Models of radiation yield from wire array implosion at 1 MA Zebra generator

The snowplow and thin shell models that have the analytical solutions in zero dimensions are linked with the ideal magnetohydrodynamic (MHD) and radiation MHD codes to calculate the radiation yield from the imploding wire array loads at 1 MA Zebra generator. Radiation MHD simulations show that the strong radiation cooling affects plasma dynamics at all stages of the implosion and drives plasma into the radiative collapse at the final stage of the implosion. Being applied to the implosion of an Al wire array with the mass per unit length 3.82 mu g/mm, these simulations show that the thermalization of the kinetic energy can be essentially completed when the radius of the imploding pinch shrinks below similar to 10 mu m. If we assume such a perfect compression, then the plasma energy gain will be 10 kJ with total radiation yield of about 5 kJ, while the emitted radiation spectrum will be blackbody-like with an equilibrium temperature of 200 eV. The only effective mechanism of energy coupling for the imploding plasma, driven by the magnetic piston, is the inductive work of the magnetic field due to the motional impedance. However, the mechanism of anomalous plasma heating, acting in the plasma fraction that was left behind the collapsing current sheath, can couple additional energy into the plasma and can explain the variety of radiation performance features. An adequate model of the radiation yield should consider the stagnating z pinch as an object with strong density and temperature gradients.c 2006 American Institute of Physics.