Weld Right, Inc. has its certified welder, Jake Garvin, in the field using a DC arc Welder. As typical for the DC machine, Jake finds that the arc is wandering from his pre-determined weld time. This wandering is known as?

Weld Right, Inc. has its certified welder, Jake Garvin, in the field using a DC arc Welder. As typical for the DC machine, Jake finds that the arc is wandering from his pre-determined weld time. This wandering is known as?