Desired low energy X rays are produced by modifying commercial ion tubes and combining them with standard power supplies and control circuitry. These X rays have less deviation from the solar X ray spectrum in energy and intensity

Erdman, C. A.

Kirchner, L. P.

English

NASA Technical Reports Server

June 1967	 Brief 67-10164 
NASA TECH BRIEF
- /W 
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. 
Solar X-Ray Spectrum Reproduced in Vacuum 
The problem: 
Commercially available X-ray sources that have 
been investigated show a major deviation from the 
solar X-ray spectrum both in energy and intensity. 
Operation of these sources outside a vacuum chamber 
to beam the X-rays through a suitable window results 
in absorption of the desired low energy rays and trans-
mission of the Undesired high energy rays. Addi-
tionally, these sources require extensive shielding to 
provide operator safety. 
The solution: 
Two techniques have been explored that afford 
the production of the desired low energy X-rays at a 
relatively low investment cost by modifying commer-
cially available ion tubes and combining them with 
standard power supplies and control circuitry. 
How it's done: 
In the earlier application, the cathode assembly 
consists of a VG1-A ionization tube from which the 
grid structure has been removed and whose inside is 
coated with a conducting silver film to carry the 
necessary acceleration voltage. The filament is heated 
with a Variac, whose grid lead is connected to the 
anode of a tungsten target. In this way, the feedback 
circuit of the Variac is used to stabilize emission cur-
rent to levels as low as 10 j.La. Wavelengths correspond 
to accelerating voltages of 0.12 kv to 6.0 kv while 
the power supply delivers 0 to 5.0 kv. This produces 
a shortest available wavelength of 2.38 A and a 
dominant wavelength of approximately 3.77 A due 
to the energy distribution of the X-rays produced.
In a later application, the grid of a Veeco type 
RG-758 ion gage is replaced with a tantalum target 
while the balance of the system repeats that of the 
former except for a 10-micron-thick aluminum foil 
window interposed between the gage and the detec-
tor, in this case X-ray film of known response char-
acteristics. The predominant wavelength of X-rays 
transmitted by the foil window is found to be 9 A.. 
This latter arrangement affords an advantage over 
the earlier system in that closer spacing between 
filament and target may be had. This reduces space 
charge effects and permits larger target currents that 
result in increased X-ray flux production. 
Note: 
Inquiries concerning this innovation may , be di-
rected to:
Technology Utilization Officer 
Manned Spacecraft Center 
Houston, Texas 77058 
Reference: B67-10164 
Patent status: 
No patent action is contemplated by NASA. 
Source: Leonard P. Kirchner and Carl A. Erdman 
of Illinois Institute of 
Technology Research Institute 
under contract to 
Manned Spacecraft Center. 
(MSC-228 and 1168) 
Category 02 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19670000164 2020-03-11T20:47:26+00:00Z


Solar X-ray spectrum reproduced in vacuum

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