Energy Transport in High-Density Spin-Exchange Optical Pumping Cells

We present in situ measurements of temperatures inside multi-atmosphere spin-exchange optical pumping cells using Raman scattering from the N₂ quenching gas. Under conditions usually prevailing in spin-exchange optical pumping experiments, we find that gas temperatures can be elevated hundreds of degrees above ambient, and that convection plays a very important role in the heat transport of the system.