Device provides stable flux output for calibration of ultraviolet spectrum

Kerr, D. E.

English

NASA Technical Reports Server

October 1975	 B75-10272 
NASA TECH BRIEF 
Lyndon B. Johison Space 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. 
Ultraviolet Hydrogen-Discharge Lamp 
.
The problem: 
Conventional hydrogen arc lamps are often used in 
the calibration of ultraviolet sensing instruments. The 
problem with these lamps, however, is that their 
outputs have large variations in intensity. Such 
instabilities prevent proper intensity calibration. 
The solution: 
A stable flux output can be obtained from a 
newly-developed hydrogen-discharge lamp. The lamp 
generates an ultraviolet spectrum ranging from 1,175 
to 1,700 A and is stable enough for accurate intensity 
calibration.
How it's done: 
The key lamp elements are uranium, uranium 
hydride, and hydrogen gas. Uranium provides two 
important features necessary for stable ultraviolet 
output: 
1. Finely-ground uranium particles serve as a power-
ful getter for all gases, except the rare ones, en-
countered in spectroscopic light sources. 
2. Uranium readily forms compounds with most 
elements that have suitable thermodynamic prop-
erties (such as hydride, oxide, nitride, and others). 
For example, uranium hydride, UH 3, can be 
formed and associated reversibly to yield equilib-
rium hydrogen pressures useful in discharge light 
source. 
36.2 cm___ 
Cylindrical 
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or Equivalent,
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Seal	 i	
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Seal 
2.54 cm
7.6 cm H 
2.	
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1.3 cm
Power 
Suool' 
Ballast
Resistor
20 Kilohms
MgF2 Window 
Torr Seal 
Vacuum 
Epoxy 
Close Tube 
Frit 
Heater 
	
rl Uranium 
Ultraviolet Hydrogen Discharge Lamp
(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=19750000272 2020-03-19T20:14:09+00:00Z
The basic lamp configuration as shown includes 
pure metal uranium mixed 50/50 with UH 3. The 
mixture is contained in a spherical bulb surrounded 
by an electrically-controlled heater circuit. This 
mixture is obtained by careful regulation of hydrogen 
pressure and temperature during fabrication. Metal 
uranium is exposed to H 2 until the proper 50/50 
proportion is obtained. 
The heater circuit surrounding the spherical bulb 
controls the temperature within ±10 C with a feedback 
circuit. The feedback includes a thermistor tempera-
ture sensor which is in direct contact with the bulb. 
Typical equilibrium temperature of the lamp is 190° C 
with a hydrogen pressure of 0.36 torr, although stable 
operation can be obtained for different values of 
pressure and current. Lamp current is generated by a 
2-kV dc power supply. The supply is accurate to 
within ±0.05 percent. The resulting ultraviolet output 
is viewed through a MgF 2 window. 
Test results indicate that the lamp operating at 60 
mA, and the bulb temperature set at 190° C, gives a 
rich spectrum of molecLiar hydrogen and a strong 
Lyman a at 1,216 A, the latter with some self-reversal. 
A spectrum search between 1,200 and 1,700 A 
indicates no traces of impurities. The lamp output is 
very stable: the intensity varies only to within 1 
percent/hour.
Notes: 
1. The lamp is described in the following report: 
Final Report for Apollo 17 Ultraviolet Spectrom-
eter Experiment (S-169) 
NASA CR-140316 (N75-10128) 
A copy of this report may be obtained at cost from: 
Technology Application Center 
University of New Mexico 
Albuquerque, New Mexico 87131 
Telephone: 505-277-3622 
Reference: B75-10272 
2. Specific technical questions may be directed to: 
Technology Utilization Officer 
Johnson Space Center 
Code AT3 
Houston, Texas 77058 
Reference: B75-10272 
Patent status: 
NASA has decided not to apply for a patent. 
Source: D. E. Kerr of
Johns Hopkins University

(MSC-14793)
. 
Categories: 03 (Physical Sciences) 
01 (Electronics - Components 
B75-10272	 and Circuitry)
	 S


Ultraviolet hydrogen-discharge lamp

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