Measurements of Linear and Nonlinear Hall Reconnection

POSTER

Abstract

Previous measurements in MST have established that two-fluid Hall effects produce a dynamo during sawtooth relaxation events, and therefore two-fluid dynamics are important when evaluating the macroscopic effects of reconnection. This was established by measuring the nonlinear Hall term $(J_1 \times B_1)$ in the axisymmetric (flux-surface averaged) Ohm's Law. Here, we report measurements of terms in the non-axisymmetric Ohm's Law, including the \em linear \em Hall term, $(J_1 \times B_0 + J_0 \times B_1)$, and other spatially varying quantities. These measurements are a more direct indicator of the role of two-fluid effects on reconnection. Measurements are performed by probes in the vicinity of the reversal surface to measure reconnection associated with modes of poloidal mode number m=0. Results show that the linear Hall term is large compared to $\eta \widetilde{J}_{||}$, indicating the possibility of fast collisionless reconnection. Results are compared to a theoretical interpretation based on two-fluid MHD.

Authors

  • T.D. Tharp

  • A.F. Almagri

    University of Wisconsin-Madison, University of Wisconsin Madison

  • D. Craig

  • G. Fiksel

    University of Wisconsin-Madison

  • A. Kuritsyn

  • M.C. Miller

    University of Wisconsin - Madison and the CMSO

  • V.V. Mirnov

  • S.C. Prager

    University of Wisconsin - Madison, Center for Magnetic Self Organization in Laboratory and Astrophysical Plasmas, University of Wisconsin, University of Wisconsin-Madison, University of Wisconsin - Madison, University of Wisconsin, Madison

  • J.S. Sarff

    University of Wisconsin, and Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of Wisconsin-Madison, University of Wisconsin - Madison, UW-Madison, CMSO, University of Wisconsin, Madison, MST and CMSO at the University of Wisconsin-Madison