Space resolved measurements of titanium soft X-ray emissions from FTU tokamak plasmas

X-ray spectra due to intrinsic titanium are obtained on the FTU tokamak using a crystal spectrometer with spatial resolution. He-like ion spectra are observed for ohmic and lower hybrid (LH) heated high density plasmas. In a single discharge four spectra are recorded with different lines of sight. With a post-process subroutine of an impurity transport code, synthetic spectra are built up and compared with the experimental ones. Line intensity ratios with respect to the resonance w line are studied. For the inter-combination lines x and y the agreement between experiment and simulation is satisfactory, whereas for the forbidden line z the simulations give line ratios higher than the experimental values by 25 to 40%. The electron temperatures Te deduced from the ''dielectronic'' satellite line ratios agree with the corresponding values from standard Te diagnostics. For the ''collisional'' satellite q the line intensity ratios are sensitive to the titanium ion charge distribution in the plasma core and, consequently, to the impurity transport parameters. Diffusion coefficients D equal to 0.7 and to 2.0 m2/s are obtained in the plasma core of, respectively, ohmic and LH heated plasmas. The impurity confinement time τp is deduced from the diffusion coefficient D and compared with the predictions of a τp scaling law. (orig.)