Based on measurements of nonlinear second-sound resonances in a high-quality resonator, we have observed a steady-state wave energy cascade in He II involving a flux of energy through the spectral range towards high frequencies. We show that the energy balance in the wave system is nonlocal in K space and that the frequency scales of energy pumping and dissipation are widely separated. The wave amplitude distribution follows a power law over a wide range of frequencies. Numerical computations yield results in agreement with the experimental observations. We suggest that second-sound cascades of this kind may be useful for model studies of acoustic turbulence.
First observation of a steady-state wave energy cascade for second sound in a high-Q resonator, opened the way for a major programme on wave turbulence and discovery of inverse cascade. McClintock was PI on the grant, guided the experiments, and wrote most of the paper. RAE_import_type : Journal article RAE_uoa_type : Physics