GS2 is a widely used, open source electromagnetic simulation code. The author of the original code was Mike Kotschenreuther, of the University of Texas. It was subsequently rewritten as a parallel code by Peter Liu and made nonlinear by Bill Dorland. Further improvements have been contributed by Emily Belli, Greg Hammett, Colin Roach, David Applegate, David Mikkelsen, Darin Ernst and others. There are currently more than 25 users around the world. GS2 development has been supported mainly by the Department of Energy, most recently through the Scientific Discovery Through Advanced Computing program.

More information, including source code and documentation is available on the web.