At ASDEX upgrade (AUG) a new framework for the evaluation of impurity densities based on measurements from charge exchange recombination spectroscopy (CXRS) diagnostics has been developed. The charge exchange impurity concentration analysis code, or CHICA, can perform these calculations for all of the beam-based CXRS diagnostics at AUG and is equipped with the atomic data for all of the regularly measured charge exchange spectral lines (He, Li, B, C, N, O, and Ne). CHICA includes four different methods for the evaluation of the neutral density populations, which feature different implementations and contain varying levels of sophistication. These methods have been thoroughly benchmarked against one another, enabling the important processes for the evaluation of neutral densities to be identified as well as the neutral populations that are most critical to the accurate interpretation of the measured CXRS intensities. For the AUG neutral beams, charge exchange with the ground state of the first energy component is typically the dominant contribution to the measured CXRS intensities, but emission from reactions with the n = 2 beam halo population can contribute up to 35% to the total signal and must be included in the analysis. Neglect of this population leads to incorrect magnitudes and incorrect profile shapes of the calculated impurity density profiles. The edge lines of sight (LOS) of the core CXRS diagnostics at AUG intersect the edge pedestal inside of the neutral beam volume. Therefore, the impurity density is not constant along the LOS, complicating the interpretation of the measured intensities. Within CHICA a forward model for the edge impurity densities has been implemented, enabling the reconstruction of accurate edge profiles.
在ASDEX升级（AUG）装置上，开发了一种基于电荷交换复合光谱（CXRS）诊断测量来评估杂质密度的新框架。电荷交换杂质分析代码（CHICA）能够对AUG上所有基于束的CXRS诊断执行这些计算，并配备了所有常规测量的电荷交换谱线（He、Li、B、C、N、O和Ne）的原子数据。CHICA包含四种不同的中性粒子密度评估方法，这些方法具有不同的实现方式，并包含不同水平的复杂度。这些方法已相互进行了全面基准测试，从而确定了评估中性粒子密度的重要过程，以及对于准确解释所测CXRS强度最为关键的中性粒子布居。对于AUG的中性束，与第一能量分量的基态发生电荷交换通常是所测CXRS强度的主要贡献，但来自n=2束晕（beam halo）反应的发射可占总信号的35%，必须在分析中予以考虑。忽略这一布居会导致计算出的杂质密度剖面幅度不正确、形状错误。AUG芯部CXRS诊断的边缘视线（LOS）穿过中性束体积内部的边缘台基区。因此，杂质密度沿视线方向并非恒定，这使得对所测强度的解释变得复杂。在CHICA中，已实现了一个针对边缘杂质密度的正向模型，从而能够重建准确的边缘剖面。