Transient-heat transfer gage measures the total radiation intensity from vacuum ultraviolet and ionized high temperature gases. The gage includes a sensitive piezoelectric crystal that is completely isolated from any ionized flow and vacuum ultraviolet irradiation

Wood, A. D.

English

NASA Technical Reports Server

.Silver Dis 
Housing
Soldered Connection 
ttom Electrode Face 
February 1969	 Brief 69-10028 
.
	
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. 
- 
Gage Measures Total Radiation, Including Vacuum UV,

from Ionized High-Temperature Gases 
Aluminum Black Coating 	 Piezoelectric Crystal 
Electric Lead
	 Potting Compound 
A transient-heat transfer gage has been developed 
to measure the total radiation intensity from vacuum 
ultraviolet (below 1200 angstroms) and ionized high-
temperature gases. Available metal thin-film or pyro-
electric gages cannot be used for such measurements. 
The surface of the thin-film gage is shorted, and the 
surface electrodes of the pyroelectric gage are pene-
trated by vacuum ultraviolet photons, causing noise 
and depolarization of the sensor crystal. 
The new transient-heat transfer gage is of rugged 
construction and includes a sensitive piezoelectric 
crystal that is completely isolated from any ionized 
now and vacuum ultraviolet irradiation. The main 
advantage of the gage is its ability to provide total 
heat transfer data without the use of a quartz window, 
which would eliminate from measurement radiation
below 1200 angstroms. The gage has a microsecond 
response time and can be repeatedly used without 
substantial change in its calibration constant. It is 
much simpler to construct, as it incorporates a ther-
mally thick metal disc rather than molecular-thickness 
metal films which are difficult to deposit. The gage 
operates by sensing thermally induced mechanical 
stress waves which travel through the disc 500 times 
laster than thermal waves. 
As shown in the figure, the gage includes a ther-
mally thick silver disc having a radiant energy-
receiving aluminum black coating on its exterior 
surface and a strain-sensing piezoelectric crystal 
bonded to its inner surface by a soldered connec-
tion. The bottom electrode face of the crystal is sold-
ered to an electric lead. The upper electrode face of 
Ct)IiIIflUCd )scrklI 
This document was prepared under the sponsorship of the National	 Government assumes any li,bility reulting 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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the crystal is connected through the silver disc and 
the gage housing to ground. The electrodes are elec-
trically insulated and the structure is given mechani-
cal rigidity by a potting compound, which also bonds 
the gage elements together. 
Surface heating due to radiation absorbed on the 
aluminum black coating produces a thermally induced 
strain on the silver disc. This strain, a radial expan-
sion of the silver disc, is proportional to the heat flux 
and is transmitted rapidly to the piezoelectric crystal. 
The polarization vector of the crystal is normal to the 
strain direction, resulting in an electrical charge pro-
portional to the heat flux being developed between 
the crystal electrode faces. The electrical output from 
the gage is delivered to a voltage recorder or display 
device such as an oscilloscope. 
Unwanted pressure and vibration response from 
plasma can be eliminated by housing the gage in a 
cavity during measurement. Gages in such housings 
were used to measure the total radiant intensity of air 
plasma at 10 , 000 0 to l5,000°K in the reflected shock 
region of a 12-inch-diameter, arc-driven shock tube. A 
gage was supported in a cavity viewing the radia-
tion through a small windowless aperture located 
flush with the inside wall of the shock tube. The gages
performed satisfactorily until the inflow struck the 
gage surfaces and obliterated the radiative signal 
by a higher rate of convective heating. The gages 
were not harmed by this adverse environment. They 
were used for more than 60 shots without, any substan-
tial change in their calibration constants. 
Notes: 
1. Additional details are given in a disclosure avail-
able from the 
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91 103 
Reference: B69-10028 
2. The results of experimental measurements with 
the gage on the total radiant intensity from a 
plane slab of stagnant hot test gas created in 
the reflected shock region of a 12-inch-diameter, 
arc-driven shock tube are discussed in AIAA 
Paper No. 67-311, "Measurements of the Total 
Radiant Intensity of Air," by A. D. Wood, H. 
Hoshizaki, J. C. Andrews, and K. H. Wilson, April 
17-20, 1967. Copies of the paper are available from 
American Institute of Aeronautics and Astronautics. 
(Price A1AA member $0.75, nonmember $1.50.) 
Patent status: 
This invention is owned by NASA, and a patent ap-

plication has been filed. Royalty-free, non-exclusive 
licenses for its commercial use will be granted by
NASA. Inquiries concerning license rights should be
made to NASA, Code GP, Washington, D.C., 20546.
Source: A. D. Wood
of Lockheed Missiles and Space Co.
under contract to

NASA Pasadena Office
(XN P-09802)
S 
Brief 69-10028
	
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Gage measures total radiation, including vacuum UV, from ionized high-temperature gases

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