Nonlinear dynamics of a harmonically forced double layer in a discharge plasma

A strong anode type double layer is created in the target chamber of the do uble plasma machine and some of its dynamical features are studied experime ntally. When the fireball is created and the separation grid of the double plasma machine is floating very coherent oscillations of plasma potential a nd density are excited. These oscillations also have very high amplitude. W hen the floating potential of the separation grid is harmonically modulated by an external signal, periodic pulling, synchronization and period doubli ng bifurcations of the plasma oscillations are observed. Some of those phen omena can be explained by the model of a harmonically forced van der Pol os cillator.