  A new model is presented for spin-exchange optical pumping using an
open-source code, ElmerFEM-CSC. The model builds on previous models by adding
the effects of alkali-vapor heterogeneity in optical pumping cells and by
modeling the effects of hyperpolarized-gas wall-relaxation using a diffusion
model. The code supports full, three-dimensional solutions to optical-pumping
models, and solves for (1) laser absorption, (2) alkali vapor concentration,
(3) fluid flow parameters, (4) thermal affects due to the pumping laser, and
(5) noble gas polarization. The source code for the model is available for
researchers to utilize and modify.
