Tungsten and CFC degradation under combined high cycle transient and steady state heat loads
Tungsten and CFC degradation under combined high cycle transient and steady state heat loads
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DOI：
10.1016/j.fusengdes.2012.02.106
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发表时间：
2012-08-01
影响因子：
1.7
通讯作者：
Thomser, C.
中科院分区：
文献类型：
--
作者：
Loewenhoff, Th.;Linke, J.;Thomser, C.
在ITER偏滤器寿命内，由于边缘局部模式（I型ELMs），预计在H模式操作期间会发生数百万次瞬态事件。这些将把它们的能量存款在面向等离子体的材料上，这些材料被预热到各种表面温度，这取决于在相应位置处的稳态热负荷（SSHL），从而导致协同效应。利用ITER相关功率密度（约0.5 GW/m（2））和脉冲宽度（0.5 ms）的电子束装置模拟了ELM类热负荷。同时，附加的SSHL被施加以获得不同的基础温度。在主动冷却纯钨和碳纤维复合材料（CFC）NB 41上进行了实验，对钨和CFC分别施加10（3）-10（6）个持续时间为0.5ms的脉冲，功率密度为0.14- 0.55GW/m（2）和0.55- 0.68GW/m（2）。钨的表面温度约为200摄氏度、400摄氏度和700摄氏度，CFC的表面温度约为450摄氏度。裂纹形成之前，钨由于塑性变形的粗糙化。在T-surf接近200 ℃的情况下，裂纹快速扩展（脆性材料），而裂纹边缘周围的缓慢扩展和再结晶表明在较高温度下的疲劳损伤。与钨相比，CFC表现出更高的损伤阈值。(C)2012爱思唯尔有限公司版权所有。
Within the ITER divertor lifetime millions of transient events are expected during H-mode operation due to edge localized modes (type I ELMs). These will deposit their energy on plasma facing materials that are pre-heated to various surface temperatures, depending on the steady state heat load (SSHL) at the respective location, leading to synergistic effects. An electron beam facility was used to simulate ELM-like heat loads with ITER relevant power densities (approximate to 0.5 GW/m(2)) and pulse duration (0.5 ms). At the same time additional SSHL was applied to obtain different base temperatures. Experiments were performed on actively cooled pure tungsten and the carbon fiber composite (CFC) NB41, applying 10(3)-10(6) pulses of 0.5 ms duration with a power density of 0.14-0.55 GW/m(2) and 0.55-0.68 GW/m(2) on tungsten and CFC, respectively. Surface temperatures were about 200 degrees C, 400 degrees C and 700 degrees C for tungsten and about 450 degrees C for CFC. Crack formation in tungsten was preceded by roughening due to plastic deformation. In case of T-surf approximate to 200 degrees C cracks propagated comparably fast (brittle material), while slow propagation and recrystallization around the crack edges indicated fatigue damage at higher temperatures. Compared to tungsten, CFC showed a higher damage threshold. (C) 2012 Elsevier B.V. All rights reserved.