“…Moreover, the transitions between the L = 0 − 3 terms, split off from the Coulomb levels, provide the greatest contribution to the UHF radiation, where L is the angular momentum of the weakly bound electron with respect to the perturbing particle of the medium [63]. A non-equilibrium two-temperature plasma is formed at 10 , where the states with principal quantum numbers n ≈ 20 ÷ 60 will be populated most effectively [63].…”