Emission from weakly nonideal helium plasmas produced in flash lamps

The electric microfield distribution at charged particles is studied for two-component electron-ion plasmas using molecular dynamics simulation and theoretical models. The particles are treated within classical statistical mechanics using an electron-ion Coulomb potential regularized at distances less than the de Broglie length to take into account the quantum-diffraction effects. The potential-of-mean-force (PMF) approximation is deduced from a canonical ensemble formulation. The resulting probability density of the electric microfield satisfies exactly the second-moment sum rule without the use of adjustable parameters. The correlation functions between the charged radiator and the plasma ions and electrons are calculated using molecular dynamics simulations and the hypernetted-chain approximation for a two-component plasma. It is shown that the agreement between the theoretical models for the microfield distributions and the simulations is quite good in general.

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“…where ∇ 0 is the gradient with respect to r 0 and the average is over the canonical ensemble defined in Eq. (5).…”

Section: Second Momentmentioning

confidence: 99%

Microfield distributions in strongly coupled two-component plasmas

2005

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“…They describe also the reduction of the statistical weight of electron levels which in turn affects the populations of excited states. The latter effect leads to an effective cut-off for the partition functions and determines the behavior of optical properties of plasmas by increasing the densities of charged particles [15,29,30]. Also, a careful approximation of the Planck-Larkin partition function in the chemical picture has been put forward to address the dissolution of bound states [31].…”

Section: Radiative Transfer and Self-absorptionmentioning

confidence: 99%

“…The quasi-static microfield distribution function at neutral atom is taken according to Hooper [33]. The energy levels of the bound states can be perturbed by the microfield strength and the higher series of transition will disappear, when the microfield strength approach β c , in which the discrete upper levels of the permitted transitions are dissolved above the threshold [29,34]. The Balmer background continuum is calculated from Coulomb form of the absorption coefficient corresponding to the photoionization cross-section σ(ω) [15,26]…”

Section: Radiative Transfer and Self-absorptionmentioning

confidence: 99%

Diagnostics of High‐Pressure Arc Plasmas by Hydrogen Balmer Spectra

Omar

Wierling

Röpke

2011

Contrib. Plasma Phys.

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We re-examine several Balmer spectra obtained from high-pressure arc discharges (Radtke and Günther, Contrib. Plasma Phys. 26, 143 (1986); Radtke, Günther, and Spanke, ibid. 26, 151 (1986)). By matching synthetic spectra to the experimental line profiles, we infer plasma parameters such as density, temperature, and composition. Spectral line modeling is based on a microscopic quantum statistical approach. Corrections accounting to the merging lines near the threshold are describe following a model of D'yachkov. Self-absorption is clearly visible in the spectra and accounted for in one-dimensional model assuming thermal equilibrium. A consistency check is performed by comparing to the broadening of silicon impurity lines, where present in some of the spectra. Furthermore, a comparison is made with predictions from a fluid variational model for the composition and the equation of state of the plasma.

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“…They describe also the reduction of the statistical weight of electron levels which in turn affects the populations of excited states. The latter effect leads to an effective cut-off for the partition functions and determines the behavior of optical properties of plasmas by increasing the densities of charged particles [10,15,16]. Also, a careful approximation of the Planck-Larkin partition function in the chemical picture has been put forward to address the dissolution of bound states [17].…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Balmer Spectrum from a High‐Pressure Arc Discharge: Revisited

Omar

Wierling

Günter

et al. 2007

Contrib. Plasma Phys.

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The interpretation of hydrogen Balmer spectra emitted from a high-pressure arc discharge (Radtke and Günther, Contrib. Plasma Phys. 26, 143 (1986)) is re-examined. Assuming local thermodynamic equilibrium, synthetic Balmer spectra are calculated for given temperature and density conditions. Radiation transport is accounted for using a one-dimensional plasma layer model. The lineshape of bound-bound transitions is determined using a microscopic quantum-statistical approach. Free-free and free-bound contributions are added by taking expressions from literature. Comparing the synthetic spectra with experimental ones, plasma temperature and density conditions are inferred. The plasma parameters are confronted with theoretical results for the compositions of dense plasma.

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Emission from weakly nonideal helium plasmas produced in flash lamps

Cited by 13 publications

References 25 publications

Microfield distributions in strongly coupled two-component plasmas

Microfield distributions in strongly coupled two-component plasmas

Diagnostics of High‐Pressure Arc Plasmas by Hydrogen Balmer Spectra

Hydrogen Balmer Spectrum from a High‐Pressure Arc Discharge: Revisited

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