Methods for spectroscopic measurement of electric field in atmospheric pressure helium discharges

A short overview of the emission spectroscopy methods for measuring the macroscopic electric field in high pressure discharges with helium is given. The occurrence of macroscopic electric field is a consequence of the space charge buildup. It is a common feature of discharge sheaths, streamer heads and double layers. The spectroscopic methods are based on polarization-dependent Stark splitting and shifting of atomic lines in the presence of a relatively strong electric field. For high pressure discharges Stark shifting of helium lines and their forbidden counterparts is used. The advantage of Stark methods is their ab initio basis which makes them independent on other plasma parameters. A different method for field measurement, based on the helium line ratio, can be applied in cases where the Stark method cannot be used.