Chaos control of fluctuations caused by flute instability in electron cyclotron resonance plasma

Controlling chaos of density fluctuations observed in electron cyclotron resonance (ECR) plasma is carried out using the time-delayed auto synchronization (TDAS) method introduced by Pyragas. Since the TDAS method, which is a sort of feedback system, requires a feedback signal, the input power of microwaves for ECR discharge is modulated by signals of frequency (<30 kHz) based on the ion-saturation current indicating the electron density. Fluctuations caused by the flute instability reach the chaotic state when the microwave power is increased. It was found that when the TDAS method is applied to the chaotic state, the chaotic state transitions to the periodic state and the correlation dimension changes from a non integer value to an integer value. (author)