Microstreamer expansion and toxic gas remediation efficiency in dielectric barrier discharges

Summary form only given. Dielectric barrier discharges (DBD) are being investigated as plasma sources for remediation of toxic gases such as N/sub x/O/sub y/ (oxides of nitrogen) and volatile organic compounds. Typically, DBDs are composed of parallel electrodes with a 2-5 mm gap. One or both electrodes are covered by a dielectric. By applying a potential of several kV with a frequency of a few hundreds to several kHz, a plasma of filamentary microdischarges is created. The efficiency of plasma remediation depends on the efficiency of generating the oxidizing or reducing radicals. This efficiency is in turn related to microstreamer initiation and expansion, which depend on the physical parameters of the device, such as the thickness of the dielectric and format of the voltage pulse. For example, efficiency of the remediation of N/sub x/O/sub y/ is largely dependent on the efficiency of generating N atoms by electron impact, which in turn reduce NO (N+NO/spl rarr/N/sub 2/+O). We have developed 1-d and 2-d plasma chemistry and hydrodynamic models to investigate the efficiency of generating radicals in DBDs. These simulations include circuit models, solution of Boltzmann´s equation for the electron energy distribution, plasma chemistry modules, and solution of the compressible Navier Stokes equations. Results from these models will be discussed for the efficiency of radical generation for N/sub x/O/sub y/ remediation from microstreamers in humid air as a function of circuit parameters (pulse width, voltage) and dielectric properties. Due to charging of the dielectric, the maximum temperature rise of the microstreamer is a weak function of the voltage pulse width.