scholarly journals Evaluation of Monte Carlo tools for high energy atmospheric physics II: relativistic runaway electron avalanches

2018 ◽  
Author(s):  
David Sarria ◽  
Casper Rutjes ◽  
Gabriel Diniz ◽  
Alejandro Luque ◽  
Kevin M. A. Ihaddadene ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Runaway Electron ◽  
Gamma Ray ◽  
Full Range ◽  
High Energy ◽  
Atmospheric Physics ◽  
Average Electron Energy ◽  
Electron Avalanches ◽  
Set Up

Abstract. The emerging field of High Energy Atmospheric Physics studies events producing high energy particles and associated with thunderstorms, such as terrestrial gamma-ray flashes and gamma-ray glows. Understanding these phenomena requires appropriate models of the interaction of electrons, positrons and photons with air and electric fields. This work is made as a continuation of Rutjes et al. (2016), now including the effects of electric fields. We investigated results of three codes used in the community (Geant4, GRRR and REAM), for simulating the process of Relativistic Runaway Electron Avalanches. From analytical considerations, we show that the avalanche is mainly driven by electric fields and the ionisation and scattering processes determining the minimum energy of electrons that can runaway. To investigate this point further, we used a first simulation set-up to estimate the probability to produce a RREA from a relevant range of electron energies and electric field magnitudes. We found that the stepping methodology is important, and the stepping parameters have to be set up very carefully for Geant4. For example, a too large step size can lead to an avalanche probability reduced by a factor of 10, or a 40 % over-estimation of the average electron energy. Furthermore, the probability for the particles below 10 keV to accelerate and participate in the penetrating radiation is actually negligible for the full range of electric field we tested (E 

scholarly journals Evaluation of Monte Carlo tools for high-energy atmospheric physics II: relativistic runaway electron avalanches

2018 ◽  
Vol 11 (11) ◽  
pp. 4515-4535 ◽  
Author(s):  
David Sarria ◽  
Casper Rutjes ◽  
Gabriel Diniz ◽  
Alejandro Luque ◽  
Kevin M. A. Ihaddadene ◽  
...  
Keyword(s):  
Electron Energy ◽  
Electric Fields ◽  
Runaway Electron ◽  
High Energy ◽  
Energy Spectra ◽  
Breakdown Field ◽  
Atmospheric Physics ◽  
Electron Avalanches ◽  
Set Up ◽  
Good Agreement

Abstract. The emerging field of high-energy atmospheric physics studies how high-energy particles are produced in thunderstorms, in the form of terrestrial γ-ray flashes and γ-ray glows (also referred to as thunderstorm ground enhancements). Understanding these phenomena requires appropriate models of the interaction of electrons, positrons and photons with air molecules and electric fields. We investigated the results of three codes used in the community – Geant4, GRanada Relativistic Runaway simulator (GRRR) and Runaway Electron Avalanche Model (REAM) – to simulate relativistic runaway electron avalanches (RREAs). This work continues the study of Rutjes et al. (2016), now also including the effects of uniform electric fields, up to the classical breakdown field, which is about 3.0 MV m−1 at standard temperature and pressure. We first present our theoretical description of the RREA process, which is based on and incremented over previous published works. This analysis confirmed that the avalanche is mainly driven by electric fields and the ionisation and scattering processes determining the minimum energy of electrons that can run away, which was found to be above ≈10 keV for any fields up to the classical breakdown field. To investigate this point further, we then evaluated the probability to produce a RREA as a function of the initial electron energy and of the magnitude of the electric field. We found that the stepping methodology in the particle simulation has to be set up very carefully in Geant4. For example, a too-large step size can lead to an avalanche probability reduced by a factor of 10 or to a 40 % overestimation of the average electron energy. When properly set up, both Geant4 models show an overall good agreement (within ≈10 %) with REAM and GRRR. Furthermore, the probability that particles below 10 keV accelerate and participate in the high-energy radiation is found to be negligible for electric fields below the classical breakdown value. The added value of accurately tracking low-energy particles (<10 keV) is minor and mainly visible for fields above 2 MV m−1. In a second simulation set-up, we compared the physical characteristics of the avalanches produced by the four models: avalanche (time and length) scales, convergence time to a self-similar state and energy spectra of photons and electrons. The two Geant4 models and REAM showed good agreement on all parameters we tested. GRRR was also found to be consistent with the other codes, except for the electron energy spectra. That is probably because GRRR does not include straggling for the radiative and ionisation energy losses; hence, implementing these two processes is of primary importance to produce accurate RREA spectra. Including precise modelling of the interactions of particles below 10 keV (e.g. by taking into account molecular binding energy of secondary electrons for impact ionisation) also produced only small differences in the recorded spectra.

Simple "Reactor model" of relativistic runaway electron avalanches dynamics

2021 ◽  
Author(s):  
Egor Stadnichuk ◽  
Daria Zemlianskay ◽  
Victoria Efremova
Keyword(s):  
Electric Field ◽  
Gamma Rays ◽  
Runaway Electron ◽  
Gamma Ray ◽  
Negative Charge ◽  
Feedback Mechanism ◽  
Runaway Electrons ◽  
Reactor Model ◽  
Discharge Model ◽  
Electron Avalanches

&lt;p&gt;A possible mechanism responsible for Terrestrial Gamma-ray Flashes (TGFs) is feedback in the relativistic runaway electron avalanches (RREA) dynamics. In this research, a new way of RREAs self-sustaining is suggested. This self-sustaining feedback can be described in the following way. Let the thundercloud consist of two regions with the electric field so that runaway electrons accelerated in one region move in the direction of another one and vice versa. For instance, such an electric field structure might appear with one positive charge layer situated between two negative charge layers. In this system, the following feedback mechanism occurs. An RREA developing in one region will produce bremsstrahlung gamma-rays. These gamma-rays will propagate into another region and produce RREAs within it. These RREAs will develop backward and radiate gamma-rays, which will penetrate the first region, generating secondary RREAs. In this way, the primary avalanche reproduced itself by the gamma-ray exchange between two sideways oriented areas with the electric field. In this work, it is shown that the electric field values required for TGF generation by this mechanism are lower than values required in Relativistic Feedback Discharge Model.&lt;/p&gt;

scholarly journals Relativistic runaway electron avalanches within complex thunderstorm electric field structures

2021 ◽  
Author(s):  
Egor Stadnichuk ◽  
Ekaterina Svechnikova ◽  
Alexander Nozik ◽  
Daria Zemlianskaya ◽  
Timur Khamitov ◽  
...  
Keyword(s):  
Electric Field ◽  
Runaway Electron ◽  
Electron Avalanches

Fringe fields are important when examining molecular orientation in a cold ammonia beam

2021 ◽  
Author(s):  
Paul Bertier ◽  
Brianna Heazlewood
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Molecular Orientation ◽  
Molecular Beam ◽  
Buffer Gas ◽  
State Distribution ◽  
Experimental Apparatus ◽  
Set Up ◽  
A Minor ◽  
Fringe Fields

Abstract External fields have been widely adopted to control and manipulate the properties of gas-phase molecular species. In particular, electric fields have been shown to focus, filter and decelerate beams of polar molecules. While there are several well-established approaches for controlling the velocity and quantum-state distribution of reactant molecules, very few of these methods have examined the orientation of molecules in the resulting beam. Here we show that a buffer gas cell and three-bend electrostatic guide (coupled to a time-of-flight set-up) can be configured such that 70% of ammonia molecules in the cold molecular beam are oriented to an external electric field at the point of detection. With a minor alteration to the set-up, an approximately statistical distribution of molecular orientation is seen. These observations are explained by simulations of the electric field in the vicinity of the mesh separating the quadrupole guide and the repeller plate. The combined experimental apparatus therefore offers control over three key properties of a molecular beam: the rotational state distribution, the beam velocity, and the molecular orientation. Exerting this level of control over the properties of a molecular beam opens up exciting prospects for our ability to understand what role each parameter plays in reaction studies.

scholarly journals Model for Deformation of Cells from External Electric Fields at or Near Resonant Frequencies

2020 ◽  
Author(s):  
L. Martinez ◽  
A. Dhruv ◽  
L. Lin ◽  
E. Balaras ◽  
M. Keidar
Keyword(s):  
Electric Field ◽  
Cancer Cells ◽  
Electric Fields ◽  
High Energy ◽  
Atmospheric Plasma ◽  
Maximum Effect ◽  
Viscoelastic Response ◽  
Resonant Frequencies ◽  
Wave Source ◽  
External Electric Fields

AbstractThis paper presents a numerical model to investigate the deformation of biological cells by applying external electric fields operating at or near cell resonant frequencies. Cells are represented as pseudo solids with high viscosity suspended in liquid media. The electric field source is an atmospheric plasma jet developed inhouse, for which the emitted energy distribution has been measured.Viscoelastic response is resolved in the entire cell structure by solving a deformation matrix assuming an isotropic material with a prescribed modulus of elasticity. To investigate cell deformation at resonant frequencies, one mode of natural cell oscillation is considered in which the cell membrane is made to radially move about its eigenfrequency. An electromagnetic wave source interacts with the cell and induces oscillation and viscoelastic response. The source carries energy in the form of a distribution function which couples a range of oscillating frequencies with electric field amplitude.Results show that cell response may be increased by the external electric field operating at or near resonance. In the elastic regime, response increases until a steady threshold value, and the structure moves as a damped oscillator. Generally, this response is a function of both frequency and magnitude of the source, with a maximum effect found at resonance. To understand the full effect of the source energy spectrum, the system is solved by considering five frequency-amplitude couplings. Results show that the total solution is a nonlinear combination of the individual solutions. Additionally, sources with different signal phases are simulated to determine the effect of initial conditions on the evolution of the system, and the result suggests that there may be multiple solutions within the same order of magnitude for elastic response and velocity. Cell rupture from electric stress may occur during application given a high energy source.SignificanceCold atmospheric plasma jets (CAPJs) have been widely researched for their potential applications in cancer therapy. Existing research has focused mainly on the ability of CAPJs to deliver a mixture of reactive species which can be absorbed by cancer cells and induce cell death. The objective of our study is to investigate the mechanical effect of CAPJ electromagnetic (EM) waves on interacting cells. By coupling the EM waves associated with plasma frequency and cell viscoelastic response, we have developed a numerical tool to investigate cell damage either by mechanical or thermal loads. This work is motivated by the promise of EM waves to function as a sensitizing agent for cancer cells in preparation for chemotherapy.

scholarly journals Relativistic runaway electron avalanches within complex thunderstorm electric field structures

2021 ◽  
Author(s):  
E. Stadnichuk ◽  
E. Svechnikova ◽  
A. Nozik ◽  
D. Zemlianskaya ◽  
T. Khamitov ◽  
...  
Keyword(s):  
Electric Field ◽  
Runaway Electron ◽  
Electron Avalanches

An Electroscope System Based on Electric Field Measurement Method for UHV Transmission Lines

2009 ◽  
Vol 10 (2) ◽  
Author(s):  
Fan Yang ◽  
Wei He ◽  
Tao Chen ◽  
Xiaochu Luo ◽  
Yongchang Fu
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Transmission Lines ◽  
Field Measurement ◽  
Measurement Method ◽  
Electric Field Measurement ◽  
Set Up ◽  
Global Regularization ◽  
Uhv Transmission Lines ◽  
Internet Network

The paper describes an electric field measurement method based electroscope system to check the electrification state of ultra-high voltage transmission lines, which is composed of three parts: 1) Measuring terminal; 2) Central sever; 3) GPRS and Internet network. The measuring terminal was used to measure the electric field and the location of the measuring points, then the measured data was sent to the central sever by GPRS and Internet network, and requested for an electricity state confirmation.When the sever received a request from a terminal, the electric fields and locations of the measuring points were obtained first, then according to the location of the measuring points, the server searches the corresponding objective transmission lines in the database and read their parameters. According to the parameters of the measuring points and transmission lines, a calculation would be carried out to confirm the electrification state of the transmission lines. For the confirmation calculation, equations for the electric field inverse problem of the transmission lines were set up first, then global regularization and damped Gauss Newton (DGN) method were used to solve the inverse problem.A 500kV double loops transmission line was taken as an example to verify the validity of this method. The electric field and location of 11 measuring points were measured by the measuring terminal firstly, and then sent to the central sever. Electrification state was confirmed by the central sever.

Design, Build and Test of the VOEvent Network for the SVOM Chinese Ground Segment

2017 ◽  
Vol 14 (S339) ◽  
pp. 353-353
Author(s):  
M. Zhang ◽  
M. Huang ◽  
C. Wu
Keyword(s):  
Data Reduction ◽  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Collaborative Project ◽  
Transient Phenomena ◽  
Ground Segment ◽  
Design Build ◽  
Science Centre ◽  
Set Up

AbstractThe Space-based, multi-band, astronomical Variable Object Monitor (SVOM) is a collaborative project between China and France dedicated to the detection, localisation and study of about 60 Gamma Ray Bursts per year, and other high-energy transient phenomena. SVOM is planned to be launched in 2021, with a lifetime of 3–5 years. The poster described our construction and testing of a prototype to set up an interface between our data reduction sub-system, the global VOEvent network, and the French science centre.

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