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arXiv 2307.05085physics.plasm-ph
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HL-2A托卡马克等离子体中内部输运垒形成的自维持机制

A self-sustaining mechanism for Internal Transport Barrier formation in HL-2A tokamak plasmas

W. H. Lin, J. Garcia, J. Q. Li, S. Mazzi, Z. J. Li, X. X. He, X. Yu

AI总结:

本文通过非线性回旋动理学模拟研究HL-2A中内部输运垒的形成,提出分阶段机制:早期快离子稀释效应触发ITB,后期由ITB失稳的高频电磁扰动与带状流非线性耦合实现自维持。

摘要:

通过非线性回旋动理学模拟研究了HL-2A等离子体中内部输运垒(ITB)的形成。提出了一种ITB形成的新范式,其中不同的物理机制在ITB形成的不同阶段发挥不同作用。在早期阶段,由中性束注入(NBI)离子系统引入的快离子被发现通过稀释效应稳定热离子驱动的不稳定性,从而降低离子热通量并最终触发ITB。然而,在ITB触发后,这种稀释效应只起次要作用,因为在已建立的高压强梯度存在的情况下,电磁效应占主导地位。我们定义了ITB自维持的概念,即在完全形成的ITB内部发现的低湍流水平是大尺度带状流的结果,而这些带状流又通过与ITB自身失稳的大尺度高频电磁扰动之间的非线性相互作用得到能量供给。

英文摘要:

The formation of Internal Transport Barrier (ITB) is studied in HL-2A plasmas by means of nonlinear gyrokinetic simulations. A new paradigm for the ITB formation is proposed in which different physics mechanisms play a different role depending on the ITB formation stage. In the early stage, fast ions, introduced by Neutral Beam Injection (NBI) ion system, are found to stabilize the thermal-ion-driven instability by dilution, thus reducing the ion heat fluxes and finally triggering the ITB. Such dilution effects, however, play a minor role after the ITB is triggered as electromagnetic effects are dominant in the presence of established high pressure gradients. We define the concept of ITB self-sustainment, as the low turbulence levels found within the fully formed ITB are consequences of large scale zonal flows, which in turn are fed by a non-linear interplay with large scale high frequency electromagnetic perturbations destabilized by the ITB itself.

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