Naval Surface Warfare Center

About: Naval Surface Warfare Center is a facility organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Sonar & Radar. The organization has 2855 authors who have published 3697 publications receiving 83518 citations. The organization is also known as: NSWC.

Investigation on the reaction of iron powder mixture as a portable heat source for thermoelectric power generators

Abstract: This paper reports our investigation on the thermal behavior and ignition characteristics of iron powder and mixtures of iron with other materials such as activated carbon and sodium chloride in which iron is the main ingredient used as fuel. Thermal analysis techniques such as differential scanning calorimetry (DSC) and thermogravimetric analysis were used to characterize the materials and for further understanding of reaction kinetics of the pyrophoric iron mixtures. The experimental results demonstrated that iron micron particles react exothermically to the oxygen in atmosphere and produced iron oxide with ignition temperature of 427.87 °C and heat generation of 4,844 J g−1. However, in this study, the pyrophoric iron mixture acts as a heat source for the thermoelectric power generators, the final mixture composition is determined to compose of iron powder, activated carbon, and sodium chloride with the mass ratio of approximately 5/1/1. The mixture generated two exothermic peaks DSC curves that showed ignition temperature of 431.53 and 554.85 °C and with a higher heat generation of 9,366 J g−1 at higher temperature. The effects of test pan materials and heating rate on the ignition were also examined by DSC method. Kinetic data such as the activation energy (Ea), the entropy of activation (ΔS#), enthalpy of activation (ΔH#), and Gibbs energy of activation (ΔG#) on the ignition processes was also derived from the DSC analysis. From the ignition temperature, heat generation, and kinetics test data, the mass ratio of 5/1/1 proved to generate the most amount of heat with high temperatures for the standalone thermoelectric power generators.

Radiation-induced base current broadening mechanisms in gated bipolar devices

Abstract: Ionizing radiation experiments on gated lateral bipolar junction transistors (BJTs) show a broadening in the peak base current profile after irradiation. The primary mechanism for this effect is identified as the change in the charge state of interface traps in the oxide over the base. Simulations and theoretical analysis not only describe the mechanism in detail, but also suggest possible solutions for extracting information from the shape of the profile. The effects of the interface-trap energy distribution are investigated, showing that traps between flatband and threshold contribute to the width of the base-current peak.