Initial growth phase of W-fuzz formation in ultra-long pulse helium discharge in LHD
Initial growth phase of W-fuzz formation in ultra-long pulse helium discharge in LHD
复制标题
LHD超长脉冲氦气放电中W-绒毛形成的初始生长阶段
DOI：
10.1016/j.nme.2016.11.023
复制
发表时间：
2017
影响因子：
2.6
通讯作者：
S. Nagata
中科院分区：
文献类型：
--
作者：
M. Tokitani;S. Masuzaki;H. Kasahara;Y. Yoshimura;R. Sakamoto;N. Yoshida;Y. Ueda ;T. Mutoh;LHD Experiment Group ;S. Nagata
为了证实在大尺寸等离子体约束装置中氦等离子体辐照形成的钨纤维状纳米结构（W-fuzz），将尺寸为80 × 20 × 1. 5 mm 3的钨块插入到大尺寸等离子体约束装置（LHD）的偏滤器腿位置。然后，它暴露在偏滤器等离子体在超长脉冲氦放电，共10,190秒。偏滤器等离子体的宽度、入射离子能量和总注量预计分别为100-200 eV和105 × 1025 He/m2（撞击位置）。用红外相机监测钨试样的表面温度。偏滤器撞击点的典型表面温度估计约为1900 - 2300 K。暴露后，钨纤维状纳米结构（W-绒毛）的初始生长阶段能够在钨表面上被识别。在偏滤器撞击点的中心区域能够识别出W-绒毛结构的最精细的初始生长阶段，其中氦的保留量估计为108 × 1021 He/m2。这项研究是第一个同时评估的W-绒毛生长和定量的氦保留在大型等离子体约束装置。
In order to confirm the formation of a tungsten fiberform nanostructure (W-fuzz) by helium plasma exposure in the large-sized plasma confinement device, the bulk tungsten with the size of 80 × 20 × 1.5 mm3was inserted into the divertor leg position in the Large Helical Device (LHD). Then, it was exposed to the divertor plasma during the ultra-long pulse helium discharges with 10,190 s in total. The width of the divertor plasma, incident ion energy and total fluence were expected to be ∼2 cm, 100–200 eV and ∼5 × 1025He/m2(strike position), respectively. The surface temperature of the tungsten specimen was monitored by IR camera. The typical surface temperature of the divertor strike point was estimated to be around 1900 ∼ 2300 K. After the exposure, an initial growth phase of tungsten fiberform nanostructure (W-fuzz) was able to be identified on the tungsten surface. The finest initial growth phase of the W-fuzz structure was able to be identified on the central region of the divertor strike point, where retention amount of helium was estimated to be ∼8 × 1021He/m2. This study is the first simultaneous evaluation of the W-fuzz growth and quantification of the helium retention in the large-sized plasma confinement device.