While the shear viscous motion of the normal fluid component causes the energy loss of the fourth sound resonance in superfluid 3He confined in narrow pores, it is not yet clear what causes the energy loss of the fourth sound in the aerogel system. We prepared two aerogel samples of 99.0% and 97.5% porosities, which were directly grown in sintered silver sponges and performed the fourth sound resonance experiments. We found that the energy loss of the fourth sound resonance in aerogel is much smaller than that in pure liquid 3He, showing that the mean free path of 3He quasiparticles is strongly suppressed by aerogel strands. Such behavior is explained with the frictional flow. The temperature dependence of the frictional relaxation time will be discussed.
ASJC Scopus subject areas
- Physics and Astronomy(all)