Turbulence in an Auto-Oscillating Complex Plasma

We present an experiment on the development of turbulence in a microparticle cloud in a low-temperature plasma laboratory onboard the International Space Station. First, the complex plasma cloud was stabilized with an alternating electric field. Once the stabilization was switched OFF, a so-called heartbeat instability developed in which the microparticles are oscillating radially. We show that the kinetic energy spectra develop a double cascade once the cloud becomes unstable. A double cascade has been predicted by Kraichnan and Leith for forced 2-D turbulence, but has only seldomly been observed in experiments. We also show that the reduced rates of energy and enstrophy transfer can be used to infer the excitation wavenumber k_{\text {exc}} , in good agreement with k_{\text {exc}} obtained from the energy spectrum.