Colgan C, Bohlin H, Buxton P F, Harryman D M, Jones O, Lowe H F, Naylor G, O'Gorman T, Pyragius T, Sertoli M, Sladkomedova A, Sridhar S, Thwaites R
Tokamak Energy Ltd, Abingdon OX14 4SD, United Kingdom.
Rev Sci Instrum. 2024 Oct 1;95(10). doi: 10.1063/5.0218723.
As part of its roadmap to developing commercial fusion plants, Tokamak Energy Ltd. operates the high field spherical tokamak ST40. Studies on this device will help to expand the high field spherical tokamak physics basis by characterizing confinement and the fusion triple product. In support of this, bolometers and broadband and x-ray sensitive diodes can provide information on key energy loss mechanisms of the plasma. These mechanisms include core magnetohydrodynamic activity that deteriorates confinement, such as sawtooth crashes that can be used to characterize relaxations in the q-profile. In addition, combinations of these diagnostics can be used to infer the total radiated power losses and plasma composition. Here, we present results from a new, midplane, tangential, Be-filtered diode with 16 channels spanning the radial extent of the plasma. The system is shown to resolve magnetohydrodynamic instabilities (up to 100 kHz) and be able to provide radiation profiles through tomography. The tomographic inversion routine is compared against other diagnostics on ST40 and provides emissivity measurements across a variety of operating scenarios. Finally, we look ahead to implementing multiple soft x-ray cameras on ST40 and the improvements this will have on the diagnostic capabilities.
作为其开发商用聚变装置路线图的一部分，托卡马克能源有限公司运营着高场球形托卡马克ST40。对该装置的研究将有助于通过表征约束和聚变三重积来扩展高场球形托卡马克的物理基础。为此，测热辐射计以及宽带和X射线敏感二极管可提供有关等离子体关键能量损失机制的信息。这些机制包括会使约束恶化的核心磁流体动力学活动，例如可用于表征q轮廓弛豫的锯齿崩溃。此外，这些诊断方法的组合可用于推断总辐射功率损失和等离子体成分。在此，我们展示了一种新的位于中平面、切向、带有铍滤光片的16通道二极管的结果，该二极管跨越了等离子体的径向范围。该系统被证明能够分辨磁流体动力学不稳定性（高达100 kHz），并能够通过层析成像提供辐射分布。将层析反演程序与ST40上的其他诊断方法进行了比较，并在各种运行场景下提供了发射率测量结果。最后，我们展望在ST40上安装多个软X射线相机以及这将对诊断能力带来的提升。
