Title: Effects of flux-surface impurity density variation on collisional transport in stellarators Show Chinese title

Title: 通量面杂质密度变化对星环器中碰撞输运的影响

Abstract: High-Z impurities in magnetic confinement devices are prone to develop density variations on the flux-surface, which can significantly affect their transport. In this paper, we generalize earlier analytic stellarator calculations of the neoclassical radial impurity flux in the mixed-collisionality regime (collisional impurity and low-collisionality bulk ions) to include the effect of such flux-surface variations. We find that only in the homogeneous density case is the transport of highly collisional impurities (in the Pfirsch-Schl\"{u}ter regime) independent of the radial electric field. We study these effects for a Wendelstein 7-X (W7-X) vacuum field, with simple analytic models for the potential perturbation, under the assumption that the impurity density is given by a Boltzmann response to a perturbed potential. In the W7-X case studied, we find that larger amplitude potential perturbations cause the radial electric field to dominate the transport of the impurities. In addition, we find that classical impurity transport can be larger than the neoclassical transport in W7-X. Show Chinese abstract

Abstract: 高Z杂质在磁约束装置中容易在磁通面上产生密度变化，这可能会显著影响它们的输运。 在本文中，我们将先前关于混合碰撞率区域（碰撞性杂质和低碰撞率主体离子）中经典径向杂质通量的解析扭摆器计算进行推广，以包括这种磁通面变化的影响。 我们发现，只有在密度均匀的情况下，高碰撞率杂质（在Pfirsch-Schlüter区域）的输运才与径向电场无关。 我们研究了Wendelstein 7-X（W7-X）真空场的情况，在假设杂质密度由扰动势的玻尔兹曼响应给出的前提下，使用简单的解析模型来描述势扰动。 在所研究的W7-X情况下，我们发现振幅较大的势扰动会导致径向电场主导杂质的输运。 此外，我们发现W7-X中的经典杂质输运可能大于经典输运。