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Akashev, L. A.; Кононенко, В. И.

doi:10.1023/a:1017502424054

Cited by 16 publications

(2 citation statements)

References 3 publications

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“…Similarly, our results for the reflectivity agree very well with the experimental measurement near 1 eV reported in [26] (the experimental point is shown with the error bar representing the dispersion over the experimental frequency range). By extending the previous Kohn-Sham calculations to higher temperature, we find a minimum in the electrical conductivities at about 6 eV, while the reflectivity coefficients show an exponential decrease with temperature.…”

Section: B Aluminumsupporting

confidence: 90%

Ionic and electronic transport properties in dense plasmas by orbital-free density functional theory

Sjostrom

Daligault

2015

Phys. Rev. E

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We validate the application of our recent orbital-free density functional theory (DFT) approach, [Phys. Rev. Lett. 113, 155006 (2014)], for the calculation of ionic and electronic transport properties of dense plasmas. To this end, we calculate the self-diffusion coefficient, the viscosity coefficient, the electrical and thermal conductivities, and the reflectivity coefficient of hydrogen and aluminum plasmas. Very good agreement is found with orbital-based Kohn-Sham DFT calculations at lower temperatures. Because the method does not scale with temperature, we can produce results at much higher temperatures than is accessible by the Kohn-Sham method. Our results for warm dense aluminum at solid density are inconsistent with the recent experimental results reported by Sperling et al. [Phys. Rev. Lett. 115, 115001 (2015)].

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Section: B Aluminumsupporting

confidence: 90%

Ionic and electronic transport properties in dense plasmas by orbital-free density functional theory

Sjostrom

Daligault

2015

Phys. Rev. E

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“…While temperature-dependent values for thermo-physical properties are available from commercial databases for pure metals, as well as alloys, there are no such ready-to-use data available in the literature or databases for the wavelength and temperature-dependent absorptivity A(λ, T). Thus, we conducted extensive literature research for the optical properties over a temperature range from room temperature to elevated temperatures at the molten state for copper [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33], aluminum [27][28][29][30][34][35][36][37][38][39][40][41][42][43][44][45][46] and iron [26][27][28][29][30][46][47][48][49][50][51][52]…”

Section: Evaluation Of the Optical And Thermo-physical Propertiesmentioning

confidence: 99%

Why Color Matters—Proposing a Quantitative Stability Criterion for Laser Beam Processing of Metals Based on Their Fundamental Optical Properties

Kohl

Kaufmann

Schmidt

2022

Metals

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With its excellent automation capability and localized energy input enabling precise, reproducible welds, laser beam welding represents a preferred industrial joining technology. Electro-mobility drastically increases the need for defect-free and automatable copper joining technologies. However, copper welds that are produced with state-of-the-art infrared lasers often suffer from spattering and porosity. Recent publications show distinct improvements using novel beam sources at visible wavelengths, attributing them to increased absorptivity. Nevertheless, this cannot fully explain the steadier process behavior. This wavelength-dependent process stability has not yet been investigated sufficiently. Therefore, we have developed a predictive material-dependent criterion indicating process stability based on the example of copper heat-conduction spot welding. For this purpose, we combined energy balances with thermo-physical material properties, taking into account the wavelength and temperature dependence of the optical properties. This paper presents the key mechanism that we identified as decisive for process stability. The criterion revealed that X-points (unique, material-specific wavelengths) represent critical stability indicators. Our calculations agree very well with experimental results on copper, steel and aluminum using two different wavelengths and demonstrate the decisive, material-dependent wavelength impact on process stability. This knowledge will help guide manufacturers and users to choose and develop beam sources that are tailored to the material being processed.

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A model of laser ablation with temperature-dependent material properties, vaporization, phase explosion and plasma shielding

2013

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Cited by 16 publications

References 3 publications

Ionic and electronic transport properties in dense plasmas by orbital-free density functional theory

Ionic and electronic transport properties in dense plasmas by orbital-free density functional theory

Why Color Matters—Proposing a Quantitative Stability Criterion for Laser Beam Processing of Metals Based on Their Fundamental Optical Properties

A model of laser ablation with temperature-dependent material properties, vaporization, phase explosion and plasma shielding

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