An in situ accelerator-based diagnostic for plasma-material interactions science on magnetic fusion devices.
An in situ accelerator-based diagnostic for plasma-material interactions science on magnetic fusion devices.
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DOI：
10.1063/1.4832420
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发表时间：
2013-12
期刊：
影响因子：
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通讯作者：
Z. Hartwig;H. Barnard;R. Lanza;B. Sorbom;P. Stahle;D. Whyte
中科院分区：
文献类型：
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作者：
Z. Hartwig;H. Barnard;R. Lanza;B. Sorbom;P. Stahle;D. Whyte
本文提出了一种新的粒子加速器为基础的诊断，非破坏性测量磁聚变装置内的材料表面成分的演变。诊断的目的是有助于磁融合中的等离子体-材料相互作用的综合理解，这是严重阻碍了缺乏原位材料表面诊断。诊断的目的是远程生成同位素浓度地图上的等离子体拍摄到拍摄的时间尺度，覆盖大部分的磁聚变装置内的等离子体面对表面，而不需要真空中断或物理访问的材料表面。我们的仪器使用一个紧凑的（~1米），高电流（~1毫安）的射频四极加速器注入0.9兆电子伏的氘核到Alcator C-Mod托卡马克在麻省理工学院。我们控制托卡马克磁场-在等离子体发射之间-将氘核引导到材料表面，在那里氘核引起高Q核反应，低Z同位素进入材料约5 μm。用闪烁探测器测量感应的中子和伽马射线;能谱分析提供表面成分的定量重建。诊断技术的概述，被称为加速器为基础的原位材料监测（AIMS），和第一AIMS诊断的AlcatorC-Mod托卡马克。实验验证表明，一个优化的氘束注入托卡马克，低Z同位素，如氘和硼，可以量化的材料表面上，磁转向提供访问不同的测量位置。还介绍了第一次AIMS分析，该分析测量了Alcator C-Mod FY 2012等离子体活动结束时单个表面位置处氘的相对变化。
This paper presents a novel particle accelerator-based diagnostic that nondestructively measures the evolution of material surface compositions inside magnetic fusion devices. The diagnostic's purpose is to contribute to an integrated understanding of plasma-material interactions in magnetic fusion, which is severely hindered by a dearth of in situ material surface diagnosis. The diagnostic aims to remotely generate isotopic concentration maps on a plasma shot-to-shot timescale that cover a large fraction of the plasma-facing surface inside of a magnetic fusion device without the need for vacuum breaks or physical access to the material surfaces. Our instrument uses a compact (~1 m), high-current (~1 milliamp) radio-frequency quadrupole accelerator to inject 0.9 MeV deuterons into the Alcator C-Mod tokamak at MIT. We control the tokamak magnetic fields--in between plasma shots--to steer the deuterons to material surfaces where the deuterons cause high-Q nuclear reactions with low-Z isotopes ~5 μm into the material. The induced neutrons and gamma rays are measured with scintillation detectors; energy spectra analysis provides quantitative reconstruction of surface compositions. An overview of the diagnostic technique, known as accelerator-based in situ materials surveillance (AIMS), and the first AIMS diagnostic on the Alcator C-Mod tokamak is given. Experimental validation is shown to demonstrate that an optimized deuteron beam is injected into the tokamak, that low-Z isotopes such as deuterium and boron can be quantified on the material surfaces, and that magnetic steering provides access to different measurement locations. The first AIMS analysis, which measures the relative change in deuterium at a single surface location at the end of the Alcator C-Mod FY2012 plasma campaign, is also presented.