Anisotropic<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>L</mml:mi><mml:mi>M</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:math>dielectronic resonances from ratios of magnetic-dipole lines

Ralchenko, Yu.; Gillaspy, John D.

doi:10.1103/physreva.88.012506

Cited by 10 publications

(13 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to calculate the spectral line intensities in the measured range of wavelengths, we carried out collisional-radiative (CR) modeling of the Ba plasma. The modeling was performed with the CR code NOMAD [12] that has been extensively used for non-Maxwellian EBIT simulations [9,13,14]. The radiative and collisional data, such as level energies, radiative transition probabilities and electron-impact cross sections for excitation, de-excitation, ionization, and radiative recombination, were calculated with the Flexible Atomic Code (FAC) [15].…”

Section: Collisional-radiative Modeling and Line Identificationsmentioning

confidence: 99%

Extreme ultraviolet spectra and analysis ofΔn= 0 transitions in highly charged barium

Reader

Gillaspy

Osin

et al. 2014

J. Phys. B: At. Mol. Opt. Phys.

View full text Add to dashboard Cite

Extreme ultraviolet spectra of highly charged barium atoms were produced with an electron beam ion trap (EBIT) and recorded with a flat-field grazing-incidence spectrometer. The spectra were measured in the wavelength range 4 nm-24 nm with the beam energies varying from 700 eV to 30 000 eV. The line identifications were performed with collisional-radiative modeling of the EBIT plasma that provided good quantitative agreement between simulated and measured spectra. In the energy range 700 eV-1750 eV, fifty three n = 4-n = 4 transitions in Se-like (Ba 22+) to Cu-like (Ba 27+) ions were identified, with forty seven corresponding to new lines. Almost all lines are due to electric-dipole transitions. For the beam energies of 3945 eV-7530 eV, we identified eight new n = 3-n = 3 transitions in Ba 42+ (Si-like), Ba 43+ (Al-like), and Ba 44+ (Mglike). At the highest beam energy, 30 000 eV, three new n = 2-n = 2 transitions of Ba 51+ (B-like), Ba 52+ (Be-like), and Ba 53+ (Li-like) were identified. The measured wavelengths are compared with recent ab initio theoretical calculations. An improved ionization energy for Ba 26+ (Zn-like), IE = 937.2 ± 0.8 eV, was determined by comparing theoretical values with measurements along the Zn isoelectronic sequence.

show abstract

Section: Collisional-radiative Modeling and Line Identificationsmentioning

confidence: 99%

Extreme ultraviolet spectra and analysis ofΔn= 0 transitions in highly charged barium

Reader

Gillaspy

Osin

et al. 2014

J. Phys. B: At. Mol. Opt. Phys.

View full text Add to dashboard Cite

show abstract

“…Moreover, DR has been known as one of the important recombination processes, which plays dominant roles in the ionization equilibrium of various plasmas. Triggered by this, much work on the DR process and the rate coefficients of tungsten ions has been done, both theoretically and experimentally [39][40][41][42][43][44][45][46][47][48][49][50]. For example, the Atomic Data and Analysis Structure (ADAS) database is currently used for modeling plasmas in the community [7,42,51,52].…”

Section: Introductionmentioning

confidence: 99%

Electron Impact Excitation and Dielectronic Recombination of Highly Charged Tungsten Ions

et al. 2015

Atoms

View full text Add to dashboard Cite

Electron impact excitation (EIE) and dielectronic recombination (DR) of tungsten ions are basic atomic processes in nuclear fusion plasmas of the International Thermonuclear Experimental Reactor (ITER) tokamak. Detailed investigation of such processes is essential for modeling and diagnosing future fusion experiments performed on the ITER. In the present work, we studied total and partial electron-impact excitation (EIE) and DR cross-sections of highly charged tungsten ions by using the multiconfiguration Dirac-Fock method. The degrees of linear polarization of the subsequent X-ray emissions from unequally-populated magnetic sub-levels of these ions were estimated. It is found that the degrees of linear polarization of the same transition lines, but populated respectively by the EIE and DR processes, are very different, which makes diagnosis of the formation mechanism of X-ray emissions possible. In addition, with the help of the flexible atomic code on the basis of the relativistic configuration interaction method, DR rate coefficients of highly charged W 37+ to W 46+ ions are also studied, because of the importance in the ionization equilibrium of tungsten plasmas under running conditions of the ITER.

show abstract

“…Only very few studies of x-ray polarization and angular distributions have been performed for astrophysically relevant ions using electron beam ion traps (EBITs) [38][39][40][41][42][43][44][45][46]. Other studies with EBITs [47][48][49][50], electron accelerators [32,51,52] and storage ring [34,53] have focused on heavy ionic systems. Moreover, the photoelectric gas polarimeter [4,54] of the XIPE mission will not resolve individual x-ray transitions.…”

mentioning

confidence: 99%

Strong higher-order resonant contributions to x-ray line polarization in hot plasmas

et al. 2016

View full text Add to dashboard Cite

We studied angular distributions of x rays emitted in resonant recombination of highly charged iron and krypton ions, resolving dielectronic, trielectronic, and quadruelectronic channels. A tunable electron beam drove these processes, inducing x rays registered by two detectors mounted along and perpendicular to the beam axis. The measured emission asymmetries comprehensively benchmarked full-order atomic calculations. We conclude that accurate polarization diagnostics of hot plasmas can only be obtained under the premise of inclusion of higher-order processes that were neglected in earlier work. 32.30.Rj, 31.30.jc, 34.80.Lx The observation of x-ray polarization in emissions from the Crab Nebula [1,2], with synchrotron radiation as its origin, fueled a strong interest in the astrophysics community for launching an x-ray polarimetry (XRP) mission [3][4][5][6][7]. X-ray Imaging Polarimetry Explorer (XIPE) has recently been selected as one of three candidates for the next medium-size satellite mission by the European Space Agency ESA. Its aim is studying the anisotropies of astrophysical plasmas which are found in the most extreme yet poorly understood sites in the Universe [8,9]. Up to now anisotropic plasmas were found in active galactic nuclei [10][11][12], pulsars [13], gamma-ray bursts [14][15][16], neutron stars [17,18], and solar flares [19][20][21]. They appear prominently also in the laboratory: in experiments with strong lasers [22,23], magnetic cusps [24], z -pinches [25], and fusion devices [25][26][27] such as tokamaks [28][29][30] and stellarators. The directionality of the electron-ion collisions leaves an imprint in the polarization of the plasma x rays [31][32][33][34][35][36]. Polarization measurements may therefore reveal the presence and orientation of particle beams, magnetic fields and, hence, provide information on the plasma heating and confinement mechanisms [25][26][27] in instances where spatial resolution is insufficient. In astrophysics, indeed, XRP is often the only technique for deriving information on the geometry of angularly unresolved sources [8,37].Ideally, the XRP data should be analyzed with detailed knowledge of the atomic polarization mechanisms. Until now, however, no or little experimental information is available for most atomic processes. Only very few studies of x-ray polarization and angular distributions have been performed for astrophysically relevant ions using electron beam ion traps (EBITs) [38][39][40][41][42][43][44][45][46]. Other studies with EBITs [47][48][49][50], electron accelerators [32, 51, 52] and storage ring [34,53] have focused on heavy ionic systems. Moreover, the photoelectric gas polarimeter [4,54] of the XIPE mission will not resolve individual x-ray transitions. This limitation is rather general, even if high resolution detectors were used, since Doppler shifts will most likely blur the signal. Thus, the polarization signal will contain contributions from many transitions and continuum radiation due to bremsstrahlung and recombination of plas...

show abstract

AnisotropicLMNdielectronic resonances from ratios of magnetic-dipole lines

Cited by 10 publications

References 44 publications

Extreme ultraviolet spectra and analysis ofΔn= 0 transitions in highly charged barium

Extreme ultraviolet spectra and analysis ofΔn= 0 transitions in highly charged barium

Electron Impact Excitation and Dielectronic Recombination of Highly Charged Tungsten Ions

Strong higher-order resonant contributions to x-ray line polarization in hot plasmas

Contact Info

Product

Resources

About