Eighty years have passed since Langmuir's first use of the word 'plasma' for describing ionized media. On this occasion we would like to present selected recent results on the application of Langmuir probes to diagnose plasma jet systems. To demonstrate the versatility of the Langmuir probe method we give examples of measurements of the spatial distribution of the plasma parameters as well as their temporal dependence in cases when the plasma jet system operates in a pulsed regime. A part of this paper is devoted to introducing the Langmuir probe technique, especially with regard to its application under conditions when collisions between the charged and neutral particles in the probe sheath cannot be neglected and when the electron energy distribution function in plasma cannot be approximated by a Maxwellian one. In the experimental part we present Langmuir probe measurement of low-pressure and atmospheric-pressure plasma jet systems that are currently used for experiments with deposition of materials with special properties.Most of the experimental results presented in this paper are original data. However, in order to fill in the picture we have used in the case of a barrier-torch discharge three figures that have already been published.

The properties of thin thermoelectric layers (about 60 nm in thickness) prepared by pulsed laser deposition are presented. Hot pressed targets were made from “middle” temperature range thermoelectric bulk materials with the potential high figure of merit ZT. P-type and N-type layers were prepared from Yb0.19Co4Sb12 and Ce0.1Fe0.7Co3.3Sb12 targets, respectively. The thin films were deposited on quartz glass substrates using KrF excimer laser. The individual layers were prepared by applying different laser beam energy densities (2 or 3 J cm−2) at several substrate temperatures (200, 250, or 300 °C). Crystallinity and composition of the layers were examined by x-ray diffraction and wavelength dispersive analysis, respectively. Homogeneity of Yb across a surface of the Yb filled film was explored by secondary ion mass spectrometry. The thermoelectric properties, the Seebeck coefficient, the electrical resistivity, and the power factor, for the best prepared P and N layer are presented in the temperature range from 300 to 500 K.

DC energized hollow cathode plasma jet system was examined by radially movable Langmuir probe. Radial distribution of electron concentration, plasma and floating potentials and mean electron energy were obtained from measured probe characteristics at the distance 17 mm downstream of the hollow cathode -nozzle. The radial dependence of plasma parameters was measured for distances from the system axis 0-120 mm in the discharge containing Ar and O2. Two scenarios were used: addition of O2 into the nozzle and into the plasma vessel. The differences in measured floating and plasma potential, electron density and mean electron energy radial courses obtained in the two scenarios are qualitatively explained. In addition temporal dependences of main plasma parameters for discharges in clean argon and argon-oxygen mixture were investigated that demonstrate system stability and its applicability for deposition of layers containing Ti. TiOx thin films were deposited onto glass substrates and examined by AFM and ellipsometry. It is illustrated that the differences in plasma parameters in the two scenarios of oxygen addition influence the layer properties.

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A spin-coating method was applied for the first time to prepare a colloid monolayer on the optical crossed gratings used as a template. Four polystyrene colloids of various nominal sizes and different surface charges were spin-coated on templates with periods matched to the particles size. Three types of coverage were described depending on the spin-coating parameters and particles type. The optimal coverage was obtained for all four particles sizes. A way of finding the right spin-coating parameters was proposed. The analysis of a coverage capability of polystyrene particles showed that neutral particles have the highest ability to order on the templates used. Large monolayered areas of ordered particles were used as a lithographic mask for generating a pattern of gold nanoparticles with a square symmetry. A few hundred square micrometers large, continuous and fully defect-free areas of gold nanoparticles were produced on the nearly entire surface of the templated substrates.