Temperature distributions in the laser-heated diamond anvil cell from 3-D numerical modeling

Abstract

The effect of sample thickness and insulation layers on the temperature distribution in the laser-heated diamond cell Rev. Sci. Instrum. 72, 1306 10.1063/1.1343863 Temperature and pressure distribution in the laser-heated diamond-anvil cell Rev. Sci. Instrum. 69, 2421 (1998); 10.1063/1.1148970Numerical calculations of the temperature distribution and the cooling speed in the laser-heated diamond anvil cellWe present TempDAC, a 3-D numerical model for calculating the steady-state temperature distribution for continuous wave laser-heated experiments in the diamond anvil cell. TempDAC solves the steady heat conduction equation in three dimensions over the sample chamber, gasket, and diamond anvils and includes material-, temperature-, and direction-dependent thermal conductivity, while allowing for flexible sample geometries, laser beam intensity profile, and laser absorption properties. The model has been validated against an axisymmetric analytic solution for the temperature distribution within a laser-heated sample. Example calculations illustrate the importance of considering heat flow in three dimensions for the laser-heated diamond anvil cell. In particular, we show that a "flat top" input laser beam profile does not lead to a more uniform temperature distribution or flatter temperature gradients than a wide Gaussian laser beam. V C 2013 AIP Publishing LLC. [http://dx.

Measurements of thermal conductivity across the B1-B2 phase transition in NaCl

“…Our approach combines experimental laser-heated DAC methods with a 3-D numerical heat flow model of the sample and cell components to interpret the measurements. 18 In the experiment, a sample consisting of a salt medium surrounding a transition metal infrared laser-absorber is loaded into a gasketed sample chamber in the DAC. The sample is heated from one side using an infrared laser.…”

Radiometric Temperature Measurements in Nongray Ferropericlase With Pressure‐ Spin‐ and Temperature‐Dependent Optical Properties

“…Flat, single-crystalline ferropericlase (thickness 2z) is placed in the center of the DAC gasket cavity (thickness 2d) and surrounded by nonabsorbing pressure medium that also provides thermal insulation ( Figure 1). Double-sided near-IR laser heating produces steep symmetric temperature profiles across the sample due to the very high thermal conductivity of the diamond anvils, which remain essentially at 300 K (Bodea & Jeanloz, 1989;Kiefer & Duffy, 2005;Petitgirard et al, 2014;Rainey et al, 2013). The shape of the temperature profile is most sensitive to the absorption coefficient at the heating wavelength, the presence of thermal insulator/pressure medium, its thickness, and the sample to insulation thermal conductivity ratio (Kiefer & Duffy, 2005;Montoya & Goncharov, 2012).…”

Thermal Equation of State of Fe3C to 327 GPa and Carbon in the Core

“…The experimental pressures were determined using the EOS of KBr (B2) [22] and that of MgO [23] for the high-pressure and high-temperature experiments, whereas the compression curve of pyrite SiO 2 at 300 K was used for determination of pressure for the experiments exceeding 298.9 GPa [27]. The temperature distribution in the pressure medium in the double-heated diamond anvil cell (DAC) was evaluated from 3-dimensional numerical modeling [28]. This model calculation indicates that with a thickness of 1-2 µm, the temperature difference between the inner and anvil surfaces in the MgO layer is around 100-200 K at 2000 K, which is equivalent to the temperature uncertainty in the present experiment.…”