The absorption effect of the Lα-line Supplement to the paper 'On the Correlation Between the Hα-line emission rate and the ablation rate of a hydrogen pellet in tokamak discharges' – Nuclear Fusion 24 (1984) 697

Several assumptions made in a previous study of the correlation between the Hα-line emission rate and the ablation rate of a hydrogen pellet injected into a tokamak discharge showed that the emission layer of the ablatant as optically thin with respect to all levels of the principal quantum number, n.

While this may be justified for higher values of n, it requires some consideration about the resonance line, Lα, the Lyman alpha line. To study its possible absorption effect, the authors consider the extreme case that the Lα-line is completely absorbed