Containerless Study of Metal Evaporation by Laser Induced Fluorescence

1986 ◽  
Vol 87 ◽  
Author(s):  
Robert A. Sghiffman ◽  
Paul C. Nordine
Keyword(s):  
Laser Heating ◽  
Electronic States ◽  
Laser Induced Fluorescence ◽  
Temperature Data ◽  
Radiative Heating ◽  
Atomic Vapors ◽  
Metal Evaporation ◽  
Tungsten Filaments ◽  
Laser Heated ◽  
Electromagnetically Levitated

AbstractLaser induced fluorescence (LIF) detection of atomic vapors was used to study evaporation from electromagnetically levitated and CW CO2 laser heated molydenum spheres and resistively heated tungsten filaments. Electromagnetic (EM) levitation in combination with laser heating of tungsten, zirconium, and aluminum specimens was also investigated. LIF intensity vs temperature data were obtained for molybdenum ( 7S3 ) atoms and six electronic states of atomic tungsten, at temperatures up to the melting point of each metal. The detected fraction of the emitted radiation was reduced by self-absorption effects at the higher experimental temperatures.Vaporization enthalpies derived from data for which less than half the LIF intensity was self-absorbed were ΔHo0 = -636 ± 24 kJ/g-mol for Mo and 831 ± 32 kJ/g-mol for W. Space-based applications of EM levitation in combination with radiative heating are discussed.

scholarly journals Spheroidization of Nickel Powder and Coating with Carbon Layer through Laser Heating

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1641 ◽  
Author(s):  
Shuang Li ◽  
Yu-Ling Shao ◽  
Lan Cui ◽  
Sergei Kulinich ◽  
Xi-Wen Du
Keyword(s):  
Laser Heating ◽  
Nickel Powder ◽  
Carbon Layer ◽  
Liquid Droplets ◽  
Pure Ethanol ◽  
Precipitation Mechanism ◽  
Excess Carbon ◽  
Lower Solubility ◽  
Long Pulse ◽  
Laser Heated

We developed a simple and efficient process, laser heating of nickel powder in ethanol, to produce carbon-encapsulated nickel microspheres. Long-pulse-width laser heated nickel powder suspended in pure ethanol into liquid droplets. In turn, the latter droplets became sphere-like, pyrolyzed surrounding ethanol and dissolved the produced carbon atoms. Because of their lower solubility in solid nickel, excess carbon atoms were then expelled from the metal core after solidification, thus forming graphite-like shells on the laser-modified Ni spheres. Hence, after pyrolysis the transformation of carbon was found to follow the dissolution-precipitation mechanism. The produced carbon-encapsulated nickel microspheres exhibited higher oxidation resistance compared with the initial nickel powder, while keeping their magnetic properties essentially unchanged.

Boubaker Polynomials Expansion Scheme Solution to the Heat Transfer Equation Inside Laser Heated Biological Tissues

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
M. A. Aweda ◽  
M. Agida ◽  
M. Dada ◽  
O. B. Awojoyogbe ◽  
K. Isah ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Analytical Solution ◽  
Numerical Simulations ◽  
Laser Heating ◽  
Transfer Equation ◽  
Biological Tissues ◽  
Heat Transfer Equation ◽  
Boubaker Polynomials ◽  
Laser Heated ◽  
Expansion Scheme

In this study, an analytical solution to the heat transfer equation in biological tissues during laser heating is presented. The results were compared to recently published numerical simulations.

Laser-induced fluorescence and discharge emission spectra of CrO. Rotational analysis of the A5Π–X5Π transition

1980 ◽  
Vol 58 (4) ◽  
pp. 516-533 ◽  
Author(s):  
W. H. Hocking ◽  
A. J. Merer ◽  
D. J. Milton ◽  
W. E. Jones ◽  
G. Krishnamurty
Keyword(s):  
Fluorescence Spectra ◽  
Rotational Temperature ◽  
Electronic States ◽  
Emission Spectra ◽  
Laser Induced Fluorescence ◽  
Spin Orbit Coupling ◽  
Excitation Spectra ◽  
Large Numbers ◽  
Parallel Polarization ◽  
Indirect Information

The A5Π–X5Π electronic transition of CrO, near 6000 Å, has been analysed in detail using laser-induced fluorescence and conventional discharge emission spectroscopy. The transition provides the first instance where it has been possible to analyse the rotational structures of quintet electronic states completely. Although the parallel polarization of the transition has prevented the spin–orbit coupling and Λ-doubling intervals from being observed directly, it is shown that sufficient indirect information exists in the spectrum for them to be obtained with fair precision. The excited state, A5Π, is perturbed by large numbers of other electronic states which have no intensity of their own for emission to the ground state. The analysis of the perturbed regions has been greatly facilitated by the laser-induced fluorescence spectra: the excitation spectra correspond to a rotational temperature close to room temperature (which offers a significant improvement in resolution over the discharge spectra), and the J-assignments of the perturbed lines given by the resolved fluorescence spectra are unambigious

scholarly journals A portable on-axis laser-heating system for near-90° X-ray spectroscopy: application to ferropericlase and iron silicide

2020 ◽  
Vol 27 (2) ◽  
pp. 414-424 ◽  
Author(s):  
Georg Spiekermann ◽  
Ilya Kupenko ◽  
Sylvain Petitgirard ◽  
Manuel Harder ◽  
Alexander Nyrow ◽  
...  
Keyword(s):  
Laser Heating ◽  
Iron Silicide ◽  
Heating System ◽  
Laser Source ◽  
Nuclear Inelastic Scattering ◽  
X Rays ◽  
X Ray ◽  
Signal Collection ◽  
Diamond Anvil ◽  
Laser Heated

A portable IR fiber laser-heating system, optimized for X-ray emission spectroscopy (XES) and nuclear inelastic scattering (NIS) spectroscopy with signal collection through the radial opening of diamond anvil cells near 90°with respect to the incident X-ray beam, is presented. The system offers double-sided on-axis heating by a single laser source and zero attenuation of incoming X-rays other than by the high-pressure environment. A description of the system, which has been tested for pressures above 100 GPa and temperatures up to 3000 K, is given. The XES spectra of laser-heated Mg0.67Fe0.33O demonstrate the potential to map the iron spin state in the pressure–temperature range of the Earth's lower mantle, and the NIS spectra of laser-heated FeSi give access to the sound velocity of this candidate of a phase inside the Earth's core. This portable system represents one of the few bridges across the gap between laser heating and high-resolution X-ray spectroscopies with signal collection near 90°.

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