The paper discusses the wave-plasma energy coupling in cylindrical microwave discharges produced in argon, operating at frequency 2.45 GHz, average electron densities between 5×1011−3×1012 cm−3 and pressures from 10−3 to a few torr. The study focus on a special propagation mode called surface wave (SW), whose field distribution presents a maximum intensity near the discharge wall. Moreover, the influence of the space-charge sheath in the discharge energy deposition is carefully analysed. Simulation results show that the absorption of energy from the SW occurs in two different modes (convection and friction) depending on pressure, and that the transition between them is observed around 10 mtorr pressure, regardless of the electron density. The paper proposes a definition for the discharge yield, which can be of interest in optimizing the operation conditions of gas discharges for applications.

Recently, plasmas have been largely studied to develop a new cold and safe sterilization process. The plasma efficiency on bacteria destruction has been proved at low or near atmospheric pressure. In our investigation we used a N2-O2 post discharge at low pressure, where the experimental conditions allowing the optimal production of active species have been determined: 100 Watt, 1 Ln.min−1, 5 Torr. By exposing E. coli to these plasma conditions, it is demonstrated a synergy of N and O active atoms on substrate temperature: a reduction of 6 log was achieved after a treatment time of 20 minutes at 80 °C and of 12 log after 5 minutes at 120 °C.

A N2 direct current discharge was studied by optical emission spectroscopy. Experimental parameters as gas flow rate (Q), pressure (p) and current (I) were varied independently, covering the following range: 10 < I < 75 mA, 100 < Q < 1000 sccm and 1.7 < p < 10 torr, corresponding to the following plasma parameters: electron density in the range 109−1012 cm−3 and reduced electric field between 3×10−16 and 10−15 V cm−2. The N2(C $^{3}{\rm \Pi} _{\rm u},\,v'$), N2(X $^{1}{\rm \Sigma} ^{+}_{\rm g}, \,v$) vibrational temperatures and the gas temperature were obtained from the first and second positive systems emissions. The N2(C $^{3}{\rm \Pi} _{\rm u},\,v'$) vibrational distributions did not exhibit a Boltzmann character. A linearization process was employed to such distributions allowing us to calculate the N2(C $^{3}{\rm \Pi} _{\rm u},\,v'$) temperature. The N2(X $^{1}{\rm \Sigma} ^{+}_{\rm g},\,v$) temperature was calculated from the N2(C $^{3}{\rm \Pi} _{\rm u},\,v'$) one on the basis of the Franck-Condon factors. Results and the method of vibrational temperature calculus are presented.

The synthesis of low density polyethylene (LDPE) ultrahydrophobic surfaces with controlled roughness and transparency was described in a two steps O2 and CF4 plasmas treatment. Water contact angle as high as 171°, contact angle hysteresis less than 4°, and sliding angle as 4° were obtained on those surfaces. The surfaces with small roughness reached 85% of transparency between 400 nm and 800 nm of wavelength. Besides the dynamic dewetting experiments showed a particular behavior. While they were wet with water, the surfaces loosed their ultrahydrophobic properties. An explanation of this behavior was given according to both Wenzel and Cassie Baxter wetting states.

A new technical approach of a traditional method for the rapid (and therefore, non interfering) determination of the thermophysical properties of porous materials likely, a priori, to undergo coupled heat and moisture transfers is described. The improvements discussed here consist in the use of a heater film suiting the “method of the hot plane film” especially well. A comparison with former works by one of the method's author is made. Finally, the updated method is applied to a variety of particularly significant materials.

A durable water repellent, stain resistant or flame retardant character can be conferred to polyacrylonitrile (PAN) textiles by using the plasma induced graft polymerization technique. The monomers used are perfluoroalkylacrylate, (meth)acrylate phosphates, and phosphonates which are well known to be effective for the waterproofing and the fireproofing of polymeric substrates, respectively.

Results are presented on the production of oxygen atoms in flowing microwave post-discharges in a reactor of 5 litres at high pressures (10-50 torr). Diagnostics of O-atom densities are obtained by NO titration in the post-discharge. An hydrodynamic and kinetic model has been developed to obtain the spatial distribution of O-atoms inside the post-discharge reactor. Such post-discharge processes at high pressures are of interest for elastomer treatments.

Flowing post-discharges resulting from surfatron microwave discharges in nitrogen and methane gas mixture with low amount of methane (less than 1%) are implemented for nitrocarburising treatment. Atomic nitrogen and atomic carbon densities are measured in post-discharge by combining optical emission spectroscopy and NO titration. The kinetic schema leading to N and C atoms densities is presented with a special attention paid to the effect of gas temperature on the kinetic constants. The influence of different discharge parameters such as methane percentage, total pressure, methane injection upstream or downstream the discharge and gas temperature are studied by these techniques. It is shown that, except at the lowest percentage used in this study (0.02%), methane introduction decreases nitrogen atoms densities. A maximum in carbon atoms density (1013 cm−3) is found for 0.05% of methane introduced in a nitrogen discharge at 2670 Pa. The corresponding nitrogen atoms density is two orders of magnitude higher (2–3 × 1015 cm−3). We present some arguments showing that gas expansion is the only effect that gas temperature has on nitrogen atoms densities. At present, it is not clear if such explanation is also applicable to the effect of gas temperature on carbon atoms densities.