The Role of Plasma-Molecule Reactions in Influencing detachment.

热排放是未来聚变反应堆的一个关键问题，它需要通过分流器等离子体分离来缓解，其中分流器等离子体在通往分流器目标板的途中经历动量，功率和粒子通量的减少。长腿、强挡板导流器室加强等离子体中性相互作用（MAST-U、TCV、STEP、SPARC、ARC）并促进分离。在这种分流剂中，等离子体分子碰撞以及等离子体化学可以发挥重要作用。本研究通过分析mat - u和TCV的数据，并将其与简化模型和模拟进行比较，提出了等离子体分子动力学的新见解。这些机器上的高分辨率D2富尔彻波段测量（通过分流光谱学）允许获得分子的旋转振动分布，提供等离子体分子能量和动量传递和相互作用的信息。对mat - u (4000-9000 K)[3]和TCV （2000-5000 K）的旋转温度和两个器件（v = 0,1,2,3）的振动分布进行了详细的时间和空间分辨分析，表明旋转和振动分布之间存在联系。不同的导流器配置（master - u中的Super-X、细长型和常规型）；挡板（在TCV中有或没有筒仓挡板）；研究人员还研究了两个装置中不同的燃料位置和加热水平。我们发现，在转向器整体冷却之前，旋转温度在附着和分离状态下都有所升高。离子与分子弹性碰撞过程中能量传递的简化模型分子一生;和运输时间，都与这些发现一致。废气模拟结果也是一致的。这种在高中性压力下的弹性碰撞，加上这些较长的分子寿命，导致显著的能量和动量耗散——即加深分离。还对TCV进行了同位素研究。参考文献：b[1] K. Verhaegh等2021核。核聚变61 106014，[b] K. Verhaegh等[j]。核聚变63 016014[3]N. Osborne等2024等离子体物理。控制。聚变66 025008

Heat exhaust is a critical issue for future fusion reactors and it will need to be mitigated through divertor plasma detachment, in which the divertor plasma undergoes a reduction in momentum, power and particle flux en-route to the divertor target plates. Long-legged, strongly baffled divertor chambers intensify plasma-neutral interactions (MAST-U, TCV, STEP, SPARC, ARC) and facilitate detachment. In such divertors, plasma-molecular collisions, as well as plasma chemistry, can play an important role.This study presents a new insight into plasma-molecular kinetics through analysis of data from MAST-U and TCV, and comparison of this with simplified models, and simulations. High resolution D2 Fulcher band measurements (via divertor spectroscopy) on these machines allow the rovibrational distribution of the molecules to be obtained, providing information on plasma-molecule energy and momentum transfer and interactions. Detailed temporally and spatially resolved analyses of the rotational temperatures in MAST-U (4000-9000 K) [3] and TCV (2000-5000 K), and the vibrational distributions in both devices (v = 0, 1, 2, 3), show a connection between the rotational and vibrational distribution. Different divertor configurations (Super-X, Elongated and Conventional in MAST-U); baffling (with and without SILO baffles in TCV); and different fuelling locations and heating levels in both devices, have been studied. We find that rotational temperature increases during attached and detached conditions before the overall cooling of the divertor. A simplified model including energy transfer during elastic collisions between ions and molecules; molecule lifetime; and transport time, are consistent with these findings. Exhaust simulations are also consistent. Such elastic collisions in high neutral pressures, combined with these longer molecular lifetimes, lead to significant energy and momentum dissipation - i.e. deepening detachment. An isotopic study has also been carried out on TCV.References:[1] K. Verhaegh et al 2021 Nucl. Fusion 61 106014,[2] K. Verhaegh et al 2023 Nucl. Fusion 63 016014[3] N. Osborne et al 2024 Plasma Phys. Control. Fusion 66 025008