The interior of the coilgun, gunsling relay and slingatron consists of either a vacuum or a
helium gas at a very low pressure. If these contraptions are
surrounded by dense atmosphere, they must be enclosed in a vacuum
chamber. When the projectile leaves the chamber via an explosively
driven valve, a large volume of air leaks in before the valve is
closed. To reduce the leak, plasma is placed between the chamber
and the valve. The low density and high viscosity of the plasma
reduce the leak by 3 orders of magnitude. The plasma window lasts a
fraction of a second -- long enough to open and close the valve and
yet short enough to draw power from a large electromagnet.
Plasmatron and shaped charge detonation may prove to be less
expensive methods of making plasma than electrodes used by Ady
"High-pressure arcs as vacuum-atmosphere interface and plasma lens
for nonvacuum electron beam welding machines, electron beam
melting, and nonvacuum ion material modification," Journal of
Applied Physics, Vol. 78, No. 9, November 1 1995, pp.
Web page at
Brookhaven National Laboratory.
Discover Magazine, February 1997, p. 20 (Second half of the
paper issue is missing.)
at von Karman Institute in Belgium.
Curator: Al Globus
NASA Responsible Official: Dr. Ruth Globus
If you find any errors on this page contact Al Globus.
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