HR: 0800h
AN: AE41A-0145    [Abstracts]
TI: The observation of x-ray bursts produced by 1.5 MV laboratory sparks in air
AU: Saleh, Z
EM: zsaleh@fit.edu
AF: Florida Institute of Technology, Department of Physics and Space Sciences, 150 W. University Blvd., Melbourne, FL 32901 United States
AU: * Dwyer, J R
EM: jdwyer@fit.edu
AF: Florida Institute of Technology, Department of Physics and Space Sciences, 150 W. University Blvd., Melbourne, FL 32901 United States
AU: Rassoul, H K
EM: rassoul@fit.edu
AF: Florida Institute of Technology, Department of Physics and Space Sciences, 150 W. University Blvd., Melbourne, FL 32901 United States
AU: Jerauld, J
EM: jjerauld@ufl.edu
AF: University of Florida, Department of Electrical and Computer Engineering, Gainesville, FL 32611 United States
AU: Uman, M A
EM: uman@ece.ufl.edu
AF: University of Florida, Department of Electrical and Computer Engineering, Gainesville, FL 32611 United States
AU: Plumer, J A
EM: JAPlumer@aol.com
AF: Lightning Technologies Inc., 10 Downing Industrial Parkway, Pittsfield, MA 01201 United States
AB: X-ray observations of 1.5 MV laboratory sparks were performed at the high-voltage laboratory of Lightning Technologies Inc. (LTI) in Pittsfield, MA, using the same three x-ray instruments that had been used previously for measuring x-ray emission from both rocket-triggered lightning and natural lightning at the University of Florida/Florida Tech International Center for Lightning Research and Testing (ICLRT). Observations were made during fourteen 1.5 to 2.0 m high-voltage discharges in air produced by a 1.5 MV Marx circuit. It was found that all 14 discharges generated x-rays in the ~30 to 150 keV range. The x-rays, which arrived in discrete bursts, less than 0.5 microseconds in duration, occurred from both positive and negative polarity rod-to-plane discharges as well as from small, 5 - 10 cm series spark gaps within the Marx generator. The x-ray bursts usually occurred when either the voltages across the gaps were the largest or were in the process of collapsing and were remarkably similar to the x-ray bursts previously observed from lightning. Our results imply that runaway breakdown is occurring in relatively small high-voltage sparks and that the physics of such sparks involves more than just a conventional breakdown. This finding implies that the physics used for decades to describe discharges in air may be inadequate, even for relatively small sparks. It also opens up the possibility of using laboratory sparks to study the poorly understood phenomenon of runaway breakdown. Because runaway breakdown has been shown to be associated with lightning, thunderstorms electrification and terrestrial gamma-ray flashes (TGFs) seen from space, all of which are extremely difficult to study, the laboratory study of x-rays from sparks should greatly add to our understanding of these atmospheric phenomena.
DE: 3300 ATMOSPHERIC PROCESSES
DE: 3304 Atmospheric electricity
DE: 3324 Lightning
DE: 3394 Instruments and techniques
SC: Atmospheric and Space Electricity [AE]
MN: Fall Meeting 2005