Fast acting gas valve is used for injecting a short pulse of gas into a vacuum chamber during plasma acceleration experiments. It contains a lightweight closure disk that is forced away from the valve seat when an electromagnetic coil is momentarily energized and immediately rebounds from a stop back onto the seat

Hoh, F. C.

Lowder, R. S.

English

NASA Technical Reports Server

August 1966	 B66-10381 
S	
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Gas-Injection Valve Operates at High Speed 
Plastic Coil Housing 
To Capacitor & Ignitron $
	
k/Coil
Brass Valve Housing 
Vacuum 
Aluminum Stop 
Aluminum Closure Disk
	 Soft 0-Ring Valve Seat 
Plastic Insulator
Epoxy Resin 
The problem: 
Many plasma acceleration experiments require the 
injection of a short pulse of gas into a vacuum cham-
ber. For this purpose, there is a need for a valve that 
can be opened during a brief and controllable period, 
usually of the order of 100 microseconds. 
The solution: 
A new type of fast acting gas valve incorporating 
a lightweight closure disk that is forced away from 
the valve seat when an electromagnetic coil is mo-
mentarily energized; the disk immediately rebounds 
from a stop back onto the seat. 
How it's done: 
The closure disk, made of aluminum, is held on the 
0-ring.valve seat by a gas pressure of 1 atmosphere or
more. The 0-ring, consisting of a soft silicone elas-
tomer, is adhesively attached to the plastic coil hous-
ing. The coil, consisting of 4 turns of 0.7 mm X 4 mm 
ribbon, is potted in epoxy resin for electrical insula-
tion and mechanical positioning. Insulated coil leads 
from the valve chamber are connected across an igni-
tron switch and a 8.5 microfarad capacitor, which is 
normally charged to 7.0 kilovolts. The current through 
this circuit rings with a frequency of 55 kc and is 
damped out in 90 microseconds. The valve is normally 
positioned sidewise, and the disk is prevented from 
creeping away from the seat by a short cylinder that 
protrudes from the aluminum stop into a recess in the 
disk. An adjustable gap between the stop and the disk 
is normally set at 0.3 mm.
(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=19660000380 2020-03-11T17:36:02+00:00Z
Upon discharge of the capacitor through the coil, 
the disk is electromagnetically accelerated toward the 
stop, opening the valve for about 100 microseconds 
and admitting a burst of gas into the vacuum cham-
ber. On striking the stop, the disk rebounds onto the 
0-ring, keeping the valve closed until the ring be-
comes decompressed (a period of 300 to 400 micro-
seconds). This closure period is long enough for most 
plasma measurements, before the valve reopens for a 
briefer period as a result of decompression of the 
0-ring. 
Notes: 
1. The advantage of the valve consists of its short 
opening time and good reproducibility. However, 
subsequent openings of the valve due to compres-
sion and decompression of the 0-ring will limit the 
measurement time to approximately 400 microsec-
onds. It should be possible to modify the basic 
design of the valve to prevent undesirable openings.
2. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Headquarters 
National Aeronautics and Space Admin-
istration 
Washington, D. C. 20546 
Reference: B66-10381 
Patent status: 
No patent action is contemplated by NASA. 
Source: R. S. Lowder and F. C. Hoh 
of Advanced Kinetics, Inc. 
under contract to 
NASA Headquarters 
(HQ-49) 
Brief 66-10381	 Category 05


Gas-injection valve operates at high speed

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