York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom.
Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Rev Sci Instrum. 2023 Mar 1;94(3):033502. doi: 10.1063/5.0128768.
A prototype infrared video bolometer (IRVB) was successfully deployed in the Mega Ampere Spherical Tokamak Upgrade (MAST Upgrade or MAST-U), the first deployment of such a diagnostic in a spherical tokamak. The IRVB was designed to study the radiation around the lower x-point, another first in tokamaks, and has the potential to estimate emissivity profiles with spatial resolution beyond what is achievable with resistive bolometry. The system was fully characterized prior to installation on MAST-U, and the results are summarized here. After installation, it was verified that the actual measurement geometry in the tokamak qualitatively matches the design; this is a particularly difficult process for bolometers and was done using specific features of the plasma itself. The installed IRVB measurements are consistent both with observations from other diagnostics, including magnetic reconstruction, visible light cameras, and resistive bolometry, as well as with the IRVB-designed view. Early results show that with conventional divertor geometry and only intrinsic impurities (for example, C and He), the progression of radiative detachment follows a similar path to that observed for large aspect ratio tokamaks: The peak of the radiation moves along the separatrix from the targets to the x-point and high-field side midplane with a toroidally symmetric structure that can eventually lead to strong effects on the core plasma inside the separatrix.
成功在大型螺旋装置升级（MAST Upgrade 或 MAST-U）中部署了原型红外视频测辐射热仪（IRVB），这是此类诊断首次在球形托卡马克中部署。IRVB 的设计目的是研究下部 X 点周围的辐射，这在托卡马克中也是首次，它有可能估计发射率分布，其空间分辨率超出电阻测辐射热仪的能力。在安装到 MAST-U 之前，对系统进行了全面的特性描述，这里总结了结果。安装后，验证了在托卡马克中实际测量几何形状与设计定性匹配；这对于测辐射热仪来说是一个特别困难的过程，是使用等离子体本身的特定特征完成的。安装的 IRVB 测量结果与其他诊断的观察结果一致，包括磁场重建、可见光相机和电阻测辐射热仪，以及与 IRVB 设计视图一致。早期结果表明，在传统的偏滤器几何形状和仅固有杂质（例如 C 和 He）的情况下，辐射分离的进展遵循与大纵横比托卡马克类似的路径：辐射的峰值从靶标沿分隔器沿分隔器移动到 X 点和高场侧中间平面，具有轴对称结构，最终可能对分隔器内的核心等离子体产生强烈影响。
