The Implementation of Real-Time Storage for Parallel Plasma Equilibrium Reconstruction Data in EAST PCS

Abstract

In order to obtain the accurate and fast equilibrium reconstruction for Experimental Advanced Superconducting Tokamak (EAST), parallel plasma equilibrium reconstruction (P-EFIT) based on parallel computation in the graphic processing unit (GPU) and the EFIT framework is developed. However, more data will be produced during shots with improved accuracy and rapidity. 76 KB of P-EFIT data are generated in each iteration of $500~\mu \text{s}$ with computation grid size of $129 \times 129$ . EAST is aimed at 1000-s-long-pulse discharge, then 52 GB of P-EFIT data will be generated during a shot even at 1.5 ms saving interval. In the previous storage mode, these data will be saved in memory during shots and archived to MDSplus as a whole after the shot, which means a very large memory requirement and heavy network transmission load after shots. Therefore, the real-time storage is designed for P-EFIT data to replace the “after shot archiving” mode. In the new mode, the P-EFIT processes and real-time archiving process will coordinate and share P-EFIT data gathered from GPU via shared memory, then the P-EFIT data will be archived to MDSplus in real-time during shots based on “segmented record” of MDSplus, which provides the possibility to reuse the memory allocated for P-EFIT and save data in higher saving frequency. The real-time storage of P-EFIT data was tested in 10-s discharge and 1000-s-long-pulse simulation discharge, and the validity and the advantage of memory saving have been verified. The real-time storage has been integrated into a plasma control system (PCS) and will be applied to next experiments in EAST. In order to obtain the accurate and fast equilibrium reconstruction for Experimental Advanced Superconducting Tokamak (EAST), parallel plasma equilibrium reconstruction (P-EFIT) based on parallel computation in the graphic processing unit (GPU) and the EFIT framework is developed. However, more data will be produced during shots with improved accuracy and rapidity. 76 KB of P-EFIT data are generated in each iteration of $500~\mu \text{s}$ with computation grid size of $129 \times 129$ . EAST is aimed at 1000-s-long-pulse discharge, then 52 GB of P-EFIT data will be generated during a shot even at 1.5 ms saving interval. In the previous storage mode, these data will be saved in memory during shots and archived to MDSplus as a whole after the shot, which means a very large memory requirement and heavy network transmission load after shots. Therefore, the real-time storage is designed for P-EFIT data to replace the “after shot archiving” mode. In the new mode, the P-EFIT processes and real-time archiving process will coordinate and share P-EFIT data gathered from GPU via shared memory, then the P-EFIT data will be archived to MDSplus in real-time during shots based on “segmented record” of MDSplus, which provides the possibility to reuse the memory allocated for P-EFIT and save data in higher saving frequency. The real-time storage of P-EFIT data was tested in 10-s discharge and 1000-s-long-pulse simulation discharge, and the validity and the advantage of memory saving have been verified. The real-time storage has been integrated into a plasma control system (PCS) and will be applied to next experiments in EAST.