Low-density laboratory spectra near the He II λ304 line

Aims. To interpret the EUV spectra of the solar corona, one hopes for laboratory data of specific chemical elements obtained under coronal conditions. Methods. EUV spectra of He, C, N, O, F, Ne, S, Ar, Fe, and Ni in a 40 angstrom wide wavelength interval near lambda 304 were excited in an electron beam ion trap. Results. We observe some two hundred lines about half of which are not yet identified and included in spectral models. Conclusions. Our data provide a check on the atomic data bases underlying the spectral models that are used to interpret solar corona data. However, a multitude of mostly weak additional lines taken together represent a flux that is comparable to that of various primary lines.