On Kβ radiation of Ar16+ ions in coronal plasma

Abstract

The measured and calculated data obtained in this and earlier works for the intensity ratio G3= I[Kβ2]/I[Kβ1] of the intercombination and resonance Kβ lines corresponding to the 1s3p3P1→1s21S0 (Kβ2) and 1s3p1P1→1s21S0 (Kβ1) transitions in the coronal plasma spectrum of Ar16+ ions were compared with each other. In this work, the G3 ratio was measured on the TEXTOR (Julich, Germany) tokamak equipped with high-resolution Bragg spectrometers and other diagnostic instruments. The calculations carried out within the framework of the radiative-collision model using the ATOM, MZ, and GKU programs developed in the Lebedev Physical Institute, Russian Academy of Sciences, are in agreement, to the experimental accuracy, with all the data obtained on the PLT (Princeton, USA), ALCATOR-C (Cambridge, USA), and TEXTOR tokamaks. It is shown that the previously observed factor of 1.3–2 discrepancies between the measured and G3 values calculated using the HULLAC code and appreciably exceeding the experimental error are caused by the use of inaccurate atomic data and simplified atomic kinetics in those works. The results presented in this work are evidence for the high accuracy of our atomic data (transition rates) and for the possibility of effectively using, on their basis, the Kβ lines of multicharged ions in X-ray spectrum diagnostics of electron temperature and density in laboratory and astrophysical coronal plasma sources.