AI 中文总结
本研究提出了一种用于计算精确视在体积几何矩阵的体素-探测器方法，通过TCV托卡马克的软X射线和 bolometry 系统验证，其重建质量优于视线近似，且相关例程已公开。
AI 中文摘要
从等离子体诊断数据进行发射率层析重建依赖于将等离子体发射率映射到测量信号的合成模型，该模型在等离子体成像领域被称为几何矩阵，通常采用视线（LoS）近似构建。这种近似忽略了探测器观测束的有限宽度，因此会引入系统误差；而物理上正确的视在体积（VoS）模型通过考虑观测束的完整三维范围消除了这种不准确性，但其应用有时因难以独立验证而受阻。我们提出了一种直观且易于检查的体素-探测器（V2D）方法，用于计算物理上精确的VoS几何矩阵，该方法基于将托卡马克 vessel 离散为体素，并估算每个体素对每个探测器测量值的贡献。我们将V2D方法应用于TCV托卡马克的软X射线（SXR）和 bolometry 系统，通过对物理真实发射率剖面的幻影研究，量化了使用VoS模型相比LoS模型在重建质量上的提升。我们发现VoS模型整体上提供了更好的精度和准确度，但有趣的是，更简单的LoS模型并未在估计的总辐射功率、芯部辐射功率、偏滤器辐射功率和主腔室辐射功率中引入显著的系统偏差。我们进一步将V2D几何矩阵与独立的射线追踪实现进行比较，发现二者一致性极佳，验证了两种方法可在TCV日常使用。本工作开发的所有例程均已公开提供。
英文摘要
Tomographic emissivity reconstruction from plasma diagnostics data relies on a synthetic model mapping the plasma emissivity to the measured signals. The model, referred to as a geometry matrix in the plasma imaging community, is often built using the line-of-sight (LoS) approximation. This approximation neglects the finite width of the detector viewing beams and can therefore introduce systematic errors. Physically correct volume-of-sight (VoS) models remove this inaccuracy by accounting for the full 3D extent of the viewing beams. Their adoption, however, is sometimes hindered by the difficulty of independently validating them. We present an intuitive and easily inspectable voxel-to-detector (V2D) approach for computing physically accurate VoS geometry matrices, based on discretizing the tokamak vessel into voxels and estimating the contribution of each voxel to the measurements of each detector. We apply the V2D approach to the soft X-ray (SXR) and bolometry systems of the TCV tokamak. Through phantom-based studies on physically realistic emissivity profiles, we quantify the improvement in reconstruction quality obtained by using VoS rather than LoS models. We find that the VoS model yields overall better accuracy and precision; however, interestingly, the simpler LoS model does not introduce a significant systematic bias in the estimated total, core, divertor and main chamber radiated powers. We further compare the V2D geometry matrix with an independent ray-tracing implementation, finding excellent agreement that validates both approaches for routine use at TCV. All routines developed in this work are made openly available.
