A method of conditioning internal surfaces of a plasma source includes flowing first source gases into a plasma generation cavity of the plasma source that is enclosed at least in part by the internal surfaces. Upon transmitting power into the plasma generation cavity, the first source gases ignite to form a first plasma, producing first plasma products, portions of which adhere to the internal surfaces. The method further includes flowing the first plasma products out of the plasma generation cavity toward a process chamber where a workpiece is processed by the first plasma products, flowing second source gases into the plasma generation cavity. Upon transmitting power into the plasma generation cavity, the second source gases ignite to form a second plasma, producing second plasma products that at least partially remove the portions of the first plasma products from the internal surfaces.