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New X-ray observatories (Chandra and XMM-Newton) are providing a wealth of high-resolution X-ray spectra in which hydrogen- and helium-like ions are usually strong features. We present results from a new collisional-radiative plasma code,…

Astrophysics · Physics 2009-11-06 Randall K. Smith , Nancy S. Brickhouse , Duane A. Liedahl , John C. Raymond

An experimental study of laser driven electron acceleration in N2 and N2-He mixed gas-jet target using laser pulses of duration ~60-70 fs is presented. Generation of relativistic electron beam with quasi-thermal spectra was observed at a…

Plasma Physics · Physics 2020-01-08 D. Hazra , A. Moorti , S. Mishra , A. Upadhyay , J. A. Chakera

We have measured resonance strengths and energies for dielectronic recombination (DR) of Mg-like Fe XV forming Al-like Fe XIV via N=3 -> N' = 3 core excitations in the electron-ion collision energy range 0-45 eV. All measurements were…

We present observations of SS 433 using the Chandra High Energy Transmission Grating Spectrometer. Many emission lines of highly ionized elements are detected with the relativistic blue and red Doppler shifts. The lines are measurably…

Astrophysics · Physics 2009-11-07 Herman L. Marshall , Claude R. Canizares , Norbert S. Schulz

A new limit on the possible cosmological variation of the proton-to-electron mass ratio \mu=m_p/m_e is estimated by measuring wavelengths of H_2 lines of Lyman and Werner bands from two absorption systems at z_abs = 2.5947 and 3.0249 in the…

Astrophysics · Physics 2009-11-13 A. Ivanchik , P. Petitjean , D. Varshalovich , B. Aracil , R. Srianand , H. Chand , C. Ledoux , P. Boisse

Recent calculations of atomic data for Fe XV have been used to generate theoretical line ratios involving n = 3-4 transitions in the soft X-ray spectral region (52-83 A), for a wide range of electron temperatures and densities applicable to…

The Airborne Infrared Spectrometer (AIR-Spec) offers an unprecedented opportunity to explore the Near Infra-Red (NIR) wavelength range. It has been flown at two total solar eclipses, in 2017 and 2019. The wavelength range of the much…

Solar and Stellar Astrophysics · Physics 2023-03-01 G. Del Zanna , J. Samra , A. Monaghan , C. Madsen , P. Bryans , E. DeLuca , H. Mason , B. Berkey , A. de Wijn , Y. Rivera

Recently an accurate analysis of absorption spectra of molecular hydrogen, observed with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope, in the photosphere of white dwarf stars GD133 and GD29-38 was published in a Letter…

Atomic Physics · Physics 2015-06-23 E. J. Salumbides , J. Bagdonaite , H. Abgrall , E. Roueff , W. Ubachs

We measured for the first time the electron density in an Extreme Ultra-Violet induced plasma. This is achieved in a low-pressure argon plasma by using a method called microwave cavity resonance spectroscopy. The measured electron density…

Plasma Physics · Physics 2014-07-07 R. M. van der Horst , J. Beckers , S. Nijdam , G. M. W. Kroesen

The ion populations most frequently adopted for diagnostics in collisional plasmas are derived from the density independent, coronal approximation. In higher density, lower temperature conditions, ionisation rates are enhanced once…

Solar and Stellar Astrophysics · Physics 2020-07-22 R. P. Dufresne , G. Del Zanna , N. R. Badnell

We have carried-out multi-configuration Breit-Pauli AUTOSTRUCTURE calculations for the dielectronic recombination (DR) of Fe^{8+} - Fe^{12+} ions. We obtain total DR rate coefficients for the initial ground-level which are an order of…

Astrophysics · Physics 2010-11-11 N. R. Badnell

In transition-metal compounds, the transition-metal d electrons play an important role in their physical properties; however, the effects of the electron correlation between the ligand p electrons have not been clear yet. In this Letter,…

We observed spectra of highly ionized tungsten in the extreme ultraviolet with an electron beam ion trap (EBIT) and a grazing incidence spectrometer at the National Institute of Standards and Technology. Stages of ionization were…

Atomic Physics · Physics 2008-01-21 Yu. Ralchenko , J. Reader , J. M. Pomeroy , J. N. Tan , J. D. Gillaspy

The distribution of the coronal electron density at different distances from the Sun strongly influences the physical processes in the solar corona and is therefore a very important topic in solar physics. Most methods, including radio…

Most treatments of electron-electron correlations in dense plasmas either ignore them entirely (random phase approximation) or neglect the role of ions (jellium approximation). In this work, we go beyond both these approximations to derive…

Plasma Physics · Physics 2020-02-05 Nathaniel R. Shaffer , Charles E. Starrett

We report calculations of energy levels, radiative rates, and electron impact excitation rates for transitions in Li-like ions with 12 <= Z <= 20. The GRASP (general-purpose relativistic atomic structure package) is adopted for calculating…

Atomic and Molecular Clusters · Physics 2015-06-05 K. M. Aggarwal , F. P. Keenan

We present a review of two methods used to model recent LCLS experimental results for the 3C/3D line intensity ratio of Fe XVII (Bernitt et al. 2012), the time-dependent collisional-radiative method and the density-matrix approach. These…

Atomic Physics · Physics 2017-10-11 Y. Li , M. Fogle , S. D. Loch , C. P. Ballance , C. J. Fontes

The Numerical Advanced Model of Electron Cyclotron Resonance Ion Source (NAM-ECRIS) is applied for studies of the physical processes in the source. Solutions of separately operating electron and ion modules of NAM-ECRIS are matched in…

Plasma Physics · Physics 2020-08-26 V. Mironov , S. Bogomolov , A. Bondarchenko , A. Efremov , V. Loginov , D. Pugachev

Weakly collisional Ar-O2 electronegative plasmas are investigated in a dc multidipole chamber. An electronegative core and an electropositive halo are observed. The density ratio of negative ions to electrons ({\alpha}) in the nondrifting…

Plasma Physics · Physics 2015-06-04 Y. -C. Ghim , N. Hershkowitz

Simple analytic formulae for energy relaxation (ER) in electron-ion systems, with quantum corrections, ion dynamics and RPA-type screening are presented. ER in the presence of bound electrons is examined in view of of recent simulations for…

Plasma Physics · Physics 2008-11-26 M. W. C. Dharma-Wardana