Efficient K-shell emission in a Z pinch with axial magnetic field

Axial magnetic field is known to produce a stabilizing effect on Z-pinch implosions by introducing magnetic shear that suppresses the RT instability. For this mechanism to be effective, Bz has to become comparable to the self-generated azimuthal magnetic field of the pinch. Experiments made some years ago have confirmed the above-mentioned stabilization. Early experiments at UC Irvine and Sandia demonstrated stabilization (high radial compression, elastic bouncing) at high initial Bz. With much of the implosion energy expended on the Bz flux compression, the x-ray output in these experiments was noticeably lower than without axial magnetic field. Experiments conducted at Kurchatov Institute, and HCEI realized stabilization with Bz flux concentrated in or between thin cylindrical shells. This made it possible to achieve stabilization at lower initial Bz, making more energy at stagnation available for radiation. Still, it was not clear whether a trade-off between efficient radiative yield and use of Bz for stabilization could be achieved. We report theoretical and modelling results indicating that this is indeed possible for producing krypton K-shell radiation at current level of tens of MA. Moreover, it was found that the presence of an axial magnetic field could be favourable both for stabilizing the implosion and for increasing the K-shell yield due to the radial structure and dynamics of the radiating plasma. Work sponsored by DTRA.