Chapter 4: Optimization of Pump Cells: Simulation and Experiments

Hyperpolarized noble gases such as ¹²⁹Xe can be produced via a two-step process denoted as spin-exchange optical pumping (SEOP). The quantum mechanical processes underlying the SEOP process have been extensively investigated over the past decades and are understood quite well. However, the efficiency of the SEOP process also critically depends on the aerodynamic and thermodynamic phenomena taking place within the pump cell used in SEOP experiments. A number of authors have, therefore, studied the influence of the various experimental parameters such as pump cell shape and design, laser power, pump cell temperature, gas partial pressures inside the pump cell etc. with the final goal to determine the optimum conditions for SEOP experiments. The present chapter summarizes the knowledge in optimum pump cell design. The SEOP process includes two basic steps, the optical pumping of Rb and the subsequent spin exchange between the Rb electron spin and the ¹²⁹Xe nuclear spin. The influence of the experimental parameters upon these two steps is discussed.