http://ieeexplore.ieee.org/iel5/4639142/31561/01472527.pdf

Controlled fusion

https://aip.scitation.org/doi/pdf/10.1016/j.mre.2016.10.002

Review of quantum collision dynamics in Debye plasmas

Theoretical opacities are required for calculating energy transport in plasmas. In particular, understanding stellar interiors, inertial fusion, and Z pinches depends on the opacities of mid-atomic-number elements over a wide range of temperatures. The 150–300 eV temperature range is particularly interesting. The opacity models are complex and experimental validation is crucial. For example, solar models presently disagree with helioseismology and one possible explanation is inadequate theoretical opacities. Testing these opacities requires well-characterized plasmas at temperatures high enough to produce the ion charge states that exist in the sun. Typical opacity experiments heat a sample using x rays and measure the spectrally resolved transmission with a backlight. The difficulty grows as the temperature increases because the heating x-ray source must supply more energy and the backlight must be bright enough to overwhelm the plasma self-emission. These problems can be overcome with the new generation...

http://absimage.aps.org/image/DPP08/MWS_DPP08-2008-000780.pdf

Experimental investigation of opacity models for stellar interiors, inertial fusion, and high energy density 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-Huckel (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-Huckel 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.

A review of quantum collision dynamics in Debye plasmas

Critical parameters in three screened potentials, namely, Hulthen, Yukawa and exponential cosine screened Coulomb potential are reported. Accurate estimates of these parameters are given for each of these potentials, for all states having $n \leq 10$. Comparison with literature results is made, wherever possible. Present values compare excellently with reference values; for higher $n,\ell$, our results are slightly better. Some of these are presented for first time. Further, we investigate the spherical confinement of H atom embedded in a dense plasma modeled by an exponential cosine screened potential. Accurate energies along with their variation with respect to box size and screening parameter are calculated and compared with reference results in literature. Sample dipole polarizabilities are also provided in this case. The generalized pseudospectral method is used for accurate determination of eigenvalues and eigenfunctions for all calculations.

Critical parameters and spherical confinement of H atom in screened Coulomb potential

We present a detailed analysis of the plasma-induced resonance-like atomic structures near the ionization threshold in one- and two-photon ionization of hydrogen atom. Such resonance-like structures result from the migration of the upper bound excited states of bound-bound atomic transitions into the continuum due to the less attractive screened Coulomb potential which simulates the external environmental effect for an atom embedded in Debye plasma. The change from the resonance-like narrow structures into broad continuous spectra as the plasma effect increases could be accounted for by the overlap between the respective wavefunctions of the atomic electron in the initial state and its corresponding outgoing ionized state in the continuum.

/pdf/one-and-two-photon-ionization-of-hydrogen-atom-embedded-in-4bsqf5ejmh.pdf

One- and two-photon ionization of hydrogen atom embedded in Debye plasmas

In the present work, we present an investigation on quantum entanglement of the two-electron helium atom immersed in weakly coupled Debye plasmas, modeled by the Debye-Huckel, or screened Coulomb, potential to mimic the interaction between two charged particles inside the plasma. Quantum entanglement is related to correlation effects in a multi-particle system. In a bipartite system, a measurement made on one of the two entangled particles affects the outcome of the other particle, even if such two particles are far apart. Employing wave functions constructed with configuration interaction B-spline basis, we have quantified von Neumann entropy and linear entropy for a series of He 1,3Se and 1,3Po states in plasma-embedded helium atom.

Quantum entanglement for helium atom in the Debye plasmas

We present the results of a detailed theoretical study on the variation of the oscillator strengths for the 1 s → 2 p transition of the H-like ions and the 1 s 2 1 S → 1 s 2 p 1 P transition of the He-like ions (or, inversely, the Lyman-α and Heα emission lines, respectively) subject to external plasma which meet the spatial and temporal criteria of the Debye-Huckel (DH) approximation. Our study shows that the resulting oscillator strength decreases for the Heα line for He-like ions, similar to the Lyman-α emission lines for all H-like ions, as the effect of the external plasma increases with the decreasing Debye length D in terms of a reduced Debye length λ D = Z e f f D. A nearly universal feature is demonstrated for a scaled oscillator strength as a function of the reduced Debye length λD = (Z − 1)D for different He-like ions that meet the same criteria for the DH model. The percentage changes of the oscillator strengths from their plasma-free values are substantially greater than those for the corresponding change for the redshifts of the Lyman-α and Heα emission lines subject to outside dense plasma. Should these general features be demonstrated experimentally, the theoretical procedure presented in this study could easily be applied to extrapolate from a single calculation for one He-like ion to other He-like ions, which could offer an alternative to complement other diagnostic efforts of the dense plasma.We present the results of a detailed theoretical study on the variation of the oscillator strengths for the 1 s → 2 p transition of the H-like ions and the 1 s 2 1 S → 1 s 2 p 1 P transition of the He-like ions (or, inversely, the Lyman-α and Heα emission lines, respectively) subject to external plasma which meet the spatial and temporal criteria of the Debye-Huckel (DH) approximation. Our study shows that the resulting oscillator strength decreases for the Heα line for He-like ions, similar to the Lyman-α emission lines for all H-like ions, as the effect of the external plasma increases with the decreasing Debye length D in terms of a reduced Debye length λ D = Z e f f D. A nearly universal feature is demonstrated for a scaled oscillator strength as a function of the reduced Debye length λD = (Z − 1)D for different He-like ions that meet the same criteria for the DH model. The percentage changes of the oscillator strengths from their plasma-free values are substantially greater than th...

Variation of the oscillator strengths for the α emission lines of the one- and two-electrons ions in dense plasma

Redshift of the isolated atomic emission line in dense plasma

We present in this review our recent theoretical studies on atomic processes subject to the plasma environment including the α and β emissions and the ground state photoabsorption of the one- and two-electron atoms and ions. By carefully examining the spatial and temporal criteria of the Debye–Hückel (DH) approximation based on the classical Maxwell–Boltzmann statistics, we were able to represent the plasma effect with a Debye–Hückel screening potential VDH in terms of the Debye length D, which is linked to the ratio between the plasma density N and its temperature kT. Our theoretical data generated with VDH from the detailed non-relativistic and relativistic multiconfiguration atomic structure calculations compare well with the limited measured results from the most recent experiments. Starting from the quasi-hydrogenic picture, we were able to show qualitatively that the energy shifts of the emission lines could be expressed in terms of a general expression as a function of a modified parameter, i.e., the reduced Debye length λ. The close agreement between theory and experiment from our study may help to facilitate the plasma diagnostics to determine the electron density and the temperature of the outside plasma.

/pdf/atomic-processes-including-photoabsorption-subject-to-28p6bw63.pdf

Te-Kuei Fang

Papers

One- and two-photon ionization of hydrogen atom embedded in Debye plasmas

Quantum entanglement for helium atom in the Debye plasmas

Variation of the oscillator strengths for the α emission lines of the one- and two-electrons ions in dense plasma

Redshift of the isolated atomic emission line in dense plasma

Atomic Processes, Including Photoabsorption, Subject to Outside Charge-Neutral Plasma