Measurements of Reactive Plasma Parameters Obtained from Spectral Profiles of Particles by Laser Spectroscopy

The spectral line shapes of particles (atoms, molecules, or ions) in plasmas are determined froma radiative transition probability (natural broadening), a collision frequency (pressure broadening), an electric field (Stark broadening), a magnetic field (Zeeman splitting), and a velocity distributionfunction (Doppler broadening). In addition, the intensity ratios of spectral lines are due to thepopulation densities in electronic, vibrational, or rotational levels, which are related directly totemperature. Among these effects, Stark and Doppler broadenings and intensity ratios of spectrallines have been used for diagnostics of reactive plasmas to yield respective plasma quantities. In thispaper, the mechanisms of determining these effects are reviewed briefly, and a laser and other hardwarefor the measurements of spectral line shapes are then discussed, followed by typical examplesof the measurements in reactive plasmas, with comments for future perspective.