| 1. |
- Rahman, Mahbubur, et al.
(författare)
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Direct measurement of NOx produced by lightning
- 2006
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Ingår i: EOS Trans. AGU, 87(52), Fall Meet. Suupl., Abstract AE53A-0289, 2006, San Francisco, USA.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Rahman, Mahbubur, et al.
(författare)
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Measurements of NOx produced by rocket-triggered lightning
- 2007
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 34:3, s. L03816-
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Tidskriftsartikel (refereegranskat)abstract
- We present the first direct measurements of NOx generated by specific lightning sources. In July 2005, three negative lightning flashes were triggered using the rocket-and-wire technique at the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida. The NOx produced by these three rocket-triggered flashes was measured. The NOx production per unit charge was between 2 and 3 · 1020 molecules per meter per coulomb. The data show that the NOx production is primarily from long-duration, steady currents, as opposed to microsecondscale impulsive return stroke currents. This observation implies that cloud discharges, which transfer, via a steady current of the order of 100 A, larger charges than ground discharges, but do not contain return strokes, are as efficient as (or more efficient than) cloud-to-ground discharges in producing NOx.
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| 4. |
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| 5. |
- Akyuz, M, et al.
(författare)
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Characteristics of laser-triggered electric discharges in air
- 2005
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Ingår i: IEEE Transactions on Dielectrics and Electrical Insulation. - 1070-9878. ; 12:5, s. 1060-1070
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Tidskriftsartikel (refereegranskat)abstract
- An experiment of laser-triggered electric discharges has been conducted in a uniform background electric field. By focusing the beam of a pulsed Nd-YAG laser (wavelength 532 nm, pulse duration 5 ns) in a narrow (15 mm) plane-parallel air gap exposed to a dc voltage, streamer discharges and disruptive discharges were triggered.. The laser energy and the background electric field strength were varied in the ranges 0-180 mJ and 0.8-1.4 MV/m, respectively, and the laser plasma was induced either close to the anode, close to the cathode or mid-gap. From images of the electrode gap and from current measurements, the occurrence of and time to the streamer discharge and the disruptive discharge were determined. No distinct level was found of either the laser energy or the plasma energy for the transition from one discharge case to another, even if the general trend was that the energy required for a certain discharge case was reduced when increasing the background electric field. These and other observations make the method of laser triggering a less suitable method for studies of streamer initiation and streamer propagation, but revealed several interesting features of laser-triggered electric discharges.
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| 8. |
- Cooray, Vernon, et al.
(författare)
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On the Relationship Between the Signature of Close Electric Field and the Equivalent Corona Current in Lightning Return Stroke Models
- 2008
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Ingår i: IEEE transactions on electromagnetic compatibility (Print). - 0018-9375 .- 1558-187X. ; 50:4, s. 921-927
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Tidskriftsartikel (refereegranskat)abstract
- Engineering return stroke models can be categorized either as current generation (traveling current source type) models or current propagation (transmission line type) models. The current generation models are described among other parameters by a corona current distributed along the channel. Recent studies show that there is equivalence between the models of current generation and current propagation types. Due to this equivalence, any engineering return stroke model of current propagation type can be described in terms of an equivalent corona current per unit channel length. The measurements conducted within 10-500 m from triggered lightning Hashes show that the electric field of subsequent return strokes at these distances flattens within 15 mu s or so. In this paper, the constraints imposed by this feature on the temporal and spatial variation of the equivalent corona current are investigated. The results show that in order for the close fields to flatten within 15 mu s or so, the equivalent corona current, should be bipolar and the corona current wave shape at late times should be identical to that of the longitudinal current time derivative. This is in contrast to most of the engineering models of current generation type, in which the corona current is assumed to be unipolar.
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