Glow plasma stabilization

A method for glow discharge optical emission spectroscopy for measuring concentration of one or more gases in a gas mixture supplied to a plasma cell, including stabilization of a glow discharge from a plasma generated within the plasma cell, the method comprising:

• supplying a gas mixture to the plasma cell as a gas flow;
• generating an electric field within the plasma cell using an alternating excitation voltage to excite gas particles within the plasma cell, to produce a glow discharge from a plasma in the plasma cell;
• monitoring, in each excitation cycle of the alternating excitation voltage, one or more electrical signals that correlate with glow discharge optical emissions from the plasma in the plasma cell, wherein the one or more electrical signals comprise a plasma excitation current or an electrical current in a feedback circuit;
• in response to said monitoring of the one or more electrical signals, controlling one or more operating conditions for the plasma cell in a resonant condition to maintain the glow discharge emissions from the plasma within a desired operating range in each excitation cycle of the alternating excitation voltage, thereby to stabilize glow discharge emissions from the plasma;
• and
• analyzing glow discharge emissions from the plasma in the plasma cell or analyzing the one or more electrical signals that correlate with the glow discharge optical emissions to determine the constituents of the gas mixture supplied to the plasma cell.

A system for stabilization of a glow discharge from a plasma that is generated within a plasma cell, the system comprising:

• a plasma cell for receiving a gas mixture as a gas flow to the plasma cell;
• an electric field generator for generating an electric field within the plasma cell using an alternating excitation voltage to excite gas particles within the plasma cell, to produce a glow discharge from a plasma in the plasma cell;
• and
• a controller module for:
• monitoring, in each excitation cycle of the alternating excitation voltage, one or more electrical signals that correlate with glow discharge optical emissions from the plasma in the plasma cell, wherein the one or more electrical signals comprise a plasma excitation current or an electrical current in a feedback circuit;
• and,
• in response to said monitoring, controlling one or more operating conditions for the plasma cell in a resonant condition to maintain the glow discharge emissions from the plasma within a desired operating range in each excitation cycle of the alternating excitation voltage, thereby stabilizing the glow discharge emissions from the plasma;
• and
• using the stabilized glow discharge emissions from the plasma in the plasma cell, or using one or more electrical signals that correlate with the stabilized glow discharge optical emissions, to measure the concentration of one or more gases in the gas mixture supplied to the plasma cell.