Theoretical He I line intensities in low-density plasmas

A capture-collision-cascade model has been developed for calculating recombination spectra of He I in nebular conditions. The method of solution closely follows the treatment of Brocklehurst. The results of computations at temperatures from 312.5 to 20000 K and electron densities Ne of 102, 104 and 106 cm-3 are presented. The singlets have been treated in both case A and B conditions, the triplets in case B only. The He i results use newer data than the calculations of Brocklehurst and highlight an error in his work. These calculations can be used to interpret the line emissions from He I in the optical and infrared bands.