DOCSLIB.ORG

Shock Waves in Laser-Induced Plasmas

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Shock Waves in Laser-Induced Plasmas atoms Review Shock Waves in Laser-Induced Plasmas Beatrice Campanella, Stefano Legnaioli, Stefano Pagnotta , Francesco Poggialini and Vincenzo Palleschi * Applied and Laser Spectroscopy Laboratory, ICCOM-CNR, 56124 Pisa, Italy; [email protected] (B.C.); [email protected] (S.L.); [email protected] (S.P.); [email protected] (F.P.) * Correspondence: [email protected]; Tel.: +39-050-315-2224 Received: 7 May 2019; Accepted: 5 June 2019; Published: 7 June 2019 Abstract: The production of a plasma by a pulsed laser beam in solids, liquids or gas is often associated with the generation of a strong shock wave, which can be studied and interpreted in the framework of the theory of strong explosion. In this review, we will briefly present a theoretical interpretation of the physical mechanisms of laser-generated shock waves. After that, we will discuss how the study of the dynamics of the laser-induced shock wave can be used for obtaining useful information about the laser–target interaction (for example, the energy delivered by the laser on the target material) or on the physical properties of the target itself (hardness). Finally, we will focus the discussion on how the laser-induced shock wave can be exploited in analytical applications of Laser-Induced Plasmas as, for example, in Double-Pulse Laser-Induced Breakdown Spectroscopy experiments. Keywords: shock wave; Laser-Induced Plasmas; strong explosion; LIBS; Double-Pulse LIBS 1. Introduction The sudden release of energy delivered by a pulsed laser beam on a material (solid, liquid or gaseous) may produce a small (but strong) explosion, which is associated, together with other effects (ablation of material, plasma formation and excitation), with a violent displacement of the surrounding material and the production of a shock wave. The time evolution of a laser-induced shock wave and its geometry are dominated by the energy of the laser and the shape of the plasma generated. If the energy of the laser is delivered in a small spot, we may have spherical or hemispherical shock waves, while in case of elongated plasma (in liquids, for example) the shock wave may assume a cylindrical shape. Intermediate situations can be more complex (see Figure1). Atoms 2019, 7, 57; doi:10.3390/atoms7020057 www.mdpi.com/journal/atoms AtomsAtoms 20182019, 6, x, 7FOR, 57 PEER REVIEW 2 of 214 of 14 Figure 1. Spherical, hemispherical and cylindrical (with hemispherical caps) shock waves induced by a Figurelaser 1. in Spherical, a gas, solid hemispherical surface or inside and cylindrical a liquid. (with hemispherical caps) shock waves induced by a laser in a gas, solid surface or inside a liquid. The theoretical basis for the study of shock wave generation and propagation were laid by studies ofThe the blasttheoretical wave generatedbasis for inthe nuclear study explosions.of shock wave The studiesgeneration performed and propagation at Los Alamos were by Bethelaid by et al. studiesin 1941 of the [1] (publishedblast wave in generated a 1947 in in a reportnuclear then explosions. declassified The in studies 1958) and performed in UK by at the Los British Alamos physicist by BetheG. I.et Taylor al. in [19412] (published [1] (published in 1950) in evidenceda 1947 in a the report main then characteristics declassified of in a nuclear1958) and explosion in UK versusby the an Britishordinary physicist explosion, G. I. Taylor i.e., the [2] fact (published that the in energy 1950) isevidenced released inthe a main nuclear characteristics explosion in of a verya nuclear limited explosionvolume. versus The theoryan ordinary describing explosion, the blast i.e., the wave fact produced that the energy by a nuclear is released explosion in a nuclear is thus explosion the theory in aof very a point limited strong volume. explosion. The theory In Reference describing [1], thethe theoreticalblast wave treatment produced of by the a nuclear point strong explosion explosion is thuswas the developed theory of bya point John strong von Neumann. explosion. While In Re realizingference [1], the the di ffitheoreticalculties of treatment an exact treatment of the point of the strongshock explosion wave propagation, was developed von Neumann,by John von taking Neumann. into account While therealizing dimensions the difficulties of the explosion of an exact source, treatmentdemonstrated of the shock thata wave great propagation, simplification von of theNeumann, model cantaking be obtainedinto account by considering the dimensions the sourceof the of explosionenergy assource, a point. demonstrated that a great simplification of the model can be obtained by consideringIn this the approximation, source of energy a self-similar as a point. solution to the propagation of the shock waves can be searched for,In assumingthis approximation, a sudden release a self-similar of an energy solution E0 in to a negligiblethe propagation time and of volume. the shock waves can be searchedAssuming for, assuming an adiabatic a sudden expansion release of of an the energy (spherical) E0 in shocka negligible wave, time a purely and dimensionalvolume. reasoning leadsAssuming to the determinationan adiabatic expansion of the expansion of the (spheric law ofal) the shock shock wave, wave a as: purely dimensional reasoning leads to the determination of the expansion law of the shock wave as: !1/5 E R(t) = 0 / t2/5, (1) / () = K(γ)ρ0 , (1) () where R(t) is the radius of the shock wave at time t, ρ0 is the unperturbed density of the gas and K(γ) where R(t) is the radius of the shock wave at time t, is the unperturbed density of the gas and ()is ais constant a constant which which depends depends on the on adiabatic the adiabatic coefficient coefficient g of the g gas. of Similarthe gas. studies Similar were studies developed were in developedthe same in period the same in the period Soviet in Unionthe Soviet by L.I. Union Sedov. by L.I. Sedov. SedovSedov extended extended the theself-similar self-similar treatment treatment to stro to strongng explosions explosions produced produced by bylinear linear (cylindrical (cylindrical waves)waves) or planar or planar (plane (plane waves) waves) sources. sources. An Animmediate immediate generalization generalization of Equation of Equation (1) (1)to these to these shock shock wavewave geometries geometries leads leads to the to the expression: expression: /()!1/(2+α) () = E0 /()2/(2+, α) (2) R(t) =() t , (2) K(γ)ρ0 with α = 3 for spherical shock waves, α = 2 for cylindrical and α = 1 for plane shock waves. with α = 3 for spherical shock waves, α = 2 for cylindrical and α = 1 for plane shock waves. The work of Sedov, originally published in a Russian journal [3], later became available in the The work of Sedov, originally published in a Russian journal [3], later became available in the Western world (in 1959) with the publication of the famous book Similarity and Dimensional Methods Western world (in 1959) with the publication of the famous book Similarity and Dimensional Methods in Mechanics [4]. In fact, the description of the shock wave propagation is often referred to the Sedov– in Mechanics [4]. In fact, the description of the shock wave propagation is often referred to the Taylor point strong explosion theory. Sedov–Taylor point strong explosion theory. An interesting discussion on the limits of the Taylor approach, which obtained some popular success after the successful determination of the (classified) energy of the first atomic bomb tested in Atoms 2019, 7, 57 3 of 14 AtomsAn 2018, interesting 6, x FOR PEER discussionREVIEW on the limits of the Taylor approach, which obtained3 some of 14 popular success after the successful determination of the (classified) energy of the first atomic bomb tested in 19451945 inin thethe Nevada Nevada desertdesert (see(see Figure Figure2 ),2), is is reported reported by by Michael Michael A.B. A.B. Deakin Deakin in in Reference Reference [ 5 [5].]. According toAccording Deakin, Taylor’sto Deakin, calculation Taylor’s calculation of the Trinity of the bomb Trinity energy bomb [ 6energy] (which, [6] (which, in the word in the of word his biographer of his G.K. Batchelor,biographer causedG.K. Batchelor, him to becaused “mildly him to admonished be “mildly admonished by the USArmy by the forUS Army publishing for publishing his deductions his from deductions from their (unclassified) photographs” [7]) was indeed overestimated, although by a mere their (unclassified) photographs” [7]) was indeed overestimated, although by a mere 3% with respect 3% with respect to the calculations that could have been derived by the exact treatment of von toNeumann the calculations or Sedov. that could have been derived by the exact treatment of von Neumann or Sedov. Figure 2. 2. TheThe blast blast wave wave produced produced by bythethe first first nuclear nuclear test,test, 16 ms 16 after ms afterthe explosion. the explosion. The radius The radiusof of the the wave is about 200 m. (Trinity test, New Mexico 1945). wave is about 200 m. (Trinity test, New Mexico 1945). The critical point of the discussion is the evaluation of the K constant in Equation (1), which is a The critical point of the discussion is the evaluation of the K constant in Equation (1), which is function of the adiabatic coefficient γ of the gas in which the shock wave propagates. While the a function of the adiabatic coefficient γ of the gas in which the shock wave propagates. While the treatment of von Neumann and Sedov is exact, the determination of the K constant using Taylor’s treatmentapproach is of approximated. von Neumann One andshould Sedov consider, is exact, in any the case, determination that Equation (1) of always the K constantunderestimates using Taylor’s approachthe total energy is approximated.
Load more

Recommended publications
  • Radio Emissions Associated with Shock Waves and a Brief Model of Type Ii Solar Radio Bursts
    RADIO EMISSIONS ASSOCIATED WITH SHOCK WAVES AND A BRIEF MODEL OF TYPE II SOLAR RADIO BURSTS C. S. Wu¤ Abstract In this paper, we discuss the generation of radio waves at shock waves. Two cases are considered. One is associated with a quasi{perpendicular shock and the other is with a quasi{parallel shock. In the former case, it is stressed that a nearly perpendicular shock can lead to a fast Fermi acceleration. Looking at these energized electrons either in the deHo®mann{Teller frame or the plasma frame, one concludes that the accelerated electrons should inherently possess a loss{cone distribution after the mirror reflection at the shock. Consequently, these electrons can lead to induced emission of radio waves via a maser instability. In the latter case, we assume that a quasi{parallel shock is propagating in an environment which has already been populated with energetic electrons. In this case, the shock wave can also lead to induced radiation via a maser instability. Based on this notion, we describe briefly a model to explain the Type II solar radio bursts which is a very intriguing phenomenon and has a long history. 1 Introduction An interesting theoretical issue is how radio emission processes can be induced or triggered by shock waves under various physical conditions. In this article, we present a discussion which comprises two parts. The ¯rst part is concerned with a nearly perpendicular shock. In this case, the shock can energize a fraction of the thermal electrons or suprathermal electrons to much higher energies by means of a fast Fermi process.
    [Show full text]
  • Conventional Explosions and Blast Injuries 7
    Chapter 7: CONVENTIONAL EXPLOSIONS AND BLAST INJURIES David J. Dries, MSE, MD, FCCM David Bracco, MD, EDIC, FCCM Tarek Razek, MD Norma Smalls-Mantey, MD, FACS, FCCM Dennis Amundson, DO, MS, FCCM Objectives ■ Describe the mechanisms of injury associated with conventional explosions. ■ Outline triage strategies and markers of severe injury in patients wounded in conventional explosions. ■ Explain the general principles of critical care and procedural support in mass casualty incidents caused by conventional explosions. ■ Discuss organ-specific support for victims of conventional explosions. Case Study Construction workers are using an acetylene/oxygen mixture to do some welding work in a crowded nearby shopping mall. Suddenly, an explosion occurs, shattering windows in the mall and on the road. The acetylene tank seems to be at the origin of the explosion. The first casualties arrive at the emergency department in private cars and cabs. They state that at the scene, blood and injured people are everywhere. - What types of patients do you expect? - How many patients do you expect? - When will the most severely injured patients arrive? - What is your triage strategy, and how will you triage these patients? - How do you initiate care in victims of conventional explosions? Fundamental Disaster Management I . I N T R O D U C T I O N Detonation of small-volume, high-intensity explosives is a growing threat to civilian as well as military populations. Understanding circumstances surrounding conventional explosions helps with rapid triage and recognition of factors that contribute to poor outcomes. Rapid evacuation of salvageable victims and swift identification of life-threatening injuries allows for optimal resource utilization and patient management.
    [Show full text]
  • Characterizing Explosive Effects on Underground Structures.” Electronic Scientific Notebook 1160E
    NUREG/CR-7201 Characterizing Explosive Effects on Underground Structures Office of Nuclear Security and Incident Response AVAILABILITY OF REFERENCE MATERIALS IN NRC PUBLICATIONS NRC Reference Material Non-NRC Reference Material As of November 1999, you may electronically access Documents available from public and special technical NUREG-series publications and other NRC records at libraries include all open literature items, such as books, NRC’s Library at www.nrc.gov/reading-rm.html. Publicly journal articles, transactions, Federal Register notices, released records include, to name a few, NUREG-series Federal and State legislation, and congressional reports. publications; Federal Register notices; applicant, Such documents as theses, dissertations, foreign reports licensee, and vendor documents and correspondence; and translations, and non-NRC conference proceedings NRC correspondence and internal memoranda; bulletins may be purchased from their sponsoring organization. and information notices; inspection and investigative reports; licensee event reports; and Commission papers Copies of industry codes and standards used in a and their attachments. substantive manner in the NRC regulatory process are maintained at— NRC publications in the NUREG series, NRC regulations, The NRC Technical Library and Title 10, “Energy,” in the Code of Federal Regulations Two White Flint North may also be purchased from one of these two sources. 11545 Rockville Pike Rockville, MD 20852-2738 1. The Superintendent of Documents U.S. Government Publishing Office These standards are available in the library for reference Mail Stop IDCC use by the public. Codes and standards are usually Washington, DC 20402-0001 copyrighted and may be purchased from the originating Internet: bookstore.gpo.gov organization or, if they are American National Standards, Telephone: (202) 512-1800 from— Fax: (202) 512-2104 American National Standards Institute 11 West 42nd Street 2.
    [Show full text]
  • What Is a Quantum Shock Wave?
    What is a quantum shock wave? S. A. Simmons,1 F. A. Bayocboc, Jr.,1 J. C. Pillay,1 D. Colas,1, 2 I. P. McCulloch,1 and K. V. Kheruntsyan1 1School of Mathematics and Physics, University of Queensland, Brisbane, Queensland 4072, Australia 2ARC Centre of Excellence in Future Low-Energy Electronics Technologies, University of Queensland, Brisbane, Queensland 4072, Australia (Dated: November 4, 2020) Shock waves are examples of the far-from-equilibrium behaviour of matter; they are ubiquitous in nature, yet the underlying microscopic mechanisms behind their formation are not well understood. Here, we study the dynamics of dispersive quantum shock waves in a one-dimensional Bose gas, and show that the oscillatory train forming from a local density bump expanding into a uniform background is a result of quantum mechanical self- interference. The amplitude of oscillations, i.e., the interference contrast, decreases with the increase of both the temperature of the gas and the interaction strength due to the reduced phase coherence length. Furthermore, we show that vacuum and thermal fluctuations can significantly wash out the interference contrast, seen in the mean-field approaches, due to shot-to-shot fluctuations in the position of interference fringes around the mean. Introduction.—The study of dispersive shock waves in linear interaction [22], in both the GPE and NLSE, has been superfluids, such as dilute gas Bose-Einstein condensates exploited in, and is required for, the interpretation of disper- (BECs), has been attracting a growing attention in recent years sive shock waves as a train of grey solitons [6, 23]. However, (see, e.g., Refs.
    [Show full text]
  • Effect of a Small Dike on Blast Wave Propagation
    92 Yuta Sugiyama et al. Research paper Effect of a small dike on blast wave propagation Yu ta S u giyama＊†,Kunihiko Wakabayashi＊,Tomoharu Matsumura＊,andYoshioNakayama＊ ＊National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, JAPAN Phone : +81-29-861-0552 †Corresponding author : [email protected] Received : January 6, 2015 Accepted : March 31, 2015 Abstract This paper, by means of numerical simulations and experiments, investigates the effect of a small dike on the propagation of a blast wave so as to extract factors related to the strength of the blast wave on the ground. Three materials were considered in this study : detonation products, steel, and air. A cylindrical charge of pentaerythritol tetranitrate (PETN), with a diameter to height ratio of 1.0, was used in the experiments and numerical simulations. A steel dike surrounded the explosive charge on all sides. Its shape and size were parameters in this study. To elucidate the effect of the dike, we conducted two series of numerical simulations and experiments : one without a dike and one with a dike. Peak overpressures on the ground agreed with the experimental results. The numerical simulations qualitatively showed the effect of the three-dimensional diffraction and reflection of the blast wave at the dike, which affected the propagation behavior of the blast wave. Keywords : numerical simulation, experiment, blast wave, dike effect, directionalcharacteristics 1. Introduction interaction of the blast wave and a dike. We have been High-energetic materials yield powerful energy formulating our own numerical program, and in an early instantly, and are used widely in industrial technologies.
    [Show full text]
  • Arxiv:2103.05710V1 [Physics.Hist-Ph] 9 Mar 2021 Taylor Compared His Solution of the Evolution of the to Solve This Problem – Professor G
    Submitted to ANS/NT (2021) LA-UR-20-30042 (v3) On the Symmetry of Blast Waves Roy S. Baty (XTD-PRI)*and Scott D. Ramsey (XTD-NTA) Applied Physics Theoretical Design Division Los Alamos National Laboratory Abstract— This article presents a brief historical review of G. I. Taylor’s solution of the point blast wave problem which was applied to the Trinity test of the first atomic bomb. Lie group symmetry techniques are used to derive Taylor’s famous two-fifths law that relates the position of a blast wave to the time after the explosion and the total energy released. The theory of exterior differential systems is combined with the method of characteristics to demonstrate that the solution of the blast wave problem is directly related to the basic relationships that exist between the geometry (or symmetry) and the physics of wave propagation through the equations of motion. The point blast wave model is cast in terms of two exterior differential systems and both systems are shown to be integrable with local solutions for the velocity, pressure, and density along curves in space and time behind the blast wave. Endorsement: Len G. Margolin (XCP-5) I. HISTORICAL INTRODUCTION the Trinity test is 24:8 (±1:98) kilotons, which is pre- In 1950, the Proceedings of the Royal Society of Lon- sented in this issue by Selby, et al. [5]. Given the physical don published two papers by Sir Geoffrey Taylor [1] and complexity of the atomic explosion, the fact that Taylor’s [2]: the main purpose of these papers was to develop, blast wave solution accurately bounded and predicted the solve, and apply the results of a so-called point blast wave Trinity yield is remarkable.
    [Show full text]
  • Coronal Mass Ejections and Solar Radio Emissions
    CORONAL MASS EJECTIONS AND SOLAR RADIO EMISSIONS N. Gopalswamy∗ Abstract Three types of low-frequency nonthermal radio bursts are associated with coro- nal mass ejections (CMEs): Type III bursts due to accelerated electrons propagating along open magnetic field lines, type II bursts due to electrons accelerated in shocks, and type IV bursts due to electrons trapped in post-eruption arcades behind CMEs. This paper presents a summary of results obtained during solar cycle 23 primarily using the white-light coronagraphic observations from the Solar Heliospheric Ob- servatory (SOHO) and the WAVES experiment on board Wind. 1 Introduction Coronal mass ejections (CMEs) are associated with a whole host of radio bursts caused by nonthermal electrons accelerated during the eruption process. Radio bursts at low frequencies (< 15 MHz) are of particular interest because they are associated with ener- getic CMEs that travel far into the interplanetary (IP) medium and affect Earth’s space environment if Earth-directed. Low frequency radio emission needs to be observed from space because of the ionospheric cutoff (see Fig. 1), although some radio instruments permit observations down to a few MHz [Erickson 1997; Melnik et al., 2008]. Three types of radio bursts are prominent at low frequencies: type III, type II, and type IV bursts, all due to nonthermal electrons accelerated during solar eruptions. The radio emission is thought to be produced by the plasma emission mechanism [Ginzburg and Zheleznyakov, 1958], involving the generation of Langmuir waves by nonthermal electrons accelerated during the eruption and the conversion of Langmuir waves to electromagnetic radiation. Langmuir waves scattered off of ions or low-frequency turbulence result in radiation at the fundamental (or first harmonic) of the local plasma frequency.
    [Show full text]
  • Investigation of Shock Wave Interactions Involving Stationary
    Investigation of Shock Wave Interactions involving Stationary and Moving Wedges Pradeep Kumar Seshadri and Ashoke De* Department of Aerospace Engineering, Indian Institute of Technology Kanpur, Kanpur, 208016, India. *Corresponding Author: [email protected] Abstract The present study investigates the shock wave interactions involving stationary and moving wedges using a sharp interface immersed boundary method combined with a fifth-order weighted essentially non- oscillatory (WENO) scheme. Inspired by Schardin’s problem, which involves moving shock interaction with a finite triangular wedge, we study influences of incident shock Mach number and corner angle on the resulting flow physics in both stationary and moving conditions. The present study involves three incident shock Mach numbers (1.3, 1.9, 2.5) and three corner angles (60°, 90°, 120°), while its impact on the vorticity production is investigated using vorticity transport equation, circulation, and rate of circulation production. Further, the results yield that the generation of the vorticity due to the viscous effects are quite dominant compared to baroclinic or compressibility effects. The moving cases presented involve shock driven wedge problem. The fluid and wedge structure dynamics are coupled using the Newtonian equation. These shock driven wedge cases show that wedge acceleration due to the shock results in a change in reflected wave configuration from Single Mach Reflection (SMR) to Double Mach Reflection (DMR). The intermediary state between them, the Transition Mach Reflection (TMR), is also observed in the process. The effect of shock Mach number and corner angle on Triple Point (TP) trajectory, as well as on the drag coefficient, is analyzed in this study.
    [Show full text]
  • Interstellar Heliospheric Probe/Heliospheric Boundary Explorer Mission—A Mission to the Outermost Boundaries of the Solar System
    Exp Astron (2009) 24:9–46 DOI 10.1007/s10686-008-9134-5 ORIGINAL ARTICLE Interstellar heliospheric probe/heliospheric boundary explorer mission—a mission to the outermost boundaries of the solar system Robert F. Wimmer-Schweingruber · Ralph McNutt · Nathan A. Schwadron · Priscilla C. Frisch · Mike Gruntman · Peter Wurz · Eino Valtonen · The IHP/HEX Team Received: 29 November 2007 / Accepted: 11 December 2008 / Published online: 10 March 2009 © Springer Science + Business Media B.V. 2009 Abstract The Sun, driving a supersonic solar wind, cuts out of the local interstellar medium a giant plasma bubble, the heliosphere. ESA, jointly with NASA, has had an important role in the development of our current under- standing of the Suns immediate neighborhood. Ulysses is the only spacecraft exploring the third, out-of-ecliptic dimension, while SOHO has allowed us to better understand the influence of the Sun and to image the glow of The IHP/HEX Team. See list at end of paper. R. F. Wimmer-Schweingruber (B) Institute for Experimental and Applied Physics, Christian-Albrechts-Universität zu Kiel, Leibnizstr. 11, 24098 Kiel, Germany e-mail: [email protected] R. McNutt Applied Physics Laboratory, John’s Hopkins University, Laurel, MD, USA N. A. Schwadron Department of Astronomy, Boston University, Boston, MA, USA P. C. Frisch University of Chicago, Chicago, USA M. Gruntman University of Southern California, Los Angeles, USA P. Wurz Physikalisches Institut, University of Bern, Bern, Switzerland E. Valtonen University of Turku, Turku, Finland 10 Exp Astron (2009) 24:9–46 interstellar matter in the heliosphere. Voyager 1 has recently encountered the innermost boundary of this plasma bubble, the termination shock, and is returning exciting yet puzzling data of this remote region.
    [Show full text]
  • Evaluation and Treatment of Blast Injuries
    9/4/2014 Blast Injuries Objectives • An Overview of the Effects of Blast Injuries at the • Describe the basic physics, mechanisms of injury, and Medical Level pathophysiology of blast injury • List the four types or categories of blast injuries • List the factors associated with increased risk of Presented by: Jay Wuerker, EMT-P primary blast injury EMS Instructor II Objectives…cont. Why? • Recognize the key diagnostic indicators of serious • Combat primary blast injury • Terrorism • State the most common cause of death following an • Accidents explosion Combat: Iraq & Afghanistan Terrorism: USS Cole 1 9/4/2014 Terrorism: ??? Terrorism • Bombings are clearly the most common cause of casualties in terrorist incidents. • Recent terrorism has shown increasing numbers of suicidal bombers wearing or driving the explosive device • A poor man’s guided missile! Boston Marathon April 15, 2013 Pressure cooker device • Pressure cooker device (2), form of an IED • “Inspire” magazine Summer 2010, “Make a Bomb in • Same type of device used in Mumbai train bombings the Kitchen of your Mom”, by “The AQ chef”. in 2006 and Time Square car bomb attempt in 2010 • Al-Qaeda publication article on the step by step • Often packed with nails, ball bearings and other small process for making a Pressure cooker bomb. metal objects Boston Marathon Results • Three killed, 264 wounded – many with amputations, scene described as a war zone • One Police officer killed in shoot out with bomber suspect Dzhokhar Tsarnaev 2 9/4/2014 Not in Wisconsin? • Steve Preisler - aka “Uncle Fester” , from Green Bay , graduated from Marquette University in 1981 with a degree in Chemistry and Biology.
    [Show full text]
  • Observing Stellar Bow Shocks
    Observing stellar bow shocks A.C. Sparavigna a and R. Marazzato b a Department of Physics, Politecnico di Torino, Torino, Italy b Department of Control and Computer Engineering, Politecnico di Torino, Torino, Italy Abstract For stars, the bow shock is typically the boundary between their stellar wind and the interstellar medium. Named for the wave made by a ship as it moves through water, the bow shock wave can be created in the space when two streams of gas collide. The space is actually filled with the interstellar medium consisting of tenuous gas and dust. Stars are emitting a flow called stellar wind. Stellar wind eventually bumps into the interstellar medium, creating an interface where the physical conditions such as density and pressure change dramatically, possibly giving rise to a shock wave. Here we discuss some literature on stellar bow shocks and show observations of some of them, enhanced by image processing techniques, in particular by the recently proposed AstroFracTool software. Keywords : Shock Waves, Astronomy, Image Processing 1. Introduction Due to the presence of space telescopes and large surface telescopes, equipped with adaptive optics devices, a continuously increasing amount of high quality images is published on the web and can be freely seen by scientists as well as by astrophiles. Among the many latest successes of telescope investigations, let us just remember the discovery with near-infrared imaging of many extra-solar planets, such as those named HR 8799b,c,d [1-3]. However, the detection of faint structures remains a challenge for large instruments. After high resolution images have been obtained, further image processing are often necessary, to remove for instance the point-spread function of the instrument.
    [Show full text]
  • 00320773.Pdf
    LA-2000 PHYSICS AND MATHEMATICS (TID-4500, 13th ed., Supp,.) LOS ALAMOS SCIENTIFIC LABORATORY OF THE UNIVERSITY OF CALIFORNIA LOS ALAMOS NEW MEXICO REPORT WRITTEN: August 1947 REPORT DISTRIBUTED: March 27, 1956 BLAST WAVE’ Hans A. Bethe Klaus Fuchs Joseph 0. Hirxhfelder John L. Magee Rudolph E. Peierls John van Neumann *This report supersedes LA-1020 and part of LA-1021 =- -l- g$g? ;-E Contract W-7405-ENG. 36 with the U. S. Atomic Energy Commission m 2-0 This report is a compilation of the dedassifid chapters of reports LA.-IO2O and LA-1021, which 11.a.sbeen published becWL’3eof the demnd for the hfcmmatimo with the exception d? CaM@mr 3, which was revised in MN& it reports early work in the field of blast phencmma. Ini$smw’$has the authors had h?ft the b$ Ala.mos kb(mktm’y Wkll this z%po~ was compiled, -they have not had ‘the Oppxrtl.mity to review their [email protected] and make mx.m%xtti.cms to reflect later tiitii~e ., CONTENTS Page Chapter I INTRODUCTION, by Hans A. Bethe 11 1.1 Areas of Discussion 11 1.2 Comparison of Nuclear and Ordinary Explosion 11 1.3 The Sequence of Events in a Blast Wave Produced by a Nuclear Explosion 13 1.4 Radiation 16 1.5 Reflection of Blast Wave, Altitude Effect, etc. 21 1.6 Damage 24 1.7 Measurements of Blast 26 Chapter 2 THE POINT SOURCE SOLUTION, by John von Neumann 27 2.1 Introduction 27 2.2 Analytical Solution of the Problem 30 2.3 Evaluation and Interpretation of the Results 46 Chapter 3 THERMAL RADIATION PHENOMENA, by John L.
    [Show full text]