Metal-line cooling
= Metal-line cooling
{title2=$\Lambda(T,Z)$}
Heavy elements provide many ionic transitions at <temperatures> where <hydrogen> and <helium> have lost their most effective line emitters. <Metal-line cooling> can therefore increase the plasma cooling function substantially and broaden its <temperature> features. Low-energy fine-structure transitions also permit cooling below the <hydrogen> atomic threshold when the relevant <ions> and <electrons> are present.