Supersonic jet formation and propagation in x-pinches

Abstract

Observations of supersonic jet propagation in low-current x-pinches are reported. X-pinches comprising of four 7.5 µm diameter tungsten wires were driven by an 80 kA, 50 ns current pulse from a compact pulser. Coronal plasma surrounding the wire cores was accelerated perpendicular to their surface due to the global J × B force, and traveled toward the axis of the x-pinch to form an axially propagating jet. These jets moved towards the electrodes and, late in time (∼150 ns), were observed to propagate well above the anode with a velocity of 3.3 ± 0.6 × 10 4 m/s. Tungsten jets remained collimated at distances of up to 16 mm from the cross point, and an estimate of the local sound speed gives a Mach number of ∼6. This is the first demonstration that supersonic plasma jets can be produced using x-pinches with such a small, low current pulser. Experimental data compares well to three-dimensional simulations using the GORGON resistive MHD code, and possible scaling to astrophysical jets is discussed.

Characterizing the Plasmas of Dense $Z$ -Pinches

“…Astrophysics-relevant bow shocks were produced in nested wire arrays [76], where radiatively cooled plasma streams ablated from the outer wires would flow around the wires of the inner array. It turned out that highly collimated, highMach-number jets can also be produced by a relatively lowcurrent X-pinch discharges [77], [78]. Sheared flows were produced and studied in [79].…”

Development of a Collective Thomson Scattering diagnostic system on SNU X-pinch device

“…The high current through the wires causes Ohmic heating, explodes the wires, creates a dense core plasma (hot spot) and plasma jets which emanate from hot spot. The plasma jets generated by X-pinch plasma have potential applications in various fields, including magneto-hydrodynamics physics and astrophysics [3]. To achieve active and quantitative diagnostics of these X-pinch plasma jets, the Collective Thomson Scattering (CTS) diagnostic system has been developed on SNU X-pinch device.…”

Laboratory plasma physics experiments using merging supersonic plasma jets

“…Plasma jet and shock studies on PLX complement many other related, contemporary experimental efforts. Examples include studies of plasma jet dynamics, interactions, and/or shock formation in astrophysically or fusion-relevant contexts using a variety of plasma formation methods, ranging from coaxial plasma guns (e.g., Moser & Bellan 2012) to wire-array-driven pinches (e.g., Haas et al 2011;Gourdain & Seyler 2013;Swadling et al 2014) to laser-driven experiments (e.g., Ross et al 2013;Li et al 2013;Fox et al 2013;Fiksel et al 2014). In general, PLX plasmas are colder and more collisional than the other experiments, but have the benefits of larger spatial size for ease of diagnostic measurements, more choices for the working plasma species, and the option of both unmagnetized and magnetized experiments.…”

“…Bellan et al 2005;Hsu and Bellan 2005;Moser and Bellan 2012) to wire-array-driven pinches (e.g. Haas et al 2011;Gourdain and Seyler 2013;Swadling et al 2014) to laser-driven experiments (e.g. Fox et al 2013;Li et al 2013;Ross et al 2013;Fiksel et al 2014).…”