Electrostatic deflection analyzer with three spherically concentric grids allows production of electrons within a small volume at the center of the inner sphere. By applying a retarding potential between the middle and inner spheres, the energies of the electrons can be measured

Samson, J. A. R.

English

NASA Technical Reports Server

I. 
Monochromator 
r 
L
ator 
June 1970
	 Brief 70-10138 
NASA TECH BRIEF 
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 Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Electron Energy Analyzer 
Electron Multiplier 
1500 V 
Focusing Spheres
-- 1700V 
- 2000V 
/ /	 Photomultiplier 
/Coiiimaiing Cylinders 
Analyzing Region
-v
-*•--- Retarding Voltage 
IF—] 
Electron Energy Analyzer 
The problem:	 By applying a retarding potential between the middle 
To develop an electrostatic deflection analyzer of
	 and inner spheres, the energies of the electrons can 
improved sensitivity for measuring low energy electron
	
be measured. 
energy distributions. 	 How it's done: 
The solution:	 .	 The principle of operation of the analyzer is illus-
A device consisting of three spherically concentric
	 trated in the figure. Monochromatic radiation is 
grids designed to allow the production of electrons
	 channeled by a hollow metal tube which is open at 
within a small volume at the center of the inner sphere. 	 the center of the inner sphere. The gas under study 
(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 ownedrights.
https://ntrs.nasa.gov/search.jsp?R=19700000133 2020-03-17T00:28:56+00:00Z
permeates the entire apparatus, permitting the pro-
duction of photoelectrons along the length of the light 
beam. Electrons are free to escape only in the small 
gap between the hollow cylinders, traveling in straight 
lines in the field-free region of the inner sphere. On 
entering the annulus between the inner and middle 
spheres their energies are analyzed by applying a re-
tarding potential between these two spheres. A third 
outer sphere is used to prevent field penetrations from 
the electron multiplier from upsetting the energy 
resolution of the analyzer. Energetic electrons which 
are not retarded escape through the three grids and 
are focused onto the first dynode of the electron 
multiplier. A complete scan of the retarding potential 
will provide an output from the multiplier which will 
show a series of steps. Each step will represent the 
retardation of a specific energy group of the photo-, 
electrons which in turn represents an ionization po-
tential of the gas. 
This device can be used to determine ionization 
potentials of gases and to determine specific absorp-
tion processes which occur when solar radiation is 
incident on a planetary atmosphere. The transfer of 
this device for use in industry could occur in a produc-
tion line assembly where the purity of gases is moni-
tored. Energies of the photoelectrons, are unique 
to each gas, permitting specific gases to be identified.
Notes: 
1. This device is one of the few -in existence which 
can use a vacuum monochromator to produce the 
photoelectrons. 
2. Although greater sensitivity can be achieved with 
the spherical grid analyzer, there is some sacrifice 
in energy resolution. 
3. This information should be of interest to develop-
ers of instrumentation for physical electronics re-
search and to research personnel in the television 
industry. 
4. Requests for further information may be directed to: 
Technology Utilization Officer 
Headquarters 
National Aeronautics 
and Space Administration 
Washington, D.C. 20546 
Reference: TSP70-10 138 
Patent status: 
No patent action is contemplated by NASA. 
Source: Dr. James A. R. Samson of 
GCA Corporation 
under contract to 
NASA Headquarters 
(HQN- 10373)
.. 
Brief 70-10138	 Category 02


Electron energy analyzer

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