AbstractThe spectroscopic diagnostics has been carried out as an example for an argon plasma from Maecker‐Shumaker type electric arc supplied by periodic variable current. It is shown that the time‐dependent runs of intensity of the plasma light may be determined using an ordinary oscilloscope. We have stated that the electron concentrationNein the plasma is the most sensitive quantity to the current pulsations. In the percentage,Nevariations at the arc axis are approximately the same as the current o