Browsing by Author "Tarkenton, G. M."

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    Arrival times for dissipative, nonlinear second-sound waves in solids
    Tarkenton, G. M.; Cramer, Mark S. (American Physical Society, 1995-07-01)
    We extend our original analysis begun in Tarkenton et al. [Phys. Rev. B 49, 11 794 (1994)] to include dissipative effects that are important in real cryogenic systems where nonlinear second sound exists. We present results concerning arrival times of thermal pulses propagated in cryogenic crystals, namely the behavior of the arrival times as a function of pulse amplitude. These arrival times show some surprising effects due to competing nonlinear terms: after decreasing with increasing amplitude, as one would expect, the arrival times start to lengthen due to nonlinear effects and finally saturate at a level slightly above the shortest arrival times. All these surprising effects arise from competing nonlinear terms in the expression for the wave speed. We finally relate these results to the experiment we proposed in our original paper.
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    Nonlinear second sound in solids
    Tarkenton, G. M.; Cramer, Mark S. (American Physical Society, 1994-05-01)
    We study the nonlinear propagation of thermal waves in rigid heat conductors using a model introduced by Ruggeri et al. We derive the lowest-order nonlinear corrections to the wave speed and show that the quadratic nonlinearity can be small for NaF and Bi. The smallness of the nonlinear steepening parameter complicates the wave dynamics, allowing for both forward and backward steepening waves within the same pulse. We show that this mixed condition places limits on the size of admissible discontinuities; we then argue that this limit on the size of shock waves limits the arrival times of thermal signals. Using this, we propose an experiment to measure arrival times to look for this limiting behavior.