X-ray emission from laser-heated exploding wires

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Abstract
A theoretical model of the magnetohydrodynamic (MHD) motion and radiation emission characterizing dense laser-heated exploding-wire plasma has been developed which solves (numerically) the set of MHD equations coupled with a set of atomic rate equations describing the ionization and radiation dynamics of the plasma. The model has been applied to study the use of a high-powered laser to ionize and heat an aluminium-exploding-wire plasma. Particular attention has been directed towards the radiation emission from such a plasma which includes free-free (bremsstrahlung), free-bound (radiative recombination), and bound-bound (line emission) contributions. Included in the line emission are hard x rays produced by excited-level-to-ground-state transitions in the heliumlike and hydrogenlike ion species. The simulation model does not presently contain reabsorption or transport of the radiation. Laser absorption efficiency and laser energy-to-x-ray conversion efficiencies are studied as functions of laser pulse width, laser intensity, and initial wire diameter. It is found that the x-ray emission depends critically on the laser energy deposition, the plasma density profile, and hydrodynamic motion at the time of laser interaction, and the strength of the plasma current and its subsequent self-consistent, confining magnetic field.

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