On the interpretation of the intense emission of tungsten ions at about 5 nm

• Published in: Journal of physics. B, Atomic, molecular, and optical physics Atomic, molecular, and optical physics, 2007-06, Vol.40 (11), p.2179-2188
• Main Authors: Jonauskas, V, Kučas, S, Karazija, R
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Atomic properties and interactions with photons; Atomic spectra; Exact sciences and technology; Magnetic confinement and equilibrium; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; Plasma properties; Tokamaks; X-ray spectra
• ISSN: 0953-4075; 1361-6455
• DOI: 10.1088/0953-4075/40/11/018

The origin of the intense emission band at about 5 nm, dominating the emission spectra of tungsten ions in the ASDEX Upgrade tokamak and EBIT, is discussed. It is shown that the emission spectra of various ions calculated taking into account only the excitations from the ground level agree fairly well with the results obtained in the collisional-radiative model; thus, the contribution of the excitations from the other levels is small. Though the excitation spectrum for all sequence of ions W29+-W37+ corresponds to the same transitions 4p64dN- > 4p54dN+1+ 4p64dN-1 4f, its energetic width essentially changes going on from the charge of ion q = 34 to q = 35. It is caused by the appearance of the excitations 4p1/2-4d3/2 to the open 4dN3/2 subshell, which are not quenched by configuration mixing. The satellite line at about 4.5 nm is explained by the transitions of the same type, although between configurations with one spectator 5s electron. The existence of one more group of intense lines in the region of 2 nm, corresponding to 5s-4p transitions, is predicted.