Dynamics of an Al wire corona of a megaampere Z-pinch

It is shown that the development of instabilities in a Z-pinch plasma formed by loading a relatively thick At wire (an initial diameter of 120 mum and a maximum discharge current of 2-3 MA) is slowed down due to the high plasma density in the wire corona. A cylindrically symmetric, regular, and stable corona surrounding the wire contains a helical formation with a dense, cold, and magnetized plasma. X-ray pulses with a photon energy of several keV and an FWHM duration of 10-20 ns are generated by a few imploded neck structures in the pinch phase of the corona evolution (70-100 ns after the current onset). The main part of X radiation emitted by individual bright spots in the photon energy range 1.5-2.4 keV (up to 40 J at a peak power of 4 GW) consists of the continuum and the bound-bound transition radiation from H- and He-like At ions. A possible scenario for the axial magnetic field evolution during an X-ray pulse is outlined. (C) 2002 MAIK "Naukal/Interperiodica".