A temporally and spatially resolved electron density diagnostic method for the edge plasma based on Stark broadening

An electron density diagnostic (≥10¹⁰ cm⁻³) capable of high temporal (ms) and spatial (mm) resolution is currently under development at Oak Ridge National Laboratory. The diagnostic is based on measuring the Stark broadened, Doppler-free spectral line profile of the n = 6–2 hydrogen Balmer series transition. The profile is then fit to a fully quantum mechanical model including the appropriate electric and magnetic field operators. The quasi-static approach used to calculate the Doppler-free spectral line profile is outlined here and the results from the model are presented for H-δ spectra for electron densities of 10¹⁰–10¹³ cm⁻³. The profile shows complex behavior due to the interaction between the magnetic substates of the atom.