Observation of Ion Acceleration and Heating during Collisionless Magnetic Reconnection in a Laboratory Plasma

Yoo, Jongsoo; Yamada, Masaaki; Ji, Hantao; Myers, C. E.

doi:10.1103/physrevlett.110.215007

Cited by 63 publications

(65 citation statements)

References 36 publications

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“…Plasmas 22, 101205 (2015) electric field along magnetic field lines on the upstream side of the separatrix region is also different from the electron surfing mechanism proposed by Hoshino, 18 which did not consider the parallel electric field effect associated with the quadrupole B z generation. Our results of ion acceleration/ heating mainly by the inductive electric field are also different from the conclusion drawn in the previous papers 4,5 that the ions are mainly accelerated byẼ es across the field line separatrix into the downstream.…”

Section: -19contrasting

confidence: 56%

“…Magnetic reconnection has been observed in laboratory experiments [1][2][3][4][5] and space observations. [6][7][8][9][10][11][12][13][14] The magnetic reconnection problem has been extensively studied in the last 40 years using the single-fluid magneto-hydrodynamic (MHD) model, the Hall-MHD model, the two-fluid model, and the full kinetic particle-in-cell (PIC) simulation model.…”

Section: Introductionmentioning

confidence: 99%

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Physical processes of driven magnetic reconnection in collisionless plasmas: Zero guide field case

et al. 2015

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The key physical processes of the electron and ion dynamics, the structure of the electric and magnetic fields, and how particles gain energy in the driven magnetic reconnection in collisionless plasmas for the zero guide field case are presented. The key kinetic physics is the decoupling of electron and ion dynamics around the magnetic reconnection region, where the magnetic field is reversed and the electron and ion orbits are meandering, and around the separatrix region, where electrons move mainly along the field line and ions move mainly across the field line. The decoupling of the electron and ion dynamics causes charge separation to produce a pair of in-plane bipolar converging electrostatic electric field (E→es) pointing toward the neutral sheet in the magnetic field reversal region and the monopolar E→es around the separatrix region. A pair of electron jets emanating from the reconnection current layer generate the quadrupole out-of-plane magnetic field, which causes the parallel electric field (E→||) from E→ind to accelerate particles along the magnetic field. We explain the electron and ion dynamics and their velocity distributions and flow structures during the time-dependent driven reconnection as they move from the upstream to the downstream. In particular, we address the following key physics issues: (1) the decoupling of electron and ion dynamics due to meandering orbits around the field reversal region and the generation of a pair of converging bipolar electrostatic electric field (E→es) around the reconnection region; (2) the slowdown of electron and ion inflow velocities due to acceleration/deceleration of electrons and ions by E→es as they move across the neutral sheet; (3) how the reconnection current layer is enhanced and how the orbit meandering particles are accelerated inside the reconnection region by E→ind; (4) why the electron outflow velocity from the reconnection region reaches super-Alfvenic speed and the ion outflow velocity reaches Alfvenic speed; (5) how the quadrupole magnetic field is produced and how E→|| is produced; (6) how electrons and ions are accelerated by E→|| around the separatrix region; (7) why electrons have a flat-top parallel velocity distribution in the upstream just outside the reconnection region as observed in the magnetotail; (8) how electron and ion dynamics decouple and how the monopolar electrostatic electric field is produced around the separatrix region; (9) how ions gain energy as they move across the separatrix region into the downstream and how the ion velocity distribution is thermalized in the far downstream; and (10) how electrons move across the separatrix region and in the downstream and how the electron velocity distribution is thermalized in the far downstream. Finally, the main energy source for driving magnetic reconnection and particle acceleration/heating is the inductive electric field, which accelerates both electrons and ions around the reconnection current layer and separatrix regions.

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Section: -19contrasting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Physical processes of driven magnetic reconnection in collisionless plasmas: Zero guide field case

et al. 2015

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“…Very recently, a strong potential well has also been detected in Magnetic Reconnection eXperiment (MRX). 10 These observations appear to be in agreement with the theoretical models regarding the particle dynamics of the reconnection layer. We plan to address this primary issue as a focal point of the upcoming phase of our research and I am looking forward to productive collaboration with all members of the reconnection research community.…”

supporting

confidence: 85%

Preface to Special Topic Section: Advances in Magnetic Reconnection Research in Space and Laboratory Plasmas. Part II

Ono

Matsumoto

2013

Physics of Plasmas

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“…Since 1986 the merging of two toroidal plasmas (flux tubes) has been studied in a number of experiments: TS-3 [6] [7], START [8], MRX [9], SSX [10], VTF [11], TS-4 [12], UTST [13] [14], and MAST [15]. For those laboratory experiments, evidence of plasma acceleration toward outflow direction were observed as split line-integrated distribution function in 0D [16], 1D and 2D bidirectional toroidal acceleration during counter helicity spheromak merging [17] [18], and in-plane Mach probe measurement around X point with and without guide field [19][20] [21]. In the recent TS-3 experiment, with upgrade of diagnostics [22], 2D ion and electron heating characteristics are revealed [23] as bulk heating of ions at the downstream region and localized small electron heating around X point.…”

mentioning

confidence: 99%

Electron and Ion Heating Characteristics during Magnetic Reconnection in the MAST Spherical Tokamak

Tanabe

Yamada²,

Watanabe

et al. 2015

Phys. Rev. Lett.

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Local electron and ion heating characteristics during merging reconnection startup on the MAST spherical tokamak have been revealed for the first time using a 130 channel YAG-TS system and a new 32 chord ion Doppler tomography diagnostic. 2D local profile measurement of Te, ne and Ti detect highly localized electron heating at the X point and bulk ion heating downstream. For the push merging experiment under high guide field condition, thick layer of closed flux surface formed by reconnected field sustains the heating profile for more than electron and ion energy relaxation time τ E ei ∼ 4 − 10ms, both heating profiles finally form triple peak structure at the X point and downstream. Toroidal guide field mostly contributes the formation of peaked electron heating profile at the X point. The localized heating increases with higher guide field, while bulk downstream ion heating is unaffected by the change in the guide field under MAST conditions (Bt > 3Brec).PACS numbers: 52.35. Vd, 52.55.Fa, 52.72.+v Magnetic reconnection is a fundamental process which converts the magnetic energy of reconnecting fields to kinetic and thermal energy of plasma through the breaking and topological rearrangement of magnetic field lines. Recent satellite observations of solar flares revealed several important signatures of reconnection heating. In the solar flares, hard X-ray spots appear at loop-tops of coronas together with another two foot-point spots on the photosphere. The loop-top hot spots are considered to be caused by fast shocks formed in the down-stream of reconnection outflow [3]. The two-dimensional (2D) measurements of the Hinode spectrometer documented a significant broadening of Ca line-width downstream of reconnection [4]. These phenomena strongly suggest direct ion heating by reconnection outflow. On the other hand, the V-shape high electron temperature region was found around X-line of reconnection as an possible evidence of slow shock structure [5]. However, those heating characteristics of reconnection are still under serious discussion, indicating that direct evidence for the reconnection heating mechanisms should be provided by a proper laboratory experiment. Since 1986 the merging of two toroidal plasmas (flux tubes) has been studied in a number of experiments: TS-3

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Observation of Ion Acceleration and Heating during Collisionless Magnetic Reconnection in a Laboratory Plasma

Cited by 63 publications

References 36 publications

Physical processes of driven magnetic reconnection in collisionless plasmas: Zero guide field case

Physical processes of driven magnetic reconnection in collisionless plasmas: Zero guide field case

Preface to Special Topic Section: Advances in Magnetic Reconnection Research in Space and Laboratory Plasmas. Part II

Electron and Ion Heating Characteristics during Magnetic Reconnection in the MAST Spherical Tokamak

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