Abstract This paper presents the development of a coupled shape and divertor controller for ITER with capabilities to control the flux expansion and an advanced divertor configuration, the x-divertor (XD), in which a secondary x-point is placed in the downstream scrape-off layer. Due to the high-performance nature of ITER and its relatively few shaping coils, satisfying constraints on the coil currents, power supplies, and plasma shape is a challenge for this configuration. To meet these constraints the controller uses the constrained linear quadratic regulator (CLQR) framework [1] , a variant of model predictive control (MPC). Previous work [2] has shown the existence of XD equilibria on ITER and in this study, we identify a control pathway for achieving the “pure” XD where the secondary x-point is placed at the outer strike point, representing a maximally flux-expanding scenario. Constraints are observed throughout the transition. One limitation is that at high flux expansion, the shallow angle of incidence of the magnetic field on the divertor results in a reduced plasma wetted area via tile shadowing. On the other hand, the high flux expansion and flaring characteristic of the XD facilitate enhanced detachment, which could negate the shadowing effect to some degree. In this case it would be desirable to operate as close to the flux expansion limit as possible. To this end we also demonstrate the controller's ability to track a trajectory for the flux expansion near the accepted angle of incidence limit.

中文翻译：

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ITER 先进偏滤器的控制路径

摘要 本文介绍了用于 ITER 的耦合形状和偏滤器控制器的开发，该控制器具有控制通量膨胀的能力和先进的偏滤器配置，即 x 偏转器 (XD)，其中第二个 x 点位于下游刮板中。离层。由于 ITER 的高性能特性及其相对较少的整形线圈，满足对线圈电流、电源和等离子体形状的限制对于这种配置是一个挑战。为了满足这些约束，控制器使用了约束线性二次调节器 (CLQR) 框架 [1]，这是模型预测控制 (MPC) 的一种变体。先前的工作 [2] 已经表明 ITER 上存在 XD 平衡，在本研究中，我们确定了实现“纯”XD 的控制途径，其中次级 x 点位于外部撞击点，表示最大通量扩展方案。在整个转换过程中都会观察到约束。一个限制是在高通量扩展时，偏滤器上磁场的小入射角会导致通过瓷砖阴影减少等离子体润湿面积。另一方面，XD 的高通量膨胀和扩口特性有利于增强分离，这可以在一定程度上抵消阴影效应。在这种情况下，最好在尽可能接近通量扩展极限的情况下运行。为此，我们还展示了控制器在可接受的入射角极限附近跟踪通量扩展轨迹的能力。偏滤器上磁场的小入射角通过瓷砖阴影减少了等离子体润湿面积。另一方面，XD 的高通量膨胀和扩口特性有利于增强分离，这可以在一定程度上抵消阴影效应。在这种情况下，最好在尽可能接近通量扩展极限的情况下运行。为此，我们还展示了控制器在可接受的入射角极限附近跟踪通量扩展轨迹的能力。偏滤器上磁场的小入射角通过瓷砖阴影减少了等离子体润湿面积。另一方面，XD 的高通量膨胀和扩口特性有利于增强分离，这可以在一定程度上抵消阴影效应。在这种情况下，最好在尽可能接近通量扩展极限的情况下运行。为此，我们还展示了控制器在可接受的入射角极限附近跟踪通量扩展轨迹的能力。在这种情况下，最好在尽可能接近通量扩展极限的情况下运行。为此，我们还展示了控制器在可接受的入射角极限附近跟踪通量扩展轨迹的能力。在这种情况下，最好在尽可能接近通量扩展极限的情况下运行。为此，我们还展示了控制器在可接受的入射角极限附近跟踪通量扩展轨迹的能力。