions established to 
yield an isothermal test area (the strip midpoint), the 
incident radiation is varied in a periodic fashion. 
This measuring technique has several desirable 
characteristics and is capable of yielding absorptance. 
a and total hemispherical emittance t over a wide 
range of temperatures. The desirable features exhib-
ited by the proposed experimental method are: 
(1) a, E, and a/E can be determined independently 
and simultaneously from one set of data. 
(2) By proper selection of cooling, sample geom- 
etry, and radiation intensity, a range of sample 
temperatures can be provided. 
(3) The measurement accuracy is promising. 
Two experiments have verified the concept. 
Notes: 
I. These investigations were conducted in the NASA-
Lewis pilot solar simulator facility at space condi-
tions (a pressure of 10- 12 torr and a background 
temperature of 4.2 1 K) on a 2-mil thick, pure 
copper sample and a 1-mil thick 304 stainless steel 
sample at temperatures of 327° K and 274° K 
respectively.
2. Metals, such as stainless steel and aluminum, are 
being investigated for temperatures ranging from 
1000 to400°K. 
Additional details are contained in NASA Techni-
cal Memorandum X-52193 "Technique for Meas-
uring Absorptance and Emittance by Using Cyclic 
Incident Radiation," by John R. Jack, Lewis Re-
search Center. 
Inquiries concerning this invention may be directed 
to:
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 23365 
Reference: B66-10630 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code GP, 
Washington, D.C. 20546.
Source: John R. Jack 
(Lewis-321) 
Category 02 
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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Technique for measuring absorptance and emittance by using cyclic incident radiation

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