Optical isolation of spectral lines emitted by sputtered tungsten in a weakly magnetized plasma

Optical isolation of the clockwise or the counter-clockwise circular polarization of spectral lines was applied to emission of sputtered tungsten atoms. As a result one measures the weak magnetic field at plasma-surface interface resulting in splitting of spectral lines (W I at 4008.751 angstrom and 4982.593 angstrom) being negligibly small with respect to the Doppler broadening. One relies only on the phase rotation of a reflected circular polarized light propagating at the normal incidence to the mirror-like surface. The spectral shift of the signal from sputtered W atoms on the detector using high-resolution spectrometer provides the value of the magnetic field at a known dispersion, i.e. no further modeling or additional assumption on the distribution of atoms is required. The isolation of spectral line components is equivalent to isolation of the effect of the magnetic field from the measured line shape. It is complete for Zeeman triplet lines and partial for other lines. The results are found to be in a very good agreement of 3% with calculations and the Zeeman resolved laser absorption spectroscopy (10%) on metastable levels of Ar I atoms.