X-ray Emission of Multiwire $Z$-Pinches in Energy Range Over 20 keV

The results concerning the emission of hard X-rays (HXRs) with an energy over 20 keV from the plasma of dense radiating
Z
-pinches are considered. The work aims at identifying the nature of the fast-electron (electron-beam) generation at the implosion of cylindrical and conical multiwire arrays (liners) at a current up to 3 MA on the Angara-5-1 installation. An effect of zippering on a time profile of HXRs at the implosion of conical arrays that is caused by an inclination of wires was revealed. It was shown that the generation of HXRs always correlates with the disruption of a plasma column near the cathode in the final phase of pinch compression. The pinch images in HXRs are attributed to the emission of bremsstrahlung of fast electrons generated at the plasma column disruption on the plasma ions and in the anode target. It was also found that using conical arrays makes it possible to control the plasma zippering direction, to regulate the space-temporal and power characteristics of X-ray emission, and, in particular, to change the HXR yield. For 12 mm-diameter multiwire arrays with a linear mass 200-400 mug/ cm the current and energy of the fast electrons is estimated to be ~ 20 kA and ~ 60 J, respectively, which make ~ 0.002 of the energy of the soft-X-ray pulse.