On the theory of recombination of ultracold plasma

Results are given of the solution of an algebroid set of kinetic differential equations of populations of states of excited atoms in recombining plasma. Homogeneous nonequilibrium two-temperature hydrogen plasma with initial electron temperatures $T_{e0} = 1, 6$, 13.33 K and initial density $n_{e0} = (1\text{--}2.7) \times 10^9$ cm$^{-3}$ is considered. Comparison is made with theoretical and experimental data. The question is considered of the validity of the formulas for the probabilities of quenching an excited atom by electron impact in ultracold plasma ($T_{e0}< 100$ K). The calculation is performed for weakly nonideal ($\gamma_{e0}< 1$) and nonideal ($\gamma_{e0} \ge 1$) plasma. Dependences are obtained of the concentration of excited atoms and free electrons, the temperature of free electrons, and the nonideality parameter on the time and on the distribution of excited atoms with respect to the main quantum number.