The purpose of the ITER Radial Neutron Camera (RNC) is the measurement of the plasma neutron emissivity profile [neutrons∙s m] for burn control purposes. The present RNC design consists of 22 collimated detector systems providing a set of line-integrated neutron measurements [neutrons∙s m] with full coverage of the plasma poloidal cross-section; the neutron emissivity can be recovered from the line-integrated measurements by means of dedicated reconstruction techniques (1D spatial inversion, 2D tomography). The present paper focuses on the evaluation of the improvement in the RNC 2D reconstruction of the neutron emissivity obtained by using the total neutron yield value provided by an independent diagnostic as additional constraint in the tomography procedure. The analysis was performed using a tomography code based on the Minimum Fisher Regularization (MFR). A clear improvement of the neutron emissivity reconstruction has been observed when the total neutron yield constraint is considered. The improvement is seen in: extension of the spatial region in which the accuracy of the reconstruction is better than 10 %; better reconstruction of peaked emissivity profiles; and robustness against measurements noise and line of sight data loss.

中文翻译：

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ITER 托卡马克 RNC 发射率重建中实施的总中子产额约束

ITER 径向中子相机 (RNC) 的用途是测量等离子体中子发射率分布 [neutrons∙s m]，以实现燃烧控制目的。目前的 RNC 设计由 22 个准直探测器系统组成，提供一组线积分中子测量 [neutrons∙s m]，完全覆盖等离子体极向截面；中子发射率可以通过专用重建技术（一维空间反演、二维断层扫描）从线积分测量中恢复。本文重点评估通过使用独立诊断提供的总中子产额值作为断层扫描过程中的附加约束来获得中子发射率的 RNC 二维重建的改进。使用基于最小费舍尔正则化 (MFR) 的断层扫描代码进行分析。当考虑总中子产额约束时，观察到中子发射率重建的明显改进。改进体现在： 空间区域的扩展，重建精度优于10%；更好地重建峰值发射率分布；以及针对测量噪声和视线数据丢失的鲁棒性。