Normal Spectral Emissivity Measurement of Molten Cu–Co Alloy Using an Electromagnetic Levitator Superimposed with a Static Magnetic Field

  • Shoya Ueno
  • Yuki Nakamura
  • Ken-Ichi Sugioka
  • Masaki Kubo
  • Takao TsukadaEmail author
  • Masahito Uchikoshi
  • Hiroyuki Fukuyama


The normal spectral emissivity of molten Cu–Co alloy with different compositions was measured in the wavelength range of 780 nm to 920 nm and in the temperature range of 1430 K to 1770 K including the undercooled condition by an electromagnetic levitator superimposed with a static magnetic field. The emissivity was determined as the ratio of the radiance from a levitated molten Cu–Co droplet measured by a spectrometer to the radiance from a blackbody calculated by Planck’s law at a given temperature, where a static magnetic field of 2.5 T to 4.5 T was applied to the levitated droplet to suppress the surface oscillation and translational motion of the sample. We found little temperature dependence of the normal spectral emissivity of molten Cu–Co alloy. Concerning the composition dependence, the emissivity decreased markedly above 80 at%Cu and reached that of pure Cu, although its dependence was low between 20 at%Cu and 80 at%Cu. In addition, this composition dependence of the emissivity of molten Cu–Co alloy can be explained well by the Drude free-electron model.


Composition dependence Drude model Electromagnetic levitation Molten Cu–Co alloy Normal spectral emissivity Static magnetic field 

List of Symbols


Elementary electric charge (C)


Extinction coefficient (–)


Rest mass of an electron (kg)


Number of free electrons per unit volume (\(\hbox {m}^{-3}\))


Refractive index (–)

Greek Letters

\(\varepsilon \)

Emissivity (–)

\(\varepsilon _r, \varepsilon _i\)

Real and imaginary parts of the complex dielectric constant (–)

\(\varepsilon _0\)

Permittivity of vacuum (\(\hbox {F} {\cdot } \hbox {m}^{-1}\))

\(\rho _{el}\)

Electrical resistivity (\(\Omega ^{-1} {\cdot } \hbox {m}^{-1}\))

\(\sigma \)

Uncertainty (–)

\(\tau \)

Relaxation time of free electrons (s)

\(\omega \)

Angular frequency of the electric field (\(\hbox {rad} {\cdot } \hbox {s}^{-1}\))

\(\omega _p\)

Plasma frequency (\(\hbox {rad} {\cdot } \hbox {s}^{-1}\))



This study was supported by JSPS KAKENHI Grant No. 25289273.


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Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  1. 1.Department of Chemical EngineeringTohoku UniversitySendai-shiJapan
  2. 2.Department of Mechanical Systems EngineeringToyama Prefectural UniversityImizu-shiJapan
  3. 3.Institute of Multidisciplinary Research for Advanced MaterialsTohoku UniversitySendai-shiJapan

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