Apparatus and method for forming a high pressure plasma discharge column

Abstract

An apparatus for producing a stable, high pressure plasma column with long length, and high axial uniformity. Rotating a gas-filled tube about an horizontal axis creates a vortex with minimal, or no shear flow. Such a vortex provides a stable equilibrium for a central column of high temperature gas and plasma when, for a given rotation speed, the centrifugal force dominates over the gravitational force inside the smallest radial dimension of the containment envelope. For gas pressures sufficiently high that the particle mean free path is short compared with the thickness of the gas layer between the central plasma column and the wall, thermal transport across this sheath layer is small and its temperature is low. High pressure discharges inside a rotating envelope may be sustained by a variety of means, including electrical, electromagnetic and chemical; they may find application in plasma torches, light sources, etc. One preferred embodiment used direct current between co-rotating electrodes to sustain a one-meter-long plasma column less than 5 mm in diameter. Another preferred embodiment employed microwave heating to produce a perfectly centered plasma flame 0.5 meters long into which tens of kilowatts of power can be coupled.