Vol. 21, issue 02, article # 5

Abstract:

The results of theoretical and experimental investigations of so-called accommodation forces (gravito-photophoresis) acting on particles with an asymmetry of surface properties in a rarefied gas in the directed electromagnetic radiation field are presented. The gas-kinetic theory of the phenomenon in the free-molecular regime predicts an occurrence of an unusual force, caused by the difference in accommodation coefficients of the normal pulse (momentum) on model particle hemispheres, which can be comparable with radiometric photophoretic forces for micron-size particles in stratosphere. The measured values of the force for steel particle in helium by a technique of model thermal-physics experiment agree well with theoretical predictions. The ratio of accommodation force to the radiometric photophoretic force in experiment does not exceed 3%.