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

Abstract

An experimental and numerical study of the nanosecond electrical explosion dynamics of bare and dielectric coated metallic wires in vacuum is reported. A table top Z-pinch generator down-tuned to generate a peak current of 40 kA with a rise time of 60 ns is implemented for the experiments in the skin effect mode. Optical probing diagnostics as well as multiphysics-multiphase simulations are used to study the spatiotemporal dynamics of the exploded wire from the solid to the plasma phase. The results show that the inclusion of the dielectric coating mitigates the electro-thermo-mechanical instability growth developed prior to plasma formation, which results in a subsequent reduced magnetohydrodynamic instability growth in the plasma phase. The study offers valuable insights into the understanding of the seeding mechanisms for the generation of plasma instabilities and the efforts for their growth rate suppression.

Effect of tailored density profiles on the stability of imploding Z-pinches at microsecond rise time megaampere currents

“…The instabilities can be suppressed, in particular, by applying axial magnetic fields to Z-pinch loads [2] or by tailoring their radial density profiles [9][10][11][12]. It should also be noted that to suppress MRT instabilities in imploding magnetically accelerated liners, dielectric-coated conductors are used [13][14][15].…”

Progress on the electro-thermo-mechanical instability and its role as seed on plasma instabilities

“…Moreover, experiments demonstrated that the developed and sustained axial wavelength modes in the plasma phase lie in the range of values of the axial perturbations of the ETM instability developed in the elastic phase as calculated by the derived dispersion equation. Coupled FEM-BEMmagnetohydrodynamic (MHD) multiphysics-multiphase simulations [4,28] demonstrated a remarkable agreement with the experiments. This comparison of the results confirmed that the ETM instability plays a crucial role as a seed mechanism for the grow of the preferred instability modes in the plasma phase.…”

“…The experiments were performed using a Z-pinch pulsed power device [4,5,28]. A detailed description of the Z-pinch device, including a 3D design and the functional specifications, can be found in [5].…”

Characterization of an X-ray Source Generated by a Portable Low-Current X-Pinch

“…The distance between the anode and cathode was 15 mm. A detailed description of the pinch device, including a 3D design as well as the functional specifications, is given in [14], while details about the laser-probing plasma diagnostics-such as three-frame Mach-Zehnder interferometry and three-frame focusing shadowgraph layouts-can be found in [16]. Four different two-wire configurations were tested: (1) tungsten (W) wires loaded at an angle between the crossed wires of 55 • , (2) W wires loaded at an angle of 98 • , (3) gold (Au)-plated W wires at an angle of 55 • , and (4) Au-plated W wires loaded at an angle of 98 • .…”

“…The aim of this study is to characterize the X-pinch scheme as an efficient source of soft X-rays. A tabletop pulsed-power plasma generator, hosted at the Institute of Plasma Physics and Lasers (IPPL) of the Hellenic Mediterranean University (HMU) Research Centre, has previously been used for optical probing experiments of Z-pinch [14][15][16] and X-pinch wire configurations [17], and time-integrated X-ray spectroscopic measurements of the radiation produced by X-pinch loads have been performed [18]. Herein, a new analysis of time-resolved soft X-ray emission measurements is performed to provide a secure correlation with the optical probing results.…”