Predictions and detection of the 鈥渁ccommodation鈥?forces on Janus particles subjected to directed radiation in a rarefied gas
- 作者：Sergey Beresnev ; sergey.beresnev@usu.ru ; Maria Vasiljeva ; Dmitry Suetin
- 关键词：Rarefied gas ; Accommodation coefficients ; Aerosol ; Photophoresis
- 刊名：Vacuum
- 出版年：2012
- 期刊代码：83_0042207x
- 类别：ph
- 出版时间：31 May, 2012
- 卷：86
- 期：11
- 页码：1663-1668
- 文件大小：294 K
摘要
The results of theoretical and experimental study of so-called 鈥渁ccommodation鈥?forces acting on particles with artificial asymmetry of surface properties in rarefied gas in the directed radiation field are presented. The gas-kinetic theory of phenomenon in the free-molecular regime for some different types of boundary conditions of gas-surface interactions is developed. The theory predicts appearance of the unusual force caused by the difference of the normal momentum accommodation coefficients on hemispheres of considered model Janus particle. The measurements conducted by the experimental technique with macroparticles have confirmed the existence of the accommodation forces affecting a particle together with the forces of radiometric photophoresis. The experimental results for the system 鈥渟teel particle-helium鈥?are in good agreement with theoretical predictions, and the ratio of the 鈥渁ccommodation鈥?forces to the photophoretic force does not exceed 3%. The estimations show that the 鈥渁ccommodation鈥?forces can be comparable in some cases with the radiometric photophoretic forces for micron-sized particles in stratosphere, but do not exceed the gravity force. The action of 鈥渁ccommodation鈥?forces, in our opinion, is not capable to provide effective vertical transport of aerosol particles against gravity at stratospheric altitudes.