Intensity vs. electron density of the ultraviolet M1 transition in Xe³²⁺, Gd⁴²⁺, W⁵²⁺, Bi⁶¹⁺, and U⁷⁰⁺ (Ti-like ions)

This work presents theoretical calculations of the intensity of the UV lines arising from forbidden M1 transitions within the ground configuration of highly ionized Ti-like ions. The intensity of these lines is calculated for different electron densities in the range 10¹¹-10¹⁶ cm^-3 and compared to lines arising from electric dipole allowed transitions between excited levels with J = 1 and the ground level (J = 0). The calculations show that the forbidden M1 transitions have a non-negligible intensity in densities that are of interest to tokamak machines. In particular, the intensity of the near UV line arising from the M1 transition between the lowest J = 3 and J = 2 levels in the ground configuration, is found to be of the order of 1% of the strongest line emitted by the ion.