Electron beam energy is absorbed by deflectors which allow beam distribution over an absorber located between the deflectors and workpiece. The undeflected beam passes through a hole in the absorber when the deflection is de-energized, when energized, the beam is kept to a minimum power level by deflection rate change

Downing, R. D.

English

NASA Technical Reports Server

December 1967	 Brief 67-10650 
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. 
Electron Beam Standby Absorber System 
I Electron 
Beam 
I	 I	 Sweep 
Coil 
S port 
up Structure	 N 
Copper 
Surface
Sweep
In, 
Absorber	
I 
Beam Focal Cooling Water	 Point	
'	
orkpiece 
r\ 
The problem: 
While using a swept and scanned beam raster to 
locate position or measure characteristics of that 
beam, it is necessary to absorb the energy of the 
beam in places other than a workpiece which one 
intends to weld or otherwise process. It is desirable 
that this energy be absorbed by some means requiring 
no physical motion of either the absorber or the 
intended workpiece. 
The solution: 
Deflectors cause the electron beam to be distributed 
over an absorber located between the deflectors and 
the workpiece. A hole in the absorber permits the
undeflected beam to pass through the absorber when 
the deflection is deenergized. The beam passing 
through this hole, when the deflection is energized, is 
kept to a minimum power level by deflection rate 
change. 
How it's done: 
A water cooled standby absorber is interposed 
permanently between the deflection components and 
the beam work.piece. The energy of the beam is dis-
sipated in the absorber. Along the electron beam 
axis, the time averaged energy density is much lower 
than at its focal point. This permits the absorption of 
the full beam power without harm to the absorber 
surface.	 (continued overleaf) 
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=19670000649 2020-03-11T21:40:07+00:00Z
The deflections of the beam at high speed and the 
distributive nature of the beam raster also aid greatly 
in making it possible to safely dissipate the beam 
power in the absorber. 
The beam is kept in raster on this absorber during 
adjustments of the beam parameters. When one wishes 
to use the beam, the deflection is switched off, causing 
the beam to move to its undeflected position, passing 
through the hole in the absorber, to the workpiece. 
Switching off the beam is done by reversing this 
process. 
Notes: 
I. This system permits adjustment of electron beam 
systems during full power operating conditions. 
2. Other configurations of this system are evident, 
such as off axis absorbers situated on one side of 
the beam.
3. A related system is described in NASA Tech Brief 
67-10649. Inquiries may also be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B67-10650 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: R. D. Downing
of General Electric Company

under contract to

Marshall Space Flight Center

(M FS- 14108)
. 
Brief 67-10650	 Category 01


Electron beam standby absorber system

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