The influence of the load’s geometrical characteristics on the generation of the electro-thermo-mechanical instability in a single wire Z-pinch

Abstract

The Z-pinch plasma device is a type of plasma confinement system that uses electrical current to generate a magnetic field which compresses a current-carrying wire. In a previous proof-of-principle study, we demonstrated that in the interaction of a single wire with a pulsed current, the generated Electro-Thermo-Mechanical (ETM) instability in the solid phase acts as a seeding mechanism for the later developed instabilities observed in the plasma phase. In this study, the influence of the geometrical characteristics, such as length and thickness of the load-wire, on the generation of the ETM instability are investigated. Finite element multiphysics-multiphase simulations starting from the solid state are coupled with Magneto-Hydro-Dynamics (MHD) simulations to study the solid to plasma phase transition and the matter’s dynamics. The numerical results of the wire expansion dynamics prior to plasma formation are validated by experimental results from a modified Fraunhofer diffraction diagnostic, while in the plasma phase the simulated plasma dynamics is validated by shadowgraphic and interferometric experimental results. The numerical and experimental results demonstrate a satisfactory agreement for the wire expansion dynamics and the growth rate of the developed instabilities, for varying wire thickness and length.

Instability growth mitigation study of a dielectric coated metallic wire in a low current Z-pinch configuration

“…For the skin effect region of the Cu bare wire, the melting and gas phases are initiated at 45 and 80 ns from the current start respectively, while plasma is formed at 130 ns when the temperature has reached the plasma temperature threshold for Cu (6000 • C) [9], while for the skin effect region of the polyimide coated Cu wire, the corresponding phase transitions occur at 55, 92 and 145 ns respectively. The results of the radial expansion have also been recently validated using a modified Fraunhofer diffraction diagnostic [7][8][9]. For the bare wire, at 130 ns, a radial expansion velocity of 0.18 km s −1 is computed while for the coated wire, at 145 ns, the radial velocity is 0.16 km s −1 .…”

“…The study of the seed physical mechanisms for the generation of plasma instabilities [1][2][3] is of high importance for Z-pinch [4][5][6][7][8][9], X-pinch [10][11][12][13], wire-array Z-pinch [14][15][16][17] and magnetized liner inertial fusion physics [18][19][20][21][22][23][24][25]. We have recently demonstrated that the incorporation of the intrinsic real physical characteristics of the solid material, in a Z-pinch single wire configuration, is essential to understanding the developed electro-thermo-mechanical (ETM) instability which emerges within the solid phase of the interaction [7,9] and is a potential * Author to whom any correspondence should be addressed. seed for the magnetohydrodynamic (MHD) instabilities later observed in the plasma phase of the interaction.…”

High-intensity laser-driven secondary radiation sources using the ZEUS 45 TW laser system at the Institute of Plasma Physics and Lasers of the Hellenic Mediterranean University Research Centre

“…Besides their use for the generation of XUV radiation for dense plasma diagnosis, they are excellent devices for basic plasma physics studies such as for instance plasma instabilities grow. The technical parameters and specifications of these devices can be found in [91][92][93][94][95]. Upon request the devices can be offered to users either as hard X/XUV radiography diagnostics synchronised to the ZEUS laser or as individual plasma sources for experiments.…”

“…The technical parameters and specifications of these devices can be found in Refs. [91][92][93][94][95]. Upon request the devices can be offered to users either as hard X/XUV radiography diagnostics synchronized to the ZEUS laser or as individual plasma sources for experiments.…”