Plasma stability control using dielectric barriers in radio-frequency atmospheric pressure glow discharges

Abstract

It is widely accepted that electrode insulation is unnecessary for generating radio-frequency (rf) atmospheric pressure glow discharges (APGDs). It is also known that rf APGDs with large discharge current are susceptible to the glow-to-arc transition. In this letter, a computational study is presented to demonstrate that dielectric barriers provide an effective control over unlimited current growth and allow rf APGDs to be operated at very high current densities with little danger of the glow-to-arc transition. Characteristics of electrode sheaths are used to show that the stability control is achieved by forcing the plasma-containing electrode unit to acquire positive differential conductivity.

Mitigating plasma constriction using dielectric barriers in radio-frequency atmospheric pressure glow discharges

“…Both the discharge current and the applied voltage are predominately sinusoidal, with the current leading the voltage by a phase shift of less than 90°. Their wave forms are consistent with the simulation results 12 and similar to those found in rf APGD with bare electrodes. 3,8 In contrast, their sinusoidal character is distinctly different from the pulselike current wave form of conventional kilohertz atmospheric DBD.…”

“…12 This technique could potentially be used to control plasma constriction in rf APGD. In this letter, we present an experimental study to demonstrate that dielectric barriers can mitigate plasma constriction in rf atmospheric glow discharges, thus allowing for stable plasma operation at large discharge currents.…”

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

“…11 For both atmospheric argon discharges, the applied voltage undergoes a large reduction of more than 660 V immediately after the breakdown, distinctly different from rf glow discharges in atmospheric helium. 10,11 Subsequently, the Ar rf APGD evolved directly into a constricted plasma column of about 1 mm in diameter at point B in Fig. 1͑a͒ image not shown͒ and further increase in the input rf power was found to be incapable of evolving the constricted plasma into a large-volume homogenous discharge.…”

“…9 Recently, dielectric insulation of electrodes is also found beneficial. 10,11 By increasing the power input after gas breakdown, dielectrically insulated electrodes lead to largearea homogenous Ar APGD, whereas bare electrodes tend to evolve the argon discharge directly into constricted plasma. However, little is known of the underpinning physics.…”

Atmospheric glow discharges from the high-frequency to very high-frequency bands

“…10 One technique to achieve high plasma density without plasma constriction is to add a dielectric barrier to the electrodes so as to control the growth of the discharge current. [11][12][13] Its drawbacks are, however, an increase in the breakdown voltage and a possible drift in plasma properties when plasma chemistry is harsh and contaminates the dielectric material. Instead of modifying physical structure of the electrodes such as using dielectric barriers, it is possible to facilitate temporal modification of plasma dynamics, for example, by changing the excitation frequency.…”