Interaction of a supersonic, radiatively cooled plasma jet with an ambient medium

Abstract

An experimental investigation into the interaction of a supersonic, radiatively cooled plasma jet with argon gas is presented. The jet is formed by ablation of an aluminum foil driven by a 1.4 MA, 250 ns current pulse in a radial foil Z-pinch configuration. The outflow consists of a supersonic (Mach number ∼3–5), dense (ion density ni ∼ 1018 cm−3), highly collimated (half-opening angle ∼2°−5°) jet surrounded by a lower density halo plasma moving with the same axial velocity as the jet. The addition of argon above the foil leads to the formation of a shock driven by the ablation of halo plasma, together with a bow-shock driven by the dense jet. Experimental data with and without the presence of argon are compared with three-dimensional, magneto-hydrodynamic simulations using the GORGON code.

Diagnosing collisions of magnetized, high energy density plasma flows using a combination of collective Thomson scattering, Faraday rotation, and interferometry (invited)

“…Careful design of the load allows the geometry of the flows to be controlled and focused in order to produce quasi-1D flows, 6,7 cylindrically symmetric interactions, 8 or jet into ambient medium interactions. 9,10 The collisional scale lengths of the interactions can be tuned both through the choice of the element used to produce the plasmas (typically tungsten or aluminium) and through control of the timing of measurements, allowing the study of both shock formation and long-range flow interpenetration. The current-driven acceleration mechanism used in these experiments means that the plasma flows are magnetised at the point of launch and estimates of the relevant magnetic Reynolds numbers indicate that in many cases this field is advected along with the flows into the interaction region.…”

Influence of atomic kinetics in the simulation of plasma microscopic properties and thermal instabilities for radiative bow shock experiments

“…It deals with the experimental modeling of astrophysical processes, involving studies of microphysics [1][2][3] and large-scale flow phenomena [4][5][6]. Two developments in the field have contributed to the successful design of HED laboratory astrophysical experiments.…”

“…These structures are named bow shocks and their origin are the interaction with the surrounding medium. In the laboratory experiment under consideration in this work, the jet (see Suzuki-Vidal et al [4]) was produced on the MAGPIE generator and was formed by ablation of an aluminum foil driven by a 1.4-MA, 250-ns current pulse in a radial foil Z-pinch configuration.…”

“…The second objective is to perform a study of the influence of the population kinetic models employed to calculate the plasma microscopic properties and to predict the possibility of thermal instabilities by radiative cooling in a particular HED laboratory astrophysics experiment where a radiative bow shock was generated by a radiatively cooled aluminum plasma jet in argon ambient gas [4]. Astrophysical jets are long, supersonic, and collimated outflows that can be observed emerging from a large variety of astrophysical objects, such as the nuclei of active galaxies, neutron stars, gamma ray bursts, or young stellar objects, among others [31].…”

Experimental studies of supersonic radiatively cooled plasma jets

“…The jet has a flow velocity (50-100 km/s) comparable to those of the astrophysical jets (∼200 km/s) and an aspect ratio (length/radius ∼20) sufficient for designing a scaled jet-ambient interaction experiment under conditions when radiative cooling is playing a significant role. The first set of such experiments was performed using Ar ambient gas occupying all space above the foil (Suzuki-Vidal et al 2012). In this case, both the jet formation and propagation were affected.…”