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arXiv 2511.03336physics.plasm-ph
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首次对ITER燃烧等离子体进行全局回旋动理学分布预测

First global gyrokinetic profile predictions of ITER burning plasma

A. Di Siena, C. Bourdelle, A. Bañón Navarro, G. Merlo, T. Görler, E. Fransson, A. Polevoi, S. H. Kim, F. Koechl, A. Loarte, E. Fable, C. Angioni, P. Mantica, F. Jenko

AI总结:

首次用GENE-Tango对15 MA ITER基准情景进行全局回旋动理学模拟,预测聚变增益Q=12.2,发现电磁模式主导芯部输运,安全因子分布对约束至关重要,带状流最终淬灭电子温度梯度湍流。

摘要:

在本研究中,我们首次使用GENE-Tango静电和电磁模拟,对在15 MA下运行的ITER基准情景进行了全局回旋动理学模拟。建模的径向区域从靠近磁轴处一直延伸到rho_tor = 0.6。我们的结果显示出明显的密度峰化,该峰化由电磁涨落所调节。该情景预测的聚变增益为Q = 12.2,与ITER的任务目标高度一致。我们进一步表征了湍流谱,发现电磁模式(如微撕裂模、动理学气球模以及低双正交波数下的Alfven离子温度梯度模)在该ITER情景的芯部输运中起着关键作用,这需要高数值分辨率才能进行准确建模。局部磁通管模拟在定性上重现了全局回旋动理学模拟中观察到的关键特征,但对分布梯度表现出高得多的敏感性,反映出刚度增加,这可能是由于平衡分布和安全因子的线性化所致。我们的研究还表明,施加的外部环向旋转分布对湍流输运的影响可以忽略不计,因为其量级远低于主导的线性增长率。此外,我们证明安全因子分布至关重要:具有近零磁剪切平坦q分布的情景会导致等离子体芯部动理学气球模失稳,显著增强湍流输运并可能降低约束。最后,尽管电子温度梯度湍流最初显得很大,有时甚至超过离子尺度输运水平,但它最终在长时间尺度上被带状流的长期演化所淬灭,这些带状流在ITER预期的极低碰撞率条件下仅受到微弱阻尼。

英文摘要:

In this work, we present the first global gyrokinetic simulations of the ITER baseline scenario operating at 15 MA using GENE-Tango electrostatic and electromagnetic simulations. The modeled radial region spans close to the magnetic axis up to rho_tor = 0.6. Our results show a pronounced density peaking, moderated by electromagnetic fluctuations. The predicted fusion gain for this scenario is Q = 12.2, aligning well with ITER's mission objectives. We further characterize the turbulence spectra and find that electromagnetic modes, such as microtearing modes, kinetic ballooning modes, and Alfvenic ion temperature gradient modes at low binormal wave numbers, play a critical role in the core transport of this ITER scenario, necessitating high numerical resolution for accurate modeling. Local flux-tube simulations qualitatively reproduce the key features observed in the global gyrokinetic simulations but exhibit a much higher sensitivity to profile gradients, reflecting increased stiffness, likely due to the linearization of the equilibrium profiles and safety factor. Our study also reveals that the imposed external toroidal rotation profiles have a negligible impact on turbulent transport, as their magnitudes are substantially lower than the dominant linear growth rates. Furthermore, we demonstrate that the safety factor profile is of paramount importance: scenarios featuring flat q profiles with near-zero magnetic shear lead to the destabilization of kinetic ballooning modes in the plasma core, significantly enhancing turbulent transport and potentially degrading confinement. Finally, although electron temperature gradient turbulence initially appears large, sometimes exceeding ion-scale transport levels, it is ultimately quenched over long timescales by secular evolution of zonal flows, which are weakly damped under the very low collisionality conditions expected in ITER.

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