Experimental and simulated argon spectra in the 2.3-3.4 nm region from tokamak plasmas

Experimental argon spectra in the 2.3-3.4 nm region from the Jet tokamak on a single null divertor configuration have been simulated. The spectra incl ude lines from five ionization states, namely from Ar15+ Li-like to Ar11+ N -like ions, Collisional-radiative models have been constructed for these fi ve Ar ions, considering electron collisional excitation and radiative decay as the populating processes of the excited states. These models give photo n emission coefficients for the emitted lines at electron density and tempe rature values corresponding to the experimental situations. Impurity modell ing is performed using a one-dimensional (1D) impurity transport code, calc ulating the steady-state radial distribution of the Ar ions. The Ar line br ightnesses are evaluated in a post-processing subroutine and simulated spec tra are obtained. The parts of the spectra corresponding to a single-ioniza tion state do not depend on the experimental conditions and show good agree ment except for the amplitude of the simulated 2s-3p Ar xvi line and the sh ape of the simulated 2.50 nm feature (composed of Ar xvi and Ar xv lines). On the other hand, the superposition of these spectra depends on the experi mental conditions, as a consequence of the fact that the ion charge distrib ution depends not only on the radial profiles of the electron density and t emperature, but also of the impurity transport coefficients, Simulations of the Ar spectra (including transport) give confidence in the atomic physics calculations; moreover, they allow the determination of the transport coef ficients in the plasma region emitting the considered ionization states, i, e. at the interior of the last closed magnetic surface (LCMS). For a correc t simulation of the amplitudes of the spectral features it is necessary to include a transport barrier inside the LCMS. As far as the atomic physics i s concerned, we report improved wavelengths for Arxv transitions and we ben chmark photon emission coefficients for XUV transitions in highly ionized a rgon.