Surface-induced near-field scaling in the Knudsen layer of a rarefied gas

R. Gazizulin (1) , O. Maillet (1) , Xin Zhou (1) , A. Maldonado Cid (1) , Olivier Bourgeois (2) , E. Collin (1)

1 NEEL - UBT - Ultra-basses températures
2 NEEL - TPS - Thermodynamique et biophysique des petits systèmes

We report on experiments performed within the Knudsen boundary layer of a low-pressure gas. The non-invasive probe we use is a suspended nano-electro-mechanical string (NEMS), which interacts with 4 He gas at cryogenic temperatures. When the pressure P is decreased, a reduction of the damping force below molecular friction ∝ P had been first reported in Phys. Rev. Lett. 113, 136101 (2014) and never reproduced since. We demonstrate that this effect is independent of geometry, but dependent on temperature. Within the framework of kinetic theory, this reduction is interpreted as a rarefaction phenomenon, carried through the boundary layer by a deviation from the usual Maxwell-Boltzmann equilibrium distribution induced by surface scattering. Adsorbed atoms are shown to play a key role in the process, which explains why room temperature data fail to reproduce it.

Domaines: Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]

R. Gazizulin, O. Maillet, Xin Zhou, A. Maldonado Cid, Olivier Bourgeois, et al.. Surface-induced near-field scaling in the Knudsen layer of a rarefied gas. Physical Review Letters, 2018, 120 (3), pp.036802. ⟨10.1103/PhysRevLett.120.036802⟩. ⟨hal-01689108⟩