I. Introduction
Nonequilibrium plasmas at atmospheric pressure have attracted considerable attention because of their significant potential applications in a wide range of industrial fields [1]. A gliding arc discharge is one of the methods to generate a nonequilibrium plasma at atmospheric pressure [2]. In a gliding arc discharge, the discharge is first ignited at the shortest gap between two diverging electrodes. Then, the discharge channel is moved along the electrodes by the buoyant force and the gas drag force. The gliding arc discharge propagates upward until the power of the source is not sufficient to sustain the discharge. Subsequently, a new gliding arc discharge is reignited at the shortest gap between the electrodes.