This Week at Physics

<< Fall 2011 Spring 2012 Fall 2012 >>

Event Number 2611

  Monday, February 20th, 2012

Plasma Physics (Physics/ECE/NE 922) Seminar
Impulsive Fast Reconnection via Flux Rope Dynamics
Time: 12:00 pm
Place: 2241 Chamberlin
Speaker: Hantao Ji, Princeton Plasma Physics Laboratory
Abstract: Magnetic reconnection, the efficient release of magnetic energy by topological rearrangement of field lines, is one of the most important and fundamental plasma processes in space, solar and more distant astrophysical plasmas. The modern collisionless models predict that ions exhaust through a thick, ion-scale layer while mobile electrons leave through a thin, electron-scale layer, allowing for efficient release of magnetic energy. While ion layers have been frequently detected in space and studied in detail in the laboratory, the dissipation on the electron scales near the X-line remains largely unknown. The discrepancies [1-3] between the measured thickness of the electron diffusion layer in MRX and best available 2D kinetic simulations suggest that the electron scale dissipation must be 3D in nature. In this talk, the most recent experimental results from MRX and their comparisons with 3D kinetic simulations will be discussed. It is found that impulsive fast reconnection is caused by a disruption of the current channel localized in 3D space, associated with a burst of electromagnetic fluctuations. There exists substantial evidence that these impulsive behaviors are caused by 3D flux rope dynamics [4]. Looking into the future, a new theme of multiple X-line reconnection in a phase diagram [5] possibly provides solutions for fast reconnection in large space and astrophysical systems and for efficient particle acceleration often observed there. Scientific opportunities for a next generation laboratory experiment based on MRX to study magnetic reconnection in such regimes directly relevant to space and astrophysical plasmas will be described.<br>
<br>
[1] H. Ji et al., GRL 35, L13106 (2008).<br>
[2] S. Dorfman et al., PoP 15, 102107 (2008).<br>
[3] V. Roytershteyn et al. PoP 17, 055706 (2010).<br>
[4] S. Dorfman, Ph. D. Thesis (2011); to be submitted to PRL (2012).<br>
[5] H. Ji and W. Daughton, PoP 18, 111207 (2011).<br>
Host: Cary Forest
Add this event to your calendar

©2013 Board of Regents of the University of Wisconsin System