Observations of Quasiperiodic Transition to Frequency Locking in Electron Cyclotron Resonance Plasma

The temporal evolution of plasma oscillations as microwave power changes is analyzed in an electron cyclotron resonance plasma. A first frequency f1 appears at an input microwave power Pi=600 W , then at Pi=650 W a second frequency f2 , much smaller, is observed. Their combination frequencies f=n1f1+n2f2 (n1 and n2 are integers) and quasiperiodic states are also exhibited at 690 W . By increasing power up to 710 W , frequency locking occurs with a frequency ratio f1/f2=20/3 . Bifurcation of period2 in the frequency-locking window is also observed. copyright 1997 The American Physical Society