Spontaneous focusing of plasma flow in a weak perpendicular magnetic field

Moritaka, Toseo; Kuramitsu, Yasuhiro; Liu, Yao Li; Chen, Shih Hung

doi:10.1063/1.4942028

Cited by 16 publications

(10 citation statements)

References 52 publications

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“…Experimental measurements need to verify that the flux is truly frozen to the plasma, to distinguish it from the case of interactions of unmagetized plasmas in the presence of an external magnetic field. It can also be challenging to ensure that the field penetrates uniformly, rather than seeding density, temperature and flux anisotropy during the interaction of the initially separate components [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Interactions of magnetized plasma flows in pulsed-power driven experiments

Suttle

Burdiak

Cheung

et al. 2019

Plasma Phys. Control. Fusion

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A supersonic flow of magnetized plasma is produced by the application of a 1 MA-peak, 500 ns current pulse to a cylindrical arrangement of parallel wires, known as an inverse wire array. The plasma flow is produced by the × acceleration of the ablated wire material, and a magnetic field of several Tesla is embedded at source by the driving current. This setup has been used for a variety of experiments investigating the interactions of magnetized plasma flows. In experiments designed to investigate magnetic reconnection, the collision of counter-streaming flows, carrying oppositely directed magnetic fields, leads to the formation of a reconnection layer in which we observe ions reaching temperatures much greater than predicted by classical heating mechanisms. The breakup of this layer under the plasmoid instability is dependent on the properties of the inflowing plasma, which can be controlled by the choice of the wire array material. In other experiments, magnetized shocks were formed by placing obstacles in the path of the magnetized plasma flow. The pile-up of magnetic flux in front of a conducting obstacle produces a magnetic precursor acting on upstream electrons at the distance of the ion inertial length. This precursor subsequently develops into a steep density transition via ion-electron fluid decoupling. Obstacles which possess a strong private magnetic field affect the upstream flow over a much greater distance, providing an extended bow shock structure.In the region surrounding the obstacle the magnetic pressure holds off the flow, forming a void of plasma material, analogous to the magnetopause around planetary bodies with self-generated magnetic fields.

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Section: Introductionmentioning

confidence: 99%

Interactions of magnetized plasma flows in pulsed-power driven experiments

Suttle

Burdiak

Cheung

et al. 2019

Plasma Phys. Control. Fusion

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“…We focus on electron dynamics by using a weak external field produced by a permanent magnet. Under the influence of this field, that is perpendicular to the plasma flow propagation axis, it can be collimated due to the distortion of the magnetic field 20 . We adjust the field strength so that the electrons are magnetized but not the ions, while we keep the system size much larger than the ion inertial length, , where c is the speed of light and ω pi is the ion plasma frequency.…”

Section: Introductionmentioning

confidence: 99%

Magnetic reconnection driven by electron dynamics

et al. 2018

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Magnetic reconnections play essential roles in space, astrophysical, and laboratory plasmas, where the anti-parallel magnetic field components re-connect and the magnetic energy is converted to the plasma energy as Alfvénic out flows. Although the electron dynamics is considered to be essential, it is highly challenging to observe electron scale reconnections. Here we show the experimental results on an electron scale reconnection driven by the electron dynamics in laser-produced plasmas. We apply a weak-external magnetic field in the direction perpendicular to the plasma propagation, where the magnetic field is directly coupled with only the electrons but not for the ions. Since the kinetic pressure of plasma is much larger than the magnetic pressure, the magnetic field is distorted and locally anti-parallel. We observe plasma collimations, cusp and plasmoid like features with optical diagnostics. The plasmoid propagates at the electron Alfvén velocity, indicating a reconnection driven by the electron dynamics.

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“…The electron moves along the distorted magnetic field rather than drift across the magnetic field and plasma is collimated. The collimation scenario is verified with particle-in-cell simulations 7,27 . The cusp and plasmoid propagation at electron Alfvén velocity with self-emission imaging indicates the magnetic reconnection at electron scale 7,[28][29][30] .…”

mentioning

confidence: 87%

Direct observations of pure electron outflow in magnetic reconnection

Sakai

Moritaka

Morita

et al. 2022

Sci Rep

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Magnetic reconnection is a universal process in space, astrophysical, and laboratory plasmas. It alters magnetic field topology and results in energy release to the plasma. Here we report the experimental results of a pure electron outflow in magnetic reconnection, which is not accompanied with ion flows. By controlling an applied magnetic field in a laser produced plasma, we have constructed an experiment that magnetizes the electrons but not the ions. This allows us to isolate the electron dynamics from the ions. Collective Thomson scattering measurements reveal the electron Alfvénic outflow without ion outflow. The resultant plasmoid and whistler waves are observed with the magnetic induction probe measurements. We observe the unique features of electron-scale magnetic reconnection simultaneously in laser produced plasmas, including global structures, local plasma parameters, magnetic field, and waves.

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Spontaneous focusing of plasma flow in a weak perpendicular magnetic field

Cited by 16 publications

References 52 publications

Interactions of magnetized plasma flows in pulsed-power driven experiments

Interactions of magnetized plasma flows in pulsed-power driven experiments

Magnetic reconnection driven by electron dynamics

Direct observations of pure electron outflow in magnetic reconnection

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