Chitosan–hydroxyapatite composite layers were deposited on Si substrates in radio frequency magnetron sputtering discharges. The plasma parameters calculated from the current–voltage radio frequency-compensated Langmuir probe characteristics indicate a huge difference between the electron temperature in the plasma and at the sample holder. These findings aid in the understanding of the coagulation pattern of hydroxyapatite–chitosan macromolecules on the substrate surface. An increase in the sizes of the spherical-shape grain-like structures formed on the coating surface with the plasma electron number density was observed. The link between the chemical composition of the chitosan–hydroxyapatite composite film and the species sputtered from the target or produced by excitation/ionization mechanisms in the plasma was determined on the basis of X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and residual gas mass spectrometry analysis.

A cold plasma source operating at atmospheric pressure powered by a voltage multiplier is reported. In addition to its usual high voltage output, there is an intermediate output of lower voltage and higher current capability. A discharge current is drawn from both outputs. The ratio of the current supplied by each output depends on the operating state, namely, before or after the plasma jet formation. The electrical circuit is equivalent to two dc sources connected in parallel, used to initiate and sustain the electrical discharge. The plasma source is aimed to study the effect of cold plasma on the surface of various liquid or solid materials, including polymers.

The oscillations period increase of a discharge tube relaxation oscillator placed in a low intensity microwave field is reported. The experimental setup consists of a miniature neon lamp inserted into a relaxation oscillator circuit. The microwave field is generated using a low power transmitter operating at 2.412 GHz. The average period of the relaxation oscillations as a function of the dc supply voltage has been measured in two cases, namely, in the presence of microwave field and in the absence of the microwave field, respectively. The oscillation period has been measured as the time interval between two consecutive flashes produced by the neon lamp and observed using a photocell. The maximum relative variation of the oscillations period due to the microwave field was about 13% at 10 mW transmission power. This effect can be used to detect the microwave fields. A similar principle has been described to detect the optogalvanic effect. Variation of the breakdown voltage and minimum voltage necessary to maintain the discharge as an effect of the microwave field is discussed.

A novel system aiming to electrically supply various cold plasma generators is proposed. It operates as a programmable linear current source which is able to maintain a dc constant discharge current at various discharge voltages required to sustain the plasma jet. Its design is based on a specific electronic device called a switchable current regulator, which considerably simplifies the circuit topology. Experimental results carried out in real operating conditions confirm the practical purpose of the proposed solution.