Dielectronic satellite spectra of hydrogenlike titanium (Ti xxii)

High-resolution spectra of the Ly-${\alpha }_1$ and Ly-${\alpha }_2$ lines of hydrogenlike titanium, Ti XXII, and the associated dielectronic satellites which are due to transitions $1snl-2pnl$ with $n\ge 2$, have been observed from tokamak discharges with auxiliary ion-cyclotron heating with central electron temperatures of 2 keV and central electron densities of 8× ${10}^{13}$ ${\mathrm{cm}}^{-3\mathrm{}}$ on the Princeton Large Torus (PLT). The data have been used for a detailed comparison with theoretical predictions based on the $Z$-expansion method and on the multiconfiguration Thomas-Fermi—potential wave-function method (SUPERSTRUCTURE code). The predictions from the $Z$-expansion method are in excellent agreement with the observed spectral data except for minor discrepancies between the theoretical and experimental wavelengths of 0.0003 Å for the $n=2\mathrm{}$ satellites and of 0.0001 Å for the separation of the Ly-${\alpha }_1$ and Ly-${\alpha }_2$ lines. The latter discrepancy is, however, removed if the Lamb shift and relativistic effects of order ${\alpha }^4$ are taken into account. Very good agreement with the experimental wavelengths is also obtained for the results from SUPERSTRUCTURE though somewhat larger and systematic discrepancies (≃0.0009 Å) exist. The observed spectra have been used for diagnosis of the central ion and electron temperatures of the PLT discharges and for a measurement of the total dielectronic recombination rate coefficient of Ti XXII. The measured rate coefficient is in good agreement with the predictions from both the detailed calculations and Burgess's general formula.