V. Quadri, P. Tamain, Y. Marandet, H. Bufferand, N. Rivals, G. Ciraolo, G. Falchetto, R. Düll, H. Yang
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引用次数: 0
Abstract
Experimental results from several tokamaks suggest a strong impact of divertor density regimes on turbulent transport in the edge plasma. Reciprocally, the change in transverse transport and SOL width affects the access to density regimes, making it a fundamental topic for heat exhaust issue. Such phenomenology is highly nonlinear and can only be approached quantitatively using numerical simulations treating turbulence and neutrals recycling physics self-consistently. In this study, the SOLEDGE3X edge multi-fluid code is used to investigate the mutual interaction between edge plasma turbulence and neutrals recycling. A fluid neutrals model based on the assumption of a charge-exchange-dominated plasma-neutral interaction has been implemented. Two simulations in circular geometry are compared: one without neutrals, where the particle flux is driven by a constant in flux from the core region, and the other one with neutrals recycling included in which the particle input to the system is self-consistently injected by a gas puff from the midplane. The presence of the neutrals triggers three types of perturbations on the plasma: a local and non-axisymmetric one driven by the gas puff, a global perturbation affecting both profiles and turbulence properties in the whole domain, and a local one in the vicinity of the limiter where recycling occurs. The largest effect of the inclusion of self-consistent neutrals recycling is a large-scale reorganization of the plasma profiles and turbulence properties due to the dissociation of particle and energy fluxes. These effects are expected to be more important at higher densities regimes or in diverted configuration.
几个托卡马克反应堆的实验结果表明,分流器密度制度对边缘等离子体的湍流输运有很大影响。反过来,横向传输和 SOL 宽度的变化也会影响到密度状态的进入,从而使其成为排热问题的一个基本主题。这种现象学是高度非线性的,只能通过自洽地处理湍流和中性回收物理的数值模拟来进行定量研究。本研究使用 SOLEDGE3X 边缘多流体代码来研究边缘等离子体湍流和中子回收之间的相互作用。基于电荷交换主导等离子体与中性相互作用的假设,实现了流体中性模型。比较了两种圆形几何模拟:一种不含中性粒子,粒子通量由来自核心区域的恒定通量驱动;另一种包含中性粒子循环,粒子输入系统的粒子由来自中平面的气体脉冲自洽注入。中性粒子的存在会对等离子体产生三种扰动:由气体脉冲驱动的局部非轴对称扰动、影响整个域的剖面和湍流特性的全局扰动,以及发生回收的限幅器附近的局部扰动。加入自洽中性再循环的最大影响是由于粒子和能量通量的解离而导致等离子体剖面和湍流特性的大规模重组。预计这些影响在密度较高的情况下或在分流配置中更为重要。