The following is shown on the basis of a solution of the integral diffusion equations for radiation in a multilevel helium atom under low‐temperature plasma conditions (Te=5000‐10000°K) in the ‘‘vertical slab’’ model with variable electron densities: (a) Neutral helium is ionized by coronal radiation mainly in the &lgr;&lgr;100‐300A spectral region: the degree of helium ionization is maximum at the boundary planes. (b) The 23S level is destroyed by electron impacts, and the 21S level decays via the escape of the quanta of &lgr;584A through the 21P level. (c) Emission in the resonance line &lgr;584A (21P→11S) occurs due to recombination to 21S with subsequent absorption of quanta of infrared radiation &lgr;20581A. (d) The radiation of helium is generated in the vicinity of the boundary planes in the penetration of radiation with &lgr;=200A, where the density of matter decreases gradually down to the coronal value. In the subordinate lines, the radiation is conditioned by quasi‐resonance scattering of photospheric radiation. (e) The calculated absolute values of the intensities of helium and hydrogen lines are in good agreement with the observations. There was a supposition that the electron density is changed by the definite law as it is given on the Figure 2.