Comparison of collisional radiative models for edge electron density reconstruction from Li I (2s-2p) emission...

Four collisional radiative models (CRMs) for reconstruction of the edge electron density profile from the measured Li I (2s-2p) emission profile of an accelerated lithium beam are compared using experimental data from DIII-D. It is shown for both L- and H-mode plasmas that edge density profiles reconstructed with the CRMs DDD2, ABSOLUT, [Sasaki et al. Rev. Sci. Instrum. 64, 1699 (1993)] and a new model developed at DIII-D agree in a density scan from n(e) (ped) = (2.0-6.5) × 10(19) m(-3) within 20%, 20%, <5%, and 40%, respectively, of the pedestal density measured with Thomson scattering. Profile shape and absolute density vary in a scan of the effective ion charge Z(eff) = 1-6 up to a factor of two but agree with Thomson data for Z(eff) = 1-2 within the error bars.