Probing helium interfaces with light scattering : from fluid mechanics to statistical physics

Pierre-Etienne Wolf (1) , Fabien Bonnet (1) , Sylvain Perraud (2) , Laurent Puech (1) , Bernard Rousset (2) , Pierre Thibault (2)

1 NEEL - HELFA - Hélium : du fondamental aux applications
2 SBT - Service des Basses Températures

We have investigated the formation of helium droplets in two physical situations. In the first one, droplets are atomised from superfluid or normal liquid by a fast helium vapour flow. In the second, droplets of normal liquid are formed inside porous glasses during the process of helium condensation. The context, aims, and results of these experiments are reviewed, with focus on the specificity of light scattering by helium. In particular, we discuss how, for different reasons, the closeness to unity of the index of refraction of helium allows in both cases to minimise the problem of multiple scattering and obtain results which it would not be possible to get using other fluids.

Mots clés: helium; hoizontal diphasic flow; atomization; heat transfer; porous media; disorder; aerogel; vycor; condensation; capillarity; isotherms; adsorption; desorption; light scattering

Domaines: Matière Molle [cond-mat.soft]; Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]; Optique [physics.optics]; Mécanique statistique [cond-mat.stat-mech]

Pierre-Etienne Wolf, Fabien Bonnet, Sylvain Perraud, Laurent Puech, Bernard Rousset, et al.. Probing helium interfaces with light scattering : from fluid mechanics to statistical physics. European Physical Journal E: Soft matter and biological physics, 2009, 28 (2), pp.183-198. ⟨10.1140/epje/i2008-10417-1⟩. ⟨hal-00294729⟩