Self-repeating pulsed plasma accelerator operates with a wide variety of gases over a large range of pressures without complex control equipment. The accelerator combines a circular channel with a tangential channel at the entrance way of a high-velocity gas

Sabol, A. P.

English

NASA Technical Reports Server

March 1965	 Brief 65-10062 
NASA TECH BRIEF 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
Pulsed Plasma Accelerator Operates Repetitively Without Complex Controls 
DC Control 
Metered Gas C====:>
High Velocity 
Tangential Accelerator 	 Upper Electrode	
Gas Enters
.1  
Arc	
Arc Extinguishes 
\\  
/	 Arc Splits Here	 _'^N . Arc Extinguishes Here
Floating Electrode
Electrode 
t:=Z
	
_.-"	
Accelerator 
The problem: Designing a pulsed plasma acceler-
ator that can operate repetitively with a wide variety 
of gases over a large range of pressures without the 
use of complex control equipment. 
The solution: A dc-powered self-repeating pulsed 
plasma accelerator that combines a circular channel 
with a tangential channel at the entrance passage of 
a high-velocity gas. The walls of the accelerator are 
electrically conductive and serve as electrodes. 
How it's done: The two electrodes formed by the 
upper section of the tangential accelerator and the 
center section of the circular accelerator are main-
tained at different potentials by the dc power supply. 
The bottom section of the tangential accelerator and
the outer circumference of the circular accelerator 
serve as a floating electrode, which acts as a conductor 
when the plasma arc splits. The magnetohydro-
dynamic force is applied to the plasma stream by the 
dc field between the electrodes and a steady magnetic 
field (perpendicular to the plane of the paper) main-
tained within the channels from a separate source (not 
shown in the schematic diagram). The inside walls of 
the accelerator electrodes are made of a suitable 
refractory metal, and the annular spaces between the 
walls can be used for the circulation of a coolant. 
In operation, the test gas is introduced into the 
system and the arc is started in a conventional man-
ner, such as by placing a jumper between the top 
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States Govern-
ment, nor NASA, nor any person acting on behalf of NASA: A. Makes 
any warranty or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not infringe privately-owned 
rights; or B. Assumes any liabilities with respect to the use of, or for 
damages resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19650000061 2020-03-11T17:18:05+00:00Z
electrode of the tangential accelerator alid the center 
electrode of the circular accelerator and then closing 
the switch. This action starts the arc which begins to 
rotate in the direction of the arrows within the circular 
accelerator. Once the arc begins to circulate, it breaks 
into two arcs, one arc traveling down the tangential 
accelerator and the other around the circular acceler-
ator. The two arcs simultaneously reach the ends of 
both accelerators where they are extinguished. This 
operation completes one cycle and places an arc in the 
position for continued automatic high frequency 
cycling of the accelerator. 
Notes: 
1. A variety of gases, including air, can be used to 
generate plasmas in this system; operating pres-
sures and mass flows of the gases are not critical. 
2. The spent plasma can be vented directly into the 
atmosphere, into an evacuated chamber, or into a 
channel designed to accelerate or decelerate the 
flow. When the accelerator operates at high pres-
sures, an exit nozzle can be used to vent the gas 
at high velocity and low temperature.
3. The operational simplicity and negligible erosion 
of the electrodes recommend this accelerator for 
experimental aerodynamic and heat-transfer 
studies in an air atmosphere and aS an arc heater. 
4. Inquiries concerning this invention may be directed 
to:
Technology Utilization Officer 
Langley Research Center 
Langley Station 
Hampton, Virginia, 23365 
Reference: B65-10062 
Patent status: NASA encourages the immediate 
commercial use of this invention. Inquiries about 
obtaining rights for its commercial use may be made 
to NASA, Code AGP, Washington, D.C., 20546. 
Source: Alexander P. Sabol 
(Langley48)
. 
:0 ^ 
Brief 65-10062	 Category No. 01


Pulsed plasma accelerator operates repetitively without complex controls

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