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arXiv 2103.07581physics.plasm-ph
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轴对称等离子体的贝叶斯平衡态

Bayesian equilibria of axisymmetric plasmas

Sehyun Kwak, J. Svensson, O. Ford, L. Appel, Y. -c. Ghim, JET Contributors

AI总结:

本文提出一种贝叶斯方法,从磁场和压力测量中推断轴对称等离子体平衡态,利用高斯过程建模并引入MHD力平衡约束,通过吉布斯采样探索后验分布。

摘要:

我们提出了一种贝叶斯方法,用于从磁场和等离子体压力测量中推断轴对称等离子体平衡态。该方法计算与测量结果及磁流体动力学(MHD)力平衡相一致的所有可能的等离子体电流和压力分布解。环形等离子体电流和磁场线圈被建模为一组轴对称的载流固体束。其他参数如等离子体压力和极向电流通量被表示为极向磁通量的函数,该磁通量由给定的二维电流分布确定。等离子体压力和极向电流通量分布被建模为高斯过程,其平滑度基于奥卡姆剃刀原理最优选择。为了找到平衡解,我们将每个等离子体电流束处的MHD力平衡约束作为先验知识的一部分引入。给定所有这些物理量,由预测(正演)模型计算的诊断预测与观测结果进行比较。高维复杂的后验概率分布通过一种基于吉布斯采样方案的新算法进行探索。

英文摘要:

We present a Bayesian method for inferring axisymmetric plasma equilibria from the magnetic field and plasma pressure measurements. The method calculates all possible solutions for plasma current and pressure distributions consistent with the measurements and magnetohydrodynamic (MHD) force balance. Toroidal plasma current and magnetic field coils are modelled as a set of axisymmetric current-carrying solid beams. The other parameters such as plasma pressure and poloidal current flux are given as a function of poloidal magnetic flux, which is determined given a 2D current distribution. Plasma pressure and poloidal current flux profiles are modelled as Gaussian processes whose smoothness is optimally chosen based on the principle of Occam's razor. To find equilibrium solutions, we introduce an MHD force balance constraint at every plasma current beam as a part of the prior knowledge. Given all these physical quantities, predictions calculated by the predictive (forward) models for diagnostics are compared to the observations. The high dimensional complex posterior probability distribution is explored by a new algorithm based on the Gibbs sampling scheme.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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