Measurements of Electron Beam Intensity and Characteristic Line Radiation from Wire Array Z-pinches on the 1 MA COBRA Pulsed-Power Generator

The majority of the X-ray emission from wire array Z-pinches is concentrated in the soft (sub-keV) part of the spectrum. In addition, the soft X-ray pulse is accompanied by significantly harder emission (multi-keV) that is generated at almost the same time. Important questions for wire array Z-pinch physics are: what fraction of the radiated energy is connected with soft versus hard X-rays? What is the nature of the hard X-rays? Previous experiments showed that hard X-rays are connected with energetic electrons generated in wire array Z-pinches as well as X-pinches. Recent experiments have investigated the relationship between electron beam current through the anode of wire array Z-pinches and the characteristic X-ray line intensity from the Z-pinches on the 1 MA COBRA pulsed-power generator. The electron beam current was measured by a low-impedance Faraday cup with a 20 mm diameter collector positioned 25 mm above the anode. The Faraday cup was filtered by thin foils of 15 mum Al, 25 mum stainless steel, or mu50 m stainless steel. X-ray radiation with E > 5 keV was monitored using a Si diode. A wide energy band spectrograph with three spherically bent mica crystals (WB-FSSR) was used to record thermal and characteristic line radiation. We measured electron beams and hard X-rays with sub-nanosecond temporal resolution and spectral lines with ~200 mum spatial resolution. We compared the intensity and timing of soft and hard x-rays, the intensity and relative positions of thermal and characteristic lines, and the intensity and energy of the electron beam in each shot. Through these comparisons, we attempt to determine factors which influence the generation of the electron beams.