X-pinch. Part I

Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.

doi:10.1134/s1063780x15040054

Cited by 102 publications

(40 citation statements)

References 165 publications

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“…1a), made 20 ns later, a cavity is seen at the neck place that was formed obviously due to the explosion of the hot spot. Similar pictures were obtained [20,21] for X pinches also consisting of two molybdenum wires of diameter 17 µm the current through which at the time of the explosion was 150-170 kA. These images, taken in soft x rays, clearly demonstrate the explosion of the hot spot.…”

supporting

confidence: 61%

“…At the end, the hot spot explodes and at this time, hard x rays and high-energy ions are generated. The ions appear with a slight delay after the main pulse of soft x rays [21]. This scenario is illustrated by Figs.…”

mentioning

confidence: 82%

“…This feature of X pinches served as the key to the success of experimental studies of the evolution of the neck and the hot spot [20,21].…”

mentioning

confidence: 99%

“…In an X pinch, the hot spot is formed according to the following scenario [20][21][22]. Within a short time after the start of the current flow through the pinch, an electric explosion of the wires occurs.…”

mentioning

confidence: 99%

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Coulomb explosion of “hot spot”

Oreshkin

Chaikovsky

et al. 2016

Physics of Plasmas

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The study presented in this paper has shown that the generation of hard x rays and highenergy ions, which are detected in pinch implosion experiments, may be associated with the Coulomb explosion of the hot spot that is formed due to the outflow of the material from the pinch cross point. During the process of material outflow, the temperature of the hot spot plasma increases, and conditions arise for the plasma electrons to become continuously accelerated. The runaway of electrons from the hot spot region results in the buildup of positive space charge in this region followed by a Coulomb explosion. The conditions for the hot spot plasma electrons to become continuously accelerated have been revealed and estimates have been obtained for the kinetic energy of the ions generated by the Coulomb explosion.A Z pinch is an electrical discharge in plasma, which is compressed under the action of the magnetic pressure produced by the intrinsic discharge current [1][2][3][4][5][6][7]. Typical of Z pinches is the formation of hot spots due to the development of large-scale MHD instabilities [1,2,8-10].The discharge plasma column is deformed during compression, which is accompanied by the formation of necks smaller in radius than the main column. The magnetic pressure in the neck region increases, resulting, first, in faster compression and, second, in material outflow from the neck region in the axial direction. The final stage of the necking is a hot spot.Apparently, the axial jets were first detected in an experimental study [11] where the process of compression of deuterium pinches was investigated. As these jets were accounted for by an increase in neutron yield, the authors of Ref.[11] proposed a "noncylindrical Z pinch" in which the formation of the hot spot was predetermined by the geometry of the discharge.Subsequently, this configuration was called a plasma focus [12,13]. In subsequent experiments on a deuterium plasma focus at currents of about 1 MA, electron beams, hard x rays, and "epithermal" deuterons with energies up to 8 MeV were detected [14]. Even more energetic deuterons with energies of several tens of megaelectron-volts were detected in experiments with deuterium liners imploded at a current of 2.7 MA [15]. To explain the generation of high-energy ions and hard x rays, the so-called "target" mechanism was proposed [16]. It is assumed that in the final stage of formation of the hot spot, displacement currents occur that generate strong electric fields in which charged particles are accelerated.

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supporting

confidence: 61%

mentioning

confidence: 82%

“…This feature of X pinches served as the key to the success of experimental studies of the evolution of the neck and the hot spot [20,21].…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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Coulomb explosion of “hot spot”

Oreshkin

Chaikovsky

et al. 2016

Physics of Plasmas

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“…The plausibility of this chain of events became clear in an extensive set of laboratory studies using Z-pinches, plasma foci and X-pinches (Pikuz et al, 2015a(Pikuz et al, , 2015b. Although not motivated by astrophysical connections, these studies revealed effects that could be of relevance to astrophysics: the formation of energetic, non-thermal ion populations, and generation of particle beams.…”

Section: B Generation Of Energetic Particlesmentioning

confidence: 99%

Exploring astrophysics-relevant magnetohydrodynamics with pulsed-power laboratory facilities

2019

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Laboratory facilities employing high pulsed currents and voltages, and called generally "pulsed-power facilities", allow experimenters to produce a variety of hydrodynamical structures replicating, often in a scalable fashion, a broad range of dynamical astrophysical phenomena. Among these are: astrophysical jets and outflows, astrophysical blast waves, magnetized radiatively dominated flows and, more recently, aspects of simulated accretion disks. The magnetic field thought to play significant role in most of the aforementioned objects is naturally present and controllable in pulsed-power environments. The size of the objects produced in pulsed-power experiments ranges from a centimeter to tens of centimeters, thereby allowing the use of a variety of diagnostic techniques. In a number of situations astrophysical morphologies can be replicated down to the finest structures. The configurations and their parameters are highly reproducible; one can vary them to isolate the most important phenomena and thereby help in developing astrophysical models. This approach has emerged as a useful tool in the quest to better understand magnetohydrodynamical effects in astronomical environments. The present review summarizes the progress made during the last decade and is designed to help readers identify and, perhaps, implement new experiments in this growing research area. Techniques used for generation and characterization of the flows are described. 1 Retired 2 CONTENTS I. Introduction II. Jets and outflows-weak magnetic field A. Generating plasma streams and plasma jets with wire arrays. B. Hypersonic, radiatively cooled hydrodynamic jets and their interaction with the ambient medium C. Hydrodynamic interaction of the jets with a side wind D. Highly-collimated jets produced by ablation of the central area of a metal foil III. Jets and outflows-significant magnetic field A. Magnetically-dominated tower jets B. Formation of energetic ions in a magnetic cavity C. Possible role of axial magnetic field B. Episodic events and internal shocks E. Magnetic arches and their stability F. MHD equilibria stabilized by the shear flow IV. Rotating plasmas-on the way to imitating the accretion discs V. Shock waves A. General comments B. Blast waves and radiative precursors C. Shocks in the colliding streams D. Introducing magnetic field E. Interaction of magnetized streams with clumps and globules VI. Non-MHD effects A. Hall and other two-fluid effects B. Generation of energetic particles C.

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