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One-dimensional ablation in multiwire arrays

Proposed for publication in Physics of Plasmas.

Yu, Edmund Y.; Oliver, Bryan V.; Mehlhorn, Thomas A.

The main physical processes responsible for plasma ablation in multiwire Z pinches are considered via eigensolutions to one-dimensional steady state magnetohydrodynamics. A double scale-length structure of the plasma accelerating layer is demonstrated. The width of the resistive scale-length that defines the current layer structure is significantly larger than the thermal scale-length, where transport of energy toward the cores and plasma pressure play important roles. The transport of energy is provided mainly by radiation, though electron thermal conduction is also important very close to the plasma-core interface. Another type of solution of the steady state problem is revealed, when local Ohmic heating is important down to the interface. Selection between these two types of solutions is considered from multiple points of view. Although the one-dimensional problem is mainly considered in this paper, it is shown how the one-dimensional results may help to understand results of two-dimensional models.

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TYPE Journal Article YEAR 2007
OSTI

Excitation of electromagnetic flute modes in the process of interaction of plasma flow with inhomogeneous magnetic field

Astrophysics and Space Science

Sotnikov, V.I.; Presura, R.; Ivanov, V.V.; Cowan, T.E.; Leboeuf, J.N.; Oliver, Bryan V.

Laboratory experiments on the interaction of a plasma flow, produced by laser ablation of a solid target with the inhomogeneous magnetic field from the Zebra pulsed power generator demonstrated the presence of strong wave activity in the region of the flow deceleration. The deceleration of the plasma flow can be interpreted as the appearance of a gravity-like force. The drift due to this force can lead to the excitation of flute modes. In this paper a linear dispersion equation for the excitation of electromagnetic flute-type modes with plasma and magnetic field parameters, corresponding to the ongoing experiments is examined. Results indicate that the wavelength of the excited flute modes strongly depends on the strength of the external magnetic field. For magnetic field strengths ∼ 0.1 MG the excited wavelengths are larger than the width of the laser ablated plasma plume and cannot be observed during the experiment. But for magnetic field strengths ∼ 1 MG the excited wavelengths are much smaller and can then be detected. © Springer Science+Business Media B.V. 2007.

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TYPE Conference YEAR 2007
ScopusOSTI

Towards a predictive MHD simulation capability for designing hypervelocity magnetically-driven flyer plates and PWclass z-pinch x-ray sources on Z and ZR

Mehlhorn, Thomas A.; Yu, Edmund Y.; Vesey, Roger A.; Cuneo, M.E.; Jones, Brent M.; Knudson, Marcus D.; Sinars, Daniel S.; Robinson, Allen C.; Trucano, Timothy G.; Brunner, Thomas A.; Desjarlais, Michael P.; Garasi, Christopher J.; Haill, Thomas A.; Hanshaw, Heath L.; Lemke, Raymond W.; Oliver, Bryan V.; Peterson, Kyle J.

Abstract not provided.

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TYPE Conference YEAR 2007
OSTI
Results 126–150 of 176
Results 126–150 of 176