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Modelling of a N 2 –O 2 flowing afterglow for plasma sterilization

2005; Institute of Physics; Volume: 38; Issue: 3 Linguagem: Inglês

10.1088/0022-3727/38/3/011

1361-6463

C. D. Pintassilgo, J Loureiro, Vasco Guerra,

Surface Modification and Superhydrophobicity

A kinetic model for a flowing microwave discharge in N2–O2 at ω/(2π)= 2450 and 915 MHz, in the pressure range p = 1–10 Torr, is constructed with the purpose of studying the conditions that maximize the concentrations of NO(B 2 � ) molecules and O( 3 P) atoms, which are known to play a central role in the sterilization processes. The former are responsible for the emission of UV photons associated with the NOβ bands. The NO(B) concentration is found to pass through a maximum, at approximately 1–3% of O2 added to the mixture, which is in good agreement with the measured maximum of UV emission intensity, and with the shortest time required for the inactivation of spores. For such an O2 percentage, the NO(B) also remains in the afterglow, with only a small reduction, up to a few ∼100 ms. Furthermore, the NO(B) concentration peaks with increasing pressure, with the corresponding maximum shifted to lower O2 percentages, in agreement with the observations of UV intensity. The concentration of O( 3 P) atoms is practically unchanged along the afterglow, at least up to times as high as 100 ms.