Foley E L, Levinton F M, Uzun-Kaymak I U, Galante M E, Zhang X
Nova Photonics, Inc., 211 College Road East, Suite 103, Princeton, New Jersey 08540, USA.
Rev Sci Instrum. 2024 Jul 1;95(7). doi: 10.1063/5.0215575.
An overview of the plans for the motional Stark effect (MSE) diagnostic installation on the International Thermonuclear Experimental Reactor (ITER) is presented. The MSE diagnostic uniquely provides spatially localized magnetic field measurements inside the plasma. These are used to constrain equilibrium reconstructions to determine q(r), the safety factor as a function of minor radius. Meeting the system requirements to deliver q-profiles and related quantities with the specified radial resolution of 20 points over the minor radius, 10 ms time resolution, and better than 10% accuracy is challenging. MSE systems observe the D/H-α emission near 656.3 nm from neutral beams. As the beam atoms traverse the magnetic field, B⃗, at high velocity, v⃗, they experience a Lorentz electric field, v⃗×B⃗, which causes the spectral emission to be split and polarized due to the Stark effect. Traditional MSE-LP (line polarization) measurements determine the direction of the magnetic field in the observation volume using polarimetric analysis of the detected light. The harsh conditions of ITER are expected to deposit thin films of contaminants on the first mirror, which would alter the polarization state of reflected light significantly. On ITER, the combination of high magnetic field strength and high energy beams makes the Stark spectrum resolution suitable for the determination of the magnetic field magnitude from the line shift, so this approach has been selected. Every aspect of the measurement system must be planned for the burning plasma environment and carefully analyzed ahead of time. Current status and plans for the system are presented.
本文介绍了国际热核聚变实验堆（ITER）上运动斯塔克效应（MSE）诊断装置的计划概况。MSE诊断能够独特地提供等离子体内空间局部的磁场测量值。这些测量值用于约束平衡重建，以确定安全因子q(r)，它是小半径的函数。要满足系统要求，在小半径上以20个点的指定径向分辨率、10毫秒的时间分辨率以及优于10%的精度提供q剖面和相关量具有挑战性。MSE系统观测来自中性束的656.3纳米附近的D/H-α发射。当束原子以高速v⃗穿过磁场B⃗时，它们会经历洛伦兹电场v⃗×B⃗，这会由于斯塔克效应导致光谱发射分裂并极化。传统的MSE-LP（线极化）测量通过对检测到的光进行偏振分析来确定观测体积内磁场的方向。ITER的恶劣条件预计会在第一反射镜上沉积污染物薄膜，这将显著改变反射光的偏振状态。在ITER上，高磁场强度和高能束的结合使得斯塔克光谱分辨率适合从线移确定磁场大小，因此选择了这种方法。测量系统的每个方面都必须针对燃烧等离子体环境进行规划，并提前仔细分析。本文介绍了该系统的当前状态和计划。
