Ochoukov R, Bobkov V, Faugel H, Fünfgelder H, Jacquot J, Noterdaeme J-M, Suárez López G
Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
Rev Sci Instrum. 2016 Nov;87(11):11D301. doi: 10.1063/1.4960148.
A new array of B-dot probes was installed on ASDEX Upgrade. The purpose of the new diagnostic is to study Ion Cyclotron Range-off Frequencies (ICRF) wave field distributions in the evanescent scrape-off layer (SOL) plasma region on the low field side of ASDEX Upgrade. The vacuum measurements (no gas, B = 0 T) reveal ICRF wave field measurements consistent with the profiles expected from the newly installed 3-strap ICRF antennas outside the antenna box: the shape of the toroidal distribution of both the amplitude and the phase is the same for the case of only the central straps being active, as for the case of only the side straps being active. These profiles become strongly modified during plasma operations. The modifications can be separated into two types: "Inter-edge localized mode (ELM)" and "During-ELM" periods. The phase distribution of the ICRF wave fields remains well-defined during the Inter-ELM period; however, it becomes more spread out over the entire 360° range during ELMs. The observed modulations cannot be explained by the observed changes in the ICRF power, as monitored in the transmission line. However, they are consistent with ICRF coupling changes introduced by plasma filaments: the plasma density perturbations due to the filaments are high enough to change the nature of the fast ICRF wave field from evanescent to propagating. The coverage of the present diagnostic is being expanded to include both the low field side and the high field side probes. Additionally, a manipulator probe head is being developed to measure ICRF wave field radial profiles across the SOL region.
一个新的B-dot探针阵列安装在了ASDEX升级装置上。这个新诊断设备的目的是研究ASDEX升级装置低场侧消逝刮离层（SOL）等离子体区域中的离子回旋频率范围（ICRF）波场分布。真空测量（无气体，B = 0 T）显示ICRF波场测量结果与天线箱外新安装的三带ICRF天线预期的轮廓一致：仅中央带激活的情况下和仅侧边带激活的情况下，幅度和相位的环形分布形状相同。这些轮廓在等离子体运行期间会发生显著变化。这些变化可分为两种类型：“边缘局域模（ELM）间”和“ELM期间”。在ELM间期间，ICRF波场的相位分布保持清晰；然而，在ELM期间，它在整个360°范围内变得更加分散。如传输线中监测到的，观察到的调制不能用ICRF功率的变化来解释。然而，它们与等离子体细丝引起的ICRF耦合变化一致：细丝引起的等离子体密度扰动足够高，足以将快速ICRF波场的性质从消逝变为传播。目前诊断设备的覆盖范围正在扩大，以包括低场侧和高场侧的探针。此外，正在开发一种操纵器探头，以测量整个SOL区域的ICRF波场径向轮廓。
