Analytical formulae for the inverse bremsstrahlung absorption coefficient

Stallcop, James R.; Billman, K. W.

doi:10.1088/0032-1028/16/12/008

Cited by 38 publications

(7 citation statements)

References 5 publications

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“…Conversely, the plasma temperature rises at higher pressures, because of the strong laser absorption within the plasma explained by the inverse Bremsstrahlung (σ IB ∝ n e ) effect. 64,65 Above a certain pressure (for instance, 150 mbar), the plasma generation requires more laser energy to be imparted to the ionization. Therefore the portion of accessible laser energy for plasma Hashemi et al AIP Advances 4, 067121 (2014) heating is reduced, leading to a measurable temperature reduction.…”

Section: The Effect Of Chamber Pressurementioning

confidence: 99%

Characteristic emission enhancement in the atmosphere with Rn trace using metal assisted LIBS

Hashemi¹,

Parvin

Moosakhani

et al. 2014

AIP Advances

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Several characteristic emission lines from the metal targets (Cu, Zn and Pb) were investigated in trace presence of radon gas in the atmospheric air, using Q-SW Nd:YAG laser induced plasma inside a control chamber. The emission lines of metal species are noticeably enhanced in (Rn+air), relative to those in the synthetic air alone. Similar spectra were also taken in various sub-atmospheric environments in order to determine the optimum pressure for enhancement. Solid-state nuclear track detectors were also employed to count the tracks due to alpha particles for the activity assessment.

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Section: The Effect Of Chamber Pressurementioning

confidence: 99%

Characteristic emission enhancement in the atmosphere with Rn trace using metal assisted LIBS

Hashemi¹,

Parvin

Moosakhani

et al. 2014

AIP Advances

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“…• The f-f absorption is calculated using a generalization of the semi-classical Kramer's formula [13,[18][19][20][21][22] to account for multiply ionized ions and to include nonideality effects. Non-classical effects are taken into account through the use of the frequency-dependent Gaunt factor, G ff (ν, T ) (Karzas and Latter [23] and Stallcop and Billman [24]). • The normalized spectral line profile function, L( , ν) [13,[18][19][20][21][22][25][26][27][28][29][30], is calculated using the Voigt profile and atomic and spectroscopic terms/data from the National Institute of Standards and Technology (NIST) compilations that are based on the most accurate sources and calculations known at present [31].…”

Section: Radiation Transport and Opacity Calculationsmentioning

confidence: 99%

Improved modelling of electrothermal plasma source with radiation transport

Zaghloul¹

2008

J. Phys. D: Appl. Phys.

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An improved one-dimensional, time-dependent model with radiation transport is developed and used to simulate the evolution and flow of Ohmically heated nonideal plasma in the capillary of an electrothermal (ET) plasma source operated in the ablation stabilized arc regime. The model uses the Ohmic input power, recovered from the experimentally measured impedance, as the sole driving force of the computations to circumvent depending on arguable theoretical models of the resistivity of nonideal plasma. A consistent model of the equation of state and thermodynamic functions of weakly nonideal multi-component plasma mixtures is implemented and used to calculate the thermodynamic properties of the ET plasma generated from the ablation of the capillary wall. The flow velocity at the bore exit is not allowed to exceed the local sound speed and no prior assumptions of choked-flow are made at the bore exit. The frequency-dependent and frequency-averaged opacities of the plasma have been calculated considering the basic atomic processes of photoionization, inverse bremsstrahlung, resonant photoabsorption as well as electron scattering. Radiation transport has been implemented by modelling the plasma column as a grey gas the emissivity of which is calculated using an effective beam length Leb. The radiative heat flux escaping the surface of the grey plasma column is used to calculate the rate of the ablated mass improving the temporal behaviour of the calculated plasma parameters. Particular attention is devoted to investigating the ablation process and the evaluation of the so-called heat of ablation. Computational results are presented and discussed.

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“…Correction factor i G is known as the Gaunt factor [32,33]. The factor ( ) As before, the initial state is defined by its azimuthal quantum number l, the final state is defined by l′ , l max is the maximum of these two numbers, R is the corresponding matrix element.…”

Section: Opacitiesmentioning

confidence: 99%