Driven thermal waves and determination of the thermal conductivity in a magnetized plasma

Karbashewski, Scott; Sydora, R. D.; Compernolle, B. Van; Poulos, M. J.

doi:10.1103/physreve.98.051202

Cited by 6 publications

(3 citation statements)

References 22 publications

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“…Initially, the density is slightly non-uniform with a decrease in the regions of highest temperature; this is in stark contrast to previously documented single filament behaviour that shows enhanced density in the centre of the filament (Karbashewski et al. 2018). By the middle of the discharge any large spatial differences in density have disappeared and by the end of the experiment the variations in density are minimal (note the range of the colour bar).…”

Section: Experiments Resultscontrasting

confidence: 93%

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Drift-Alfvén fluctuations and transport in multiple interacting magnetized electron temperature filaments

et al. 2019

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The results of a basic electron heat transport experiment using multiple localized heat sources in close proximity and embedded in a large magnetized plasma are presented. The set-up consists of three biased probe-mounted crystal cathodes, arranged in a triangular spatial pattern, that inject low energy electrons along a strong magnetic field into a pre-existing, cold afterglow plasma, forming electron temperature filaments. When the three sources are activated and placed within a few collisionless electron skin depths of each other, a non-azimuthally symmetric wave pattern emerges due to interference of the drift-Alfvén modes that form on each filament’s temperature gradient. Enhanced cross-field transport from chaotic ( $\boldsymbol{E}\times \boldsymbol{B}$ , where $\boldsymbol{E}$ is the electric field and $\boldsymbol{B}$ the magnetic field) mixing rapidly relaxes the gradients in the inner triangular region of the filaments and leads to growth of a global nonlinear drift-Alfvén mode that is driven by the thermal gradient in the outer region of the triangle. Azimuthal flow shear arising from the emissive cathode sources modifies the linear eigenmode stability and convective pattern. A steady-current model with emissive sheath boundary predicts the plasma potential and shear flow contribution from the sources.

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Section: Experiments Resultscontrasting

confidence: 93%

“…2008 a , b , c ; Karbashewski et al. 2018). In these experiments a low-voltage electron beam was injected into a strongly magnetized, cold, afterglow plasma.…”

Section: Introductionmentioning

confidence: 99%

Drift-Alfvén fluctuations and transport in multiple interacting magnetized electron temperature filaments

et al. 2019

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“…This basic fact has important, but thus far unaddressed, implications for heat pulse based thermal diffusivity measurements. Such experiments have been widely conducted in magnetic confinement devices since the 1980s [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Yet, many aspects of heat transport in plasmas remain mysterious.…”

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confidence: 99%

Coupled heat pulse propagation in two fluid plasmas

Jin,

Reiman,

Fisch

2020

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Because of the large mass differences between electrons and ions, the heat diffusion in electron-ion plasmas exhibits more complex behavior than simple heat diffusion found in typical gas mixtures. In particular, heat is diffused in two distinct, but coupled, channels. Conventional single fluid models neglect the resulting complexity, and can often inaccurately interpret the results of heat pulse experiments. However, by recognizing the sensitivity of the electron temperature evolution to the ion diffusivity, not only can previous experiments be interpreted correctly, but informative simultaneous measurements can be made of both ion and electron heat channels.

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Stimulated excitation of thermal diffusion waves in a magnetized plasma pressure filament

et al. 2021

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Results are presented from basic heat transport experiments using a magnetized electron temperature filament that behaves as a thermal resonator. Using a small cathode source, low energy electrons are injected along the magnetic field into the afterglow of a pre-existing plasma forming a hot electron filament embedded in a colder plasma. A series of low amplitude, sinusoidal perturbations are added to the cathode discharge bias that creates an oscillating heat source capable of driving large amplitude electron temperature oscillations. Langmuir probes are used to measure the amplitude and phase of the thermal wave field over a wide range of driver frequencies. The results are used to verify the excitation of thermal waves, confirm the presence of thermal resonances, and demonstrate the diagnostic potential of thermal waves through measurement of the parallel thermal diffusivity.

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Driven thermal waves and determination of the thermal conductivity in a magnetized plasma

Cited by 6 publications

References 22 publications

Drift-Alfvén fluctuations and transport in multiple interacting magnetized electron temperature filaments

Drift-Alfvén fluctuations and transport in multiple interacting magnetized electron temperature filaments

Coupled heat pulse propagation in two fluid plasmas

Stimulated excitation of thermal diffusion waves in a magnetized plasma pressure filament

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