聚变装置面对等离子体材料激光诱导击穿光谱原位诊断技术研究

发布时间：2018-05-16 00:17

  本文选题：激光诱导击穿光谱 + 聚变等离子体装置　； 参考：《大连理工大学》2015年博士论文

【摘要】：在托卡马克运行过程中,面对等离子体材料(Plasma-Facing Material, PFM)会受到来自芯部等离子体的稳态/瞬态热流和粒子流的冲击,发生一系列等离子体与壁材料相互作用(Plasma Wall Interaction, PWI)过程,导致燃料滞留、杂质产生、起泡、共沉积等问题。而能否解决这些问题,是决定未来ITER (International Thermonuclear Experimental Reactor)计划成功与否最为关键的因素之一。直线等离子体装置可以产生具有托卡马克边缘等离子体参数的稳态/瞬态等离子体束流,用其产生的等离子体束轰击PFM样品,可以模拟研究托卡马克PWI过程,是进行PWI模拟实验研究的主要途径。然而受到诊断手段的制约,PWI的原位诊断研究具有相当大的挑战。因此,发展PFM元素成分原位诊断技术用于直线等离子体装置以及托卡马克装置是急需解决的关键问题之一。PFM表面的元素成分的实时原位的获得,对理解PWI过程、揭示PWI机理、提出PFM优化方案具有非常重要的意义。针对上述问题,本论文发展了激光诱导击穿光谱(Laser-Induced Breakdown Spectroscopy, LIB S)原位壁诊断技术,用于直线等离子体装置Magnum-PSI、 DUT-PSI以及托卡马克聚变装置EAST(Experimental Advanced Superconducting Tokamak)中PFM样品元素成分的原位诊断,并研究了PWI过程中的燃料滞留、杂质产生、锂化共沉积等关键科学问题。具体内容如下：在第二章中,介绍了在Magnum-PS I直线等离子体装置上建立的LIBS原位PFM诊断系统,可在10-7 mbar背景气压下,获得PFM元素高时空分辨LIBS光谱信号。该套LIBS系统的成功建立是国际上首次将LIBS用于大型直线等离子体实验装置。利用Magnum-PSI装置产生的高通量氘等离子体(1024 m-2s-1),结合原位LIBS 技术,研究了不同剂量氘等离子体辐照后的纯钨、锂化钨、原始石墨瓦、锂化石墨瓦的氘滞留和元素分布性质,发现锂对钨表面起泡具有明显的抑制作用。实验表明,在1.9 1025m-2剂量的氘等离子体辐照下,锂化钨中氘的信号强度明显高于纯钨材料中氘的信号强度,这主要是由锂与氘的化学反应导致的强烈的化学吸附造成的；随着氘等离子体辐照剂量增加至6.210 25 m-2,纯钨和锂化钨的样品都出现明显的氘滞留饱和现象。LIBS深度分析结果表明,锂、氘、氢信号随深度的增加而降低,钨信号随深度先加强后达到稳定值；氘等离子体辐照可使锂再沉积过程与溅射过程达到平衡。X射线光电子能谱(X-ray Photoelectron Spectroscopy, XPS)离线分析结果表明,LIBS与XPS获得的各元素的分布结果一致。通过对锂化钨样品的LIBS激光烧蚀坑的分析,发现激光烧蚀后,氘等离子体辐照使锂发生了显著的再沉积现象。在第三章中,介绍了低气压直流级联弧等离子体束装置(DUT-PSI)的建立；利用发射光谱二维等离子体参数诊断系统,对氩/氮激波状态等离子体束激波区的发光强度、电子温度、振动温度和转动温度同时进行了测量。结果表明,在激波状态等离子体的压缩区,等离子体发光强度较高、电子温度较低、振动温度和转动温度较高。各温度具有明显的差异,说明低气压等离子体束处于显著的非平衡状态。经过对DUT-PSI电极结构优化升级后,该装置可产生具有类偏滤器区域等离子体参数的低温高密度等离子体束,电子温度为1-1.2 eV、电子密度可达210 14 cm-3,可用于模拟研究钨的锂化等PWI相关过程。结合原位LIBS元素化学成像系统,研究了锂化钨材料及其杂质元素在样品表面三维分布特性。研究表明锂化钨样品表面的锂、氢、氧和氩元素分布具有相似的趋势,在锂信号强度高的区域,氢、氧、氩元素的信号强度也高,但与其它元素如钨的分布不同。通过离线XPS能谱分析,佐证了LIBS化学成像的分析结果,并对激光烧蚀区、锂化钨表面等不同位置的元素化学态进行了分析。在第四章中,通过对2012年EAST实验周期的偏滤器石墨瓦(该瓦共经历了5621次放电,总放电时间超过50000 s)进行离线LIBS分析,发现氘在EAST偏滤器石墨瓦上的滞留主要是通过锂-氘共沉积层引起的。氘的滞留比例(D/(D+H))随着深度先增加,随后稳定在0.17左右,该值可以反映出EAST放电时在该偏滤器瓦处的氘滞留比例。针对EAST内的低气压真空环境,研究了LIBS等离子体收集区域对LIBS信号采集的影响。对碳、硅、钼等常见PFM样品元素进行空间分辨LIBS分析,发现由于脉冲激光烧蚀等离子体的轫致辐射、复合以及真空环境下等离子体超声膨胀过程,碳、硅、钼的信号强度从激光烧蚀等离子体的中心到边缘先升高后下降,并研究了激光光斑尺寸和能量对LIBS信号的影响。本章另一部分重点论述了如何在EAST托卡马克上建立原位LIBS壁诊断系统。通过合理利用两个预留法兰接口、优化光路设计,实现了国际上首次将LIBS技术与具有偏滤器位型的全超导托卡马克相结合,可对EAST高场侧中平面1212cm2范围的第一壁进行三维LIBS元素分析。在2014年EAST实验周期中,使用LIBS实现了对壁表面元素变化的原位测量,成功获得了EAST壁表面的锂、钼、氘、氢、钨、镧、钛、硅、钠等元素信号；测定EAST在经过两次45 g的锂坩埚蒸发壁处理、锂弹丸注入实验以及194炮放电后,锂沉积层的厚度从4.0 μm增加到了9.0 μm；并获得了钼第一壁上的氘滞留比例(D/(H+D))在61%-64%之间。
[Abstract]:During the operation of Tokamak, the plasma material (Plasma-Facing Material, PFM) will be subjected to the steady / transient heat flow from the core plasma and the impact of the particle flow. A series of plasma interactions with the wall materials (Plasma Wall Interaction, PWI) process lead to the retention of fuel, the formation of impurities, the foaming, and the co deposition. It is one of the most important factors to determine whether the future ITER (International Thermonuclear Experimental Reactor) plan is successful or not. The linear plasma device can produce a steady / transient plasma beam with the plasma parameters of the tokamak edge plasma, which is produced by the plasma beam. The bombardment of PFM samples can simulate the PWI process in Tokamak, which is the main approach to the study of PWI simulation experiments. However, under the restriction of the diagnostic means, the study of the in-situ diagnosis of PWI has considerable challenges. Therefore, it is urgently needed to develop the PFM element in situ diagnosis technology for the linear plasma device and the Tokamak device. The real time in situ acquisition of element components on.PFM surface, one of the key problems, is very important for understanding the PWI process, revealing the PWI mechanism and putting forward the PFM optimization scheme. In this paper, the laser induced breakdown spectroscopy (Laser-Induced Breakdown Spectroscopy, LIB S) in situ wall diagnosis technology is developed for the straight line. Plasma devices Magnum-PSI, DUT-PSI and the in situ diagnosis of the elements of PFM samples in EAST (Experimental Advanced Superconducting Tokamak) in the Tokamak fusion device, and the key scientific problems of fuel retention, impurity generation and lithium-ion deposition in the PWI process are studied. The specific contents are as follows: in the second chapter, the Ma is introduced. The LIBS in-situ PFM diagnosis system established on the gnum-PS I linear plasma device can obtain PFM elements high time and space resolution LIBS spectral signals under 10-7 mbar background pressure. The successful establishment of this set of LIBS system is the first time that LIBS is first used in large linear plasma experimental devices. The high throughput deuterium produced by Magnum-PSI device is obtained. The deuterium retention and elemental distribution properties of pure tungsten, tungsten lithium carbide, original graphite tile and lithium fossil ink tile after irradiated by different doses of deuterium plasma were studied in situ (1024 m-2s-1) and in situ LIBS technique. It was found that lithium was obviously inhibited on the surface of tungsten. The experimental table showed that the lithium carbide was irradiated at 1.9 1025m-2 dose of deuterium plasma. The signal intensity of deuterium is obviously higher than the deuterium in the pure tungsten material, which is mainly caused by the strong chemical adsorption caused by the chemical reaction between lithium and deuterium. With the irradiation dose of the deuterium plasma increased to 6.21025 m-2, the samples of pure tungsten and lithium tungsten carbide have obvious deuterium retention saturation.LIBS depth analysis results. The signal of lithium, deuterium and hydrogen decreases with the depth of the depth, and the tungsten signal is strengthened with the depth first and then reaches the stable value. The deuterium plasma irradiation can make the lithium redeposition process and sputtering process reach the equilibrium.X ray photoelectron spectroscopy (X-ray Photoelectron Spectroscopy, XPS) off line analysis of the results of the distribution of each element obtained by LIBS and XPS. By analyzing the LIBS laser ablation pit of the samples of the tungsten lithium carbide, it is found that after the laser ablation, the deuterium plasma irradiation has made a significant redeposition of lithium. In the third chapter, the establishment of a low pressure DC cascade arc plasma beam device (DUT-PSI) is introduced. The luminescence intensity, the electron temperature, the vibration temperature and the rotational temperature of the shock wave region of the shock state are measured simultaneously. The results show that the plasma luminescence intensity is higher, the electron temperature is lower, the vibration temperature and the rotational temperature are higher in the compression zone of the shock state plasma. The temperature and the rotation temperature are higher. The plasma beam is in a remarkable non equilibrium state. After the optimization and upgrading of the structure of the DUT-PSI electrode, the device can produce a low temperature and high density plasma beam with the plasma parameters of the region of the partial filter. The electron temperature is 1-1.2 eV and the electron density can reach 21014 cm-3. It can be used to simulate the PWI related process of the lithium of tungsten. The three-dimensional distribution characteristics of lithium carbide and its impurity elements on the surface of the sample are studied by the chemical imaging system of the LIBS element. The study shows that the distribution of lithium, hydrogen, oxygen and argon on the surface of the tungsten carbide has a similar trend. The intensity of the hydrogen, oxygen and argon element is high in the region with high lithium signal intensity, but the distribution of the hydrogen, oxygen and argon element is high, but with the distribution of other elements such as tungsten. By off-line XPS spectrum analysis, the analysis results of LIBS chemical imaging are supported and the chemical states of elements in different locations such as the laser ablation zone and the tungsten carbide surface are analyzed. In the fourth chapter, the graphite tile of the filter in the 2012 EAST experiment period (the total discharge time of the watt 5621 times more than 50000 s) is carried out. The off-line LIBS analysis shows that deuterium retention on the graphite tile of the EAST filter is mainly caused by the lithium deuterium co deposition layer. The deuterium retention ratio (D/ (D+H)) increases with the depth first, and then stabilizes at about 0.17. This value can reflect the deuterium retention ratio at the filter tile at the EAST discharge. The effect of LIBS plasma collection area on LIBS signal acquisition is investigated. The spatial resolved LIBS analysis of common PFM samples, such as carbon, silicon and molybdenum, is analyzed. It is found that the signal intensity of carbon, silicon and molybdenum is from the laser ablated plasma due to the bremsstrahlung of the pulsed laser ablation plasma, the composite and the ultrasonic expansion process in the vacuum environment. The center to the edge is first raised and then dropped, and the effect of laser spot size and energy on the LIBS signal is studied. The other part of this chapter focuses on how to establish an in-situ LIBS wall diagnosis system on EAST tokamak. By rationally utilizing two reserved flange interfaces and optimizing the optical path setting, the LIBS technology and tools are realized for the first time in the world. With the combination of all superconducting tokamaks with partial filter position, the first wall of the first wall in the middle plane 1212cm2 range of the EAST high field side can be analyzed by the LIBS element. In the 2014 EAST experimental period, the in-situ measurement of the element changes on the wall surface was realized by LIBS, and the elements such as lithium, molybdenum, deuterium, hydrogen, tungsten, lanthanum, titanium, silicon, sodium and other elements in the surface of the EAST wall were successfully obtained. Signal; the thickness of the lithium deposition layer increased from 4 mu m to 9 Mu after the two 45 g lithium crucible evaporation wall treatment, the lithium pellet injection experiment and the 194 gun discharge, and the deuterium retention ratio (D/ (H+D)) on the first molybdenum wall (D/ (H+D)) was obtained between 61%-64%.

【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TL631.24;O536
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本文编号：1894591