NERSC's Impact on Advances of Global Gyrokinetic PIC Codes for Fusion Energy Research

The National Energy Research Scientific Computing Center (NERSC) was originally launched as a computing center for the exclusive support of magnetic confinement fusion research in the US. There is, thus, a long history of computational advances and successes that ties fusion scientists with NERSC and its staff. One example of the numerous computational achievements enabled by NERSC in this field is the development of the global gyrokinetic particle-in-cell approach for the simulation of turbulent transport in tokamak fusion devices. This article describes the historical evolution of this method and the codes implementing it, and the impact that NERSC had in their development and the scientific discoveries that they allow.