On the use of non-hydrogenic spectral lines for low electron density and high pressure plasma diagnostics

Spectral line shapes and shifts of non-hydrogenic spectral lines of neutral atoms are considered for diagnostics of low electron density high pressure plasmas. Difficulties in application and limitations of this spectroscopic diagnostic technique are discussed in detail. The simultaneous presence of comparable Stark, Van der Waals and sometimes resonance broadening is discussed and a procedure to deduce the electron number density from the measured line width and/or shift is described. The importance and requirement of high accuracy theoretical and experimental data for plasma diagnostics are also discussed.