Plasma and Fusion Research

Volume 14, 3401137 (2019)

Regular Articles

Horn-Shaped Structure Attached to the Ring-Shaped Ion Velocity Distribution during Magnetic Reconnection with a Guide Field
Shunsuke USAMI1,2), Ritoku HORIUCHI1,3) and Hiroaki OHTANI1,3)
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan
University of Tokyo, Tokyo 113-8654, Japan
Sokendai (The Graduate University of Advanced Studies), Toki 509-5292, Japan
(Received 9 January 2019 / Accepted 25 June 2019 / Published 20 August 2019)


The characteristic feature of a “horn-shaped velocity distribution” in magnetic reconnection in the presence of a guide field is investigated by means of simulation and theory. Particle simulations show that a horn-shaped velocity structure is formed in the downstream, concomitant with a ring-shaped velocity distribution studied in the preceding works. The theory which explains the motion of ions responsible for the horn-shaped structure is constructed as an extension of the basic theory for the ring-shaped structure. In the extended theory, ions are accelerated in the inflow direction by an electrostatic field in the separatrix, and thus the gyration speed of such ions in the downstream is larger than that for the basic theory. Test particle simulations confirm that some ions behave as in the extended theory and form the horn-shaped velocity structure.


particle simulation, magnetic reconnection, ion heating, PASMO, spherical tokamak

DOI: 10.1585/pfr.14.3401137


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