AVS 51st International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS2-MoA

Invited Paper PS2-MoA1
Dielectric Barrier, Atmospheric Pressure Glow Discharges (DB-APGD) : Applications, Diagnostics and Modeling

Monday, November 15, 2004, 2:00 pm, Room 213B

Session: Emerging Plasma Applications
Presenter: M.R. Wertheimer, Ecole Polytechnique de Montreal, Canada
Authors: M.R. Wertheimer, Ecole Polytechnique de Montreal, Canada
I. Radu, Ecole Polytechnique de Montreal, Canada
R. Bartnikas, Hydro Quebec Research Institute, Canada
Correspondent: Click to Email
The field of "cold" (non-equilibrium) plasmas at atmospheric pressure (AP) is receiving much attention, in part due to the reward of more economic processing without vacuum systems. Dielectric barrier discharges (DBD) are a particularly promising subgroup; among these, AP glow discharges (APGD) occur in certain gases with long-lived energetic states, for example in N@sub2@ and in the noble gases. They manifest several remarkable peculiarities, described below, and they have opened application areas as diverse as (a) polymer surface modification, (b) deposition of novel thin film materials, (c) short wavelength light sources for photochemistry, (d) plasma displays, and numerous others. The presentation commences with a short overview of these recent industrial innovations; we then describe fundamental and applied research on DB-APGD in this laboratory. In the former category, diagnostic and modeling studies in helium are briefly presented : (i) At low applied a.c. voltage, V, a single, multi-µs current pulse per half-cycle occurs, but the "glow" may comprise many geometrically-ordered plasma columns which ignite and extinguish in perfect synchronism; (ii) at higher V, these merge into a "true" APGD, spread uniformly over the entire electrode area. (iii) Under specific conditions of V and the a.c. frequency, f, a "pseudoglow" regime sets in, comprising two or more pulses of monotonically decreasing amplitudes per half-cycle. We explain observations (i) to (iii) and demonstrate excellent agreement between experimental measurements (e.g. spatial and temporal evolution of the discharges) and the two-dimensional theoretical model developed by Novak and Bartnikas. Finally, turning to applied research, the unique capabilities of DB-APGD processing of materials is illustrated with several examples drawn from categories (a), (b) and (c) identified above.