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Abstract This study presents the fabrication of highly photosensitive undoped zinc oxide (ZnO) thin films for vacuum ultraviolet (VUV) radiation detection, covering the wavelength range of 100–200 nm. ZnO films were deposited using hybrid pulsed reactive magnetron sputtering, assisted by ECWR (electron cyclotron wave resonance) plasma. Control of the ECWR power (PECWR), ranging from 0 to 380 W, played a crucial role in enhancing the films’ photoconductive properties. At PECWR = 200 W, the photosensitivity increased by 8 orders of magnitude compared to films deposited without ECWR assistance. This improvement was attributed to a sharp reduction in dark current due to lower defect density. Photoluminescence and cathodoluminescence spectra revealed a significant reduction in defect-related emissions for films deposited at PECWR = 200 W, confirming fewer intrinsic defects. Raman spectroscopy also showed a decrease in defect-related vibrational modes in the same films. Time-Resolved Microwave Conductivity (TRMC) measurements further supported these findings, demonstrating rapid recombination of charge carriers at 200 W, indicative of low trap densities. These results suggest that precise control of ECWR power allows for optimization of the defect concentration and crystallinity in ZnO films, paving the way for the development of high-sensitivity VUV photodetectors.

The additional operation of deaeration (compaction) of powders affects the quality of many products of chemical industries, the conditions for their delivery. Otherwise, energy consumption increases significantly. The aim of this work is the modeling of the deaeration of solid finely dispersed media in a gap with perforated hemispherical shapes on the surfaces of the shaft and conveyor belt within the framework of the mechanics of heterogeneous systems. A plane-deformation model is described, neglecting the forces of interphase interaction and taking into account the compressibility of a solid-particle-gas mixture without elastoplastic deformations. The model assumes consideration of the movement of (1) the components of the solid skeleton together with the carrying phase as a whole; (2) gas in an isothermal state through the pores of a finely dispersed material. This work is devoted to the study of part (a), i.e., behavior of the solid particle-gas system as a whole. The efficiency of the seal-deaerator is estimated using the obtained analytical dependencies for the main strength and speed indicators. The change in the degree of compaction of a spherical granule made of kaolin with given strength characteristics is investigated. It is shown that for the initial time interval up to 3.7⨯10−2 s, the growth of the porosity value relative to the horizontal coordinate along the conveyor belt is exponential and increases by a factor of 1.1. After eight such time intervals, the porosity values stabilize along the indicated coordinate with an increase of more than 1.4 times from the initial value.

The aim of this work is to develop a stochastic method for calculating the average value of the volume fraction of a key bulk component at an intermediate stage of mixing with an inclined bump based on the energy method. The specified characteristic is used to assess the quality of the granular mixture when choosing a criterion in the form of a heterogeneity coefficient of the product obtained at the corresponding stage of operation of the gravitational apparatus. This equipment is designed to produce a mixture of solid dispersed components in a ratio of 1/10 or more. At the same time, at each stage of mixing, two types of mixing devices (brush elements and inclined bump surfaces) work. A distinctive feature of the application of the energy method is to obtain an analytical relationship for the desired characteristics of the process of mixing bulk materials, taking into account their physical and mechanical properties and a set of structural and operational parameters of the apparatus. The calculation of the increment angles of reflection of rarefied flows of bulk components after interaction with the bump surface is proposed. The differential distribution functions of the number of particles of these components over the states of macrosystems are taken into account. The basis is the results of stochastic modeling of mixing of flowing media with brushes. The effectiveness of the intermediate stage of mixing with the bump using the coefficient of heterogeneity of the granular mixture is analyzed. The influence of the most significant design parameters of the gravitational apparatus and its operating modes on the quality of the intermediate mixture in comparison with the results for the initial and final steps is investigated. It has been established that this class of parameters includes the angular velocity of rotation of the drum, the angle of inclination of the bump to the horizontal, the pitch of screw winding, and a comprehensive indicator of the deformation of the brush elements. For example, an increase in the last complex indicator by 0.05 units leads to a decrease in the inhomogeneity coefficient by (0.15–0.80%) in the studied range of the angular velocity of rotation of the drums. In addition, the consequence of this is a decrease of 0.5 s−1 for the value of the angular velocity of the mixing drum, which corresponds to the minimum value for the specified quality criterion of the mixture. The latter fact allows under the selected conditions ensuring a reduction in energy costs for the expended power drives of the mixing drums. The results of the work, confirmed by experimental studies, predict rational ranges of change of significant process parameters using the criteria for the best mixing of components proposed by the authors earlier.

The purpose of the work is to develop an analytical method for calculating the effective ranges of structural parameters of the throttle part of the axial valve with the external location of the locking shell based on the proposed stochastic models of bubble formation at the initial stage of hydrodynamic cavitation. In contrast to the well-known engineering methods for choosing the conditional bore diameter for the designed control device constructed using the Pi-Buckingham theorem, this calculation method relies not only on gyrodynamic similarity criteria, but also on functional dependences for the laws of distribution of cavitation bubbles according to various characteristics (specific size bubbles, the degree of opening of the node “separator-external locking shell”). This takes into account a wide range of design and operating parameters, including the required valve capacity, as well as the physical and mechanical characteristics of the working medium. A block diagram of the calculation of the node “separator-external locking shell” for the specified axial valve is proposed. The influence of a set of design parameters for the “separator-external locking shell” assembly from the rational ranges of their variation obtained using the proposed analytical calculation algorithm on the size of cavitation bubbles is investigated. It has been established that when using the latest results in comparison with the values of parameters from irrational ranges of change, there is a tendency to reduce the ensemble average value of the diameter of the cavitation bubble by 1.95 times, when switching to a mode from 20% of the degree of separation of the separator to 80% of the opening of the throttle holes, the nominal valve capacity increases by 10.7 times. The results obtained illustrate the possibility of preventing an increase in the intensity of formation of cavities in the flow part of the control device already at the initial stage of the occurrence of cavitation.