The work is devoted to identifying the features of plant growth and development under laboratory conditions after presowing stimulation of seeds of pine (Pinus sylvestris L.), thuja (Thuja occidentalis L.) and eggplant (Solanum melongena L., variety "Universal") by UVB radiation of XeCl-excilamp. In all cases, conditions were identified in which UVB stimulation accelerates the germination of these seeds and the formation of seedlings. Additionally, microcoping of germinating 10-day-old thuja seeds performed on sections shows that the seeds show clear differences compared to the untreated control. If in the control, the seeds were just beginning to germinate (the appearance of the germ root), then in the experimental samples, on average, 5% of the seeds passed to the stage of development and formation of the seedling, had a developed root, hypocotyl, colored cotyledons, which began to shed the seed rind. The obtained primary data confirm the prospects of using narrow-band UVB radiation of XeCl-excilamps for pre-sowing stimulation of plant seeds.
Using an electrode with a ceramic coating, a new method for the formation of an apokampic discharge in the pressure range of 30-150 Torr has been obtained. It was found that the average plasma bullets velocity propagated from such an electrode can reach 520 km/s. The results obtained are in good agreement with the simulation results obtained earlier in the framework of the streamer model.
Using emission spectra, the electronic, vibrational, rotational, gas temperatures and the reduced electric field strength at different distances along the propagation of the apokamp from the discharge channel at an air pressure of 150 Torr, a voltage of 7.6 kV, and a frequency of 37.5 kHz were determined. To determine the above values of plasma parameters, the methods of optical emission spectroscopy were used, after which the experimentally obtained values were compared with the values obtained in the course of modeling the emission spectra of the discharge plasma using a code based on the radiation-collisional plasma model. It is shown that the values of the electron temperature and reduced field strength increase abruptly at a height of ~ 12 mm above the discharge channel, marking the transition from the offshoot zone to the positive streamer zone. The gas temperature along the distribution of the apokamp decreases exponentially and at a distance of 75 mm reaches about 530° C (which is about 3 times less than at the base of the apokamp). The data obtained are in agreement with the streamer model of the plasma plume of the apokamp and allow us to hope for the creation of a plasma source based on an apokampic discharge with a moderate gas temperature at the end of the plasma plume.
Now, agriculture strives for advanced technologies that would speed up the seed germination, reduce the plant disease incidence, and enhance the crop yield. In this connection, more and more studies address ultraviolet irradiation of seeds and plants as a way to increase their sowing quality. In this paper, XeCl-excilamp (λ~ 300-320 nm) ‒ as a simulator of solar short-wave radiation ‒ is used in the quality of source of ultraviolet radiation. A new data on morphometric and morphological indicators of development of a number of economically valuable crops (parsley, cucumber, pumpkin, zucchini) exposed to XeCl-excilamp are presented. In particular, it is shown that the ultraviolet treatment increases the number of zucchini fruits ("Tsukesha" sort) by an average of 40%, compared to untreated control samples and increases the area of the assimilating surface of leafs (in the first week after germination and further in a month and two months) by an average of one and a half times. Compared with the control 90-second treatment of seeds zucchini led to a higher content of vitamin C in fruits and more than a twofold reduction of nitrate to 64±7 mg/kg. Similar results were obtained for the pumpkins. First processing radiation of XeCl-excilamp were subjected parsley seeds. Found processing conditions in which you can increase the yield by an average of 20%. The obtained indicators allow us to draw a conclusion about the economic feasibility of XeCl-excilamp seeds illumination and confirm our conclusions about the prospects of such a procedure for pre-sowing plant seeds.
A new models of Xe2-excilamp (with maximum of radiation spectra at 172 nm) developed in Optical Radiation Laboratory of High Current Electronics Institute are presented. The task of creating a lamp with the most simple design embodiment was solved. The bulb of such an excilamp was made from a single quartz tube with a diameter of 22 mm and a length of 12 cm. The length of the discharge region was 4 cm. The lamp was supplied with voltage pulses from a generator of 2 μs with a repetition frequency up to 100 kHz. A radiant exitance of 3.5 mW/cm2 has been obtained. This value has not changed after 2400 hours of excilamp operation. The report will also describe other designs of Xe2-excilamps.
The paper demonstrates the possibility of studying blue jets in laboratory apokamp discharges as a source of blue streamers that move upward from the discharge channel. Research data are presented on the formation of such streamers in low-pressure air at a voltage of tens of kilovolts, showing for the first time that they do arise at low (∼8 Hz) pulse repetition frequencies under pressures at which gigantic blue jets develop 10–20 km above the Earth. At a voltage of positive polarity with an amplitude of 33 kV, the streamer velocity in a pulsed apokamp discharge reaches 560 km/s. When applying microsecond voltage pulses of amplitude 15 kV with a repetition frequency of 50 kHz, the length of streamers ranges to more than 120 cm.
The paper studies the dynamics of a nanosecond diffuse discharge with no additional preionization at a voltage rise time of less than 1 ns and its effect on drinking and distilled water. It is shown that the diffuse discharge is formed due to avalanche charge multiplication initiated by fast electrons and is sustained by secondary breakdown waves through ionized gas channels. Fourier transform infrared spectroscopy reveals that repeated exposure to the discharge changes the absorption spectra of drinking and distilled water such that the stretching vibration band of OH groups broadens and lacks clearly defined peaks. The water conductivity after irradiation increases. Probably, this is due to cluster rearrangement of water molecules.
The energy dissipation processes in dielectric barrier discharge KrCl- and XeCl-excilamps at various voltage, frequencies and pulse duration are revealed by a pressure jump method. It is offered and tested a way of radiation power calculation in conditions of non-uniform filling of device bulb by discharge plasma. The previous data (Pikulev A.A., Sosnin E.A., 2010-2013) are confirmed. The regularity was formulated: conditions of maximal ultraviolet radiation power corresponds to conditions of maximal heat release in plasma.
The paper proposes a new atmospheric pressure plasma jet (APPJ) source for operation in air and nitrogen. The conditions for the formation of stable plasma jets 4 cm long are determined. Energy and spectral measurement data are presented.
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