TITLE: Self organization in magnetized plasmas

SPEAKER: Professor Michael Brown,

TIME: Thursday Apr. 20, 2006 at 4:00 PM

PLACE: George P. Williams, Jr. Lecture Hall, (Olin 101)

It is a common process in the universe for plasma and magnetic fields to evolve together in a turbulent way but then rapidly relax to simple, self-organized structures. Solar flares erupt from the photosphere tangled and chaotic, but via a process called magnetic reconnection, they relax and straighten. This process releases energy in the form of superheated plasma and rapidly flowing jets. On a much larger scale (millions of light years), galactic disks collapse, rapidly shedding angular momentum and in the process generate extended magnetized jets along their axes. On human scales, laboratory experiments are underway seeking self-organized magnetic structures that would be suitable "bottles" for a fusion reactor. We present recent experimental results from the merger of two rings of hot, magnetized plasma in the Swarthmore Spheromak Experiment (SSX). During the merging process, the plasma self-organizes to generate a single, large scale (ρ = 0.2m, L=0.6 m), three-dimensional magnetic structure called a field-reversed configuration (FRC). The rate at which the merging proceeds is governed locally by magnetic reconnection in which magnetic fields associated with each ring become shared. The magnetic reconnection rate is fast and fully three-dimensional. Magnetic reconnection converts magnetic energy to heat (up to T=10⁶ K), energetic particles (E>100eV), and flow (up to 100 km/s). See http://plasma.physics.swarthmore.edu/selforg/index.html for more information.

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