Effect of UV treatment on the dielectric strength of BOPP capacitor film
The effect of UV treatment on dielectric breakdown strength of metallized biaxially-oriented polypropylene (BOPP) capacitor film was studied. Results from Weibull statistical analysis indicate that an optimal UV exposure level of ~3.4 J/cm2 (200-400 nm) increases the breakdown strength at 1% probability by ~20%. UV spectroscopic analysis indicates that the antioxidant in BOPP was consumed almost entirely. The results suggest that antioxidant remaining in the BOPP after processing may have an unfavorable effect on the breakdown strength of the film
High energy density film capacitors
A series of high dielectric constant polymers have been developed with K from 10 to over 50. The high-K polymers have high dielectric breakdown strength above 700 V/µm and high energy density up to 27 J/cc in lab-scale small sample test. The capacitor film was produced by using melt-extrusion and biaxial orientation process and film thickness from 2 µm to 10 µm has been achieved. Metallized prototype capacitors show promising performance with energy density above 3 J/cc. Future development will target at 10 J/cc energy density in the packaged capacitors. Potential applications include pulsed power capacitors for medical defibrillators, high-power X-Ray/laser system, and direct energy weapon systems.
Effect of temperature on optical fiber transmission.
Results are presented concerning the effects of temperature on the transmission properties of various optical fibers including a silicone plastic clad, an acrylic plastic clad, and CVD step-index fibers both with and without polyurethane jackets. Results are presented for the normalized transmitted power vs temperature, the index of refraction vs temperature, and induced attenuation coefficients vs temperature. The data show that the intrinsic transmission of a CVD fiber is independent of temperature over the -110 to +150 C range. Plastic clad fused silica fibers are subject to transmission losses at lower temperatures due to changes in the optical index of the cladding polymer. Acrylic-clad and plastic-clad silica fibers also show transmission losses at lower temperatures, but to lesser extents.