Cross-code verification and sensitivity analysis to effectively model the electrothermal instability

Masti, Robert; Ellison, C. L.; King, Jacob; Stoltz, Peter; Srinivasan, Bhuvana

doi:10.1016/j.hedp.2021.100925

Cited by 7 publications

(1 citation statement)

References 25 publications

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“…When the condensed liner is heated to vaporization, pressure variations by ETI drive expansion along the strata, causing the formation of macroscopic, azimuthally correlated density perturbations at the amplitude of hundreds of micrometers. Such instabilities, which are also known as electro-choric instabilities (ECI), result from the strong dependence of the metal's resistivity to density, providing the seed for MRT instabilities [15,16].…”

Section: Introductionmentioning

confidence: 99%

Study of the electrothermal and MHD instabilities in exploding cylindrical foil liner

Zhang¹,

Wu²,

Zhou³

et al. 2022

Nucl. Fusion

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Experimental and numerical study of the plasma instabilities in electrical exploding cylindrical Al liner is reported. The Al liner with the size of 3 mm in diameter and 10 μm in thickness is exploded on Qin-1 facility (450 ns, 400 kA). Various diagnostics, such as multi-frame laser shadowgraphy, X-ray framing camera, and X-ray backlighting system are developed. The different imaging systems are sensitive to plasma of different areal densities based on the comparison between the experiments and simulation, which can reveal the dynamics of the exploding liner in more details. The laser shadow images show the low-density plasma (~1-2×10^-4 g/cm^2) at the edge of the liner, and both the amplitude and wavelength of the plasma instabilities increase over time, which are considered to be MHD instabilities rather than electrothermal instabilities. During the ablation of the liner, quasi-periodic azimuthally correlated striations are directly observed in EUV self-emission images. Meanwhile, the vertical filaments, which are electrothermal instabilities for plasma under the condition of ∂η/∂T<0, are also observed in EUV self-emission images. The X-ray backlighting images of the exploding liner are obtained by placing an X-pinch load on the current-return path to serve as an X-ray point source (~1 ns, ~10 μm). X-ray backlighting results show the behavior of the high-density plasma (~ 1.89×10^-3 g/cm^2), which includes the transition from the electrothermal to MHD instabilities. At last, we realized a 2D MHD simulation of the exploding liner under the experimental condition, which shows good agreement with the result of the experimental perturbation.

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Section: Introductionmentioning

confidence: 99%

Study of the electrothermal and MHD instabilities in exploding cylindrical foil liner

Zhang¹,

Wu²,

Zhou³

et al. 2022

Nucl. Fusion

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The effect of anomalous resistivity on fast electrothermal instability

et al. 2021

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Effect of surface roughness on phase transition timing in megaampere pulsed-power–driven exploding conductors

Carrier,

Farmer,

Klemmer

et al. 2023

Physics of Plasmas

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An understanding of material phase transitions in megaampere pulsed-power–driven exploding conductors is important for predicting the growth of hydrodynamic instabilities in magneto-inertial fusion concepts. This study analyzes phase transitions in electrical conductor explosions using 1D Lagrangian and 2D arbitrary Lagrangian–Eulerian resistive magnetohydrodynamic simulations to show that micrometer-scale surface roughness can lead to the electrothermal instability (ETI), a feedback effect that concentrates resistive heating and leads to early melting and ablation. Simulations of the Mykonos electrothermal instability II (METI-II) experiment show melting begins 19% sooner for machined rods with micrometer-scale surface roughness than for rods without these features. The surface magnetic field is 41 T around the initial region of melt, representing a lower magnitude than both the 86 T from 1D simulations and the 85 T threshold reported elsewhere. In 2D simulations with micrometer-scale surface roughness, temperature measurements indicate the critical point temperature of aluminum is reached 17% faster in comparison with 1D simulations. Values from 2D simulations with surface roughness align with predictions from ETI theory, and the observed temperature redistribution further supports the ETI as an underlying mechanism. Simulation results are validated against experimental photonic Doppler velocimetry data. This study shows 1D simulations are adequate to model conductors with sub-micrometer-scale surface roughness in this high-energy-density regime; however, 2D or 3D simulations are required to capture the full range of physics for accurately describing phase transitions in conductors with micrometer-scale or larger surface roughness.

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Cross-code verification and sensitivity analysis to effectively model the electrothermal instability

Cited by 7 publications

References 25 publications

Study of the electrothermal and MHD instabilities in exploding cylindrical foil liner

Study of the electrothermal and MHD instabilities in exploding cylindrical foil liner

The effect of anomalous resistivity on fast electrothermal instability

Effect of surface roughness on phase transition timing in megaampere pulsed-power–driven exploding conductors

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