Publications

Abstract: Electrical properties of the thin films of poly(arylene ether ketone) copolymers (co-PAEKs) with the fraction of phthalide-containing units of 3, 5 and 50 mol% in the main chain were investigated by using radiation induced conductivity (RIC) measurements. Transient current signals and current-voltage (I-V) characteristics were obtained under exposing 20÷25 thick films of the co-PAEKs to monoenergetic electron pulses of the energy ranged from 3 to 50 keV in the electric field ranged from 5 to 40 V/μm. The Rose-Fowler-Vaisberg semi-empirical model based on a multiple trapping formalism was used for an analysis of the RIC data and the parameters of the highly dispersive charge carrier transport were evaluated. The analysis revealed that charge carriers moved in isolation from each other and the applied electric fields were below the threshold field triggering the switching effect (a reversible high-to-low resistivity transition) in the co-PAEK films. It was also found that the co-PAEK films due to the super-linear I-V characteristics are highly resistant to electrostatic discharges arising from the effects of ionizing radiation. This property is important for the development of protective coatings for electronic devices.

Abstract: We have performed comparative numerical calculations using a multiple trapping (MT) formalism with an exponential and an aggregate two-exponential trap distributions for describing two mostly used experimental setups for studying the radiation-induced conductivity (RIC) and the time-of-flight (TOF) effects. Computations have been done for pulsed and long-time electron-beam irradiations in a small-signal regime. Predictions of these two approaches differ appreciably in both setups. The classical MT approach proved very popular in photoconductive polymers generally and in molecularly doped polymers in particular, while a newly proposed complex MT worked well in common polymers. It has been shown that the complex MT successfully accounts for the presence of inherent deep traps, which may or may not have an energy distribution.

Abstract—We have  performed computer simulations and experimental studies of characteristics of a standard analog device—the heterodyne employing a printed circuit board (PCB)  made from a composite dielectric with a controlled dark conductivity. Simulation results show that an increased conductivity of the PCB smaller than 2 × 10^−7 Ohm^−1 · m^−1 has almost no effect  on the operating characteristics of a heterodyne operating in the frequency range of 9–37 MHz, which are in a good agreement with the experimental data. Such PCBs are expected to exclude  electrostatic discharges in spacecraft electronic devices otherwise  occurring in them due to their internal charging by the ambient  space plasma.

The primary purpose of this paper is to provide an overview of existing education solutions for IoT and develop proposals for their improvement. The study draws analysis of current conditions of the educational IoT sphere, a comparative analysis of educational products used for teaching of undergraduate students. With that the article describes the architecture of our own software and hardware platform for learning IOT. Moreover, this paper reviews methods and technical instruments employed to design software and hardware appliances.

Computer simulations of electrostatic discharges (ESD) effect on high-power MOSFET-transistors with built-in  protection  have  been  carried  out.  It  was  found  that  the transistors with low gate-source capacitance are more sensitive to the ESD effect.The  dependence  between  printed  circuit  board  (PCB)  capacity,  causing  breakdown  of  MOSFET-transistor  gate dielectric, and ESD voltage was established.  It  is  shown  that  for  transistor  haying  low  gate-source capacitance,  the  existence  of  the  built-in  protection  does  not prevent gate dielectric breakdown at electrostatic discharges.  It is recommended to provide external ESD protection for high-power  MOSFET-transistors  with  built-in  protection having low gate-source capacitance, for example, having turned on the ESD protection diode in the electric circuit. 

ABSTRACT: An analytic model based on the transport level and effective temperature concepts has been developed to describe consistently both the quasi- and nonequilibrium transport regimes in nonpolar organic solids with the Gaussian uncorrelated energetic disorder. Field and temperature dependences of drift mobility on the nonequilibrium transport regime relating to the time-of-flight experiment are in good agreement with the Monte-Carlo simulation results in a broad range of fields and temperatures using the same set of model parameters for both transport regimes.

We have investigated the radiation-induced conductivity (RIC) in Kapton-like polymers in which it increases with an accumulating dose at large dose rates and long irradiation times. Such a behavior is very useful for spacecraft applications as it allows mitigating the spacecraft charging problems. Also, we studied ordinary polymers whose RIC steadily falls after reaching an initial maximum. To interpret experimental results, we used the semi-empirical Rose–Fowler–Vaisberg model. Numerical and experimental results have been compared with published data.

We have investigated radiation-induced conductivity (RIC) in several low mobility common polymers as well as two with excellent charge transport characteristics. Irradiations were pulsed and continuous with constant dose rates from microseconds to seconds. Experiments were done in the small-signal mode at a relatively high electric field. To interpret the results, we performed numerical calculations based on the conventional as well as the modified Rose-Fowler-Vaisberg (RFV) models. Also, to accommodate the time-of-flight and deep trapping effects, we used an analytic formula describing strongly nonequilibrium dispersive transport at high electric fields in the presence of deep trapping. As a result, several long-standing RIC issues have been resolved. A crucial role of pulsed irradiations for polymer parameterization in terms of the RFV model has been demonstrated.

Abstract—We have simulated an electron bulk charging of the plastic cases of electronic devices as an integral part of the spacecraft internal charging problem. The semiconductor crystal has been placed inside a spherical shell of a polymer dielectric 10^−3–10^−2 m thick having an intrinsic (dark) conductivity in the range from 10^−16 to 10^−9 Ohm ^−1 ·m^−1. The crystal itself is a parallelepiped with sharp edges and vertices which substantially reduce an electrical strength of the case polymer. To assess this effect, we studied the field enhancement at the electrode as a function of its radius of curvature by measuring the reduction of the breakdown strength of air in a similar onfiguration for electrode radii 2 × 10^−5–10−^ m.

The influence of diffusion on the current shape in the time-of-flight (TOF) experiment under conditions of the quasiequilibrium transport has been considered. An analytical expression for the transient current density has been obtained for the case of the reflecting front electrode. The expression has been found to be in a better agreement with the Monte-Carlo numerical modeling than the usual expression based on the standard convection–diffusion equation. We found an estimate of the minimum layer thickness for a flat plateau appearance on TOF current transients.

Abstract: Polymer dielectrics subjected to intense radiation fluxes exhibit a radiation-induced conductivity (RIC). Polyimide is a good dielectric with excellent mechanical and thermal properties featuring high radiation resistance currently widely used in the spacecraft industry. Its RIC has been extensively studied in several laboratories. The purpose of the present study is to make a direct measurement of the RIC for both pulsed and continuous irradiation using a current sensing technique, which is contrary to the indirect method employing a surface-potential decay technique that is now preferred by spacecraft charging engineers. Our experiments are done in a small-signal regime excluding any recombination and dose eects. In combination with existing computer codes, we managed to develop further the conventional multiple trapping formalism and the RIC theory based on it. The main idea is to supplement an exponential trap distribution responsible for a dominant dispersive carrier transport in polymers with a small concentration of inherent deep traps which may or may not have an energy distribution. In line with this reasoning, we propose a tentative set of RIC model parameters for polyimide that accounts for the observed experimental data. The findings and their implications are discussed in a broad context of previous studies.

The paper presents the analysis of the signal integrity in microstrip transmission line with nanoconducting dielectric. It shows the results of calculating the passage of a sequence of pulses of trapezoidal shape to account for losses in copper. It is due to its finite conductivity and skin effect, which significantly affects the high frequency harmonics, and also to the loss in nanoconducting dielectric with a high end-to-end conductivity. It is shown that all these losses are small and the use of nanoconducting dielectrics for eliminating electrostatic discharge is justified.

Computer simulations and experimental investigation for characteristics of the standard analog device – the heterodyne executed on the printed circuit board with replacement insulators from the composite dielectric having controlled dark conductivity have been carried out. Results of simulation showed that increase in conductivity of material of the printed circuit board (PCB) up to 2·10-7 Ω-1 ·m-1 practically does not change operating characteristics of a heterodyne in the range of the frequencies of 9 - 37 MHz. Simulation results are in good agreement with experimental data. Possibility of their effective use in space application devices, which prevents emergence of electrostatic discharges it, has been shown.

The issue give a possible solution of the problems concern mathematical and computer simulation of radiation electrization of composite dielectric polymer films with controlled conductivity, capable of providing a drain of a charge accumulating under the action of cosmic plasma is reveal. Models and theoretical approaches were considered to calculate the electrization of polymer films, which are irradiated with ionizing radiation with different dose rates. A physic-mathematical model of radiation electrization of composite dielectric polymer films with controlled conductivity was proposed, taking into account the time-varying value of its radiative conductivity. It is shown that when the radiation conductivity is commensurable with the dark conductivity, it substantially slows down the increase of the electric field strength at radiation electrization.

We have performed numerical analysis of the charge carrier transport in a specific molecularly doped polymer using the multiple trapping model. The computations covered a wide range of applied electric fields, temperatures and most importantly, of the initial energies of photo injected one-sign carriers (in our case, holes). Special attention has been given to comparison of time of flight curves measured by the photo-injection and radiation-induced techniques which has led to a problematic situation concerning an interpretation of the experimental data. Computational results have been compared with both analytical and experimental results available in literature.

Currently, Russia conducts various works aimed at mitigating spacecraft charging effects interfering with the operation of the on-board electronics. We will inform you about the progress in developing the discharge-free near- Earth satellites. Also, we will report on participation of our specialists in preparing international guidance documents on the problem of spacecraft charging. A part of this paper will cover spacecraft activities investigating geomagnetic and radiation conditions on near-Earth orbits

In operation results of computer simulation of characteristics of the standard analog device - the heterodyne executed on the printed circuit board from the composite dielectric having feeble conductivity are explained. Results of simulation showed that increase in specific bulk conductivity of material of the printed circuit board to 2·10 -7 Ohm -1 -m -1 practically does not change operating characteristics of a heterodyne. The possibility of effective use of the composite poorly carrying out dielectrics in standard radio engineering devices allowing to prevent origin of electrostatic discharges is set.