A Parallel Grad-Shafranov Solver for Real-Time Control of Tokamak Plasmas

To achieve real-time control of fusion plasmas, the flux distribution and derived quantities have to be calculated within the time of the machine control cycle, which in the case of the ASDEX-Upgrade experiment can be as small as 1 ms. To this end we have developed a fast numerical solver for the Grad-Shafranov equation, which allows exploitation of the parallel capabilities of modern multicore processors. Our implementation, termed GPEC (Garching parallel equilibrium code), is based entirely on open-source software components. For a numerical grid of size 32 × 64, our new code requires only 0.04 ms (0.11 ms for 64 × 128) for a single call of the Grad-Shafranov solver using a standard Intel Xeon quad-core CPU (3.2 GHz). We also show the first GPEC benchmark results obtained on the Intel Sandy Bridge eight-core server processor and demonstrate the relevance of the new solver for application in plasma equilibrium codes.