The gas to be analyzed (Helium or Argon) is passed through a detection chamber and is submitted to an intense electromagnetic field created between two electrodes by a high frequency generator.
Under these conditions, it becomes the center of a luminous phenomenon, the characteristics of which are modified by any foreign elements in the initial gas passing through the chamber. An interfering filter is used to isolate the spectral ray from Nitrogen.
The filtered luminous intensity is then converted into an electrical current using a photoelectrical cell and amplified by an electrometer.
The tension created is proportional to the level of concentration of Nitrogen in (Argon or Helium).