Cooling techniques for excilamps driven by dielectric barrier discharge

Our study describes effective techniques to transfer heat away from UV emitters based on dielectric barrier discharge excilamps. It presents findings from an investigation into the efficiency of excilamp radiation when cooled by air, inert gas, and liquid refrigerants. The devised cooling techniques were used to create radiation sources with a UV power density of up to 117 mW∕cm2

Computational and experimental study of time-averaged characteristics of positive and negative DC corona discharges in point-plane gaps in atmospheric air

The use of stationary solvers instead of approximate solution methods or time-dependent solvers, which are standard tools in gas discharge modeling, allows one to develop a very fast and robust numerical model for studying the time-averaged characteristics of dc corona discharges. Such an approach is applied to dc corona discharges in point-plane gaps in ambi ent air. A wide range of currents of both voltage polarities and various gap lengths are investigated, and the simulation results are validated by comparing the computed current–voltage characteristics and spatial distributions of the radiation intensity with experimental results. Specific features of the numerical and experimental results at both polarities are discussed.info:eu-repo/semantics/publishedVersio

Apokamps produced by repetitive discharges in air

New experimental and computational data on apokamps produced by repetitive discharges in air, including a detailed description of the research techniques used, are presented. It has been shown that plasma bullets–streamers in apokamps at low frequencies could start not only from the bright offshoot but also directly from the discharge channel. The experimental and computational data demonstrate that the visual color of apokamp changes from blue to red as the intensity ratio of the second to the first positive nitrogen system decreases with the decreasing pressure

NOx formation in apokamp-type atmospheric pressure plasma jets in air initiated by a pulse-repetitive discharge

The decomposition products of atmospheric pressure plasma of repetitive pulsed discharge in apokamp and corona modes were determined by optical and chemical methods. It is shown, that the decomposition products contain mainly nitrogen oxides NOx. A brief review of the plasma- and thermochemical reactions in the pulsed discharges was made. The review and experimental data allow us to explain the reactive oxygen species formation mechanisms in a potential discharge channel with apokamp. The possible applications of this plasma source for treatment of seeds of agricultural crops are discussed

Presowing XeCl excilamp irradiation of crops: field research and prospects

Here we present research data demonstrating how crop seeds response to ultraviolet produced by a barrier-discharge XeCl* excilamp with a wavelength of 290–320 nm (82–88 %). The data show that presowing ultraviolet treatment is stimulatory to seed germination and plant growth. Ultraviolet treatment increases the seed germinability by 20–30 % and the plant fresh weight by 54 %, compared to untreated control samples, and provides a developed root system with long twisted segments. The research results are encouraging for upgrading the UV technology to larger-scale seed irradiation

Изотопный состав атмосферных осадков и природных вод в районе Баренцбурга (Шпицберген)

In 2016–2017, during Russian Arctic Expedition on Svalbard (RAE‑S) we have collected the samples of atmospheric precipitation, terrestrial waters, snow and ice on Spitsbergen island in the vicinity of Grønfjorden. The measurements of stable water isotope content (δ18O and δD) in the atmospheric precipitation has allowed to draw the Local Meteoric Water Line (δD = 6,93δ18O − 0,35) and to analyze the relationship between the isotopic content and condensation temperature. Aside from this, the d-excess values in precipitation (dexc= δD − 8δ18O) was interpreted as a marker of the moisture source. It has been demonstrated that the isotopic content of the surface waters (lakes and rivers) clearly points to the dominating type of feeding (atmospheric, ground) of these hydrological objects. We have discovered the interannual variability of the isotopic composition of Lake Kongress water during 2 years and defined the sources of water in its tributes: 13 of them have atmospheric source and 9 – ground source. In general, isotopic content of water in the vicinity of Grønfjorden (mean values are: δ18O = −10,3 ‰, δD = −72,5 ‰) is higher than in other regions of Svalbard.Ключевые слова: атмосферные осадки, изотопный состав, природные воды, Шпицберген. Приведена интерпретация изотопных исследований проб воды, снега и льда, отобранных на ледниках Альдегонда, Западный и Восточный Грёнфьорд и в их долинах (озёра, снежники, реки), а также в долине оз. Конгресс. На основании анализа изотопного состава атмосферных осадков в посёлке Баренцбург в 2016–2017 гг. обсуждается использование изотопного состава как индикатора источника влаги для атмосферных осадков