X-ray radiography of the overheating instability in underwater electrical explosions of wires

Yanuka, D.; Rososhek, A.; Theocharous, S.; Bland, S. N.; Krasik, Yakov E.; Olbinado, Margie P.; Rack, Alexander; Oreshkin, E. V.

doi:10.1063/1.5089813

Cited by 25 publications

(13 citation statements)

References 34 publications

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“…According to experimental data [16], [150]- [154], the explosion of a wire in vacuum is accompanied by the formation of a low-density plasma corona surrounding a dense core and by the occurrence of strata, alternating layers of increased and decreased density, in the core. As shown earlier, under the conditions of a fast WE, to which this review is devoted, the cause of the formation of strata, which was considered, for instance, in [9], [16], [86], and [155], is the development of ETIs.…”

Section: Formation Of Strata In a Fast We (Eti)mentioning

confidence: 99%

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Wire Explosion in Vacuum

Oreshkin

Baksht

2020

IEEE Trans. Plasma Sci.

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This article presents a review of experimental and theoretical studies devoted to the processes that occur during explosions of wires in vacuum when the current densities in the wire are of the order of 10 8 A/cm 2 and the current density rise rates are no less than 10 15 A/(cm 2 • s). The theoretical background is focused on the transformation of the wire metal into ionized plasma. In particular, the basic physical notions used to describe wire explosions (WEs; state diagram, current action integral, and metal conductivity changes in phase transitions) are given; magnetohydrodynamic equations are described which are used to simulate WEs, and the simulation predictions are discussed together with their reliability. Extensive experimental data on WEs in vacuum are presented which made it possible to describe the corona and core formation and the development of electrothermal instabilities in the core. The data on the energy deposited in a wire exploding in vacuum reported by different authors are compared. In conclusion, problems are discussed that require additional experimental investigations, namely, the role of metastable states in a WE and the mechanism by which the core is shunted.

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Section: Formation Of Strata In a Fast We (Eti)mentioning

confidence: 99%

“…The formation of strata in a fast WE was numerically simulated using a 2-D MHD code [18], [98], [154], [156]. Fig.…”

Section: Formation Of Strata In a Fast We (Eti)mentioning

confidence: 99%

Wire Explosion in Vacuum

Oreshkin

Baksht

2020

IEEE Trans. Plasma Sci.

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“…To find the relationship between temperature and density perturbations, we proceed from the following considerations. If the material in a perturbed region moves at a velocity less than the thermal one, the pressure in this region levels off [29,52]; that is, in our case, the pressure gradient along the azimuth must satisfy the condition ( )…”

Section: Filamentation Modelmentioning

confidence: 95%

Filamentation of the surface plasma layer during the electrical explosion of conductors in strong magnetic fields

Oreshkin

Chaikovsky

Datsko

et al. 2022

Journal of Applied Physics

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A model has been considered to describe the development of a surface discharge over a conductor electrically exploding in a strong magnetic field. A simulation performed using this model has shown that in the initial stage of the conductor explosion, a plasma layer of several tens of micrometers thick with an electron temperature of several electronvolts is formed on the metal surface. Based on the theory of small perturbations, the development of thermal filamentation instabilities that form in the surface plasma layer has been analyzed. The characteristic growth rates and wavelengths of these instabilities have been determined. The theoretical results were compared with the results of experiments performed on the ZEBRA generator (providing load currents of amplitude about 1 MA and rise time about 100 ns) and on the MIG generator (providing load currents of amplitude about 2 MA and rise time about 100 ns). For the conditions implemented with these generators, the filamentation model gives rise times of thermal filamentation instabilities of tens of nanoseconds at characteristic wavelengths of the order of 100 μm. These values are in good agreement with experimental data, which indicates the adequacy of both the surface discharge development model and the filamentation model.

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“…Therefore, the exploding wire should be treated as multi point sources instead of single line source when it comes to launching compression waves into the surrounding water. In order to estimate the influence of stratification on the SWs, two simulation cases of high-pressure gas column expanding in water are set up: initially the two gas columns have identical diameter (0.2 mm), density (uniform and equal to solid copper density 8.9 g cm −3 ) and total internal energy (equal to Joule energy deposition at voltage peak in figure 5(a)); one of them is initialized with alternating [25]. As can be expected, a wavy boundary is formed for the layered gas column; however, the individual SWs generated by each layer merge into a uniform cylindrical wave front after only ∼1 mm radial propagation and thereafter shows no difference from the uniform case (peak pressure difference <2%).…”

Section: Sw Characteristicsmentioning

confidence: 99%

“…More accurate description of UEWE process can be realized by magnetohydrodynamic (MHD) models. Many research institutions including Israel Institute of Technology [18], Imperial College London [19], Institute of High Current Electronics [20], Seoul National University [21], Tsinghua University [22] and Xi'an Jiaotong University [23,24] have developed their own MHD codes; general-purpose MHD codes such as JULIA [25] and ALEGRA [26] were also used to study the UEWE process. Generally speaking, previous studies were usually focused on the exploding wire, for example, to test the accuracy of metal equation of states (EOSs) and conductivity data, to clarify the evolution of the wire state and instabilities, etc, and few on SW characteristics.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional simulation of microsecond-timescale underwater electrical explosion of a copper wire

Shi¹,

Li²,

Hu³

et al. 2022

J. Phys. D: Appl. Phys.

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Underwater electrical wire explosion (UEWE) is an efficient source of underwater shock waves (SWs). In order to efficiently simulate the interaction between the UEWE SW and structures, a coupled model that includes the electric circuit, the exploding wire and the surrounding water is established based on user-subroutines provided by the commercial explicit dynamics software ANSYS AUTODYN. The modeling starts from room temperature by using the tabular wide-range metal equation of state (EOS) and conductivity data. Experimental validation is performed with copper wires exploded by a μs-timescale pulsed discharge. The numerical results show satisfactory consistency with experiments in terms of the current and voltage waveforms, the wire expansion trajectory, the evolution of SW front, the interaction between SW and electrodes and the SW pressure profiles. The main discrepancy lies in the SW amplitude that is ~20% higher in the calculation and the possible reasons are discussed in detail. Based on this approach and with proper modifications to the metal EOS and conductivity data, the interaction between UEWE SWs and structures can be efficiently modeled in 2D and 3D for practical applications.

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X-ray radiography of the overheating instability in underwater electrical explosions of wires

Cited by 25 publications

References 34 publications

Wire Explosion in Vacuum

Wire Explosion in Vacuum

Filamentation of the surface plasma layer during the electrical explosion of conductors in strong magnetic fields

Two-dimensional simulation of microsecond-timescale underwater electrical explosion of a copper wire

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