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Title: Laser heating of an absorbing and conducting media applied to laser flash property measurements

Abstract

The laser flash technique is widely used for determining the thermal diffusivity of a sample. In this work, the temperature distribution throughout the sample is investigated, identifying localized, highly-heated regions near the front surface of the sample as a function of: (1) pulse duration, (2) incident beam uniformity, and (3) sample opacity. These high-temperature regions result in an increase in the uncertainty due to temperature-dependent properties, an increase in the heat loss from the sample, and an increased risk of sample damage. The temperature within a semi-transparent media is also investigated in order to establish a regime for which the media can reasonably be considered as opaque. This analysis illustrates that, for same total energy deposition, treatment of the incident energy as a continuous heat source, as opposed to an infinitesimal pulse of energy, results in a factor of 2 increase in the front surface temperature during heating. Also, for the same total energy deposition and approximate beam size, use of a Gaussian intensity distribution increases the front surface temperature during heating by more than a factor of 2 as compared to the use of a uniform temperature distribution. By analyzing the front surface temperature of an absorbing and conductingmore » semi-transparent sample subjected to a Gaussian intensity distribution, it is concluded that the media can be treated as opaque, (i.e. the energy can be applied as a boundary condition) for {var_epsilon} = kd > 50, where k is the extinction coefficient and d is the beam diameter. For materials with a sufficiently small absorption coefficient and thermal diffusivity, a closed-form solution suitable for design use is presented for the front-surface temperature at a location coincident with the beam centerline.« less

Authors:
 [1];  [2]
  1. Sandia National Labs., Albuquerque, NM (United States)
  2. Texas Tech Univ., Lubbock, TX (United States). Dept. of Mechanical Engineering
Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10136270
Report Number(s):
SAND-93-1716C; CONF-941143-1
ON: DE94008942; BR: GB0103012
DOE Contract Number:  
AC04-94AL85000; AC04-76DP00789
Resource Type:
Conference
Resource Relation:
Conference: Thermal conductivity 22,Tempe, AZ (United States),7-10 Nov 1994; Other Information: PBD: [1993]
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION; THERMAL DIFFUSIVITY; MEASURING METHODS; LASER SPECTROSCOPY; TEMPERATURE DISTRIBUTION; ENERGY DEPOSITION; TEMPERATURE MEASUREMENT; MEASURING INSTRUMENTS; 440500; THERMAL INSTRUMENTATION

Citation Formats

Gritzo, L.A., and Anderson, E.E. Laser heating of an absorbing and conducting media applied to laser flash property measurements. United States: N. p., 1993. Web.
Gritzo, L.A., & Anderson, E.E. Laser heating of an absorbing and conducting media applied to laser flash property measurements. United States.
Gritzo, L.A., and Anderson, E.E. Fri . "Laser heating of an absorbing and conducting media applied to laser flash property measurements". United States. https://www.osti.gov/servlets/purl/10136270.
@article{osti_10136270,
title = {Laser heating of an absorbing and conducting media applied to laser flash property measurements},
author = {Gritzo, L.A. and Anderson, E.E.},
abstractNote = {The laser flash technique is widely used for determining the thermal diffusivity of a sample. In this work, the temperature distribution throughout the sample is investigated, identifying localized, highly-heated regions near the front surface of the sample as a function of: (1) pulse duration, (2) incident beam uniformity, and (3) sample opacity. These high-temperature regions result in an increase in the uncertainty due to temperature-dependent properties, an increase in the heat loss from the sample, and an increased risk of sample damage. The temperature within a semi-transparent media is also investigated in order to establish a regime for which the media can reasonably be considered as opaque. This analysis illustrates that, for same total energy deposition, treatment of the incident energy as a continuous heat source, as opposed to an infinitesimal pulse of energy, results in a factor of 2 increase in the front surface temperature during heating. Also, for the same total energy deposition and approximate beam size, use of a Gaussian intensity distribution increases the front surface temperature during heating by more than a factor of 2 as compared to the use of a uniform temperature distribution. By analyzing the front surface temperature of an absorbing and conducting semi-transparent sample subjected to a Gaussian intensity distribution, it is concluded that the media can be treated as opaque, (i.e. the energy can be applied as a boundary condition) for {var_epsilon} = kd > 50, where k is the extinction coefficient and d is the beam diameter. For materials with a sufficiently small absorption coefficient and thermal diffusivity, a closed-form solution suitable for design use is presented for the front-surface temperature at a location coincident with the beam centerline.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1993},
month = {12}
}

Conference:
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