Understanding the competitive behavior of recombination processes and their effect on ionization balance and radiative loss rate

The study of ionization balance is critical to assess the plasma dynamics in a range of plasmas, such as low density (e.g., astrophysical plasma), intermediate density (e.g., magnetic fusion plasma), and high density (e.g., Z-pinch plasma). Importantly, the ionization balance is governed by different mutually competing atomic processes, such as electron-impact ionization, autoionization, electron excitation, deexcitation, recombination, etc. In the present work, we have performed a detailed study to understand the competitive behavior of recombination processes, i.e., charge-exchange, radiative recombination, three-body recombination, and electron capture, and their effect on the ionization balance. We have employed a steady-state collisional radiative model to calculate the level population densities in nitrogen-hydrogen and neon-hydrogen mixture plasmas, where the requisite rate coefficients of several atomic processes are computed using the Maxwellian distribution. The calculated level populations are then used to determine the charge-state distribution and average charge state of the plasma species. Further, we have also studied the variation of radiative loss rate with respect to temperature, and the effect of including the different recombination processes in order to ascertain their crucial role in plasma cooling. The results presented at the meeting will be accompanied with detailed explainations of the important physical phenomena.