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Wire Array Z-Pinch Experiments

Figure: a) Laser probing image of 2 ablating wires – one coiled, one straight - in 8 wire array. b) 3D MHD simulation of plasma flow around one coil – green is a density contour of 0.08kgm-3, blue 0.016kgm-3. S.V. Lebedev, J.P. Chittenden, S.N. Bland, S.C. Bott, G.N. Hall, A. Harvey-Thompson, J. Palmer, F. Suzuki-Vidal, M. G. Haines

The implosion of a wire array z-pinch releases huge bursts of X-ray radiation suitable for heating ICF experiments. The stability of these implosions, and hence the level X-ray emission, depends upon how the wires in the array are ablated prior to implosion. On the MAGPIE facility we discovered that the ablation of the wires in an array has a characteristic perturbation, which is usually uncorrelated between neighbouring wires. We have developed a technique to control the wavelength of these perturbations by modifying the topology of the magnetic field using coiled wires. This has allowed more control over the subsequent implosion of the array and may lead to increases in X-ray power.

Figure:
a) Laser probing image of 2 ablating wires – one coiled, one straight - in 8 wire array.
b) 3D MHD simulation of plasma flow around one coil – green is a density contour of 0.08kgm-3, blue 0.016kgm-3.

The figure shows the plasma flowing from a coiled wire has a wavelength determined by the coil, whilst that in the adjacent straight wire has a “natural” wavelength of 0.5mm. This change in wavelength is also seen in 3D MHD simulations from the GORGON code developed within the group.