The evolution of the sheath of the dense plasma focus as applied to intense auroral observations

Summary form only given. This paper investigates the dense plasma focus (DPF) for applications in space plasma physics. The plasma focus (a variant of Z-pinch) generates plasmas from fast high voltage electrical discharges on coaxial electrodes suitable for very different studies: from fusion up to plasma space modeling. In particular, the plasma sheath of the DPF is here studied and measured in some detail as a possible model for auroral observations. The sheath presents four main stages during its brief evolution (less than 1 microsecond): coaxial or run-down, roll-off, radial compression and bubble formation. At the end of the radial compression the bulk of the plasma in our experiments is a pinch in which the Bennett equation is fulfilled on average. We report the recording of about 60 current filaments along the sheath, from run-down to radial compression stages in front-on and oblique-on views, time-referred to the total current derivative