The upgraded Large Plasma Device, a machine for studying frontier basic plasma physics

Gekelman, Walter; Pribyl, Patrick; Lucky, Z.; Drandell, M.; Leneman, D.; Maggs, J. E.; Vincena, S.; Compernolle, B. Van; Tripathi, Shreekrishna; Morales, G. J.; Carter, T. A.; Wang, Y.; DeHaas, T.

doi:10.1063/1.4941079

Cited by 121 publications

(87 citation statements)

References 65 publications

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“…1 2 condition, we anticipate a range of future applications to heliospheric, astrophysical, and possibly laboratory (Forest et al 2015;Gekelman et al 2016) plasmas.…”

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confidence: 99%

A Stringent Limit on the Amplitude of Alfvénic Perturbations in High-Beta Low-Collisionality Plasmas

Squire

Quataert

Schekochihin

2016

ApJL

107

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It is shown that low-collisionality plasmas cannot support linearly polarized shear-Alfvén fluctuations above a critical amplitude d b -B B 0 1 2 , where β is the ratio of thermal to magnetic pressure. Above this cutoff, a developing fluctuation will generate a pressure anisotropy that is sufficient to destabilize itself through the parallel firehose instability. This causes the wave frequency to approach zero, interrupting the fluctuation before any oscillation. The magnetic field lines rapidly relax into a sequence of angular zig-zag structures. Such a restrictive bound on shear-Alfvén-wave amplitudes has far-reaching implications for the physics of magnetized turbulence in the high-β conditions prevalent in many astrophysical plasmas, as well as for the solar wind at ∼1au where β1.

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“…1 2 condition, we anticipate a range of future applications to heliospheric, astrophysical, and possibly laboratory (Forest et al 2015;Gekelman et al 2016) plasmas.…”

mentioning

confidence: 99%

A Stringent Limit on the Amplitude of Alfvénic Perturbations in High-Beta Low-Collisionality Plasmas

Squire

Quataert

Schekochihin

2016

ApJL

107

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“…In our experiment, detailed in Fig. 1, a plastic target embedded in the Large Plasma Device (LAPD) 27 is irradiated by the Raptor high-energy laser 28 , producing an explosive carbon (C) and hydrogen (H) debris plasma that expands quasi-perpendicular to the magnetic field and through the steady-state, magnetized helium (He) plasma column generated by the LAPD. Under the experimental parameters, the initial perpendicular-to-B debris expansion speed of V d ≈ 600 km s −1…”

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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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“…A series of controlled laboratory experiments [27][28][29] were performed to study the excitation of whistler waves in the Large Plasma Device 30 at University of California, Los Angeles (UCLA). In the experiments, both electrostatic and whistler waves were excited by the injection of a gyrating electron beam into a cold plasma.…”

Section: Introductionmentioning

confidence: 99%

Electrostatic and whistler instabilities excited by an electron beam

Bortnik

Compernolle

et al. 2017

Physics of Plasmas

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The electron beam-plasma system is ubiquitous in the space plasma environment.Here, using a Darwin particle-in-cell method, the excitation of electrostatic and whistler instabilities by a gyrating electron beam is studied in support of recent laboratory experiments. It is assumed that the total plasma frequency ω pe is larger than the electron cyclotron frequency Ω e . The fast-growing electrostatic beam-mode waves saturate in a few plasma oscillations by slowing down and relaxing the electron beam parallel to the background magnetic field. Upon their saturation, the finite amplitude electrostatic beam-mode waves can resonate with the tail of the background thermal electrons and accelerate them to the beam parallel velocity. The slowergrowing whistler waves are excited in primarily two resonance modes: (a) through Landau resonance due to the inverted slope of the beam electrons in the parallel velocity; (b) through cyclotron resonance by scattering electrons to both lower pitch angles and smaller energies. It is demonstrated that, for a field-aligned beam, the whistler instability can be suppressed by the electrostatic instability due to a faster energy transfer rate between beam electrons and the electrostatic waves. Such a competition of growth between whistler and electrostatic waves depends on the ratio of ω pe /Ω e . In terms of wave propagation, beam-generated electrostatic waves are confined to the beam region whereas beam-generated whistler waves transport energy away from the beam. a) xinan@atmos.ucla.edu 1 arXiv:1707.05346v1 [physics.plasm-ph]

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The upgraded Large Plasma Device, a machine for studying frontier basic plasma physics

Cited by 121 publications

References 65 publications

A Stringent Limit on the Amplitude of Alfvénic Perturbations in High-Beta Low-Collisionality Plasmas

A Stringent Limit on the Amplitude of Alfvénic Perturbations in High-Beta Low-Collisionality Plasmas

Collisionless momentum transfer in space and astrophysical explosions

Electrostatic and whistler instabilities excited by an electron beam

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