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Experimental Study of Hall Effect on a Formation Process of an FRC by Counter-Helicity Spheromak Merging in TS-4

Yasuhiro KAMINOU, Michiaki INOMOTO and Yasushi ONO

Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan

(Received 29 November 2015 / Accepted 2 March 2016 / Published 26 May 2016)

Abstract

Hall effect on counter-helicity spheromak merging is experimentally investigated in a low-S^∗ region, where S^∗ is the ratio of plasma minor radius to ion skin depth. Direct measurement of magnetic field, ion flow, electron density revealed that Hall effect affect not only merging reconnection phase but also relaxation phase through formation of ion flow and current density profiles. Hall effect breaks the symmetry of the "case-O" and "case-I" counter-helicity spheromak merging, which are defined by combinations of poloidal flux and toroidal flux of initial spheromaks. Formation of toroidal current profile and radial outflow pattern are different in case-O and case-I during merging process, and that results in great difference of profiles of electron density after merging.

Copyright (c) 2016 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

magnetic reconnection, field-reversed configuration, hall effect, plasma merging, spheromak, high-beta

DOI: 10.1585/pfr.11.2401052

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