Radiation from a crimped V-groove in the electrically heated metallic element of a high-resolution infrared spectrometer is more intense than that from plane areas adjacent to the element. Radiation from the vee and the flat was compared by alternately focusing on the entrance slit of a spectrograph

Burkhard, D. G.

Rao, K. N.

English

NASA Technical Reports Server

I	 I I	 5"	 10.52 
LJJJ 0.051 cm
4mm 
Cross Section 
Details of the Element 
February 1971	 Brief 71-10031 
NASA TECH BRIEF 
Marshall Space Flight Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. 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. 
Improved Source of Infrared Radiation for Spectroscopy 
The problem: 
Devise an improved source of continuous, intense 
infrared radiation for high-resolution spectroscopy. 
The solution: 
Crimp a V-groove in the electrically heated metallic 
element. Radiation from such a groove was found to 
be more intense than that from plane areas adjacent 
to the element. 
How it's done: 
The experimental element was a ribbon of molyb-
denum, 7.62 cm (3 in.) long by 0.051 cm (0.020 in.) 
thick. Crimped along the length of the ribbon, adjacent 
to a 5 mm wide flat (see fig.) was a vee, 4 mm deep with 
an internal angle of 0.52 rad (30 deg). The element was 
heated by 1.5 V, 200 A ac (limited by available power). 
Element degradation was prevented by operating in 
a partial vacuum of 1.3 to 0.13 mN/rn 2
 (10 I to 10-6 
torr) in a bell jar of borosilicate glass (17 cm high, 
7.5 cm l.D.). The flange between the jar and the dif-
fusion pump immediately below the jar was part of a
precisely adjustable table that enabled focusing dif -
ferent areas of the element on the entrance slit of a 
spectrograph. During operation, a potassium bromide 
window (75 mm diam, 9 mm thick) in a water-cooled 
holder was sealed to the front of the jar. 
The sealed lid was a water-cooled copper plate con-
taining the mounting assembly of the metallic element. 
The stainless steel holders of the element were bolted 
to water-cooled copper conductors entering through 
the lid, and were machined to accommodate the vee 
and flat so as to maximize the area of contact between 
the element and the holders. One conductor was in-
sulated from the lid, the other was fitted with a 
variable-tension device to prevent the element from 
buckling as it heated and expanded. 
The radiation from the vee and from the flat was 
compared by alternately focusing them on the entrance 
slit of a spectrograph. An element in the as-supplied 
condition was used for measurements with the entire 
element in place. Other measurements were taken 
through a modified technique in which the flat and the 
vee were inserted individually and observed. In addi-
tion, some elements were heated to 1693°K (1420°C) 
prior to testing. 
Preliminary results show that the radiation from 
the vee is more intense than from the other surfaces, 
but further experimentation is required before more 
definitive conclusions can be drawn. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Code A&TS-TU 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: TSP71-10031
(continued overleaf) 
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.
https://ntrs.nasa.gov/search.jsp?R=19710000031 2020-03-17T02:17:12+00:00Z
Patent status: 
No patent action is contemplated by NASA. 
Source: D. G. Burkhard and K. N. Rao of

P.E.C. Research Associates, Inc.

under contract to

Marshall Space Flight Center 
(MFS-20613)
. 
. 
Brief 71-10031	 Category 03


Improved source of infrared radiation for spectroscopy

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server