We present a fully Bayesian approach for the inference of radial profiles of impurity transport coefficients and compare its results to neoclassical, gyrofluid and gyrokinetic modeling. Using nested sampling, the Bayesian Impurity Transport InferencE (BITE) framework can handle complex parameter spaces with multiple possible solutions, offering great advantages in interpretative power and reliability with respect to previously demonstrated methods. BITE employs a forward model based on the pySTRAHL package, built on the success of the well-known STRAHL code [Dux, IPP Report, 2004], to simulate impurity transport in magnetically-confined plasmas. In this paper, we focus on calcium (Ca, Z=20) Laser Blow-Off injections into Alcator C-Mod plasmas. Multiple Ca atomic lines are diagnosed via high-resolution X-ray Imaging Crystal Spectroscopy and Vacuum Ultra-Violet measurements. We analyze a sawtoothing I-mode discharge for which neoclassical and turbulent (quasilinear and nonlinear) predictions are also obtained. We find good agreement in diffusion across the entire radial extent, while turbulent convection and density profile peaking are estimated to be larger in experiment than suggested by theory. Efforts and challenges associated with the inference of experimental pedestal impurity transport are discussed.

中文翻译：

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Alcator C-Mod 上实验径向杂质传输的推断：贝叶斯参数估计和模型选择

我们提出了一种完全贝叶斯方法来推断杂质传输系数的径向分布，并将其结果与新古典、陀螺流体和陀螺动力学模型进行比较。使用嵌套采样，贝叶斯杂质传输推理 (BITE) 框架可以处理具有多种可能解决方案的复杂参数空间，相对于先前演示的方法，在解释能力和可靠性方面具有巨大优势。BITE 采用基于 pySTRAHL 包的前向模型，建立在著名的 STRAHL 代码 [Dux，IPP 报告，2004] 的成功基础上，以模拟磁约束等离子体中的杂质传输。在本文中，我们关注钙 (Ca, Z=20) 激光吹离注入 Alcator C-Mod 等离子体。通过高分辨率 X 射线成像晶体光谱和真空紫外测量诊断多条 Ca 原子线。我们分析了锯齿形 I 模式放电，还获得了新古典和湍流（准线性和非线性）预测。我们发现在整个径向范围内的扩散具有良好的一致性，而在实验中估计湍流对流和密度分布峰值比理论建议的要大。讨论了与实验基座杂质传输推断相关的努力和挑战。而湍流对流和密度分布峰值在实验中估计比理论建议的要大。讨论了与实验基座杂质传输推断相关的努力和挑战。而湍流对流和密度分布峰值在实验中估计比理论建议的要大。讨论了与实验基座杂质传输推断相关的努力和挑战。