  Quantitative evaluation of tunable diode laser induced fluorescence (TDLIF)
measurements in magnetized plasma take into account Zeeman splitting of
energetic levels and intra-multiplet mixing defining the density distribution
(alignment) of excited $\mathrm{2p_8}$ multiplet is discussed in this paper.
TDLIF measurements were used to evaluate light-transport properties in a
strongly magnetized optically thick argon plasma under different pressure
conditions. Therefore, a coupled system of rate balance equations were
constructed to describe laser pumping of individual magnetic sub-levels of
$\mathrm{2p_8}$ state through frequency separated sub-transitions originating
from $\mathrm{1s_4}$ magnetic sub-levels.
  The density distribution of $\mathrm{2p_8}$ multiplet was described by
balancing laser pumping with losses including radiative decay, transfer of
excitation between the neighboring multiplets driven by neutral collisions and
quenching due to electron and neutral collisions. Resulting $\mathrm{2p_8}$
magnetic sub-level densities were then used to model polarization dependent
fluorescence, consider self-absorption, which could be directly compared with
measured polarization resolved TDLIF measurements. This enables to obtain
unique solutions for the $\mathrm{1s_4}$ and $\mathrm{1s_5}$ magnetic sub-level
densities which were in good agreement with the densities obtained by laser
absorption measurements. It is shown that LIF measurements in magnetized plasma
conditions have strong pressure dependence that should be corrected consider
effective disalignment rate. The presented measurement method and model can
help further understanding and improve description of optical emission of argon
in magnetized conditions.
