Atomic calculation for Fe XXIII, UV, and X-ray lines
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Bhatia, A. K.↗
Engineering topics
Bhatia, A. K.
Publications and source records attributed to Bhatia, A. K..
Quasi-projection-operator calculation of autoionization states of O5/+/ /O VI/ and Si11/+/ /Si XII/
A practical approach to calculating diagnostic parameters includes both scattering and statelike (autoionization) elements. The paper presents inelastic quasi-projection-operator calculations of autoionization states of the three-electron ions of oxygen and silicon for states below the n = 3 manifod of the respective two-electron parent (O VI and Si XII). Wave functions containing up to 40 configurations are calculated. The O VI calculated results agree with experimental results within the experimental error (about + or - 2 eV) while for the Si XII case, it was necessary to include relativistic effects. Where formulas are available (states for which p + q = 2), the Si XII results are also in good agreement with experimental results for 2Se, 2Po, and 2De states. Since the calculated results for some of the higher states did not agree with identifications proposed by Trabert et al. (1979), alternative identifications are suggested.
Wakid, S.↗
Use of generalized population ratios to obtain Fe XV line intensities and linewidths at high electron densities
A generalized method for obtaining individual level population ratios is used to obtain relative intensities of extreme ultraviolet Fe XV emission lines in the range 284-500 A, which are density dependent for electron densities in the tokamak regime or higher. Four lines in particular are found to attain quite high intensities in the high-density limit. The same calculation provides inelastic contributions to linewidths. The method connects level populations and level widths through total probabilities t(ij), related to 'taboo' probabilities of Markov chain theory. The t(ij) are here evaluated for a real atomic system, being therefore of potential interest to random-walk theorists who have been limited to idealized systems characterized by simplified transition schemes.
Kastner, S. O.↗
New approach to hyperfine structure - Application to the Li ground state
Global identities for delta functions, given by Hiller, Sucher and Feinberg (HSF) are applied to the calculation of the hyperfine structure (HFS) of the ground state of Li. It is shown that use of the HSF identity together with configuration interaction type wavefunctions can yield values of the HFS constant f which are comparable in accuracy to that obtained by Larsson with a 100-term Hylleraas-type wavefunction. The implications of this result for HFS calculations for atoms with many electrons are discussed.
Bhatia, A. K.↗
Atomic parameters for Fe/XV/ and Ni/XVII/
Transition probabilities and oscillator strengths have been obtained in a study of the magnesium-like ions Fe(XV) and Ni(XVII). Some of the atomic parameters developed are tabulated in this work.
Bhatia, A. K.↗
Electron-impact excitation of Li II in the distorted-wave approximation
The 1(1)S yields 2(3)P electron-impact-excitation cross section for Li II is calculated in the distorted-wave approximation. Two forms of the distorted-wave method are examined; in the first form both the initial and final wave functions are distorted, while in the second form only the initial wave function is distorted. In both forms a partial-wave expansion of the scattered amplitude is made, and exchange is incorporated in a consistent manner. The effects of including more than one configuration in the target-state wave function are also examined. For incident energies greater than 90 eV, distorted-wave calculations agree moderately well with recent experimental and theoretical results.
Pindzola, M. S.↗
Atomic data for S IV and solar observations of the 3x/2/3p /2/P-3s3p/2/ /4/P multiplet
High resolution observations of intersystem lines of S IV near 1400 A are available from Skylab. These lines are potentially useful as density diagnostics for the solar atmosphere. Energy levels, transition probabilities and collision strengths have, therefore, been calculated for S IV, including the configurations 3x(2)3p, 3s3p(2), and 3s(2)3d. Line intensities and level populations have been calculated as a function of electron density. The calculated population of the 3s3p(2) (4)P(5/2) level is found to reach a pseudo-Boltzmann equilibrium at a density which is four times higher than is inferred from solar spectra and level population calculations of lighter ions such as O IV.
Bhatia, A. K.↗
Parity-violating electric-dipole transitions in helium
The paper examines parity-violating electric-dipole transitions in He in order to gain insight into the reliability of approximate calculations which are carried out for transitions in many-electron atoms. The contributions of the nearest-lying states are computed with a variety of wave functions, including very simple product wave functions, Hartree-Fock functions and Hylleraas-type wave functions with up to 84 parameters. It is found that values of the matrix elements of the parity-violating interaction can differ considerably from the values obtained from the good wave functions, even when these simple wave functions give accurate values for the matrix elements in question
Hiller, J.↗
Theoretical atomic structure and electron scattering data for ions in the nitrogen isoelectronic sequence - Mg VI, Si VIII, S X, A XII and Ca XIV
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Bhatia, A. K.↗
New atomic data for Fe/+19/
New atomic data are tabulated for Fe(+19). The electron collision strengths are calculated using the 'distorted wave' approximation and results are presented for several energies of the exciting electron. The populations of the ground levels are calculated as a function of electron density under conditions appropriate to solar flares and tokamak plasmas. Theoretical intensity ratios are tabulated for the UV lines.
Bhatia, A. K.↗
Atomic data and level populations of highly ionized Ti for tokamak plasmas
The paper presents calculations of electron impact collision strengths and spontaneous radiative decay rates for titanium ions of the LiI through FI isoelectronic sequences for transitions between levels of the 2S(2)2p(k), 2s2p(k+1), and 2p(k+2) configurations. From these atomic data, excitation-rate coefficients are calculated along with level populations for these three configurations. The calculations of level populations include the effects of proton excitation, and are carried out at electron temperatures and densities typical of tokamak plasmas. Wavelengths of forbidden and intersystem lines are given, and a synthetic spectrum is presented for a typical temperature and density.
Bhatia, A. K.↗
The coronal spectra of Fe XV and Ni XVII
Predicted allowed and forbidden EUV line intensities of Fe XV and Ni XVII are presented in explicit graphical form, clarifying and extending the earlier treatment of Bely and Blaha (1968). In the case of the former ion a detailed comparison with available observations leads to questioning or rejection of some presently accepted line identifications (323.57 A, 317.61 A), and on the other hand suggests that a quiet sun line at 304.853 A is due to Fe XV. For the little known ion Ni XVII estimates of level structure and line wavelengths are given and a preliminary comparison is made with recent flare observations.
Bhatia, A. K.↗
Quasi-projection-operator calculation of inelastic resonances in He/-/ and Li
Feshbach resonances of electrons incident of He and Li(+) are calculated below the 3(S-3) target threshold by means of the inelastic quasi-projection-operator technique of Temkin and Bhatia (1972). A configuration-interaction-type wave function is employed with up to 46 configurations. The calculations reveal, with reasonable accuracy, all presently observed Feshbach resonances. The method does not reveal shape resonances, but, for isoelectronic systems with greater nuclear charge, it is argued that shape resonance should become less important. This is already apparent in the case of Li, for which the known resonances are calculated and higher resonances, for which there are as yet no experimental data, are predicted.
Wakid, S.↗
Spectroscopy and atomic physics of highly ionized Cr, Fe, and Ni for tokamak plasmas
The paper considers the spectroscopy and atomic physics for some highly ionized Cr, Fe, and Ni ions produced in tokamak plasmas. Forbidden and intersystem wavelengths for Cr and Ni ions are extrapolated and interpolated using the known wavelengths for Fe lines identified in solar-flare plasmas. Tables of transition probabilities for the B I, C I, N I, O I, and F I isoelectronic sequences are presented, and collision strengths and transition probabilities for Cr, Fe, and Ni ions of the Be I sequence are given. Similarities of tokamak and solar spectra are discussed, and it is shown how the atomic data presented may be used to determine ion abundances and electron densities in low-density plasmas.
Feldman, U.↗
New atomic data for Si/6+/, S/8+/ and Ar/10+/
The paper gives new atomic data, populations of excited levels, and line intensity ratios for the ions Si VII, S IX, and Ar XI of the O I isoelectronic sequence. Ten levels are included in the calculations, i.e., the levels of the 2s/2/2p/4/ and 2s2p/5/ and 2p/6/ configurations. It is noted that the calculations are done for applications to solar plasmas. The line ratios (2s/2/2p/4/3P1 - 2s2p/5/3P0) / (2s/2/2p/4/3P1 - 2s2p/5/3P1) and (2s/2/2p/4/1D2 - 2s2p/5/1P/1/) / (2s/2/2p/4/3P/1/ - 2s1p/5/3P/1/) are two of the ratios useful for electron density determination. Finally, density sensitive line ratios of Ca XIII and Fe XIX are also discussed.
Bhatia, A. K.↗
Level structure and predicted intercombination lines in magnesium-like V XII, Cr XIII, Mn XIV, and Co XVI
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Kastner, S. O.↗
New atomic data of O/2+/
New atomic data are tabulated for the ion O(2+). Collision strengths are calculated for several energies of the exciting electron. The populations of the levels of O(2+) are calculated as a function of electron density under conditions appropriate for the solar atmosphere. The available solar data are compared with theoretical predictions of relative line intensities.
Bhatia, A. K.↗
XUV electron density diagnostics for solar flares
Potential electron-density diagnostics for the high-temperature component of solar flares are studied with reference to the wavelength region from 171 to 630 A. The specific ions discussed include Fe IX through Fe XV, Ni XI through Ni XVII, and ions in the beryllium, boron, carbon, and nitrogen isoelectronic sequences. Line ratios that could be useful as density indicators under solar-flare conditions are indicated, available data for the ions considered are reviewed, and several theoretical intensity ratios are plotted. The results are employed to determine the electron-density distribution as a function of electron temperature for several spectra from two flares. For these flares it is found that the electron density increases from 10 billion to 500 billion per cu cm for a temperature increase from 1 million to 10 million K.
Dere, K. P.↗