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The article is devoted to the development and research of a supercapacitor based on an aqueous electrolyte. The review of the current state in the field of energy storage is carried out. The processes occurring in the supercapacitor are considered. Sheets of paper with different carbon concentrations have been created. The design of the housing has been developed with the possibility of replacing the plates and electrolyte. This is an advantage in the process of conducting experiments. According to the results of the study, a prototype supercapacitor based on NaCl electrolyte with a capacity of 9F and a maximum output voltage of 1.2 V is presented.

The article is devoted to the measurement of the ion beam velocity of an accelerator two-gap ion thruster. A theoretical representation of the physical process of capturing charged particles using a cylindrical sensing element is given. A schematic diagram and a printed circuit board for detecting an accelerated ion beam have been developed. The expression for calculating the signal current of the sensing element is defined. A condition for capturing charged particles using the critical mobility of charges is formulated.

This paper presents the results of experimental studies of 15 design versions of capacitive and induction type microwave antennas. As part of the work on the development of an accelerator ion thruster, 32 radiator designs were studied. The research was carried out in order to select the optimal design of a plasma-generating microwave antenna for installation in the discharge chamber of a prototype ion thruster. The volt-ampere characteristics (VAC) were obtained the microwave generator when working with each design of the radiator in a vacuum chamber. The VAC is obtained in the presence and absence of a high-frequency discharge.

This paper presents the results of an experimental study of the jet thrust of ionized nitrogen flowing from the working chamber of an experimental sample of an accelerator ion thruster into a vacuum space. The resonant aerodynamic method (RAM-method) was chosen as the main research method. A method for determining low thrust and the design of a stand for implementing the RAM- method are proposed. The object of research is a prototype of an accelerator two-gap ion thruster with a solid-state microwave plasma generator and a toroidal resonator. The study showed that a 2.5 W microwave generator together with a 2.5 W accelerating potential difference voltage source at a nitrogen consumption of 0.1 mg/s creates an ion jet, the speed of which reaches 100 km/s. The current of the ion jet was 5.5-6 μA. The jet thrust was 0.141-0.188 μN.

This paper presents the results of an experimental study of the jet thrust of a mixed jet of neutral and ionized nitrogen flowing from the working chamber of an experimental sample of an accelerator ion thruster into a vacuum space. The main method of the study was the aerodynamic double angle method (AMαβ-method). The method of determining low thrust and the design of the stand for the implementation of the AMαβ-method are proposed. The object of research is a prototype of an accelerator two-phase ion thruster with a solid-state microwave plasma generator and a toroidal resonator. The study showed that a 2.5 W microwave generator together with a 2.5 W accelerating potential difference voltage source with a nitrogen consumption of 0.05 -1 mg/s can increase the speed of the working gas by 2.3 times. The jet thrust, according to the test results, was 1-3.6 μN. It is shown that the thrust components (the gas-dynamic component, the ion component of a high-frequency discharge, the ion component of a glow discharge) have different levels depending on the mass flow rate of the gas.

The paper presents the results of research to determine the dynamic component of the force of the jet stream of a microwave ion engine. The dynamic component was determined by an adiabatic calorimeter based on a heat flux density sensor. Experimental studies have shown that with a working fluid consumption (nitrogen) from 0.01 to 0.08 mg/s, the thrust of the micro-motor was from 1.45 to 13 μN. The calorimetric method gives inflated thrust values presumably due to ohmic heating in a DC glow discharge.

The concept of deterministic chaos at the initial development stage was considered as an unusual phenomenon that never arose in the solution of practical problems and was of interest only for a narrow circle of scientists. However, later chaotic dynamics was discovered in a large number of different systems. Further development revealed a number of practical problems, when there were chaotic regimes, sometimes harmful, and sometimes useful. Practically important classes of problems have appeared, when a non-linear system must be controlled, reduced, or, on the contrary, increased in degree of randomness.

This paper presents the results of an experimental study of the parameters of nitrogen, argon and helium plasma obtained in high-frequency capacitive ring discharge at a pressure of 35 Pa. The parameters were determined by a single Langmuir probe. Work is being carried out as part of a project to develop a backlash ion microwave plasma generator. The object of study is ionized gas formed in the ring capacitance gap of a microwave solid-state generator emitter on the MOSFET transistor MRF284. The power consumed by the microwave generator in the study is no more than 5 W. The work resulted in getting the volt-ampere characteristics of a high-frequency discharge in low-pressure gas and determining the main plasma parameters.

A novel, to the best of our knowledge, approach to the design of the single-photon sources emitting in the spectral regions of 1060 and 1337 nm was developed. A unique hybrid structure based on colloidal CdSe/CdS/ZnS nanocrystals and neodymium(III) 1,3-diketonate was created. Direct energy transfer from the CdSe/CdS/ZnS single nanocrystal to the near-infrared (NIR) luminescent Nd(III) complex was observed and investigated by spectroscopic methods. The single-photon emission mode was confirmed for the novel hybrid source by Hanbury Brown and Twiss experiments.

This paper presents the results of an experimental study of the velocity of ionized nitrogen flowing from the working chamber of an experimental sample of the primary accelerating system of the ion engine into the vacuum space. The main method of research was chosen calorimetric method. The design of a small spacecraft jet propulsion system with ionized gas acceleration in the high-frequency gap of a microwave generator is proposed. The object of the study is a prototype of the primary ion engine accelerator system with a solid-state microwave plasma generator and an accelerating gap. The study showed that a 3-watt microwave generator together with a pulsed voltage source of an accelerating potential difference of 1 W at a nitrogen consumption of 2.5 mg/s creates an ion jet whose speed reaches 30 km/s.the Current of the ion jet was 2-2.5 mkA. The field strength of the accelerating potential difference was 4450 V / m.

The paper presents the results of experimental studies of an arcjet thruster in pulsed mode of operation on nitrogen with a thrust value of up to 32 mN and energy consumption of up to 30 watts. The pulse mode of operation of the arcjet thruster is provided by the developed power source. At measured values of temperature at the nozzle and pressure in the arc chamber of the engine in a pulsed mode of operation define the basic characteristics of gas-dynamic functions of gas flow. The forecast of the achieved values of the specific impulse when using ammonia as a working fluid is carried out

With the use of a novel thermoluminescence technique, a new type of surface traps is observed in colloidal CdSe nanocrystals of planar geometry (nanoplatelets). The emptying of these traps, which cannot be detected by means of the conventional thermally stimulated luminescence scheme, proceeds via a cascade process involving their own excited states. An energy-level diagram of nanoplatelets taking into account the specific characteristics of these traps is proposed and the density of surface states, featuring two peaks at energies of 100 and 280 meV, is determined.

The temperature dependence of the photoluminescence intensity of colloidal CdSe nanocrystals having 5 nm in diameter was studied. It was demonstrated that the photoluminescence intensity exhibits a hysteresis at temperatures below 220 K. This effect was explained by a model taking into account formation of an additional nonradiative relaxation channel associated with Auger recombination promoted by hole trapping on the surface of the nanocrystals. The activation energy of the hole release process obtained in the framework of the model was 0.7 eV.

The temperature dependencies of the luminescence spectra of 5-nm-diameter CdSe semiconductor nanocrystals synthesized by colloidal-chemistry methods are investigated. The two bands observed in these spectra around 2.01 and 1.37 eV correspond to band-to-band transitions and luminescence of defect states, respectively. A model explaining the temperature behavior of the luminescence band intensities both upon cooling and heating is put forward. A new modification of spectrally resolved thermostimulated luminescence technique making it possible to determine the activation energies and the character of traps responsible for the temperature dependence of the luminescence intensities is suggested. This technique is used to obtain the activation energies of the emission and capture of electrons at traps (190 and 205 meV, respectively) and to determine the depth of the electron level (57 meV) responsible for luminescence in the 1.37-eV region.

The statistics of luminescence from single CdSe/CdS core/shell semiconductor nanocrystals under CW laser excitation at room temperature is experimentally investigated by recording sequences of absolute arrival times of the emitted photons. It is shown that the correlation coefficient for consecutive intervals between the photon-arrival times differs from zero. The correlation persists for photon-arrival intervals separated by two or more photon-detection events, until the time between the two intervals becomes, on average, as long as 180 ms, which corresponds to about 103 detected photons. A simulation of the luminescence process supports the conclusion that this correlation is linked to the blinking character of the quantum-dot luminescence.

The blinking fluorescence of a single nanoparticle excited by CW laser radiation was studied. In the case of a low time resolution setup, blinking fluorescence appears to be a continuous emission. Blinking can nevertheless be established if we measure the photon distribution function in such quasi-continuous fluorescence.

A single complex molecule with conformational changes (conformations 0 and 2) is considered. When such a molecule is irradiated by cw-laser light it can randomly change the intensity or polarization of its fluorescence due to jumps from one conformation to another. In fact, the molecule manifests itself either like the 0-type or the 2-type emitter. An expression for the matrix s{sub {alpha}{beta}}(t) called the start-stop correlator (waiting time distribution) in which {alpha}=0,2 and {beta}=0,2 is derived. An expression for the matrix p{sub {alpha}{beta}}(t) called the full correlator is derived as well. It determines the density of the probability of finding an event of {alpha} type and an event of {beta} type separated by time interval t. A relation between matrices s{sub {alpha}{beta}}(t) and p{sub {alpha}{beta}}(t) is found. A mathematical expression for the distribution w{sub N}(T) of events measured in time interval T is derived. It is expressed solely via the matrix s{sub {alpha}{beta}}(t). Numerical calculations of the event distribution function for various rates of intra- and interconformational jumps are carried out with the help of the formula for w{sub N}(T) and by the Monte Carlo method. Both methods of the calculation yield identical distributions. Fluctuating fluorescence intensity I(t) for amore » bin time of 5 ms is calculated for slow and fast interconformational jumps. A relation is found between the autocorrelation function g{sup (2)}(t) of fluorescence measurable in experiments and the matrix p{sub {alpha}{beta}}(t) calculated theoretically.« less

Distribution function w(N)(T) for photons created by three-level nanoparticle in time interval T under cw laser excitation is calculated for various methods of photon counting. It is found that each exponential process exp(-lambda(i)t) in quantum dynamics of three-level nanoparticle manifests itself via Poissonian function P(N)(lambda(i)t)=(lambda(i)t)(N) exp(-lambda(i)t)/N! in the photon distribution function w(N)(T). The distribution function w(N)(T) is expressed via two or three integrals of two or three Poissonian functions P(N)(lambda(i)t). The simple mathematical expression for w(N)(T) enables one to calculate photon distribution in blinking fluorescence with on and off intervals. A scaling between photon distribution function w(N)(T) and photoelectric pulse distribution function w(n)(T) is found. Comparison of the theoretical distribution w(n)(T) and the distribution measured in blinking fluorescence of single polymer molecule dPPV-PPyV and complex organic molecule 1,1(')-didodecyl-3,3,3('),3(')-tetramethylindocarbocyanine perchlorate (DiI) is carried out. The theoretical distributions are able to describe those found in an experiment.

Quantum confinement effect and its influence on absorption and photoluminescence spectra of CdSe nanoparticles chemically synthesized in thermotropic ionic liquid crystal of cadmium octanoate are studied. It was found out that the spectral resolution grows with decrease of temperature, so it becomes possible to distinguish the band-edge luminescence from the bands associated with the presence of surface defects. Obtained spectra were analyzed theoretically and the energy diagrams for samples with 1.8 nm and 2.6 nm nanoparticles were calculated.

CdS colloidal nanocrystals with an average size of 4.5 nm and oleic acid as surfactant were studied using photoluminescence spectroscopy and time-correlated single photon counting technique at different temperatures. Observed spectra revealed three thermally activated luminescence bands at 2.15, 1.76, and 1.37 eV in addition to conventional band edge recombination of the nanocrystals. We present a kinetic model based on concept of single emitters which quantitatively describes the luminescence of the ensemble of the nanocrystals in the temperature range 10–300 K. We determined activation energies (18.2 and 8.6 meV) for transitions responsible for the luminescence. The 1.76 eV band most probably emerges from the intrinsic defects on the surface of CdS, whereas bands at 2.15 and 1.37 eV result from the influence of oleic acid bonded to the surface of the nanocrystals.

A theoretical six-level model for blinking fluorescence of single PPV-PPyV copolymer molecule excited by CW-laser light is proposed. The model has been chosen in accordance with the following facts found in the Paul Barbara group experiment: (i) alternation of two types of fluorescence with moderate and strong levels of emission, (ii) existence of "dark" states with no fluorescence, (iii) linear dependence of inverse on-interval duration on laser intensity, and (iv) existence of laser intensity independent off-intervals. Relations between the distribution function w''(N, T) for photons emitted by a single molecule, the distribution function w'(N, T) for photons arriving at photomultiplier tube (PMT) and photo-electric pulse distribution w(N, T) created in a PMT are discussed. The theory is able to describe pulse distribution function w(N, T) measured experimentally at signal acquisition time T = 0.1 s. Values of all rate constants of the model have been found from comparison of the theory with the experiment. Distributions w(on, off)(t) of on- and off-times and distribution w(N, T) of pulses have been calculated for infrequent and frequent inter-conformational jumps in single copolymer molecule.