Quantum and quasiclassical types of superfluid turbulence

By injecting negative ions in superfluid He4 in the zero-temperature limit (T≤0.5K), we have generated tangles of quantized vortex line with negligible large-scale flow. For this quantum regime of superfluid turbulence, the vortex line length L was found to decay at late time t as Lât-1, the prefactor being independent of the initial value of L. The corresponding effective kinematic viscosity is 0.1 κ, where κ is the circulation quantum. At T>0.7K, a jet of ions generates quasiclassical tangles identical to those produced by mechanical means. © 2008 The American Physical Society.