Broadening of the neutral helium 492 nm line in a corona discharge: code comparisons and data fitting
Résumé
Passive plasma spectroscopy is a well-established non-intrusive diagnostic technique.
Depending on the emitter and its environment which determine the dominant interactions and effects
governing emission line shapes, passive spectroscopy allows the determination of electron densities,
emitter and perturber temperatures, as well as other quantities like relative abundances. However,
using spectroscopy requires appropriate line shape codes retaining all the physical effects governing
the emission line profiles. This is required for line shape code developers to continuously correct
or improve them to increase their accuracy when applied for diagnostics. This is exactly the aim
expected from code–code and code–data comparisons. In this context, the He I 492 nm line emitted in
a helium corona discharge at room temperature represents an ideal case since its profile results from
several broadening mechanisms: Stark, Doppler, resonance, and van der Waals. The importance of
each broadening mechanism depends on the plasma parameters. Here the profiles of the He I 492 nm
in a helium plasma computed by various codes are compared for a selected set of plasma parameters.
In addition, preliminary results related to plasma parameter determination using an experimental
spectrum from a helium corona discharge at atmospheric pressure, are presented.
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