DOCSLIB.ORG

Relativistic Runaway Electron Avalanches Inside the High Field Regions of Thunderclouds by Eric Scott Cramer

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Relativistic Runaway Electron Avalanches Inside the High Field Regions of Thunderclouds by Eric Scott Cramer Relativistic Runaway Electron Avalanches Inside the High Field Regions of Thunderclouds by Eric Scott Cramer Bachelor of Science, Physics & Applied Mathematics CUNY Queens College 2008 Master of Science, Space Sciences Florida Institute of Technology 2011 A dissertation submitted to Florida Institute of Technology in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physics Melbourne, Florida May 2015 ⃝c 2015 Eric Scott Cramer All Rights Reserved The author grants permission to make single copies We the undersigned committee hereby recommends that the attached document be accepted as fulfilling in part of the requirements for the degree of Doctor of Philosophy in Physics. \Relativistic Runaway Electron Avalanches Inside the High Field Regions of Thunderclouds" a dissertation by Eric Scott Cramer Major Advisor Hamid K. Rassoul, Ph.D. Dean, College of Science Professor, Physics and Space Sciences Co-Advisor Joseph R. Dwyer, Ph.D. Professor, Physics, University of New Hampshire Peter T. Paul Chair in Space Sciences Ningyu Liu, Ph.D. Associate Professor, Physics and Space Sciences Ming Zhang, Ph.D. Professor, Physics and Space Sciences Ugur Abdulla, Ph.D. Department Head, Mathematical Sciences Professor, Mathematical Sciences Abstract Relativistic Runaway Electron Avalanches Inside the High Field Regions of Thunderclouds by Eric Scott Cramer Dissertation Advisor: Hamid K. Rassoul, Ph.D. In this dissertation, simplified equations describing the transport and energy spec- trum of runaway electrons are derived from the basic kinematics of the continuity equations. These equations are useful in modeling the energy distribution of ener- getic electrons in strong electric fields, such as those found inside thunderstorms. Dwyer and Babich [2011] investigated the generation of low-energy electrons in relativistic runaway electron avalanches. The paper also developed simple ana- lytical expressions to describe the detailed physics of Monte Carlo simulations of relativistic runaway electrons in air. In this work, the energy spectra of the run- away electron population are studied in detail. Dependence of electron avalanche development on properties such as the avalanche length, radiation length, and the effective Møller scattering efficiency factor, are discussed in detail. To describe the shapes of the electron energy spectra for a wide range of electric field strengths, the random deviation of electron energy loss from the mean value is added to the solutions. We find that this effect helps maintain an exponential energy spectrum for electric fields that approach the runaway electron threshold field. We also investigate the source mechanisms of Terrestrial Gamma-ray Flashes, which are a result of relativistic runaway electron avalanches in air. In this study, the bremsstrahlung photons are propagated through the atmosphere, where they undergo Compton scattering, pair production, and photoelectric absorption. We model these interactions with a Monte Carlo simulation from the TGF source lo- cation (assumed to vary between 8 and 20 km) and the edge of the atmosphere (≈ 100 km). We then propagate these photons to a satellite plane at 568 km in order to compare with measurements. In collaboration with the GBM instrument team in Huntsville, AL, we were able to model spectral and temporal properties of observed TGFs. Although the analysis of individual TGF photon spectra was qualitative, we were able to put some constraints, i.e. source altitude and beaming angle, on a sample of observed GBM TGFs. However, assuming a height of 15 km, we were able to model the softening in the spectrum observed as the satel- lite moves off-axis from the TGF source location [Fitzpatrick et al., 2014]. The conclusion of this analysis shows that Compton scattering alone can not explain the temporal dispersion observed. This suggests that an intrinsic time variation exists at the source of the TGF. iii Contents Abstract iii List of Figures vii List of Tables ix Abbreviations x Symbols xi Acknowledgements xiii Dedication xvi 1 Introduction 1 1.1 Motivation ............................... 1 1.2 High-Energy Atmospheric Physics .................. 3 1.2.1 Relativistic Runaway Electron Avalanches (RREAs) . 3 1.2.2 Relativistic Feedback ...................... 6 1.2.3 X-rays from Lightning ..................... 10 1.2.4 Terrestrial Gamma-ray Flashes . 13 1.3 Monte Carlo Simulations ........................ 18 1.4 Scientific Contributions ........................ 23 2 Electron Interactions in Air 24 2.1 Motion in a Uniform Electric Field . 24 2.2 Brownian Motion ............................ 26 2.3 Avalanche Length, λe− ......................... 28 2.4 Bethe Formula for Ionization Energy Loss . 30 iv 2.4.1 Minimum Runaway Electron Energy, "th . 31 2.5 Møller Scattering ............................ 32 2.5.1 Differential Cross Section ................... 32 2.5.2 Efficiency Factor, ξeff ..................... 34 2.6 Electron-Nuclear Bremsstrahlung ................... 37 2.6.1 Triply Differential Cross Section . 37 2.6.2 Radiation Length, X0 ..................... 40 2.6.3 Energy Loss Formula ...................... 42 2.7 Coulomb Scattering .......................... 42 2.7.1 Differential Cross Section ................... 42 2.7.2 Root Mean Square Scattering Angle, θrms . 45 3 Runaway Electron Energy Spectra 48 3.1 Derivation of the Kinetic Equation . 48 3.2 An Analytical Approach ........................ 55 3.2.1 Simple Exponential Model ................... 57 3.2.2 Møller Scattering Source Term . 58 3.2.3 Radiative Losses ........................ 61 3.2.4 Random Walk Model ...................... 65 3.3 Average Kinetic Energy ........................ 74 3.4 Discussion ................................ 75 4 TGF Source Mechanisms 78 4.1 GBM Observations ........................... 78 4.2 Photon Interactions .......................... 83 4.2.1 Compton Scattering ...................... 84 4.2.2 Photo-Electric Absorption ................... 86 4.2.3 Pair Production ........................ 87 4.3 Source Properties of Energetic Photons . 88 4.3.1 Photon Energy Spectrum ................... 88 4.3.2 Angular Distribution ...................... 90 4.3.3 Particle Composition of the Beam . 92 4.4 γ-Ray Propagation in the Atmosphere . 93 4.5 Monte Carlo Modeling of GBM Data . 98 4.5.1 Spectral Analysis . 100 4.5.2 Temporal Analysis . 106 4.6 Discussion ................................ 111 5 Conclusions and Suggestions for Future Work 114 5.1 Conclusions ............................... 114 5.2 Suggestions for Future Work . 116 v A Green's Function Calculation 117 B Calculation of Electron Energy Loss Fluctuations 119 C The Diffusion Term 127 C.1 Derivation of the Fokker Planck Equation . 127 C.2 Method of Determining the Diffusion Coefficients . 130 C.3 Sturm-Liouville Form . 132 Bibliography 133 vi List of Figures 1.1 Effective frictional force experienced by a free electron in air . 4 1.2 Graphic of a runaway electron avalanche ............... 6 1.3 Relativistic feedback from a Monte Carlo simulation . 8 1.4 Summary of production methods for runaway electrons . 9 1.5 X-rays from lightning as observed by Moore et al. [2001] . 11 1.6 X-rays from lightning as observed by Dwyer et al. [2004] . 12 1.7 BATSE observation of a TGF ..................... 14 1.8 RHESSI TGF spectrum and model fits . 15 1.9 Cross section of the REAM Monte Carlo simulation . 20 1.10 REAM simulation of an electron avalanche . 22 2.1 Graphic of an electron in a uniform electric field . 25 2.2 Electron avalanche length ....................... 29 2.3 Minimum runaway electron energy, "th . 32 2.4 Møller scattering Feynman diagram . 33 2.5 Møller efficiency factor ......................... 36 2.6 Radiation length ............................ 41 2.7 Coulomb effects on electron path of travel . 44 2.8 Empirical fits for Coulomb scattering . 45 3.1 Solutions to Equation (3.36) using the approaches in sections 3.2.1 & 3.2.2 .................................. 60 3.2 Maximum runaway electron energy, "max . 63 3.3 Solutions to Equation (3.36) using the approach in section 3.2.3 . 65 3.4 Width of the energy fluctuations used in the random walk model . 68 3.5 Gaussian distributions of runaway electron energy fluctuations as a function of primary electron energy . 70 3.6 Gaussian distributions of runaway electron energy fluctuations as a function of applied electric field .................... 72 3.7 Solutions to Equation (3.27) using the approaches in sections 3.2.3 & 3.2.4 .................................. 73 vii 3.8 Average runaway electron energy as a function of applied electric field ................................... 75 4.1 GBM detected TGF from Briggs et al. [2010] . 79 4.2 Symmetric and asymmetric time profiles of two separate TGF events. Figure taken from Briggs et al. [2010] . 80 4.3 GBM spectral data and model fits from Briggs et al. [2011] . 82 4.4 Total cross sections for photon interactions in nitrogen . 83 4.5 Graphic of Compton scattering .................... 84 4.6 Photon differential energy spectra produced by the REAM Monte Carlo simulation ............................ 89 4.7 Simulated γ-ray angular distribution . 90 4.8 Simulated γ-ray rms angular distribution . 91 4.9 Ratio of the number of γ-rays to the number of electrons inside the avalanche region ............................ 93 4.10 Cartoon of γ-ray propagation using REAM . 95 4.11 Intrinsic γ-ray beam shape from the REAM simulation at the top of the atmosphere ........................... 97 4.12 Particle concentration at the top of the atmosphere for a wide
Load more

Recommended publications
  • Relativistic Runaway Electrons Above Thunderstorms
    Relativistic Runaway Electrons above Thunderstorms Nikolai G. Lehtinen Physics Department STAR Laboratory Stanford University Advisers: Umran S. Inan, EE Department, Timothy F. Bell, EE Department, Roger W. Romani, Physics Department Plan 1. Introduction 2. Monte Carlo model of runaway electron avalanche 3. Fluid model of runaway electrons above thunderstorms 4. Effects of runaway electrons in the conjugate hemisphere Lightning-mesosphere interaction phenomena ~ 2000 cm-3 Electron density Β 100 km THERMOSPHERE Elves 80 km Sprites MESOSPHERE γ-rays 60 km Runaway ~100 MV 40 km E ~ 103 V/m electrons STRATOSPHERE at 40 km Blue Jet 20 km Cameras + + + + + TROPOSPHERE +CG 0 km - --- - γ-ray flash Red Sprites (BATSE observation) 40 Elves 30 20 Sprites 10 Rate (counts/0.1ms) 0 015205 10 1996.204.07.17.38.792 Time (ms) Red Sprites Red Sprites: - altitude range ~50-90 km - lateral extent ~5-10 km - occur ~1-5 ms after +CG discharge - last up to several 10 ms Aircraft view Ground View 90-95 km horizon Space Shuttle View sprite sprite thunderstorm Examples of Terrestrial Gamma Ray Flashes (BATSE Data) Terrestrial Gamma Rays: - time duration ~1 ms - energies 20 keV—2 MeV - hard spectrum (bremsstrahlung) Rate (counts/0.1ms) Rate (counts/0.1ms) Rate (counts/0.1ms) Time (ms) Time (ms) Time (ms) Time (ms) C. T. R. Wilson, 1925 While the electric force due to the thundercloud falls off rapidly, ... the electric force required to cause sparking ... falls off still more rapidly. Thus, ... there will be a height above which the electric force due to the cloud exceeds the sparking limit ..
    [Show full text]
  • Runaway Electrons During Subnanosecond Breakdowns in High- Pressure Gases
    Page 1 of 25 High Voltage This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication in an issue of the journal. To cite the paper please use the doi provided on the Digital Library page. Runaway electrons during subnanosecond breakdowns in high- pressure gases Victor F. Tarasenko *, Mikhail I. Lomaev, Dmitry V. Beloplotov, Dmitry A. Sorokin Institute of High Current Electronics Siberian Branch, Russian Academy of Science, 2/3 Akademicheskii Ave., Tomsk 634055. Russia *[email protected] Abstract: The parameters of runaway electrons produced in nanosecond high-voltage discharges in different gases (air, nitrogen, sulfur hexafluoride, krypton, argon, methane, neon, hydrogen, helium) at atmospheric and higher pressure were studied. An optical analysis was also performed to investigate the ionization dynamics in diffuse discharges in nitrogen and nitrogen-containing mixtures. At breakdown of a point-to-plane gap by nanosecond (≈2 ns) high-voltage (≈200 kV) pulses of negative voltage polarity and gas pressure above 0.1 MPa, a supershort avalanche electron beam (SAEB) was detected by a collector behind the flat anode. For pressure > 0.1 MPa of nitrogen and other gases it is shown that the maximum pressure for SAEB registration decreases with increasing the voltage pulse rise time. Therefore, to detect a SAEB at atmospheric and higher gas pressure, one should use voltage pulses with an amplitude of hundred kilovolts and rise time of ~1 ns and shorter. The experimental research in the dynamics of optical radiation from the discharge plasma shows that the breakdown in which runaway electrons are produced develops as an ionization wave.
    [Show full text]
  • Runaway Breakdown and Electrical Discharges in Thunderstorms
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 115, A00E60, doi:10.1029/2009JA014818, 2010 Runaway breakdown and electrical discharges in thunderstorms Gennady Milikh1 and Robert Roussel‐Dupré2 Received 22 August 2009; revised 2 August 2010; accepted 22 September 2010; published 24 December 2010. [1] This review considers the precise role played by runaway breakdown (RB) in the initiation and development of lightning discharges. RB remains a fundamental research topic under intense investigation. The question of how lightning is initiated and subsequently evolves in the thunderstorm environment rests in part on a fundamental understanding of RB and cosmic rays and the potential coupling to thermal runaway (as a seed to RB) and conventional breakdown (as a source of thermal runaways). In this paper, we describe the basic mechanism of RB and the conditions required to initiate an observable avalanche. Feedback processes that fundamentally enhance RB are discussed, as are both conventional breakdown and thermal runaway. Observations that provide clear evidence for the presence of energetic particles in thunderstorms/ lightning include g‐ray and X‐ray flux intensifications over thunderstorms, g‐ray and X‐ray bursts in conjunction with stepped leaders, terrestrial g‐ray flashes, and neutron production by lightning. Intense radio impulses termed narrow bipolar pulses (or NBPs) provide indirect evidence for RB particularly when measured in association with cosmic ray showers. Our present understanding of these phenomena and their enduring enigmatic character
    [Show full text]
  • Cosmic Ray Breakdown Mechanism in the Atmophere
    IOSR Journal of Applied Physics (IOSR-JAP) e-ISSN: 2278-4861.Volume 6, Issue 3 Ver. II (May-Jun. 2014), PP 62-64 www.iosrjournals.org Cosmic Ray Breakdown Mechanism in the Atmophere Akande, P. I[1], Azi Amaechi O.[2], A. O. Chikwendu[3], Nwoba Isreal A.[4] [1][2]Department of Industrial Physics, Ebonyi State University, Abakaliki [3]Department of Industrial Physics, Renaissance University, Ugbawka [4]Evangel University, Akaeze, PMB 126, Ebonyi State Abstract: Cosmic rays are high energy particles originating from outer space. These cosmic rays produce secondary cosmic rays as they enter the atmosphere and generate runaway electrons. The generation of runaway electrons in the relativistic region of the atmosphere is the focus of this work. To achieve our aim, basic consideration is given to the cold electron having mean velocity which is less than electron thermal speed. The effects of force on these electrons are obtained. From the result, it shows that cosmic ray breakdown occurs in the atmosphere within the relativistic region and the electrons are accelerated by the electric field. Hence there is an exponential increase of the fast electrons. This exponential increase in fast electron in the atmosphere could be the basic reason for the spontanouse characteristic behavour of most atmospheric processes. I. Introduction Most cosmic rays are thought to originate outside the solar system, with many coming from within our Milky Way Galaxy, and a few arriving from other galaxies, (James, 1998). This cosmic ray produce secondary particle which can be sufficiently energetic to contribute themselves to further ionization of the neutral gases.
    [Show full text]
  • JGRA20111A.Pdf (435.8Kb)
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 116, A09301, doi:10.1029/2011JA016494, 2011 Low‐energy electron production by relativistic runaway electron avalanches in air Joseph R. Dwyer1 and Leonid P. Babich2 Received 24 January 2011; revised 31 May 2011; accepted 8 June 2011; published 7 September 2011. [1] This paper investigates the production of low‐energy (few eV) electrons by relativistic runaway electron avalanches. This work is motivated by a growing body of literature that claims that runaway electron avalanches produce an anomalous growth of low‐energy electrons and hence an anomalously large electrical conductivity, a factor of 50 larger than expected from standard calculations. Such large enhancements would have a substantial impact on properties of runaway electron avalanches and their observable effects. Indeed, these purportedly large conductivities have been used to argue that runaway electron avalanches result in a novel form of electrical breakdown called “runaway breakdown.” In this paper, we present simple analytical calculations, detailed Monte Carlo simulations, and a review of the experimental literature to show that no such anomalous growth of low‐energy electron populations exists. Consequently, estimates of the conductivity generated by a runaway electron avalanche have been greatly exaggerated in many previous papers, drawing into question several of the claims about runaway breakdown. Citation: Dwyer, J. R., and L. P. Babich (2011), Low‐energy electron production by relativistic runaway electron avalanches in air, J. Geophys. Res., 116, A09301, doi:10.1029/2011JA016494. 1. Introduction field [Dwyer, 2003]. Because electric fields exceeding the RREA threshold field have been observed inside thunder- [2] In 1925, C. T.
    [Show full text]
  • Symposium Thunderstorms and Elementary Particle Acceleration (TEPA-2016)
    Symposium Thunderstorms and Elementary Particle Acceleration (TEPA-2016) GENERAL INFORMATION: TIME FRAME: October 3-7 2016 LOCATION: Nor Amberd International Conference Centre of the Yerevan Physics Institute, Byurakan, Aragatsotn District, Armenia. SYMPOSIUM WEBSITE: http://crd.yerphi.am/Conferences/tepa2016/home ORGANIZERS: Cosmic Ray Division of Yerevan Physics Institute, Armenia Skobeltsyn Institute of Nuclear Physics of Moscow State University, Russia INTERNATIONAL ADVISORY COMMITTEE: Ashot Chilingarian, Yerevan Physics Institute, Armenia, co-chair Lev Dorman, Israel Cosmic Ray Center and Emilio Segre' Observatory, Israel Joseph Dwyer, Space Science Center (EOS) and Department of Physics University of New Hampshire , USA Gerald Fishman, NASA-Marshall Space Flight Center, Huntsville, USA) Hartmut Gemmeke, Karlsruhe Institute of Technology, Germany David Smith, University of California, Berkeley Johannes Knapp, DESY Zeuthen, Germany Karel Kudela, Institute of Experimental Physics, Slovakia Alexandr Lidvanski, Nuclear Physics Institute, Russian Academy of Science, Russian Federation Jean Lilensten, Institut de Planétologie et d'Astrophysique de Grenoble, France Evgeny Mareev, Institute of Applied Physics, Nizhny Novgorod, Russian Federation Razmik Mirzoyan, MPI, Munich, Germany Yasushi Muraki, STE laboratory, Nagoya University, Japan Michail Panasyuk, Moscow State University, Russian Federation, co-chair Marco Tavani, INAF and University of Rome "Tor Vergata", Italy Tatsuo Torii, Japan Atomic Energy Agency, Tsuruga, Japan Harufumi Tsuchiya, Cosmic Radiation Laboratory, Riken, Japan. Lev Zeleny, Space Research Institute, Russian Academy of Sciences, Russian Federation BACKGROUND: The problem of thundercloud electrification and the mechanism of initiation of lightnings inside thunderclouds is one of the biggest unsolved problems in the atmospheric sciences. It is not yet understood how thundercloud electrification, lightning activity, wideband radio emission and particle fluxes relate to each other.
    [Show full text]
  • The Postdoc Summer 2013
    http://www7.national-academies.org/rap NRC Research Associateship Programs Newsletter Autumn 2011 RESEARCH ASSOCIATESHIP PROGRAMS The Postdoc Summer 2013 Table of Contents Meet Rebecca Rivera! NRC Representation at Autumn mtgs.. 2 Meet Rebecca Rivera! (cont) ………… 3 Vibrio Parahaemolyticus ………… 4-5 Meet Linda Sligh! ……………………. 5 Laser Cooling of Solids …………… 6-7 Optical Refrigeration to 119K … ... 8-10 Why Outreach Matters …………… 11 Dark Lightning Radiation ………..12-13 Space Traffic & Arctic Clouds …… 14 Nano-world Secrets ……………… 15 NRC RAP LinkedIn and Facebook… 16 Right: Rebecca Rivera, former DTRA/CBD NRC Associate, currently Laboratory Manager/ Research Scientist II, Marine Veterinary Virology Rebecca started working on her bachelor's degree at age 16 where she had the opportunity to work on a molecular genetics related project entitled “Reconstructing the Population History of Puerto Rico by Means of mtDNA Phy- logeographic Analysis.” In 2000 she was awarded a Travel Award to present her data at the 50th Annual Congress of the American Society of Human Genetics Project later published in the American Journal of Physical Anthropology. By age 20 she was accepted at U.C. DAVIS to do her Ph.D. in Com- parative Pathology with a pre-doctoral NIH grant. There her work was mainly immunology and virology re- lated. She focused on vaccine develop- ments for HIV-1, HCV and HPV. Rebecca graduated in 2006 and her Dissertation was “Immunogenic Properties of a Syn- Rebecca using biological hood Also see Scientific American “How Kitty is Kiling the Dolphins”: thetic Peptide Mixture Derived from the Hypervariable Regions of http://www.scientificamerican.com/article.cfm?id=pathogens-from Rebecca continued on page 3 -humans-cats-kill-seals-dolphins HIV-1 Envelope lycoprotein gp120”.
    [Show full text]
  • A Study of X-Ray Emission from Laboratory Sparks in Air at Atmospheric Pressure J
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, D23207, doi:10.1029/2008JD010315, 2008 Click Here for Full Article A study of X-ray emission from laboratory sparks in air at atmospheric pressure J. R. Dwyer,1 Z. Saleh,1 H. K. Rassoul,1 D. Concha,1 M. Rahman,2 V. Cooray,2 J. Jerauld,3,4 M. A. Uman,3 and V. A. Rakov3 Received 23 April 2008; revised 17 July 2008; accepted 25 September 2008; published 9 December 2008. [1] We present a detailed investigation of X-ray emission from long laboratory sparks in air at atmospheric pressure. We studied 231 sparks of both polarities using a 1-MV Marx generator with gap lengths ranging from 10 to 140 cm. The X rays generated by the discharges were measured using five NaI/PMT detectors plus one plastic scintillator/PMT detector, all enclosed in 0.32-cm-thick aluminum boxes. X-ray emission was observed to accompany about 70% of negative polarity sparks and about 10% of positive polarity sparks. For the negative sparks, X-ray emission was observed to occur at two distinct times during the discharge: (1) near the peak voltage, specifically, about 1 ms before the voltage across the gap collapsed, and (2) near the time of the peak current through the gap, during the gap voltage collapse. Using collimators we determined that the former emission emanated from the gap, while the latter appeared to originate from above the gap in the space over the high-voltage components. During individual sparks, the total energy of the X rays that was deposited in a single detector sometimes exceeded 50 MeV, and the maximum energy of individual photons in some cases exceeded 300 keV.
    [Show full text]
  • Terrestrial Gamma-Ray Flash Production by Lightning A
    TERRESTRIAL GAMMA-RAY FLASH PRODUCTION BY LIGHTNING A DISSERTATION SUBMITTED TO THE DEPARTMENT OF PHYSICS AND THE COMMITTEE ON GRADUATE STUDIES OF STANFORD UNIVERSITY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Brant E. Carlson October 2009 c Copyright by Brant E. Carlson 2010 All Rights Reserved ii I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. (Umran S. Inan) Principal Adviser I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. (Peter F. Michelson) Co-Adviser I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. (Elliott D. Bloom) I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. (Nikolai G. Lehtinen) Approved for the University Committee on Graduate Studies. iii iv Abstract Terrestrial gamma-ray flashes (TGFs) are brief flashes of gamma-rays originating in the Earth's atmosphere and observed by satellites. First observed in 1994 by the Burst And Transient Source Experiment on board the Compton Gamma-Ray Ob- servatory, TGFs consist of one or more 1 ms pulses of gamma-rays with a total ∼ fluence of 1 =cm2, typically observed when the satellite is near active thunder- ∼ storms.
    [Show full text]
  • 1 Runaway Breakdown and Electrical Discharges in Thunderstorms
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 115, XXXXXX, doi:10.1029/2009JA014818, 2010 1 Runaway breakdown and electrical discharges in thunderstorms 2 Gennady Milikh1 and Robert Roussel‐Dupré2 3 Received 22 August 2010; revised 2 August 2010; accepted 22 September 2010; published XX Month 2010. 4 [1] This review considers the precise role played by runaway breakdown (RB) in 5 the initiation and development of lightning discharges. RB remains a fundamental research 6 topic under intense investigation. The question of how lightning is initiated and 7 subsequently evolves in the thunderstorm environment rests in part on a fundamental 8 understanding of RB and cosmic rays and the potential coupling to thermal runaway 9 (as a seed to RB) and conventional breakdown (as a source of thermal runaways). In 10 this paper, we describe the basic mechanism of RB and the conditions required to initiate 11 an observable avalanche. Feedback processes that fundamentally enhance RB are 12 discussed, as are both conventional breakdown and thermal runaway. Observations 13 that provide clear evidence for the presence of energetic particles in thunderstorms/ 14 lightning include g‐ray and X‐ray flux intensifications over thunderstorms, g‐ray and 15 X‐ray bursts in conjunction with stepped leaders, terrestrial g‐ray flashes, and neutron 16 production by lightning. Intense radio impulses termed narrow bipolar pulses 17 (or NBPs) provide indirect evidence for RB particularly when measured in association 18 with cosmic ray showers. Our present understanding of these phenomena and their 19 enduring enigmatic character are touched upon briefly. 20 Citation: Milikh, G., and R. Roussel‐Dupré (2010), Runaway breakdown and electrical discharges in thunderstorms, 21 J.
    [Show full text]
  • University of California Santa Cruz Long Duration Gamma
    UNIVERSITY OF CALIFORNIA SANTA CRUZ LONG DURATION GAMMA-RAY EMISSION FROM THUNDERCLOUDS A dissertation submitted in partial satisfaction of the requirements for the degree of DOCTOR OF PHILOSOPHY in PHYSICS by Nicole A. Kelley December 2014 The Dissertation of Nicole A. Kelley is approved: Professor David M. Smith, Chair Professor Joseph R. Dwyer Professor Patrick Y. Chuang Dean Tyrus Miller Vice Provost and Dean of Graduate Studies Copyright c by Nicole A. Kelley 2014 Table of Contents List of Figures v List of Tables vii Abstract viii Dedication x Acknowledgments xi 1 Introduction 1 1.1 Electric fields inside thunderstorms . 2 1.2 Relativistic Runaway Electron Avalanches . 8 1.3 Gamma-ray Glow Observations . 13 1.4 High Energy Atmospheric Physics . 17 I Instrumentation 21 2 ADELE Instrument - Version 1.0 22 2.1 Instrumentation . 23 2.2 ADELE 2009 Campaign . 29 2.3 ADELE Calibrations . 36 2.3.1 Method 1 . 36 2.3.2 Method 2 . 39 2.3.3 Method Comparison . 42 3 ADELE Instrument - Version 2.0 44 3.1 New Instrument . 45 3.2 HS3 Mission . 47 iii 3.2.1 Testing . 48 3.2.2 Integration . 51 3.2.3 Mission . 52 3.3 Hurricane Hunters . 53 II Gamma Ray Glow Measurements 56 4 The ADELE Glows 57 4.1 Introduction . 57 4.2 Interpreting the ADELE Results . 59 4.3 Overview of the ADELE Glows . 61 4.4 Glows and their relationship to lightning . 68 4.4.1 The Glow Lightning Model . 76 5 Relativistic electron avalanches as a thunderstorm discharge com- peting with lightning 88 5.1 Introduction .
    [Show full text]
  • Investigations of Runaway Electron Generation, Transport, and Stability in the DIII-D Tokamak
    UC San Diego UC San Diego Electronic Theses and Dissertations Title Investigations of runaway electron generation, transport, and stability in the DIII-D tokamak Permalink https://escholarship.org/uc/item/8v07812x Author Tronchin-James, Alexander Nevil Publication Date 2011 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA, SAN DIEGO Investigations of runaway electron generation, transport, and stability in the DIII-D tokamak A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Engineering Science (Engineering Physics) by Alexander Nevil Tronchin-James Committee in charge: George Tynan, Chair C. Fred Driscoll Eric Hollmann Stefan Llewellyn Smith Richard Moyer Thomas O'Neil 2011 Copyright Alexander Nevil Tronchin-James, 2011 All rights reserved. The dissertation of Alexander Nevil Tronchin-James is approved, and it is acceptable in quality and form for publication on microfilm and electronically: Chair University of California, San Diego 2011 iii DEDICATION Dedicated to all the people who have treated me like family and made me feel at home, wherever I am. Also dedicated to the pursuit of flying motorcycles. iv EPIGRAPH Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover. {Mark Twain v TABLE OF CONTENTS Signature Page.................................. iii Dedication..................................... iv Epigraph.....................................v Table of Contents................................. vi List of Figures..................................x List of Tables................................... xvi Acknowledgements................................ xvii Vita.......................................
    [Show full text]