Stabilization of Liner Implosions via a Dynamic Screw Pinch

Magnetically driven implosions are susceptible to magnetohydrodynamic instabilities, including the magneto-Rayleigh-Taylor instability (MRTI). To reduce MRTI growth in solid-metal liner implosions, the use of a dynamic screw pinch (DSP) has been proposed [P. F. Schmit et al., Phys. Rev. Lett. 117, 2...

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Bibliographic Details
Published in:Physical review letters 2020-07, Vol.125 (3), p.1-035001, Article 035001
Main Authors: Campbell, Paul C., Jones, T. M., Woolstrum, J. M., Jordan, N. M., Schmit, P. F., Greenly, J. B., Potter, W. M., Lavine, E. S., Kusse, B. R., Hammer, D. A., McBride, R. D.
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Aluminum
Amplitudes
Fluid flow
Implosions
Linings
Magnetic fields
Magnetohydrodynamics
Metal foils
Screw pinch
Stabilization
Taylor instability
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Summary:Magnetically driven implosions are susceptible to magnetohydrodynamic instabilities, including the magneto-Rayleigh-Taylor instability (MRTI). To reduce MRTI growth in solid-metal liner implosions, the use of a dynamic screw pinch (DSP) has been proposed [P. F. Schmit et al., Phys. Rev. Lett. 117, 205001 (2016)]. In a DSP configuration, a helical return-current structure surrounds the liner, resulting in a helical magnetic field that drives the implosion. Here, we present the first experimental tests of a solid-metal liner implosion driven by a DSP. Using the 1-MA, 100–200-ns COBRA pulsed-power driver, we tested three DSP cases (with peak axial magnetic fields of 2 T, 14 T, and 20 T) and a standard z -pinch (SZP) case (with a straight return-current structure and thus zero axial field). The liners had an initial radius of 3.2 mm and were made from 650-nm-thick aluminum foil. Images collected during the experiments reveal that helical MRTI modes developed in the DSP cases, while nonhelical (azimuthally symmetric) MRTI modes developed in the SZP case. Additionally, the MRTI amplitudes for the 14-T and 20-T DSP cases were smaller than in the SZP case. Specifically, when the liner had imploded to half of its initial radius, the MRTI amplitudes for the SZP case and for the 14-T and 20-T DSP cases were, respectively, 1.1 ± 0.3     mm , 0.7 ± 0.2     mm , and 0.3 ± 0.1     mm . Relative to the SZP, the stabilization obtained using the DSP agrees reasonably well with theoretical estimates.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.125.035001