Ion Acceleration and Direct Ion Heating in Three-Component Magnetic Reconnection

Ono, Yasushi; Yamada, Masaaki; Akao, T.; Tajima, T.; Matsumoto, Ryoji

doi:10.1103/physrevlett.76.3328

Cited by 211 publications

(177 citation statements)

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“…In the pioneering UCLA experiments, ion acceleration, possibly reduced by wave turbulence [7], and electron heating [8] were observed. However, ion heating could not be addressed because these experiments were in the "electron MHD" regime in which ρ i L. In TS-3 at the University of Tokyo, toroidal Alfvénic flows were believed to be accelerated by a "slingshot effect" of reconnected field lines, and global ion heating was attributed to thermalization of the sheared Alfvénic flows [9]. In SSX (Swarthmore Spheromak Experiment), Alfvénic ion jets correlated with reconnection were reported based on measurements of ion flux at the vacuum wall [10].…”

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confidence: 99%

Local Measurement of Nonclassical Ion Heating during Magnetic Reconnection

et al. 2000

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Local ion temperature is measured directly in the well-characterized reconnection layer of a laboratory plasma. These measurements demonstrate definitively that ions are heated due to reconnection and that more than half of the reconnected field energy is converted to ion kinetic energy. Neither classical Ohmic dissipation nor thermalization of energetic flows is sufficent to account for the energy converted, suggesting the importance of non-classical dissipation mechanisms such as wave-particle interactions.PACS numbers: 52.30. Jb, 96.60.Rd, 94.30.Lr Typeset using REVT E X 1

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Local Measurement of Nonclassical Ion Heating during Magnetic Reconnection

et al. 2000

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“…Gekelman & Stenzel (1985) also studied the anisotropy of the electron distribution in the reconnection layer using a novel electrostatic electron energy analyzer and found an energetic electron tail along the X-line. Ono et al (1996) observed ion outflow up to the Alfvén speed by Doppler shifts of impurity lines in an MHD plasma. Measurements were made with a polychrometer along a chord that could be scanned radially.…”

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“…Several laboratory experiments have measured energetic particles in reconnection geometries, but the emphasis has been on sub-Alfvénic outflow in the two-dimensional plane (Kornack, Sollins, & Brown 1998;Gekelman, Stenzel, & Wild 1982;Ono et al 1996). We previously observed an Alfvénic ion jet correlated with a reconnection event measured with a onedimensional probe .…”

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Experimental Observation of Energetic Ions Accelerated by Three-dimensional Magnetic Reconnection in a Laboratory Plasma

Brown

Cothran

Landreman

et al. 2002

The Astrophysical Journal

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Magnetic reconnection is widely believed responsible for heating the solar corona as well as for generating X-rays and energetic particles in solar flares. On astrophysical scales, reconnection in the intergalactic plasma is a prime candidate for a local source (!100 Mpc) of cosmic rays exceeding the Greisen-Zatsepin-Kúzmin cutoff (∼10 19 eV). In a laboratory astrophysics experiment, we have made the first observation of particles accelerated by magnetic reconnection events to energies significantly above both the thermal and the characteristic magnetohydrodynamic energies. These particles are correlated temporally and spatially with the formation of threedimensional magnetic structures in the reconnection region.

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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.…”

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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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Ion Acceleration and Direct Ion Heating in Three-Component Magnetic Reconnection

Abstract: Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. Ion acceleration and direct ion heating in three-component magnetic reconnection

Cited by 211 publications

References 15 publications

Local Measurement of Nonclassical Ion Heating during Magnetic Reconnection

Local Measurement of Nonclassical Ion Heating during Magnetic Reconnection

Experimental Observation of Energetic Ions Accelerated by Three-dimensional Magnetic Reconnection in a Laboratory Plasma

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

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