DOCSLIB.ORG

United States Patent (19) 11) 4,156,852 Hagen (45) May 29, 1979

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
United States Patent (19) 11) 4,156,852 Hagen (45) May 29, 1979 United States Patent (19) 11) 4,156,852 Hagen (45) May 29, 1979 54 MULTIPASS LASER AMPLIFICATION 4,093,924 6/1978 Farcy .................................... 330/4.3 WITH NEAR-FELD FAR-FELD OPTICAL OTHER PUBLICATIONS SEPARATION Hunt et al., “The Use of Multiple Spatial Felters as a 75) Inventor: Wilhelm F. Hagen, Livermore, Calif. Relay Line in Laser Fusion Systems', 9/9/76, pp. 1-7, 73) Assignee: The United States of America as Preprint 78653, Lawrence Livermore Laboratory. represented by the United States Primary Examiner-Nelson Moskowitz Department of Energy, Washington, Attorney, Agent, or Firm-Roger S. Gaither; P. Martin D.C. Simpson; John F. Schipper 21 Appl. No.: 868,640 57 ABSTRACT 22 Filed: Jan. 11, 1978 This invention discloses two classes of optical configu rations for high power laser amplification, one allowing 51) int. Cl’................................................ H01S 3/08 near-field and the other allowing far-field optical sepa 52 U.S. C. ................................. 330/4.3; 331/94.5 C ration, for the multiple passage of laser pulses through 58) Field of Search .................... 330/4.3; 331/94.5 C, one or more amplifiers over an open optical path. These 356/106 LR configurations may reimage the amplifier or any other (56) References Cited part of the cavity on itself so as to suppress laser beam U.S. PATENT DOCUMENTS intensity ripples that arise from diffraction and/or non linear effects. The optical cavities combine the features 3,247,467 4/1966 Geusic et al. ... 330/4.3 of multiple passes, spatial filtering and optical reimaging 3,258,717 6/1966 Katzman ....... ... 330/4.3 3,585,523 6/1971 Glenn et al. ...... 331/94.5 C and allow sufficient time for laser gain recovery. 3,942,127 3/1976 Fluhr et al. ........................... 330/4.3 4,001,705 1/1977 Sinclair et al. .................. 331/94.5 C 36 Claims, 5 Drawing Figures U.S. Patent May 29, 1979 Sheet 1 of 3 4,156,852 M4 KS) &S3%2147 F34 &(SXS %2 & 22 SA-F2 PM2 Mo 3. 2 NS 2,SX2 XVZ... 2. 2 P2 -- X NZ U.S. Patent May 29, 1979 Sheet 3 of 3 4,156,852 twin aaaaaaaaaaaaaaaaaaaaaaaaaaaa. 4,156,852 1. 2 generative amplifier and being driven by a low power MULTIPASS LASER AMPLFICATION WITH oscillator, with the amplifier gain just below the thresh NEAR-FELD FAR-FELD OPTICAL SEPARATION old for oscillation. The gain medium of this traveling wave regenerative amplifier is driven in only one direc BACKGROUND OF THE INVENTION tion around the ring and requires slaving the resonant The invention described herein arose at the Law frequency of the ring interferometer to the oscillator, rence Livermore Laboratory, University of California, which should have spectrally pure output. in the course of or under contract W-7405-ENG-48 U.S. Pat. No. 3,414,835 to Miller, teaches and claims with the U.S. Department of Energy. the use of a closed path optical system to cause an in The use of multipass amplifiers is potentially attrac 10 jected laser pulse to be multiply reflected from two or tive in laser generation of high density and high temper more surfaces and to be periodically focused and refo ature plasmas as it reduces the number of amplifiers cused so that the light beam passes through a transpar required in an amplifier chain and thus reduces the cost ent work piece or sample many times. No provision is and complexity of the associated laser system while made for rapidly and repetitively amplifying the laser increasing the overall system efficiency. Up to 35% of 15 the stored energy can be extracted efficiently from a pulse each time it traverses the optical system or for conventional single pass laser amplifier in a short pulse, positioning the target in the cavity. due to the flux limitations caused by damage of optical U.S. Pat. No. 3,668,536 to Michon teaches the use of components and due to depletion of the population a single amplifier with fully reflective means spaced inversion in the two energy levels used for amplifica 20 from the ends of the amplifier, to reflect light back into tion. Multiple passes through an amplifier can double the amplifier and cause the amplifier to respond as if it the extracted energy, provided that sufficient time be were several amplifier stages in series. Pulse switchout tween passes is allowed for laser gain recovery through means is also provided. Michon is forced to shorten his decay of the lower laser level or by other processes. pulse initally, to avoid overlap between counterpropa A number of requirements are essential in any high 25 gating portions of the same pulse; and Michon does not power laser amplifier chain design. Spatial filtering indicate how his amplifier stages might be repetitively between amplifier passes is necessary to reduce the pumped or how laser beam intensity ripples might be growth of small scale intensity ripples on the beam, suppressed as the beam traverses the optical cavity. arising from non-linear effects. Reimaging of the beam Welch, in U.S. Pat. No. 3,968,456, teaches and claims on itself or beam optical relaying from one amplifier to 30 the use of an optical cavity, containing two plane mir the next is desirable to avoid large scale beam intensity rors, two lenses and an amplifier, together with an ex ripples due to diffraction and/or non-linear effects. For ternal collimating lens for "directing' an external light the multipass configurations considered here, it is im beam into the cavity, in a regenerative laser device. The portant to keep the cavity losses as low as possible. Use external lens is positioned adjacent and parallel to one of optical components that do not contribute to non-lin 35 of the cavity mirrors and is spaced a distance equal to ear beam distortion is preferable so that, ceteris paribus, external lens focal length from the adjacent mirror. The use of mirrors is preferable to the use of lenses. In mul adjacent mirror is a highly transparent one, transmitting tipass configurations with spatial filters it is essential to approximately 90% of the radiation incident thereon allow time for dispersal of any plasma blowoff gener from within the cavity. The Welch invention serves as ated at a spatial filter aperture. Estimates of the dis a highly sensitive amplifier or sensor of radiation inci persal time for such a plasma correspond to a path dent upon the external lens, with the optical cavity length of several kilometers, which would significantly amplifier being excited to just below threshold for laser increase the cost of a multipass system with a single operation, but the configuration is not particularly use pinhole. The use of several, sequentially used spatial ful for a high power laser system. The cavity lenses 8, 12 filters allows selection of different aperture sizes and 45 of Welch cause the light beam to converge as the beam associated cutoff frequencies of the intensity ripples in passes through the amplifier so that the fill factor and the laser beam. maximum gain are reduced. Further, the use of a highly Multipass and/or regenerative amplifiers have been transmissive mirror 14 defining one end of the cavity known for many years but have never been applied in would be detrimental in the multipass configuration the present context. U.S. Pat. No. 3,597,695 to Swain et 50 employed in the subject invention. all teaches and shows use of one or more passes of a laser A "Long Path Laser' was built at Lawrence Liver pulse through a single amplifier placed inside an optical more Laboratory to provide nine passes of a laser beam cavity for laser amplification. The (polarized) laser through a disk amplifier over an open optical path. As pulses are injected into the cavity, which contains the shown in Lawrence Livermore Laboratory Report amplifier and two mirrors spaced therefrom, and are 55 UCRL-50021-71 Rev. 1 pp. 24-27. The beam was not allowed to pass one or more times through the amplifier focused between any of the 9 passes, and the energy before being switched out of the cavity by polarity output was only 200 Joules. control using a Pockels cell. The amplifier is excited Past attempts to use regenerative amplifiers have only once, and the energy output of the amplifier is been limited by the switch-out phase after laser beam limited by damage to the weakest component, which is amplification by diffraction effects, and by non-linear the Pockels cell. Swain et al, appears to contemplate optics. As shown in the Long Path Laser, no switch is only the use of a relatively long lifetime gain medium, needed in an open optical path. As laser beam energy such as Nd:glass, where multiple excitation of the gain increases, the switch becomes a limiting element in the medium is unnecessary. Multiple excitation of the am laser. In the Miller patent, the laser beam is focused on plifier medium and switching techniques implying other 65 to a workpiece, but Miller does not address the diffrac means than a Pockel cell are not described. tion and non-linear optics problems. In none of these U.S. Pat. No. 3,646,469 to Buczek et all teaches and patents is a spatial filter or an optical relay suggested. claims the use of a ring interferometer, acting as a re Design difficulties regarding beam quality of a laser 4,156,852 3 4. beam exiting on open optical paths are not solved in the DETAILED DESCRIPTION above art.
Load more

Recommended publications
  • Long Path Laser Spectroscopy of Weak
    LONG PATH LASER SPECTROSCOPY OF WEAK SPECTRAL TRANSITIONS IN PLASMAS A Thesis Submitted for the Degree of DOCTOR OF PHILOSOPHY In the UNIVERSITY OF LONDON By MARK PHILIP SYDNEY NIGHTINGALE The Blackett Laboratory Imperial College of Science and Technology London SW7 2BZ LONG PATH LASER SPECTROSCOPY OF WEAK SPECTRAL TRANSITIONS IN PLASMAS By MARK PHILIP SYDNEY NIGHTINGALE ABSTRACT There has been much interest recently in spectral lineshapes, especially in plasmas where charge particle broadening is important. For the accurate measurement of such profiles, absorption spectroscopy offers distinct advantages over other techniques but requires the use of long optical paths (several metres or more) since, typically, plasma opacities are extremely low. A z-pinch plasma device has been used to generate a 10 metre long plasma column and optical paths in this plasma exceeding one kilometre have been achieved by the use of a multipassed CW dye laser system. Such paths allow both the accurate measurement of allowed line profiles over five orders of magnitude of absorption, and also provide the means of measuring weak features such as forbidden lines or continua. Full electron density diagnostics have been performed using interferometry (over twenty-one metre paths) and these show considerable density oscillations during the plasma recombination phase whose origins and effects might have considerable importance in the use of plasmas as spectroscopic sources. Results are presented for several long path absorption and 3 1 interferometric experiments. In Helium the 2p P - 3d 'D forbidden intercombination satellite on the 5876 A line-wing is fully resolved providing evidence as to its origin.
    [Show full text]
  • PROTO-SPHERA Confines Axisymmetric Plasma Tori in Absence of Any Toroidal Magnet and Just in Presence of a Static Poloidal Magnetic Field
    PROTO-SPHERA confines axisymmetric plasma tori in absence of any toroidal magnet and just in presence of a static poloidal magnetic field FSN Department, CR-ENEA Frascati Franco Alladio, Paolo Micozzi, Fabrizio Andreoli, Gerarda Apruzzese, Luca Boncagni, Paolo Buratti, Fabio Crescenzi, Ocleto D’Arcangelo, Giuseppe Galatola Teka, Edmondo Giovannozzi, Andrea Luigi Grosso, Matteo Iafrati, Alessandro Lampasi, Violeta Lazic, Simone Magagnino, Valerio Piergotti, Mario Pillon, Selanna Roccella, Giuliano Rocchi, Alessandro Sibio, Benedetto Tilia, Onofrio Tudisco, Alessandro Mancusoretired , Vincenzo Zanzaretired FSN Department, CR-ENEA Frascati and CREATE Consortium Giuseppe Maffia, Brunello Tirozzi, PlasmaTech Spin-off of Pisa University Francesco Giammanco, Paolo Marsili Pisa University Danilo Giulietti Nature Physics (2018) 1 Abstract The PROTO-SPHERA experiment, using DC helicity injection driven by a voltage applied between electrodes, has formed and sustained up to ½ sec magnetically confined current carrying tori in presence of a pre-existing axisymmetric configuration of magnetostatic poloidal field only and in absence of any doubly connected toroidal magnet. This result provides the first hints that future Fusion machines could be built with permanent magnets only. The relevance of a magnetic confinement machine built by axisymmetric permanent magnets only The use of permanent magnets in toroidal plasma confinement would be paramount for simplifying the design and the complexity of a Controlled Fusion rector based upon magnetic confinement. It would remove any direct dissipation connected with currents flowing inside the magnetic field coils and would even have great advantages with respect to superconducting coils, which share with permanent magnets the absence of ohmic dissipation but require a sophisticated cryogenic system; such a system entails a number of other thermal dissipations, in order to maintain the superconducting coils at the required low temperature conditions.
    [Show full text]
  • Optical Diagnostics Applied on Proto-Sphera Plasmas Thursday, 4 October 2018 14:30 (1H 30M)
    ICFDT5 - 5th International Conference on Frontier in Diagnostic Technologies Contribution ID: 18 Type: Poster Optical diagnostics applied on Proto-Sphera plasmas Thursday, 4 October 2018 14:30 (1h 30m) Proto-Sphera is an innovative plasma confinement concept based on the formation of a toroidal plasma around an axial screw pinch which provides the toroidal magnetic field. Optical emission (OE) from the Proto-Sphera device is detected by a compact spectrometer array covering the range 235-790 nm with the resolution from 0.09 nm in UV to 0.14 nm in IR. Plasmas formed in both Argon and Hydrogen gases are studied. The spectra are registered each 5 ms in order to study the time evolution of different species in the plasma that include H I, O I, Cu I and Cu II coming from the cathode erosion, C I present due to the wall erosion, and Ar I to Ar III in case of the discharge in argon environment. Simultaneously, the transmitted intensity of a collimated He-Ne laser beam, crossing the chamber towards the detection system, is also monitored. The optical system is equipped with a variable focusing in order to collect the signal mainly from the reactor’s center (R = 0) or at distances from the center up to the plasma edge (R≈ -30 cm). In presence of the plasma, which is almost spherical around the reactor’s center, the detected He-Ne line intensity increases, likely because of the radial distribution of the electron density, having a peak at the center, as confirmed by the spatially resolved OE spectroscopy.
    [Show full text]
  • Biennial Report 1999/2000
    INSTITUTE FOR TROPOSPHERIC RESEARCH WISSENSCHAFTSGEMEINSCHAFT BiennialBiennial GOTTFRIED WILHELM LEIBNIZ ReportReport 1999/2000 Biennial Report 11999999 & 22000000 INSTITUTE FOR TROPOSPHERIC RESEARCH WISSENSCHAFTSGEMEINSCHAFT GOTTFRIED WILHELM LEIBNIZ Impressum Impressum Published by Institute for Tropospheric Research (IfT) Institut für Troposphärenforschung e.V. Leipzig (IfT) Member of the Wissenschaftsgemeinschaft Gottfried Wilhelm Leibniz (WGL) Postal address: Permoserstr. 15 Phone: ++49 - 341-235-2321 04318 Leipzig Fax: ++49 - 341-235-2361 Germany E-mail: [email protected] Internet: http://www.tropos.de Editors Konstanze Kunze, Andrea Mehlhose, Katja Schmieder, Monika Schulze Editorial Board Jost Heintzenberg, Hartmut Herrmann, Eberhard Renner Technical management / DTP / Layout Katja Schmieder Printed by MERKUR Druck- und Kopierzentrum GmbH Hauptmannstraße 4 04109 Leipzig Internet: http://www.merkurdruck.de Photo and illustration credits © IfT; all pages, except for pages: 12: courtesy of A. Petzold, Deutsches Zentrum für Luft- und Raumfahrt (DLR) 53: Archives: Sächsisches Landesamt für Umwelt und Geologie, G.Engler ”Kahleberg - (LSG Osterzgebirge) - 10/1996“. Table of contents Introduction and Overview 3 Detailed contributions to current research projects N Lindenberg Aerosol Characterization Experiment 1998 (LACE98) 11 N Indian Ocean Experiment (INDOEX) 15 N Size segregated characterization of fi ne particulate matter in Leipzig and Melpitz 27 N Multiphase modeling and laboratory studies 34 N The micro-scale meteorological model
    [Show full text]
  • Technical Note: Formal Blind Intercomparison of OH Measurements: Results from the International Campaign Hoxcomp
    University of Wollongong Research Online Faculty of Science, Medicine and Health - Papers: part A Faculty of Science, Medicine and Health 1-1-2009 Technical note: Formal blind intercomparison of OH measurements: results from the international campaign HOxComp E Schlosser Forschungszentrum Julich, Gemany T Brauers Forschungszentrum Julich, Gemany H -P Dorn Forschungszentrum Julich, Gemany H Fuchs Forschungszentrum Julich, Gemany R Haseler Forschungszentrum Julich, Gemany See next page for additional authors Follow this and additional works at: https://ro.uow.edu.au/smhpapers Part of the Medicine and Health Sciences Commons, and the Social and Behavioral Sciences Commons Recommended Citation Schlosser, E; Brauers, T; Dorn, H -P; Fuchs, H; Haseler, R; Hofzumahaus, A; Holland, F; Wahner, A; Kanaya, Yugo; Kajii, Y; Miyamoto, K; Nishida, S; Watanabe, K; Yoshino, A; Kubistin, Dagmar; Martinez, M; Rudolf, M; Harder, H; Berresheim, H; Elste, T; Plass-Dulmer, C; Stange, G; and Schurath, U, "Technical note: Formal blind intercomparison of OH measurements: results from the international campaign HOxComp" (2009). Faculty of Science, Medicine and Health - Papers: part A. 1826. https://ro.uow.edu.au/smhpapers/1826 Research Online is the open access institutional repository for the University of Wollongong. For further information contact the UOW Library: [email protected] Technical note: Formal blind intercomparison of OH measurements: results from the international campaign HOxComp Abstract Hydroxyl radicals (OH) are the major oxidizing species in the troposphere. Because of their central importance, absolute measurements of their concentrations are needed to validate chemical mechanisms of atmospheric models. The extremely low and highly variable concentrations in the troposphere, however, make measurements of OH difficult.
    [Show full text]
  • 1-D Modeling of the Screw-Pinch Plasma in PROTO-SPHERA
    fluids Article 1-D Modeling of the Screw-Pinch Plasma in PROTO-SPHERA Paolo Buratti 1,* , Brunello Tirozzi 1,2,3, Franco Alladio 1 and Paolo Micozzi 1 1 ENEA, Fusion and Nuclear Safety Department, C. R. Frascati, Via E. Fermi 45, 00044 Frascati (Roma), Italy; [email protected] (B.T.); [email protected] (F.A.); [email protected] (P.M.) 2 Consorzio CREATE, Università di Napoli Federico II, Via Claudio 21, 80125 Napoli, Italy 3 Department of Physics, University La Sapienza of Rome, 00185 Roma, Italy * Correspondence: [email protected] Received: 25 January 2019; Accepted: 4 March 2019; Published: 7 March 2019 Abstract: A simple steady-state model for a 3-species mixture (ions, electrons, and neutrals) in a screw-pinch plasma configuration is developed. The model is applied to the central plasma column of the PROTO-SPHERA experiment. Degree of ionization, azimuthal current density, and azimuthal ion velocity are calculated. Full ionization is found at plasma temperatures above 1.5 eV, with neutrals confined in an outer shell where radial plasma flow develops and drives both azimuthal current and azimuthal flow. Keywords: PROTO-SPHERA; plasma confinement; plasma diffusion; plasma spontaneous rotation 1. Introduction Magnetically confined plasmas are commonly formed inside a toroidal vacuum vessel surrounded by a toroidal magnet. Plasma-facing components and conductors are subject to severe thermal, nuclear, and electromechanical loads at the inboard side of the torus. To give a proof of principle of a magnetic confinement configuration which can overcome this problem, the PROTO-SPHERA project [1,2] is aimed at producing hot toroidal plasma in a simply connected machine topology, i.e., without solid elements between the plasma and the symmetry axis.
    [Show full text]
  • State of the Art of Technologies for Remote Detection of Natural Gas
    Report SGC 110 STATE OF THE ART OF TECHNOLOGIES FOR REMOTE DETECTION OF NATURAL GAS ©Swedish Gas Center - June 2000 Sven-Åke Ljungberg - Editor THE SWEDISH ROYAL INSTITUTE OF TECHNOLOGY, SWEDEN Thomas Kulp SANDIA NATIONAL LABORATORY, USA Hideo Tai JAPAN GAS ASSOCIATION, JAPAN Gretta Akopova VNIIGAZ, RUSSIA Report SGC 110 ISSN 1102-7371 ISRN SGC-R--110--SE FOREWORD RD&D-projects performed by the Swedish Gas Centre are usually presented in reports, available to each and everyone who wants to share the results of a project. SGC prints and publishes the reports but the authors of each report are responsible for the accuracy of the content. Everyone making use of any descrip0tion, results etc, will do this on his own responsibility. Excerpts from a report may be used if the source is indicated. Swedish Gas Centre (SGC is a joint venture of energy gas business organisations. SGC’s primary mission is to co-ordinate the joint Research Development and Demonstration (RD&D) efforts that are performed within the Swedish gas industry. The shareholders of SGC are: The Swedish Gas Association, Sydgas AB, Sydkraft AB, Gothenburg Energy, Lund Energy and Helsingborg Energy. This project as been funded by: The Swedish National Energy Administration Gas Research Institute, USA Japan Gas Association, Japan BG Technology, Great Britain Gasunie N.V. Nederlanse, Holland Gas du France, France Danskt Gastekniskt Center, Denmark NSR, Sweden VNIIGAZ, Russia Sydgas Vattenfall Naturgas AB Göteborg Energi AB Birka Energi AB Helsingborg Energi AB Lunds Energi AB SVENSKT GASTEKNISKT CENTER AB Johan Rietz Summary and conclusions There is an increasing awareness of the need to detect and survey gaseous fugitive emissions from production and distribution systems, industrial and energy processes, transportation systems for dangerous goods, leaks from landfill bodies, and from natural sources.
    [Show full text]
  • Report on the Hox Workshop 2015 Held in Juelich
    Assessment of local HOx and ROx Measurement Techniques: Achievements, Challenges, and Future Directions Report of the International HOx Workshop 2015 Organisers Andreas Hofzumahaus and Dwayne Heard Hosted by Forschungszentrum Jülich 23‐25 March 2015 Editors Andreas Hofzumahaus Instittut für Energie und Klimaforschung: Troposphäre (IEK‐8), Forschungszentrum Jülich, 52425 Jülich, Germany, a.hofzumahaus@fz‐juelich.de Dwwayne Heard School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK, and National Centre for Atmospheric Science, University of Leeds, Leeds, LS2 9JT, UK, [email protected] Endorsed Workshop Forschungszentrum Jülich May 2016 ii Preface Measurements of HOx and ROx radicals are an important tool for the investigation of tropospheric chemistry in field campaigns and simulation chamber experiments. The measured data allow us to test chemical models simulating the atmospheric concentrations of OH, HO2 and RO2, and help to improve chemical mechanisms used in regional and global models for predictions of the atmospheric chemical composition. Even after four‐decades of development and application of radical measurement techniques, accurate measurement of radical species remains a highly challenging task and requires persistent care. From March 23‐25 2015, an international, IGAC‐endorsed workshop took place at JUFA, Jülich, and hosted by the Forschungszentrum Jülich, Germany, to assess the performance and reliability of current HOx measurement techniques. Fifteen international groups from Germany, UK, Ireland, France, Finland, USA, China and Japan came together to discuss achievements, challenges and future directions of techniques based on laser absorption and laser‐induced fluorescence spectroscopy, chemical ionisation mass spectrometry, and chemical techniques. There were 35 participants at the workshop, including Principal Investigators, Postdoctoral Fellows and Postgraduate Students, with representatives from virtually all groups world‐wide undertaking field measurements of HOx and ROx.
    [Show full text]
  • Current Trends in Laser Fusion Driver and Beam Combination Laser Systems Using Stimulated Brillouin Scattering Phase Conjugate Mirrors for a Fusion Driver
    Journal of the Korean Physical Society, Vol. 56, No. 1, January 2010, pp. 177∼183 Current Trends in Laser Fusion Driver and Beam Combination Laser Systems Using Stimulated Brillouin Scattering Phase Conjugate Mirrors for a Fusion Driver Hong Jin Kong,∗ Jae Sung Shin, Du Hyun Beak and Sangwoo Park Department of Physics, KAIST, Daejeon 305-701 Jin Woo Yoon Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 500-712 (Received 11 January 2009, in final form 22 June 2009) Laser facilities in the world have been developing flash-lamp-pumped ultrahigh-energy solid-state lasers for fusion research and high-repetition diode-pumped solid-state lasers to act as commercial fusion drivers. A commercial laser fusion driver requires a high-energy beam with a total energy of several megajoules per pulse in several nanoseconds with a ∼10-Hz repetition rate. However, current laser technologies have limitations in raising the beam energy when operating with a high repetition rate, which is necessary for a commercial fusion driver to function properly. The beam combination laser system, which that uses stimulated Brillouin scattering phase conjugate mirrors, is a promising candidate for a fusion driver because it can obtain both a high energy and a high repetition rate with separate amplifications. For the realization of the beam combination laser system, a self-phase control technique was proposed for the coherent beam combined output, and its principle was demonstrated experimentally. PACS numbers: 52.58.N, 42.60, 42.65.H, 42.65.E Keywords: Laser fusion driver, High-energy laser, Beam combination, Phase conjugation, Stimulated Bril- louin scattering DOI: 10.3938/jkps.56.177 I.
    [Show full text]
  • Veres Árpád a Fúziós Atomerőmű Védőközegében Keletkező
    Sugárvédelem III. évf. (2010) 1. szám 1-11 A fúziós atomerőmű védőközegében keletkező fotonukleáris folyamatok és azok sugárvédelmi aspektusai Veres Árpád MTA Izotópkutató Intézet, H-1525 Budapest, P.O.B. 77 e-mail: [email protected] A kézirat beérkezett: 2010.01.25., közlésre elfogadva: 2010.02.22. Title – Photonuclear processes produced by shields of fusion power plants and its radiation safety aspects Abstract − A major effort is underway around the world directed to the control and application of thermonuclear processes. The primary motivation is the production of clean, cheap power in controlled thermonuclear power plants. The deuterium-tritium (DT) fusion process appears to be the most promising for this purpose. The intent of this paper is to point out that the major personnel shielding problems in the use of intense DT reactions might be associated with the primary and secondary hard γ-rays rather than with the 14.1 MeV neutrons produced in the blanket materials. In addition to the 14.1 MeV neutron produced in the DT reaction, 16.7 MeV γ-rays are also produced with a small probability. The primary problem is not the γ-rays themselves, but rather the photo neutrons which they produce. Keywords – DT fusion, thermonuclear process, laser driven fusion power plants, magnetic and inertial confinement, photo neutrons Kivonat - A világon igen nagy anyagi és szellemi er ıfeszítéssel folynak kísérletek a könny ő atommagok termonukleáris folyamatainak atomer ımői alkalmazására. Els ıdleges motiváció, a tisztább és olcsóbb energia el ıállítása szabályozott termonukleáris atomer ımővekben. Erre a célra a deutérium-trícium (DT) reakció t őnik a legmegfelel ıbbnek.
    [Show full text]
  • Laser Fusion: the First Ten Years 1962-1972
    UCRL-BOOK-222681 Laser Fusion: The First Ten Years 1962-1972 R. E. Kidder July 7, 2006 Inertial Confinement Nuclear Fusion: A Historical Approach by its Pioneers This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. Updated October 14, 2003 LASER FUSION: THE FIRST TEN YEARS 1962-1972 Ray E. Kidder Introduction This account of the beginning of the program on laser fusion at Livermore in 1962, and its subsequent development during the decade ending in 1972, was originally prepared as a contribution to the January 1991 symposium “Achievements in Physics” honoring Professor Keith Brueckner upon his retirement from the University of San Diego at La Jolla. It is a personal recollection of work at Livermore from my vantage point as its scientific leader, and of events elsewhere that I thought significant.
    [Show full text]
  • ABSTRACT Title of Dissertation
    ABSTRACT Title of Dissertation: EXPERIMENTAL CHARACTERIZATION OF ATMOSPHERIC TURBULENCE SUPPORTED BY ADVANCED PHASE SCREEN SIMULATIONS Daniel A. Paulson, Doctor of Philosophy, 2020 Dissertation directed by: Professor Christopher C. Davis Department of Electrical and Computer Engineering Characterization of optical propagation through the low turbulent atmosphere has been a topic of scientific investigation for decades, and has important engineering applications in the fields of free space optical communications, remote sensing, and directed energy. Traditional theories, starting with early radio science, have flowed down from the assumption of three dimensional statistical symmetry of so-called fully developed, isotropic turbulence. More recent experimental results have demonstrated that anisotropy and irregular frequency domain characteristics are regularly observed near boundaries of the atmosphere, and similar findings have been reported in computational fluid dynamics literature. We have used a multi-aperture transmissometer in field testing to characterize atmospheric transparency, refractive index structure functions, and turbulence anisotropy near atmospheric boundaries. Additionally, we have fielded arrays of resistive temperature detector probes alongside optical propagation paths to provide direct measurements of temperature and refractive index statistics supporting optical turbulence observations. We are backing up these experimental observations with a modified algorithm for modeling optical propagation through atmospheric turbulence. Our new phase screen approach utilizes a randomized spectral sampling algorithm to emulate the turbulence energy spectrum and improve modeling of low frequency fluctuations and improve convergence with theory. We have used the new algorithm to investigate open theoretical topics, such as the behavior of beam statistics in the strong fluctuation regime as functions of anisotropy parameters, and energy spectrum power law behavior.
    [Show full text]