Characteristics of the Energetic Electrons Produced During Implosions of Different Wire Array Loads on 1 MA University-Scale Generators

Abstract

Summary form only given. Experimental studies of the characteristics of the energetic electrons produced in experiments with planar and cylindrical wires arrays on the Zebra generator at UNR and nested and 6 mm diameter cylindrical wire arrays on the COBRA generator at Cornell University have been carried out. In this work, silicon diode signals (filters with lower cut off energies 9kev, 25kev, and 30kev), photo conducting detector (PCD) signals, time-gated images and cold Kalpha lines from time integrated spectra (LiF crystal spectrometer) were analyzed. Some of the energetic electrons were observed in the anode-cathode gap, whereas others were observed near the anode and evidenced through the bombardment of the anode. A comparison of results for different loads and generators is presented. For example, with planar wire arrays, energetic electrons responsible for the hardest X-ray bursts (duration 25-30 ns) appear to begin during the main thermal X-ray peak and less energetic electrons (duration 5-10 ns) appear after the current pulse maximum. By contrast, in the experiments with the nested and compact cylindrical arrays on the Cobra generator at Cornell, shorter duration energetic electron pulses (duration 10-20 ns) appear almost immediately after the thermal X-ray pulse and sometimes also at the end of the current pulse (40-60 ns after the soft X-ray pulse). For the small diameter stainless steel cylindrical wire array, there is only one energetic-electron-generated X-ray burst, which occurs just after the main thermal X-ray pulse. During shots with loads from stainless steel or brass the X-ray bursts associated with energetic electrons also affect signals from the soft X-ray detectors.