The formation of supersonic, radiatively cooled plasma jets with applications to laboratory astrophysics has been an active area of research on the MAGPIE generator. One of the ways of producing astrophysically-relevant jets in the laboratory is by using the ablation of plasma from a radial foil Z-pinch. In this configuration a similar to 1.4 MA, 250 ns current pulse is introduced into an aluminium disk with a thickness of 15 p mu m. The ablated plasma from the foil converges on the axis, producing a steady and collimated jet with a typical axial velocity of similar to 100 km/s. The setup allows for the addition of argon above the foil for jet-ambient interaction studies. The interaction is characterised by the formation of several shock features, which are presented and discussed from experimental data and numerical simulations.

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.

Laboratory astrophysics is a novel approach to study different types of astrophysical phenomena by the means of carefully scaled laboratory experiments. Particularly, the formation of highly supersonic, radiatively cooled plasma jets for the study of protostellar jets is an active area of research at present. At Imperial College London, different experimental configurations allow producing plasma flows which are scalable to protostellar jets. The plasma is produced by introducing a ∼1.4 MA, 250 ns current pulse from the MAGPIE generator into a load. By varying the geometry of the load it is possible to study different regions of interest in the jet. For instance, the effect of magnetic fields in the launching and collimation of the jet, and the propagation of the jet far away from the launching region as it interacts with the ambient medium. Two main experiments can address such regions of interest: radial wire arrays and radial foils. By using a radial wire array it is possible to produce a jet driven by a predominant toroidal magnetic field on the axis of a magnetic "bubble", which expands with velocities up to ∼300 km/s. In a radial foil the wires are replaced by a continuous disk allowing to produce a hydrodynamic jet, i.e. a jet in which magnetic fields are not dynamically significant. With this particular configuration it is possible to introduce a neutral gas above the foil in order to study jet-ambient interactions. Experimental results from different diagnostics will be presented together with 3-D MHD simulations using the GORGON code.

A supersonic (Mach similar to 2-3), radiatively cooled plasma jet is produced by the ablation of aluminium plasma from a radial foil, a disc subjected to a similar to 1.4 MA, 250 ns current from the MAGPIE pulsed-power generator. The ablated plasma converges on axis, producing a steady and collimated jet with axial velocities reaching similar to 100 km/s. The study of jet-ambient interactions is achieved by introducing a neutral gas above the foil using a fast valve with a supersonic gas nozzle. The system has flexibility to study different interaction geometries in order to vary critical dimensionless parameters for astrophysical studies. In particular the effects of radiative cooling on the working surface of the jet are strongly affected by varying the gas composition. Experimental results are compared to numerical simulations using the 3-D MHD code GORGON. (C) 2012 Elsevier B.V. All rights reserved.

Properties of radiatively cooled supersonic plasma jets formed by ablation of thin Al foils driven by 1.4 MA, 250 ns current pulse are presented. The jets are highly collimated with half-opening angles of similar to 2 degrees. Measurements of the flow velocity (similar to 60 km/s) and plasma temperature (similar to 15 eV) in the jet with Thomson scattering diagnostic give internal Mach number of M similar to 3, suggesting additional collimation of the jet by toroidal magnetic fields.

Preliminary results of the interaction of a supersonic, radiatively cooled plasma jet with an ambient gas are presented. The experimental setup consists of a radial foil, a mum-thick aluminium disc held between two concentric electrodes and subjected to a 1.4 MA, 250-ns current pulse from the MAGPIE generator. The plasma flow, with typical velocities of ~70–90 km/s, is produced by the J × B force acting on the plasma ablated from the foil. A jet is formed from the convergence of this ablated plasma on the axis of the system. A new setup allows the jet to interact with an argon ambient (particle density N ~1016-17 cm−3) from a supersonic gas nozzle (Mach ~9). First results are characterised by the presence of several (previously unseen) shock structures, which are formed from the interaction of the jet with the argon ambient.

Summary form only given. We have previously reported on the designs of triple shell nozzles, 8 and 12 cm in diameter, for use at >;20 MA on the Z generator. Here we describe the characterization of the cold gas flow, a critical input for shot preparations on Z as well as MHD modeling of the implosions. Two types of interferometer have been used for the measurements. One, a fiber optic infrared (FOI) Mach Zehnder design has been in use for many years in our lab. A millimeter diameter beam at 1.55 micron is scanned across the nozzle diameter. The full time history of the flow is captured with a photodiode and digitizer. The puff valves must be fired many times (~150) to get 2 mm radial resolution and averaging at each position to improve signal to noise. Practical axial resolution is 10 mm. Data reduction to average shots, derive phase and then Abel-invert the data is quite time consuming. However, the use of the FOI has the benefit that the durability of the puff valve system can evaluated, optimized and ultimately demonstrated with such rigorous testing. We have also recently assembled a 2D Mach-Zehnder design using a HeNe laser at 633 nm and a low cost interline transfer 5 megapixel CCD. With only a few shots of the puff valves, full 2D maps of gas density can be derived with sub millimeter resolution in both R and Z. The field of view exceeds 8 cm in R and 4 cm in Z. The time resolution is <;20 microseconds, more than sufficient to characterize the flow once it reaches its "steady-state". Data from both interferometer systems will be compared. In addition, by using different gases in the three plena, we can derive data on the contributions of each plenum to the gas at each R,Z location.