Particle Lift by a Solid State Greenhouse Effect and Thermophoresis on Planetary and Protoplanetary Surfaces

行星和原行星表面的固态温室效应和热泳引起的粒子提升

• 批准号: 53838542
• 负责人: Professor Dr. Gerhard Wurm
• 金额: --
• 依托单位: Forschungsgruppe Experimentalphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/53838542?language=en
• 关键词: Particle; Lift; Solid; State; Greenhouse

It was discovered recently that illuminating a surface by light in a low pressure environment can efficiently lift small particles from a dust bed. This unexpected behaviour is based on two subtle effects. The first is a solid state greenhouse effect: the temperature maximum of an illuminated dust bed is located somewhat below the surface. The second effect is thermophoresis: particles in a rarefied gas with a warm and a cold side are dragged towards the cold side. This leads to particle lifting in a certain pressure and light intensity range. The requirements are met in late time protoplanetary disks and on the surface of Mars. As erosion mechanism, the effect has the potential to completely destroy a planetesimal close to a young star and recycle its material to form planets in other locations or to boost the growth of pre-existing protoplanets. The process might aid to lift particles from the surface of Mars into its atmosphere, and play a significant role in the planet’s cycle of dust. In a systematic study we investigate this new erosion and lifting mechanism. We study the dependency of particle lift on different parameters (material, particle size, porosities, gas properties, radiation etc.) in laboratory experiments and computer simulations. The results are applied to protoplanetary disks and planet formation. The significance as mechanism to lift dust on Mars is analyzed. In the case of Mars, dust lift-off might occur by sunlight or it might be used technologically to remove dust on purpose from sensitive surfaces during Mars exploration.

最近发现，在低压环境下用光照射表面可以有效地将微小颗粒从粉尘床上清除出来。这种意想不到的行为基于两个微妙的影响。第一种是固态温室效应：被照亮的尘埃床的最高温度位于地表以下。第二种效应是热潜水作用：稀薄气体中的粒子被拖向冷端。这导致粒子在一定的压力和光照强度范围内上升。这些要求在晚些时候的原行星盘和火星表面得到了满足。作为侵蚀机制，这种效应有可能完全摧毁一颗靠近年轻恒星的小行星，并回收其物质，在其他地方形成行星，或促进先前存在的原行星的生长。这一过程可能有助于将粒子从火星表面提升到其大气层中，并在该行星的尘埃循环中发挥重要作用。在系统的研究中，我们研究了这种新的侵蚀和抬升机制。我们研究了颗粒升力与不同参数(材料、颗粒大小、孔隙率、气体性质、辐射等)的关系。在实验室实验和计算机模拟中。这些结果被应用于原行星盘和行星的形成。分析了它作为火星扬尘机制的意义。在火星的情况下，扬尘可能发生在阳光下，或者在火星探测期间，它可能被用来故意从敏感表面上去除灰尘。