Density of atoms in excited states (thick solid curve, left ordinate) as a function of the principal quantum number n (lower abscissa) for a plasma density Np=105cm-3. The thin solid curve gives the production rate qn (left ordinate to be multiplied by 105) with the close dashed-dotted curve showing the initial recombinative production rate qnRec (i.e. neglecting the cascading rate qncasc). The total loss frequency is given by the sum of the level decay constant An (long-dashed curve), the collisional ionization frequency (dashed curve) and the photoionization frequency (dotted curve) where the latter corresponds to an enhanced solar radio flux as appropriate for a strong ('Type IV') solar burst (see FIG.8b) (Fsol=1). (See FIG.6 for normal solar flux conditions, The upper abscissa shows the frequency of the n-alpha transition for the quantum number n and gives an approximate idea which levels are responsible for scattering an electromagnetic wave of a certain frequency.
See FIG.8c for the resulting scattering coefficient.