unit of the spectrum

[SethVerlo]

As an example I am trying to use Chianti to calculate the H-alpha line, seems it only need two parameters, temperature and eDensity.
And the spectrum intensity has a unit of "erg cm−2 s−1 sr−1 A-1", I believe it is common used in the astronomy. I am confused about it as the radiation power should be related to the distance, what's the default setting of the "radiation source distance" of Chianti's calculation ? If I want to estimate the laboratory plasmas the intensity should be different.

[kdere]

Hi,
the units already include the distance information. You can use the cm^-2 as the area of your detector or the area of the source. Similarly, the sr^-1 is the steradians of the source or your detector.