Experimental study on the role of the target electron temperature as a key parameter linking recycling to plasma performance in JET-ILW
Experimental study on the role of the target electron temperature as a key parameter linking recycling to plasma performance in JET-ILW
复制标题
JET-ILW 中目标电子温度作为连接回收与等离子体性能的关键参数的实验研究
DOI：
10.1088/1741-4326/ac5668
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发表时间：
2022
期刊：
影响因子：
3.3
通讯作者：
Jet Contributors
中科院分区：
文献类型：
--
作者：
B. Lomanowski;M. Dunne;N. Vianello;S. Aleiferis;M. Brix;J. Canik;I. Carvalho;L. Frassinetti;D. Frigione;L. Garzotti;M. Groth;A. Meigs;S. Menmuir;M. Maslov;T. Pereira;C. Perez von Thun;M. Reinke;D. Réfy;F. Rimini;G. Rubino;P. Schneider;G. Sergienko;A. Uccello;D. van Eester;Jet Contributors
全球和边缘等离子体参数（h98 (y,2)，无因次碰撞ν *，核心密度峰值，分离矩阵密度n e，sep）的变化与D2燃料速率和分流器配置的变化在映射到⟨T e，ot⟩（空间平均光谱衍生的外部目标电子温度）时统一为单一趋势。专用JET与iter样壁（JET- ilw）实验结合非种子低三角形h模式等离子体的扩展JET- ilw数据库，跨越广泛的D2加油速率，I p， B t和加热功率，已经证明⟨te，ot⟩作为将回收粒子源和分离与等离子体性能联系起来的关键物理参数的重要性。⟨T e，ot⟩的非常强健的h98 （y,2）趋势与⟨T e，ot⟩，ne，sep和ν *之间的强烈逆相关相连，从而将⟨T e，ot⟩缓和的分流器再循环的变化与先前建立的ν *，核密度峰值和核压力之间的关系直接联系起来，导致核等离子体性能随着⟨T e，ot⟩的减少（ν *的增加）而退化。分离矩阵到基座密度比，n e,sep/n e,ped，和⟨T e，ot⟩之间也建立了一个很强的逆相关，随着n e，sep/n e，ped的上升在⟨T e，ot⟩bbb10 eV处饱和。观察到h98 （y,2）的强烈减少，因为⟨T e，ot⟩通过额外的D2气体燃料从30 eV驱动到10 eV，而分流器仍然连接。因此，在附加导流器条件下，明显的性能下降意味着杂质播种辐射导流器的情况，在杂质注入等离子体之前，h98 （y,2）已经很低（~ 0.7），因为需要适度的气体加注速率来提高导流器的中性压。还观察到有利的基座压力，pe,ped，依赖于I p，pe的总体增加，p p = 3.4 MA，因为⟨T e，ot⟩从附着到高循环的分流器条件下被驱动下来。相反，pe，ped在较低的I p分支中随着⟨T e，ot⟩的减少而减少。需要进一步的工作来(i)澄清边缘不透明度对观察到的有利基座压力i p缩放的潜在作用；以及（ii）用⟨T e，ot⟩将全球和边缘等离子体性能趋势预测到反应堆规模的设备，以提高在预计更不透明的边缘等离子体条件下回收和受限等离子体燃料之间耦合的预测能力。
Changes in global and edge plasma parameters (H 98(y,2), dimensionless collisionality ν *, core density peaking, separatrix density n e,sep) with variations in the D2 fueling rate and divertor configuration are unified into a single trend when mapped to ⟨T e,ot⟩, the spatially averaged spectroscopically derived outer target electron temperature. Dedicated JET with the ITER-like wall (JET-ILW) experiments in combination with an extended JET-ILW database of unseeded low-triangularity H-mode plasmas spanning a wide range of D2 fueling rates, I p, B t and heating power have demonstrated the importance of ⟨T e,ot⟩ as a key physics parameter linking the recycling particle source and detachment with plasma performance. The remarkably robust H 98(y,2) trend with ⟨T e,ot⟩ is connected to a strong inverse correlation between ⟨T e,ot⟩, n e,sep and ν *, thus directly linking changes in the divertor recycling moderated by ⟨T e,ot⟩ with the previously established relationship between ν *, core density peaking and core pressure resulting in a degradation in core plasma performance with decreasing ⟨T e,ot⟩ (increasing ν *). A strong inverse correlation between the separatrix to pedestal density ratio, n e,sep/n e,ped, and ⟨T e,ot⟩ is also established, with the rise in n e,sep/n e,ped saturating at ⟨T e,ot⟩ > 10 eV. A strong reduction in H 98(y,2) is observed as ⟨T e,ot⟩ is driven from 30 to 10 eV via additional D2 gas fueling, while the divertor remains attached. Consequently, the pronounced performance degradation in attached divertor conditions has implications for impurity seeding radiative divertor scenarios, in which H 98(y,2) is already low (∼0.7) before impurities are injected into the plasma since moderate gas fueling rates are required to promote high divertor neutral pressure. A favorable pedestal pressure, p e,ped, dependence on I p has also been observed, with an overall increase in p e,ped at I p = 3.4 MA as ⟨T e,ot⟩ is driven down from attached to high-recycling divertor conditions. In contrast, p e,ped is reduced with decreasing ⟨T e,ot⟩ in the lower I p branches. Further work is needed to (i) clarify the potential role of edge opacity on the observed favorable pedestal pressure I p scaling; as well as to (ii) project the global and edge plasma performance trends with ⟨T e,ot⟩ to reactor-scale devices to improve predictive capability of the coupling between recycling and confined plasma fueling in what are foreseen to be more opaque edge plasma conditions.