By employing Bayesian inference techniques, the full electron density profile from the plasma core to the edge of Wendelstein 7-X (W7-X) is inferred solely from neutral hydrogen beam and halo Balmer-α (Hα) emission data. The halo is a cloud of neutrals forming in the vicinity of the injected neutral beam due to multiple charge exchange reactions. W7-X is equipped with several neutral hydrogen beam heating sources and an Hα spectroscopy system that views these sources from different angles and penetration depths in the plasma. As the beam and halo emission form complex spectra for each spatial point that are non-linearly dependent on the plasma density profile and other parameters, a complete model from the neutral beam injection and halo formation through to the spectroscopic measurements is required. The model is used here to infer electron density profiles for a range of common W7-X plasma scenarios. The inferred profiles show good agreement with profiles determined by the Thomson scattering and interferometry diagnostics across a broad range of absolute densities without any changes to the input or fitting parameters. The time evolution of the density profile in a discharge with continuous core density peaking is successfully reconstructed, demonstrating sufficient spatial resolution to infer strongly shaped profiles. Furthermore, it is shown as a proof of concept that the model is also able to infer the main ion temperature profile using the same data set.

中文翻译：

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根据 Wendelstein 7-X 的中性束和晕 Balmer-α 发射对电子密度和离子温度分布进行贝叶斯推断

通过采用贝叶斯推理技术，从等离子体核心到 Wendelstein 7-X (W7-X) 边缘的完整电子密度分布仅根据中性氢束和晕 Balmer-α (Hα) 发射数据推断出来。光晕是由于多次电荷交换反应而在注入的中性束附近形成的中性云。 W7-X 配备了多个中性氢束加热源和 Hα 光谱系统，可以从等离子体中的不同角度和穿透深度观察这些源。由于光束和光晕发射形成每个空间点的复杂光谱，这些光谱非线性地依赖于等离子体密度分布和其他参数，因此需要一个从中性束注入和光晕形成到光谱测量的完整模型。该模型此处用于推断一系列常见 W7-X 等离子体场景的电子密度分布。推断的剖面与汤姆逊散射和干涉测量诊断在广泛的绝对密度范围内确定的剖面具有良好的一致性，而无需对输入或拟合参数进行任何更改。成功地重建了具有连续核心密度峰值的放电中密度分布的时间演化，证明了足够的空间分辨率来推断强形状的分布。此外，作为概念证明，该模型还能够使用相同的数据集推断主要离子温度分布。