Mean‐field plasma edge transport codes such as SOLPS‐ITER heavily rely on ad‐hoc radial diffusion coefficients to approximately model anomalous transport. Such coefficients are experimentally determined and vary between different machines, and also depend on the operational regime and plasma location within the same device. Therefore, to match experimental data the modeller is required to manually tune several free parameters in expensive simulations, and the code's predictive capabilities are significantly downgraded. As a solution, a new model has been developed for SOLPS‐ITER, solving an additional transport equation for the turbulent kinetic energy k, derived by consistently time‐averaging the Braginskii equations, and including a diffusive closure for the anomalous particle flux. This closure model relates the anomalous diffusion coefficient to the local k value. The resulting equation structure and its closure are inspired by TOKAM2D isothermal interchange turbulence simulation results. Within this model, fewer and hopefully more universal free parameters are retained, thus improving the code's predictive capabilities. The new model has been tested on a COMPASS case for which upstream plasma profiles were available. Experimental data and a reference solution, obtained by matching the profiles through manual tuning of radial diffusivities, have been used to estimate the parameters of our new transport model. A ballooned particle diffusivity profile is retrieved by the new radial transport model, thanks to the proposed interchange drive. The obtained upstream profiles qualitatively agree with the experiment and prove the new model is a promising first attempt to be further refined.

中文翻译：

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SOLPS-ITER的基于交换湍流的径向传输模型：COMPASS案例研究

诸如SOLPS-ITER之类的平均场等离子体边缘传输代码在很大程度上依赖于临时径向扩散系数来近似模拟异常传输。此类系数是通过实验确定的，并且在不同的机器之间会有所不同，并且还取决于同一设备内的操作方案和等离子体位置。因此，为了匹配实验数据，建模者需要在昂贵的仿真中手动调整几个自由参数，并且代码的预测能力会大大降低。作为解决方案，已经为SOLPS-ITER开发了一个新模型，解决了湍流动能k的附加输运方程，通过对Braginskii方程进行持续时间平均来得出，并且包括用于异常粒子通量的扩散封闭。该闭合模型将异常扩散系数与局部k关联值。所得的方程结构及其闭合式受到TOKAM2D等温交换湍流模拟结果的启发。在此模型中，保留了更少且希望更多的通用自由参数，从而提高了代码的预测能力。新模型已经在COMPASS机箱上进行了测试，该机箱具有上游血浆分布。实验数据和参考解决方案（通过手动调整径向扩散率来匹配轮廓）获得的参考数据已用于估算新运输模型的参数。由于提出了互换驱动，通过新的径向传输模型可以获取膨胀的颗粒扩散率曲线。获得的上游曲线在质量上与实验吻合，并证明新模型是有希望的进一步完善的首次尝试。