Electron magnetic reconnection without ion coupling in Earth's turbulent magnetosheath.

Academic Article

Abstract

  • Magnetic reconnection in current sheets is a magnetic-to-particle energy conversion process that is fundamental to many space and laboratory plasma systems. In the standard model of reconnection, this process occurs in a minuscule electron-scale diffusion region1,2. On larger scales, ions couple to the newly reconnected magnetic-field lines and are ejected away from the diffusion region in the form of bi-directional ion jets at the ion Alfvén speed3-5. Much of the energy conversion occurs in spatially extended ion exhausts downstream of the diffusion region 6 . In turbulent plasmas, which contain a large number of small-scale current sheets, reconnection has long been suggested to have a major role in the dissipation of turbulent energy at kinetic scales7-11. However, evidence for reconnection plasma jetting in small-scale turbulent plasmas has so far been lacking. Here we report observations made in Earth's turbulent magnetosheath region (downstream of the bow shock) of an electron-scale current sheet in which diverging bi-directional super-ion-Alfvénic electron jets, parallel electric fields and enhanced magnetic-to-particle energy conversion were detected. Contrary to the standard model of reconnection, the thin reconnecting current sheet was not embedded in a wider ion-scale current layer and no ion jets were detected. Observations of this and other similar, but unidirectional, electron jet events without signatures of ion reconnection reveal a form of reconnection that can drive turbulent energy transfer and dissipation in electron-scale current sheets without ion coupling.
  • Authors

  • Phan, TD
  • Eastwood, JP
  • Shay, MA
  • Drake, JF
  • Sonnerup, BUÖ
  • Fujimoto, M
  • Cassak, PA
  • Øieroset, M
  • Burch, JL
  • Torbert, Roy
  • Rager, AC
  • Dorelli, JC
  • Gershman, DJ
  • Pollock, C
  • Pyakurel, PS
  • Haggerty, CC
  • Khotyaintsev, Y
  • Lavraud, B
  • Saito, Y
  • Oka, M
  • Ergun, RE
  • Retino, A
  • Le Contel, O
  • Argall, MR
  • Giles, BL
  • Moore, TE
  • Wilder, FD
  • Strangeway, RJ
  • Russell, CT
  • Lindqvist, PA
  • Magnes, W
  • Status

    Publication Date

  • May 2018
  • Published In

    Digital Object Identifier (doi)

    Pubmed Id

  • 29743689
  • Start Page

  • 202
  • End Page

  • 206
  • Volume

  • 557
  • Issue

  • 7704