Expansion of the plasma stability range in radio-frequency atmospheric-pressure glow discharges

Reliable applications of atmospheric-pressure glow discharges (APGDs) depend critically on their plasma stability. A common technique of ensuring APGD stability is to keep their operation well within their stability range by decreasing their discharge current. However, this reduces the achievable densities of the reactive plasma species and, thereby, compromises the application efficiency. In this letter, the use of high excitation frequencies in radio-frequency APGD is shown to substantially expand their stability range. It is also demonstrated that high-frequency operation introduces an added benefit of higher electron energy and greater electron density, thus enabling more abundant reactive plasma species and improved application efficiency.