Publications

Caldwell, Michele C.

Abstract not provided.

Proceedings of the 2008 IEEE International Power Modulators and High Voltage Conference, PMHVC

Lehr, J.M.; Warne, Larry K.; Jorgenson, Roy E.; Wallace, Z.R.; Hodge, K.C.; Caldwell, Michele C.

It is generally acknowledged that once a highly conductive channel is established between two charged and conducting materials, electrical breakdown is well established and difficult to interrupt. An understanding of the initiation mechanism for electrical breakdown is crucial for devising mitigating methods to avoid catastrophic failures. Both volumetric and surface discharges are of interest. An effort is underway where experiments and theory are being simultaneously developed. The experiment consists of an impedance matched discharge chamber capable of investigating various gases and pressures to ten atmospheres. In addition to current and voltage measurements, a high dynamic range streak camera records streamer velocities. The streamer velocities are particularly valuable for comparison with theory. A streamer model is being developed which includes photo-ionization and particle interactions with an insulating surface. The combined theoretical and experimental effort is aimed at detailed comparisons of streamer development as well as a quantitative understanding of how streamers interact with dielectric surfaces and the resulting effects on breakdown voltage. © 2008 IEEE.

2008 IEEE International Symposium on Antennas and Propagation and USNC/URSI National Radio Science Meeting, APSURSI

Higgins, Matthew B.; Caldwell, Michele C.; Morris, Marv

Abstract not provided.

Martinez, Leonard E.; Caldwell, Michele C.

One reason to use optical fibers to transmit data is for isolation from unintended electrical energy. Using fiber optics in an application where the fiber cable/system penetrates the aperture of a grounded enclosure serves two purposes: first, it allows for control signals to be transmitted where they are required, and second, the insulating properties of the fiber system help to electrically isolate the fiber terminations on the inside of the grounded enclosure. A fundamental question is whether fiber optic cables can allow electrical energy to pass through a grounded enclosure, with a lightning strike representing an extreme but very important case. A DC test bed capable of producing voltages up to 200 kV was used to characterize electrical properties of a variety of fiber optic cable samples. Leakage current in the samples were measured with a micro-Ammeter. In addition to the leakage current measurements, samples were also tested to DC voltage breakdown. After the fiber optic cables samples were tested with DC methods, they were tested under representative lightning conditions at the Sandia Lightning Simulator (SLS). Simulated lightning currents of 30 kA and 200 kA were selected for this test series. This paper documents measurement methods and test results for DC high voltage and simulated lightning tests performed at the Sandia Lightning Simulator on fiber optic cables. The tests performed at the SLS evaluated whether electrical energy can be conducted inside or along the surface of a fiber optic cable into a grounded enclosure under representative lightning conditions.

IEEE Transactions on Electromagnetic Compatibility

Higgins, Matthew B.; Caldwell, Michele C.

Abstract not provided.

Higgins, Matthew B.; Caldwell, Michele C.

Abstract not provided.

Higgins, Matthew B.; Hudson, Howard G.; Caldwell, Michele C.

Abstract not provided.

Higgins, Matthew B.; Caldwell, Michele C.

Abstract not provided.

Caldwell, Michele C.

Abstract not provided.

Caldwell, Michele C.; Martinez, Leonard E.

Abstract not provided.

Caldwell, Michele C.; Martinez, Leonard E.

The Sandia lightning simulator at Sandia National Laboratories can provide up to 200 kA for a simulated single lightning stroke, 100 kA for a subsequent stroke, and hundreds of Amperes of continuing current. It has recently been recommissioned after a decade of inactivity and the single-stroke capability demonstrated. The simulator capabilities, basic design components, upgrades, and diagnostic capabilities are discussed in this paper.

Higgins, Matthew B.; Caldwell, Michele C.

Abstract not provided.

Caldwell, Michele C.; Martinez, Leonard E.

The Sandia Lightning Simulator at Sandia National Laboratories can provide up to 200 kA for a simulated single lightning stroke, 100 kA for a subsequent stroke, and hundreds of Amperes of continuing current. It has recently been recommissioned after a decade of inactivity and the single-stroke capability demonstrated. The simulator capabilities, basic design components, upgrades, and diagnostic capabilities are discussed in this paper.

Caldwell, Michele C.

Abstract not provided.