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Influence of the angular scattering of electrons on the runaway threshold in air
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bonaventura Bourdon Neubert |
| Copyright Year | 2018 |
| Abstract | The runaway electron mechanism is of great importance for the understanding of the generation of xand 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. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://orbit.dtu.dk/ws/files/121796950/Influence_of_the_angular_scattering_of_electrons_on_the_runaway_threshold_in_air.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | AngularJS Avalanches Body Fluid Discharge British undergraduate degree classification Class Coefficient Cross-sectional data Discharger Electron Electrons Emission - Male genitalia finding Equivalent Weight First-class function Friction Gamma Rays Hot flushes Interferon Type II Kind of quantity - Equilibrium Leucaena pulverulenta Lindane Monte Carlo method One-electron universe Radiation Seizures Terrestrial television Test case Thermal runaway Trivial Graph Format Velocity (software development) collision electric field |
| Content Type | Text |
| Resource Type | Article |
