四极质谱计在超导托卡马克装置上的应用

四极质谱计广泛用于托卡马克装置上,用来监测聚变装置的真空品质,为真空系统的状态提供判断依据。本文介绍了四极质谱计在全超导非圆截面托卡马克装置(EAST)上的多种应用,为聚变装置的第一壁处理和聚变过程中多种残余气体成分含量变化提供数据。实验证明四极质谱计是EAST装置真空系统运行、等离子体与器壁相互作用研究过程中一种较为基础的测量工具。     

聚变堆装置中面向等离子体材料钨涂层的研究进展

钨具有高的熔点、不与氚发生共沉积、与等离子体好的兼容性和低的腐蚀率等优点,是最有前景的一种面向等离子体材料.为了解决面向等离子体材料的制备及其与热沉材料连接问题,涂层技术在实验聚变堆装置中得到广泛应用.评述了目前实验聚变堆装置中面向等离子体材料钨涂层的研究进展.     

HT-7托卡马克中锂第一壁研究的先行试验

为了抑制等离子体杂质和减少粒子再循环,获得高品质的等离子体,HT-7超导托卡马克将进行锂限制器实验。为此需要在实验台上开展一些先行试验,以掌握锂材料操作的关键工艺;在加热和直流辉光放电下,借助光谱仪及膜厚仪得到温度与锂熔化、挥发、沉积之间的关系。实验表明在锂温度低于300℃的情况下,锂挥发不明显;从300℃到360℃,挥发速度逐渐加快;当锂温度高于370℃,锂挥发急剧增加。利用蒸发镀膜和直流辉光放电等离子体镀膜,在真空室壁沉积了约300nm的锂膜,装置真空明显改善,表明锂膜对各种气体有很强的吸附和抑制作用。实验表明锂是托卡马克装置第一壁的理想材料之一,可以用于抑制等离子体中杂质,降低氢同位素再循环,提高等离子体性能。采用锂作为HT-7限制器,有必要在安装过程中采用氩气保护,以避免锂的氧化,同时在实验期间应避免锂限制器温度过高,以防止锂的快速蒸发。     

HT-7托卡马克全金属壁及锂化条件下辉光放电清洗的研究

辉光放电清洗被广泛应用于聚变装置的壁处理,但是对于未来国际热核实验反应堆全金属壁条件下的实验运行,需要积累更多经验。HT-7托卡马克从2011年开始,采用全金属第一壁,包括钼限制器和不锈钢内衬,而且具有抑制杂质和降低再循环功能的锂化,也被HT-7用为常规的壁处理。研究发现,辉光放电清洗对于锂化金属壁同样具有杂质清除效果。全金属壁条件下,He辉光对于H,O,C的清除率分别达到4.2×1023,1.1×1022,2.4×1021atoms/h,锂化条件下,He辉光的清除率具有相似水平。此外,文章还研究了不同种类气体和壁温对于辉光效果的影响。先进超导托卡马克实验装置(EAST)不久也会采用钨偏滤器和钼第一壁,因此本文研究的内容对于全金属壁的EAST也同样具有重要意义。     

EAST装置等离子体放电排气及其成分分析

在磁约束聚变装置中,高温等离子体放电中粒子的实时排出不仅可以减少燃料粒子在第一壁的滞留,还可以排出一定的杂质,有利于下一次等离子体放电的实现。对于未来聚变装置,如ITER,还有利于减少氚滞留导致的装置安全问题。本文根据EAST全超导托卡马克装置不同等离子体放电参数和不同第一壁条件下的放电实验,主要研究了等离子体破裂和锂化壁处理对粒子排出的影响。初步研究表明,等离子体破裂导致更多的粒子排出,并且排出气体中杂质含量降低;而锂化壁处理可以减少粒子排出,但杂质含量增高。这些研究可以为未来高参数等离子体运行找到一种实时降低壁杂质及减少壁滞留的方法提供参考,也对研究等离子体参数对等离子体排灰气成分分析有着参考价值。     

聚变装置用石墨材料的研究动向

聚变装置用石墨材料的研究动向宋进仁翟更太刘朗（中国科学院山西煤炭化学研究所，太原０３０００１）０前言早期的聚变装置，其限制器和壁保护材料多用高熔点金属和金属碳化物。随着聚变装置向大型化发展，反应温度提高，对限制器和壁保护材料性能提出了更高的要求，早期...     

快速环形放电装置中等离子体对器壁的作用

等离子体与器壁相互作用,严重地影响了托卡马克装置等离子体指标的提高。为此,在许多托卡马克装置和其他类型的聚变研究装置上用各种测量工具来观察研究等离子体与器壁间的相互作用。本文叙述在一个硬质玻璃器壁的快速环形放电装置上用质谱分析研究在高功率和低功率放电时等离子体对器壁的作用。     

HT—7U装置第一壁抗热冲击SiC厚膜涂层研究

为实现 HT－ 7U装置长脉冲运行的物理目标,在碳石墨第一壁材料的改性研究中和为保证在稳定的长平顶阶段对大部分杂质和再循环的控制,提出了研制抗等离子体溅射腐蚀的梯度功能涂层的概念。研究了通过化学气相转化 CVR和化学气相渗透 CVI 2种技术实现 SiC厚膜梯度涂层的方法,通过实验研究发现 CVI法实现的 SiC涂层有更厚、更致密、更好的梯度性和很好的抗热冲击等综合性能,适于作为 HT－ 7U装置第一壁高通量部件上的保护涂层。     

EAST装置等离子体放电真空室真空泄漏研究

真空系统是EAST全超导托卡马克装置安全稳定运行的基础保障系统,真空泄漏会影响等离子体放电并对真空设备造成严重的损坏。随着EAST逐步地升级与改造,真空系统变得更加复杂,同时设备逐渐老化,导致泄漏的风险逐年增大。介绍了EAST内真空抽气系统、真空测量站及漏率实时监测系统。根据真空室压力变化数据,采用静态升压法分析了内真空室漏放率,计算出内真空室在等离子体放电前整体漏放率约为2.2×10^-4 Pa·m³/s。基于历年发生泄漏故障时的压力和残气成分数据,对EAST装置内真空室在不同运行阶段的不同类型泄漏进行了分析。研究发现,发生的泄漏位置不同、泄漏介质不同、器壁条件不同,在残气成分特征上表现差异较大。根据泄漏的特点,采取了不同的泄漏处理方式。研究结果可为及时准确地判断和处理EAST及未来聚变堆真空室的泄漏提供参考。     

不同辐照粒子下钨及钨合金辐照损伤行为的研究进展

研究核聚变、准稳态等离子体下面向等离子体材料的辐照行为,发展适合于先进实验超导托卡马克(EAST)、国际热核聚变实验堆(ITER)和中国聚变工程实验堆(CFETR)长脉冲高参数运行乃至未来聚变反应堆稳态运行的高性能面向等离子体材料是当前核聚变研究一项艰巨而又紧迫的任务。钨因具有高熔点、高导热率、低溅射腐蚀速率、高自溅射阀值以及低蒸气压和低氚滞留等优异性能,被认为是聚变装置最具有前景的面向等离子体材料。综合评述了钨及钨合金在不同辐照粒子下损伤行为的最新研究进展。粒子辐照造成的微观缺陷在钨及钨合金内部累积,辐照造成缺陷的形成和数量与钨基材料颗粒微观结构、第二相成分等密切相关,辐照缺陷情况各异。同时,辐照粒子种类、能量、剂量和温度等辐照条件都会对钨材料辐照后的形貌特征和缺陷产生重要影响。     

Testing of low-Z-coated limiters in tokamak fusion devices

Coatings of materials with low atomic number Z are being developed for application both in experimental tokamak devices such as ISX and TFTR and for possible use on various components of large power-producing controlled thermonuclear reactors. A suitable coating has the potential of improving the plasma energy balance by lowering the atomic number of the impurities injected by plasma-wall interactions. This results in a decrease in plasma radiation losses and improved plasma stability. The coatings will be subjected to a severe environment and must be able to withstand physical erosion, chemical erosion, thermal shock, thermal fatigue and arcing without rapid degradation or loss of adhesion.Extensive testing on a laboratory scale was used to select the coatings most suitable for this environment. From this testing, which included pulsed electron beam heating, low energy ion bombardment and arcing, chemically vapor-deposited coatings of TiB₂ and TiC on Poco graphite substrates were selected and tested as limiters in ISX. Both limiter materials gave clean stable reproducible tokamak discharges on the first day of operation. After an exposure of 1 week, the TiC limiter showed only superficial damage with no coating failure. The TiB₂ limiter showed some small areas of coating failure. TiC-coated graphite limiters were also briefly tested in the tokamaks Alcator and PDX with favourable results.     

等离子喷涂碳化硼/钼涂层氚的滞留性能研究

为了保证核能源的使用安全, 对氚在第一壁材料表面的滞留数量以及深度进行定量表征非常重要。在本研究中, 制备了一系列潜在的第一壁材料B₄C/Mo 涂层, 并采用成像板(IP)和β射线激发X射线(BIXS)法对其表面的氚滞留情况进行了测定。IP 图像表明, 涂层表面吸附的氚含量遵循以下顺序: B₄C>BM15>BM5>Mo。而BIXS结果进一步表明, 对于B₄C涂层, 大部分氚扩散到了涂层内部; 而对于其他三种涂层, 氚仅在其表面发生吸附。扫描电镜(SEM)结果显示, B₄C涂层气孔率最高, 而其他三种涂层尽管气孔率较低, 但其截面仍能观察到大量气孔和微裂纹的存在。涂层中的这些缺陷为氚的吸收和扩散提供了通道, 而气孔与微裂纹的尺寸最终决定了氚在涂层表面的吸附数量。实验结果还表明, 涂层杂质成分Ti的存在也对氚的滞留产生了一定影响。     

聚变堆中面向等离子体材料的研究进展

受控热核聚变能是公认的可以有效解决人类未来能源需求的主要途径之一,经过多年的努力,其研究已经取得很大进展,进入了从物理可行性向工程可行性的验证阶段.决定核聚变能未来发展的一个关键问题是相关的材料问题,尤其是面向等离子体材料的发展.评述了国内外目前核聚变实验装置中面向等离子体材料的研究进展.     

EAST装置2 kW/4.5 K氦制冷机透平膨胀机的测试

EAST装置于2006年成功进行工程调试和物理实验,全部超导磁体均已冷却到液氦温度,并获得了第一次等离子体.低温系统共有4台俄制氦透平膨胀机,通过气体绝热膨胀来获得低温.实验表明4台透平的设计满足EAST装置对冷量的需求,透平效率略低于设计值,流量比设计值大.介绍了EAST低温系统中4台透平膨胀机的设计参数、启动过程和运行,并对透平膨胀机在运行过程中的性能参数进行测试和分析.     

Microstructure and solid particle erosion of carbon-based materials used for the protection of highly porous carbon–carbon composite thermal insulation

Multiparticle erosion tests were performed on candidate coating (colloidal graphite paints) and cladding (dense carbon–carbon composites and graphite foil) materials employed to protect porous carbon–carbon composite thermal insulation in vacuum and inert-gas furnaces that utilize inert gas quenching. The dependence of the erosion rate on the angle of incidence of the erodent was examined and related to the microstructure and the mechanisms of material removal as observed by SEM. In addition, the effect of a thin chemical vapour deposited (CVD) carbon layer on top of a colloidal graphite paint coating and a graphite foil clad was investigated. The coating and cladding materials displayed a greater erosion resistance at all angles of incidence compared to the porous carbon–carbon composite. In general, the greatest erosion rate was found at an angle of incidence of 90°, where the erodent stream is perpendicular to the erosion surface, and brittle fracture was the predominant mechanism of material removal. The exception was the graphite foil material which displayed maximum erosion at an angle of incidence of 60°. For this material, two mechanisms were effective: disruption of the graphite flakes, which are mainly held together by mechanical locking, and a ploughing-like mechanism. The addition of a thin CVD carbon layer to colloidal graphite paint improved performance, whereas the erosion resistance of the graphite foil was slightly degraded as the CVD layer was too thin to prevent the ploughing-like mechanism. This revised version was published online in November 2006 with corrections to the Cover Date.     

Ablation characteristics of a 4D carbon/carbon composite under a high flux of combustion products with a high content of particulate alumina in a solid rocket motor北大核心CSCD

The ablation behavior of a four-directional carbon/carbon (C/C) composite was examined in a lab-scale solid rocket motor under a high flux of combustion products containing a high content of particulate alumina. The composite consisted of three braided carbon fiber bundles at 120 to each other in the XY plane and a hexagonal array of carbon rods in the Z direction, all in a pitch carbon matrix. The rods consisted of a unidirectional array of the same carbon fibers in a pitch carbon matrix The composite was placed in the rocket motor with its XY plane perpendicular to the gas flow and its ablation rate, ablation behavior and microstructure were investigated. The flow field of the combustion products was simulated by solving the Reynolds-averaged NavierStokes equations. A deep pit was formed on the surface of the composite, the center of which coincides with the simulated particle accumulation area. The mechanical erosion was significantly increased when the particle impact velocity exceeded 96. 82 m/s. The carbon rods were more susceptible to erosion than the surrounding fiber bundles. The maximum ablation rates of the carbon rod and bundles were increased almost by an order of magnitude by increasing the particle impact velocity by a factor of two. Numerous crater-like pores on the ends of the carbon rods were formed by alumina particle impaction, and the tips of the fibers in the carbon rods were almost flat and lower than the surrounding matrix. Heating caused by the particle impact increased the thermal oxidization and hence the overall ablation rate of the composite.     

Ordered carbon nanotubes for optical power limiting devices

The electrospinning (ES) process was used to fabricate composite nanofibers (NFs) of poly(methyl methacrylate), PMMA, with embedded multiwalled carbon nanotubes (MWNTs) from a solution of PMMA in N,N-dimethylformamide (DMF) with homogenously dispersed MWNTs. Using both the sinklike and the elongation flows in the electrospinning process, we aligned the carbon nanotubes (CNTs) along the fiber axis. The NFs were subsequently deposited in an aligned manner on a glass surface using the electrostatic lens created by the edge of a rotating wheel collector. Semitransparent optical power limiter (OPL) films (~50% transmittance) were fabricated using an optically compatible polymeric resin infiltrated into the collected NFs. These comprised oriented NFs with different carbon nanotube loadings and film thicknesses. The OPLs exhibited high limiting abilities, with a limiting threshold of 1.5 J/cm(2) at about 50% linear transmittance. Some degree of polarization was also achieved, but significantly lower than expected because of the NF orientation.     

Optimum dispersion conditions and interfacial modification of carbon fiber and CNT–phenolic composites by atmospheric pressure plasma treatment

Electric resistance measurements were used to determine the optimal dispersion conditions for carbon nanotubes (CNTs) in phenolic resins. Plasma treatment is frequently used to modify carbon fiber surfaces to improve adhesion of the fibers to matrices. Such treatment might also influence carbon fiber tensile strength. In order to determine the effect of atmospheric pressure plasma treatment on carbon fiber tensile strength and interfacial bonding strength, change in tensile strength of the fiber was studied at different gage lengths before and after the plasma treatment. The wettability of carbon fibers was improved significantly after only 10 s of plasma treatment. Such plasma treatment resulted in a decrease in the advancing contact angle from 65° to 28°. Surface energies of carbon fiber and CNT–phenolic composites were measured using the Wilhelmy plate technique, indicating that the work of adhesion between plasma treated carbon fibers and CNT–phenolic composites was higher than it before plasma modification. The interfacial shear strength (IFSS) and apparent modulus were also increased by plasma treatment of the carbon fibers.     

Erosion of amorphous carbon layers in the afterglow of oxygen microwave plasma

We present a study of the interaction of amorphous hydrogenated carbon deposits (a-C:H) with neutral oxygen atoms. Samples of a-C:H were exposed to an atomic oxygen rich atmosphere at surface temperatures from 473 K to 623 K. The source of atomic oxygen was microwave plasma, created in oxygen at pressures between 50 Pa and 200 Pa by means of a surfatron. The density of neutral oxygen atoms reached up to 4 ∙ 10²¹/m³. The densities of neutral atoms were measured by means of a catalytic probe. The erosion process was monitored by means of an infrared pyrometer. At each sample surface temperature, the erosion rates were found to linearly increase with the atomic oxygen density. This allowed us to calculate the reaction rate coefficient at corresponding surface temperatures. The reaction rate coefficient was found to increase exponentially with the sample surface temperature.