Fizika Nizkikh Temperatur: Volume 46, Number 2 (February 2020), p. 164-171 ( to contents , go back )
Evolution of vortices on the normal He I surface
A.A. Pelmenev1,2, A.A. Levchenko1, and L.P. Mezhov-Deglin1
1Institute of Solid State Physics RAS, 2 Academician Ossipyan Str., Chernogolovka 142432, Russia
2Филиал Федерального государственного бюджетного учреждения науки Федерального исследовательского центра химической физики им. Н.Н. Семенова РАН, Черноголовка, 142432, Россия
Received November 15, 2019, published online December 27, 2019
Thermogravitational convection (Rayleigh–Bénard convection, RBC) is developed in a layer of normal He I heated on the top at temperatures below the maximum point of liquid 4He density T ≤ Tm = 2.178 K. It is determined experimentally that the emergence of RBC in the layer bulk is accompanied by the excitation of a vortex flow on the free He I surface. At the same time, in a cylindrical vessel small vortices form two large-scale vortices (vortex dipole) with time with the sizes limited by the cylin-drical vessel diameter. As the liquid temperature increases above Tm, the convective motion in the bulk of a non-uniformly heated layer decays rapidly, and vortex motion on the He I surface also persists. The results of the study of vortex system evolution with time in the absence of RBC (in the absence of energy pumping) have shown that during long-term observation (more than 1300 s) the non-linear interaction between weakly decaying large-scale vortices leads to small vortices emerging on the He I surface.
Key words: normal He I surface, Rayleigh–Bénard convection, large-scale vortices.