Measurement of the thermal diffusivity and speed of sound of hydrothermal solutions via the laser-induced grating technique
- Los Alamos National Lab., NM (United States)
We use the laser-induced grating technique to measure the thermal diffusivity and speed of sound of hydrothermal solutions. In this noninvasive optical techniques, a transient gradient is produced in the hydrothermal solution by optical absorption from two crossed, time-coincident nanosecond laser pulses. The grating is probed by measuring the diffraction efficiency of a third laser beam. The grating relaxes via thermal diffusion, and the thermal diffusivity is determined by measuring the decay of the grating diffraction efficiency as a function of the pump-probe delay time. In addition, intense pump pulses produce counterpropagating acoustic waves that appear as large undulations in the transient grating decay spectrum. The speed of sound in the sample is simply the grating fringe spacing divided by the undulation period. The cell is made from a commercial high-pressure fitting and is equipped with two diamond windows for optical access. Results are presented for dilute dye/water solutions with T = 400{degrees}C and pressures between 20 and 70 MPa.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 56968
- Report Number(s):
- CONF-940633-; ISSN 0195-928X; TRN: 95:013005
- Journal Information:
- International Journal of Thermophysics, Vol. 16, Issue 1; Conference: 12. symposium on thermophysical properties, Boulder, CO (United States), 19-24 Jun 1994; Other Information: PBD: Jan 1995
- Country of Publication:
- United States
- Language:
- English
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