Novel experiments on the heartbeat instability in complex (dusty) plasmas and hypothesis on its physical mechanism

A series of new ground-based experiments on the heartbeat instability in complex (dusty) plasmas was conducted. The experiments included the investigation of a stability diagram of a dust cloud in a RF discharge, time-resolved measurement of the plasma emission during the heartbeat instability, control of the instability by means of a modulated laser beam, whose wavelength was tuned to an atomic transition of a working gas. As an outcome of the experiments, a hypothesis on the physical mechanism generating the heartbeat instability was suggested. According to this hypothesis, the instability occurs due to the periodically repeated formation of the sheath on the boundary between the microparticle-free area (void) and the complex plasma. The origin of this transformation is the loss of the plasma on microparticles surrounding the void. We have shown that this hypothesis is consistent with all the available experimental data on the heartbeat instability.