title: Effect of ion skin depth on relaxation of merging spheromaks to a field-reversed configuration.
abstract: The effect of ion skin depth on the relaxation of merging spheromaks to a field-reversed configuration (FRC) is studied experimentally for a wide range of size parameter S* (ratio of minor radius to ion skin depth) from 1 to 7. The two merging spheromaks are observed to relax to an FRC or a new spheromak depending on whether the initial poloidal eigenvalue is smaller or larger than a threshold value. The bifurcation value is found to increase with decreasing size parameter S*, indicating that the low-S* condition provides a wide bifurcated range of relaxation to an FRC. The FRC-style relaxation under the low-S* conditions was accompanied by the suppression of the low-n modes (n is the toroidal mode number) activity. The fast rotations of the modes were followed by suppression of the low-n modes.
authors.affiliation: High Temperature Plasma Center, University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Eiichirou
authors.initials: E
authors.lastname: Kawamori
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ono