Effects of Axial Magnetic Field on the Current Distribution in Z-Pinch Implosion with Pre-Embedded Axial Magnetic Field

We investigate fundamental physics involved in plasma implosion with pre-embedded magnetic field. Reported are the first time spectroscopic measurements of the evolution of the azimuthal magnetic field distribution; the configuration used is magnetized z-pinch plasma. The measurements show that the azimuthal magnetic field in the imploding plasma is substantially smaller than expected from the driving current and the plasma radius, demonstrating a dramatic effect of the pre-embedded axial magnetic field on the current distribution. It is found that even in the presence of a relatively low axial field (compared to the peak azimuthal magnetic-field), the part of the current flows at large radii through non-imploding, lower-density plasma. Considerations based on the development of force- free current configuration are suggested to explain this phenomenon and previous unpredicted observations in higher-power imploding magnetized plasma experiments.