J. L. Schwob

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.

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.

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).

X ray and EUV spectroscopic measurements of highly charged tungsten ions relevant to fusion plasmas

Using high-resolution x ray and extreme ultraviolet (EUV) spectrometry, the line emission of W28+ - W50+ ions was measured at the Berlin Electron Beam Ion Trap (EBIT). Our study encompasses a wide range of wavelengths (5-800 A) and includes the observation of electric and magnetic dipole lines. The results of our measurements are compared with predicted transition wavelengths from ab initioatomic structure calculations.

The 3d9-3d84p Transitions in the Spectra of Highly-Ionized Elements Yttrium to Silver (Y XIII-Ag XXI)

Two hundred and ninety-five lines of the spectra of cobalt-like ions Y XII, Zr XIV, Nb XV, Mo XVI, Ru XVIII, Rh XIX, Pd XX and Ag XXI have been classified as 3d9-3d84p transitions. They involve 250 energy levels which are described by 21 parameters with a root-mean-square deviation of 290 cm-1. The scaling factors of radial integrals calculated by the Hartree-Fock method have been fitted as well as effective electrostatic parameters. The validity of the results is based on isoelectronic regularities and has been checked by extrapolations to the known spectra of Br IX and Sn XXIV. Predictions are given for Kr X, Rb XI, Sr XII, Cd XXII and In XXIII.

The x-ray emission spectra of multicharged xenon ions in a gas puff laser-produced plasma

Emission spectra of multicharged xenon ions produced by a laser gas puff are observed with high spectral resolution in the 8.5-9.5 and 17- wavelength ranges. Three different theoretical methods are employed to obtain 3l- ( to 10) wavelengths and Einstein coefficients for Ni-like . For the 3d-4p transitions, very good agreement is found between the experimental wavelengths and the various theoretical wavelengths. These accurate energy level measurements can be useful for studying the Ni-like xenon x-ray laser scheme. On the other hand, several intense spectral lines could not be identified as 3l- lines of Ni-like xenon, despite the very good agreement between the wavelengths and Einstein coefficients calculated for these transitions using the three different methods.

Dielectronic recombination of Ni-, Cu-, and Ar-like tungsten and barium through the low inner-shell excited configurations including collision processes

Level-by-level relativistic calculations of dielectronic recombination (DR) cross sections and rate coefficients for Ni-, Cu-, and Ar- like tungsten in the ground state were performed. Similar calculations were carried out for Ni-like barium for comparison. The most important low-lying inner-shell excited configuration complexes are taken into account, namely (3p3d)154141′ for Ni-like W and Ba, (3p3d)154s4141′ for Cu-like W, and finally 3p53d91, 3s3p63d71, and 3p54141′ for Ar-like W. These complexes give the dominant contributions to the total DR rate coefficients for kTe < 0.5 keV, and are still expected to give major contributions at higher electron temperature. Configuration mixing is taken into account when significant. The energy levels of the tungsten inner-shell excited DR channels are found to have typical j-j coupling characteristics, whereas those of Ni-like barium do not. The role of non-resonant radiative stabilizations is found to be generally minor for the Ni- and Cu-like ions. In contrast, for Ar-like tungsten these stabilizations are found to be very important. The DR rate coefficients for Cu-like tungsten are found to be very close in magnitude to those of the Ni-like ion. Some partial contributions to the DR rate coefficients are found to rise dramatically at very low electron temperature, a fact that has been observed experimentally for lighter ions. It is found that high-1 3p53d91 configurations, that were previously neglected, may have a significant contribution to the DR of Ar-like tungsten. The effect of electron collisions with the inner-shell excited ions is shown to influence the DR rate coefficient only at very high electron densities, greater than 1020 cm−3 for Ni-like W and greater than 1022 cm−3 for Ar-like W. In the Ni-like case at an electron density of 1023 cm−3 these collisions enhance the DR rate by about 30% at 5 keV, and by as much as a factor of 2 at 200 eV.

Analysis of the x-ray spectra emitted by laser-produced plasma of highly ionized lanthanum and praseodymium in the 8.4 to 12.0 Å wavelength range

A detailed analysis of the x-ray spectra emitted by laser produced plasma of lanthanum (8.5-12.5 A) and praseodymium (8.4-11.3 A) is given, using ab-initio calculations with the HULLAC relativistic code. Resonance 3d-nf (n = 4, 5, 6) and 3p-4s, 4d transitions of the La XXX and Pr XXXII Ni I-like ions and neighbouring ionization states (La XXVIII to La XXXVI, Pr XXX to Pr XXXVI) have been identified.

Cr, Co, and Ni transitions isoelectronic to the Fe xxiv – Fe xvii lines around 11 Å in laser-produced plasma

The laser-produced plasma spectra of Cr, Co, and Ni observed between 9 and 14 A isoelectronic to the iron lines in the wavelength region 10.5–12 A are measured. Spectral lines belonging to many ionization stages fall in this wavelength region. Classification of most of these lines is given, based on isoelectronic extrapolation with comparison to other works on iron.