Large-scale gyrokinetic particle simulation of microturbulence in magnetically confined fusion plasmas

As the global energy economy makes the transition from fossil fuels toward cleaner alternatives, nuclear fusion becomes an attractive potential solution for satisfying growing needs. Fusion, the power source of the stars, has been the focus of active research since the early 1950s. While progress has been impressive - especially for magnetically confined plasma devices called tokamaks - the design of a practical power plant remains an outstanding challenge. A key topic of current interest is microturbulence, which is believed to be responsible for the unacceptably large leakage of energy and particles out of the hot plasma core. Understanding and controlling this process is of utmost importance for operating current devices and designing future ones. In addressing such issues, the Gyrokinetic Toroidal Code (GTC) was developed to study the global influence of mi.croturbulence on particle and energy confinement. It has been optimized on the IBM Blue Gene /L™ (BG/L) computer, achieving essentially linear scaling on more than 30,000 processors, A full simulation of unprecedented phase-space resolution was carried out with 32,768 processors on the BG/L supercomputer located at the IBM T. J. Watson Research Center, providing new insights on the influence of collisions on microturbulence.