GPEC: A Real-Time–Capable Tokamak Equilibrium Code
GPEC: A Real-Time–Capable Tokamak Equilibrium Code
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DOI：
10.13182/fst15-154
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发表时间：
2015-11
影响因子：
0.9
通讯作者：
M. Rampp;R. Preuss;R. Fischer
中科院分区：
文献类型：
--
作者：
M. Rampp;R. Preuss;R. Fischer
本文介绍了一种新的托卡马克等离子体并行平衡重建程序--Garching并行平衡程序（GPEC）。GPEC允许足够精确地计算平衡通量分布，以在1 ms的运行时间内导出等离子体控制参数，这使得ASDEX升级（AUG）实验和其他机器的控制周期至少为该大小的实时应用成为可能。底层算法基于完善的离线分析代码CLISTE，遵循迭代求解Grad-Shafranov方程并从实验中输入诊断信号的经典概念。新的代码采用了混合并行化计划计算的平衡通量分布和扩展的快速，共享内存并行泊松求解器，我们已经描述了由分布式计算的个人泊松问题对应于不同的基函数。代码完全基于开源软件组件，并在标准服务器硬件和软件环境上运行。GPEC的实时能力通过对取自典型AUG放电的1 s操作的1000个通量分布的序列执行离线计算并以1 ms的时间分辨率导出相关控制参数来证明。在当前服务器硬件上，新代码允许采用32 × 64区域的网格大小用于空间离散化和多达15个基函数。它考虑到大约90个诊断信号，同时使用多达四个平衡迭代和计算20多个等离子体控制参数，包括计算昂贵的安全系数q的至少四个不同水平的归一化通量。
Abstract A new parallel equilibrium reconstruction code for tokamak plasmas—the Garching Parallel Equilibrium Code (GPEC)—is presented. GPEC allows one to compute equilibrium flux distributions sufficiently accurate to derive parameters for plasma control within 1 ms of run time, which enables real-time applications at the ASDEX Upgrade (AUG) experiment and other machines with a control cycle of at least this size. The underlying algorithms are based on the well-established off-line–analysis code CLISTE, following the classical concept of iteratively solving the Grad-Shafranov equation and feeding in diagnostic signals from the experiment. The new code adopts a hybrid parallelization scheme for computing the equilibrium flux distribution and extends the fast, shared-memory-parallel Poisson solver that we have described previously by a distributed computation of the individual Poisson problems corresponding to different basis functions. The code is based entirely on open-source software components and runs on standard server hardware and software environments. The real-time capability of GPEC is demonstrated by performing an off-line computation of a sequence of 1000 flux distributions that are taken from 1 s of operation of a typical AUG discharge and deriving the relevant control parameters with a time resolution of 1 ms. On the current server hardware, the new code allows employing a grid size of 32 × 64 zones for the spatial discretization and up to 15 basis functions. It takes into account about 90 diagnostic signals while using up to four equilibrium iterations and computing more than 20 plasma-control parameters, including the computationally expensive safety factor q on at least four different levels of the normalized flux.