刘翔，谌继明，张年满，潘传红，刘永 王站宏，王莉核工业西南物理研究院 (xliu@swip.ac.cn) 宁夏东方有色金属集团公司Jochen Linke, Manfred RoedigInstitute for Materials and Processes in Energy System, Forschungszentrum Juelich Gmbh, Germany

中国高纯铍作为 ITER候选的面对等离子体材料的热负荷评估 第十三届全国等离子体科学技术会议 2007, 8, 20-22, 成都

核工业西南物理研究院

刘翔，等 . 第十三届全国等离子体科学技术会议 2007, 8, 20-22, 成都

Abstract 铍，特别是美国 Brush Wellman 公司生产的真空热压高纯铍已被选定为 ITER 第一壁包层的保护材料。中国作为 ITER 的成员国之一，正在发展 ITER 级的真空热压铍材。为了能够被 ITER 所采用，我们的铍材还必须通过 ITER 国际组（ IT ）的资格认证。 经过国内几家单位的联合攻关 ，目前一种高纯的真空热压铍材 CN-G01 已经被成功开发，其氧化铍的含量小于 1 wt. % ，总的延伸率在 3 % 左右。 . 按照 ITER 的要求，我们测量了铍材的热力学性能，如成分、密度、比热、热导率、热膨胀系数，泊松比，抗拉强度等，它们都基本满足了 ITER 的要求。 除了材料的热力学性能外， ITER 最终的认证标准是高热负荷性能。为了能够顺利地通过 ITER-IT 的严格测试，在铍材样品送检之前，有必要对我们的铍材进行预评估。由于铍的毒性，实验设备和环境都有严格的要求，因此该评估实验在德国 FZJ 研究所的电子束热负荷实验装置 JUDITH-1 上进行。在这次实验中，我们主要考察了铍材料在等离子体破裂条件下的损伤行为。实验样品的尺寸是 10 10 5 mm3 ，电子束辐照面积是 4 4mm2 ，样品的吸收能量密度为 0.22-1.5 GW/m2 ，脉冲宽度为 1-5 ms ，单次和多次热冲击实验被采用。实验后样品表面的损伤通过光学和电子显微镜观察，热腐蚀特征由三维激光形貌仪（ laser profiler ）进行测量。通过与美国 S-65C 级铍的比较实验，发现我们的铍材料在某些方面还需要进行改进。1, Experimental1.1 Basic properties of CN-G01 beryllium

Main parameters:

Power: 60 kW, 150keV, 400 mA.

Scanning frequency: up to 20 kHz

Thermal fatigue: 10s pulse duration (typical)

Disruption simulation: 5-1000ms,

Disruption: 5 ms, 44 mm2,

VDE: up to 1000 ms, 1515 mm2.

Measurements: online absorbed beam current and fast pyrometry.

2, Experimental condition and main results

3, Results and analysis3.1, Optical microscopy observation

Fig.2, Surface topography of No. 9# sample after one shot at a heat flux of 0.55 GW/m2, 5 ms.

Fig.3, Surface topography of No. 6# sample after 1000 shots at a heat flux of 0.5 GW/m2, 1 ms.

Fig.4, Surface topography of No. 12# sample after one shot at a heat flux of 0.8 GW/m2, 5 ms.

3.2, Scanning electron microscopy observation

Fig.5, Cracks originate after one shot of 0.33 GW/m2, 5 ms pulse (No. 2#).

Fig.6, Surface roughening after 100 shots under a heat flux of 0.33 GW/m2, 5 ms (No. 3#).

Fig.7, Intergranular cracking after 1 shot of a heat flux of 0.48 GW/m2, 5 ms (No. 4#).

Fig. 8, Cracks along machining direction. (No.8#, 0.55 GW/m2, 5 ms, 1 shot)

Fig. 9, Surface melting and cracking creation at severe heat load. (No.15#, 1.5 GW/m2, 5 ms, 1 shot)

Fig. 10, A clear view of Surface melting zone (No.15#, 1.5 GW/m2, 5 ms, 1 shot)

3.3, 3D laser profiler analysis

No. 7# sample, 0.48 GW/m2, 5 ms, 100 shots

No. 10# sample, 0.66 GW/m2, 5 ms, 100 shots

No. 15# sample, 1.5 GW/m2, 5 ms, 1 shots

ConclusionsA kind of Chinese high purity beryllium, namely CN-G01 grade beryllium has been developed by means of vacuum hot press, its chemical composition and thermo-mechanical properties basically satisfied the ITER’s specification.

A heat load experiment of Chinese vacuum hot press beryllium CN-G01 was performed in a scanning electron beam facility JUDITH-1 (Germany) in order to investigate the damage behavior under fusion plasma disruption conditions.

Experimental results indicated that cracking was the characteristic damage of CN-G01 beryllium, and round cracks appeared in most cases, which might be due to the relatively low elongation rate and tensile strength of CN-G01 beryllium compared with S-65C grade beryllium made by Brush Wellman Inc. USA, in particular the performance at high temperature. In addition, in some cases, cracks along machining direction was found, the reason was still unclear.

Crack transportation behavior was a critical issue, which will be closely related to ITER’s acceptable standard. The metallography observation was under way, it was expected that the surface cracks could not penetrate into deep layer, otherwise necessary modification of beryllium fabrication techniques have to be considered.

Chemicalelements Be BeO (%) Al C Fe Mg Si Other metallic

elements1 ≥99% 0.750 0.006 0.060 0.050 0.003 0.009 <0.042 ≥99% 0.890 0.005 0.072 0.040 0.002 0.009 <0.043 ≥99% 0.920 0.006 0.065 0.055 0.005 0.010 <0.044 ≥99% 0.910 0.003 0.063 0.060 0.005 0.010 <0.045 ≥99% 0.930 0.004 0.075 0.045 0.006 0.010 <0.04

1.2 Experimental facility