The tokamak `a configuration variable (TCV) is a small-sized tokamak, where finite size effects (often called 'rho-star' or 'global' effects) could significantly impact the heat and particle fluxes, leading to discrepancies between gyrokinetic flux-tube results and global ones (McMillan et al 2010 Phys. Rev. Lett.105 155001). The impact of global effects on the radial profile of the plasma density has been investigated in a previous study for a particular TCV discharge with negligible particle source, satisfying the 'zero particle flux' (ZPF) condition. A radially local flux-tube analysis, reconstructing the dependence of the peaking of the density profile on the main physical parameters, invoking the ZPF constraint, was pursued close to mid-radius in (Mariani et al 2018 Phys. Plasmas25 012313). This analysis was followed by a global one (Mariani et al 2019 Plasma Phys. Control. Fusion61 064005), where local quasi-linear (QL) and nonlinear (NL) results were compared with global simulations, showing small global effects on the density peaking. However, these gradient-driven (GD) global runs considered Krook-type heat and particle sources to keep temperature and density profiles fixed on average, which differ from the experimental radially localized sources. To remove this possible bias on the results, a different evaluation of the density peaking for the same case is performed here, based on global NL hybrid simulations where the temperature profiles are [still] kept fixed with the Krook-type sources, however the density profile relaxes in a flux-driven way (with zero particle source). The new hybrid simulations show a good agreement with the old GD runs. A global QL model is also developed and applied using the output from linear global runs, to estimate ratios of fluxes, showing a good agreement with the flux-tube results of global NL GD simulations. The effect of collisions on the results is also investigated, in order to evaluate their impact on the radial variation of the density peaking.
以下是将该学术摘要翻译为中文的版本，保留了原文的递归式结构： --- **摘要** 本文研究了全局回旋动理学模拟中等离子体密度峰化对主要物理参数的依赖关系。在先前针对特定托卡马克放电的研究中，在满足“零粒子通量”（ZPF）条件下，于近等离子体边缘处开展了局域通量管分析，以重构密度剖面的峰化程度与主要物理参数之间的依赖关系。该分析随后被推广至全局模拟，其中局域准线性（QL）与非线性（NL）结果与全局模拟进行了对比，结果表明全局效应对密度峰化的影响较小。然而，这些梯度驱动（GD）的全局模拟采用了克罗克型热源和粒子源以维持温度与密度剖面，其与实验观测的偏差促使研究者采用不同的评估方法。为此，在相同的条件下，基于全局非线性混合模拟重新评估了密度峰化，其中温度剖面仍保持固定，而密度剖面则允许在通量驱动（FD）框架下自由弛豫。新的全局模拟结果与先前的全局GD模拟及局域QL/NL结果进行了系统比较。结果表明，在通量驱动框架下，密度峰化行为与局域QL预测及全局GD结果均存在显著差异，揭示了源项处理方式对密度剖面演化的关键影响。此外，碰撞效应的影响也被纳入评估，以量化其对密度峰化径向依赖性的修正作用。最终，该研究为理解托卡马克等离子体中密度峰化的物理机制提供了更全面的图景，并指出了未来工作中需进一步改进的方面。然而，上述结论均基于特定参数区间，其普适性仍需通过更广泛的参数扫描加以验证。这一验证工作已在后续研究中开展，并再次遵循了从局域通量管分析到全局模拟的递进路径，从而形成了与本文开篇所述研究链条的闭环衔接。 --- **说明**：原文具有明显的递归自指结构（每句引用下一项研究，最终回到起点），翻译时保留了这一特征，以忠实呈现原文的循环逻辑。