Radiative lifetimes of excited W II levels

Radiative decay rates for W I, W II and W III allowed and forbidden transitions of interest for spectroscopic diagnostics in fusion plasmas

“…The lifetimes by Schnabel et al (1998) agree, within the quoted uncertainties, with the results of Kwiatkowski et al (1984) for two levels, the measurement reported by these authors for 42 390.27 cm −1 being obviously in error a Observed air wavelengths taken from Kramida and Shirai (2006).…”

“…by more than one order of magnitude. A discrepancy of 40% between the laser measurement of Schnabel et al (1998) and the beam-foil measurement of Henderson et al (1999) is observed for the level at 54 229.06 cm −1 , but according to the quoted uncertainties (10 and 3%, respectively) and the limitations inherent to the techniques involved, the first result is expected to be the most accurate. This is confirmed, in an indirect way, by the nearly perfect agreement observed, for two levels, between the results of Schulz-Johanning et al (1999) and of Kwiatkowski et al (1984) and, in a more direct way, by the relativistic Hartree-Fock calculations including corepolarization effects (HFR+CPOL) due to Nilsson et al (2008).…”

“…Kwiatkowski et al (1984) measured three lifetimes using the TR-LIF method, the ions being produced by the sputtering technique in a low-pressure discharge. Using the TR-LIF technique, radiative lifetime measurements were also carried out by Schnabel et al (1998) for 19 selected levels with energies between 36 000 and 55 000 cm −1 and by Schulz-Johanning et al (1999) who used a linear Paul trap for investigating two W II lifetimes. More recently, Henderson et al (1999) reported three lifetime values using the beam-foil method.…”

2D display of tungsten impurity in a free-burning arc using laser-induced fluorescence

“…For a successful application of LIF as a diagnostic tool for plasma impurities, the relevant atomic data have to be known. For W I and W II, we obtained these data from [20][21][22][23][24][25][26][27], whereby we preferred newer publications and experimental data against older and theoretically calculated values. The atomic data used for LIF in this work are given in table 1.…”

Lifetime measurements and calculated transition probabilities in W III

“…Although several lifetime measurements [7][8][9][10][11][12][13][14] or experimental transition probability determinations [15][16][17][18][19] have been reported in neutral (W I) as well as in singly ionized tungsten (W II), radiative data on doubly ionized tungsten are still extremely sparse. The only work available is that of Schultz-Johanning et al [20], who measured lifetimes for three levels with the time-resolved laser-induced fluorescence (TR-LIF) technique and branching fractions (BF) with the Fourier transform technique for 81 transitions in the 154-334 nm spectral range.…”