Second sound induced relief on the surface of superfluid helium, its loss of stability and the transition from quasiperiodicity to turbulence

Abstract

The relief created on the surface of liquid helium by standing waves of second sound of low intensity has been shown to be stable and to have negligible motion. Above a critical second sound intensity it looses its stability and begins to oscillate. Energy from the second sound is transferred to the gravity wave system. Gradually the surface reorganizes into a new stable surface pattern showing an oscillation with a basic frequency circa 10 -2 times the second-sound frequency and up to forty superharmonics. At higher second-sound excitations the patterns even start to rotate. The transition from quasiperiodic motion with three frequencies to turbulence is described.