HR: 0830h
AN: V31D-0968    [PDF]
TI: Finite-Element Modeling of the Thermal Structure in Laser-Heated Diamond Anvil Cell Experiments
AU: * Kiefer, B
EM: bkiefer@nmsu.edu
AF: Physics Department New Mexico State University, PO 30001; MSC 3D, Las Cruces, NM 88003-8001 United States
AU: Duffy, T S
EM: duffy@princeton.edu
AF: Department of Geosciences Princeton University, 114 Guyot Hall, Princeton, NJ 08544 United States
AB: Laser-heated diamond anvil cell experiments (LHDAC) form an integral part of the exploration of the physical properties of planetary materials at pressures and temperatures characteristic of planetary interiors. While it is possible to measure the radial temperature distribution in LHDAC experiments it is far more difficult to study the axial temperature gradient in these experiments. However, experimental observations are commonly made along the DAC axis and the observed signal represents a volume average of the thermal structure along the DAC axis. It is therefore important to analyze the effect of different sample assemblages and different insulating materials on the axial temperature gradient. In order to address these issues we have performed finite element simulations for different geometries and insulating media. All calculations were performed in (2d) cylindrical geometry with dynamic grid refinement. Our steady-state calculations confirm previous studies in that the diamond anvils remain essentially at room temperature, regardless of the insulating medium. Furthermore we identify the thermal conductivity contrast of sample and insulating medium as a key parameter to determine the thermal structure in LHDAC experiments. Based on these insights we have been able to develop a simple analytical model that allows us to predict the axial temperature distribution to within 10%. The analysis of different experimental geometries shows that the microfurnace assemblage reduces the axial gradient most efficiently, followed by double sided laser heating geometries. These results also indicate that finite-element modeling is a viable tool to assess and design new LHDAC experiments.
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting