1
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Zhang C, Hua J, Wu Y, Fang Y, Ma Y, Zhang T, Liu S, Peng B, He Y, Huang CK, Marsh KA, Mori WB, Lu W, Joshi C. Measurements of the Growth and Saturation of Electron Weibel Instability in Optical-Field Ionized Plasmas. PHYSICAL REVIEW LETTERS 2020; 125:255001. [PMID: 33416364 DOI: 10.1103/physrevlett.125.255001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 11/05/2020] [Accepted: 11/16/2020] [Indexed: 06/12/2023]
Abstract
The temporal evolution of the magnetic field associated with electron thermal Weibel instability in optical-field ionized plasmas is measured using ultrashort (1.8 ps), relativistic (45 MeV) electron bunches from a linear accelerator. The self-generated magnetic fields are found to self-organize into a quasistatic structure consistent with a helicoid topology within a few picoseconds and such a structure lasts for tens of picoseconds in underdense plasmas. The measured growth rate agrees well with that predicted by the kinetic theory of plasmas taking into account collisions. Magnetic trapping is identified as the dominant saturation mechanism.
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Affiliation(s)
- Chaojie Zhang
- Department of Electrical Engineering, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Jianfei Hua
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - Yipeng Wu
- Department of Electrical Engineering, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Yu Fang
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - Yue Ma
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - Tianliang Zhang
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - Shuang Liu
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - Bo Peng
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - Yunxiao He
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - Chen-Kang Huang
- Department of Electrical Engineering, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Ken A Marsh
- Department of Electrical Engineering, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Warren B Mori
- Department of Electrical Engineering, University of California Los Angeles, Los Angeles, California 90095, USA
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA
| | - Wei Lu
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - Chan Joshi
- Department of Electrical Engineering, University of California Los Angeles, Los Angeles, California 90095, USA
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2
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Keenan BD, Ford AL, Medvedev MV. Quasicollisional magneto-optic effects in collisionless plasmas with sub-Larmor-scale electromagnetic fluctuations. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:053102. [PMID: 26651797 DOI: 10.1103/physreve.92.053102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Indexed: 06/05/2023]
Abstract
High-amplitude, chaotic or turbulent electromagnetic fluctuations are ubiquitous in high-energy-density laboratory and astrophysical plasmas, where they can be excited by various kinetic-streaming and/or anisotropy-driven instabilities, such as the Weibel instability. These fields typically exist on "sub-Larmor scales"-scales smaller than the electron Larmor radius. Electrons moving through such magnetic fields undergo small-angle stochastic deflections of their pitch angles, thus establishing diffusive transport on long time scales. We show that this behavior, under certain conditions, is equivalent to Coulomb collisions in collisional plasmas. The magnetic pitch-angle diffusion coefficient, which acts as an effective "collision" frequency, may be substantial in these, otherwise, collisionless environments. We show that this effect, colloquially referred to as the plasma "quasicollisionality," may radically alter the expected radiative transport properties of candidate plasmas. We argue that the modified magneto-optic effects in these plasmas provide an attractive, radiative diagnostic tool for the exploration and characterization of small-scale magnetic turbulence, as well as affect inertial confinement fusion and other laser-plasma experiments.
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Affiliation(s)
- Brett D Keenan
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA
| | - Alexander L Ford
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA
| | - Mikhail V Medvedev
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA
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3
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Keenan BD, Ford AL, Medvedev MV. Transport of and radiation production by transrelativistic and nonrelativistic particles moving through sub-Larmor-scale electromagnetic turbulence. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:033104. [PMID: 26465572 DOI: 10.1103/physreve.92.033104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Indexed: 06/05/2023]
Abstract
Plasmas with electromagnetic fields turbulent at sub-Larmor scales are a feature of a wide variety of high-energy-density environments and are essential to the description of many astrophysical and laboratory plasma phenomena. Radiation from particles, whether they are relativistic or nonrelativistic, moving through small-scale magnetic turbulence has spectral characteristics distinct from both synchrotron and cyclotron radiation. The radiation, carrying information on the statistical properties of the magnetic turbulence, is also intimately related to the particle diffusive transport. We have investigated, both theoretically and numerically, the transport of nonrelativistic and trans-relativistic particles in plasmas with high-amplitude isotropic sub-Larmor-scale magnetic turbulence, and its relation to the spectra of radiation simultaneously produced by these particles. Consequently, the diffusive and radiative properties of plasmas turbulent on sub-Larmor scales may serve as a powerful tool to diagnosis laboratory and astrophysical plasmas.
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Affiliation(s)
- Brett D Keenan
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA
| | - Alexander L Ford
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA
| | - Mikhail V Medvedev
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA
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4
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Vaisseau X, Debayle A, Honrubia JJ, Hulin S, Morace A, Nicolaï P, Sawada H, Vauzour B, Batani D, Beg FN, Davies JR, Fedosejevs R, Gray RJ, Kemp GE, Kerr S, Li K, Link A, McKenna P, McLean HS, Mo M, Patel PK, Park J, Peebles J, Rhee YJ, Sorokovikova A, Tikhonchuk VT, Volpe L, Wei M, Santos JJ. Enhanced relativistic-electron-beam energy loss in warm dense aluminum. PHYSICAL REVIEW LETTERS 2015; 114:095004. [PMID: 25793822 DOI: 10.1103/physrevlett.114.095004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Indexed: 06/04/2023]
Abstract
Energy loss in the transport of a beam of relativistic electrons in warm dense aluminum is measured in the regime of ultrahigh electron beam current density over 2×10^{11} A/cm^{2} (time averaged). The samples are heated by shock compression. Comparing to undriven cold solid targets, the roles of the different initial resistivity and of the transient resistivity (upon target heating during electron transport) are directly observable in the experimental data, and are reproduced by a comprehensive set of simulations describing the hydrodynamics of the shock compression and electron beam generation and transport. We measured a 19% increase in electron resistive energy loss in warm dense compared to cold solid samples of identical areal mass.
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Affiliation(s)
- X Vaisseau
- Univ. Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence, France
| | - A Debayle
- ETSI Aeronáuticos, Universidad Politécnica de Madrid, Madrid, Spain
- CEA, DAM, DIF, F-91297 Arpajon, France
- LRC MESO, Ecole Normale Supérieure de Cachan - CMLA, 94235 Cachan, France
| | - J J Honrubia
- ETSI Aeronáuticos, Universidad Politécnica de Madrid, Madrid, Spain
| | - S Hulin
- Univ. Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence, France
| | - A Morace
- University of California, San Diego, La Jolla, California 92093, USA
| | - Ph Nicolaï
- Univ. Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence, France
| | - H Sawada
- University of California, San Diego, La Jolla, California 92093, USA
| | - B Vauzour
- Univ. Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence, France
| | - D Batani
- Univ. Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence, France
| | - F N Beg
- University of California, San Diego, La Jolla, California 92093, USA
| | - J R Davies
- Fusion Science Center for Extreme States of Matter, Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
| | - R Fedosejevs
- Department of Electrical Engineering, University of Alberta, Edmonton T6G 2G7, Canada
| | - R J Gray
- SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG, United Kingdom
| | - G E Kemp
- Physics Department, The Ohio State University, Columbus, Ohio 43210, USA
| | - S Kerr
- Department of Electrical Engineering, University of Alberta, Edmonton T6G 2G7, Canada
| | - K Li
- GoLP, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, 1049-001 Lisboa, Portugal
| | - A Link
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - P McKenna
- SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG, United Kingdom
| | - H S McLean
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M Mo
- Department of Electrical Engineering, University of Alberta, Edmonton T6G 2G7, Canada
| | - P K Patel
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - J Park
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - J Peebles
- University of California, San Diego, La Jolla, California 92093, USA
| | - Y J Rhee
- Korea Atomic Energy Research Institute (KAERI), Daejon 305-600, South Korea
| | - A Sorokovikova
- University of California, San Diego, La Jolla, California 92093, USA
| | - V T Tikhonchuk
- Univ. Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence, France
| | - L Volpe
- Univ. Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence, France
| | - M Wei
- General Atomics, San Diego, California 92121, USA
| | - J J Santos
- Univ. Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence, France
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5
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Sherlock M, Hill EG, Evans RG, Rose SJ, Rozmus W. In-depth plasma-wave heating of dense plasma irradiated by short laser pulses. PHYSICAL REVIEW LETTERS 2014; 113:255001. [PMID: 25554889 DOI: 10.1103/physrevlett.113.255001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Indexed: 06/04/2023]
Abstract
We investigate the mechanism by which relativistic electron bunches created at the surface of a target irradiated by a very short and intense laser pulse transfer energy to the deeper parts of the target. In existing theories, the dominant heating mechanism is that of resistive heating by the neutralizing return current. In addition to this, we find that large amplitude plasma waves are induced in the plasma in the wake of relativistic electron bunches. The subsequent collisional damping of these waves represents a source of heating that can exceed the resistive heating rate. As a result, solid targets heat significantly faster than has been previously considered. A new hybrid model, capable of reproducing these results, is described.
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Affiliation(s)
- M Sherlock
- Blackett Laboratory, Imperial College London, London SW7 2BZ, United Kingdom
| | - E G Hill
- Blackett Laboratory, Imperial College London, London SW7 2BZ, United Kingdom
| | - R G Evans
- Blackett Laboratory, Imperial College London, London SW7 2BZ, United Kingdom
| | - S J Rose
- Blackett Laboratory, Imperial College London, London SW7 2BZ, United Kingdom
| | - W Rozmus
- Department of Physics, University of Alberta, Edmonton, Canada T6G 2G7
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6
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Keenan BD, Medvedev MV. Particle transport and radiation production in sub-Larmor-scale electromagnetic turbulence. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:013103. [PMID: 23944564 DOI: 10.1103/physreve.88.013103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Indexed: 06/02/2023]
Abstract
The relation of particle transport of relativistic particles in plasmas with high-amplitude isotropic sub-Larmor-scale magnetic turbulence to the spectra of radiation simultaneously produced by these particles is investigated both analytically and numerically. We have found that in the asymptotic regime of very small particle deflections, the pitch-angle diffusion coefficient is directly related to the spectrum of the emitted radiation. Moreover, this spectrum provides much information about the statistical properties of the underlying magnetic turbulence. The transition from small- to large-scale jitter to synchrotron radiation regimes as a function of turbulence properties has also been explored. These results can readily be used to diagnose laboratory and astrophysical plasmas.
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Affiliation(s)
- Brett D Keenan
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA.
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7
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Kemp AJ, Divol L. Interaction physics of multipicosecond Petawatt laser pulses with overdense plasma. PHYSICAL REVIEW LETTERS 2012; 109:195005. [PMID: 23215393 DOI: 10.1103/physrevlett.109.195005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Indexed: 06/01/2023]
Abstract
We study the interaction of intense petawatt laser pulses with overdense plasma over several picoseconds, using two- and three-dimensional kinetic particle simulations. Sustained irradiation with non-diffraction-limited pulses at relativistic intensities yields conditions that differ qualitatively from what is experimentally available today. Nonlinear saturation of laser-driven density perturbations at the target surface causes recurrent emissions of plasma, which stabilize the surface and keep absorption continuously high. This dynamics leads to the acceleration of three distinct groups of electrons up to energies many times the laser ponderomotive potential. We discuss their energy distribution for applications like the fast-ignition approach to inertial confinement fusion.
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Affiliation(s)
- A J Kemp
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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8
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Nersisyan HB, Deutsch C. Instabilities for a relativistic electron beam interacting with a laser-irradiated plasma. Phys Rev E 2012; 85:056414. [PMID: 23004886 DOI: 10.1103/physreve.85.056414] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Indexed: 11/07/2022]
Abstract
The effects of a radiation field (RF) on the unstable modes developed in a relativistic electron beam-plasma interaction are investigated assuming that ω(0) > ω(p), where ω(0) is the frequency of the RF and ω(p) is the plasma frequency. These unstable modes are parametrically coupled to each other due to the RF and are a mix between two-stream and parametric instabilities. The dispersion equations are derived by the linearization of the kinetic equations for a beam-plasma system as well as the Maxwell equations. In order to highlight the effect of the radiation field we present a comparison of our analytical and numerical results obtained for nonzero RF with those for vanishing RF. Assuming that the drift velocity u(b) of the beam is parallel to the wave vector k of the excitations two particular transversal and parallel configurations of the polarization vector E(0) of the RF with respect to k are considered in detail. It is shown that in both geometries resonant and nonresonant couplings between different modes are possible. The largest growth rates are expected at the transversal configuration when E(0) is perpendicular to k. In this case it is demonstrated that, in general, the spectrum of the unstable modes in the ω-k plane is split into two distinct domains with long and short wavelengths, where the unstable modes are mainly sensitive to the beam or the RF parameters, respectively. In the parallel configuration, E(0)∥k, and at short wavelengths the growth rates of the unstable modes are sensitive to both beam and RF parameters remaining insensitive to the RF at long wavelengths.
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9
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Chatterjee G, Singh PK, Ahmed S, Robinson APL, Lad AD, Mondal S, Narayanan V, Srivastava I, Koratkar N, Pasley J, Sood AK, Kumar GR. Macroscopic transport of mega-ampere electron currents in aligned carbon-nanotube arrays. PHYSICAL REVIEW LETTERS 2012; 108:235005. [PMID: 23003966 DOI: 10.1103/physrevlett.108.235005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Indexed: 06/01/2023]
Abstract
We demonstrate that aligned carbon-nanotube arrays are efficient transporters of laser-generated mega-ampere electron currents over distances as large as a millimeter. A direct polarimetric measurement of the temporal and the spatial evolution of the megagauss magnetic fields (as high as 120 MG) at the target rear at an intensity of (10(18)-10(19)) W/cm2 was corroborated by the rear-side hot electron spectra. Simulations show that such high magnetic flux densities can only be generated by a very well collimated fast electron bunch.
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Affiliation(s)
- Gourab Chatterjee
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai, 400005, India
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10
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Cai HB, Zhu SP, Chen M, Wu SZ, He XT, Mima K. Magnetic-field generation and electron-collimation analysis for propagating fast electron beams in overdense plasmas. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:036408. [PMID: 21517605 DOI: 10.1103/physreve.83.036408] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 01/25/2011] [Indexed: 05/30/2023]
Abstract
An analytical fluid model is proposed for artificially collimating fast electron beams produced in the interaction of ultraintense laser pulses with specially engineered low-density-core-high-density-cladding structure targets. Since this theory clearly predicts the characteristics of the spontaneously generated magnetic field and its dependence on the plasma parameters of the targets transporting fast electrons, it is of substantial relevance to the target design for fast ignition. The theory also reveals that the rapid changing of the flow velocity of the background electrons in a transverse direction (perpendicular to the flow velocity) caused by the density jump dominates the generation of a spontaneous interface magnetic field for these kinds of targets. It is found that the spontaneously generated magnetic field reaches as high as 100 MG, which is large enough to collimate fast electron transport in overdense plasmas. This theory is also supported by numerical simulations performed using a two-dimensional particle-in-cell code. It is found that the simulation results agree well with the theoretical analysis.
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Affiliation(s)
- Hong-Bo Cai
- Institute of Applied Physics and Computational Mathematics, Beijing 100094, People's Republic of China.
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11
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Cai HB, Mima K, Zhou WM, Jozaki T, Nagatomo H, Sunahara A, Mason RJ. Enhancing the number of high-energy electrons deposited to a compressed pellet via double cones in fast ignition. PHYSICAL REVIEW LETTERS 2009; 102:245001. [PMID: 19659015 DOI: 10.1103/physrevlett.102.245001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Indexed: 05/28/2023]
Abstract
Particle-in-cell simulations aimed at improving the coupling efficiency of input laser energy deposited to a compressed core by using a double cone are described. It is found that the number of high-energy electrons escaping from the sides of the cone is greatly reduced by the vacuum gap inside the wing of the double cone. Two main mechanisms to confine high-energy electrons are found. These mechanisms are the sheath electric field at the rear of the inner cone wing and the quasistatic magnetic field inside the vacuum gap. The generation mechanism for the quasistatic magnetic fields is discussed in detail. It is found that the quasistatic fields continue to confine the high-energy electrons for longer than a few picoseconds. The double cones provide confinement and focusing of about 15% of the input energy for deposition in the compressed core.
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Affiliation(s)
- Hong-bo Cai
- Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
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12
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Hao B, Sheng ZM, Ren C, Zhang J. Relativistic collisional current-filamentation instability and two-stream instability in dense plasma. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 79:046409. [PMID: 19518361 DOI: 10.1103/physreve.79.046409] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Indexed: 05/27/2023]
Abstract
The collisional effects on the current-filamentation instability (CFI) and the two-stream instability (TSI), which appear as a relativistic intense electron beam penetrating into a cold dense plasma, are investigated. It is shown that the growth rate of the CFI mode is first attenuated and then enhanced by the collisional effects as the density ratio of the background plasma to the beam increases. Meanwhile, the maximum CFI growth rate is shifted to the long-wavelength region due to both the bulk plasma density increase and the collisional effects, resulting in larger filaments formation. On the other hand, collisional effects mainly attenuate the TSI and finally stabilize it. Numerical solutions under parameters close to the fast ignition scenario (FIS) are given, which show that the CFI growth rate can be enhanced by 2 orders of magnitude instead of being suppressed in the dense region. Therefore, the CFI-induced electron filaments formation and the resultant kinetic anomalous heating are potentially significant for the target heating in the FIS.
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Affiliation(s)
- Biao Hao
- Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100190, China
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13
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Green JS, Ovchinnikov VM, Evans RG, Akli KU, Azechi H, Beg FN, Bellei C, Freeman RR, Habara H, Heathcote R, Key MH, King JA, Lancaster KL, Lopes NC, Ma T, MacKinnon AJ, Markey K, McPhee A, Najmudin Z, Nilson P, Onofrei R, Stephens R, Takeda K, Tanaka KA, Theobald W, Tanimoto T, Waugh J, Van Woerkom L, Woolsey NC, Zepf M, Davies JR, Norreys PA. Effect of laser intensity on fast-electron-beam divergence in solid-density plasmas. PHYSICAL REVIEW LETTERS 2008; 100:015003. [PMID: 18232779 DOI: 10.1103/physrevlett.100.015003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Indexed: 05/25/2023]
Abstract
Metal foil targets were irradiated with 1 mum wavelength (lambda) laser pulses of 5 ps duration and focused intensities (I) of up to 4x10;{19} W cm;{-2}, giving values of both Ilambda;{2} and pulse duration comparable to those required for fast ignition inertial fusion. The divergence of the electrons accelerated into the target was determined from spatially resolved measurements of x-ray K_{alpha} emission and from transverse probing of the plasma formed on the back of the foils. Comparison of the divergence with other published data shows that it increases with Ilambda;{2} and is independent of pulse duration. Two-dimensional particle-in-cell simulations reproduce these results, indicating that it is a fundamental property of the laser-plasma interaction.
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Affiliation(s)
- J S Green
- Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX, United Kingdom
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14
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Adam JC, Héron A, Laval G. Dispersion and transport of energetic particles due to the interaction of intense laser pulses with overdense plasmas. PHYSICAL REVIEW LETTERS 2006; 97:205006. [PMID: 17155691 DOI: 10.1103/physrevlett.97.205006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Indexed: 05/12/2023]
Abstract
We study the angular distribution of relativistic electrons generated through laser-plasma interaction with pulse intensity varying from 10(18) W/cm2 up to 10(21) W/cm2 and plasma density ranging from 10 times up to 160 times critical density with the help of 2D and 3D particle-in-cell simulations. This study gives clear evidence that the divergence of the beam is an intrinsic property of the interaction of a laser pulse with a sharp density gradient. It is entirely due to the excitation of large static magnetic fields in the layer of interaction. The energy deposited in this layer increases drastically the temperature of the plasma independently of the initial temperature. This makes the plasma locally collisionless and the simulation relevant for the current experiments.
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Affiliation(s)
- J C Adam
- Centre de physique Théorique, UMR7644, Ecole Polytechnique, 91128 Palaiseau, France
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15
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Tzoufras M, Ren C, Tsung FS, Tonge JW, Mori WB, Fiore M, Fonseca RA, Silva LO. Space-charge effects in the current-filamentation or Weibel instability. PHYSICAL REVIEW LETTERS 2006; 96:105002. [PMID: 16605742 DOI: 10.1103/physrevlett.96.105002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Indexed: 05/08/2023]
Abstract
We consider how an unmagnetized plasma responds to an incoming flux of energetic electrons. We assume a return current is present and allow for the incoming electrons to have a different transverse temperature than the return current. To analyze this configuration we present a nonrelativistic theory of the current-filamentation or Weibel instability for rigorously current-neutral and nonseparable distribution functions, f(0)(p(x), p(y), p(z)) is not equal to f(x)(p(x))f(y)(p(y))f(z)(p(z)). We find that such distribution functions lead to lower growth rates because of space-charge forces that arise when the forward-going electrons pinch to a lesser degree than the colder, backward-flowing electrons. We verify the growth rate, range of unstable wave numbers, and the formation of the density filaments using particle-in-cell simulations.
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Affiliation(s)
- M Tzoufras
- Department of Electrical Engineering, University of California, Los Angeles, 90095, USA
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16
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Califano F, Del Sarto D, Pegoraro F. Three-dimensional magnetic structures generated by the development of the filamentation (Weibel) instability in the relativistic regime. PHYSICAL REVIEW LETTERS 2006; 96:105008. [PMID: 16605748 DOI: 10.1103/physrevlett.96.105008] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Indexed: 05/08/2023]
Abstract
We present three-dimensional, fully relativistic, fluid simulations of the dynamics of inhomogeneous counter streaming beams with the aim of understanding the magnetic structures that can be expected to form as a consequence of the development of the so-called Weibel instability. Ringlike structures in the transverse direction are generated as a consequence of the development of a spatially resonant mode. We describe the structures generated by beams of equal initial density and velocity and by a fast, less dense beam compensated by a slower, denser beam. We consider these two cases as schematic models of a laser produced beam propagating in a plasma with nearly equal density and in a plasma much denser than the injected beam.
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Affiliation(s)
- F Califano
- Physics Department and CNISM, University of Pisa, Pisa, Italy
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Li CK, Petrasso RD. Stopping, straggling, and blooming of directed energetic electrons in hydrogenic and arbitrary-Z plasmas. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:016402. [PMID: 16486283 DOI: 10.1103/physreve.73.016402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Indexed: 05/06/2023]
Abstract
From fundamental principles, the interaction of directed energetic electrons with hydrogenic and arbitrary-Z plasmas is analytically modeled. The effects of stopping, straggling, and beam blooming, a consequence of scattering and energy loss, are rigorously treated from a unified approach. Enhanced energy deposition occurs in the latter portion of the penetration and is inextricably linked to straggling and blooming. These effects, which have a strong Z dependence, will be important in evaluating the requirements of fast ignition and tolerable levels of electron preheat.
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Affiliation(s)
- C K Li
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Mason RJ, Dodd ES, Albright BJ. Hot-electron surface retention in intense short-pulse laser-matter interactions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:015401. [PMID: 16090028 DOI: 10.1103/physreve.72.015401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2004] [Indexed: 05/03/2023]
Abstract
Implicit hybrid plasma simulations predict that a significant fraction of the energy deposited into hot electrons can be retained near the surface of targets with steep density gradients illuminated by intense short-pulse lasers. This retention derives from the lateral transport of heated electrons randomly emitted in the presence of spontaneous magnetic fields arising near the laser spot, from geometric effects associated with a small hot-electron source, and from E fields arising in reaction to the ponderomotive force. Below the laser spot hot electrons are axially focused into a target by the B fields, and can filament in moderate Z targets by resistive Weibel-like instability, if the effective background electron temperature remains sufficiently low. Carefully engineered use of such retention in conjunction with ponderomotive density profile steepening could result in a reduced hot-electron range that aids fast ignition. Alternatively, such retention may disturb a deeper deposition needed for efficient radiography and backside fast ion generation.
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Affiliation(s)
- R J Mason
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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