On Multiple Reconnection X-Lines and Tripolar Perturbations of Strong Guide Magnetic Fields
2015 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 805, no 1, 43Article in journal (Refereed) Published
We report new multi-spacecraft Cluster observations of tripolar guide magnetic field perturbations at a solar wind reconnection exhaust in the presence of a guide field B-M. which is almost four times as strong as the reversing field B-L. The novel tripolar field consists of two narrow regions of depressed B-M, with an observed 7%-14% Delta B-M magnitude relative to the external field, which are found adjacent to a wide region of enhanced BM within the exhaust. A stronger reversing field is associated with each B-M depression. A kinetic reconnection simulation for realistic solar wind conditions and the observed strong guide field reveals that tripolar magnetic fields preferentially form across current sheets in the presence of multiple X-lines as magnetic islands approach one another and merge into fewer and larger islands. The simulated Delta B-M/Delta X-N over the normal width Delta X-N between a B-M minimum and the edge of the external region agree with the normalized values observed by Cluster. We propose that a tripolar guide field perturbation may be used to identify candidate regions containing multiple X-lines and interacting magnetic islands at individual solar wind current sheets with a strong guide field.
Place, publisher, year, edition, pages
2015. Vol. 805, no 1, 43
magnetic reconnection, plasmas, solar wind, Sun: heliosphere
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:uu:diva-256840DOI: 10.1088/0004-637X/805/1/43ISI: 000354991300043OAI: oai:DiVA.org:uu-256840DiVA: diva2:827180