Hybrid simulation of shock formation for super-Alfvénic expansion of laser ablated debris through an ambient, magnetized plasma

Clark, S. E.; Winske, D.; Schaeffer, D. B.; Everson, E. T.; Bondarenko, A. S.; Constantin, Carmen; Niemann, C.

doi:10.1063/1.4819251

Cited by 31 publications

(46 citation statements)

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“…One of its most significant findings was the unanticipated displacement of the barium ion 'comet head' (and an oppositely directed deflection of the streaming hydrogen ions) transverse to both the solar wind flow and the interplanetary magnetic field, defying the conventional expectation that the barium ions would simply move downwind 4 . While subsequent theoretical and computational e orts [5][6][7] to understand the cause of the transverse motion reached di ering conclusions, several authors 5 attributed the observations to Larmor coupling 8,9 , a collisionless momentum exchange mechanism believed to occur in various astrophysical and space-plasma environments 10,11 and to participate in cosmic magnetized collisionless shock formation [12][13][14] . Here we present the detection of Larmor coupling in a reproducible laboratory experiment that combines an explosive laser-produced plasma cloud with preformed, magnetized ambient plasma in a parameter regime relevant to the AMPTE barium releases.…”

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“…This interaction, termed Larmor coupling, thus allows the moving debris cloud to pick up the swept-over ambient ions. Larmor coupling has received extensive theoretical and numerical investigation over the past few decades, both as a basic plasma process 8,9 and as a key mechanism in the evolution of various astrophysical and space phenomena, including man-made ionospheric explosions 11 , the AMPTE artificial comets 5 , and the formation of cosmic magnetized collisionless shocks [12][13][14] . However, this process has never before been observed in a laboratory setting.…”

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Collisionless momentum transfer in space and astrophysical explosions

et al. 2017

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The AMPTE (Active Magnetospheric Particle Tracer Explorers) mission provided in situ measurements of collisionless momentum and energy exchange between an artificial, photo-ionized barium plasma cloud and the streaming, magnetized hydrogen plasma of the solar wind [1][2][3] . One of its most significant findings was the unanticipated displacement of the barium ion 'comet head' (and an oppositely directed deflection of the streaming hydrogen ions) transverse to both the solar wind flow and the interplanetary magnetic field, defying the conventional expectation that the barium ions would simply move downwind , a collisionless momentum exchange mechanism believed to occur in various astrophysical and space-plasma environments 10,11 and to participate in cosmic magnetized collisionless shock formation [12][13][14] . Here we present the detection of Larmor coupling in a reproducible laboratory experiment that combines an explosive laser-produced plasma cloud with preformed, magnetized ambient plasma in a parameter regime relevant to the AMPTE barium releases. In our experiment, time-resolved Doppler spectroscopy reveals ambient ion acceleration transverse to both the laser-produced plasma flow and the background magnetic field. Utilizing a detailed numerical simulation, we demonstrate that the ambient ion velocity distribution corresponding to the measured Doppler-shifted spectrum is qualitatively and quantitatively consistent with Larmor coupling.The AMPTE barium release experiments aimed to better understand a ubiquitous category of astrophysical and space phenomena characterized by the rapid expansion or relative motion of a dense 'debris' plasma cloud through relatively tenuous, magnetized, ambient plasma. Examples include the expansion of stellar material through the surrounding interstellar medium in supernova remnants 10 , the formation of cometary plasma tails due to the solar wind 15 , the interaction of interplanetary coronal mass ejections with the Earth's magnetosphere 16 , and man-made ionospheric explosions 17 . In these rarified environments, the Coulomb collisional mean free paths exceed the observed interaction length scales by many orders of magnitude, signifying that the debris plasma exchanges momentum and energy with the ambient plasma via collisionless, collective, electromagnetic effects. In addition, the relative motion of the debris cloud produces electric polarization fields between the magnetically confined electrons and the relatively freestreaming ions, resulting in E × B drift electron currents that expel the magnetic field within the cloud volume (the diamagnetic cavity) and enhance it at the cloud edge (the magnetic compression) 18 . The general evolution in the reference frame of the magnetized ambient plasma is thus a deceleration of the debris cloud as it couples to the ambient plasma via collisionless processes and deforms the magnetic field.We here consider explosive astrophysical and space environments characterized by a perpendicular-to-B debris plasma flow speed V d that exceed...

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Collisionless momentum transfer in space and astrophysical explosions

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“…Since it can also be shown 24 that debris ions traveling too fast will slip through the ambient plasma without coupling, it is necessary to have a further constraint on the debris ions. We have shown previously in simulations 25 that for a debris plasma dominated by a single ion species (see Sec. IV A for further discussion), the condition R M =q d > 0:7, where q d is the debris ion gyroradius, must be satisfied for a shock to form.…”

Section: Theory and Simulationsmentioning

confidence: 91%

Laser-driven, magnetized quasi-perpendicular collisionless shocks on the Large Plasma Device

et al. 2014

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Articles you may be interested inVisualizing electromagnetic fields in laser-produced counter-streaming plasma experiments for collisionless shock laboratory astrophysicsa) Phys. Plasmas 20, 056313 (2013); 10.1063/1.4804548Ion acceleration from laser-driven electrostatic shocksa) Phys. Plasmas 20, 056304 (2013);The interaction of a laser-driven super-Alfv enic magnetic piston with a large, preformed magnetized ambient plasma has been studied by utilizing a unique experimental platform that couples the Raptor kJ-class laser system [Niemann et al., J. Instrum. 7, P03010 (2012)] to the Large Plasma Device [Gekelman et al., Rev. Sci. Instrum. 62, 2875] at the University of California, Los Angeles. This platform provides experimental conditions of relevance to space and astrophysical magnetic collisionless shocks and, in particular, allows a detailed study of the microphysics of shock formation, including piston-ambient ion collisionless coupling. An overview of the platform and its capabilities is given, and recent experimental results on the coupling of energy between piston and ambient ions and the formation of collisionless shocks are presented and compared to theoretical and computational work. In particular, a magnetosonic pulse consistent with a low-Mach number collisionless shock is observed in a quasi-perpendicular geometry in both experiments and simulations. V C 2014 AIP Publishing LLC.

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“…Recentry, Niemann et al have reported the first observation [45,46] of collisionless MHD perpendicular shock, which was predicted by hybrid-simulation [47], using the Large Plasma Device [48] and a high-energy laser system [49]. No clear particle acceleration has been investigated experimentally for the MHD shock yet.…”

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Collisionless electrostatic shock generation using high-energy laser systems

Sakawa

Morita

Kuramitsu

et al. 2016

Advances in Physics: X

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Collisionless shock is ubiquitous in space and astrophysical plasmas, and is believed to be a source of cosmic rays. In this review article, historical achievements of three different types of collisionless shocks, i.e. magnetohydrodynamic, electromagnetic, and electrostatic (ES) shocks, in theory/simulation, observation in space and astrophysical plasmas, and laboratory experiments are shown. An overview is given on recent progress of collisionless ES shock experiments using high-energy laser systems for two schemes. One is an interaction between laser-produced highdensity ablating plasma and a low-density ambient plasma, and the other is an interaction between laser-ablated counterstreaming plasmas using double-plane target. For the former scheme, detailed measurements of structures of collisionless ES shock and ion-acoustic soliton, and the transition from double-layer to collisionless ES shock are conducted by proton radiography. For the latter scheme, optical diagnostics are used to observe global structures of plasmas and shocks; collective laser Thomson scattering method is applied to clarify local plasma parameters, such as electron and ion temperatures, flow velocity, and electron density; and proton radiography is employed to measure a shock electric field. The measured large density-jump, steepening of self-emission profile, plasma parameters in the upand down-stream regions of a shock, and the narrow width of the shock electric field compared with the ion-ion Coulomb meanfree-path reveal the evidence for the formation of collisionless ES shock. ARTICLE HISTORY

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Hybrid simulation of shock formation for super-Alfvénic expansion of laser ablated debris through an ambient, magnetized plasma

Cited by 31 publications

References 30 publications

Collisionless momentum transfer in space and astrophysical explosions

Collisionless momentum transfer in space and astrophysical explosions

Laser-driven, magnetized quasi-perpendicular collisionless shocks on the Large Plasma Device

Collisionless electrostatic shock generation using high-energy laser systems

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