2010, Гармаш, А. А., Гармаш, Александр Александрович, Герасимов, Ю. М.

2019, Klokov, V., Kargin, N., Garmash, A. A., Guzniaeva, E., Клоков, Владимир Александрович, Каргин, Николай Иванович, Гармаш, Александр Александрович, Гузняева, Екатерина Александровна

The paper presents a description of design methodology for wide-band push-pull large-signal power amplifier based on GaN transistor with an output power of more than 10 W for high-performance Nonlinear Junction Detectors, which allows achieving optimal convergence of the theoretical model in practice, as well as increasing the efficiency of the power amplifier while maintaining a linear gain characteristic.

2019, Tereza, A. M., Smirnov, V. N., Shumova, V. V., Nazarova, N. V., Vlasov, P. A., Garmash, A. A., Власов, Павел Александрович, Гармаш, Александр Александрович

© 2019 Published under licence by IOP Publishing Ltd. The autoignition of a stoichiometric propane-oxygen mixture diluted with argon was studied behind reflected shock waves in the temperature range of 1230-1700 K at the total concentration of [M] 50 ∼ 10 -5 mol/cm 3 . Emission signals from electronically excited CH∗ (at λ = 429 nm) and C 2 ∗ (at λ = 516 nm) radicals were recorded. It was found that the CH∗ and C 2 ∗ emission time profiles reached their maxima almost simultaneously over the entire temperature range covered. The temperature dependence of the ignition delay time measured from the time of reaching the maximum by the CH∗ emission signal was simulated within the framework of several published data kinetic mechanisms. It was found that, at temperatures below 1400 K, all the kinetic models tested predict ignition delay times severalfold longer than that experimentally observed. Using a sensitivity analysis to the reaction rate constants in the induction period, the main reactions that affect the ignition delay time were identified.

2020, Muratov, A. V., Fronya, A. A., Antonenko, S. V., Kharin, A. Y., Aleshchenko, Y. A., Derzhavin, S. I., Karpov, N. V., Dombrovska, Y. I., Garmash, A. A., Kargin, N. I., Klimentov, S. M., Timoshenko, V. Y., Kabashin, A. V., Фроня, Анастасия Андреевна, Антоненко, Сергей Васильевич, Алещенко, Юрий Анатольевич, Гармаш, Александр Александрович, Каргин, Николай Иванович, Климентов, Сергей Михайлович, Тимошенко, Виктор Юрьевич, Кабашин, Андрей Викторович

Using methods of pulsed laser ablation from a silicon target in helium (He)-nitrogen (N2) gas mixtures maintained at reduced pressures (0.5-5 Torr), we fabricated substrate-supported silicon (Si) nanocrystal-based films exhibiting a strong photoluminescence (PL) emission, which depended on the He/N2 ratio. We show that, in the case of ablation in pure He gas, Si nanocrystals exhibit PL bands centered in the "red - near infrared" (maximum at 760 nm) and "green" (centered at 550 nm) spectral regions, which can be attributed to quantum-confined excitonic states in small Si nanocrystals and to local electronic states in amorphous silicon suboxide (a-SiOx) coating, respectively, while the addition of N2 leads to the generation of an intense "green-yellow" PL band centered at 580 nm. The origin of the latter band is attributed to a radiative recombination in amorphous oxynitride (a-SiNxOy) coating of Si nanocrystals. PL transients of Si nanocrystals with SiOx and a-SiNxOy coatings demonstrate nonexponential decays in the micro- and submicrosecond time scales with rates depending on nitrogen content in the mixture. After milling by ultrasound and dispersing in water, Si nanocrystals can be used as efficient non-toxic markers for bioimaging, while the observed spectral tailoring effect makes possible an adjustment of the PL emission of such markers to a concrete bioimaging task.

2019, Agafonov, G. L., Smirnov, V. N., Tereza, A. M., Shumova, V. V., Vlasov, P. A., Garmash, A. A., Власов, Павел Александрович, Гармаш, Александр Александрович

© 2019 Published under licence by IOP Publishing Ltd. Experimental investigations and detailed kinetic simulations of the formation of soot particles during pyrolysis of mixtures of acetylene with acetone and propane behind reflected shock waves are performed. Acetone and propane additives are found to substantially promote the process of soot formation as compared with that in acetylene-argon mixtures. Detailed kinetic simulations closely reproduce our own experimental results and published data. The kinetic model of soot formation is comprised of 4782 direct and reverse reactions involving 372 species. The predictive possibility of the kinetic model of soot formation is tested by describing the effect of acetone and propane additives to acetylene-argon mixtures on soot formation. All the kinetic parameters of the unified kinetic model are kept constant. The indicated additives enhance the soot yield because polyyne-dominated pathway of soot nucleation, characteristic of unseeded acetylene-argon mixtures, is augmented by the aromatic pathway, typical of most hydrocarbons.