Normal spectral emissivity measurement of molten copper using an electromagnetic levitator superimposed with a static magnetic field

Abstract

The normal spectral emissivity of molten copper was determined in the wavelength range of 780–920 nm and in the temperature range of 1288–1678 K, by directly measuring the radiance emitted by an electromagnetically levitated molten copper droplet under a static magnetic field of 1.5 T. The spectrometer for radiance measurement was calibrated using the relation between the theoretical blackbody radiance from Planck's law and the light intensity of a quasi-blackbody radiation source measured using a spectrometer at a given temperature. As a result, the normal spectral emissivity of molten copper was determined as 0.075 ± 0.011 at a wavelength of 807 nm, and it was found that its temperature dependence is negligible in the entire measurement temperature range tested. In addition, the results of the normal spectral emissivity and its wavelength dependence were discussed, in comparison with those obtained using the Drude free-electron model.

Interaction of a Low-Power Laser Radiation with Nanoparticles Formed over the Copper Melt in Rarefied Argon Atmosphere

“…The spectral optical constants of copper have been studied in detail for solid copper [33,34]. Note that the measurements reported in References [35][36][37] showed a considerable increase in normal emittance of copper at the melting, but there is no detailed spectral data for optical properties of molten copper in the visible range [38]. Therefore, we used a linear interpolation of tabulated optical constants of solid copper reported in Reference [33] with the resulting values of indices of refraction and absorption n = 0.128 and κ = 3.754 at λ = 660 nm.…”

Development of Heat-of-fusion Measurement for Metals Using a Closed-type Aerodynamic Levitator

“…To prevent contamination from the contact materials, containerless processing for the measurement of thermophysical properties using levitation has been developed. The thermophysical properties of metallic liquids and liquid alloys, such as surface tension (3)(4)(5)(6)(7)(8), density (9)(10)(11)(12), viscosity (7,8,13) heat capacity (14), thermal conductivity (14,15), and normal spectral emissivity (16)(17)(18), have been measured using electromagnetic levitation or electrostatic levitation.…”

Measurements of the directional spectral emissivity based on a radiation heating source with alternating spectral distributions

“…Many measurement methods have been developed to measure the spectral emissivity of materials at various temperatures and spectral ranges. The direct measurement method of the spectral emissivity was widely used that compare the sample spectral intensity to the blackbody spectral intensity at the same temperature [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. For example, Rozenbaum et al [4] used a spectroscopic method to measure the directional spectral emissivity of semi-transparent materials for wavelengths of 10-12000 cm À1 and temperatures of 600-3000 K with the sample heated by a carbon dioxide laser.…”