A second-order differential equation for the fast wave propagating in a hot, two-ion species plasma is obtained. This second-order approximation is obtained unambiguously and allows the wave amplitude to be identified with one of the electric field components. The approximation is based on replacing the coupling to the ion-Bernstein wave by a localized perturbation of the fast wave. For the case of perpendicular propagation, the second-order equation reduces to Budden’s equation giving the well-known transmission coefficient for both two-ion hybrid and second-harmonic resonance. The equation includes the effect of simultaneous minority fundamental and majority second-harmonic cyclotron damping. The solutions of the second-order equation as a function of n∥ give absorption transmission and reflection coefficients that agree well with the results based on models giving higher-order differential equations and solved by means of much more complex numerical codes.
The U.S. Navy made a major step forward in the protection of switchgear from arcing faults with the installation of arc fault detection systems beginning in 1990. These systems have a proven history of responding to arcs quickly enough to minimize damage and have reliability high enough to be certified for use in nuclear reactor power systems. However, all damage is not eliminated and loss of power never occurs at a convenient time. The predominant cause of arcing failures in Navy switchboards has been identified. Test data that confirms how these failures develop will be discussed. A low-cost sensor has been designed that will allow the detection of the majority of impending arcing failures by performing continuous thermal monitoring of the switchboard. A single detector can determine if a connection within the switchboard has exceeded 300 C, which is well below the 1083 C needed to melt copper. The operator is notified upon the detection of an impending failure and corrective action can be taken before arcing occurs. Details of the development of the sensor will be discussed.
Common sub-millimeter particle impact phenomena range from zero to thousands of joules of impact energy. The physics of impacts are associated with a wide variety of physical phenomena, including the generation of heat, light, and sound. Although higher energy impact events may result in vaporization of the impacted material and other easily detectable effects, lower energy level impacts of interest may occur with little obvious physical effect. Preliminary research with capacitative sensors provided encouraging results for detecting low-energy impacts. However, vibration within the sensor mounting structure interfered with the detection of impact events. Research on triboluminescent phosphors indicated that a thin layer of material could be used to form the basis of an optical sensor to detect small particle impacts without interference from structural vibrations. A ZnS:Mn phosphor was used as the basis for developing a triboluminescent fiber optic sensor to detect small particle impact events. Detection of impacts is accomplished by detecting the optical pulse that is generated by the abrupt charge separation caused by the particle impact within the phosphor. Laboratory-based experiments were performed to capture the operational characteristics of the sensor. The data are used to study the characteristic response, sensor repeatability, and spatial homogeneity of the detection surface. Tests were also performed to identify the energy detection boundary and to assess environmental survivability. Results of these tests are reported in this paper.
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