An atomic and molecular hydrogen collisional-radiative model tailored forplasma detachment studies

Collisional-radiative (CR) models are widely used to study the atomic state populations and radiative properties of

plasmas, where the dynamics are governed by the competition between collisional and radiative processes. These

models are typically applied in scenarios where transport effects can be neglected or decoupled in modeling. However,

in more complex situations of large Knudsen numbers, such as those encountered in divertor plasma detachment, both

transport and CR processes significantly influence plasma behaviors, and standalone or standard CR models can not

capture this coupling and miss even some of the qualitative trends. The current work introduces a new model that

incorporates transport effects into a CR model for divertor plasmas, explicitly accounting for sheath-regulated ion flux

and two separate channels of wall recycling via surface refelection and desorption. The model’s limiting behaviors

are verified against a further reduced CR formulation, and we demonstrate that the coupling between transport and CR

processes strongly impacts the local ionization balance and hence plasma detachment.