Diffusion of relativistic runaway electrons and implications for lightning initiation

2010 ◽  
Vol 115 (A3) ◽  
pp. n/a-n/a ◽  
Author(s):  
Joseph R. Dwyer
Keyword(s):  
Runaway Electrons ◽  
Lightning Initiation

Method for the numerical calculation of the mechanism of the origin the NBE (CID) due to the volume phase wave of synchronous ignition of streamer flashes by EAS-RREA

2020 ◽  
Author(s):  
Andrey Vlasov ◽  
Mikhail Fridman ◽  
Alexander Kostinskiy
Keyword(s):  
Numerical Calculation ◽  
Electric Field ◽  
Strong Electric Field ◽  
High Energy ◽  
Theoretical Physics ◽  
Runaway Electrons ◽  
Entire Volume ◽  
Volume Phase ◽  
Phase Wave ◽  
Lightning Initiation

<p>In an article by Kostinskiy et al. (2019) proposed the mechanism of the origin and development of lightning from initiating event to initial breakdown pulses (termed the Mechanism). The Mechanism assumes initiation occurs in a region of a thundercloud of 1 km<sup>3</sup> with electric field E > 0.3-0.4 MV/(m∙atm), which contains, because of turbulence, numerous small “E<sub>th</sub>-volumes” of 0.001 m<sup>3</sup> with E ≥ 3 MV/(m∙atm). The Mechanism allows for lightning initiation by two observed types of initiating events: a high power VHF event called an NBE (narrow bipolar event or CID), or a weak VHF event. According to the Mechanism, both types of initiating events are caused by a group of relativistic runaway electron avalanche particles passing through many of the E<sub>th</sub>-volumes, thereby causing the nearly simultaneous launching of many positive streamer flashes.</p><p>This report describes the method for the numerical calculation of the volume phase wave of ignition of streamer flashes in the turbulent region of a thundercloud, which is initiated by secondary particles of a extensive air shower (EAS).  The lateral distribution of energetic electrons and positrons, which are created by cosmic particles with an energy ε> 10<sup>15</sup> eV, is described by the equation Nishimura-Kamata-Greizen (Kamata & Nishimura, 1958). When an EAS enters an electric field with an intensity of E> 400 kV /(m∙atm), which supports the movement of streamers, the electron runaway mechanism  is sure to start working (runaway threshold E> 280 kV/ (m∙atm), Dwyer, 2010). Each secondary electron and positron EAS initiates an avalanche of runaway electrons. The radial distribution of each avalanche was calculated in the diffusion approximation using the Dwyer-Babich approximation formulas (Dwyer, 2010; Babich & Bochkov, 2011). The model considered the effect of electrons of each such avalanche on the entire volume of a strong electric field.</p><p>The calculation showed that the EAS-RREA mechanism of almost simultaneous volumetric initiation of multiple streamer flashes can provide such NBE (CID) parameters as current and charge transfer at observation heights of 5–20 km above sea level.</p><p><strong>References</strong></p><p>Babich, L.P., Bochkov, E.I. (2011). Deterministic methods for numerical simulation of high-energy runaway electron avalanches. Journal of Experimental and Theoretical Physics, 112(3), 494–503, doi: 10.1134/S1063776111020014.</p><p>Dwyer, J. R. (2010), Diffusion of relativistic runaway electrons and implications for lightning initiation, J. Geophys. Res., 115, A00E14, doi:10.1029/2009JA014504.</p><p>Kamata, K., & Nishimura, J. (1958). The lateral and the angular structure functions of electron showers. Progress of Theoretical Physics Supplement, 6, 93. https://doi.org/10.1143/PTPS.6.93</p><p>Kostinskiy, A. Yu., Marshall, T.C., Stolzenburg, M. (2019), The Mechanism of the Origin and Development of Lightning from Initiating Event to Initial Breakdown Pulses, arXiv:1906.01033</p><p>Raizer Yu. (1991), Gas Discharge Physics, Springer-Verlag, 449 p.</p>

The mechanism of the origin the NBE (CID) and the initiating event (IE) of lightning due to the volume phase wave of EAS-RREA synchronous ignition of streamer flashes

2020 ◽  
Author(s):  
Alexander Kostinskiy ◽  
Thomas Marshall ◽  
Maribeth Stolzenburg
Keyword(s):  
Electric Field ◽  
Runaway Electron ◽  
Strong Electric Field ◽  
Cosmic Ray ◽  
Relativistic Electrons ◽  
Runaway Electrons ◽  
Air Showers ◽  
Secondary Electrons ◽  
Lightning Initiation ◽  
Positive Streamer

<p>In an article by <em>Kostinskiy et al. (2019)</em> proposed the mechanism of the origin and development of lightning from initiating event to initial breakdown pulses (termed the Mechanism). The Mechanism assumes initiation occurs in a region of a thundercloud of 1 km<sup>3</sup> with electric field E > 0.4 MV/(m∙atm), which contains, because of turbulence, numerous small “E<sub>th</sub>-volumes” of 0.001-0.0001 m<sup>3</sup> with E ≥ 3 MV/(m∙atm). The Mechanism allows for lightning initiation by two observed types of initiating events: a high power VHF event called an NBE (narrow bipolar event or CID), or a weak VHF event. According to the Mechanism, both types of initiating events are caused by a group of relativistic runaway electron avalanche particles passing through many of the E<sub>th</sub>-volumes, thereby causing the nearly simultaneous launching of many positive streamer flashes, <em>Kostinskiy et al. (2019)</em>.</p><p>In this report, based on the Meek’s criterion for the initiation of streamers (<em>Raizer, 1991</em>) at different heights of lightning initiation and taking into account the number of all background electrons, positrons and photons of cosmic rays with energy ε < 10<sup>12</sup> eV (<em>Sato, 2015</em>) crossing E<sub>th</sub>-volumes sizes of E<sub>th</sub>-volumes are specified (3∙10<sup>-4</sup>-3∙10<sup>-5</sup> m<sup>3</sup>). The report also showed that synchronous injection with a high probability of relativistic electrons into such small E<sub>th</sub>-volumes requires of relativistic runaway electrons avalanches to be initiated by extensive air showers with energies ε > 10<sup>15</sup> eV, which would supply (injected) 10<sup>5</sup>-10<sup>7</sup> secondary electrons into a turbulent region of a thundercloud with a strong electric field.</p><p>References</p><p>Kostinskiy, A. Yu., Marshall, T.C., Stolzenburg, M. (2019), The Mechanism of the Origin and Development of Lightning from Initiating Event to Initial Breakdown Pulses arXiv:1906.01033</p><p>Raizer Yu. (1991), Gas Discharge Physics, Springer-Verlag, 449 p.</p><p>Sato T. (2015), Analytical Model for Estimating Terrestrial Cosmic Ray Fluxes Nearly Anytime and Anywhere in the World: Extension of PARMA/EXPACS, PLOS ONE, 10(12): e0144679.</p>

scholarly journals Spatiotemporal analysis of the runaway distribution function from synchrotron images in an ASDEX Upgrade disruption

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
M. Hoppe ◽  
L. Hesslow ◽  
O. Embreus ◽  
L. Unnerfelt ◽  
G. Papp ◽  
...  
Keyword(s):  
Radial Profile ◽  
Spatiotemporal Analysis ◽  
High Energy ◽  
Synchrotron Emission ◽  
Analytic Model ◽  
Runaway Electrons ◽  
Radial Density ◽  
Radial Density Profile ◽  
Argon Injection ◽  
Seed Population

Synchrotron radiation images from runaway electrons (REs) in an ASDEX Upgrade discharge disrupted by argon injection are analysed using the synchrotron diagnostic tool Soft and coupled fluid-kinetic simulations. We show that the evolution of the runaway distribution is well described by an initial hot-tail seed population, which is accelerated to energies between 25–50 MeV during the current quench, together with an avalanche runaway tail which has an exponentially decreasing energy spectrum. We find that, although the avalanche component carries the vast majority of the current, it is the high-energy seed remnant that dominates synchrotron emission. With insights from the fluid-kinetic simulations, an analytic model for the evolution of the runaway seed component is developed and used to reconstruct the radial density profile of the RE beam. The analysis shows that the observed change of the synchrotron pattern from circular to crescent shape is caused by a rapid redistribution of the radial profile of the runaway density.

scholarly journals Effects of magnetic perturbations and radiation on the runaway avalanche

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
P. Svensson ◽  
O. Embreus ◽  
S. L. Newton ◽  
K. Särkimäki ◽  
O. Vallhagen ◽  
...  
Keyword(s):  
Growth Rate ◽  
Runaway Electrons ◽  
Plasma Parameters ◽  
Perturbative Approach ◽  
Efficient Simulation ◽  
Strong Current ◽  
Magnetic Perturbations ◽  
Space Dynamics ◽  
Stochastic Magnetic Fields ◽  
Mitigation Methods

The electron runaway phenomenon in plasmas depends sensitively on the momentum- space dynamics. However, efficient simulation of the global evolution of systems involving runaway electrons typically requires a reduced fluid description. This is needed, for example, in the design of essential runaway mitigation methods for tokamaks. In this paper, we present a method to include the effect of momentum-dependent spatial transport in the runaway avalanche growth rate. We quantify the reduction of the growth rate in the presence of electron diffusion in stochastic magnetic fields and show that the spatial transport can raise the effective critical electric field. Using a perturbative approach, we derive a set of equations that allows treatment of the effect of spatial transport on runaway dynamics in the presence of radial variation in plasma parameters. This is then used to demonstrate the effect of spatial transport in current quench simulations for ITER-like plasmas with massive material injection. We find that in scenarios with sufficiently slow current quench, owing to moderate impurity and deuterium injection, the presence of magnetic perturbations reduces the final runaway current considerably. Perturbations localised at the edge are not effective in suppressing the runaways, unless the runaway generation is off-axis, in which case they may lead to formation of strong current sheets at the interface of the confined and perturbed regions.

scholarly journals A distinct negative leader propagation mode

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
O. Scholten ◽  
B. M. Hare ◽  
J. Dwyer ◽  
N. Liu ◽  
C. Sterpka ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Electric Discharge ◽  
Radio Astronomy ◽  
Propagation Mode ◽  
Common Phenomenon ◽  
High Charge ◽  
Initial Stage ◽  
Lightning Initiation ◽  
The Common

AbstractThe common phenomenon of lightning still harbors many secrets such as what are the conditions for lightning initiation and what is driving the discharge to propagate over several tens of kilometers through the atmosphere forming conducting ionized channels called leaders. Since lightning is an electric discharge phenomenon, there are positively and negatively charged leaders. In this work we report on measurements made with the LOFAR radio telescope, an instrument primarily build for radio-astronomy observations. It is observed that a negative leader rather suddenly changes, for a few milliseconds, into a mode where it radiates 100 times more VHF power than typical negative leaders after which it spawns a large number of more typical negative leaders. This mode occurs during the initial stage, soon after initiation, of all lightning flashes we have mapped (about 25). For some flashes this mode occurs also well after initiation and we show one case where it is triggered twice, some 100 ms apart. We postulate that this is indicative of a small (order of 5 km$$^2$$ 2 ) high charge pocket. Lightning thus appears to be initiated exclusively in the vicinity of such a small but dense charge pocket.

Development of a hard X-ray detector for measuring continuous spectra generated by runaway electrons in VEST

2021 ◽  
Vol 170 ◽  
pp. 112522
Author(s):  
Soobin Lim ◽  
Jonggab Jo ◽  
Changwook Koo ◽  
Sung-Joon Ye ◽  
Kyoung-Jae Chung ◽  
...  
Keyword(s):  
Runaway Electrons ◽  
X Ray

Suppression of runaway electron generation by massive helium injection after induced disruptions on TEXTOR

2015 ◽  
Vol 81 (5) ◽  
Author(s):  
A. Lvovskiy ◽  
H. R. Koslowski ◽  
L. Zeng ◽  
Keyword(s):  
Time Delay ◽  
Runaway Electron ◽  
Critical Density ◽  
Runaway Electrons ◽  
Electron Generation ◽  
Disruption Mitigation ◽  
Order Of Magnitude ◽  
Short Time ◽  
Short Time Delay

Disruptions with runaway electron generation have been deliberately induced by injection of argon using a disruption mitigation valve. A second disruption mitigation valve has been utilised to inject varying amounts of helium after a short time delay. No generation of runaway electrons has been observed when more than a critical amount of helium has been injected no later than 5 ms after the triggering of the first valve. The required amount of helium for suppression of runaway electron generation is up to one order of magnitude lower than the critical density according to Connor & Hastie (1975) and Rosenbluth & Putvinski (1997).

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