The low pressure RF discharges have found a wide application in plasma technologies for processing solid material surfaces. Recent measurements indicate that the performance of these discharges can be modified by the use of an extra auxiliary RF (dual-frequency discharge) or DC (RF/DC discharge) power source applied to the reactor electrodes. In this paper the superposition of RF and DC voltages in two-electrode capacitive discharges and their applications for surface treatment and sterilization of medical devices are numerically investigated and dependencies of key plasma parameters on a reactor configurations are studied.

The discharge has been formed inside a tube, 5.5 cm in diameter and 4cm long. The two-dimensional (2D) self-consistent drift-diffusion fluid model is developed to describe the charged particle transport. The two-term Boltzmann approximation is used for calculating electron kinetic coefficients for the model. Axial and radial profiles of charged particles density, average energy of electrons, electric field and other parameters are obtained. The ion energy at the processed product and hence the surface temperature of the latter is evaluated. Numerical results are in a good agreement with experimental ones. Advantages of dual frequency RF and RF/DC discharges versus RF capacitive discharges for the sterilization of medical products are shown.