Plasma dynamics in the self-magnetic-pinch diode
The self-magnetic-pinch (SMP) diode1,2 is being developed as a source for flash x-ray radiography. The high electric field stresses applied to this diode and material heating from the intense electron beam generate electrode plasmas. While these plasmas are instrumental in beam formation and focusing, rapid plasma expansion from the electrodes can degrade radiographic performance.
An optical streak diagnostic for observing anode-cathode plasmas for radiographic source development
National Security Technologies and Sandia National Laboratories are collaborating in the research and development of pulsed-power-driven intense electron beam sources for x-ray radiography. These diode sources typically generate electrode plasmas with densities of 1013-1017 cm-3, and understanding these plasmas is critical for optimizing the radiographic performance. NSTec has developed and fielded two systems which provide temporally and spatially resolved measurements of plasma density distributions. Details of the hardware are provided along with example measurement results.
EFFECT OF SAMPLE PREPARATION ON WATER TREE RESISTANCE OF XLPE/SEBS BLENDS
The effects of an aromatic polymer, such as poly[styrene-b-(ethylene-co-butylene)b-styrene] (SEBS), and its preparation processes on water tree resistance, morphology, crystallinity, dielectric constant and dielectric loss tangent of crosslinked polyethylene (XLPE)/SEBS and XLPE/SEBS/ethylene vinyl acetate (EVA) blends were investigated. The XLPE/SEBS samples were characterized by means of differential scanning calorimetry, scanning electron microscopy, dielectric spectral analysis and the accelerated water treeing experiment. The results clearly showed that although SEBS was partially compatible with LDPE and it was dispersed evenly in XLPE matrix, the blends demonstrated excellent dielectric performances, such as dielectric constant and dissipation factor. The crystallinity of XLPE/SEBS blends was decreased with increase in SEBS content and it was further decreased with the addition of EVA. SEBS could effectively improve the water-tree resistance of XLPE and both SEBS and EVA were found to improve the water tree resistance of XLPE synergistically as expected. The differences in sample preparation processes could change the phase morphology and dielectric performance of the blends, and could also influence the dispersion of SEBS in XLPE matrix as well as the crystallinity of the blends. Different preparation processes led to different water tree resistance behaviours of the samples. The improvement of SEBS dispersion in XLPE matrix helped to improve the water tree resistance of XLPE.