Abstract Details
Abstracts
Author: Richard D. Sydora
Requested Type: Consider for Invited
Submitted: 2025-02-19 19:58:34
Co-authors: S.G. Karbashewski
Contact Info:
University of Alberta
116 Street, 85 Avenue
Edmonton, Alberta T6G2E1
Canada
Abstract Text:
Thermal waves are a diffusive-type oscillation with propagation characteristics and behave similar to a “standard wave”. Over the past few decades thermal waves have been used extensively to study the optical, thermal and electronic properties of solids, liquids and gases and more recently have been used in magnetized plasmas. Thermal waves are produced using sinusoidally time-varying heat sources and can be generated through external wave sources, such as electron cyclotron heating in toroidal plasmas or through an oscillatory electron beam source. In basic heat transport experiments using driven thermal waves in a magnetized plasma pressure filament, we have mapped out the amplitude and phase of the thermal wave field over a wide range of driver frequencies (S. Karbashewski, et al, Phys. Plasmas, 28, 092112 (2021)). The results reveal a complex cross-field structure that is shown to be due to thermal wave interference effects from the inhomogeneous structure of the filament. In this new work, a classical mechanics approach based on the Hamilton-Jacobi thermal harmonic oscillator formulation is used to model the inhomogeneous thermal conductivity profile to accurately predict the observed thermal wave interference patterns and extract thermal conductivities. A comparison of the observations in quiescent and turbulent conditions demonstrates thermal waves may be used to distinguish between classical and anomalous transport regimes. In order to develop a model for 2D anisotropic inhomogeneous thermal diffusivity, a field theory approach is used since there is a thermal field flux associated with each spatial coordinate. This leads to a de Donder-Weyl Hamilton-Jacobi equation (DWHJ) that can yield the thermal wave field as a function of two spatial coordinates (r,z) and frequency. Results of this analytical model are validated against measurements from experiments carried out in a linear magnetized plasma device.
Characterization: 4.0
Comments: