Thermal Conductivities of Tungsten and Molybdenum at Incandescent Temperatures

Osborn, Robert H.

doi:10.1364/josa.31.000428

Cited by 31 publications

(5 citation statements)

References 6 publications

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“…3. The shallow minimum in the thermal conductivity is located close to 2000 K. Experiments at ambient pressure [12][13][14][15][16][17] showed that the thermal conductivity decreases with the temperature up to the melting temperature. This decrease is pronounced below 1000 K 14 but weakens at higher temperature.…”

Section: B Thermal Conductivitymentioning

confidence: 91%

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Thermoelectric transport properties of molybdenum fromabinitiosimulations

French

Mattsson

2014

Phys. Rev. B

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We employ ab initio simulations based on density functional theory (DFT) to calculate the electronic transport coefficients (electrical conductivity, thermal conductivity, and thermopower) of molybdenum over a broad range of thermodynamic states. By comparing to available experimental data, we show that DFT is able to describe the desired transport properties of this refractory metal with high accuracy. Most noteworthy, both the positive sign and the quantitative values of the thermopower of solid molybdenum are reproduced very well. We calculate the electrical and thermal conductivity in the solid and the fluid phase between 1000 K and 20 000 K and a wide span in density and develop empirical fit formulae for direct use in practical applications, such as magnetohydrodynamics simulations. The influence of thermal expansion in conductivity measurements at constant pressure is also discussed in some detail.

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Section: B Thermal Conductivitymentioning

confidence: 91%

“…The thermal conductivity, λ, of solid molybdenum was probed experimentally up to melting. [12][13][14][15][16][17][18] In the liquid it is typically approximated from the electrical conductivity using the WiedemannFranz law.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric transport properties of molybdenum fromabinitiosimulations

French

Mattsson

2014

Phys. Rev. B

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“…This estimation gives an upper bound on the radiative heat transfer from the plasma, as plasmas in hypersonic flights are optically thin and have much lower radiation fluxes. Q cond = −k W dT/dx is the conductive cooling flux, which is assumed to be negligible due to the low thermal conductivity of tungsten at high temperatures [23].…”

Section: Heat Transfer Processes At the Leading Edge Surface Of The H...mentioning

confidence: 99%

Cesium seeding for effective electron transpiration cooling in hypersonic flows

Sahu

Tropina

Andrienko

et al. 2022

Plasma Sources Sci. Technol.

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The concept of electron transpiration cooling (ETC) uses thermionic emission of electrons from a low work function material to cool surfaces in hypersonic ﬂight. A theoretical estimate of the emission current is given by the Richardson-Dushman equation. In hypersonic ﬂights, the emission current can deviate from this estimate as the ambient air is partially ionized and a plasma sheath forms near the surface. Depending on the sheath structure, the emission current can be enhanced by the Schottky eﬀect, or could be reduced by the space charge eﬀects. In this study, we present a theoretical analysis of electron transpiration cooling of the leading-edge surface of a hypersonic vehicle, considering the transpiration of liquid cesium through a porous tungsten material. A part of the transpired cesium is adsorbed on the surface, which lowers the emitter work function, while the rest is evaporated due to high surface temperatures. Both the eﬀects provide substantial cooling. The evaporated cesium is ionized in the ambient air, which alters the plasma conductivity and reduces space charge eﬀects. The eﬀect of individual ﬁelds of ionized species near the surface is found to be negligible. Cesium transpiration is found to eliminate the requirement for an applied surface bias and enable stable operation at surface temperatures below 2000 K.

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“…The refractory metals of the sixth column of the periodic classification of elements, chromium (Cr), molybdenum (Mo) and rungsten (W) are of considerable practical interest for applications exploiting their outstanding properties including high melting temperatures [1], low thermal expansion [2][3][4], high thermal conductivity [5][6][7] and mechanical resistance [8][9][10]. Cr is used to harden steel, to manufacture stainless steel and as catalytic material [11], Mo is used in steel alloys to increase hardness, electrical conductivity and resistance to corrosion and wear [12] whereas W is used in heating elements, in superalloys to form wear resistant coatings and in fusion reactors as plasma facing material capable to sustain the high heat loads [13,14].…”

Section: Introductionmentioning

confidence: 99%

Phenomenological potentials for the refractory metals Cr, Mo and W

Baldinozzi¹,

Pontikis²

2022

J. Phys.: Condens. Matter

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Cohesion in the refractory metals Cr, Mo, and W is phenomenologically described in this work via a n-body energy functional with a set of physically motivated parameters that were optimized to reproduce selected experimental properties characteristic of perfect and defective crystals. The functional contains four terms accounting for the hard-core repulsion, the Thomas-Fermi kinetic energy repulsion and for contributions to the binding energy of s and d valence electrons. Lattice dynamics, molecular statics, and molecular dynamics calculations show that this model describes satisfactorily thermodynamic properties of the studied metals whereas, unlike other empirical approaches from the literature, predictions of phonon dispersion relations and of surface and point defect energetics reveal in fair good agreement with experiments. These results suggest that the present model is well adapted to large-scale simulations and whenever total energy calculations of thermodynamic properties are unfeasible.

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Thermal Conductivities of Tungsten and Molybdenum at Incandescent Temperatures

Cited by 31 publications

References 6 publications

Thermoelectric transport properties of molybdenum fromabinitiosimulations

Thermoelectric transport properties of molybdenum fromabinitiosimulations

Cesium seeding for effective electron transpiration cooling in hypersonic flows

Phenomenological potentials for the refractory metals Cr, Mo and W

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