Methods, systems, and computer program products are described for measuring and controlling parameters of a plasma generator. A current in a primary winding of a transformer or inductive element that generates a plasma is measured. A voltage across a secondary winding of the transformer or inductive element is measured. Based on the current of the primary winding and the voltage across the secondary winding, a parameter of the plasma is determined. The parameter includes a resistance value associated with the plasma, a power value associated with the plasma, or both.