Early-Time Model of Laser Plasma Expansion

Wright, Thomas P.

doi:10.1063/1.1693699

Cited by 42 publications

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“…(In the ρ d = 15 case, the peak density is about 14, but to clearly show the details of the cavity and the magnetic field‐debris ion interface at the cavity edge, we have clipped off the peak of the debris ion density profile.) The compression of the debris into a thin shell when the debris gyroradius is large occurs very early in the expansion and is related to the less magnetized response of the ions in this case [ Wright , 1971]. In both cases, the debris density falls rapidly to zero near the edge of the cavity.…”

Section: Two‐dimensional Simulations and Scalingmentioning

confidence: 99%

“…As the debris ions stream out radially from the explosive source, quasi‐neutrality requires that the electrons follow, leading to the formation of a diamagnetic cavity [ Wright , 1971] and compression of the excluded magnetic field at the edge of the cavity. As a result, some of the background ions can become reflected at the interface with the debris ions, at which conditions expressing momentum and energy conservation can be derived [ Forslund and Freidberg , 1971; Widner and Wright , 1972].…”

Section: Introductionmentioning

confidence: 99%

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Hybrid simulations of debris‐ambient ion interactions in astrophysical explosions

Winske

Gary

2007

J. Geophys. Res.

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[1] Hybrid simulations (particle ions, massless fluid electrons) have been carried out to study the super-Alfvenic expansion of a dense, hot debris plasma against a relatively tenuous, relatively cool magnetized ambient plasma for the purpose of modeling the physics relevant to the early phase of explosions in astrophysical environments (supernovae, solar flares). We examine the stopping of the debris ions, the spatial distribution of the stopped ions, and their penetration across the compressed ambient magnetic field, using simulations run in a two-dimensional geometry. The simulations show that the expanding debris excludes the ambient magnetic field to form a diamagnetic cavity. The stopping distance of the debris is consistent with that determined from the debris ions overrunning an equivalent mass of ambient ions. The distribution of the stopped debris ions is strongly dependent on the debris gyroradius based on the initial directed velocity r d , being highly peaked at the debris-magnetic field interface when r d is large. The distance that debris ions penetrate into and mix with the excluded magnetic field is measured and shown to increase linearly with r d .Citation: Winske, D., and S. P. Gary (2007), Hybrid simulations of debris-ambient ion interactions in astrophysical explosions,

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Section: Two‐dimensional Simulations and Scalingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hybrid simulations of debris‐ambient ion interactions in astrophysical explosions

Winske

Gary

2007

J. Geophys. Res.

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“…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.…”

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confidence: 99%

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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“…This mechanism was first confirmed experimentally at the stand KI-1 [Antonov et al, 1985] and afterwards in [Shaikhislamov et al, 2015]. The authors examined in more detail the main mechanism of magnetic laminar collisionless interaction -LP and BP electron exchange responsible in this case for the size R * (see Table) of a diamagnetic cavity [Wright, 1971]. As for TAW generation, an important property of MLM is the formation of vortex electric fields E φ , which accelerate background plasma ions along with the magnetic field frozen in it, on scales R * [Prokopov et al, 2016].…”

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confidence: 88%

On the possibility for laboratory simulation of generation of Alfvén disturbances in magnetic tubes in the solar atmosphere

Prokopov¹,

Захаров²,

Zakharov

et al. 2016

Solar-Terrestrial Physics

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_____________________________________________________________________________________ The paper deals with generation of Alfvén plasma disturbances in magnetic flux P.A. Prokopov, Yu.P. Zakharov, V.N. Tishchenko, E.L. Boyarintsev, A.V. Melekhov, A.G. Ponomarenko, V.G. Posukh, I.F. Shaikhislamov 20 INTRODUCTIONThe problem of heating of the solar corona is well known in solar research. The temperature of the solar surface (the photosphere) is approximately 5800 °C, whereas the temperature of the solar corona exceeds it by several orders of magnitude [Prist, 1985]. There are different hypotheses explaining the corona heating up to so high temperatures. One of the hypotheses assumes that energy is transferred from the solar surface to the corona by Alfvén waves (AW) or slow magnetosonic waves propagating in plasma. These waves propagate inside the plasma in the external magnetic field. Plasma particles move predominantly along magnetic field lines and, given sufficient field strength, form the so-called magnetic plasma tube along a magnetic field line.This paper presents the results of experimental simulation of plasma processes in tubes that begin and end in the photosphere, but are largely situated in the solar atmosphere (in the corona). The simulation experiments are generally used to study the generation of Alfvén and slow magnetosonic waves (and perhaps of accompanying shock waves) at the stand KI-1 with laser plasma blobs injected in a cone with ~1 sr opening and its axis along the magnetic field B 0 (initial configuration of the laser plasma (LP) cloud is a directional explosion). This is characteristic for generation and propagation of Alfvén and slow magnetosonic waves in the solar atmosphere. In addition, these experiments have provided data on fast high-frequency disturbanceselectron whistlers propagating in magnetic flux tubes at a velocity higher than the Alfvén velocity and preceding Alfvén and slow magnetosonic waves.One of the main objectives of these simulation experiments is to explore the possibility of generating torsional Alfvén waves (TAW) and their propagation in plasma structures imitating magnetic flux tubes in the solar atmosphere. Such waves induced by torsional movements (in azimuth) on the surface of the photosphere [Antolin, Shibata, 2010] are nowadays considered to be one of the most effective sources of corona heating [De Moortel, Nakaryakov, 2012;Antolin et al., 2015;Okamoto et al., 2015]. The new simulation experiments at the stand KI-1 have been initiated by calculations [Tishchenko, Shaikhislamov, 2010, 2014Tishchenko, et al. 2014 Tishchenko, et al. , 2015 of formation of cylindrical channels along a magnetic field (like a magnetic flux tube) with LP blobs propagating inside (together with their generated Alfvén and magnetosonic waves), as well as by results of previous experiments with LP [Antonov et al., 1985;Zakharov et al., 2006; Shaikhislamov et al., 2015] in simulation of different nonstationary processes in space plasma [Vshivkov et al., 1987;Brady et al., 2009;Dudn...

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Early-Time Model of Laser Plasma Expansion

Cited by 42 publications

References 0 publications

Hybrid simulations of debris‐ambient ion interactions in astrophysical explosions

Hybrid simulations of debris‐ambient ion interactions in astrophysical explosions

Collisionless momentum transfer in space and astrophysical explosions

On the possibility for laboratory simulation of generation of Alfvén disturbances in magnetic tubes in the solar atmosphere

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