The discovery of unexpected electrical currents arising in plasma within tokamaks may provide a new route to the stabilization of fusion reactions. U.S. Department of Energy's Princeton Plasma Physics Laboratory researchers observed the currents when electromagnetic waves formed spontaneously.

A high frequency electromagnetic wave causes some electrons to move forward and others backward. The two motions cancel each other out and no current occurs. A low frequency wave pushes forward on the electrons An artist's rendering of electrical current flowing through a tokamak fusion facility. Source: Elle Starkmanand backward on the atomic nuclei, producing a net electrical current.

A mathematical analysis of this phenomenon will provide tools for calculating how these currents evolve and how these ion acoustic waves might be harnessed to drive any current in plasma and stabilize fusion energy systems. A simple, general formula for this driven current was derived and used to show how currents can be driven for Langmuir waves in electron-positron-ion plasmas, and for ion-acoustic waves in electron-ion plasmas.

"There are magnetic fields throughout the universe on different scales, including the size of galaxies, and we don't really know how they got there," said Ian Ochs, graduate student in Princeton University's Program in Plasma Physics. "The mechanism we discovered could have helped seed cosmic magnetic fields, and any new mechanisms that can produce magnetic fields are interesting to the astrophysics community."