Properties of the X‐ray emission from rocket‐triggered lightning as measured by the Thunderstorm Energetic Radiation Array (TERA)

Saleh, Z.; Dwyer, J. R.; Howard, Joseph; Uman, M. A.; Bakhtiari, M.; Concha, D.; Stapleton, M. V.; Hill, Dustin; Biagi, C. J.; Rassoul, H. K.

doi:10.1029/2008jd011618

Cited by 65 publications

(170 citation statements)

References 44 publications

Supporting

Mentioning

165

Contrasting

Order By: Relevance

“…The Monte Carlo code used in this work was developed at Florida Tech in 2002 by J. R. Dwyer [ Dwyer , 2003, 2004, 2005, 2007, 2008, 2009, 2010; Coleman and Dwyer , 2006; Saleh et al , 2009; Dwyer et al , 2009; Dwyer and Babich , 2011]. This Monte Carlo simulation of relativistic runaway electron avalanches is capable of modeling the development and propagation of runaway electron avalanches in any gaseous medium for both spatially and time‐varying electric and magnetic fields.…”

Section: Monte Carlo Simulationsmentioning

confidence: 99%

“…Indeed, X‐rays are now routinely measured from natural cloud‐to‐ground and rocket‐and‐wire‐triggered lightning. In a series of experiments beginning in 2002 at the University of Florida/Florida Tech International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, FL, it was found that lightning produces significant X‐ray emission up to about an MeV during the stepped‐leader phase of natural lightning and during the dart‐leader phase of natural and rocket‐and‐wire‐triggered lightning, with the most intense emission often detected immediately before the return stroke during the attachment process [ Dwyer et al , 2004b, 2005; Howard et al , 2008; Saleh et al , 2009; Howard et al , 2010]. The X‐rays are usually observed to arrive in short (<1 μ s) bursts in coincidence with the step formation of the stepped leaders and dart‐stepped leaders.…”

Section: Cold Runaway Electron Simulationsmentioning

confidence: 99%

“…Using the luminosity of runaway electrons measured from triggered lightning of about 10 17 electrons per second [ Saleh et al , 2009], with an additional RREA multiplication of 10 4 (consistent with the feedback limit), in 10 −4 s (the duration of a TGF) 10 17 runaway electrons would result, with the correct 7 MeV energy spectrum [ Dwyer et al , 2010]. However, it is not clear how the TGF time scale of 0.1 ms comes about.…”

Section: Cold Runaway Electron Simulationsmentioning

confidence: 99%

See 2 more Smart Citations

The relativistic feedback discharge model of terrestrial gamma ray flashes

2012

View full text Add to dashboard Cite

.[1] As thunderclouds charge, the large-scale fields may approach the relativistic feedback threshold, above which the production of relativistic runaway electron avalanches becomes self-sustaining through the generation of backward propagating runaway positrons and backscattered X-rays. Positive intracloud (IC) lightning may force the large-scale electric fields inside thunderclouds above the relativistic feedback threshold, causing the number of runaway electrons, and the resulting X-ray and gamma ray emission, to grow exponentially, producing very large fluxes of energetic radiation. As the flux of runaway electrons increases, ionization eventually causes the electric field to discharge, bringing the field below the relativistic feedback threshold again and reducing the flux of runaway electrons. These processes are investigated with a new model that includes the production, propagation, diffusion, and avalanche multiplication of runaway electrons; the production and propagation of X-rays and gamma rays; and the production, propagation, and annihilation of runaway positrons. In this model, referred to as the relativistic feedback discharge model, the large-scale electric fields are calculated self-consistently from the charge motion of the drifting low-energy electrons and ions, produced from the ionization of air by the runaway electrons, including two-and three-body attachment and recombination. Simulation results show that when relativistic feedback is considered, bright gamma ray flashes are a natural consequence of upward +IC lightning propagating in large-scale thundercloud fields. Furthermore, these flashes have the same time structures, including both single and multiple pulses, intensities, angular distributions, current moments, and energy spectra as terrestrial gamma ray flashes, and produce large current moments that should be observable in radio waves.

show abstract

Section: Monte Carlo Simulationsmentioning

confidence: 99%

Section: Cold Runaway Electron Simulationsmentioning

confidence: 99%

Section: Cold Runaway Electron Simulationsmentioning

confidence: 99%

See 1 more Smart Citation

The relativistic feedback discharge model of terrestrial gamma ray flashes

2012

View full text Add to dashboard Cite

show abstract

“…X-ray emissions have been measured successfully over a span of about ten years from triggered lightning and natural lightning in Florida at distances up to about a kilometre from the lightning channel [16][17][18][19]. According to experiments carried out in Gainesville, Florida, the maximum source height of X-rays corresponding to first-stroke stepped leaders and dart-stepped leaders of natural lightning are 800 m and 3.6 km respectively [19].…”

Section: Discussionmentioning

confidence: 99%

“…The detector used is similar to the detector described in more detail in [18] by Saleh et al Two fibre-optic links (of type Terahertz Technologies V-250, with a bandwidth of 10 MHz, and input voltage peak-to-peak threshold of 1 V) carried the detector signal to a transient recorder inside the EMC cabinet. The X-ray detection system (the detectors and fibre-optic transmitters) was powered by two 12 V batteries also housed inside the same aluminium box as the detectors.…”

Section: Methodsmentioning

confidence: 99%

X-ray Observations at Gaisberg Tower

et al. 2018

View full text Add to dashboard Cite

Abstract:We report the occurrence of X-rays at ground level due to cloud-to-ground flashes of upward-initiated lightning from Gaisberg Tower, in Austria, which is located at an altitude of 1300 m. This is the first observation of X-ray emissions from upward lightning from a tower top located at high altitude. Measurements were carried out using scintillation detectors installed close to the tower top in two phases from 2011 to 2015. X-rays were recorded in three subsequent strokes of three flashes out of the total of 108 flashes recorded in the system during both phases. In contrast to the observations from downward natural or triggered lightning, X-rays were observed only within 10 µs before the subsequent return stroke. This shows that X-rays were emitted when the dart leader was in the vicinity of the tower top, hence during the most intense phase of the dart leader. Both the detected energy and the fluence of X-rays are far lower compared to X-rays from downward natural or rocket-triggered lightning. In addition to the above 108 flashes, an interesting observation of X-rays produced by a nearby downward flash is also presented. The shorter length of dart-leader channels in Gaisberg is suggested as a possible cause of this apparently weaker X-ray production.

show abstract

The angular distribution of energetic electron and X‐ray emissions from triggered lightning leaders

et al. 2013

View full text Add to dashboard Cite

[1] We investigate individual X-ray bursts from lightning leaders to determine if energetic electrons at the source (and hence X-rays) are emitted isotropically or with some degree of anisotropy. This study was motivated by the work of Saleh et al. (2009), which found the falloff of X-rays in concentric radial annuli, covering all azimuthal directions in each annulus, from the lightning channel to be most consistent with an isotropic electron source. Here we perform a statistical analysis of angular and spatial distributions of X-rays measured by up to 21 NaI/PMT detectors at the International Center for Lightning Research and Testing site for 21 leader X-ray bursts from five leaders (including four dart-stepped leaders and one dart leader). Two procedures were used to complete this analysis. Procedure 1 found the first-order anisotropy, and procedure 2 tested whether or not the angular distribution was consistent with an isotropic distribution. Because higher-order anisotropies could be present in the data, a distribution that is not isotropic does not necessarily have a significant first-order anisotropy. Using these procedures, we find that at least 11 out of 21 X-ray bursts have a statistically significant first-order anisotropy, and hence those 11 are inconsistent with an isotropic emission. The remaining 10 bursts do not have significant first-order anisotropy. However, of those 10 bursts, 9 are inconsistent with isotropic emission, since they exhibit significant higher-order anisotropies. Since Saleh et al. (2009) did not consider anisotropies in the azimuthal direction, these new measurements of anisotropy do not necessarily contradict that work. Indeed, our analysis supports the finding that the X-ray emissions from lightning are inconsistent with a vertically downward beam. The level of anisotropy of the runaway electrons is important because it provides, in principle, information on the streamer zone in front of the leader and the electric field near the lightning leader tip.

show abstract

Properties of the X‐ray emission from rocket‐triggered lightning as measured by the Thunderstorm Energetic Radiation Array (TERA)

Cited by 65 publications

References 44 publications

The relativistic feedback discharge model of terrestrial gamma ray flashes

The relativistic feedback discharge model of terrestrial gamma ray flashes

X-ray Observations at Gaisberg Tower

The angular distribution of energetic electron and X‐ray emissions from triggered lightning leaders

Contact Info

Product

Resources

About