M. Klapisch

Quenching of transition arrays through configuration mixing

In the atomic central-field model, the cancellation of some electric-dipole line strengths is a well known effect of configuration mixings. The authors study their global effects on transition arrays. A crucial quantity is the wavenumber mu 1 of the centre of gravity of two transition arrays when their upper or lower configurations mix. A closed formula is derived for the difference delta Emix between the values of mu 1 with and without the mixing effects. Two experimental examples are presented. In the first one, the value of delta Emix is a sufficient proof that one of the two arrays is almost completely quenched by the other. In the second one, the quenching is only partial, and the degree of quenching is evaluated. In conclusion using the unresolved transition array (UTA) formalism, it is possible to determine ab initio the centre of gravity of a mixed array, without any need for diagonalisation, and to deduce the main effects of configuration mixing.

Identification of Mo XV to Mo XXXIII in the soft X-ray spectrum of the TFR Tokamak

Abstract Lines of highly ionized molybdenum (originating from the limiter) were observed in the TFR spectrum between 5 and 50 A. Identification was performed by comparison with a spark spectrum and ab initio relativistic calculations.

Identification of the spectra of Hf xlv, Ta xlvi, W xlvii, and Re xlviii isoelectronic to Ni i in laser- produced plasmas

The x-ray spectra in the range 5–8 A emitted from laser-produced plasmas of Hf, Ta, W, and Re were observed. Lines belonging to the 3d10 − 3d9 4f and 3d10 − 3d9 4p transitions, as well as the 3p63d10 − 3p53d10 4s and 3p63d10 − 3p53d10 4d transitions in the Ni-like isoelectronic sequence, were identified. In addition, the interpretation of some previously measured lines of the same sequence were revised.

Mean wavelength and spectral width of transition arrays in x-uv atomic spectra

Formulas have been derived for the averages and widths of the distributions of energy levels and line wave numbers in atomic spectra. For some types of transitions, the mean wave number is not equal to the difference of the energy averages of the configurations. Allowance for this effect improves the interpretation of highly ionized Mo spectra.

Classification of X-Ray Spectra from Laser Produced Plasmas of Atoms from Tm to Pt in the Range 6-9 Å

X-ray spectra of highly ionized tungsten and neighbouring atoms (Tm, Yb, Hf, Ta, W, Re and Pt) has been observed from laser produced plasmas in the λ = 6-9 A range. Beside the prominent lines of the Ni I-like ions, lines belonging to Co I (3d9-3d84p), Cu I (3d104s-3d94s4p, 3d104p-3d94p2) and Zn I-like ions (3d104s2-3d94s24p, 3d104s4p-3d94s4p2) have been identified. Classification was based on isoelectronic sequence analysis and on comparison with ab-initio relativistic calculations. A collisional-radiative model of the Cu I-like ions in the plasma is used to show that the contribution of the 3d104d-3d94p4d and 3d104f-3d94f4p transition arrays to the 3d-4p spectrum is small. The importance of configuration interaction is pointed out. Computations agree with measurements within experimental uncertainty.

The Unresolved 3d-4f Transitions in the X-ray Spectra of Highly Ionized Tm to Re from Laser Produced Plasma

The broad, characteristic, pseudo-continua appearing in many spectra of highly ionized heavy atoms (5-8 A) are interpreted as superpositions of Spin-Orbit-Split Arrays, a particular case of Unresolved Transition Arrays for which formulas have been published recently. They pertain to 3d-4f transitions in atoms isoelectronic to Cu, Zn, Ga and Ge. Some individual lines belonging to the Co sequence are also identified. Effects of departure from pure jj coupling are discussed.

Nickel-like spectra of elements Y xii to Ag xx from a vacuum spark

The spectra of elements Y, Zr, Nb, Mo, Ru, Rh, Pd, and Ag in the 10–100-A range were obtained from a high-power vacuum spark and a grazing-incidence high-resolution spectrograph. The transitions 3d10–3d94p, 3d10–3d94f, 3d10–3d95p, and 3d10–3d95f were identified. The agreement with ab initio relativistic calculations is good. The relevance of the jj coupling scheme for level labeling is discussed, as is the importance of relativistic effects, by comparing the scheme with other results on high-Z atoms (up to Pt).

Soft X-ray bands of highly ionized tungsten, gold and lead emitted by the TEXT tokamak plasma☆

Spectra of highly ionized tungsten, gold and lead emitted from the TEXT tokamak have been recorded in the 20–70 A range by means of a grazing incidence, time-resolving spectrograph. The narrow and bright emission bands centered around 40, 45 and 50 A in Pb, Au and W respectively, and bands of lesser intensities at lower wavelenghts, are emitted by a very large number of superimposed lines originating from transitions of the type 4d104fn−4d94fn+1, 4d104fn−4d94fn5p and 4fn−4fn−15l (l=d, g). The isoelectronic analysis shows that at the electron temperatures prevailing in the present experiment, Te≈800 eV, there are no contributions to the bands from ions having a 4p64dn ground state. This, together with the experimental measurement of the electron temperature profile, indicates that the heavy ion impurity distribution in the tokamak plasma is very close to ionization equilibrium.

Identification of magnetic quadrupole lines of highly ionized Ni, Cr, Fe in the TFR600 Tokamak plasma

Abstract Forbidden lines (magnetic quadrupole) in spectra of NeI like CrXV, FeXVII and NiXIX, were identified in the TFR600 Tokamak plasma, in the 10–20 A range.

The spectrum of highly ionized praseodymium and dysprosium from the Texas tokamak plasma in the 50–250‐Å range

Spectra of highly ionized praseodymium and dysprosium recorded from the Texas tokamak (TEXT) plasma have been analyzed in the 50–250‐A range. The spectra contain high‐intensity continuum bands in the region below 100 A and bright individual lines above this wavelength. Lines of highly ionized praseodymium and dysprosium have been identified. The highest ionization state reached in the 1‐keV central electron temperature tokamak plasma was Cu i‐like Pr xxxi. The composition of the bands is explained in terms of a new theoretical approach developed to treat large unresolved transition arrays. The brightness of the continuum is compared with that of intense spectral lines emitted in the same wavelength range.