Incorporate dielectronic ions into two-photon continuum

[jwreep]

Once dielectronic ions are implemented (#269), they need to be added to the two-photon continuum. This may just be a matter of validating that it works correctly.

[wtbarnes]

I agree that this needs to be worked on, but I'm not quite sure how to go about it. Maybe this is because I don't fully understand how it is done in the IDL code.

In v9 and above, dielectronic recombination is included in the level populations calculation through a two-ion model approach. See #254 for more details. However, prior to v9, these so-called satellite lines were treated separately by including a separate ion with a "_d" suffix in the database. This is still true for some ions even in version 9 and above.

What I'm not sure about is how these "_d" data are actually used. In fiasco, if there is a "dielectronic version" of the data, it can be accessed as _dielectronic_<dataset_name>, e.g. fe_15._dielectronic_elvlc would give you the data from the file fe/fe_15d/fe_15d.elvlc. Is it just a matter of making additional Ion objects for these "dielectronic versions" of each ion if they exist?