Pulsed-power-driven cylindrical aluminium liner implosions with a high aspect ratio at an 8 MA facility

Lü, Jian; Yan, Xiaosong; Meng, Shijian; Ning, Jiamin; Jiang, Shuqing; Chen, F. X.; Zhi-jian, Huang; Yang, Ruihua; Ye, F.; Xu, Rongkun; Zhang, Xu; Li, Z. H.

doi:10.1088/1741-4326/aba0c7

Cited by 7 publications

(3 citation statements)

References 33 publications

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“…where I thr is the threshold pinch current below which AT instabilities prevail over MHD instabilities. When the pinch current through is lower than I thr , the ratio of the development times of AT and MHD instabilities decreases rapidly with decreasing pinch current, as we have τAT τMHD ∼ ( I I thr ) 4 . So, even for I = 0.5I thr , we have τ MHD ≈ 16τ AT ; that is, AT instabilities should entirely prevail over MHD instabilities.…”

Section: Comparison Of the Parameters Characterizing The Development ...mentioning

confidence: 84%

“…A pinch is a high-current electrical discharge in a currentcarrying material, which, being compressed by the induced magnetic field, is heated to high temperatures [1][2][3][4]. Pinches are widely studied both as powerful sources of soft x-rays [5][6][7][8][9] and as candidates for use in inertial confinement fusion experiments [1][2][3][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

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Thermal instabilities in micropinches under turbulent heating conditions

Oreshkin¹,

Artyomov²,

Oreshkin³

2022

Plasma Phys. Control. Fusion

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Anomalous thermal instabilities occurring in micropinches are analyzed based on the theory of small perturbations. Instabilities of this type develop in a high-temperature plasma under turbulent heating conditions in the presence of an anomalous resistance resulting from the scattering of electrons by lower hybrid drift oscillations. When turbulent heating occurs in the plasma of a micropinch, its resistivity increases with decreasing density; this may lead to the formation of plasma layers normal to the current flow (stratification). For the anomalous thermal instability, a dispersion relation taking into account the effect of the plasma self-radiation has been derived, and the characteristic instability growth rates and wavelengths have been determined. A comparison of the development pattern has been performed between anomalous thermal and sausage-type magnetohydrodynamic instabilities. It has been shown that for any pinch material, there is a threshold current below which anomalous thermal instabilities prevail over magnetohydrodynamic instabilities. For the metals considered (aluminum, titanium, copper, molybdenum, and tungsten), the threshold currents are hundreds of kiloamperes. The threshold current increases with atomic number: for tungsten, it is approximately 3.5 times higher than for aluminum. The conclusions drawn from the analysis based on the linear small perturbation theory are compared with the results of experiments in which the parameters of "hot spots" formed in X pinches were determined.

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Section: Comparison Of the Parameters Characterizing The Development ...mentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Thermal instabilities in micropinches under turbulent heating conditions

Oreshkin¹,

Artyomov²,

Oreshkin³

2022

Plasma Phys. Control. Fusion

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“…The high-opacity Z-pinch plasma traps the radiation, serving as the hohlraum wall to increase x-ray intensity and achieve a high radiation temperature. Compared to wire-array Z-pinch, it can better trap the radiation and reach a higher radiation temperature because of the absence of inter-wire gap spacing in the liner Z-pinch [10,11].…”

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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Visualizing magnetically driven converging radiative shock generated in Z-pinch foil liner implosion

Meng

Zhang

et al. 2021

Physics of Plasmas

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A study of the evolution and structure of magnetically driven converging radiative shock waves generated in Z-pinch foil liner implosion at an 8-MA pulsed-power facility is presented. End-on extreme ultraviolet images show an inward propagating shock that is circular to <±5% as a function of azimuthal angle, with a standard deviation in the emission intensity of <±30%, implying good cylindrical symmetry. The launch time and shock trajectory are determined by linear fitting of the measured data, giving a shock speed of Mach 6. One-dimensional radiation hydrodynamics MULTI-IFE-Z simulations agree with the experimental observations qualitatively and confirm the existence of a radiative precursor. It is demonstrated with experiment and simulation that the radiative shock wave is generated by magnetic piston compression of dense plasma shell. Analytic estimates of the post-shock plasma conditions suggest that these Z-pinch magnetically-driven high-Mach shocks are strongly radiatively cooled. It is applicable to the optically thick downstream, optically thin upstream radiative shock regime; thus, it can be described by three-layer model, which potentially could be applied to scale studies of astrophysical shocks in the laboratory.

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Pulsed-power-driven cylindrical aluminium liner implosions with a high aspect ratio at an 8 MA facility

Cited by 7 publications

References 33 publications

Thermal instabilities in micropinches under turbulent heating conditions

Thermal instabilities in micropinches under turbulent heating conditions

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

Visualizing magnetically driven converging radiative shock generated in Z-pinch foil liner implosion

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