Investigation on FTU dust and on the origin of ferromagnetic and lithiated grains
Investigation on FTU dust and on the origin of ferromagnetic and lithiated grains
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DOI：
10.1088/0029-5515/55/12/123005
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发表时间：
2015-10
期刊：
影响因子：
3.3
通讯作者：
M. De Angeli;L. Laguardia;G. Maddaluno;E. Perelli Cippo;D. Ripamonti;M. Apicella;C. Bressan;R. Caniello;C. Conti;F. Ghezzi;G. Grosso;G. Mazzitelli
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文献类型：
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作者：
M. De Angeli;L. Laguardia;G. Maddaluno;E. Perelli Cippo;D. Ripamonti;M. Apicella;C. Bressan;R. Caniello;C. Conti;F. Ghezzi;G. Grosso;G. Mazzitelli
对2013年关停期间FTU中收集的金属微粒的成分和形态进行了全面分析。所分析的数据集是FTU多年实验活动的结果，FTU是一台自开始运行以来的全金属机器，并从2005年开始配备液态锂限制器（LLL）。发现由来自面向等离子体的组分（主要是SS和Mo）的薄片、粉碎的和球形的颗粒组成的金属群体表现出出乎意料的高（高达70重量%）的磁性颗粒分数。不锈钢颗粒中的铁成分由γ晶相转变为α/δ晶相是产生磁粉的机理。这种相变可以归因于颗粒温度淬火和/或在熔融不锈钢液滴的再凝固期间存在强磁场。在连接到收集的灰尘接近LLL，主要由碳酸锂球状颗粒可达几毫米，Li 2CO 3的形成和它的作用作为C和O杂质的来源的机制进行了讨论。
A comprehensive analysis of composition and morphology of metallic micrometric particles collected in FTU during the 2013 shut-down is presented. The data-set analyzed is the result of years of experimental activity in FTU which is a full metal machine since the beginning of operation and with a liquid lithium limiter (LLL) from 2005. It was found that the metallic population, consisting of flakes, smashed and spheroidally shaped particles from plasma facing components (mainly SS and Mo), exhibits an unexpectedly high, up to 70 wt%, fraction of magnetic grains. The change of crystalline phase from γ to α/δ of the iron component contained in the particles coming from stainless steel is suggested as the mechanism responsible for magnetic dust production. This phase change can be ascribed to the particle temperature quench and/or to the presence of a strong magnetic field during the re-solidification of molten stainless steel droplets. In connection to the dust collected close to the LLL, consisting mainly of lithium carbonate spherical-like particles up to a few mm, the mechanism of Li2CO3 formation and its role as a source of C and O impurities are discussed.