We present results for the electron-impact excitation of highly-charged sulphur ions (S8+ - S11+) obtained using the intermediate-coupling frame transformation R-matrix approach. A detailed comparison of the target structure has been made for the fou
r ions to assess the uncertainty on collision strengths from the target structure. Effective collision strengths (Upsilon s) are presented at temperatures ranging from 2times10^2(z+1)^2 K to 2times10^6(z+1)^2 K (where z is the residual charge of ions. Detailed comparisons for the Upsilon are made with the results of previous calculations for these ions, which will pose insight on the uncertainty in their usage by astrophysical and fusion modelling codes.
Rich soft X-ray emission lines of highly charged silicon ions (Si VI--Si XII) were observed by irradiating an ultra-intense laser pulse with width of 200 fs and energy of $sim$90 mJ on the solid silicon target. The high resolution spectra of highly c
harged silicon ions with full-width at half maximum (FWHM) of $sim$0.3--0.4AA is analyzed in wavelength range of 40--90 AA . The wavelengths of 53 prominent lines are determined with statistical uncertainties being up to 0.005 AA . Collisional-radiative models were constructed for Si VI -- Si XII ions, which satisfactorily reproduces the experimental spectra, and helps the line identification. Calculations at different electron densities reveal that the spectra of dense plasmas are more complicate than the spectra of thin plasmas. A comparison with the Kelly database reveals a good agreement for most peak intensities, and differences for a few emission lines.
