Аннотация:Hydrogen is the main chemical component of the solar plasma, and H-ionization determines basic properties of the first adiabatic exponent Г1. Its ionization significantly differs from the ionization of other chemicals. Due to the large number concentration, H-ionization causes a pronounced lowering of Г1, with a strongly asymmetric and extending across almost the entire solar convective zone. The excited states in the hydrogen atom are modeled using a partition function, which accounts for the internal degrees of freedom of the composite particle. A temperature-dependent partition function with an asymptotic cut-off tail is derived from the quantum mechanical solution for the hydrogen atom in the plasma. We present numericalsimulations of hydrogen ionization, calculated using two partition function models:Planck-Larkin (PL) and Starostin-Roerich (SR). In the SR model, the hydrogen ionization shifts to higher temperatures than in the PL model. Different models for excited states of the hydrogen atom may change Г1 by as much as 10^(−2). The Г1 profiles for pure hydrogen exhibit a “twisted rope” structure for the two models, significantly affecting the helium ionization and the position of the helium hump. This entanglement of H and He effect provides a valuable opportunity to investigate the role of excited states in the solar plasma.
