Mode transition in radio-frequency atmospheric argon discharges with and without dielectric barriers

In this letter, basic characteristics of glow modes and their mode transition are studied for radio-frequency (rf) atmospheric argon discharges with bare and dielectrically insulated electrodes. Through input power control, large-volume rf atmospheric argon discharges with bare electrodes are achieved in the alpha mode via an abrupt transition from a constricted gamma mode, whereas dielectrically insulated electrodes result in large argon discharges in both the alpha and gamma modes with gradual mode transition. Current dependence of the 750 nm line intensity and of the gas temperature are shown to capture clearly the signature of mode transition. (c) 2007 American Institute of Physics.