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A ceramic material having a large dielectric constant at 77 K, ε=8000-12000, has been developed for capacitive energy storage at this temperature. A large matrix of multilayer ceramic capacitors were fabricated using conventional tape-casting methods to optimize the dielectric breakdown strength at 77 K, and measured energy storage values on these capacitors range up to 6 J/cm3 at 77 K. An unfused bank of these capacitors was voltage-cycled 105 times at 77 K without failure, and the heating effects during cycling were immeasurably small (i.e., nitrogen boiloff was monitored). An electrocaloric effect on discharge (ΔT~1 K) contributes to the thermal stability. Measurements of the frequency dependence of the dielectric properties of the ceramic at 77 K indicate a fundamental limit of about 8 μs for the switching repetition rate. Improved capacitor-manufacturing methods are discussed which can increase the energy density to the 20-30 J/cm3 range 相似文献
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A. Banin J.G. Lawless R.C. Whitten 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(12):207-216
Tropospheric nitrous oxide concentration has increased by 0.2 – 0.4% per year over the period 1975 to 1982, amounting to net addition to the atmosphere of 2.8 – 5.6 Tg N2O-N per year. This perturbation, if continued into the future, will affect stratospheric chemical cycles, and the thermal balance of the Earth. In turn it will have direct and indirect global effects on the biosphere. Though the budget and cycles of N2O on Earth are not yet fully resolved, accumulating information and recent modelling efforts enable a more complete evaluation and better definition of gaps in our knowledge. 相似文献
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