Schematic of the experimental setup. (a) Side view of the discharge in the x-z plane. The wire is in the x-direction and carries a pulsed current which produces the fields and flows indicated. (b) The same diagram in the y-z plane showing the radial expulsion of plasma from the wire. (c) A picture of the plasma with the 1 m diam cathode in the background. Loop antennas are for different experiments. (d) End view of the setup showing the current closure of the wire by a half circular loop near the bottom chamber wall. (e) Picture of the open chamber showing the wire loop.
Schematic of the pulsing circuit.
Density formation by pulsed current. (a) Wire current waveform. (b) Probe saturation current ( plasma density) vs time at different distances from the wire. The first peak is the ejected plasma front, followed by a drop in density and gradual refilling after .
Time evolution of the plasma expulsion. Contour profiles at different times after applying a rising wire current. Density depletion (green) is preceded by an enhancement (red) which propagates supersonically away from the wire.
Three dimensional plots of density profiles at different times after applying a rising wire current. A deep density depression develops around the wire at y = z = 0.
Density depression created by a pulsed current through a circular wire loop of 30 cm diameter. (a) Schematic setup. (b) Coil current and density vs time at different distances from the wire. (c) Contour plot of the radial density profile vs time. The expansion front propagates radially at a speed of . (d) Density vs radial distance from the coil at different times, showing the density depletion near the wire.
Possible wire arrangements on a supersonic vehicle. The wire has to be close to the surface in either linear (green) or circular (red) geometry. The plasma layer will be expelled radially from the wire. A conducting vehicle body needs to have an electrical break normal to the wire to avoid short-circuiting the pulsed current.
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