Profiles of nine lines of singly ionized nitrogen have been measured in a dense ($N_e=1.9\mathrm{}\times {10}^{17}$ ${\mathrm{cm}}^{-3\mathrm{}}$) high-temperature (22 800 °K) plasma produced behind the reflected shock wave in a $T$ tube. Measurements were carried out that verified the fact that the plasma was homogeneous in both the radial and the axial directions and that the plasma was optically thin at the various wavelengths where the profiles were measured. The half-widths of the measured profiles show large discrepancies with earlier reported measurements of Day and Griem and, in most cases, show significant disagreement with the theoretical predictions.

• Received 28 July 1969

DOI:https://doi.org/10.1103/PhysRevA.1.221