Observation of bifurcation phenomena in an electron beam plasma system

Bifurcation phenomena are experimentally observed in an electron beam plasma system using a double plasma device. When an electron beam is injected into the target plasma, an unstable wave and the subharmonics of period 2, period 3, and period 4 are observed. The fundamental unstable wave is specified to be a beam mode wave excited by an electron beam plasma instability. It is confirmed that these bifurcation phenomena originate from nonlinearity of the unstable wave. The correlation dimensions and Lyapunov exponents indicate that the system becomes chaotic when the subharmonics of period 3 or period 4 appear.