X-ray line intensities for ions of the helium isoelectronic sequence in high-temperature plasmas

Measurements are reported for the He-like x-ray spectra of argon obtained in a deuterium tokamak plasma with $N_e=(1-2)\mathrm{}\times {10}^{14}$ ${\mathrm{cm}}^{-3\mathrm{}}$ and $T_e=1-2\mathrm{}$ keV. The results are interpreted with the help of computed excitation rates and other available atomic data. The plasma sensitivity of line-intensity ratios is discussed as well as the $Z$ dependence based on earlier observations of He-like S and Cl.