HEDP produced on the university-scale Z-pinch generators: From X-pinches to wire arrays and applications to astrophysics

A university-scale Z-pinch generator is able to produce HED plasmas within a broad range of temperatures and densities depending on the type of load configurations and wire materials. Experiments with very different Z-pinch loads were performed on 1 MA Zebra generator at UNR and analyzed during the last five years: X-pinch, Cylindrical, Nested, and various types of Planar Wire Arrays (PWA). X-pinches are very good sources of x-rays and can be used for studying radiative properties of high density (≫10 22 cm −3 ) and temperature (≫ 2 keV) plasmas with scales from a few µm to several mm in size. They yield short (few nsec) x-ray bursts from one or several bright plasma spots near the wire cross point and produce strong electron beams as well as plasma jets. PWAs, a new type of the wire array load, were tested in single and multi-plane configurations. It was shown that PWAs may produce significant radiation yield in a ns-scale (up to 25 kJ) and generate bright spots of sub-mm size. The main focus of this presentation is the comparative analysis of the results from recent experiments with the X-pinch, Cylindrical and Nested Wire Arrays and PWAs made from stainless steel wires. The diagnostic set included XRD and PCD detectors, laser shadowgraphy, x-ray time-gated and time integrated imaging, time integrated spatially resolved spectrometers for harder (K-shell) and softer (L-shell) x-ray regions, and a time-gated spatially integrated spectrometer for the softer (L-shell) x-ray region. The non-LTE kinetic, WADM, and MHD codes are used to guide the analysis of the results. In particular, the new results for X-pinches with different angles between the wires are presented and their relevance to astrophysics is demonstrated. The new results from the experiments with above-mentioned wire array loads focus on the study of precursor formation as well as plasma evolution at the stagnation phase. The unique properties and HED features of such plasmas are summarized and discussed.