arXiv subjects

Jian Guo Wang

Publications and source records attributed to Jian Guo Wang.

5 recordsLinked to original sources

arXiv2026

Plasma Screening Effects in Stark Broadening: A Fully Relativistic Close-Coupling Approach

Stark broadening of spectral lines in plasmas is a cornerstone of opacity modeling and plasma diagnostics, with critical implications for controlled fusion and astrophysics. Despite recent advances in fully quantum-mechanical close-coupling calculations for electron-impact broadening, the impact of denser plasma environments remains largely unexplored due to theoretical bottlenecks associated with electron-ion collision processes. Based on our newly developed close-coupling theory for electron-ion collisions in plasmas, which resolves the problem of extracting short-range scattering phase shifts, we introduce a fully relativistic close-coupling approach for the Stark broadening that incorporates plasma screening effects. Systematic investigations of hydrogenic radiators reveal distinct patterns of line broadening dependence on plasma conditions, offering valuable insights for plasma diagnostic applications. Furthermore, we provide a quantum-mechanical interpretation of the screening factor commonly introduced in semi-classical impact theories. This work establishes a robust foundation for future studies on complex atomic systems in high-density plasmas.

physics.plasm-ph↗

arXiv2026

R-Matrix Theory for Electron-Ion Collisions in Plasmas

Electron-atom collisions in warm dense plasmas are crucial for astrophysics and controlled fusion research, where calculating short-range scattering matrices under screening plasma potentials is essential. While electron-neutral atom collisions are tractable using the standard Riccati-Bessel wavefunctions in the asymptotic region, electron-ion collisions face challenges due to the extended range of the screened Coulomb potential, which lacks analytical solutions or numerical code packages for asymptotic regular and irregular wavefunctions. We introduce an R-matrix theoretical framework for general screened potentials and develop a numerical method to compute these asymptotic wavefunctions efficiently. Our approach yields short-range scattering phase shifts that remain invariant with respect to the matching point in the asymptotic region. Applying the Debye screening potential as an illustrative example, we calculate elastic and electron-impact excitation collision strengths for H-like ions (He, C, Ne) across varying temperatures and densities. The calculations show that Debye screening systematically modifies resonance structures and progressively lowers excitation thresholds. Nevertheless, the effective collision strengths and rate coefficients exhibit approximate scaling laws. These findings enable convenient access to electron collision data in plasma environments, advancing plasma diagnostics and modeling.

physics.atom-ph↗

arXiv2023

On the formation of metallic glass

The high cooling rate needed for preparing the metallic glass (MG) makes the nonequilibrium nature of glass formation more prominent and requires a better quenching technique than ever before. Here, we formulate the cooling process in an analytical way and figure out the determinants for cooling rate, and analyze the crystallization time with consideration of phase diagram. Based on the reduced glass transition temperature, Trg, for measuring the glass-forming ability (GFA), a more reasonable ΔTrg is proposed. Glass transition, especially in ever glass whose ground state is of glass, is discussed in terms of thermodynamics for phase transition. A fundamental law concerning the changing rate of entropy in a closed system is supposed to underlie the physics for glass formation. These results may help understand the glass formation principally and develop new and robust MGs technically.

cond-mat.mtrl-sci↗

arXiv2018

Resonances in nonrelativistic free-free Gaunt factors with screened Coulomb interaction

The effect of Coulomb interaction screening on non-relativistic free-free absorption is investigated by integrating the numerical continuum wave functions. The screened potential is taken to be in Debye-Hűckel (Yukawa) form with a screening length D. It is found that the values of the free-free Gaunt factors for different Debye screening lengths D for a given initial electron energy \eps_i and absorbing photon energy ω, generally lie between those of the pure Coulomb field and field-free case. However, for initial electron energies below 0.1 Ry and fixed photon energy, the Gaunt factors show dramatic enhancements (broad and narrow resonances) in the vicinities of the critical screening lengths, Dnl, at which the energies of nl bound states in the potential merge into the continuum. These enhancements of the Gaunt factors can be significantly higher than their values in the unscreened (Coulomb) case over a broad range of \eps_i. The observed broad and narrow resonances in the Gaunt factors are related to the temporary formation of weakly bound (virtual) and resonant (quasi-bound) states of the low-energy initial electron on the Debye-Hűckel potential when the screening length is in the vicinity of Dnl.

physics.atom-ph↗

arXiv2016

A review of quantum collision dynamics in Debye plasmas

Hot, dense plasmas exhibit screened Coulomb interactions, resulting from the collective effects of correlated many-particle interactions. In the lowest particle correlation order (pair-wise correlations), the interaction between charged plasma particles reduces to the Debye-Hückel (Yukawa-type) potential, characterized by the Debye screening length D. Due to the importance of Coulomb interaction screening in dense laboratory and astrophysical plasmas, hundreds of theoretical investigations have been carried out in the past few decades on the plasma screening effects on the electronic structure of atoms and their collision processes employing the Debye-Hückel screening model. The present article aims at providing a comprehensive review of the recent studies in atomic physics in Debye plasmas. Specifically, the work on atomic electronic structure, photon excitation and ionization, electron/positron impact excitation and ionization, and excitation, ionization and charge transfer of ion-atom/ion collisions will be reviewed.

physics.atom-ph↗