Hypervelocity capture of particles in aerogel: Dependence on aerogel properties
Hypervelocity capture of particles in aerogel: Dependence on aerogel properties
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DOI：
10.1016/j.pss.2008.11.004
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发表时间：
2009-01-01
影响因子：
2.4
通讯作者：
Cole, M. J.
中科院分区：
文献类型：
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作者：
Burchell, M. J.;Fairey, S. A. J.;Cole, M. J.
报道了在175-763K的环境温度下，高速(超高速)粒子在气凝胶中的捕获。这是以前主要侧重于在实验室环境温度下进行实验的工作的延伸，尽管气凝胶是用于可能经历一定温度范围的空间环境中的宇宙尘埃捕集室(例如，美国宇航局在1.81AU收集尘埃的星尘飞行任务和可能的火星大气采样飞行任务)。轨道长度(归一化为冲击器大小)在175-600K范围内没有发现显著变化，尽管在763K发现显著减少(30%)。相比之下，入口孔直径只有在400K以下才保持不变，超过400K，入口孔直径会发生高达50%的突变。实验也是在正常的实验室温度下进行的，使用了广泛的气凝胶密度和颗粒大小。研究发现，归一化为颗粒大小的轨道长度与气凝胶密度成反比。这是一种幂定律依赖关系，而不是像以前报道的那样是线性的，较长的磁道密度较低。在捕获过程中发现玻璃弹丸(最大尺寸为100微米)受到不同程度的损坏。除了众所周知的获得熔融气凝胶涂层(部分或全部)之外，机械损伤还包括点蚀和子午线断裂。较大的(500 PM直径)不锈钢球在捕获过程中也显示出损坏。在这种情况下，会发生熔化和烧蚀，表明撞击过程中的表面温度超过1400摄氏度。据报道，气凝胶本身对粒子通过它的反应。轨道周围出现扇状断裂是由于锥体破裂，类似于正常密度的玻璃，不同的是，这是一个重复的过程，因为颗粒通过气凝胶。(C)2008爱思唯尔有限公司。保留所有权利。
Capture of high-speed (hypervelocity) particles in aerogel at ambient temperatures of 175-763 K is reported. This extends previous work which has mostly focussed on conducting experiments at ambient laboratory temperatures, even though aerogels are intended for use in cosmic dust capture cells in space environments which may experience a range of temperatures (e.g., the NASA Stardust mission which collected dust at 1.81 AU and putative Mars atmospheric sampling missions). No significant change in track length (normalised to impactor size) was found over the range 175-600 K, although at 763 K a significant reduction (30%) was found. By contrast, entrance hole diameter remained constant only up to 400K, above this sudden changes of up to 50% were observed. Experiments were also carried out at normal laboratory temperature using a wide range of aerogel densities and particle sizes. It was found that track length normalised to particle size varies inversely with aerogel density. This is a power law dependence and not linear as previously reported, with longer tracks at lower densities. Glass projectiles (up to 100 mu m size) were found to undergo a variety of degrees of damage during capture. in addition to the well known acquisition of a coating (partial or complete) of molten aerogel the mechanical damage includes pitting and meridian fractures. Larger (500 pm diameter) stainless steel spheres also showed damage during capture. In this case melting and ablation occurs, suggesting surficial temperatures during impact in excess of 1400 degrees C. The response of the aerogel itself to passage of particles through it is reported. The presence of fan-like fractures around the tracks is attributed to cone cracking similar to that in glasses of normal density, with the difference that here it is a repetitive process as the particles pass through the aerogel. (C) 2008 Elsevier Ltd. All rights reserved.