Abstract
Experimental data are presented on the evolution of a helium atmospheric pressure plasma jet driven by a tailored voltage waveform generated as bunches of voltage pulses consisting of a ...superposition of
$$\approx 43$$
≈
43
kHz bipolar square pulses and
$$\approx 300$$
≈
300
kHz oscillations. The characteristics of directed ionization waves (guided streamers) are compared for bunches with different first pulse polarities and different bunch duty cycles. The longest and brightest streamers are achieved at the voltage bunch with the first negative pulse and a minimum duty cycle. The dynamics of streamers at the voltage bunch with the first positive pulse are characterized by the shortest length and a lower brightness. The plasma jet length can be smoothly changed by varying the number of pulses in the bunch and the polarity of the first pulse. It is thus possible to precisely localize the region of a strong field in space by combining the parameters of the applied voltage (the duty cycle and polarity of the first pulse of a bunch) with a stepwise propagation mode of a guided streamer.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This work compares the presowing treatment of winter wheat seeds with a low-temperature plasma, a constant high-voltage electric field, a plant protection disinfectant, and cold hardening on the ...resistance of seedlings to freezing and their morphophysiological characteristics at the initial stage of germination. Various treatment combinations were considered, including the effect of the disinfectant jointly with low-temperature plasma treatment. The greatest stimulating effect from the point of view of seedlings’ morphophysiological characteristics was achieved when seeds were cold-hardened. The action of low-temperature plasma is noticeable up to the third day of germination. The treatment with the low-temperature plasma of seeds pretreated and not-pretreated with the disinfectant had a similar effect on the morphophysiological characteristics of seedlings. The plasma treatment and the electric field were combined with each other, i.e., the plasma treatment effects were added to the electric field effects. Resistance to low temperatures was increased with the hardening of seeds treated with the electric field and the disinfectant. Resistance to low temperatures was reduced when treated with the electric field and/or low-temperature plasma after being treated with the disinfectant.
The paper presents an analysis based on conflicting data regarding the results of the treatment of soft spring wheat seeds by ozone generated from humid air and dry oxygen. Morphological ...characteristics of treated seeds (the length of a sprout, the total length of roots and the sprout-to-root ratio), 7-day germination ability along with the extent of 7-day-old seedlings contamination are considered in terms of ozone concentrations. The experiments were conducted using the wheat seeds of 2013 and 2014 yields. For the same concentrations of ozone, morphological characteristics of treated seeds and efficiency of seed surface treatment changed similarly for both ways of ozone production. However, the efficiency of seeds treatment and stimulation of seeds germination with ozone are not correlated; and the germination ability of the seeds is not changed after ozone treatment.
A coaxial electrode configuration with surface dielectric barrier discharge is designed to generate a cold plasma jet emerging into the ambient air. A technique to determine the length of plasma ...extension based on the measurements of average values of current and applied voltage is proposed. The capacity of the discharge cell calculated using current and voltage values agrees with the capacity obtained from the integral length of a plasma layer along a dielectric surface. The average charge deposited on the dielectric surface is determined.
Abstract Pursuing of straightforward and cost‐effective methods for synthesizing high‐performance anode materials for lithium‐ion batteries is a topic of significant interest. This study elucidates a ...one‐step synthesis approach for a conversion composite using glow discharge in a nickel formate solution, yielding a composite precursor comprising metallic nickel, nickel hydroxide, and basic nickel salts. Subsequent annealing of the precursor facilitated the formation of the Ni@NiO composite, exhibiting exceptional electrochemical properties as anode material in Li‐ion batteries: a capacity of approximately 1000 mAh g −1 , cyclic stability exceeding 100 cycles, and favorable rate performance (200 mAh g −1 at 10 A g <M−.1 ). Comparative analysis across various methods for synthesizing NiO‐based materials underscored the superiority of the Ni@NiO composite. Furthermore, an assessment of resource costs demonstrated the cost‐effectiveness and scalability of the approach in terms of resource consumption per Ah. Lastly, the integration of a Ni@NiO anode with an NMC532 cathode in a full battery highlights Ni@NiO's potential for conversion anodes, achieving a practical gravimetric energy density of 92 Wh kg −1 .
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Cold non-equilibrium atmospheric pressure plasma flows with the gas temperature close to the room temperature are rather promising for biomedical applications1,2. However, technologies for processing ...living materials take the special requirements to the characteristics of a generated plasma jet. For instance, to treat an object without significant heating up, the gas temperature must be accurately controlled.
The study describes the behavior of plasma streamer discharges in helium and argon atmospheric pressure plasma jets fed by dielectric barrier discharge with the specific AC voltage waveform, which ...has hundred-kHz oscillations deviated from the zero level. The equivalent electrical and gas feeding conditions for producing both helium and argon jets have been provided. The plasma jet in helium is shown to have a diffusive structure and is formed by guided ionization waves, whereas an argon plasma jet is formed by numerous filaments which can have several branches on their ends. Repetitive stepwise plasma bullet formation has been observed in He plasma jet, whereas random and stochastic branching of the streamer has been recorded in Ar plasma jet. Both types of streamers have an approximately equal maximum of their length but significantly differ with the lifetime: they exist for about 1 and almost 8 μs in the argon and helium plasma jets, correspondingly.
The design of a new flash X-ray diagnostic system for the determination of metal vapor concentration in high-current discharges in high-pressure gas is presented. The system consists of a pulsed ...X-ray source with a hardness of 20-50 keV and an X-ray CCD camera. A high-voltage generator with a pulse duration of 50 ns was used. The new X-ray tube of through-target type was designed. Experimental research on the diagnostic of high-current discharges with a Z-pinch geometry was carried out. The parameters of the experiments are as follows: dJ/dt ~10 9 -10 10 A/s, discharge current amplitudes up to 1 MA, and initial gas pressures of 2.5 kPa-35 MPa. Experimental data on the spatial metal vapor distribution in the discharge gap, provided by electrode erosion, were obtained.
Electrode plasma jets formation and structure in powerful pulsed gas discharge at high pressures were investigated. Typical experimental parameters were current amplitude of 100-700 kA, pulse ...duration of 150-500 μs, current rise rate of ~10 10 A/s, initial gas pressure of 1-10 MPa under which intense electrode plasma jets is being formed. Discharge was initiated by wire explosion. The structure of jets was studied by different high-speed diagnostic methods. The jet is shown to consist of a central metal zone surrounded by a gas plasma sheath in which, gas in flowed from the surrounding discharge channel space. Electrode plasma jets play a major role in heat and mass transfer between discharge channel and the surrounding gas.
The dependence of multi-chamber arrester quenching efficiency on altitude over sea level was investigated. It was found out that quenching efficiency drops by 20% at pressure of 50 kPa which ...corresponds to altitude of 5 km.
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