University of Maryland
Atlantic Building, Room 2400
4:30 PM Monday, February 11, 2008
Coffee, Tea & Snacks 4:15-4:30 PM

James F. Drake
University of Maryland
Ion pickup and acceleration in magnetic reconnection exhausts

Energetic ions are produced during reconnection events in the solar atmosphere, the Earth's magnetosphere and in laboratory fusion experiments. We find that during magnetic reconnection ion acceleration occurs primarily as ions cross from upstream into the Alfvenic reconnection exhaust. Depending on the strength of the guide field, protons and higher mass particles behave like pickup particles in that they abruptly cross a narrow boundary layer and find themselves in a region of Alfvenic outflow. Their motion then mimics that of a classic pickup ion, gaining an Alfvenic ExB flow in the jet and a thermal speed close to the Alfven speed. The resulting ion energy is therefore proportional to mass as in many of the solar energetic particle observations. Preliminary analysis of Wind in-situ observations of solar wind reconnection exhausts supports this picture. A model of solar energetic ion production based on multiple encounters with reconnection exhausts is being pursued.

Sponsored by: Department of Physics and the Institute for Physical Science and Technology, University of Maryland. For information call Victoria at (301) 405-4811 or go to the UMD Space Physics group seminar web site.

There is free parking after 4:00 PM in lot B (the big parking garage across the street from the ATL building). There are a limited number of spaces in lot Q next to the new ATL wing with free parking after 4PM even when there is a basketball game on campus.