Confinement of a Z-pinch plasma with cold gas end plugs

Plasma escaping from the ends of a Z-pinch can be slowed by a plug of cold gas. Model calculations predict that increasing the plug density will reduce the plasma motion, although experiments show that this effect is gained at the cost of greater heat loss. The helium plasma used in this work has a temperature of 35000K and a density of 8X10²² m⁻³. The measured heat flux into a helium end plug at 300K and 525 pascals is 130 MW.rn⁻². Outward motion of the plasma adds a mechanical flux of 830 MW.rn⁻². Increasing the plug density by a factor of four reduces the mechanical flux to 200 MW.rn⁻², but increases the heat flux to 420 MW.rn⁻². The corresponding heat loss to a solid electrode is approximately 400 MW.rn⁻². In terms of the total energy lost, the "wall of gas" is nearly as effective as a solid barrier. Linear systems at higher temperatures could avoid the impurities contributed by plasma/solid interaction by replacing the solid with a cold gas end plug.Science, Faculty ofPhysics and Astronomy, Department ofGraduat