GS2 was initially the brainchild of Mike Kotschenreuther (at UT's Institute for Fusion Studies). Originally designed for comprehensive stability calculations, GS2 (or gks, as it was then known) was the first fully implicit gyrokinetic stability code. Successful benchmarks with the FULL code, an eigenvalue code with similar capabilities, were published in 1995 in Comp. Phys. Comm. Since then, GS2 (gks) has become the most widely used microstability analysis code in the world fusion program.
In the mid-1990's, Peter Liu rewrote the code, employing object-oriented principles and implementing parallelism. Together, Mike and Peter also built a sophisticated grid generation package for the field line and pitch angle coordinates, which enables efficient calculations in extreme geometries.
Since 1998, GS2 has been maintained mainly by Bill Dorland. Bill made the code nonlinear, enhanced the interfaces to numerical MHD equilibrium codes, and supported a wider distribution in the fusion community.
Today, GS2 continues to be developed. Bill Dorland, Greg Hammett, Steve Cowley, and Eliot Quataert are working on extensions necessary for the treatment of astrophysical plasma turbulence (for which anomalous heating rather than anomalous transport is of greatest interest). Others are making modifications to enable nonlinear gyrokinetic analyses of novel and/or non-axisymmetric configurations; to enable faster evaluation of anomalous diffusion coefficents; and to develop and test theoretical models of plasma turbulence.