Electrical structure of the thundercloud and operation of the electron accelerator inside it

Chilingarian, A.; Hovsepyan, G.; Svechnikova, Ekaterina; Zazyan, M.

doi:10.1016/j.astropartphys.2021.102615

Cited by 27 publications

(30 citation statements)

References 23 publications

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“…No events were tabulated with increases less than 1% and so this value can be taken as a noise floor. In exceptional TGEs with count rate increases larger by an order of magnitude and more, and with detectable energetic electrons in more recent studies (Chilingarian, Hovsepyan, Svechnikova, & Zazyan 2021;, the energetic electron counts at the ground are of the order of 10% of the gamma ray counts. On this basis, it may be inferred that the variation in the energetic electron population will be approximately 10% of 3%, or 0.3%.…”

Section: Surface Detectability Of Energetic Electrons In Tgesmentioning

confidence: 94%

“…Estimates of this quantity vary widely. In the nuclear physics literature on TGEs, the free passage distance is often associated with the cloud base height Chilingarian, 2018aChilingarian, , 2018bChilingarian, Hovsepyan, Svechnikova, & Zazyan, 2021) which for the Aragats station (3.2 km MSL) is often 100m or less.…”

Section: Surface Detectability Of Energetic Electrons In Tgesmentioning

confidence: 99%

“…They have been shown to occur in the presence of exceptional magnitudes of the electric field. From the earliest searches for runaway electrons (Schonland, 1930; Wilson, 1929) to today (Chilingarian, Hovsepyan, Svechnikova, & Zazyan, 2021), the main negative charge of the thunderstorm has served as the repulsive accelerator of electrons, downward below it and upward above it (Wilson, 1929; see also Figure 1). Ironically, the key “enhancement” in TGEs at the ground (in addition to the magnitude of the electric field) is the downward gamma radiation Wilson had de‐emphasized and produced by the bremsstrahlung from the accelerated electrons in the avalanche region beneath the main negative charge (Chilingarian, Hovsepyan, Svechnikova, & Zazyan, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…From the earliest searches for runaway electrons (Schonland, 1930;Wilson, 1929) to today (Chilingarian, Hovsepyan, Svechnikova, & Zazyan, 2021), the main negative charge of the thunderstorm has served as the repulsive accelerator of electrons, downward below it and upward above it (Wilson, 1929; see also Figure 1). Ironically, the key "enhancement" in TGEs at the ground (in addition to the magnitude of the electric field) is the downward gamma radiation Wilson had de-emphasized and produced by the bremsstrahlung from the accelerated electrons in the avalanche region beneath the main negative charge (Chilingarian, Hovsepyan, Svechnikova, & Zazyan, 2021). The range of gamma rays in the air is an order of magnitude larger than that of electrons of the same energy (Evans, 1955), and so the gamma rays can serve as a messenger for electron acceleration for the breakdown field higher in the storm.TGEs have now been documented at elevated observatories worldwide in summer, and at sea level in winter when the strong field region is substantially closer to the surface observations (e.g., Torii et al, 2011;Wada et al, 2021).…”

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confidence: 99%

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Radar Diagnosis of the Thundercloud Electron Accelerator

et al. 2022

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Thunderstorm Ground Enhancements (TGEs) refer to correlated enhancements in surface electric field and gamma ray flux that are manifestations of electron runaway in the storm overhead. The electric field enhancements can be of positive or negative polarity. In this study, altitude‐resolved S‐band radar observations of graupel are used to demonstrate distinct differences in storm structure linked with these “positive” and “negative” TGEs. The physical interpretation rests on the well‐established temperature‐dependent tripole structure of thunderstorms, with the main negative charge of the tripole acting as an electron repeller. This interpretation is supported by case studies showing altitude‐stable convection, with shallow (deep) development linked with “positive” (“negative”) TGEs, and by case studies of collapsing storms that show upper dipole dominance early and lower inverted dipole dominance later when graupel particles descend from a colder to warmer temperature domain. In the case of many TGEs on Mt Aragats (3.2 km MSL), the temperature‐dependent altitude of downward electron acceleration and avalanching may be sufficiently distant (>500 m) from surface detectors that the energetic electrons (1–10 MeV) are not likely avalanche/runaway electrons. Instead, they are Compton‐scattered and pair‐produced electrons from bremsstrahlung gamma radiation emanating from the high‐field avalanche region aloft. These inferences are consistent with GEANT4 calculations that identify the physical origins of energetic electrons at the surface.

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Section: Surface Detectability Of Energetic Electrons In Tgesmentioning

confidence: 94%

Section: Surface Detectability Of Energetic Electrons In Tgesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Radar Diagnosis of the Thundercloud Electron Accelerator

et al. 2022

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“…In the second scenario, both emerged electric fields have the same direction inside the cloud and can boost overall potential drop and lead to more intense TGE flux and larger maximum energy of the TGE electrons. As the electrons are very fast attenuated in the atmosphere after leaving the accelerating field, by comparison of the maximum energies of gamma ray and electron spectra we can estimate the height where the electric field declines (see Figure 9 in Chilingarian et al (2021b)). The electric field induced by the dipole formed by the main negative layer and its mirror in the Earth (MN-MIRR) can extend down very low (25-100 m) above the Earth's surface.…”

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confidence: 99%

Muon Tomography of Charged Structures in the Atmospheric Electric Field

Chilingarian

Hovsepyan

Zazyan

2021

Geophysical Research Letters

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The electric field in the lower part of the thundercloud plays a key role in developing the relativistic runaway electron avalanches (RREAs), which reaching and are registered on the Earth's surface as thunderstorm ground enhancements (TGEs). Different species of cosmic rays, which include electrons, positrons, muons, gamma rays, and neutrons, were directly or nondirectly modulated by the intracloud electric field and comprise multisensory messengers bringing information on the electric fields emerging in the thundercloud. Recently, we used the measurements of the near-surface (NS) electric field, the graupel fall, and the energy spectra of electrons and gamma rays to get insight into the charge structure of the lower dipole and to estimate the maximum electric field in the thundercloud (Chilingarian et al., 2021a(Chilingarian et al., , 2021c. We considered the depletion of the muon flux as an evidence of a large negative electric field in the lower part of the thundercloud, which accelerates electrons downward and initiates electron-gamma ray avalanches. As a basic configuration of the thundercloud charge structure, we accept a classical tripole (Kuettner, 1950). For a normal three-layered tripole, the lower positively charged region (LPCR) has a smaller size and smaller charge than the upper main layers, negatively (MN) and positively charged (MP). However, alternative charge configurations were reported (see Rust et al., 2005, and references therein) inverted polarity dipole (Nag & Rakov, 2012), i.e., charge regions having a positive charge above the negative one in the vertical distribution of charge. Such structures are rare and rather difficult to identify. In the famous work (Nag & Rakov, 2009), authors conclude that the occurrence of pronounced preliminary breakdown (PB) pulse train proves the existence of an unusually large LPCR.We outline two main scenarios (Chilingarian et al., 2020) supporting the origination of the large fluxes of electrons and gamma rays measured by the particle detectors and spectrometers located on the mountain altitudes. The first one is related to the large main negative charge above the detectors site at an altitude of

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Charge distribution in the thundercloud, electron acceleration, and lightning initiation

Chilingarian¹,

Hovsepyan²

2021

Preprint

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Electrical structure of the thundercloud and operation of the electron accelerator inside it

Cited by 27 publications

References 23 publications

Radar Diagnosis of the Thundercloud Electron Accelerator

Radar Diagnosis of the Thundercloud Electron Accelerator

Muon Tomography of Charged Structures in the Atmospheric Electric Field

Charge distribution in the thundercloud, electron acceleration, and lightning initiation

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