1
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Law KFF, Abe Y, Morace A, Arikawa Y, Sakata S, Lee S, Matsuo K, Morita H, Ochiai Y, Liu C, Yogo A, Okamoto K, Golovin D, Ehret M, Ozaki T, Nakai M, Sentoku Y, Santos JJ, d'Humières E, Korneev P, Fujioka S. Relativistic magnetic reconnection in laser laboratory for testing an emission mechanism of hard-state black hole system. Phys Rev E 2020; 102:033202. [PMID: 33075864 DOI: 10.1103/physreve.102.033202] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 07/28/2020] [Indexed: 11/07/2022]
Abstract
Magnetic reconnection in a relativistic electron magnetization regime was observed in a laboratory plasma produced by a high-intensity, large energy, picoseconds laser pulse. Magnetic reconnection conditions realized with a laser-driven several kilotesla magnetic field is comparable to that in the accretion disk corona of black hole systems, i.e., Cygnus X-1. We observed particle energy distributions of reconnection outflow jets, which possess a power-law component in a high-energy range. The hardness of the observed spectra could explain the hard-state x-ray emission from accreting black hole systems.
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Affiliation(s)
- K F F Law
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan.,Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Y Abe
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - A Morace
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Y Arikawa
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - S Sakata
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan.,Administration and Technology Center for Science and Engineering, Technology Management Division, Waseda University, 3-4-1 Okubo, Shinjyuku-ku, Tokyo 169-8555, Japan
| | - S Lee
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - K Matsuo
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan.,Center for Energy Research, University of California, San Diego, La Jolla, California 92093-0417, USA
| | - H Morita
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Y Ochiai
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - C Liu
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - A Yogo
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan.,PRESTO, Japan Science and Technology Agency, 4-1-8 Honmachi, Kawaguchi, Saitama 332-0012, Japan
| | - K Okamoto
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - D Golovin
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - M Ehret
- Université de Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, Talence, France.,Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany
| | - T Ozaki
- National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-Cho, Toki, Gifu 509-5292, Japan
| | - M Nakai
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Y Sentoku
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - J J Santos
- Université de Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, Talence, France
| | - E d'Humières
- Université de Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, Talence, France
| | - Ph Korneev
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 31 Kashirskoe shosse, Moscow, 115409, Russian Federation.,P. N. Lebedev Physics Institute, Russian Academy of Sciences, 53 Leninskiy Prospekt, Moscow, 119991, Russian Federation
| | - S Fujioka
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
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2
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Abstract
We describe experiments and simulations of dynamical merging with two Taylor state plasmas in a Swarthmore Spheromak Experiment (SSX) device. Taylor states are formed by magnetized plasma guns at opposite ends of the device. We performed experiments with Taylor states of both senses of magnetic helicity (right-handed twist or left-handed twist). We present results of both counter-helicity merging (one side left-handed, the other right-handed) and co-helicity merging (both sides left-handed). Experiments show significant ion heating, consistent with magnetic reconnection. We suggest that the merged, warm state could be a suitable target for future magneto-inertial fusion experiments. Magnetohydrodynamic simulations of these experiments reveal the structure of the final relaxed, merged state.
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3
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The Mochi LabJet Experiment for Measurements of Canonical Helicity Injection in a Laboratory Astrophysical Jet. ACTA ACUST UNITED AC 2018. [DOI: 10.3847/1538-4365/aaba6f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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4
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Raman R, Brown T, El-Guebaly LA, Jarboe TR, Nelson BA, Menard JE. Design Description for a Coaxial Helicity Injection Plasma Start-Up System for a ST-FNSF. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst14-976] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- R. Raman
- University of Washington, AERB 352250, Seattle, WA, 98195, USA
| | - T. Brown
- Princeton Plasma Physics Laboratory, PO Box 451, Princeton, NJ, 08543, USA
| | - L. A. El-Guebaly
- University of Wisconsin, 1500 Engineering Dr., Madison, WI, 53706, USA
| | - T. R. Jarboe
- University of Washington, AERB 352250, Seattle, WA, 98195, USA
| | - B. A. Nelson
- University of Washington, AERB 352250, Seattle, WA, 98195, USA
| | - J. E. Menard
- Princeton Plasma Physics Laboratory, PO Box 451, Princeton, NJ, 08543, USA
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5
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Zweibel EG, Yamada M. Perspectives on magnetic reconnection. Proc Math Phys Eng Sci 2016; 472:20160479. [PMID: 28119547 PMCID: PMC5247523 DOI: 10.1098/rspa.2016.0479] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 10/31/2016] [Indexed: 11/12/2022] Open
Abstract
Magnetic reconnection is a topological rearrangement of magnetic field that occurs on time scales much faster than the global magnetic diffusion time. Since the field lines break on microscopic scales but energy is stored and the field is driven on macroscopic scales, reconnection is an inherently multi-scale process that often involves both magnetohydrodynamic (MHD) and kinetic phenomena. In this article, we begin with the MHD point of view and then describe the dynamics and energetics of reconnection using a two-fluid formulation. We also focus on the respective roles of global and local processes and how they are coupled. We conclude that the triggers for reconnection are mostly global, that the key energy conversion and dissipation processes are either local or global, and that the presence of a continuum of scales coupled from microscopic to macroscopic may be the most likely path to fast reconnection.
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Affiliation(s)
- Ellen G Zweibel
- Departments of Astronomy and Physics, University of Wisconsin-Madison, Madison, WI, USA; Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ, USA
| | - Masaaki Yamada
- Departments of Astronomy and Physics, University of Wisconsin-Madison, Madison, WI, USA; Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ, USA
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6
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Suttle LG, Hare JD, Lebedev SV, Swadling GF, Burdiak GC, Ciardi A, Chittenden JP, Loureiro NF, Niasse N, Suzuki-Vidal F, Wu J, Yang Q, Clayson T, Frank A, Robinson TS, Smith RA, Stuart N. Structure of a Magnetic Flux Annihilation Layer Formed by the Collision of Supersonic, Magnetized Plasma Flows. PHYSICAL REVIEW LETTERS 2016; 116:225001. [PMID: 27314720 DOI: 10.1103/physrevlett.116.225001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Indexed: 06/06/2023]
Abstract
We present experiments characterizing the detailed structure of a current layer, generated by the collision of two counterstreaming, supersonic and magnetized aluminum plasma flows. The antiparallel magnetic fields advected by the flows are found to be mutually annihilated inside the layer, giving rise to a bifurcated current structure-two narrow current sheets running along the outside surfaces of the layer. Measurements with Thomson scattering show a fast outflow of plasma along the layer and a high ion temperature (T_{i}∼Z[over ¯]T_{e}, with average ionization Z[over ¯]=7). Analysis of the spatially resolved plasma parameters indicates that the advection and subsequent annihilation of the inflowing magnetic flux determines the structure of the layer, while the ion heating could be due to the development of kinetic, current-driven instabilities.
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Affiliation(s)
- L G Suttle
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - J D Hare
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - S V Lebedev
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - G F Swadling
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - G C Burdiak
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - A Ciardi
- Sorbonne Universités, UPMC Universités Paris 6, UMR 8112, LERMA, Paris F-75005, France
- LERMA, Observatoire de Paris, PSL Research University, CNRS, UMR 8112, Paris F-75014, France
| | - J P Chittenden
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - N F Loureiro
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - N Niasse
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - F Suzuki-Vidal
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - J Wu
- State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, China
| | - Q Yang
- Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
| | - T Clayson
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - A Frank
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
| | - T S Robinson
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - R A Smith
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - N Stuart
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
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7
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Tanabe H, Yamada T, Watanabe T, Gi K, Kadowaki K, Inomoto M, Imazawa R, Gryaznevich M, Michael C, Crowley B, Conway NJ, Scannell R, Harrison J, Fitzgerald I, Meakins A, Hawkes N, McClements KG, O'Gorman T, Cheng CZ, Ono Y. Electron and Ion Heating Characteristics during Magnetic Reconnection in the MAST Spherical Tokamak. PHYSICAL REVIEW LETTERS 2015; 115:215004. [PMID: 26636857 DOI: 10.1103/physrevlett.115.215004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Indexed: 06/05/2023]
Abstract
Electron and ion heating characteristics during merging reconnection start-up on the MAST spherical tokamak have been revealed in detail using a 130 channel yttrium aluminum garnet (YAG) and a 300 channel Ruby-Thomson scattering system and a new 32 chord ion Doppler tomography diagnostic. Detailed 2D profile measurements of electron and ion temperature together with electron density have been achieved for the first time and it is found that electron temperature forms a highly localized hot spot at the X point and ion temperature globally increases downstream. For the push merging experiment when the guide field is more than 3 times the reconnecting field, a thick layer of a closed flux surface form by the reconnected field sustains the temperature profile for longer than the electron and ion energy relaxation time ~4-10 ms, both characteristic profiles finally forming a triple peak structure at the X point and downstream. An increase in the toroidal guide field results in a more peaked electron temperature profile at the X point, and also produces higher ion temperatures at this point, but the ion temperature profile in the downstream region is unaffected.
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Affiliation(s)
- H Tanabe
- Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan
| | - T Yamada
- Faculty of Arts and Science, Kyusyu University, Fukuoka 819-0395, Japan
| | - T Watanabe
- Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan
| | - K Gi
- Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan
| | - K Kadowaki
- Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan
| | - M Inomoto
- Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan
| | - R Imazawa
- Japan Atomic Energy Agency, Ibaraki 311-0193, Japan
| | - M Gryaznevich
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - C Michael
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - B Crowley
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - N J Conway
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - R Scannell
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - J Harrison
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - I Fitzgerald
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - A Meakins
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - N Hawkes
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - K G McClements
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - T O'Gorman
- CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, United Kingdom
| | - C Z Cheng
- Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan
- Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan 70101, Taiwan
| | - Y Ono
- Graduate School of Frontier Sciences, University of Tokyo, Tokyo 113-0032, Japan
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8
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Yoo J, Yamada M, Ji H, Myers CE. Observation of ion acceleration and heating during collisionless magnetic reconnection in a laboratory plasma. PHYSICAL REVIEW LETTERS 2013; 110:215007. [PMID: 23745892 DOI: 10.1103/physrevlett.110.215007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Indexed: 06/02/2023]
Abstract
The ion dynamics in a collisionless magnetic reconnection layer are studied in a laboratory plasma. The measured in-plane plasma potential profile, which is established by electrons accelerated around the electron diffusion region, shows a saddle-shaped structure that is wider and deeper towards the outflow direction. This potential structure ballistically accelerates ions near the separatrices toward the outflow direction. Ions are heated as they travel into the high-pressure downstream region.
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Affiliation(s)
- Jongsoo Yoo
- Center for Magnetic Self-organization in Laboratory and Astrophysical Plasmas, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
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9
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Ono Y, Tanabe H, Hayashi Y, Ii T, Narushima Y, Yamada T, Inomoto M, Cheng CZ. Ion and electron heating characteristics of magnetic reconnection in a two flux loop merging experiment. PHYSICAL REVIEW LETTERS 2011; 107:185001. [PMID: 22107637 DOI: 10.1103/physrevlett.107.185001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2011] [Indexed: 05/31/2023]
Abstract
Characteristics of the high-power reconnection heating were measured for the first time directly by two-dimensional measurements of ion and electron temperatures. While electrons are heated mainly inside the current sheet by the Ohmic heating power, ions are heated mainly by fast shock or viscosity damping of the reconnection outflow in the two downstream areas. The magnetic reconnection converts the energy of reconnecting magnetic field B(p) mostly to the ion thermal energy, indicating that the reconnection heating energy is proportional to B(p)(2).
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Affiliation(s)
- Y Ono
- Graduate School of Frontier Sciences, University of Tokyo, Tokyo, Japan.
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10
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Raman R, Mueller D, Nelson BA, Jarboe TR, Gerhardt S, Kugel HW, Leblanc B, Maingi R, Menard J, Ono M, Paul S, Roquemore L, Sabbagh S, Soukhanovskii V. Demonstration of Tokamak ohmic flux saving by transient coaxial helicity injection in the national spherical torus experiment. PHYSICAL REVIEW LETTERS 2010; 104:095003. [PMID: 20366991 DOI: 10.1103/physrevlett.104.095003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Indexed: 05/29/2023]
Abstract
Transient coaxial helicity injection (CHI) started discharges in the National Spherical Torus Experiment (NSTX) have attained peak currents up to 300 kA and when coupled to induction, it has produced up to 200 kA additional current over inductive-only operation. CHI in NSTX has shown to be energetically quite efficient, producing a plasma current of about 10 A/J of capacitor bank energy. In addition, for the first time, the CHI-produced toroidal current that couples to induction continues to increase with the energy supplied by the CHI power supply at otherwise similar values of the injector flux, indicating the potential for substantial current generation capability by CHI in NSTX and in future toroidal devices.
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Affiliation(s)
- R Raman
- University of Washington, Seattle, Washington, USA.
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11
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Shaikh D, Shukla PK. 3D simulations of fluctuation spectra in the hall-MHD plasma. PHYSICAL REVIEW LETTERS 2009; 102:045004. [PMID: 19257431 DOI: 10.1103/physrevlett.102.045004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Indexed: 05/27/2023]
Abstract
Turbulent spectral cascades are investigated by means of fully three-dimensional (3D) simulations of a compressible Hall-magnetohydrodynamic (H-MHD) plasma in order to understand the observed spectral break in the solar wind turbulence spectra in the regime where the characteristic length scales associated with electromagnetic fluctuations are smaller than the ion gyroradius. In this regime, the results of our 3D simulations exhibit that turbulent spectral cascades in the presence of a mean magnetic field follow an omnidirectional anisotropic inertial-range spectrum close to k(-7/3). The latter is associated with the Hall current arising from nonequal electron and ion fluid velocities in our 3D H-MHD plasma model.
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Affiliation(s)
- Dastgeer Shaikh
- Center for Space Plasma and Aeronomic Research, The University of Alabama, Huntsville, Alabama 35899, USA.
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12
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Kesich A, Bonde J, Egedal J, Fox W, Goodwin R, Katz N, Le A. Magnetic flux array for spontaneous magnetic reconnection experiments. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:063505. [PMID: 18601406 DOI: 10.1063/1.2937193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Experimental investigation of reconnection in magnetized plasmas relies on accurate characterization of the evolving magnetic fields. In experimental configurations where the plasma dynamics are reproducible, magnetic data can be collected in multiple discharges and combined to provide spatially resolved profiles of the plasma dynamics. However, in experiments on spontaneous magnetic reconnection recently undertaken at the Versatile Toroidal Facility at MIT, the reconnection process is not reproducible and all information on the plasma must be collected in a single discharge. This paper describes a newly developed magnetic flux array which directly measures the toroidal component of the magnetic vector potential, A(phi). From the measured A(phi), the magnetic field geometry, current density, and reconnection rate are readily obtained, facilitating studies of the three-dimensional dynamics of spontaneous magnetic reconnection. The novel design of the probe array allows for accurate characterization of profiles of A(phi) at multiple toroidal angles using a relatively small number of signal channels and with minimal disturbance of the plasma.
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Affiliation(s)
- A Kesich
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, MA 02139, USA
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13
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Gangadhara S, Craig D, Ennis DA, Hartog DJD, Fiksel G, Prager SC. Spatially resolved measurements of ion heating during impulsive reconnection in the Madison Symmetric Torus. PHYSICAL REVIEW LETTERS 2007; 98:075001. [PMID: 17359029 DOI: 10.1103/physrevlett.98.075001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2006] [Indexed: 05/14/2023]
Abstract
The impurity ion temperature evolution has been measured during three types of impulsive reconnection events in the Madison Symmetric Torus reversed field pinch. During an edge reconnection event, the drop in stored magnetic energy is small and ion heating is observed to be limited to the outer half of the plasma. Conversely, during a global reconnection event the drop in stored magnetic energy is large, and significant heating is observed at all radii. For both kinds of events, the drop in magnetic energy is sufficient to explain the increase in ion thermal energy. However, not all types of reconnection lead to ion heating. During a core reconnection event, both the stored magnetic energy and impurity ion temperature remain constant. The results suggest that a drop in magnetic energy is required for ions to be heated during reconnection, and that when this occurs heating is localized near the reconnection layer.
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Affiliation(s)
- S Gangadhara
- University of Wisconsin, Madison, Wisconsin and Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, Madison, Wisconsin 53706, USA
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14
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Mininni PD, Pouquet AG, Montgomery DC. Small-scale structures in three-dimensional magnetohydrodynamic turbulence. PHYSICAL REVIEW LETTERS 2006; 97:244503. [PMID: 17280293 DOI: 10.1103/physrevlett.97.244503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Indexed: 05/13/2023]
Abstract
We investigate using direct numerical simulations with grids up to 1536(3) points, the rate at which small scales develop in a decaying three-dimensional MHD flow both for deterministic and random initial conditions. Parallel current and vorticity sheets form at the same spatial locations, and further destabilize and fold or roll up after an initial exponential phase. At high Reynolds numbers, a self-similar evolution of the current and vorticity maxima is found, in which they grow as a cubic power of time; the flow then reaches a finite dissipation rate independent of the Reynolds number.
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Affiliation(s)
- P D Mininni
- National Center for Atmospheric Research, P.O. Box 3000, Boulder, Colorado 80307, USA
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15
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Recent Advances in the SPIRIT (Self-organized Plasma with Induction, Reconnection, and Injection Techniques) Concept. JOURNAL OF FUSION ENERGY 2006. [DOI: 10.1007/s10894-006-9043-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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16
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Raman R, Nelson BA, Bell MG, Jarboe TR, Mueller D, Bigelow T, Leblanc B, Maqueda R, Menard J, Ono M, Wilson R. Efficient generation of closed magnetic flux surfaces in a large spherical tokamak using coaxial helicity injection. PHYSICAL REVIEW LETTERS 2006; 97:175002. [PMID: 17155478 DOI: 10.1103/physrevlett.97.175002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Indexed: 05/12/2023]
Abstract
A method of coaxial helicity injection has successfully produced a closed flux current without the use of the central solenoid in the NSTX device, on a size scale closer to a spherical torus reactor, for a proof-of-principle demonstration of this concept. For the first time, a remarkable 60 times current multiplication factor was achieved. Grad-Shafranov plasma equilibrium reconstructions are used to verify the existence of closed flux current. In some discharges the generated current persists for a surprisingly long time approximately 400 ms.
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Affiliation(s)
- R Raman
- University of Washington, Seattle, Washington, USA
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17
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Inomoto M, Gerhardt SP, Yamada M, Ji H, Belova E, Kuritsyn A, Ren Y. Coupling between global geometry and the local hall effect leading to reconnection-layer symmetry breaking. PHYSICAL REVIEW LETTERS 2006; 97:135002. [PMID: 17026040 DOI: 10.1103/physrevlett.97.135002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Indexed: 05/12/2023]
Abstract
The coupling between the global reconnection geometry and the local microphysics, caused by the Hall effect, is studied during counterhelicity plasma merging in the magnetic reconnection experiment. The structure of the reconnection layer is significantly modified by reversing the sign of the toroidal fields, which affects the manifestation of the Hall effect in the collisionless regime. The local two-fluids physics changes the global boundary conditions, and this combination effect consequently provides different reconnection rates, magnetic field structure, and plasma flow patterns for two different counterhelicity merging cases in the collisionless regime.
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Affiliation(s)
- Michiaki Inomoto
- Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543, USA
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18
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Stark A, Fox W, Egedal J, Grulke O, Klinger T. Laser-induced fluorescence measurement of the ion-energy-distribution function in a collisionless reconnection experiment. PHYSICAL REVIEW LETTERS 2005; 95:235005. [PMID: 16384314 DOI: 10.1103/physrevlett.95.235005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2005] [Revised: 08/02/2005] [Indexed: 05/05/2023]
Abstract
Observations in space and laboratory plasmas suggest magnetic reconnection as a mechanism for ion heating and formation of non-Maxwellian ion velocity distribution functions (IVDF). Laser-induced fluorescence measurements of the IVDF parallel to the X line of a periodically driven reconnection experiment are presented. A time-resolved analysis yields the evolution of the IVDF within a reconnection cycle. It is shown that reconnection causes a strong increase of the ion temperature, where the strongest increase is found at the maximum reconnection rate. Monte Carlo simulations demonstrate that ion heating is a consequence of the in-plane electric field that forms around the X line in response to reconnection.
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Affiliation(s)
- A Stark
- Max-Planck Institute for Plasma Physics, EURATOM Association, Greifswald 17491, Germany
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19
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Guo HY, Hoffman AL, Steinhauer LC, Miller KE. Observations of improved stability and confinement in a high-beta self-organized spherical-torus-like field-reversed configuration. PHYSICAL REVIEW LETTERS 2005; 95:175001. [PMID: 16383833 DOI: 10.1103/physrevlett.95.175001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Indexed: 05/05/2023]
Abstract
An extremely high-beta (over 85%) self-organized field-reversed configuration (FRC) with a spherical-torus- (ST-)like core is produced in the translation, confinement, and sustainment experiment by highly super-Alfvénic translation of a spheromaklike plasmoid. Substantial flux conversion from toroidal into poloidal occurs during the capture process, resulting in the ST-like core. This plasma state exhibits a remarkable stabilizing property for the ubiquitous centrifugally driven interchange modes present in theta-pinch formed FRCs. This is explained, for the first time, by a simple model taking into account magnetic shear and centrifugal effects. The FRC-ST configuration has up to 4 times improvement in flux confinement times over the scaling of conventional theta-pinch formed FRCs and, thus, a significant improvement in the resistivity and transport.
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Affiliation(s)
- H Y Guo
- Redmond Plasma Physics Laboratory, University of Washington, Seattle, Washington 98195, USA
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20
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Kawamori E, Ono Y. Effect of ion skin depth on relaxation of merging spheromaks to a field-reversed configuration. PHYSICAL REVIEW LETTERS 2005; 95:085003. [PMID: 16196867 DOI: 10.1103/physrevlett.95.085003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2004] [Indexed: 05/04/2023]
Abstract
The effect of ion skin depth on the relaxation of merging spheromaks to a field-reversed configuration (FRC) is studied experimentally for a wide range of size parameter S* (ratio of minor radius to ion skin depth) from 1 to 7. The two merging spheromaks are observed to relax to an FRC or a new spheromak depending on whether the initial poloidal eigenvalue is smaller or larger than a threshold value. The bifurcation value is found to increase with decreasing size parameter S*, indicating that the low-S* condition provides a wide bifurcated range of relaxation to an FRC. The FRC-style relaxation under the low-S* conditions was accompanied by the suppression of the low-n modes (n is the toroidal mode number) activity. The fast rotations of the modes were followed by suppression of the low-n modes.
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Affiliation(s)
- Eiichirou Kawamori
- High Temperature Plasma Center, University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan
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21
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Ishizawa A, Horiuchi R. Suppression of Hall-term effects by gyroviscous cancellation in steady collisionless magnetic reconnection. PHYSICAL REVIEW LETTERS 2005; 95:045003. [PMID: 16090817 DOI: 10.1103/physrevlett.95.045003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2005] [Indexed: 05/03/2023]
Abstract
The formation of an ion-dissipation region, in which motions of electrons and ions decouple and fast magnetic reconnection occurs, is demonstrated during a steady state of two-dimensional collisionless driven reconnection by means of full-particle simulations. The Hall-term effect is suppressed due to the gyroviscous cancellation at scales between the ion-skin depth and ion-meandering-orbit scale, and thus ions are tied to the magnetic field. The ion frozen-in constraint is strongly broken by nongyrotropic pressure tensor effects due to ion-meandering motion, and thus the ion-dissipation region is formed at scales below the ion-meandering-orbit scale. A similar process is observed in the formation of an electron-dissipation region. These two dissipation regions are clearly observed in an out-of-plane current density profile.
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Affiliation(s)
- A Ishizawa
- National Institute for Fusion Science, Toki, Japan.
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22
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Woodruff S, Stallard BW, McLean HS, Hooper EB, Bulmer R, Cohen BI, Hill DN, Holcomb CT, Moller J, Wood RD. Increasing the magnetic helicity content of a plasma by pulsing a magnetized source. PHYSICAL REVIEW LETTERS 2004; 93:205002. [PMID: 15600933 DOI: 10.1103/physrevlett.93.205002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2004] [Indexed: 05/24/2023]
Abstract
By operating a magnetized coaxial gun in a pulsed mode it is possible to produce large voltage pulses of duration approximately 500 mus while reaching a few kV, giving a discrete input of helicity into a spheromak. In the sustained spheromak physics experiment (SSPX), it is observed that pulsing serves to nearly double the stored magnetic energy and double the temperature. We discuss these results by comparison with 3D MHD simulations of the same phenomenon.
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Affiliation(s)
- S Woodruff
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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23
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Ji H, Terry S, Yamada M, Kulsrud R, Kuritsyn A, Ren Y. Electromagnetic fluctuations during fast reconnection in a laboratory plasma. PHYSICAL REVIEW LETTERS 2004; 92:115001. [PMID: 15089143 DOI: 10.1103/physrevlett.92.115001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2003] [Indexed: 05/24/2023]
Abstract
Experimental evidence for a positive correlation is established between the magnitude of electromagnetic fluctuations up to the lower-hybrid frequency range and enhancement of reconnection rates in a well-controlled laboratory plasma. The fluctuations belong to the right-hand polarized whistler wave branch, propagating obliquely to the reconnecting magnetic field, with a phase velocity comparable to the relative drift velocity between electrons and ions. The measured short coherence lengths indicate their strongly nonlinear nature.
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Affiliation(s)
- Hantao Ji
- Princeton Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543, USA
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24
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Egedal J, Fasoli A, Nazemi J. Dynamical plasma response during driven magnetic reconnection. PHYSICAL REVIEW LETTERS 2003; 90:135003. [PMID: 12689297 DOI: 10.1103/physrevlett.90.135003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2002] [Revised: 11/25/2002] [Indexed: 05/24/2023]
Abstract
Direct measurements of a collisionless current channel during driven magnetic reconnection are obtained for the first time on the Versatile Toroidal Facility. The size of the diffusion region is found to scale with the electron drift orbit width, independent of the ion mass and plasma density. Based on experimental observations, analytic expressions governing the dynamical evolution of the current profile and the formation of the electrostatic potential that develops in response to the externally imposed reconnection drive are established. This time response is closely linked to the presence of ion polarization currents.
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Affiliation(s)
- J Egedal
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139, USA.
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25
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Woodruff S, Hill DN, Stallard BW, Bulmer R, Cohen B, Holcomb CT, Hooper EB, McLean HS, Moller J, Wood RD. New mode of operating a magnetized coaxial plasma gun for injecting magnetic helicity into a spheromak. PHYSICAL REVIEW LETTERS 2003; 90:095001. [PMID: 12689228 DOI: 10.1103/physrevlett.90.095001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2002] [Indexed: 05/24/2023]
Abstract
By operating a magnetized coaxial plasma gun continuously with just sufficient current to enable plasma ejection, large gun-voltage spikes (approximately 1 kV) are produced, giving the highest sustained voltage approximately 500 V and highest sustained helicity injection rate observed in the Sustained Spheromak Physics Experiment. The spheromak magnetic field increases monotonically with time, exhibiting the lowest fluctuation levels observed during formation of any spheromak (B/B>/=2%). The results suggest an important mechanism for field generation by helicity injection, namely, the merging of helicity-carrying filaments.
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Affiliation(s)
- S Woodruff
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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26
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Egedal J, Fasoli A. Single-particle dynamics in collisionless magnetic reconnection. PHYSICAL REVIEW LETTERS 2001; 86:5047-5050. [PMID: 11384417 DOI: 10.1103/physrevlett.86.5047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2000] [Indexed: 05/23/2023]
Abstract
The role of single-particle dynamics in driven magnetic reconnection in collisionless plasmas is investigated experimentally and analytically. The trapping of particle orbits in the magnetic cusp is observed to allow fast reconnection in the absence of a macroscopic current layer, at a rate identical to that of vacuum. The development of an electrostatic potential structure around the magnetic X line during reconnection is predicted theoretically and observed experimentally.
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Affiliation(s)
- J Egedal
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139, USA
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27
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Hsu SC, Fiksel G, Carter TA, Ji H, Kulsrud RM, Yamada M. Local measurement of nonclassical ion heating during magnetic reconnection. PHYSICAL REVIEW LETTERS 2000; 84:3859-3862. [PMID: 11019224 DOI: 10.1103/physrevlett.84.3859] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/1999] [Revised: 03/01/2000] [Indexed: 05/23/2023]
Abstract
Local ion temperature and flows are measured directly in the well-characterized reconnection layer of a laboratory plasma. The measurements indicate strongly that ions are heated due to reconnection and that more than half of the reconnected field energy is converted to ion thermal energy. Neither classical viscous damping of the observed sub-Alfvenic ion flows nor classical energy exchange with electrons is sufficient to account for the ion heating, suggesting the importance of nonclassical dissipation mechanisms in the reconnection layer.
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Affiliation(s)
- SC Hsu
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543, USA
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28
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Gekelman W. Review of laboratory experiments on Alfvén waves and their relationship to space observations. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/98ja00161] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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29
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Yamada M. Review of controlled laboratory experiments on physics of magnetic reconnection. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1998ja900169] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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