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Masahiro Hoshino - One of the best experts on this subject based on the ideXlab platform.
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magnetic field amplification by the weibel instability at planetary and astrophysical shocks with High Mach Number
Physical Review Letters, 2021Co-Authors: Artem Bohdan, Yosuke Matsumoto, Takanobu Amano, Masahiro Hoshino, M Pohl, J Niemiec, P Morris, A H SulaimanAbstract:Collisionless shocks are ubiquitous in the Universe and often associated with a strong magnetic field. Here, we use large-scale particle-in-cell simulations of nonrelativistic perpendicular shocks in the High-Mach-Number regime to study the amplification of the magnetic field within shocks. The magnetic field is amplified at the shock transition due to the ion-ion two-stream Weibel instability. The normalized magnetic field strength strongly correlates with the Alfv\'enic Mach Number. Mock spacecraft measurements derived from particle-in-cell simulations are fully consistent with those taken in situ at Saturn's bow shock by the Cassini spacecraft.
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electron surfing and drift accelerations in a weibel dominated High Mach Number shock
Physical Review Letters, 2017Co-Authors: Yosuke Matsumoto, Takanobu Amano, Tsunehiko N Kato, Masahiro HoshinoAbstract:How electrons get accelerated to relativistic energies in a High-Mach-Number quasiperpendicular shock is presented by means of ab initio particle-in-cell simulations in three dimensions. We found that coherent electrostatic Buneman waves and ion-Weibel magnetic turbulence coexist in a strong-shock structure whereby particles gain energy during shock surfing and subsequent stochastic drift accelerations. Energetic electrons that initially experienced the surfing acceleration undergo pitch-angle diffusion by interacting with magnetic turbulence and continuous acceleration during confinement in the shock transition region. The ion-Weibel turbulence is the key to the efficient nonthermal electron acceleration.
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electron accelerations at High Mach Number shocks two dimensional particle in cell simulations in various parameter regimes
AGU Fall Meeting Abstracts, 2012Co-Authors: Yosuke Matsumoto, Takanobu Amano, Masahiro HoshinoAbstract:Electron accelerations at High Mach Number collisionless shocks are investigated by means of two-dimensional electromagnetic particle-in-cell simulations with various Alfv´ en Mach Numbers, ion-to-electron mass ratios, and the upstream electron βe (the ratio of the thermal pressure to the magnetic pressure). We find electrons are effectively accelerated at a super-High Mach Number shock (MA ∼ 30) with a mass ratio of M/m = 100 and βe = 0.5. The electron shock surfing acceleration is an effective mechanism for accelerating the particles toward the relativistic regime even in two dimensions with a large mass ratio. Buneman instability excited at the leading edge of the foot in the super-High Mach Number shock results in a coherent electrostatic potential structure. While multi-dimensionality allows the electrons to escape from the trapping region, they can interact with the strong electrostatic field several times. Simulation runs in various parameter regimes indicate that the electron shock surfing acceleration is an effective mechanism for producing relativistic particles in extremely High Mach Number shocks in supernova remnants, provided that the upstream electron temperature is reasonably low.
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electron accelerations at High Mach Number shocks two dimensional particle in cell simulations in various parameter regimes
arXiv: High Energy Astrophysical Phenomena, 2012Co-Authors: Yosuke Matsumoto, Takanobu Amano, Masahiro HoshinoAbstract:Electron accelerations at High Mach Number collision-less shocks are investigated by means of two-dimensional electromagnetic Particle-in-Cell simulations with various Alfven Mach Numbers, ion-to-electron mass ratios, and the upstream electron beta_e (the ratio of the thermal pressure to the magnetic pressure). We found electrons are effectively accelerated at a super-High Mach Number shock (MA~30) with a mass ratio of M/m=100 and beta_e=0.5. The electron shock surfing acceleration is an effective mechanism for accelerating the particles toward the relativistic regime even in two dimensions with the large mass ratio. Buneman instability excited at the leading edge of the foot in the super-High Mach Number shock results in a coherent electrostatic potential structure. While multi-dimensionality allows the electrons to escape from the trapping region, they can interact with the strong electrostatic field several times. Simulation runs in various parameter regimes indicate that the electron shock surfing acceleration is an effective mechanism for producing relativistic particles in extremely-High Mach Number shocks in supernova remnants, provided that the upstream electron temperature is reasonably low.
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electron injection at High Mach Number quasi perpendicular shocks surfing and drift acceleration
The Astrophysical Journal, 2007Co-Authors: Takanobu Amano, Masahiro HoshinoAbstract:The process of electron injection at High Mach Number, collisionless, quasi-perpendicular shock waves is investigated by means of one-dimensional electromagnetic particle-in-cell simulations. We find that energetic electrons are generated in two steps: (1) electrons are accelerated nearly perpendicular to the local magnetic field by shock surfing acceleration at the leading edge of the shock transition region, and (2) these preaccelerated electrons are further accelerated by shock drift acceleration. As a result, energetic electrons are preferentially reflected back upstream. Shock surfing acceleration provides sufficient energy for the reflection. Therefore, it is important not only for the energization process itself, but also for triggering the secondary acceleration. We also present a theoretical model of the two-step acceleration mechanism, based on the simulation results, that can predict the injection efficiency for a subsequent diffusive shock acceleration process. We show that the injection efficiency obtained in the present model agrees well with the value obtained from Chandra X-ray observations of SN 1006. At typical supernova remnant shocks, energetic electrons injected by this mechanism can self-generate upstream Alfven waves, which scatter the energetic electrons themselves.
Takanobu Amano - One of the best experts on this subject based on the ideXlab platform.
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magnetic field amplification by the weibel instability at planetary and astrophysical shocks with High Mach Number
Physical Review Letters, 2021Co-Authors: Artem Bohdan, Yosuke Matsumoto, Takanobu Amano, Masahiro Hoshino, M Pohl, J Niemiec, P Morris, A H SulaimanAbstract:Collisionless shocks are ubiquitous in the Universe and often associated with a strong magnetic field. Here, we use large-scale particle-in-cell simulations of nonrelativistic perpendicular shocks in the High-Mach-Number regime to study the amplification of the magnetic field within shocks. The magnetic field is amplified at the shock transition due to the ion-ion two-stream Weibel instability. The normalized magnetic field strength strongly correlates with the Alfv\'enic Mach Number. Mock spacecraft measurements derived from particle-in-cell simulations are fully consistent with those taken in situ at Saturn's bow shock by the Cassini spacecraft.
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electron surfing and drift accelerations in a weibel dominated High Mach Number shock
Physical Review Letters, 2017Co-Authors: Yosuke Matsumoto, Takanobu Amano, Tsunehiko N Kato, Masahiro HoshinoAbstract:How electrons get accelerated to relativistic energies in a High-Mach-Number quasiperpendicular shock is presented by means of ab initio particle-in-cell simulations in three dimensions. We found that coherent electrostatic Buneman waves and ion-Weibel magnetic turbulence coexist in a strong-shock structure whereby particles gain energy during shock surfing and subsequent stochastic drift accelerations. Energetic electrons that initially experienced the surfing acceleration undergo pitch-angle diffusion by interacting with magnetic turbulence and continuous acceleration during confinement in the shock transition region. The ion-Weibel turbulence is the key to the efficient nonthermal electron acceleration.
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electron accelerations at High Mach Number shocks two dimensional particle in cell simulations in various parameter regimes
AGU Fall Meeting Abstracts, 2012Co-Authors: Yosuke Matsumoto, Takanobu Amano, Masahiro HoshinoAbstract:Electron accelerations at High Mach Number collisionless shocks are investigated by means of two-dimensional electromagnetic particle-in-cell simulations with various Alfv´ en Mach Numbers, ion-to-electron mass ratios, and the upstream electron βe (the ratio of the thermal pressure to the magnetic pressure). We find electrons are effectively accelerated at a super-High Mach Number shock (MA ∼ 30) with a mass ratio of M/m = 100 and βe = 0.5. The electron shock surfing acceleration is an effective mechanism for accelerating the particles toward the relativistic regime even in two dimensions with a large mass ratio. Buneman instability excited at the leading edge of the foot in the super-High Mach Number shock results in a coherent electrostatic potential structure. While multi-dimensionality allows the electrons to escape from the trapping region, they can interact with the strong electrostatic field several times. Simulation runs in various parameter regimes indicate that the electron shock surfing acceleration is an effective mechanism for producing relativistic particles in extremely High Mach Number shocks in supernova remnants, provided that the upstream electron temperature is reasonably low.
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electron accelerations at High Mach Number shocks two dimensional particle in cell simulations in various parameter regimes
arXiv: High Energy Astrophysical Phenomena, 2012Co-Authors: Yosuke Matsumoto, Takanobu Amano, Masahiro HoshinoAbstract:Electron accelerations at High Mach Number collision-less shocks are investigated by means of two-dimensional electromagnetic Particle-in-Cell simulations with various Alfven Mach Numbers, ion-to-electron mass ratios, and the upstream electron beta_e (the ratio of the thermal pressure to the magnetic pressure). We found electrons are effectively accelerated at a super-High Mach Number shock (MA~30) with a mass ratio of M/m=100 and beta_e=0.5. The electron shock surfing acceleration is an effective mechanism for accelerating the particles toward the relativistic regime even in two dimensions with the large mass ratio. Buneman instability excited at the leading edge of the foot in the super-High Mach Number shock results in a coherent electrostatic potential structure. While multi-dimensionality allows the electrons to escape from the trapping region, they can interact with the strong electrostatic field several times. Simulation runs in various parameter regimes indicate that the electron shock surfing acceleration is an effective mechanism for producing relativistic particles in extremely-High Mach Number shocks in supernova remnants, provided that the upstream electron temperature is reasonably low.
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nonlinear evolution of buneman instability and its implication for electron acceleration in High Mach Number collisionless perpendicular shocks
Physics of Plasmas, 2009Co-Authors: Takanobu AmanoAbstract:Nonlinear evolution of the Buneman instability and its application to electron acceleration in collisionless shocks are discussed. Two-dimensional particle-in-cell simulations show that the saturation level of the instability is reduced from one-dimensional simulation results. It is demonstrated that the reduced saturation level is due to the resonant wave-particle interactions with large amplitude obliquely propagating waves. A new estimate for the saturation level is given by considering the interactions with oblique modes. The effects of the large amplitude oblique modes on electron shock surfing acceleration that is mainly controlled by the Buneman instability are also investigated. Two-dimensional particle-in-cell simulations of the shock transition region are performed by adopting a local model with the periodic boundary condition. The results indicate that the presence of oblique modes introduces a stochastic behavior to the trajectories of energetic electrons. The maximum energy is limited by the ...
Tsunehiko N Kato - One of the best experts on this subject based on the ideXlab platform.
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electron surfing and drift accelerations in a weibel dominated High Mach Number shock
Physical Review Letters, 2017Co-Authors: Yosuke Matsumoto, Takanobu Amano, Tsunehiko N Kato, Masahiro HoshinoAbstract:How electrons get accelerated to relativistic energies in a High-Mach-Number quasiperpendicular shock is presented by means of ab initio particle-in-cell simulations in three dimensions. We found that coherent electrostatic Buneman waves and ion-Weibel magnetic turbulence coexist in a strong-shock structure whereby particles gain energy during shock surfing and subsequent stochastic drift accelerations. Energetic electrons that initially experienced the surfing acceleration undergo pitch-angle diffusion by interacting with magnetic turbulence and continuous acceleration during confinement in the shock transition region. The ion-Weibel turbulence is the key to the efficient nonthermal electron acceleration.
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particle acceleration and wave excitation in quasi parallel High Mach Number collisionless shocks particle in cell simulation
The Astrophysical Journal, 2015Co-Authors: Tsunehiko N KatoAbstract:We herein investigate shock formation and particle acceleration processes for both protons and electrons in a quasi-parallel High-Mach-Number collisionless shock through a long-term, large-scale, particle-in-cell simulation. We show that both protons and electrons are accelerated in the shock and that these accelerated particles generate large-amplitude Alfv?nic waves in the upstream region of the shock. After the upstream waves have grown sufficiently, the local structure of the collisionless shock becomes substantially similar to that of a quasi-perpendicular shock due to the large transverse magnetic field of the waves. A fraction of protons are accelerated in the shock with a power-law-like energy distribution. The rate of proton injection to the acceleration process is approximately constant, and in the injection process, the phase-trapping mechanism for the protons by the upstream waves can play an important role. The dominant acceleration process is a Fermi-like process through repeated shock crossings of the protons. This process is a ?fast? process in the sense that the time required for most of the accelerated protons to complete one cycle of the acceleration process is much shorter than the diffusion time. A fraction of the electrons are also accelerated by the same mechanism, and have a power-law-like energy distribution. However, the injection does not enter a steady state during the simulation, which may be related to the intermittent activity of the upstream waves. Upstream of the shock, a fraction of the electrons are pre-accelerated before reaching the shock, which may contribute to steady electron injection at a later time.
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particle acceleration and wave excitation in quasi parallel High Mach Number collisionless shocks particle in cell simulation
arXiv: High Energy Astrophysical Phenomena, 2014Co-Authors: Tsunehiko N KatoAbstract:We herein investigate shock formation and particle acceleration processes for both protons and electrons in a quasi-parallel High-Mach-Number collisionless shock through a long-term, large-scale particle-in-cell simulation. We show that both protons and electrons are accelerated in the shock and that these accelerated particles generate large-amplitude Alfv\'{e}nic waves in the upstream region of the shock. After the upstream waves have grown sufficiently, the local structure of the collisionless shock becomes substantially similar to that of a quasi-perpendicular shock due to the large transverse magnetic field of the waves. A fraction of protons are accelerated in the shock with a power-law-like energy distribution. The rate of proton injection to the acceleration process is approximately constant, and in the injection process, the phase-trapping mechanism for the protons by the upstream waves can play an important role. The dominant acceleration process is a Fermi-like process through repeated shock crossings of the protons. This process is a `fast' process in the sense that the time required for most of the accelerated protons to complete one cycle of the acceleration process is much shorter than the diffusion time. A fraction of the electrons is also accelerated by the same mechanism, and have a power-law-like energy distribution. However, the injection does not enter a steady state during the simulation, which may be related to the intermittent activity of the upstream waves. Upstream of the shock, a fraction of the electrons is pre-accelerated before reaching the shock, which may contribute to steady electron injection at a later time.
A Bhattacharjee - One of the best experts on this subject based on the ideXlab platform.
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High Mach Number laser driven magnetized collisionless shocks
Physics of Plasmas, 2017Co-Authors: D B Schaeffer, W Fox, D Haberberger, G Fiksel, A Bhattacharjee, D H Barnak, K Germaschewski, R K FollettAbstract:Collisionless shocks are ubiquitous in space and astrophysical systems, and the class of supercritical shocks is of particular importance due to their role in accelerating particles to High energies. While these shocks have been traditionally studied by spacecraft and remote sensing observations, laboratory experiments can provide reproducible and multi-dimensional datasets that provide a complementary understanding of the underlying microphysics. We present experiments undertaken on the OMEGA and OMEGA EP laser facilities that show the formation and evolution of High-Mach Number collisionless shocks created through the interaction of a laser-driven magnetic piston and a magnetized ambient plasma. Through time-resolved, 2-D imaging, we observe large density and magnetic compressions that propagate at super-Alfvenic speeds and that occur over ion kinetic length scales. The electron density and temperature of the initial ambient plasma are characterized using optical Thomson scattering. Measurements of the ...
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generation and evolution of High Mach Number laser driven magnetized collisionless shocks in the laboratory
Physical Review Letters, 2017Co-Authors: D B Schaeffer, W Fox, D Haberberger, G Fiksel, A Bhattacharjee, D H Barnak, K GermaschewskiAbstract:We present the first laboratory generation of High-Mach-Number magnetized collisionless shocks created through the interaction of an expanding laser-driven plasma with a magnetized ambient plasma. Time-resolved, two-dimensional imaging of plasma density and magnetic fields shows the formation and evolution of a supercritical shock propagating at magnetosonic Mach Number M_{ms}≈12. Particle-in-cell simulations constrained by experimental data further detail the shock formation and separate dynamics of the multi-ion-species ambient plasma. The results show that the shocks form on time scales as fast as one gyroperiod, aided by the efficient coupling of energy, and the generation of a magnetic barrier between the piston and ambient ions. The development of this experimental platform complements present remote sensing and spacecraft observations, and opens the way for controlled laboratory investigations of High-Mach Number collisionless shocks, including the mechanisms and efficiency of particle acceleration.
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generation and evolution of High Mach Number laser driven magnetized collisionless shocks in the laboratory
Physical Review Letters, 2017Co-Authors: D B Schaeffer, W Fox, D Haberberger, G Fiksel, A Bhattacharjee, D H Barnak, K GermaschewskiAbstract:We present the first laboratory generation of High-Mach-Number magnetized collisionless shocks created through the interaction of an expanding laser-driven plasma with a magnetized ambient plasma. Time-resolved, two-dimensional imaging of plasma density and magnetic fields shows the formation and evolution of a supercritical shock propagating at magnetosonic Mach Number ${M}_{\mathrm{ms}}\ensuremath{\approx}12$. Particle-in-cell simulations constrained by experimental data further detail the shock formation and separate dynamics of the multi-ion-species ambient plasma. The results show that the shocks form on time scales as fast as one gyroperiod, aided by the efficient coupling of energy, and the generation of a magnetic barrier between the piston and ambient ions. The development of this experimental platform complements present remote sensing and spacecraft observations, and opens the way for controlled laboratory investigations of High-Mach Number collisionless shocks, including the mechanisms and efficiency of particle acceleration.
N Shimada - One of the best experts on this subject based on the ideXlab platform.
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nonthermal electrons at High Mach Number shocks electron shock surfing acceleration
The Astrophysical Journal, 2002Co-Authors: Masahiro Hoshino, N ShimadaAbstract:We study the suprathermal electron acceleration mechanism in a perpendicular magnetosonic shock wave in a High Mach Number regime by using a particle-in-cell simulation. We find that shock surfing/surfatron acceleration producing suprathermal electrons occurs in the shock transition region, where a series of large-amplitude electrostatic solitary waves (ESWs) are excited by Buneman instability under the interaction between the reflected ions and the incoming electrons. It is shown that the electrons are likely to be trapped by ESWs, and during the trapping phase they can be effectively accelerated by the shock motional/convection electric field. We discuss that suprathermal electrons can be accelerated up to mic2(v0/c), where mic2 is the ion rest mass energy and v0 is the shock upstream flow velocity. Furthermore, some of these suprathermal electrons may be effectively trapped for an infinitely long time when the Alfven Mach Number MA exceeds several tens, and they are accelerated up to the shock potential energy determined by the global shock size.
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nonthermal electrons at High Mach Number shocks electron shock surfing acceleration
arXiv: Astrophysics, 2002Co-Authors: Masahiro Hoshino, N ShimadaAbstract:We study the suprathermal electron acceleration mechanism in a perpendicular magnetosonic shock wave in a High Mach Number regime by using a particle-in-cell simulation. We find that shock surfing/surftron acceleration producing the suprathermal electrons occurs in the shock transition region where a series of large amplitude electrostatic solitary waves (ESWs) are excited by Buneman instability under the interaction between the reflected ions and the incoming electrons. It is shown that the electrons are likely to be trapped by ESWs, and during the trapping phase they can be effectively accelerated by the shock motional/convection electric field. We discuss that suprathermal electrons can be accelerated up to $m_i c^2 (v_0/c)$, where $m_i c^2$ is the ion rest mass energy and $v_0$ is the shock upstream flow velocity. Furthermore, some of these suprathermal electrons may be effectively trapped for infinitely long time when Alfv\'en Mach Number $M_A$ exceeds several 10, and they are accelerated up to the shock potential energy determined by the global shock size.
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strong electron acceleration at High Mach Number shock waves simulation study of electron dynamics
The Astrophysical Journal, 2000Co-Authors: N Shimada, Masahiro HoshinoAbstract:Electron-ion dynamics in a perpendicular magnetosonic shock wave in a High Mach Number regime is studied by using the particle-in-cell simulation. It is shown that in the shock transition layer nonlinear evolution of two-stream instabilities plays an important role on the electron rapid heating and acceleration. As the shock Mach Number greatly exceeds the critical Mach Number, a series of large-amplitude, coherent electrostatic waves with the electron holes in phase space are excited by the two-stream instability between the reflected ions and the incident electrons in the shock transition layer. As the incident electrons are decelerated by the instability, other electrostatic waves grow in time by another two-stream instability between the incident ions and the decelerated incident electrons. The dynamic timescale of these instabilities is of the order of ω, where ωpe is the plasma frequency. The nonlinear interaction of these waves leads to the strong electron heating as well as the nonthermal High-energy electron acceleration in the shock transition layer.