Pressure Ionization and Line Merging in Strongly Coupled Plasmas Produced by 100-fs Laser Pulses

Nantel, M.; Ma, Gengyu; Gu, S.; Côté, C. Y.; Itatani, J.; Umstadter, D.

doi:10.1103/physrevlett.80.4442

Cited by 143 publications

(110 citation statements)

References 27 publications

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“…In table 10, we have displayed the comparison of present results for transition energies of C 4+ , Al 11+ and Ar 16+ with experimental measurements [22][23][24] and existing theoretical calculations [36]. Table-10 clearly depicts that the present results are in good agreement with the experimental measurements as compared to other theoretical results.…”

supporting

confidence: 77%

Nonrelativistic structure calculations of two-electron ions in a strongly coupled plasma environment

Bhattacharyya¹,

Saha

Mukherjee³

2015

Phys. Rev. A

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In this work, the controversy between the interpretations of recent measurements on dense aluminum plasma created with Linac coherent light sources (LCLS) X-ray free electron laser (FEL) and Orion laser has been addressed. In both kind of experiments, helium-like and hydrogen-like spectral lines are used for plasma diagnostics . However, there exist no precise theoretical calculations for He-like ions within dense plasma environment. The strong need for an accurate theoretical estimates for spectral properties of He-like ions in strongly coupled plasma environment leads us to perform ab initio calculations in the framework of Rayleigh-Ritz variation principle in Hylleraas coordinates where ion-sphere potential is used. An approach to resolve the long-drawn problem of numerical instability for evaluating two-electron integrals with extended basis inside a finite domain is presented here. The present values of electron densities corresponding to disappearance of different spectral lines obtained within the framework of ion-sphere potential show excellent agreement with Orion laser experiments in Al plasma and with recent theories. Moreover, this method is extended to predict the critical plasma densities at which the spectral lines of H-like and He-like carbon and argon ions disappear. Incidental degeneracy and level-crossing phenomena are being reported for the first time for two-electron ions embedded in strongly coupled plasma. Thermodynamic pressure experienced by the ions in their respective ground states inside the ion-spheres are also reported.

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supporting

confidence: 77%

Nonrelativistic structure calculations of two-electron ions in a strongly coupled plasma environment

Bhattacharyya¹,

Saha

Mukherjee³

2015

Phys. Rev. A

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“…Very recently, Shuji et al [29] have calculated the radiative opacity of the Al plasma in LTE by using the time-dependent density-functional theory (TDDFT) at temperature T = 20 eV and density 0.01 g/cm 3 . The strongly coupled plasma is mostly seen in the highly evolved stars, interior of the Jovian planets, explosive shock tubes, laser produced plasma and inertial confinement fusion plasmas [4,[30][31][32]. Most of these studies have been carried out in the Debye model formalism.…”

Section: Introductionmentioning

confidence: 99%

Plasma screening effects on the electronic structure of multiply charged Al ions using Debye and ion-sphere models

2016

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We analyze atomic structures of plasma embedded aluminum (Al) atom and its ions in the weakly and strongly coupling regimes. The plasma screening effects in these atomic systems are accounted for using the Debye and ion sphere (IS) potentials for the weakly coupling and strongly coupling plasmas, respectively. Within the Debye model, special attention is given to investigate the spherical and non-spherical plasma-screening effects considering in the electron-electron interaction potential. The relativistic coupled-cluster (RCC) method has been employed to describe the relativistic and electronic correlation effects in the above atomic systems. The variation in the ionization potentials (IPs) and excitation energies (EEs) of the plasma embedded Al ions are presented. It is found that the atomic systems exhibit more stability when the exact screening effects are taken into account. It is also showed that in the presence of strongly coupled plasma environment, the highly ionized Al ions show blue and red shifts in the spectral lines of the transitions between the states with same and different principal quantum numbers, respectively. Comparison among the results obtained from the Debye and IS models are also carried out considering similar plasma conditions.

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“…Strong coupling is observed in dense astrophysical environments [1], such as the interiors of gas giant planets, and in laser-cooled ions [2], dusty plasmas [3], and solid targets [4] and clusters [5] irradiated by pulsed high-intensity lasers. Equilibration in these systems is of particular interest because it involves the establishment of spatial correlations between particles.…”

mentioning

confidence: 99%

Electron Screening and Kinetic-Energy Oscillations in a Strongly Coupled Plasma

et al. 2004

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We study equilibration of strongly coupled ions in an ultracold neutral plasma produced by photoionizing laser-cooled and trapped atoms. By varying the electron temperature, we show that electron screening modifies the equilibrium ion temperature. Even with few electrons in a Debye sphere, the screening is well described by a model using a Yukawa ion-ion potential. We also observe damped oscillations of the ion kinetic energy that are a unique feature of equilibration of a strongly coupled plasma. DOI: 10.1103 There has been significant theoretical study of the equilibration of strongly coupled plasmas [6 -12], especially in the context of plasmas produced with high-intensity lasers. In addition to generating fundamental interest, this problem challenges computational resources and techniques. Experimental results have been lacking, however, because of the fast time scales involved and limited diagnostics.Ultracold neutral plasmas [13], produced by photoionizing clouds of laser-cooled and trapped atoms, are ideal for experimental studies. The equilibration of the plasma is relatively slow ( 100 ns) due to lower plasma density. Ultracold neutral plasmas also offer a high level of control and diagnostics. By varying laser intensities and wavelengths, it is possible to accurately set the initial density and energy of the system. Optical imaging [14] provides an in situ probe of plasma properties with excellent spatial, temporal, and spectral resolution.In this Letter, we explore ion equilibration during the first microsecond after the plasma is created. The density sets the time and the energy scale for equilibration, but electron screening effects are evident. Even when the number of electrons per Debye sphere is small, the equilibration temperature of the ions agrees with a model [15] that uses a Yukawa ion-ion potential.We also observed oscillations of the ion kinetic energy. For many years, this phenomenon has been the subject of intense study through analytic calculations [7] and simulations [6,[8][9][10][11][12]] of one-component strongly coupled plasmas, but it has not previously been observed experimentally. The oscillations and their damping reflect universal dynamics of a Coulomb system with spatial correlations.Details on laser cooling, plasma formation, and imaging are given in [14,16]. The experiment starts with strontium atoms that are cooled and trapped in a magneto-optical trap (MOT). The neutral atom cloud is characterized by a temperature of about 10 mK, 2 10 8 atoms, and a Gaussian density distribution. We vary the atom density by changing the MOT parameters, or by turning the MOT off and releasing the atoms in a ballistic expansion. Up to 30% of the neutral atoms are then ionized with one photon from the cooling laser and one photon from a pulsed dye laser. The ion density distribution equals the atom distribution at the time of photoionization and is given by n i r n 0i exp ÿr 2 =2 2 , with from 0.6 to 1 mm and n 0i from 2 10 9 to 1:4 10 10 cm ÿ3 . The electron density, n e r , closely follows ...

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Pressure Ionization and Line Merging in Strongly Coupled Plasmas Produced by 100-fs Laser Pulses

Cited by 143 publications

References 27 publications

Nonrelativistic structure calculations of two-electron ions in a strongly coupled plasma environment

Nonrelativistic structure calculations of two-electron ions in a strongly coupled plasma environment

Plasma screening effects on the electronic structure of multiply charged Al ions using Debye and ion-sphere models

Electron Screening and Kinetic-Energy Oscillations in a Strongly Coupled Plasma

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