Pressure and Energy Balance of Stagnating Plasmas in $z$-Pinch Experiments: Implications to Current Flow at Stagnation

Detailed spectroscopic diagnostics of the stagnating plasma in two disparate $z$ pinches allow, for the first time, the examination of the plasma properties within a 1D shock wave picture, demonstrating a good agreement with this picture. The conclusion is that for a wide range of imploding-plasma masses and current amplitudes, in experiments optimizing non-Planckian hard radiation yields, contrary to previous descriptions the stagnating plasma pressure is balanced by the implosion pressure, and the radiation energy is provided by the imploding-plasma kinetic energy, rather than by the magnetic-field pressure and magnetic-field-energy dissipation, respectively.