Surprise finding: Discovering a previously unknown role for a source of magnetic fields
The findings could improve understanding of a universal process that can disrupt cell phone service and power grids.
By John Greenwald, PPPL
Magnetic forces ripple throughout the universe, from the fields surrounding planets to the gasses filling galaxies, and can be launched by a phenomenon called the Biermann battery effect. Now scientists at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have found that this phenomenon may not only generate magnetic fields, but can sever them to trigger magnetic reconnection – a remarkable and surprising discovery.
The Biermann battery effect, a possible seed for the magnetic fields pervading our universe, arises in plasmas —the state of matter composed of free electrons and atomic nuclei — when the plasma temperature and density are misaligned. The tops of such plasmas might be hotter than the bottoms, and the density might be greater on the left side than on the right. This misalignment gives rise to an electromotive force that generates current that leads to magnetic fields. The process is named for Ludwig Biermann, a German astrophysicist who discovered it in 1950.
Revealed through computer simulations
The new findings reveal through computer simulations a previously unknown role for the Biermann effect that could improve understanding of reconnection — the snapping apart and violent reconnection of magnetic field lines in plasmas that gives rise to northern lights, solar flares and geomagnetic space storms that can disrupt cell-phone service and electric grids on Earth.
The results “provide a new platform for replicating in the laboratory the reconnection observed in astrophysical plasmas,” said Jackson Matteucci, a graduate student in the Program in Plasma Physics at PPPL and lead author of a description of the process in Physical Review Letters. Coauthors of the paper include his thesis advisers, Will Fox of PPPL and Amitava Bhattacharjee, head of the PPPL Theory Department, and researchers from other laboratories.