Journal articles: 'High-current nanosecond discharge'

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Kuzenov, Victor V., Sergei V. Ryzhkov, and Aleksey Yu Varaksin. "Computational and Experimental Modeling in Magnetoplasma Aerodynamics and High-Speed Gas and Plasma Flows (A Review)." Aerospace 10, no. 8 (2023): 662. http://dx.doi.org/10.3390/aerospace10080662.

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This paper provides an overview of modern research on magnetoplasma methods of influencing gas-dynamic and plasma flows. The main physical mechanisms that control the interaction of plasma discharges with gaseous moving media are indicated. The ways of organizing pulsed energy input, characteristic of plasma aerodynamics, are briefly described: linearly stabilized discharge, magnetoplasma compressor, capillary discharge, laser-microwave action, electron beam action, nanosecond surface barrier discharges, pulsed spark discharges, and nanosecond optical discharges. A description of the physical mechanism of heating the gas-plasma flow at high values of electric fields, which are realized in high-current and nanosecond (ultrafast heating) electric discharges, is performed. Methods for magnetoplasma control of the configuration and gas-dynamic characteristics of shock waves arising in front of promising and advanced aircraft (AA) are described. Approaches to the control of quasi-stationary separated flows, laminar–turbulent transitions, and static and dynamic separation of the boundary layer (for large PA angles of attack) are presented.

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Li, Handong, Yutai Li, Xinxin Wang, Xiaobing Zou, Peng Wang, and Haiyun Luo. "Investigation of the microsecond-pulse acoustic wave generated by a single nanosecond-pulse discharge." Physics of Plasmas 29, no. 5 (2022): 053508. http://dx.doi.org/10.1063/5.0085748.

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A single nanosecond-pulse discharge can produce a high-intensity pulsed acoustic wave. The pulse width of the acoustic wave is much wider than that of the current, more than 20 μs at 30 cm from the source, which is the basis of synthesizing low-frequency sound by repetitively nanosecond-pulse discharges. The investigations of electroacoustic characteristics and the sound formation process of the single nanosecond-pulse discharge are vital to advance this technology. In this paper, an experimental platform for the single nanosecond-pulse discharge was built, and time-domain waveforms of the voltage, the current, and the sound pressure were measured. The effects of electrode shape, current limiting resistors, and current pulse width on the acoustic wave were discussed. To analyze the formation process of the acoustic wave, the gas densities near the electrodes at different moments after the discharge were diagnosed by laser Schlieren photography. The result shows that the formation of the acoustic wave is much slower than the discharge. A two-stage model was developed to qualitatively describe the formation process of the acoustic wave, and numerical calculations were carried out using thermodynamic and hydrodynamic equations. At the end of the discharge, a huge pressure difference is formed inside and outside the gas channel due to the Joule heating, which can be considered as a shock wave. During the outward propagation, the wave tail is elongated by the difference in sound velocity at each point, and the thickness of the shock wave increases due to the dissipation. This eventually leads to the half-duration of more than 20 μs.

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Znamenskaya, I. A., D. A. Koroteev, and N. A. Popov. "A Nanosecond High-Current Discharge in a Supersonic Gas Flow." High Temperature 43, no. 6 (2005): 817–24. http://dx.doi.org/10.1007/s10740-005-0129-x.

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Шуаибов, А.К., А.Й. Миня, А.Л. Енеди, И.В. Шевера, З.Т. Гомоки та В.В. Данило. "Характеристики наносекундного разряда с жидким неметаллическим электродом в воздухе". Elektronnaya Obrabotka Materialov 53, № 2 (2017): 45–49. https://doi.org/10.5281/zenodo.1053272.

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The article presents the results of the development of a high current nanosecond discharge module above the liquid surface (distilled water and ethyl alcohol solution). The electrical and optical characteristics of the discharge were examined. The conditions for the discharge ignition above fluids on the base of ethyl alcohol and distilled water, and of the discharge between the metal (blade) and the liquid electrode were defined. These discharges are of interest for use in water purification systems (purification of the water surface from the organic films) and the synthesis of nanoparticles (carbon). Приведены результаты разработки модуля сильноточного наносекундного разряда над поверхностью жидкости (дистиллированной воды и раствора этилового спирта). Исследованы электрические и оптические характеристики разряда. Определены условия зажигания разряда над жидкими средами на основе этилового спирта и дистиллированной воды и разряда между металлическим (лезвие) и жидким электродами. Эти разряды представляют интерес для использования в системах очистки воды (поверхности воды от органических пленок) и синтеза наночастиц (углерода).

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Levko, Dmitry, and Laxminarayan L. Raja. "Influence of the electron field emission on the magnetized direct current high-pressure discharge." Journal of Applied Physics 132, no. 24 (2022): 243301. http://dx.doi.org/10.1063/5.0124685.

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The influence of electron field emission on the sub-normal mode of a magnetized direct current high-pressure helium discharge is analyzed using the two-dimensional axisymmetric fluid model. It is observed that in spite of accounting for a more intense electron emission mechanism, discharge still operates in the sub-normal mode. However, the field emission driven discharge is characterized by a smaller discharge voltage and a larger discharge current. For large values of the electric field enhancement factor, the discharge voltage can be as low as ∼40 V, and the discharge current is a few amperes. It is also seen that for large values of the field enhancement factor and small values of the ballast resistor, rather dense plasma (density ∼ 1017 m−3) can be generated on the nanosecond time scale.

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Zhang, Cheng, Zehui Liu, Jintao Qiu, Han Bai, Fei Kong, and Tao Shao. "Measurement of runaway electron beam current in nanosecond-pulse discharges by a Faraday cup." Laser and Particle Beams 36, no. 3 (2018): 369–75. http://dx.doi.org/10.1017/s026303461800040x.

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AbstractMeasurement of runaway electron beam (REB) is essential to investigate behavior of runaway electrons produced in nanosecond-pulse gas discharge. A Faraday cup is designed to measure the REB current in nanosecond-pulse discharge when the applied dV/dt is 75 kV/ns. The Faraday cup considers the impendence match with the oscilloscope and the design of the receiving part. The experimental results show that the measured REB current has a rise time of 348 ps and a full width at half maximum of 510 ps. The comparison of the measurement results by the Faraday cup and a REB collector confirm that the Faraday cup is able to measure REB current in nanosecond-pulse discharge. Furthermore, consecutive waveforms of the REB currents show stable results by using the designed Faraday cup. In addition, effects of the interelectrode gap, gas pressure, and cathode material on the REB current are investigated by the designed Faraday cup, and the measurement results provide characteristics of REB current under different conditions. The REB current decreases when the gap spacing or gas pressure increases. REB current increases with the cathode diameter. It indicates that the high-energy electrons are generated not only at the edge of the cathode but also on the side surface of the cathode.

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Popov, N. A. "Kinetic processes initiated by a nanosecond high-current discharge in hot air." Plasma Physics Reports 37, no. 9 (2011): 807–15. http://dx.doi.org/10.1134/s1063780x1108006x.

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Shuaibov, A. K., R. V. Gritsak, A. I. Minya, et al. "Gas-Discharge Point Source of UV Radiation Based on a Gas-Vapor Mixture of Argon and Copper." Elektronnaya Obrabotka Materialov 58, no. 4 (2022): 81–87. http://dx.doi.org/10.52577/eom.2022.58.4.81.

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The characteristics of a pulse periodic source of a long-range UV radiation with overvoltage pumping by a bipolar discharge of nanosecond duration between copper electrodes in argon at atmospheric pressure are investigated. Copper vapors were introduced into the discharge due to the ectonic mechanism, in which a sufficient amount of the electrode material vapors is introduced into the discharge gap due to microexplosions of inhomogeneities of the surface of metal electrodes in a strong electric field of an overvoltage high-current nanosecond discharge. The characteristics of an overvoltage nanosecond discharge at a distance between the electrodes of 2 mm are studied. The emission spectra of the discharge were analysed, and the intensity of the UV radiation of a point emitter was optimized depending on the supply voltage of the high-voltage modulator and the repeti-tion rate of discharge pulses. The identification of the emission spectra of plasma made it possible to establish the main excited plasma products that form the spectrum of the UV radiation of the plas-ma. The study of the spectral characteristics of plasma based on gas-vapor mixtures "copper – ar-gon" showed that the most intense were the spectral resonance spectral lines of the copper atom and ion. It was found that a space-uniform overvoltage nanosecond discharge was ignited between copper electrodes at an inter-electrode distance of 2 mm. It was found that the maximum value of the average UV power at p(Ar) = 101 kPa was observed for the UV-A range.

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Zhang, Shuai, Wen-chun Wang, Peng-chao Jiang, De-zheng Yang, Li Jia, and Sen Wang. "Comparison of atmospheric air plasmas excited by high-voltage nanosecond pulsed discharge and sinusoidal alternating current discharge." Journal of Applied Physics 114, no. 16 (2013): 163301. http://dx.doi.org/10.1063/1.4825053.

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Shuaibov, A.K., A.I. Minya, A.A. Malinina, et al. "Investigations of Synchronous Fluxes of Bactericidal UV Radiation of Transition Metal Oxides (Zn, Cu, Fe) in Pulsed Gas-Discharge Reactor on the Base of Overstressed Nanosecond Discharge in Air." Elektronnaya Obrabotka Materialov 55 (4) (August 16, 2019): 56–63. https://doi.org/10.5281/zenodo.3369706.

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The characteristics of an overstressed, high-current nanosecond discharge in atmospheric air between zinc, copper, and iron electrodes are given, with a distance  between the electrodes of 1–3 mm. It is established that this discharge is a point source of ultraviolet radiation in the spectral range of 200–300 nm and a stream of nanoparticles of zinc, copper, and iron oxides. The results of optimization of the UV emitter depending on the pumping conditions and parameters of the discharge medium, as well as the optical characteristics of the film nanostructures of transition metal oxides deposited on the surface of a glass substrate are presented.

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Кузнецов, А. В., В. А. Морозов, Г. Г. Савенков та В. В. Столяров. "Роль добавок графена в стойкости оксида алюминия хрупкому разрушению при импульсных электрофизических воздействиях". Журнал технической физики 91, № 3 (2021): 484. http://dx.doi.org/10.21883/jtf.2021.03.50527.247-20.

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The study of the dynamic strength for Al2O3 nanoceramics with different content of five layer graphene under the action of a high-current electron beam and a high-voltage electric discharge of nanosecond duration are presented. It was found that an increase in the graphene content in the composite leads to the embrittlement of the nanocomposite. Key words: .

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Шуаибов, А. К., А.Й. Миня, З.Т. Гомоки, В.В. Данило, and Р.B. Пинзеник. "Characteristics of a high-current impulse discharge in air with ecton mechanism of vapour injection of copper in the discharge gap." Elektronnaya Obrabotka Materialov 54 (February 15, 2018): 46–50. https://doi.org/10.5281/zenodo.1168351.

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The characteristics of a bipolar high-current nanosecond discharge in the air between the copper electrodes is given. With an inter-electrode distance of 1-2 mm and the air pressure of 0.05-3.0 atm the conditions of obtaining a homogeneous volume discharge in the inhomogeneous electric field, associated with the generation of a beam of runaway electrons and concomitant X-ray radiation, are realized. It is shown that this discharge is a simple point source of radiation in the spectral range of 200-230 nm on the transitions of singly charged copper ions. The results of optimization of the UV - emitter depending on the pump conditions and parameters of the discharge medium are provided. It is found that, under the influence of a discharge, a deposition of thin nanostructured   membranes made of electrodes erosion products and products of dissociation of air molecules is possible.

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Wei, Ya Bo, Li Zhang, Peng Chao Jiang, Shuai Zhang, and De Zheng Yang. "Optical Diagnosis of Atmospheric Pressure Gas-Liquid Diffuse Discharge Excited by Nanosecond Pulse Voltage." Advanced Materials Research 1058 (November 2014): 158–61. http://dx.doi.org/10.4028/www.scientific.net/amr.1058.158.

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In this paper, A bipolar high voltage pulse with 20 ns rising time was employed to generate diffuse gas-liquid diffuse discharge in helium, and dielectric-free electrode configuration is used to generate room temperature plasma in small gas flow rate, which can be considered as a effective method to reduce the production cost. Discharge images, waveforms of pulse voltage and discharge current, and emission spectra of active species are measured.

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Herrmann, Antoine, Joëlle Margot, and Ahmad Hamdan. "Influence of Voltage Rising Time on the Characteristics of a Pulsed Discharge in Air in Contact with Water: Experimental and 2D Fluid Simulation Study." Plasma 7, no. 3 (2024): 616–30. http://dx.doi.org/10.3390/plasma7030032.

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In the context of plasma–liquid interactions, the phase of discharge ignition is of great importance as it may influence the properties of the produced plasma. Herein, we investigated the influence of voltage rising time (τrise) on discharge ignition in air as well as on discharge propagation on the surface of water. Experimentally, τrise was adjusted to 0.1, 0.4, 0.6, and 0.8 kV/ns using a nanosecond high-voltage pulser, and discharges were characterized using voltage/current probes and an ICCD camera. Faster ignition, higher breakdown voltage, and greater discharge current (peak value) were observed at higher τrise. ICCD images revealed that higher τrise also promoted the formation of more filaments, with increased radial propagation over the water surface. To further understand these discharges, a previously developed 2D fluid model was used to simulate discharge ignition and propagation under various τrise conditions. The simulation provided the spatiotemporal evolution of the E-field, electron density, and surface charge density. The trend of the simulated position of the ionization front is similar to that observed experimentally. Furthermore, rapid vertical propagation (<1 ns) of the discharge towards the liquid surface was observed. As τrise increased, the velocity of discharge propagation towards the liquid increased. Higher τrise values also led to more charges in the ionization front propagating at the water surface. The discharge ceased to propagate when the charge number in the ionization front reached 0.5 × 108 charges, irrespective of the τrise value.

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Tang, Xiongmin, Tianhong Jiang, and Wenrui Fang. "A unipolar compact nanosecond pulsed power supply with high power factor for dielectric barrier discharge applications." Review of Scientific Instruments 93, no. 8 (2022): 084707. http://dx.doi.org/10.1063/5.0089020.

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A high voltage with a very short duration and fast rising time is beneficial to generate uniform and diffuse plasma in dielectric barrier discharge (DBD) loads, and a power supply with a high power factor (PF) can reduce the impact on the power grid. According to two requirements, a unipolar high voltage pulsed power supply with power factor correction (PFC) is proposed in this paper. The power supply consists of a unipolar pulse high voltage generating unit, a PFC unit, and a driving circuit. By introducing a feedback clamping diode and a reverse current blocking diode in a flyback converter, repetitive nanosecond pulses are generated in the unipolar pulse high voltage generating unit. Because a discontinuous current mode strategy is adopted in the PFC unit and the driving signal is shared by the two units, a compact structure of the power supply is achieved, and a high PF is obtained. To validate the proposed pulsed power supply, an experimental setup is built for a DBD excimer lamp. The results show that the proposed power supply has the capability of not only providing a unipolar nanosecond pulse high voltage for the DBD excimer lamp but also achieving PF close to 1 and total harmonic distortion of less than 24%.

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Lomaev, M. I., V. F. Tarasenko, and A. V. Diatlov. "Cumulation of a high-current electron beam at nanosecond high-volyage discharge in a low-pressure diode." Izvestiya vysshikh uchebnykh zavedenii. Fizika, no. 6 (June 1, 2019): 68–71. http://dx.doi.org/10.17223/00213411/62/6/68.

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Beloplotov, Dmitry, Konstantin Savkin, Viktor Semin, and Dmitry Sorokin. "Magnesium Oxide and Magnesium Fluoride Nanopowders Produced in a Diffuse Nanosecond Discharge in Argon." Ceramics 6, no. 3 (2023): 1467–77. http://dx.doi.org/10.3390/ceramics6030090.

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The synthesis of the nanopowders of magnesium oxide and magnesium fluoride during the operation of a repetitive diffuse nanosecond discharge in argon at various pressures was performed. Nanosecond voltage pulses with an amplitude of −70 kV, a rise time of 0.7 ns, and a duration of 0.7 ns were applied across a point-to-plane gap of 2 mm in length. The pulse repetition rate was 60 Hz. The high-voltage pointed electrode was made of magnesium. A diffuse discharge cold plasma was formed under these conditions. Nanoparticles were produced as a result of an explosion of microprotrusions on the surface of the magnesium electrode duo to a high current density. Lines of magnesium atoms and ions were observed in the emission optical spectrum. Under the actions of the gas dynamics processes caused by the plasma channel expansion during the interpulse period, nanoparticles were deposited onto the surface of the grounded plane electrode and the side wall of the gas discharge chamber. The morphology, elemental, and phase composition of the powders were studied using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS).

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Lomaev, M. I., V. F. Tarasenko, and A. V. Dyatlov. "Cumulation of a High-Current Electron Beam During a Nanosecond High-Voltage Discharge in a Low-Pressure Diode." Russian Physics Journal 62, no. 6 (2019): 996–1000. http://dx.doi.org/10.1007/s11182-019-01806-9.

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Малініна, А. М., О. М. Малінін, О. К. Шуаібов, and В. В. Данило. "Parameters of plasma of high-current nanosecond discharge in air with small admixtures of copper vapor." Scientific Herald of Uzhhorod University.Series Physics 43 (June 30, 2018): 89–95. http://dx.doi.org/10.24144/2415-8038.2018.43.89-95.

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Rodrigo-Mor, Armando, Fabio A. Muñoz, and Luis Carlos Castro-Heredia. "Principles of Charge Estimation Methods Using High-Frequency Current Transformer Sensors in Partial Discharge Measurements." Sensors 20, no. 9 (2020): 2520. http://dx.doi.org/10.3390/s20092520.

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This paper describes a simplified model and a generic model of high-frequency current transformer (HFCT) sensors. By analyzing the models, a universal charge estimation method based on the double time integral of the measured voltage is inferred. The method is demonstrated to be valid irrespective of HFCT sensor, assuming that its transfer function can be modelled as a combination of real zeros and poles. This paper describes the mathematical foundation of the method and its particularities when applied to measure nanosecond current pulses. In practice, the applicability of the method is subjected to the characteristics and frequency response of the sensor and the current pulse duration. Therefore, a proposal to use the double time integral or the simple time integral of the measured voltage is described depending upon the sensor response. The procedures used to obtain the respective calibration constants based on the frequency response of the HFCT sensors are explained. Two examples, one using a HFCT sensor with a broadband flat frequency response and another using a HFCT sensor with a non-flat frequency response, are presented.

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Mursenkova, I., A. Ivanova, I. Ivanov, N. Sysoev, and A. Karimov. "High-Speed Flow Visualization by a Nanosecond Volume Discharge during Shock Wave Diffraction on an Obstacle." Scientific Visualization 15, no. 3 (2023): 40–49. http://dx.doi.org/10.26583/sv.15.3.05.

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We study the spatial structure of nonstationary inhomogeneous supersonic airflows as shock wave diffraction on an obstacle occurs in a shock tube of a rectangular cross section. The Mach numbers of shock waves were 2.7–4.4 at initial air pressures of 10–30 Torr. The supersonic flow in the discharge chamber was visualized by high-speed shadowgraphy and by the registration of radiation of combined volume discharge by photo camera and by ICCD camera. In experiments, a combined volume discharge with a current duration of ~ 500 ns was initiated 40–150 μs after the initial shock wave have passed an obstacle. It has been established that the radiation of the volume phase of discharge lasts 400–700 ns, and the displacement of the flow during this time does not exceed 0.6 mm. A correlation is established between the spatial distribution of discharge radiation and the low-density local areas determined as a result of two-dimensional Navier-Stokes based numerical simulation of the flow. As visualized by the glow of the discharge, the shape of the shock wave front is in good agreement with the results of shadowgraphy at different stages of diffraction and with the numerical simulation results.

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Deng, Zichen, Qi Yuan, Ran Chang, et al. "High voltage nanosecond pulse generator based on pseudospark switch and diode opening switch." Review of Scientific Instruments 94, no. 2 (2023): 024703. http://dx.doi.org/10.1063/5.0127505.

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With the development of technology, low-temperature plasma plays an increasingly important role in industrial applications. The industrial application of low-temperature plasma has the following requirements for plasma, high electron energy, low macroscopic temperature, and uniformity. Low-temperature plasma driven by nanosecond pulses reflects more significant advantages in these aspects compared to direct current plasma and alternating current plasma. In this paper, a simple topology is proposed, which is based on the pseudospark switch and the diode opening switch. A pulse generator is developed, which can eventually output pulses with an amplitude of 106 kV, a rise time of 15.5 ns, a pulse width of 46 ns, and a maximum repetition rate of 1 kHz on a 260 Ω resistive load. The pulse generator can successfully drive needle-plate discharge plasma in ambient air. It has excellent parameters, stability, compactness, and a long lifetime. The proposed topology may be helpful for nanosecond pulse generators with amplitude ranging from tens to hundreds of kilovolts, which could be widely used in industry.

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Starikovskiy, Andrey, Nickolay Aleksandrov, and Aleksandr Rakitin. "Plasma-assisted ignition and deflagration-to-detonation transition." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 370, no. 1960 (2012): 740–73. http://dx.doi.org/10.1098/rsta.2011.0344.

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Non-equilibrium plasma demonstrates great potential to control ultra-lean, ultra-fast, low-temperature flames and to become an extremely promising technology for a wide range of applications, including aviation gas turbine engines, piston engines, RAMjets, SCRAMjets and detonation initiation for pulsed detonation engines. The analysis of discharge processes shows that the discharge energy can be deposited into the desired internal degrees of freedom of molecules when varying the reduced electric field, E / n , at which the discharge is maintained. The amount of deposited energy is controlled by other discharge and gas parameters, including electric pulse duration, discharge current, gas number density, gas temperature, etc. As a rule, the dominant mechanism of the effect of non-equilibrium plasma on ignition and combustion is associated with the generation of active particles in the discharge plasma. For plasma-assisted ignition and combustion in mixtures containing air, the most promising active species are O atoms and, to a smaller extent, some other neutral atoms and radicals. These active particles are efficiently produced in high-voltage, nanosecond, pulse discharges owing to electron-impact dissociation of molecules and electron-impact excitation of N 2 electronic states, followed by collisional quenching of these states to dissociate the molecules. Mechanisms of deflagration-to-detonation transition (DDT) initiation by non-equilibrium plasma were analysed. For longitudinal discharges with a high power density in a plasma channel, two fast DDT mechanisms have been observed. When initiated by a spark or a transient discharge, the mixture ignited simultaneously over the volume of the discharge channel, producing a shock wave with a Mach number greater than 2 and a flame. A gradient mechanism of DDT similar to that proposed by Zeldovich has been observed experimentally under streamer initiation.

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Шевера, Ігор Васильович, Владислав Валерійович Данило, Золтан Тиборович Гомокі, Олександр Йосипович Миня, Олександр Камілович Шуаібов, and Василь Іванович Чигінь. "Characteristics of high current nanosecond discharge in the air above surface the copper sulfate solution in distilled water." Scientific Herald of Uzhhorod University.Series Physics 41 (June 1, 2017): 112–19. http://dx.doi.org/10.24144/2415-8038.2017.41.112-119.

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Baranov, Igor Y., and Andrey V. Koptev. "Mode-Locked CO Laser for Isotope Separation of Uranium Employing Condensation Repression." Advances in Optical Technologies 2010 (December 16, 2010): 1–6. http://dx.doi.org/10.1155/2010/693530.

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In the present work, we have suggested a technical solution of a CO laser facility for industrial separation of uranium used in the production of fuel for nuclear power plants. There has been used a method of laser isotope separation of uranium, employing condensation repression in a free jet. The laser operation with nanosecond pulse irradiation can provide acceptable efficiency in the separating unit and the high effective coefficient of the laser with the wavelength of 5.3 μm. Receiving a uniform RF discharge under medium pressure and high Mach numbers in the gas stream solves the problem of an electron beam and cryogenic cooler of CO lasers. The laser active medium is being cooled while it is expanding in the nozzle; a low-current RF discharge is similar to a non-self-sustained discharge. In the present work, we have developed a calculation model of optimization and have defined the parameters of a mode-locked CO laser with an RF discharge in the supersonic stream. The CO laser average power of 3 kW is sufficient for efficient industrial isotope separation of uranium at one facility.

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Vereshchagin, N. M., S. A. Kruglov, A. A. Serezhin, S. G. Shatilov, K. D. Agaltsov, and M. B. Pavlov. "Low-pressure gas-discharge current interrupters in a generator of high-voltage nanosecond pulses with an inductive energy storage." Instruments and Experimental Techniques 60, no. 6 (2017): 811–17. http://dx.doi.org/10.1134/s0020441217060124.

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Kozyrev, Andrey, and Victor Tarasenko. "Optimal Conditions for the Generation of Runaway Electrons in High-Pressure Gases." Plasma 7, no. 1 (2024): 201–32. http://dx.doi.org/10.3390/plasma7010013.

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Runaway electron (RAE) generation in high-pressure gases is an important physical phenomenon that significantly influences discharge shapes and properties of initiated plasma. The diffuse discharges formed due to RAEs in the air and other gases at atmospheric pressure find wide applications. In the present review, theoretical and experimental results that explain the reason for RAE occurrence at high pressures are analyzed, and recommendations are given for the implementation of conditions under which the runaway electron beam (RAEB) with the highest current can be obtained at atmospheric pressure. The experimental results were obtained using subnanosecond, nanosecond, and submicrosecond generators, including those specially developed for runaway electron generation. The RAEBs were recorded using oscilloscopes and collectors with picosecond time resolution. To theoretically describe the phenomenon of continuous electron acceleration, the method of physical kinetics was used based on the Boltzmann kinetic equation that takes into account the minimum but sufficient number of elementary processes, including shock gas ionization and elastic electron scattering. The results of modeling allowed the main factors to be established that control the RAE appearance, the most important of which is electron scattering on neutral atoms and/or molecules. Theoretical modeling has allowed the influence of various parameters (including the voltage, pressure, gas type, and geometrical characteristics of the discharge gap) to be taken into account. The results of the research presented here allow RAE accelerators with desirable parameters to be developed and the possibility of obtaining diffuse discharges to be accessed under various conditions. The review consists of the Introduction, five sections, the Conclusion, and the References.

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Sorokin, D. A., M. I. Lomaev, A. V. Dyatlov, and V. F. Tarasenko. "Time behavior of an electron beam current pulse in the axial and peripheral zones of an anode in vacuum and gas-filled diodes." Journal of Physics: Conference Series 2064, no. 1 (2021): 012031. http://dx.doi.org/10.1088/1742-6596/2064/1/012031.

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Abstract The study of the time behavior of a current pulse of an electron beam generated during a high-voltage nanosecond discharge in gas-filled and vacuum diodes has been carried out. As follows from the experimental results, in both cases, the distribution of the beam current density in the plane of a grounded anode is non-uniform. The highest beam current density is recorded in the axial part of the anode. It was established that in the case of a gas-filled diode, ~ 2 ns after the onset of the beam current pulse, its shape in the axial anode zone changes relative to that in the peripheral one. It is assumed that the most probable reason for this is the effect of compensation of the charge of the beam electrons by the positive charge of ions arising in the ionization process in the paraxial zone.

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Shuaibov, A. K., A. Y. Minya, A. A. Malinina, et al. "Characteristics and Parameters of Overstressed Nanosecond Discharge Plasma in Air between an Electrode from Aluminum and Electrode from Chalcopyrite (CuInSe2)." Elektronnaya Obrabotka Materialov 57, no. 5 (2021): 34–51. http://dx.doi.org/10.52577/eom.2021.57.5.34.

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The characteristics and parameters of an overstressed high-current discharge with a duration of 100–150 ns in air, which was ignited between an aluminum electrode and a chalcopyrite electrode (CuInSe2), are presented. The air pressure was 13.3 and 101.3 kPa. In the process of microexplosions of inhomogeneities on the working surfaces of electrodes in a strong electric field, aluminum vapors and chalcopyrite vapors were introduced into the interelectrode gap, which creates the prerequisites for the synthesis of thin films based on quaternary chalcopyrite – CuAlInSe2. The films synthesized from the products of electrode destruction were deposited on a quartz plate at a distance of 2–3 cm from the center of the discharge gap. The current and voltage pulses across the discharge gap of d = 1 mm, as well as the pulse energy input into the discharge, were investigated. The plasma emission spectra were studied, which made it possible to establish the main decay products of the chalcopyrite molecule and the energy states of atoms and singly charged ions of aluminum, copper and indium, which are formed in the discharge. The reference spectral lines of atoms and ions of aluminum, copper, and indium were established, which can be used to control the process of deposition of thin films of quaternary chalcopyrite. Thin films were synthesized from the degradation products of chalcopyrite molecules and aluminum vapors, which may have the composition of the quaternary chalcopyrite CuAlInSe2; the transmission spectra of the synthesized films in the spectral range of 200–800 nm were studied. By the method of numerical simulation of the plasma parameters of an overstressed nanosecond discharge based on aluminum and chalcopyrite vapors in air by solving the Boltzmann kinetic equation for the electron energy distribution function, the temperature and density of electrons, the specific power losses of the discharge for the main electronic processes and their rate constants depending on the value parameter E/N for plasma of vapor-gas mixtures based on air, aluminum vapor and ternary chalcopyrite were modulated.

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30

Li, Shuqi, Yunhu Liu, Hao Yuan, et al. "Generation of High-Density Pulsed Gas–Liquid Discharge Plasma Using Floating Electrode Configuration at Atmospheric Pressure." Applied Sciences 12, no. 17 (2022): 8895. http://dx.doi.org/10.3390/app12178895.

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In this paper, a high-density gas–liquid discharge plasma is obtained combined with nanosecond pulse voltage and a floating electrode. The discharge images, the waveforms of pulse voltage and discharge current, and the optical emission spectra are recorded. Gas temperature and electron density are calculated by the optical emission spectra of N2 (C3Πu → B3Πg) and the Stark broadening of Hα, respectively. The emission intensities of N2 (C3Πu → B3Πg), N2+ (B2Σ → X2Π), OH (A2Σ → X2Π), O (3p5P → 3s5S0), He (3d3D → 3p3P20), gas temperature, and electron density are acquired by optical emission spectra to discuss plasma characteristics varying with spatial distribution, discharge gap, and gas flow rate. The spatial distributions of discharge characteristics, including gas temperature, electron density, and emission intensities of N2 (C3Πu → B3Πg), N2+ (B2Σ → X2Π), OH (A2Σ → X2Π), O (3p5P → 3s5S0), and He (3d3D → 3p3P20), are presented. It is found that a high-density discharge plasma with the electron density of 2.2 × 1015 cm−3 and low gas temperature close to room temperature is generated. While setting the discharge gap distance at 10 mm, the discharge area over liquid surface has the largest diameter of 20 mm; under the same conditions, electron density is in the order of 1015 cm−3, and gas temperature is approximately 330 K. In addition, the discharge plasma characteristics are not kept consistent in the axial direction, in which the emission intensities of N2+ (B2Σ → X2Π), N2 (C3Πu → B3Πg), OH (A2Σ → X2Π), and gas temperature increased near the liquid surface. As the discharge gap is enlarged, the gas temperature increases, whereas the electron density remains almost constant. Moreover, as the gas flow rate was turned up, the electron density increased and the gas temperature was kept constant at 320 K.

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Oleksander, Shuiabov, Mynya Oleksander, Chyhin Vasyl, Grytsak Roksolana, and Malinina Antonina. "Features of High Current Nanosecond Discharge in Mixture of High Pressure CuInSe<sub>2 </sub> Chalkopyrite Vapor and Argon." Journal of Biomaterials 3, no. 2 (2019): 37. http://dx.doi.org/10.11648/j.jb.20190302.11.

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32

Ukraintseva, Tatyana V., Andrei S. Mazur, Ulyana M. Poberezhnaya, and Georgy G. Savenkov. "RESEARCH OF FACTORS FAVORING UNAUTHORIZED INITIATION OF ENERGY SATURATED MATERIALS." Bulletin of the Saint Petersburg State Institute of Technology (Technical University) 57 (2021): 10–14. http://dx.doi.org/10.36807/1998-9849-2020-57-83-10-14.

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The results of experimental studies on the initiation of compositions containing energy-saturated materials by high-current electron beams and electrodischarge plasma are presented. Experimental studies simulate the effects on energy-saturated materials of electromagnetic fields of natural and man-made origin. The threshold voltage of the electrical breakdown of the compositions during a high-voltage electric discharge was determined and the possibility of initiation of the compositions by high-current electron beams of nanosecond duration using a pulsed high-current electron accelerator GKVI-300 was studied. Four compositions were selected as objects of study: a composition based on potassium picrate, a composition containing ammonium perchlorate, a composition based on lead minium with zirconium and colloxylin additives, and ballistite composition SBK-3. It is shown in the work that the initiation of compositions by a high-current electron beam is potentially possible only for compositions with low ignition temperatures, ignition of compositions with high ignition temperatures is possible due to the introduction of a powdery nanoscale additive, particles of which have specific heat less than particles of an energy-saturated material, and ignition of ammonium perchlorate is possible only if the particles of the additive have lower thermal conductivity than the particles of perchlorate ammonium.

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Shen, Hongwei, Hao Yuan, Jianping Liang, et al. "Degradation of Pyraclostrobin in Water Using a Novel Hybrid Gas–Liquid Phase Discharge Reactor." Water 15, no. 8 (2023): 1562. http://dx.doi.org/10.3390/w15081562.

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In this paper, the hybrid gas–liquid discharge plasma can efficiently degrade pesticide residues in water driven by nanosecond pulse power, which can achieve the simultaneous discharge process in the liquid and gas phases. The relevant factors are systematically investigated, including the waveforms of discharge current and pulse voltage, discharge images, and optical emission spectra during the discharge process. The Stark broadening of Hα calculates the electron density. The effects of the pulse peak voltage and discharge time on the emission intensities of OH (A2∑ → X2∏), N2 (C3∏u → B3∏g), Hα, and O (3p5P → 3s5S0) are discussed in-depth by the optical emission spectra. The gas–liquid discharge plasma with an electron density of 7.14 × 1017 cm−3 was found. The emission intensities of OH (A2∑ → X2∏), N2 (C3∏u → B3∏g), Hα, and O (3p5P → 3s5S0) present the rising trend by increasing the pulse peak voltage and discharge time. In addition, pyraclostrobin is adopted as the research object to study the removal efficiency of pollutants. The results confirm that pyraclostrobin can be completely degraded after 10 min of plasma treatment with the pulse peak voltage of 28 kV, and the degradation rate and energy yield was 0.323 min−1, and 1.91 g/kWh, respectively. The intermediate products and the possible degradation mechanism of pyraclostrobin are further explored by combining the results of high-performance liquid chromatography–mass spectrometry (HPLC-MS/MS) and density functional theory (DFT), the developmental toxicity of the intermediate products was analyzed, which provided a scheme for the treatment of pesticide wastewater by gas–liquid discharge plasma technology.

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34

Shuaibov, A. K., A. I. Minya, R. V. Grytsak, et al. "Investigation of the conditions of synthesis of metal and chalcopyrite films from the degradation products of electrodes of an overstressed nanosecond discharge in argon and air." Physics and Chemistry of Solid State 21, no. 4 (2020): 669–79. http://dx.doi.org/10.15330/pcss.21.4.669-679.

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The characteristics of an overstressed bipolar discharge with a duration of 100-150 ns in argon and air, which was ignited between copper electrodes in argon, and also between an aluminum electrode and a chalcopyrite (CuInSe2) electrode in air, are presented. In the process of microexplosions of inhomogeneities on the working surfaces of the electrodes in a strong electric field, the vapor of copper, aluminum, and vapor of ternary chalcopyrite are introduced into the interelectrode gap. This creates the prerequisites for the synthesis of thin copper films and the synthesis of films based on quaternary chalcopyrite - CuAlInSe2, which can be deposited on a quartz plate installed near the center of the discharge gap. The optical characteristics of the plasma, as well as voltage pulses across the discharge gap of d = 1–2 mm, current pulses, and pulsed energy contributions to the discharge, have been investigated using emission spectroscopy with a high time resolution. The plasma emission spectra were thoroughly studied, which made it possible to establish the main decay products of the chalcopyrite molecule and the energy states of atoms and singly charged ions of aluminum, copper, and indium, which are formed in the discharge.

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35

Remigy, A., X. Aubert, S. Prasanna, et al. "Absolute N-atom density measurement in an Ar/N₂ micro-hollow cathode discharge jet by means of ns-two-photon absorption laser-induced fluorescence." Physics of Plasmas 29, no. 11 (2022): 113508. http://dx.doi.org/10.1063/5.0110318.

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In this work, nanosecond two-photon absorption laser-induced fluorescence (TALIF) is used to probe the absolute density of nitrogen atoms in a plasma generated using a micro-hollow cathode discharge (MHCD). The MHCD is operated in the normal regime, and the plasma is ignited in an Ar/N2 gas mixture. First, we study a MHCD configuration having the same pressure (50 mbar) on both sides of the electrodes. A good agreement is found between the density of N atoms measured using TALIF in this work and previous measurements using vacuum ultraviolet Fourier transform absorption spectroscopy. Then, we introduce a pressure differential between the two electrodes of the MHCD, creating a plasma jet. The influence of the discharge current, the percentage of N2 in the gas mixture, and pressures on both sides of the MHCD is studied. The current has a small impact on the N-atom density. Furthermore, an optimal N-atom density is found at around 95% of N2 in the discharge. Finally, we demonstrate that the pressure has a different impact depending on the side of the MHCD: the density of N atoms is much more sensitive to the change of the pressure in the low-pressure side when compared to the pressure change in the high-pressure side. This could be due to several competing phenomena: gas residence time in the cathodic region, recirculation, or recombination of the N atoms at the wall. This study contributes to the optimization of MHCD as an efficient N-atom source for material deposition applications.

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36

Wen, Ruihu, Ping Li, and Haibin Wang. "Investigation of the Distribution Problem in the Operating State of an Electromagnetic Railgun: Radio Fuse Disturbance, Field Characteristics, and Susceptible." Electronics 12, no. 13 (2023): 2914. http://dx.doi.org/10.3390/electronics12132914.

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The purpose of this article is to analyze the front door coupling effect that may occur in the projectile receiver due to the discharge pulse radiation in electromagnetic railguns, and to simulate the discharge pulse interference. This phenomenon will have an impact on the launch of the projectile, causing its fuse to be disturbed, ultimately affecting the weapon performance of the electromagnetic railgun. Discharge refers to when the armature carrying the projectile is fired out of the chamber, and the armature connected between the two rails detaches, causing a circuit break in the electrical circuit during the operation of the electromagnetic railgun. The current flowing through the armature is disturbed, causing an instantaneous high voltage to penetrate the air gap between the two rails, generating nanosecond pulse width discharge voltage pulse radiation, with a spectrum of up to tens of megahertz. In this paper, we establish a receiving antenna model on the projectile, which is essentially a horn antenna, receiving electromagnetic pulses from the discharge process, and coupling the pulse interference through its front door. During the analysis and calculation, we established an antenna receiver model located in the C-band with a frequency of 6 GHz for simulation, analyzed and calculated the actual interference loaded on the projectile after front door coupling, and verified the correctness of the simulation settings and results by comparing with the literature. Finally, we found that because the main energy spectrum of the pulse is at MHz level, when the front door of the C-band horn antenna is coupled, the standing wave ratio of the antenna is very large and the gain is very small, so the pulse interference is filtered, which can make the interference finally loaded on the projectile insufficient to affect the normal operation of the projectile. At the same time, it is recommended to add an RF filter to the receiving channel to further enhance anti-interference ability, so as to ultimately enable the electromagnetic railgun to function properly.

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37

Beloplotov, Dmitry, Dmitry Sorokin, and Victor Tarasenko. "High-Voltage Nanosecond Discharge as a Means of Fast Energy Switching." Energies 14, no. 24 (2021): 8449. http://dx.doi.org/10.3390/en14248449.

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The formation of a nanosecond discharge with the use of a Hamamatsu streak-camera and with simultaneously wideband (10 GHz) measurement of voltage and displacement current caused by a streamer in one pulse has been studied. Nanosecond voltage pulses of various amplitudes (16, 20, and 27 kV) were applied across a point-to-plane gap (8.5 mm) filled with air at various pressures (13, 25, 50, 100, and 200 kPa). It was found that the voltage across the gap drops as soon as a streamer appears in the vicinity of the pointed electrode. At the same time, a pre-breakdown current begins to flow. The magnitude of the pre-breakdown current, as well as the voltage drop, is determined by the rate of formation of dense plasma and, accordingly, by the rate of redistribution of the electric field in the gap. The streamer velocity determines the rise time and amplitude of the current. The higher the streamer velocity, the shorter the rise time and the higher the amplitude of the pre-breakdown current. The propagation of a backward and third ionization waves was observed both with the streak camera and by measuring the displacement current. As they propagate, the discharge current increases to its amplitude value.

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38

Sorokin, D. A., V. F. Tarasenko, Cheng Zhang, et al. "X-ray radiation and runaway electron beams generated during discharges in atmospheric-pressure air at rise times of voltage pulse of 500 and 50 ns." Laser and Particle Beams 36, no. 2 (2018): 186–94. http://dx.doi.org/10.1017/s0263034618000150.

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AbstractThe parameters of X-ray radiation and runaway electron beams (RAEBs) generated at long-pulse discharges in atmospheric-pressure air were investigated. In the experiments, high-voltage pulses with the rise times of 500 and 50 ns were applied to an interelectrode gap. The gap geometry provided non-uniform distribution of the electric field strength. It was founded that at the voltage pulse rise time of 500 ns and the maximum breakdown voltage Um for 1 cm-length gap, a duration [full width at half maximum (FWHM)] of a RAEB current pulse shrinks to 0.1 ns. A decrease in the breakdown voltage under conditions of a diffuse discharge leads to an increase in the FWHM duration of the electron beam current pulse up to several nanoseconds. It was shown that when the rise time of the voltage pulse is of 500 ns and the diffuse discharge occurs in the gap, the FWHM duration of the X-ray radiation pulse can reach ≈100 ns. It was established that at a pulse-periodic diffuse discharge fed by high-voltage pulses with the rise time of 50 ns, an energy of X-ray quanta and their number increase with increasing breakdown voltage. Wherein the parameter Um/pd is saved.

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39

Karelin, V. I., and A. A. Tren’kin. "High-energy electrons in nanosecond high-voltage discharges developing in the regime of microstructured current channels." Technical Physics Letters 35, no. 5 (2009): 407–9. http://dx.doi.org/10.1134/s106378500905006x.

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40

Dubinov, A. E., and J. P. Kozhayeva. "Transparent Hydrogel Electrodes as a New Class of Electrodes for High-Current Nanosecond Atmospheric-Pressure Discharges." High Energy Chemistry 53, no. 6 (2019): 425–28. http://dx.doi.org/10.1134/s0018143919060031.

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41

Karelin, V. I., A. A. Trenkin, and I. G. Fedoseev. "Dynamics of the microstructure of current channels and the generation of high-energy electrons in nanosecond discharges in air." Physics of Atomic Nuclei 78, no. 12 (2015): 1440–45. http://dx.doi.org/10.1134/s1063778815120133.

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42

He, Shaoyin, Xiangyu Chen, Bohao Zhang, and Liang Song. "Development of a Multi-Channel Ultra-Wideband Electromagnetic Transient Measurement System." Sensors 25, no. 4 (2025): 1159. https://doi.org/10.3390/s25041159.

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In complex electromagnetic environments, such as substations, converter stations in power systems, and the compartments of aircraft, trains, and automobiles, electromagnetic immunity testing is crucial. It requires that the electric field sensor has features such as a large dynamic measurement range (amplitude from hundreds of V/m to tens of kV/m), a fast response speed (response time in the order of nanoseconds or sub-nanoseconds), a wide test bandwidth (DC to 1 GHz even above), miniaturization, and robustness to strong electromagnetic interference. This paper introduces a multi-channel, ultra-wideband transient electric field measurement system. The system’s analog bandwidth covers the spectrum from DC and a power frequency of 50 Hz to partial discharge signals, from DC to 1.65 GHz, with a storage depth of 2 GB (expandable). It overcomes issues related to the instability, insufficient bandwidth, and lack of accuracy of optical fibers in analog signal transmission by using front-end digital sampling based on field-programmable gate array (FPGA) technology and transmitting digital signals via optical fibers. This approach is effectively applicable to measurements in strong electromagnetic environments. Additionally, the system can simultaneously access four channels of signals, with synchronization timing reaching 300 picoseconds, can be connected to voltage and current sensors simultaneously, and the front-end sensor can be flexibly replaced. The performance of the system is verified by means of a disconnect switch operation and steady state test in an HVDC converter station. It is effectively applicable in scenarios such as the online monitoring of transient electromagnetic environments in high-voltage power equipment, fault diagnosis, and the precise localization of radiation sources such as partial discharge or intentional electromagnetic interference (IEMI).

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43

Chen, Zhiqiang, Jinru Sun, Ziyi Dong, et al. "Failure behavior of dielectric films for peaking capacitor subjected to surface flashover under nanosecond pulses." AIP Advances 13, no. 12 (2023). http://dx.doi.org/10.1063/5.0177780.

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The flashover failure and damage of polypropylene (PP) and polyester (PET) films under nanosecond current pulses were experimentally investigated. A nanosecond pulse current test platform was established to study the flashover characteristics, performance degradation, and structural damage of dielectric films under repeated nanosecond current pulses. The accumulation and emission of surface charge influenced by field distortion and trap distribution were analyzed to clarify the mechanism by which the flashover voltage increases linearly with gas pressure at low pressure and saturates at high pressure. The significant effects of pulse energy, gas pressure, and discharge gap on film damage behavior were investigated. The damage pattern of PP and PET films includes surface deformation, reduced flash-voltage tolerance, molecular chain breakage, and group shedding. The damage of PP films is manifested as fine furrows, while PET corresponds to mountainous bumps. With the increasing number of discharges, the breakdown voltage of PP films decreased significantly, while the flash tolerance performance of PET films was more stable. Under the conditions of high pulse current amplitude, small discharge gap, and low air pressure, the damage degree of the film intensifies, which is characterized by severe destruction to the molecular structure and a significant decrease in flashover withstand voltage. Polymer films, flashover, nanosecond current pulses; performance degradation; microstructural damage.

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44

Hoffer, Petr, Vaclav Prukner, Garima Arora, and Milan Šimek. "High-speed imaging reveals the dynamics of the initiation and subsequent evolution of a nanosecond discharge propagating along the air-water interface." Plasma Sources Science and Technology, September 13, 2023. http://dx.doi.org/10.1088/1361-6595/acf955.

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Abstract Nanosecond DBD-like discharge in coplanar electrode configuration propagating along water-air interface is an efficient source of reactive species to produce plasma-activated water. In this letter, we report on mechanism of the discharge onset as well as on further developments during hundreds of nanoseconds. We combined ultrafast optical imaging with electrical characteristics to capture basic morphological imprints of individual discharge phases occurring during a single discharge event with high temporal resolution. We show that during the first nanoseconds, a diffuse bi-directional ionizing avalanche expands over the liquid surface at high speed (>5×105 m/s). Later, discrete plasma filaments form from the diffuse plasma due to an ionization instability. The filaments, during their subsequent elongation (~2×105 m/s), retain the diffuse plasma at both ends. The filaments re-ignite in the same positions on the liquid surface over several successive (mainly capacitive) current pulses (~1 μs apart), which resulted from discontinuities in the driving voltage.

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45

Gao, Shuhan, Xucheng Wang, and Yuantao Zhang. "Modeling study on different discharge characteristics in pulsed discharges with and without barriers on electrodes." Plasma Science and Technology, December 2, 2022. http://dx.doi.org/10.1088/2058-6272/aca86d.

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Abstract High-pressure Nanosecond Pulsed Discharge (NPD) has attracted an increasing attention in recent years due to the widely potential applications. In this study, a barrier-free NPD in pure helium plasma at 120 Torr was numerically investigated by a one-dimensional self-consistent fluid model, and its Current-Voltage Characteristics (CVCs) show very dierent behaviors from those in pulsed Dielectric Barrier Discharges (DBDs), which indicates entirely distinctive discharge evolution in pulsed discharges with or without barriers on electrodes. Without the control of barriers, the computational data suggest that the discharge current increases very sharply during the plateau phase of the pulsed voltage and reaches the peak value approximately at the instant when the pulsed voltage starts to drop, together with a gradual reduction in the sheath thickness and an increase in electric field in sheath region, which is in well accordance with the experimental observations. By increasing the voltage plateau width and repetition frequency, the discharge current density from the simulation can be substantially enhanced, which cannot be observed in the conventional pulsed DBDs, and the spatial distributions of the electric field and charged particles are given to unravel the underlying physics. From the computational data, the distinctive discharge characteristics in the barrier-free NPDs are deeply understood, and could be further optimized by tailoring the waveforms of pulsed voltage to obtain the desirable plasmas for applications.

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Jiang, Chunqi, Akash Chandrashekhar Dhotre, Meimei Lai, Sayan Biswas, James Richard MacDonald, and Isaac W. Ekoto. "On the modes of nanosecond pulsed plasmas for combustion ignition of quiescent CH4-air mixtures." Journal of Physics D: Applied Physics, July 29, 2024. http://dx.doi.org/10.1088/1361-6463/ad6876.

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Abstract The effect of transient plasma modes on ignition kernel development are discussed here for a quiescent CH4-air combustion model system. A 10-ns high-voltage pulse was applied to a pin-to-pin electrode in lean atmospheric fuel-air mixtures at room temperature. High-impedance streamer, transient spark and low-impedance spark discharges were identified based on pulse waveforms of voltage and current. A sustained ignition kernel expansion was observed when the plasma discharge transitioned into a transient spark or spark discharge. The minimum ignition energy was obtained at the transient spark mode, which has less than a third of the energy or Coulomb transfer compared to the low-impedance spark. Employing repetitive 10-pulse sequence at 10 kHz, the lean-fuel limit was extended from an equivalence ratio of 0.6 for the single pulse ignition to 0.5. The use of repetitive pulses also allowed streamer breakdown or spark initiation to occur at a lower voltage.&#xD;

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47

Ivanova, A., I. Mursenkova, I. Kryukov, I. Ivanov, and I. Znamenskaya. "Diffracted shock wave propagation in a pulsed volume discharge plasma." Physics of Fluids 37, no. 3 (2025). https://doi.org/10.1063/5.0258844.

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The paper presents the results of experimental and numerical studies of the interaction of a nanosecond combined volume discharge and diffracted shock waves in air at Mach numbers ranging from 2.20 to 4.40. The spatial and temporal characteristics of the discharge were determined by analyzing the current waveforms, photographing the discharge glow, and imaging the discharge radiation with nanosecond resolution. The gasdynamic flow in the test section, which had transparent sidewalls, was visualized using the direct shadowgraph technique and recorded by a high-speed video camera operating at up to 525 000 fps. The experiments demonstrated changes in the dynamics of the shock wave configuration as it moved through the plasma region. Numerical simulations were performed based on the Navier–Stokes equations for viscous compressible gas. The power and dynamics of the energy deposition were varied to compare with the experimental flow patterns. The electrical energy of the discharge converted into heat was estimated to range from 0.12 to 0.20 J for the volumetric region and from 0.23 to 0.35 J for the areas of surface energy input. The obtained results help clarify the mechanism of influence of the pulsed energy deposition on supersonic flow with consideration of relaxation processes in the plasma. In general, the change in shock wave flow resulting from the interaction of shock waves with plasma regions is important when considering ways to control high-speed flows.

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Rataj, Raphael, Matthias Werneburg, Harald Below, and Juergen F. Kolb. "Hydrogen peroxide production of underwater nanosecond-pulsed streamer discharges with respect to pulse parameters and associated discharge characteristics." Plasma Sources Science and Technology, September 22, 2022. http://dx.doi.org/10.1088/1361-6595/ac942a.

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Abstract Pulsed streamer discharges submerged in water have demonstrated potential in a number of applications. Especially the generation of discharges by short high-voltage pulses in the nanosecond range has been found to offer advantages with respect to efficacies and efficiencies. The exploited plasma chemistry generally relies on the initial production of short-lived species, e.g. hydroxyl radicals. Since the diagnostic of these transient species is not readily possible, a quantification of hydrogen peroxide provides an adequate assessment of underlying reactions. These conceivably depend on the characteristics of the high-voltage pulses, such as pulse duration, pulse amplitude, as well as pulse steepness. A novel electrochemical flow-injection system was used to relate these parameters to hydrogen peroxide concentrations. Accordingly, the accumulated hydrogen peroxide production for streamer discharges ignited in deionized water was investigated for pulse durations of 100ns and 300ns, pulse amplitudes between 54kV and 64kV, and pulse rise times from 16ns to 31ns. An independent control of the individual pulse parameters was enabled by providing the high-voltage pulses with a Blumlein line. Applied voltage, discharge current, optical light emission and time-integrated images were recorded for each individual discharge to determine dissipated energy, inception statistic, discharge expansion and the lifetime of a discharge. Pulse steepness did not affect the hydrogen peroxide production rate, but an increase in amplitude of 10kV for 100-ns pulses nearly doubled the rate to (0.19±0.01)mol·l−1·s−1, which was overall the highest determined rate. The energy efficiency did not change with pulse amplitude, but was sensitive to pulse duration. Notably, production rate and efficiency doubled when the pulse duration decreased from 300ns to 100ns, resulting in the best peroxide production efficiency of (9.2±0.9)g·kWh−1. The detailed analysis revealed that the hydrogen peroxide production rate could be described by the energy dissipation in a representative single streamer. The production efficiency was affected by the corresponding discharge volume, which was comprised by the collective volume of all filaments. Hence, dissipating more energy in a filament resulted in an increased production rate, while increasing the relative volume of the discharge compared to its propagation time increased the energy efficiency.

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Okamoto, Tatsuki, and Hiroaki Uehara. "Nanosecond Partial Discharge Current Waveforms with Polyethylene Naphthalate Films on IEC(b) Electrode." IEEJ Transactions on Electrical and Electronic Engineering, May 2024. http://dx.doi.org/10.1002/tee.24092.

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The polyethylene naphthalate (PEN) film has been widely applied as a heat‐resistant thin insulation film and sensor film. For the safe and long application of the film in various products, one significant characteristic is the partial discharge (PD) resistivity. In this study, a well‐known IEC(b) electrode is used to measure PD characteristics such as the maximum partial discharge, qmax and fast PD current waveforms at AC peak voltages of 1–3 kVp and 50–1000 Hz over PEN films with thicknesses of 75, 50, or 25 μm. All experiments are conducted at room temperature of ~20 °C. The positive PD current is defined as the current flowing from a high‐voltage electrode to a ground electrode. The positive and negative qmax increased rapidly with the applied voltage increase but remained almost the same for the applied voltage frequency changes. The PD current duration time was less than 40 ns for the positive current and 30 ns for the negative current at all voltages, frequencies, and film thicknesses. It was deduced that the positive current peak magnitude was approximately twice of the negative one at all applied voltages, frequencies, and film thicknesses. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

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50

Parkevich, E. V., K. V. Shpakov, I. S. Baidin, et al. "Temporal map of electromagnetic emissions produced by laboratory atmospheric discharges." Journal of Applied Physics 136, no. 17 (2024). http://dx.doi.org/10.1063/5.0231084.

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We exhaustively investigate the temporal correlations between the ultrahigh-frequency (of the order of 1–6 GHz), very high-frequency (of the order of 10–100 MHz), and x-ray (photons with energies from 5 keV to 1 MeV) emissions together with the optical emissions in the near-infrared (within 700–1100 nm) and near-ultraviolet (within 300–400 nm) wavelength regions. The emissions are produced by a laboratory atmospheric discharge developing in an 55 cm air gap at voltages up to 1 MV. When registering various electromagnetic emissions, the discharge current and voltage are measured, as well as nanosecond imaging of the discharge evolution in its own glow is performed. The spatiotemporal localization of the discharge regions associated with the x-ray generation is carried out by employing the group of fast scintillation detectors, and the evolution of plasma structures during the x-ray generation is traced. A chronological map is constructed providing an in-depth understanding of the temporal character and correlations of various electromagnetic emissions. The map allows one to analyze fast ionization processes occurring in the gas-discharge medium and triggering the generation of the corresponding emissions. The generation mechanisms of the considered emissions in an extended high-voltage discharge are discussed. The findings can be helpful in revealing the sources of various electromagnetic emissions accompanying the formation of laboratory and atmospheric discharges.

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Journal articles on the topic 'High-current nanosecond discharge'

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