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
E-mail: pelmenevaa@gmail.com; levch@issp.ac.ru; mezhov@issp.ac.ru

Received November 15, 2019, published online December 27, 2019

Abstract

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 TTm = 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.

Download 1560825 byte View Contents