Experiments of superfluid /sup 4/He evaporation

Journal Article · Sun Oct 01 04:00:00 EDT 1978 · Phys. Rev., B: Solid State; (United States)

DOI:https://doi.org/10.1103/PhysRevB.18.3096· OSTI ID:6580023

Balibar, S; Buechner, J; Castaing, B; Laroche, C; Libchaber, A

A study of the evaporation of superfluid /sup 4/He using the heat-pulse technique, is presented; working at low temperature, 0.1 < T < 0.6 /sup 0/K, the phonon and the roton fluids are decoupled. We observed atoms evaporated by a phonon second-sound pulse between 0.4 and 0.6 /sup 0/K. The temperature dependence of the signal is interpreted by a simple model where one phonon of energy E emits one atom of energy E - E/sub 0/ (E/sub 0/ = 7.15 /sup 0/K is the atomic binding energy in the liquid). At lower temperature, down to 0.1 /sup 0/K, a ballistic-phonon regime is observed, associated with no detected evaporation. Concerning rotons, we observe well-defined signals due to atoms evaporated by them. Analyzing the arrival time as a function of the liquid path, we propose an evaporation process such as one roton of energy E emits one atom of energy E - e/sub 0/. This leads to a minimum kinetic energy of 1.5 /sup 0/K for the evaporated atoms, effectively observed. An estimation of the roton mean free path is deduced and a maximum roton velocity of 160 +- 10 m sec/sup -1/ is observed.

• Research Organization: Groupe de Physique des Solides de l'Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris 05, France
• OSTI ID: 6580023
• Journal Information: Phys. Rev., B: Solid State; (United States), Journal Name: Phys. Rev., B: Solid State; (United States) Vol. 18:7; ISSN PLRBA
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
EVAPORATION
EVEN-EVEN NUCLEI
FLUIDS
HELIUM 4
HELIUM II
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
NUCLEI
PHASE TRANSFORMATIONS
PHONONS
QUANTUM FLUIDS
QUASI PARTICLES
ROTONS
SECOND SOUND
STABLE ISOTOPES