A5034556105- Lightning and Electromagnetic Phenomena
- Ionosphere and magnetosphere dynamics
- Power Line Communications and Noise
- Earthquake Detection and Analysis
- Astrophysics and Cosmic Phenomena
- High voltage insulation and dielectric phenomena
- Electrostatic Discharge in Electronics
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Advanced Optical Sensing Technologies
- Fire effects on ecosystems
- Radioactive Decay and Measurement Techniques
- Pulsed Power Technology Applications
- Atmospheric Ozone and Climate
- Planetary Science and Exploration
- Electromagnetic Compatibility and Noise Suppression
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Electrical Fault Detection and Protection
- Dark Matter and Cosmic Phenomena
- Atmospheric aerosols and clouds
- Ocular and Laser Science Research
- Nuclear Physics and Applications
- Aerosol Filtration and Electrostatic Precipitation
- Smart Grid and Power Systems
Carthage College
2013-2022
University of Bergen
2011-2021
Br. Birkeland (Norway)
2013-2021
Stanford University
2007-2010
Hewlett-Packard (United States)
2009
California Institute of Technology
2005
UC Irvine Health
1987
On the basis of RHESSI results it has been suggested that terrestrial gamma flashes (TGFs) are produced at very low altitudes. other hand some Burst and Transient Source Experiment (BATSE) spectra show unabsorbed fluxes X rays in 25–50 keV energy range, indicating a higher production altitude. To investigate this, we have developed Monte Carlo code for X‐ray propagation through atmosphere. The most important features seen modeled (1) low‐energy cutoff which moves to lower energies as TGFs...
Terrestrial gamma‐ray flash (TGF) production has been modeled by several emission mechanisms. In spite of extensive studies these mechanisms and the existing satellite data, significant uncertainties exist about nature source. this paper, we present a method to develop approximate production‐mechanism‐independent constraints on TGF basis Monte Carlo simulation propagation through atmosphere. A broad range possible source parameters are simulated, based assumptions simplified with varying...
The production of terrestrial gamma ray flashes (TGFs) requires a seed energetic electron source and strong electric field. Lightning leaders naturally provide electrons by cold runaway fields charge accumulation on the channel. We model possible TGF in such simulating charges currents resulting then drive simulations relativistic avalanche photon emission. Photon spectra directional distributions produced agree qualitatively with observations. Simulations variety initial conditions indicate...
We present the very first simultaneous detection from space of a terrestrial gamma ray flash (TGF) and optical signal lightning. By fortuitous coincidence, two independent satellites passed less than 300 km thunderstorm system that produced TGF lasted 70 μ s. Together with measurements radio emissions, we have an unprecedented coverage event. find was deep in thundercloud at initial stage intracloud (IC) lightning before leader reached cloud top extended horizontally. A strong pulse by...
In this paper we use the fluence distributions observed by two different instruments, RHESSI and Fermi GBM, corrected for effects of their orbits, combined with daily TGF detection rates relative sensitivities to make an estimate true distribution TGFs as measured at satellite altitudes. The is then used calculate dead‐time loss average RHESSI. An independent obtained from a Monte Carlo (MC) simulation in order evaluate consistency our results. methods give losses 24–26% 33–35 counts....
Terrestrial gamma ray flashes (TGFs) are brief bursts of rays observed by satellites, typically in coincidence with detectable lightning. We incorporate TGF observations and the key physics behind current production theories lightning to produce constraints on mechanisms. The combined naturally suggest a mechanism for pulses leader channels. involves local field enhancements due charge redistribution draws seed energetic particles from cold runaway breakdown processes. can reproduce time...
Terrestrial gamma ray flashes (TGFs) are brief bursts of photons with energies up to 20 MeV typically observed in association lightning. Such energetic may undergo photonuclear reactions nontrivial cross section the vicinity giant dipole resonance. Pulses neutrons have been experimentally coincidence lightning, suggesting such observable. We present simulations expected photoneutron production based on initial conditions inferred from observations TGFs. predict an average ∼10 12 produced per...
[1] Terrestrial gamma ray flashes (TGFs) are bremsstrahlung emissions from relativistic electrons accelerated in electric fields associated with thunder storms, photon energies up to at least 40 MeV, which sets the lowest estimate of total potential MV. The field that produces TGFs will be reflected by initial angular distribution TGF emission. Here we present first constraints on emission cone based accurately geolocated TGFs. source lightning discharges detected RHESSI determined...
This letter presents a new search algorithm for identifying Terrestrial Gamma ray Flashes (TGFs) in the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) data. The has been applied to data from period 2004–2006 and we have found more than twice as many TGFs previously reported. follow same geographical seasonal variations reported TGFs. match percentage between World Wide Lightning Location Network (WWLLN) is comparable RHESSI catalog Our results shows that previous searches only...
Abstract This paper presents the first study that uses GEometry ANd Tracking 4 (GEANT4) toolkit to do quantitative comparisons with other modeling results related production of terrestrial gamma ray flashes and high‐energy particle emission from thunderstorms. We will relativistic runaway electron avalanche (RREA) feedback process, as well bremsstrahlung photons electrons. The Monte Carlo simulations take into account effects ionization, by (Møller), positron (Bhabha) scattering process pair...
The Modular X- and Gamma-ray Sensor (MXGS) is an imaging spectral instrument mounted on the starboard side of Columbus module International Space Station. Together with Multi-Spectral Imaging Assembly (MMIA) (Chanrion et al. this issue) MXGS constitutes instruments Atmosphere-Space Interactions Monitor (ASIM) (Neubert issue). main objectives are to image measure spectrum $\gamma $ -rays from lightning discharges, known as Terrestrial Flashes (TGFs), for MMIA perform high speed photometry...
During the return stroke in downward negative cloud-to-ground lightning, a current wave propagates upward from ground along lightning channel. The causes rapid heating of channel and induces intense optical radiation. radiation propagation speed has been measured to be between light. is commonly assumed same but cannot directly measured. Past modeling efforts treat either thermodynamics or electrodynamics. We present first model that simultaneously treats coupled thermodynamic physics...
Relativistic runaway electron avalanches (RREAs) occur when relativistic electrons undergo avalanche multiplication driven by electric fields. The RRE has been studied extensively, but existing results typically assume a rudimentary source of seed electrons. Here we focus on the seeding process and simulate effective efficiencies for various particle types, energies, geometries. Including known from cosmic ray physics, calculate total distributions their statistical fluctuations use...
[1] Terrestrial gamma-ray flashes (TGFs) are associated with emission of detectable beams electrons into space. In this paper we use simulations TGF and electron beam escape from the atmosphere to determine how geometry fluence such events depend on angular distribution source photons. Given a photon source, depends geomagnetic latitude but can be well-predicted by tracing disk at 57 km altitude along field satellite orbit. The then used infer relative detection probabilities in context...
Abstract Several computer models exist to explain the observation of terrestrial gamma‐ray flashes (TGFs). Some these estimate electric field ahead lightning leaders and its effects on electron acceleration multiplication. In this paper, we derive a new set constraints do more realistic modeling. We determine initial conditions based in situ measurements vertical separation between main charge layers thunderclouds. A maximum strength 50 kV/cm at sea level is introduced as upper constraint...
Abstract The Atmosphere‐Space Interactions Monitor (ASIM) is the first instrument in space specifically designed to observe terrestrial gamma‐ray flashes (TGFs). TGFs are high energy photons associated with lightning and we perform spectral analysis of 17 detected by ASIM. TGF sample carefully selected rigorous selection criteria keep a clean suitable for analysis, that is, count statistics, low instrumental effects, reliable source location. Monte Carlo modeling individual has been compared...
Discharge experiments were carried out at the Eindhoven University of Technology in 2013. The experimental setup was designed to search for electrons produced meter-scale sparks using a 1 MV Marx generator. Negative voltage applied high (HV) electrode. Five thin (1 mm) plastic detectors (5 $\rm cm^2$ each) distributed various configurations close spark gap. Earlier studies have shown (for HV negative) that X-rays are when cloud streamers is developed 30-60 cm from negative This indicates...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation B. E. Carlson, N. G. Lehtinen, U. S. Inan; Observations of Terrestrial Gamma‐Ray Flash Electrons. AIP Conf. Proc. 27 April 2009; 1118 (1): 84–91. https://doi.org/10.1063/1.3137717 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search...
Up to a few years ago, terrestrial gamma ray flashes (TGFs) were only observed by spaceborne instruments. The aircraft campaign ADELE was able observe one TGF, and more attempts on observations are planned. There is also planned with stratospheric balloons, COBRAT. In this context an important question that arises what count rates we can expect how these estimates affected the initial properties of TGFs. Based simulations photon propagation in air find fluence at different observation points...
X-ray emission by sparks implies bremsstrahlung from a population of energetic electrons, but the details this process remain mystery. We present detailed statistical analysis spectra detected multiple detectors during produced 1 MV negative high-voltage pulses with $\mu$s risetime. With over 900 shots, we statistically analyze signals, assuming that distribution spark fluence behaves as power law and energy spectrum X-rays detectable after traversing $\sim$2 m air thin aluminum shield is...
Abstract We report the first Terrestrial Electron Beam detected by Atmosphere‐Space Interactions Monitor. It happened on 16 September 2018. The Monitor Modular X and Gamma ray Sensor recorded a 2 ms long event, with softer spectrum than typically for Flashes (TGFs). lightning discharge associated to this event was found in World Wide Lightning Location Network data, close northern footpoint of magnetic field line that intercepts International Space Station location. Imaging from GOES‐R...
Abstract Terrestrial Gamma ray Flashes (TGFs) are short flashes of high energy photons, produced by thunderstorms. When interacting with the atmosphere, they produce relativistic electrons and positrons, a part gets bounded to geomagnetic field lines travels large distances in space. This phenomenon is called Electron Beam (TEB). The Atmosphere‐Space Interactions Monitor (ASIM) mounted on‐board International Space Station detected new TEB event on March 24, 2019, originating from tropical...
Terrestrial gamma‐ray flashes (TGFs) as observed by satellites have a broad fluence distribution. This distribution is not trivially related to the source strength distribution, since even very strong TGF may still be at low if far from satellite. In this paper we connect with calculating effective size and probability of detection TGFs function their strength. For sources single altitude, power law distributions give softer in especially pronounced softening for hard indices. result holds...
Lightning discharge is a complicated process with relevant physical scales spanning many orders of magnitude. In an effort to understand the electrodynamics lightning and connect properties channel observed behavior, we construct simulation charge current flow on narrow conducting embedded in three-dimensional space time domain electric field integral equation, method moments, thin-wire approximation. The includes approximate treatment resistance evolution due heating corona sheath...
We present the results of a search for time correlations in high energy cosmic ray data (primary E > 10^14 eV) collected by California HIgh school Cosmic ObServatory (CHICOS) array. Data from 69 detector sites spread over an area 400 km^2 were studied evidence isolated events separated more than 1 km with coincidence times ranging microseconds up to second. report upper limits probability as function time.