Location

La Jolla, CA

Start Date

1-1-1987 12:00 AM

Description

The ability of thermal waves to perform non-destructive depth-profiling studies in materials with spatially variable thermal/thermodynamic properties has been exploited mostly qualitatively so far. The lack of appropriate general theoretical models in the literature has been largely responsible for the near absence of quantitative depth-profiling, especially in media with large thermal property variations within depths on the order of the thermal wavelength. As a result of mathematical difficulties, theoretical treatments have been essentially confined to discrete, multilayered solid structures with constant thermal and thermodynamic properties within each thin layer [1,2]. Furthermore, Afromowitz et al. [3] have applied discrete Laplace transformations to the heat conduction equation to treat the production of the photoacoustic signal in a solid with continuously variable optical absorption coefficient as a function of depth, however, the thermal parameters of the solid were assumed constant. Thomas et al. [4] calculated the Green’s function for the three-dimensional heat conduction equation describing thermal wave propagation in a thermally uniform solid with a subsurface discontinuity (“flaw”). More recently, Jaarinen and co-workers [5,6] used Finite Difference and Inverse methods for thermal wave depth-profiling of samples with spatially variant thermal properties from measurements of the surface temperature distribution. Aamodt and Murphy [7] very recently used vector/matrix methods to calculate thermal wave responses from discretely layered samples. These authors further considered the case of continuously varying thermal properties as the limit of infinitely thin layers.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

6A

Chapter

Chapter 1: General Techniques—Fundamentals

Section

Thermal Waves

Pages

227-235

DOI

10.1007/978-1-4613-1893-4_26

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Classical and Quantum Mechanical Aspects of Thermal Wave Physics

La Jolla, CA

The ability of thermal waves to perform non-destructive depth-profiling studies in materials with spatially variable thermal/thermodynamic properties has been exploited mostly qualitatively so far. The lack of appropriate general theoretical models in the literature has been largely responsible for the near absence of quantitative depth-profiling, especially in media with large thermal property variations within depths on the order of the thermal wavelength. As a result of mathematical difficulties, theoretical treatments have been essentially confined to discrete, multilayered solid structures with constant thermal and thermodynamic properties within each thin layer [1,2]. Furthermore, Afromowitz et al. [3] have applied discrete Laplace transformations to the heat conduction equation to treat the production of the photoacoustic signal in a solid with continuously variable optical absorption coefficient as a function of depth, however, the thermal parameters of the solid were assumed constant. Thomas et al. [4] calculated the Green’s function for the three-dimensional heat conduction equation describing thermal wave propagation in a thermally uniform solid with a subsurface discontinuity (“flaw”). More recently, Jaarinen and co-workers [5,6] used Finite Difference and Inverse methods for thermal wave depth-profiling of samples with spatially variant thermal properties from measurements of the surface temperature distribution. Aamodt and Murphy [7] very recently used vector/matrix methods to calculate thermal wave responses from discretely layered samples. These authors further considered the case of continuously varying thermal properties as the limit of infinitely thin layers.