Inductive Discharge Research Articles

Two-Dimensional Thomson Model of a High-Frequency Induction Discharge of Finite Length

Two-Dimensional Thomson Model of a High-Frequency Induction Discharge of Finite Length

Radiofrequency Diagnostic of the Decaying Plasma in the “Gigantic” Coaxial Line at the Large Plasma Device

At the large-scale Krot facility (Gaponov-Grekhov Institute of Applied Physics of the Russian Academy of Sciences), a new device was developed for laboratory simulations of the effects of the interaction of ultrawideband electromagnetic pulses with the partially ionized atmosphere and ionosphere: the “gigantic” coaxial line with a length of 10 m and diameter of 1.4 m that is filled by the decaying plasma of the inductive discharge. Two radiofrequency methods of wave diagnostics used in the device are described, the cutoff method and the wave interferometer, which can be used to determine the electron density of the plasma in the line in a wide range of values, Ne = 107–1011 cm–3. The measurement results are compared with the values obtained by the contact diagnostic, a probe with a microwave resonator. The interferometric method is implemented taking into account the nonuniform distribution of plasma density both along and across the transmission line, which, in the working range of pulsed and continuous diagnostic signals, is an oversized waveguide. The specific features of application and the limitations of the contact (probe) and contactless (wave) methods of diagnostics are discussed, taking into account the nonuniform plasma distribution in the coaxial line and the specific features of its construction.

Experimental studies of H2/Ar plasma in a cylindrical inductive discharge with an expansion region

Abstract The electrical parameters of H2/Ar plasma in a cylindrical inductive discharge with an expansion region are investigated by a Langmuir probe, where Ar fractions range from 0% to 100%. The influence of gas composition and pressure on electron density, the effective electron temperature and the electron energy probability functions (EEPFs) at different spatial positions are present. In driver region, with the introduction of a small amount of Ar at 0.3 Pa, there is a rapid increase in electron density accompanied by a decrease in the effective electron temperature. Additionally, the shape of the EEPF transitions from a three-temperature distribution to a bi-Maxwellian distribution due to an increase in electron–electron collision. However, this phenomenon resulting from the changes in gas composition vanishes at 5 Pa due to the prior depletion of energetic electrons caused by the increase in pressure during hydrogen discharge. The EEPFs for the total energy in expansion region is coincident to these in the driver region at 0.3 Pa, as do the patterns of electron density variation between these two regions for differing Ar fractions. At 5 Pa, as the discharge transitions from H2 to Ar, the EEPFs evolved from a bi-Maxwellian distribution with pronounced low energy electrons to a Maxwellian distribution in expansion region. This evolve may be attributed to a reduction in molecular vibrational excitation reactions of electrons during transport and the transition from localized electron dynamics in hydrogen discharge to non-localized electron dynamics in argon discharge. In order to validate the experimental results, we use the COMSOL simulation software to calculate electrical parameters under the same conditions. The evolution and spatial distribution of the electrical parameters of the simulation results agree well with the trend of the experimental results.

A novel multi-spot structure for joining aluminum and steel dissimilar thin-walled tubes by magnetic pulse crimping

Lightweight manufacture for dissimilar thin-walled tube structures without additional liner support has always been a challenge. A novel magnetic pulse multi-spot joining structure was proposed for the non-weight gain mechanical connection of 6061 aluminum to SPCC (Steel Plate Cold-rolled Common) steel thin-walled tubes. Mechanical properties, microscopic features, and joining mechanism of the magnetic pulse crimping (MPC) joints were explored based on simulation and experiments. Under the geometric conditions of flyer tube with an outer diameter of 30 mm and a thickness of 1 mm, the optimal preformed groove depth and discharge energy for the MPC joints were 2 mm and 16 kJ, respectively. The corresponding maximum tensile and torsional strength were 10.6 kN and 131.2 N m, respectively. The corresponding relative thinning rate of aluminum outer tube was 13 %. The failure forms of the MPC joints were all pull out and torsion out failures. During the high-speed joining of aluminum tube to steel tube, stress concentration phenomena occurred successively at the circumferential bottom fillet, axial bottom fillet, and axial upper edge of the groove. This was due to a certain height difference between the circumferential and axial directions of the groove. It was related to induction distance, discharge energy, skin effect, proximity effect, and tip effect in the coupled field. The yielding and instability of the groove in the steel inner tube would lead to a decrease in the fitting area of the aluminum outer tube filled groove and the relative thinning rate of the aluminum outer tube. This caused a decrease in the mechanical interlocking force at the groove, which was detrimental to the mechanical properties of the MPC joints. This article provides a new approach and data support for the lightweight manufacture of dissimilar thin-walled tube structures.

Frequency Dependence of the Parameters of the Inductive RF Discharge Located in the Low-Value Magnetic Field

In this work, we carried out studies of the properties of an inductive RF discharge placed in a magnetic field with an induction of less than 70 G at frequencies of 2, 4 and 13.56 MHz. Experiments have shown that when operating at frequencies of 2 and 4 MHz at low powers of the RF generator, the range of existence of the discharge is limited by large magnetic fields. The efficiency of RF power input η non-monotonically depends on the magnitude of the magnetic field. The position of the main maximum η shifts to the region of higher B with increasing frequency, power of the RF generator and argon pressure, and at the same time the maximum broadens. An increase in frequency, power and argon pressure is accompanied by an increase in the absolute values of η. When operating at a frequency of 4 MHz, in addition to the main maximum η, a local maximum appears in the region B 35–70 G. With increasing pressure, a shift in the position of the local maximum and its smoothing is observed. Comparison of experimental data with calculated data allows us to conclude that the local maximum of plasma density observed at weak magnetic fields is associated with resonant excitation of waves in the plasma source. At a frequency of 2 MHz, the excited wave is close to a transverse helicon, and at a frequency of 13.56 MHz, its properties approach the Trivelpiece–Gold wave.

Penning Neon Laser Pumped by a Pulsed Inductive Longitudinal Discharge

Penning Neon Laser Pumped by a Pulsed Inductive Longitudinal Discharge

Selection of Dust Particles in Radio Frequency Inductive Discharge

Selection of Dust Particles in Radio Frequency Inductive Discharge

Three-terminal high-output triboelectric nanogenerator to achieve alternating current/direct current collaborative output by coupling three-dimensional porous structure, triboelectrification and corona discharge

Nowadays, the comprehensive consideration of output performance, durability, and industrial environmental recycling has been the focus of triboelectric nanogenerator (TENG) research in recent years. Herein, the melamine formaldehyde (MF) foam with the feature of three-dimensional porous structure, soft contact and eco-friendly is used to design a novel three-terminal high-output TENG (TH-TENG) to efficiently harvest rotating mechanical energy based on the coupling of electrostatic induction, triboelectrification and corona discharge. The simplified sliding TENG model has been demonstrated to have excellent electrical output of 532.81 μA m−2, with the outstanding resistance to heat and humidity of the output for maintaining 95.1 % and 82.1 % under the condition of 40 ℃ and 60 % RH, 20 ℃ and 80 % RH after 100 k cycles, respectively. Furthermore, the TH-TENG achieves efficient collaborative output of DC and AC through persistent directional movement and reciprocating movement with alternant connection of electrodes, where the upper-sided and lower-sided TENGs achieve DC with power density of 3.54 and 4.97 W m−3 Hz−1, and middle-sided TENG achieves AC with power density of 0.66 W m−3 Hz−1, respectively. The TH-TENG can drive 2540 LEDs and 8 incandescent lamps, and continuously power 36 hygrothermographs in parallel for smart farm. This work has enriched charge density enhancement strategy through the industrial recyclable MF foam.

A global plasma and surface model of hydrogen/methane inductively coupled discharge to analyze hydrocarbon plasma–surface interactions in extreme-ultraviolet lithography machines

Hydrocarbon contamination is associated with light transmission losses in modern lithography machines, which contain extreme-ultraviolet-induced plasma. A volume-averaged global and deposition/etch surface model of a reference hydrogen/methane inductive discharge is developed to investigate the plasma–surface interactions. The simulation results are validated against a wide variety of experiments and verified with respect to multiple sets of computational data. The deposition rate is calculated for a variation in methane impurity (10–10 000 ppm), power, pressure, and net mass flow. The simulations conclude that the hydrocarbon plasma deposition can be minimized by reducing methane impurity and excluding solid organic structures.

Effects of using nanosecond repetitively pulsed discharge and turbulent jet ignition on internal combustion engine performance

Robust ignition of hard-to-ignite fuels is essential for future spark ignited internal combustion engines, particularly for introducing efficiency-enhancing diesel-like process parameters like air excess or high amounts of exhaust gas recirculation (EGR). On the one hand, novel plasma-based ignition systems like Nanosecond Repetitively Pulsed Discharge (NRPD) are promising in extending the ignition limits and the early flame development speed. On the other hand, Turbulent Jet Ignition is effective for shortening the combustion duration and decreasing the unburned hydrocarbon emissions.This article investigates experimentally the combination of NRPD ignition and TJI. The aim is to use a technology for robust inflammation (NRPD) in combination with a technology for fast combustion of the bulk charge (TJI). For this purpose, a turbocharged light-duty four-cylinder engine operated with natural gas is used. The engine can be fitted with a classical Open Chamber (OC) spark plug or with Pre-Chambers (PC). The PCs can be filled uniquely with fuel and air coming from the Main Chamber (MC) (“passive PC”), or additional fuel can be added to the PCs (“active PC”). The air-to-fuel ratio and EGR rate can be freely controlled. Five different combustion strategies are investigated with NRPD ignition and compared against an inductive discharge ignition system. The combustion strategies are passive PC with air and EGR dilution, active PC with air dilution, and Open Chamber (OC) with air and EGR dilution. HRR evaluations and a loss analyses are performed to interpret the results.Despite the faster inflammation present with NRPD ignition, similar peak efficiencies and emissions are reached in OC configuration using the inductive discharge and NRPD ignition systems, which are achieved by varying air-to-fuel ratios (AFR) and EGR rates. Above dilution levels for peak efficiency, the efficiency using NRPD ignition decreases at a slower pace and tolerates higher AFR and EGR rates, thanks to a more complete and shorter combustion.For the PC experiments using NRPD ignition, an efficiency increases and a reduction of emissions compared to inductive discharge ignition are present for the investigated AFR and EGR rates for both active and passive PC operations. The efficiency increase is present due to a stronger pre-chamber discharge and thanks to a faster end phase of combustion. Actively fueling the PC results in faster and more complete combustion that is overcompensated by the increased wall heat losses, reducing the overall efficiency. The results show that passive PC with NRPD ignition may be an ideal ignition concept that maximizes engine efficiency and minimizes emissions.

Charge Accumulation Effect Enabled by a Bioinspired Self‐lubricating Triboelectric Nanogenerator for Both High Average Power Density and Long Durability

AbstractRecently through the synergetic utilization of triboelectrification, electrostatic induction, and electrostatic discharge, a novel dual‐functional triboelectric nanogenerator (DF‐TENG) has been developed, which can not only generate a motion‐responsible alternating current/ direct current output but also provide a higher performance compared to traditional TENGs. However, further improvements in performance and lifespan are crucial and remain challenging for the future large‐scale application of this new‐type TENG. Herein, a novel bioinspired self‐lubricating prototype is presented (BS‐TENG), which employs a porous polyurethane (PU) matrix impregnated with a low‐viscosity dielectric lubricant. In response to external mechanical stimuli, the BS‐TENG can “secrete” pre‐stored lubricant to partially fill micro‐gaps between tribo‐layers, thus forming self‐lubrication. This self‐lubricating mechanism not only elevates the electrostatic discharge threshold between tribo‐layers to maximize charge accumulation, thereby facilitating efficient energy release through electrostatic discharge for enhanced power output, but also significantly reduces material abrasion and realizes superior output durability. Benefiting from this effect, the BS‐TENG delivers an average power density of up to 4.6 W m−2, with extraordinary stability to retain 99% of its initial output even after over 60 000 cycles. This work provides a straightforward and effective strategy for realizing high‐performance and long‐stability TENGs, paving the way for their practical applications.

Comparative observation of the effectiveness and safety of remimazolam besylate versus dexmedetomidine in gastrointestinal surgery in obese patients.

Surgery for obese patients carries a higher risk of anesthesia complications compared with surgery for nonobese patients. Thus, a safe and effective anesthesia strategy is necessary to improve the medical experience of such patients and ensure their safety. To compared the effectiveness and safety of remimazolam besylate versus dexmedetomidine (DEX) in gastrointestinal surgery in obese patients. The study cohort included 60 obese patients undergoing gastrointestinal surgery between July 2021 and April 2023, comprising 30 patients who received DEX intervention (control group) and 30 patients who received remimazolam besylate intervention (research group). Heart rate (HR), respiratory rate (RR), mean arterial pressure (MAP), blood oxygen saturation (SpO2), safety (nausea and vomiting, bradycardia, hypotension, and apnea), anesthesia and examination indices [induction time, anesthesia recovery time, and postanesthesia care unit (PACU) discharge time], sedation effect (Ramsay Sedation Scale), and postoperative pain visual analog scale were comparatively analyzed before anesthesia (T0), during anesthesia (T1), and after anesthesia (T2). At T1, the research group showed significantly smaller changes in HR, RR, MAP, and SpO2 than the control group, with a significantly lower adverse reaction rate and shorter induction, anesthesia recovery, and PACU discharge times. Additionally, the intra- and postoperative Ramsay Sedation Scale scores were statistically higher in the research group than in the control group. Remimazolam besylate was significantly more effective than DEX in gastrointestinal surgery in obese patients and had a higher safety profile and value in clinical promotion.

Understanding and Controlling Electrostatic Discharge in Triboelectric Nanogenerators.

Triboelectric nanogenerators (TENGs) have been widely used to harness various forms of mechanical energy for conversion to electrical energy. However, the contentious challenge in characterising TENGs is the lack of standard protocols for assessing mechanical-to-electrical energy conversion processes. Herein, macroscopic signal analysis is used to identify three key charging events within triboelectric signals: charge induction (CI), contact electrification (CE), and electrostatic discharge (ESD). By considering two phases of motion during contact-separation (approach and departure of the contact materials), CI arising from the motion of bound surface charge (varying electric field) between opposing contact materials is shown to dominate the measured displacement current signal, rather than the process of CE itself. Furthermore, the conventional signal (i. e., voltage, current, charge) interpretation of CE and CI during approach and departure phases is re-assessed, to indicate that the sudden spike of current often observed immediately prior to contact (or after separation) arises from polarity inverting electrostatic discharge (ESD). This aspect of the measured triboelectric effect, which is often ignored, is crucial for the design of TENGs and hence, techniques to enhance the understanding and control over the stochastic occurrence of ESDs is explored. The methods proposed for the deconvolution of the macroscopic signal components of TENGs, and mitigation of ESD occurrences, will allow for precise quantification of the associated charging events. The applications of this study will template the design and development of future super-TENGs with optimised energy conversion capabilities.

End-to-end Mathematical Model of a Radio-Frequency Inductive Jet Discharge of Lowered Pressure

End-to-end Mathematical Model of a Radio-Frequency Inductive Jet Discharge of Lowered Pressure

A method of risk assessment for static ignitions

This paper presents a method of risk assessment for static ignitions that can be widely used overseas. It describes how the developed risk assessment method identifies static ignition hazards and analyses static ignition risks. This method has been developed on the basis of the flow of procedures in IEC/ISO Guide 51, lessons learned from incidents over 50 years and the survey of the situation of electrostatic risk assessment in Japanese industry, and has been maintained as an implementation guide to assist safety managers since 2008. The method includes a process/operation review; hazard identification for explosive atmosphere formation, charging, electrostatic induction and electrostatic discharges; static ignition risk estimation and evaluation; and risk reduction countermeasures. Tools are also provided to aid implementation: a risk assessment sheet to follow the method and record the results, and 30 check items to identify static ignition hazards. The method with the guide has been adopted by many safety managers in Japan.

Etching of a fluoropolymer coating synthesized by the hot wire chemical vapor deposition method in a low-frequency induction discharge plasma

The process of plasma etching for the formation of a biphilic pattern in a continuous homogeneous fluoropolymer coating on a copper substrate is studied. Argon or oxygen plasma of low frequency ferromagnetic amplified induction discharge is used to etch a fluoropolymer coating. Plasma etching was carried out through a mask with parallel slits. The etching rate in argon plasma was 10 nm/min, the etching rate in oxygen plasma was 60 nm/min. Biphilic surfaces were obtained, consisting of fluoropolymer strips on a copper surface. It has been shown that when using both argon plasma and oxygen plasma, it is possible to create biphilic surfaces by etching a continuous homogeneous fluoropolymer coating through a mask. Moreover, oxygen plasma is better suited for this because it has a higher etching rate and weakly changes the wettability of the surface.

Frequency Dependence of Parameters of an Inductive RF Discharge Placed in a Weak Magnetic Field

Frequency Dependence of Parameters of an Inductive RF Discharge Placed in a Weak Magnetic Field

Promising methods for improving the radio-frequency ion thruster performance

Improving the reliability and efficiency of available electric propulsion schemes is one of the priority areas of space technology development. In particular, this should be done for ensuring the guaranteed removal of spacecraft to a disposal orbit at the end of their active life, which, in turn, will slow down the growth in the number of space debris objects in the most exploited regions of near-Earth space. The paper considers ways to improve the power and mass efficiency of one of the modern electric propulsion types - a radio-frequency ion thruster with an inductive radio-frequency discharge. Using an engineering physico-mathematical model, computational studies were performed to optimize the shape of the radio-frequency ion thruster main components, namely the discharge chamber and the grids of ion-extraction system. The thrust of the thruster was used as the optimization criterion; it was determined from the calculated ion density distributions in the radio-frequency discharge plasma. Such an approach to refine the performance improvement methods has not previously been applied to radio-frequency ion thruster. The ion density distributions, as well as the thruster integral characteristics determined from them, such as the thrust, total ion current from the thruster, propellant utilization factor, ionization cost and a number of others, were calculated for two actual standard sizes of radio-frequency ion thruster with the beam diameters of 80 mm and 160 mm, which can be used to solve the problems listed above. Besides, for the defined optimal configurations of thruster with two standard sizes the calculations were made to assess the possibility for increasing the thruster integral characteristics by applying an additional magnetostatic field in the radio-frequency discharge region. The study revealed the possibility of noticeable performance improvement compared to the basic radio-frequency ion thruster design with hemispherical discharge chamber and flat grids of the ion-extraction system.

Development and Testing of a High-Frequency Driver for a Charge-Exchange Source of Negative Hydrogen Ions

A source of negative hydrogen ions based on the recharging of a beam of positive ions in a gas target is being developed at the Institute of Nuclear Physics. G.I. Budker SB RAS. The charge exchange source can be used to inject into the tandem accelerator a neutron source intended for boron neutron capture therapy. One of the important elements of the source is the plasma emitter, which creates positive ions for primary acceleration. As an emitter, a high-frequency driver based on an induction discharge and designed for a multi-second operating mode was chosen. In this work, we measured the emission characteristics of a high-frequency driver using a moving grid probe. As a result, the parameters necessary for the use of the driver in a rechargeable source of negative ions have been achieved. The analysis of experimentally measured thermal loads in the multisecond mode is carried out.

Numerical model of a gaseous inductive discharge in oxygen, taking into account the complete scheme of the vibrational kinetics of O2 molecules

In this work, the two-dimensional model of inductively coupled plasma discharge in oxygen was developed. The model includes hydrodynamic equations in drift-diffusion approximation for describing the kinetics of charged (electrons and ions) and neutral plasma particles, Maxwell’s equations for electromagnetic fields, and equations for the temperature and neutral gas flow as well as a detailed scheme of plasma-chemical reactions. The model was tested against theoretical and experimental data in a simple cylindrical chamber. The electron density and temperature distributions were obtained over a wide range of powers deposited in the plasma (100–500 W) and compared with literature data. Also, the complete scheme of the vibrational kinetics of O2 molecules was included in the model. The vibrational distribution function was calculated in low-pressure inductive discharge as well as spatial distributions of plasma parameters (density and temperature of electrons, excited components, neutral gas temperature, etc.) and flows of charged and active neutral particles at the reactor walls.