[en] Calculations of mean ratio of ionisation and radiation losses of high-temperature iron plasma of high optical density under the conditions of thermodynamic equilibrium absence at electron temperature of 10-10³ eV, plasma density N=10¹⁶-10²² sm sup(-3) and optical density NR=10¹³-10²² sm sup(-2) where R is plasma dimension is carried out. Boundaries of plasma parameters regions, where the model use of optically transperant or thermodynamical equillibrium plasma is possible; account of dielectric recombination, photoradiation by eigene radiation, cascade ionization stark widening of lines, radiation at transitions without the change of main quantum number, is necessary