  The line ratios R and G of the three main lines of He-like ions (triplet:
resonance, intercombination, forbidden lines) are calculated for CV, NVI, OVII,
NeIX, MgXI, and SiXIII. These ratios can be used to derive electron density n_e
and temperature T_e of hot late-type stellar coronae and O, B stars from
high-resolution spectra obtained with Chandra (LETGS, HETGS) and XMM-Newton
(RGS). All excitation and radiative processes between the levels and the effect
of upper-level cascades from collisional electronic excitation and from
dielectronic and radiative recombination have been considered. When possible
the best experimental values for radiative transition probabilities are used.
For the higher-Z ions (i.e. NeIX, MgXI, SiXIII) possible contributions from
blended dielectronic satellite lines to each line of the triplets were included
in the calculations of the line ratios R and G for four specific spectral
resolutions: RGS, LETGS, HETGS-MEG, HETGS-HEG. The influence of an external
stellar radiation field on the coupling of the 2^3S (upper level of the
forbidden line) and 2^3P levels (upper levels of the intercombination lines) is
taken into account. This process is mainly important for the lower-Z ions (i.e.
CV, NVI, OVII) at moderate radiation temperature (T_rad).
  These improved calculations were done for plasmas in collisional ionization
equilibrium, but will be later extended to photo-ionized plasmas and to
transient ionization plasmas. The values for R and G are given in extensive
tables, for a large range of parameters, which could be used directly to
compare to the observations.
