Influence of the angular scattering of electrons on the runaway
threshold in air

J 2016

Influence of the angular scattering of electrons on the runaway threshold in air

CHANRION, Olivier, Zdeněk BONAVENTURA, Anne BOURDON and Torsten NEUBERT

Basic information

Original name

Influence of the angular scattering of electrons on the runaway threshold in air

Name in Czech

Vliv úhlového rozptylu elektronů na práh pro ubíhající elektrony

Authors

CHANRION, Olivier (250 France), Zdeněk BONAVENTURA (203 Czech Republic, guarantor, belonging to the institution), Anne BOURDON (250 France) and Torsten NEUBERT (208 Denmark)

Edition

Plasma Physics and Controlled Fusion, Institute of Physics, 2016, 0741-3335

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

10305 Fluids and plasma physics

Country of publisher

United Kingdom of Great Britain and Northern Ireland

Confidentiality degree

není předmětem státního či obchodního tajemství

References:

URL

Impact factor

Impact factor: 2.392

RIV identification code

RIV/00216224:14310/16:00087786

Organization unit

Faculty of Science

DOI

http://dx.doi.org/10.1088/0741-3335/58/4/044001

UT WoS

000371818600004

Keywords in English

terrestrial gamma-ray flashes; runaway electrons; streamers; thunderstorms; angular scattering; lightning; thermal runaway

Abstract

V originále

The runaway electron mechanism is of great importance for the understanding of the generation of x- and gamma rays in atmospheric discharges. In 1991, terrestrial gamma-ray flashes (TGFs) were discovered by the Compton Gamma-Ray Observatory. Those emissions are bremsstrahlung from high energy electrons that run away in electric fields associated with thunderstorms. In this paper, we discuss the runaway threshold definition with a particular interest in the influence of the angular scattering for electron energy close to the threshold. In order to understand the mechanism of runaway, we compare the outcome of different Fokker–Planck and Monte Carlo models with increasing complexity in the description of the scattering. The results show that the inclusion of the stochastic nature of collisions smooths the probability to run away around the threshold. Furthermore, we observe that a significant number of electrons diffuse out of the runaway regime when we take into account the diffusion in angle due to the scattering. Those results suggest using a runaway threshold energy based on the Fokker–Planck model assuming the angular equilibrium that is 1.6 to 1.8 times higher than the one proposed by [1, 2], depending on the magnitude of the ambient electric field. The threshold also is found to be 5 to 26 times higher than the one assuming forward scattering. We give a fitted formula for the threshold field valid over a large range of electric fields. Furthermore, we have shown that the assumption of forward scattering is not valid below 1 MeV where the runaway threshold usually is defined. These results are important for the thermal runaway and the runaway electron avalanche discharge mechanisms suggested to participate in the TGF generation.

Links

GA15-04023S, research and development project

Name: Pokročilý výzkum kinetických procesů ve streamerových výbojích

Investor: Czech Science Foundation

LO1411, research and development project

Name: Rozvoj centra pro nízkonákladové plazmové a nanotechnologické povrchové úpravy (Acronym: CEPLANT plus)

Investor: Ministry of Education, Youth and Sports of the CR

Citovat

CHANRION, Olivier, Zdeněk BONAVENTURA, Anne BOURDON and Torsten NEUBERT. Influence of the angular scattering of electrons on the runaway threshold in air. Plasma Physics and Controlled Fusion. Institute of Physics, 2016, vol. 58, No 4, p. "nestrankovano", 9 pp. ISSN 0741-3335. Available from: https://dx.doi.org/10.1088/0741-3335/58/4/044001.

@article{1331616,
   author = {Chanrion, Olivier and Bonaventura, Zdeněk and Bourdon, Anne and Neubert, Torsten},
   article_number = {4},
   doi = {http://dx.doi.org/10.1088/0741-3335/58/4/044001},
   keywords = {terrestrial gamma-ray flashes; runaway electrons; streamers; thunderstorms; angular scattering; lightning; thermal runaway},
   language = {eng},
   issn = {0741-3335},
   journal = {Plasma Physics and Controlled Fusion},
   title = {Influence of the angular scattering of electrons on the runaway threshold in air},
   url = {http://iopscience.iop.org/article/10.1088/0741-3335/58/4/044001},
   volume = {58},
   year = {2016}
}

TY  - JOUR
ID  - 1331616
AU  - Chanrion, Olivier - Bonaventura, Zdeněk - Bourdon, Anne - Neubert, Torsten
PY  - 2016
TI  - Influence of the angular scattering of electrons on the runaway threshold in air
JF  - Plasma Physics and Controlled Fusion
VL  - 58
IS  - 4
SP  - "nestrankovano"
EP  - "nestrankovano"
PB  - Institute of Physics
SN  - 07413335
KW  - terrestrial gamma-ray flashes
KW  - runaway electrons
KW  - streamers
KW  - thunderstorms
KW  - angular scattering
KW  - lightning
KW  - thermal runaway
UR  - http://iopscience.iop.org/article/10.1088/0741-3335/58/4/044001
L2  - http://iopscience.iop.org/article/10.1088/0741-3335/58/4/044001
N2  - The runaway electron mechanism is of great importance for the understanding of the generation of x- and gamma rays in atmospheric discharges. In 1991, terrestrial gamma-ray flashes (TGFs) were discovered by the Compton Gamma-Ray Observatory. Those emissions are bremsstrahlung from high energy electrons that run away in electric fields associated with thunderstorms. In this paper, we discuss the runaway threshold definition with a particular interest in the influence of the angular scattering for electron energy close to the threshold. In order to understand the mechanism of runaway, we compare the outcome of different Fokker–Planck and Monte Carlo models with increasing complexity in the description of the scattering. The results show that the inclusion of the stochastic nature of collisions smooths the probability to run away around the threshold. Furthermore, we observe that a significant number of electrons diffuse out of the runaway regime when we take into account the diffusion in angle due to the scattering. Those results suggest using a runaway threshold energy based on the Fokker–Planck model assuming the angular equilibrium that is 1.6 to 1.8 times higher than the one proposed by [1, 2], depending on the magnitude of the ambient electric field. The threshold also is found to be 5 to 26 times higher than the one assuming forward scattering. We give a fitted formula for the threshold field valid over a large range of electric fields. Furthermore, we have shown that the assumption of forward scattering is not valid below 1 MeV where the runaway threshold usually is defined. These results are important for the thermal runaway and the runaway electron avalanche discharge mechanisms suggested to participate in the TGF generation.
ER  -

CHANRION, Olivier, Zdeněk BONAVENTURA, Anne BOURDON and Torsten NEUBERT. Influence of the angular scattering of electrons on the runaway threshold in air. \textit{Plasma Physics and Controlled Fusion}. Institute of Physics, 2016, vol.~58, No~4, p.~''nestrankovano'', 9 pp. ISSN~0741-3335. Available from: https://dx.doi.org/10.1088/0741-3335/58/4/044001.

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