Spectra of O II in the plasma boundary of TEXTOR-94

D. Borodin, I. L. Beigman, L. A. Vainshtein, A. Pospieszczyk, S. Brezinsek, A. Huber

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Spectra of the O II ion were obtained with temporal and spatial (along the poloidal radius) resolution by injecting of oxygen-containing molecules through a block of the upper poloidal limiter of TEXTOR-94 into the boundary plasma. Three different wavelength regions (46604±100, 43404±100, 37305±100 Å) were observed during reproducible TEXTOR-94 discharges with ne = 1 × 1018 m-3, Te = 90 eV at the last closed flux surface (LCFS). For calibration purposes the oxygen emission was simultaneously registered in all discharges with a 2D camera using the light from an O II line at 4416 Å. Radial intensity distributions of lines corresponding to the transitions 2p2[3P]3s-2p2[3P]3p (components of the multiplets 4P-4S, 4P-4P, 4P-4D, 2P-2D and 2p2[1D]3s-2p2[1D]3p (doublet. 2D-2D) were measured. It is shown that the relative intensities of the lines inside the multiplets are in good agreement with theoretical data calculated in SL-coupling. An appropriate collisional-radiative model (the level list and the corresponding atomic database) has been developed and calculations have been carried out using the GKU kinetic code developed at the P.N. Lebedev Institute. Cross-sections of atomic processes have been calculated using the ATOM code by the K-matrix method. A comparison of theoretical and experimental data is presented. It is shown that the relative multiplet intensities have a weak dependence on electron density and temperature. The populations of the ground configuration states of O II were investigated. Absolute values for the 'ionization per photon' were measured and a comparison with modelled values is given.

Original languageEnglish
Pages (from-to)2251-2269
Number of pages19
JournalPlasma Physics and Controlled Fusion
Issue number10
StatePublished - Oct 2002
Externally publishedYes


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