Masahiro KOHIRA

Photophoresis, which is a light action to a particle, has been experimented under a parallel beam. Under a convergent beam, another light action "optical trap" is well known. Photophoretic force field under a convergent beam is very important information for making photophoretic trap, but have never been studied. In present study, we observed photophoresis of liquid smoke particles both on a small convergent laser beam and on a parallel beam, under the micro-gravity condition in order to avoid the convectional flow due to buoyancy. Experimental results indicate that photophoretic velocity scales as 0.43 about 1/2 power of the radiation intensity. That are new results for photophoretic experiments. In addition, we give a theoretical treatment to derive the power to be 1/2, by taking into account of the effect of a Marangoni convection.Meeting sponsors: The Science Council of Japan, The Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (ISAS)(JAXA)