Model of the DAC assembly used in the FE calculations.
Finite-element calculations of the temperature profiles in the axial direction of the DAC cavity in the center of a laser-heating spot for the case of the symmetric double-sided heating. (a) Comparison of the temperature profiles corresponding to the time when the maximum of temperature is reached at the coupler–medium interface for continuous, 2 μs pulsed, and 10 ns pulsed laser heating regimes. (b) Evolution of the temperature profile with time for 10 ns pulsed laser heating; the maximum of the laser intensity (shown in (a)) corresponds to the 20 ns time. Thin vertical lines correspond to the coupler-medium interface. The medium–diamond interfaces correspond to ±8 μm abscisses.
Finite element simulation of the coupler surface temperature history. (a)–(c) are corresponding to 2 μs, 10 ns, CW laser heating, respectively. The dashed curve corresponds to calculations using conductive transfer only while the solid curve corresponds to calculations run with both conductive and radiative transfers. For panels (a) and (b), these curves are indistinguishable for the scale they are presented. The difference between these two curves is shown in gray (referred to right ordinates). Insets show the external power time profile applied to the system.
Finite element simulation of the Fe sample surface temperature history for the pulsed heating experiment of Ref. 17 for different values of the peak laser power. The case of the symmetric double-sided heating is examined. Panels (a) and (b) correspond to the cases of constant emissivity and step-like emissivity decrease through the melting transition, respectively.
Comparison of the experimentally determined peak surface temperature of the Fe sample 17 with the calculated results from finite element simulations for different peak laser powers.
Finite element calculations for the surface temperature history of a Pt laser light absorber in H2 medium for different peak laser powers. The case of the symmetric double-sided heating is examined. The geometrical parameters and laser pulse parameters are from the experimental work of Ref. 34 . The constant thermal conductivity and that increased by a factor of 10 at the melt line refer to the temperature dependence of this quantity for hydrogen, which was assumed in the calculations.
Finite element calculations of the surface temperature of the Pt laser light absorber as a function of the peak laser power. The constant thermal conductivity and that increased by a factor of 10 at the melt line refer to the temperature dependence of this quantity for hydrogen, which was assumed in the calculations.
Finite element calculations of the surface temperature histories (T1 and T2 correspond to different sides of the sample) of a plate-like sample heated from one side (side 1) with a laser having a wave function time profile. The amplitude of the laser power modulation was 10% of the total applied laser power. The laser power was ramped up as shown in the inset to Fig. 3(c) . The results shown correspond to periods of time when the steady state is reached. The straight lines with the arrow illustrate the phase shift between the surface temperatures. Left and right panels correspond to two different values of the thermal conductivity of the sample.
Finite element calculations of the phase shift (left panel) and amplitude ratios (right panel) of the surface temperatures of a plate-like sample heated from one side with a laser having a wave function time profile. The results are presented as a function of the dimensionless parameter u. The solid lines are guides to the eye for the calculations performed for the medium (Ar) with thermal conductivity Kmedium(300 K) = 10 W/(m × K). The gray thick lines correspond to the results (Kelvin functions) for the classic Ångström method (for a cylindrical sample).
Thermochemical parameters of materials used in model FE calculations (Fig. 2 ).
Laser intensity parameters needed for heating of a sample surface to a peak temperature of 4000 K (one side) in FE calculations (Fig. 2 ).
Thermochemical parameters of materials used in FE calculations of the melting behavior of Fe in N2 medium at 18.8 GPa (Fig. 4 ).
Thermochemical parameters of materials used in FE calculations of the melting behavior of hydrogen (using a Pt laser light absorber) at 75 GPa (Fig. 6 ).
Thermochemical parameters of materials used in FE calculations of the time-dependent temperature map in the DAC cavity, which occurs in response to a single-sided laser heating with a wave function time profile.
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