Outline of optical design and viewing geometry for divertor Thomson scattering on MAST upgrade
Outline of optical design and viewing geometry for divertor Thomson scattering on MAST upgrade
复制标题
MAST 升级中偏滤器汤姆森散射的光学设计和观察几何结构概述
DOI：
--
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
P. Bohm
中科院分区：
文献类型：
--
作者：
J. Hawke;R. Scannell;J. Harrison;R. Huxford;P. Bohm
MAST升级中的超X偏滤器将通过汤姆逊散射诊断进行诊断。本文讨论了收集光学系统的初步设计和诊断性能的计算。作为设计的一部分，对收集室的位置和尺寸进行了优化，以尽量减少渐晕，特别是在靠近偏滤器撞击点的感兴趣区域。由于封闭偏滤器几何结构中可利用的通道有限，使设计过程复杂化。在诊断性能的研究中，研究了径向分辨率、激光图像在光纤束上的投影以及多激光系统的景深影响。在该设计中，在系统的分辨率和束流收集器的寿命之间存在折衷。由于这个原因，光束的焦点在观察区的开始处，并且在偏滤器瓦片附近在宽度上发散到大约5毫米。光束宽度的这种大的变化的影响，主要是在两个极端的光线跟踪建模。该模型将具有光束宽度尺寸的物体成像到光纤束上，以研究窄或宽激光图像的未对准影响。以类似的方式进行光线跟踪，以确定四个和两个激光系统的景深的影响。由于系统的电子密度可能较低，性能分析考虑同时发射多个激光器以改善光子统计。
The super-X divertor on MAST Upgrade will be diagnosed by a Thomson scattering diagnostic. A preliminary design of the collection optics and calculations of the diagnostic's performance are discussed in this paper. As part of the design the location and size of the collection cell were optimized to minimize vignetting, especially in the region of interest close to the divertor strike point. The design process was complicated by the limited access available in the closed divertor geometry. In the study of the diagnostic's performance, the radial resolution, projection of the laser image onto the fiber bundle, and impact of depth of field with a multiple laser system were investigated. In this design there is a trade-off between the resolution of the system and the lifetime of the beam dump. For this reason the beam has its focal point at the start of the viewing region and diverges in width to approximately five millimeters near the divertor tile. The effect of this large variation in beam width is examined primarily at the two extremes by means of ray trace modeling. This model takes an object with dimensions of the beam width imaged onto the fiber bundle to investigate the effect of misalignment for a narrow or broad laser image. In a similar manner ray tracing was performed to determine the effects of depth of field for four and two laser systems. As the electron density of the system may be low, performance analysis considers firing multiple lasers simultaneously to improve photon statistics.