A comprehensive three-dimensional computational fluid dynamics (3D CFD)
modeling of flowing-gas Rb diode pumped alkali laser (DPAL) is carried
out. The cases of
H
e
/
C
H
4
and pure He buffer gases are
investigated, and the output power and optical efficiency are
calculated for various pump powers, mole fractions of methane, buffer
gas pressures, and flow velocities. The model considers the processes
of excitation of high levels of Rb, ionization, ion-electron
recombination, and heating of electrons, which affect the diffusion
coefficient of Rb ions. Two types of Rb DPAL were studied: a low-power
laboratory-scale device with pump power of several tens of watts and a
high-power multi-kilowatt laser. Efficient operation of the Rb laser
using pure He as buffer gas can be achieved only in a large-scale
laser with a pump beam cross-sectional area of several
c
m
2
. The calculated results for such a
device were compared with those reported by
Gavrielides et al. [J. Opt. Soc. Am. B
35, 2202 (2018)JOBPDE0740-322410.1364/JOSAB.35.002202],
where a simplified three-level model based on the one-dimensional gas
dynamics approach was applied.