Laser energy absorption coefficient and in-situ temperature measurement of laser-melted tungsten

Laser energy absorption coefficient and in-situ temperature measurement of laser-melted tungsten

•High-speed 2D temperature profiles were obtained for laser melted W spots.•Laser energy absorption coefficients above W melting point were measured.•Several observations indicated the W surface bubbling at ∼5000K in UHV. The energy absorption coefficient of tungsten surface (W) for 1064nm Nd:YAG la...

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Bibliographic Details
Published in:Fusion engineering and design Vol. 124; pp. 287 - 291
Main Authors: Maeji, T., Ibano, K., Yoshikawa, S., Inoue, D., Kuroyanagi, S., Mori, K., Hoashi, E., Yamanoi, K., Sarukura, N., Ueda, Y.
Format: Journal Article
Language:English
Published: Amsterdam Elsevier B.V 01-11-2017
Elsevier Science Ltd
Subjects:
Absorptivity
Adsorption
Bubbling
Color imagery
Contact melting
Dependence
Energy absorption
Energy absorption coefficient
Fusion
High speed cameras
High-speed 2D temperature measurement
Lasers
Melting points
Neodymium lasers
Nuclear reactors
Plasma
Semiconductor lasers
Spectral emissivity
Surface chemistry
Surface melting
Surface temperature
Temperature measurement
Temperature profiles
Tungsten
Tungsten (W)
Two dimensional analysis
YAG lasers
Surface melting
Tungsten (W)
Energy absorption coefficient
High-speed 2D temperature measurement
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Summary:•High-speed 2D temperature profiles were obtained for laser melted W spots.•Laser energy absorption coefficients above W melting point were measured.•Several observations indicated the W surface bubbling at ∼5000K in UHV. The energy absorption coefficient of tungsten surface (W) for 1064nm Nd:YAG laser was measured as a function of the induced energy. Result was confirmed by the reference spectral emissivity up to the melting point. Then, two non-contact surface temperature measurement diagnostics, a pyrometer measurement and a two-dimensional (2D) temperature measurement, were constructed for the laser-melted W spot. The 2D temperature profile was obtained by analyzing two-color images from a high-speed camera with an image splitter and a long-distance microscope. An OpenCV based program was developed for corrections on the tilted angle view and wavelength dependence of the captured intensities. W surface bubbling at the surface temperature near 5000K was indicated by high-speed camera images, unstable temperature developments, asymmetric temperature profiles, and the postmortem surface observations.
ISSN:0920-3796
1873-7196
DOI:10.1016/j.fusengdes.2017.04.025