Glow plasma stabilization

Abstract

Provided are methods, apparatus and systems for stabilization of a glow discharge from a plasma. Also provided are methods, apparatus and systems for processing optical signals from a stabilised glow plasma with enhanced signal to noise recovery. A first method comprises: generating an electric field within a plasma cell using an alternating excitation voltage to excite particles within the cell, to produce a glow discharge from a plasma in the plasma cell in a resonant condition; monitoring, in each excitation cycle of the alternating excitation voltage, one or more signals that correlate with glow discharge optical emissions from the plasma in the plasma cell; and, in response to said monitoring, controlling one or more operating conditions for the plasma cell to maintain the glow discharge emissions from the plasma within a desired operating range in each excitation cycle of the alternating excitation voltage. A relatively stable glow discharge optical emission is maintained via dynamic resonant feedback control of operating conditions such as the electric field that is used to excite particles within the plasma cell. The stabilization of the glow plasma can be used in glow discharge optical emission spectroscopy (GD-OES) for gas analysis and in other applications.