Apparatus and tuning method for mitigating RF load impedance variations due to periodic disturbances

A controller for a radio frequency generator comprising:

• a RF power controller coupled to a RF power source, the RF power controller configured to generate a control signal to vary an RF output signal from the RF power source, the RF power controller configured to adjust at least one parameter that determines a characteristic of the RF output signal in response to a synchronization signal,
• wherein the parameter is perturbed in accordance with a hopping pattern, and the parameter is adjusted in accordance with one of minimizing or maximizing a cost function responsive to perturbation of the at least one parameter by the hopping pattern, and
• wherein the hopping pattern may be adjusted by applying one of an offset or a scaling factor to the hopping pattern.