Arc Motion Research Articles

The investigation of arc fluctuations in thermal plasma torch using 3D modeling approach

Two and three-dimensional transient models of a thermal plasma torch are presented to analyse the effect of operating conditions on arc root fluctuations for various types of anode configuations. The computational fluid dynamics code, OpenFOAM(c), is utilised in a modified form to model the arc and plasma flow inside the argon plasma torch. Modeling a thermal plasma requires a combination of mutually related fluid dynamics and electromagnetic phenomena which dictate the size and stability of the arc column. While the 2D axisymmetric model is effective in depicting the average energy and average velocity profiles of plasma gas, it fails to describe the fluctuations in arc behaviour and its mode of attachment on the anode. In a 3D model, the arc movement is captured in both axial and azimuthal directions wherein the arc-root attachment on anode surface seems to fluctuates in a periodic manner and the voltage fluctuations mirrors the arc-root attachment behaviour within the system. We have here investigated the effect of operating conditions on the frequency of this arc reattachment, finding that the input current and gas flow rate have a significant effect on arc behaviour. We have also reported the effect of arc voltage perturbations on the exit plume properties (velocity and average temperature) and finally the effect of anode nozzle geometry on the fluctuations and plume behavior is presented.

Properties of Vacuum Arcs Generated by Switching RMF Contacts at Different Ignition Positions

The influence of initiation behavior of the drawn arc on the arc motion, on arc characteristics during the active phase, as well as on the post-arc parameters, was studied. The study was focused on arc dynamics, determination of the anode surface temperature after current interruption, and diagnostics of metal vapor density after current zero crossing. Different optical diagnostics, namely high-speed camera video enhanced by narrow-band optical filters, near infrared spectroscopy, and optical absorption spectroscopy was applied. The initiation behavior of the drawn arc had a clear influence on arc parameters. Higher local electrode temperature occurs in case of the electrodes with ignition point near the outer electrode boundary. This further causes an enhanced density of chromium vapor, even in cases with lower arc duration. The results of this study are important for design development of switching RMF contacts for future green energy applications.

Multifield Coupled Dynamics of Power Supply Arc Based on Image 3D Reconstruction Mathematical Model

During the conversion process of the short-circuit arc to the submerged power supply arc, because the short-circuit arc diameter is much larger than the submerged power supply arc, the specific position of the submerged power supply arc cannot be determined, and the initial position of the submerged power supply arc has a certain randomness. The purpose of this paper is to try to use the binocular stereo vision method to reconstruct the submerged arc image in three dimensions, obtain the moving image of the arc, obtain more comprehensive information than the two-dimensional image, and multi-field coupling dynamics of the power supply arc. In this paper, the multi-field coupling effects of electromagnetic force, thermal buoyancy, wind load and air resistance of the submerged arc of the half-wavelength transmission line are considered comprehensively, and the chain arc model is incorporated into the force equation and motion model of the submerged arc. By deeply analyzing the formation and motion mechanism of the arc root, the arc root model of the submerged power arc is established, and the optimal selection method of the current element length is proposed. The physical simulation experiment of the half-wavelength submerged arc is carried out, and the simulation results are compared with the experimental results to verify the effectiveness of the simulation model. By comparing the trajectory and self-extinguishing time of different submerged currents, wind speeds and winds to the submerged power supply arc, the effects of wind load, thermal buoyancy and electromagnetic force on the arc are analyzed, which indicates that the built arc model can effectively account for the wind load. The influence of submarine power arc motion and self-extinguishing characteristics. The results show that the submarine power arc image is acquired by constructing a binocular stereo vision system, and the obtained submersible arc image is reconstructed three-dimensionally. The three-dimensional image of the arc is obtained and compared with the actual image. The result shows that the three-dimensional reconstruction The result is effective, and the exploration study provides a new method for further obtaining the multiple variations of the true arc length of the arc with the arcing time.

Effect of TMF and AMF Components on Expansion Process in Different Ignition Modes of Vacuum Arc Between Spiral-Type TMF Contacts

The drawn vacuum arc begins with a bridge column formed from the explosion of a liquid metal bridge after separating the contacts. The expansion process of the initial arc has an effect on arc motion or diffusion. In order to deeply study the influence of transverse magnetic field (TMF) and axial magnetic field (AMF) on the drawn arc characteristics in the initial expansion stage, in this article, arc ignition mode and appearance under two groups of contacts with different AMF and TMF components were experimentally studied. It was found that simultaneously reducing TMF and AMF components would end the expansion stage earlier, and the fluctuation of the arc column pressure during the expansion was larger. When TMF and AMF components were further reduced, the arc needs to take a longer time to extend across the slot gap due to insufficient Ampere force. When TMF was basically unchanged and AMF was reduced, the arc burned more intense, the diameter of the arc column was smaller, and the arc would merge earlier in multipoint ignition mode. The characteristics of arc voltage, pressure, and duration of expansion stage were analyzed, founding that the arc with a moderate TMF and AMF components had a smaller rising slope of arc voltage, a faster reducing speed of arc pressure, and a smaller range of the duration of expansion stage. In addition, the variation of magnetic field strength in different ignition modes and contact structures during the arc expansion stage was simulated to explain the mechanism of arc behavior.

Outcome of primary tendon grafts for open Zone 3 extensor tendon injuries

Open injuries of the extensor mechanism in Zone 3 (dorsum of the proximal interphalangeal joint) have poor outcomes. We retrospectively analysed the outcomes of treating 19 Zone 3 extensor tendon injuries in 17 patients. The treatment comprised wound excision and debridement, primary tendon graft to reconstruct the damaged/missing extensor tendon, skeletal fixation when required, local flaps to vascularize the zone of injury and immediate short arc motion therapy. Using the criteria defined by Geldmacher etal., the outcome was predicted to be poor in nine, satisfactory in seven and good in three cases. In this study the outcomes were excellent in 10, good in six and satisfactory in three cases. Mean range of motion was 75° (range 25°-115°) at the proximal interphalangeal joint. We conclude that using the protocol described there should no longer be the perception of a dismal outcome for these complex Zone 3 extensor tendon injuries.Level of evidence: IV.

Experimental Study of Relationship Between Arc Light Intensity and Temperature in Low-Voltage Switching Devices

Arc motion in a quenching chamber has a significant influence on switching performance in a low-voltage switching device (LVSD). A high-speed optical arc imaging system (AIS) has been used to investigate the influence of the design parameters of a quenching chamber on arc motion. Arc light intensity is transmitted to the photodiodes of the AIS through optical fibers during the switching process. The AIS and associated software enable the detailed arc motion to be tracked inside the chamber at an image sampling rate of 1 MHz. Since higher arc temperature leads to greater radiation, it is assumed that the arc light intensity measured by the AIS is related to the arc temperature. However, there has been a little empirical study of the correlation between the arc temperature and light intensity measured by the AIS. In this article, the relationship between the arc temperature and light intensity is investigated by measuring arc spectra and arc images. Arc spectra are captured by a spectrometer when the arc is ignited by copper wire in a narrow enclosed chamber, and they are used to calculate the arc temperature by the Boltzmann plot method. At the same time, the AIS records the arc images from points adjacent to the fiber of the arc spectrometer. It is found that the arc light intensity measured by the AIS is directly related to the arc temperature; the correlation between the fourth power of temperature and the light intensity is an approximately linear trend.

Gas dynamics of the pulsed electric arc in the transversal magnetic field

The arc discharge in magnetic field is one of the promising methods to intensify the kinematic transport in various systems. In this work, a detailed study of the flow arising in ambient air during the movement of a pulsed arc in external magnetic field was done. The study was performed using PIV and shadow flow visualization in parallel with the numerical modeling in a 2D MHD approach. The flow evolution during the electric current pulse was analyzed based on the vorticity generation equation. The flow relaxation after the current termination is considered, indicating a significant reduction of the gas velocity after the current termination due to rarefaction waves propagation. The typical flow structure remaining after the MHD interaction is a toroidal vortex with velocity magnitude up to 0.4 of the maximum arc movement velocity during the pulse.

The research of the electric arc movement of direct current arc gas heater

This article deals with experimental definition of the electric arc moving speed and develops relation of current strength change at interelectrode gap 2, 3 and 4 mm considering different consumption of orifice gas. Shadow photographs of the electric arc and traces on the electrodes have been also provided.

Experimental Studies of Arc Motion Between Two Parallel Runners with Splitter Plates

In this paper, we present an experimental study in a simplified arc chamber geometry of Low-Voltage Circuit Breaker (LVCB). The influence of vent aperture on arc motion and the influence of splitter plates on arc voltage drop and arc motion are studied. The arc chamber is composed by two parallel arc runners and following the configuration chosen by one or two splitter plates. The experimental setup is completed by a generator (capacitor bench with triggered switch), a high-speed camera and electrical measurements. The arc ignition, arc displacement, arc splitting and arc re-strike have been observed. The results will be described and discussed for different experimental configurations.

Arc characteristics in short electrical arc high-efficiency milling for GH4169

To solve core problems of slow arc response and unstable combustion, arc movement characteristics and arc action rules in short electrical arc milling are studied using a high-speed acquisition system and the Phantom high-speed camera in this article. To improve arc reignition, the characteristic parameters of arc discharge are determined as a discharge gap of 0.053 mm and discharge time of 2180 μs. A short electrical arc milling experiment with nickel-based superalloy GH4169 is carried out, confirming that the continuous stable discharge of the arc can easily produce a material removal rate of 40 g/min and a tool wear ratio of 0.8%. An SU8010 scanning electron microscope and energy spectrum analyzer are then used to study the erosion mechanism of GH4169 in short electrical arc milling. This article aims to expand the processing range of short electrical arc machining in the field of special material processing to provide experimental and theoretical bases for the development of short electrical arc milling technology theory and methods.

Plasma hardening of elements for soil cultivating instruments

ABSTRACT The properties of 65 G steel used in the manufacture of elements of soil-cultivating machines, strengthened by plasma quenching through the use of the UDGZ-200 serial installation, without water cooling, are studied. It is established that quenching leaves on the surface bands of the heat tints. Surface roughness varies from Ra 0.3 to Ra 2.6 as a result of hardening. When quenching a plate 30 mm thick, the cooling rates in the region of pearlite decomposition of austenite (750 … 500 °C) are in the range of 50–100 °C/s, which allows the supercooled austenite to be maintained until the martensitic transformation begins (270°C). In this case, quenching condition is provided. At temperatures below the martensitic transformation, the cooling rates slow down, which a factor is contributing to the prevention of cracking during quenching. As a result of reducing the arc movement speed from 33 to 24 and up to 14 m/h, occurs an increase in the hardening depth with the boundary of HV500 450 from 0.25 up to 0,35 and 0,50 mm and an increase in the width of the hardened strip from 9 to 11 and to 13 mm, respectively. Reducing the thickness of the plate from 30 to 10 mm is accompanied by an increase in the depth of hardening to 1.9 mm. The wear resistance of normalized 65 G steel as a result of plasma quenching by steel indenter friction (ShX-15) is increased by 4 times. When rubbing with corundum indenter, the wear resistance of the hardened steel is 15.3 times higher than in the case of friction with a steel indenter. This makes plasma hardening promising for strengthening elements of soil-cultivating machines in which wear conditions are closer to tests by a corundumindenter.

Effect of Magnetic Arc Oscillation on the geometry of single-pass multi-layer walls and the process stability in wire and arc additive manufacturing

Abstract Magnetic Arc Oscillation was applied during the construction of single-pass multi-layer walls of low carbon steel and Ti6Al4V by the Gas Tungsten Arc Welding-based Wire and Arc Additive Manufacturing process, and the influence on the geometry and the process stability was evaluated. The geometric features were assessed using transverse section macrographs and the effects of different patterns and frequencies of oscillation on the arc characteristics, metal transfer and weld pool behavior during the layer deposition were investigated using high speed and welding cameras. The results show that this technique is efficient for making thinner walls by minimizing the overflow of the weld pool and, in some conditions, increasing deposition efficiency. Furthermore, the distribution of material along the wall length becomes more homogeneous. An explanation of the effects of Magnetic Arc Oscillation on the wall geometry based on forces that act on the molten metal during layer deposition was made. Because of the swinging movement of the welding arc, the heat is distributed over a larger area, and the power density decreases. Thus, fewer previous layers are remelted, and the volume and the weight of the weld pool reduce. The weld pool temperature drops, and the surface tension force and the viscous friction increase. The distribution of arc pressure also becomes less concentrated, and the arc force on the molten metal decreases. Additionally, a magnetic force appears on the molten metal, which contributes to a change in the direction of the resultant force on the weld pool.

The decoupling behavior of arc coupling and rotating in seven-wire rotating arc EGW

In the present study, the decoupling behavior of the arc coupling and rotating in the seven-wire rotating arc electrogas welding (EGW) is studied. It is found that the arc motion processes is composed of the arc axial motion process, arc coupled motion process, and arc circumferential rotation process. The arc is moving up and down along the axial direction. Moreover, it is observed that as the welding current increases, the arc axial motion frequency accelerates while the corresponding motion amplitude decreases. The arc coupled motion process does not always exist, and the arc coupled motion time and arc coupled forces increase as the welding current increases. Obtained results show that the arc axial motion hinders the arc coupled motion and the arc circumferential rotation. Meanwhile, the arc coupled motion and circumferential rotation are more obvious as the welding current increases.

Visualizing Arc mRNA transfer using single molecule fluorescence assays

The transfer of genetic material between cells has been implicated in both maintaining neuronal function as well as the proliferation of many diseases and disorders, especially neurodegenerative disorders. Regulation of mRNA transfer through transport and localization is conducted by RNA binding proteins (RBPs), making RBPs responsible for control of gene expression. The activity‐regulated cytoskeleton‐associated protein, Arc, is an important component of maintaining neuronal synaptic plasticity which ensures the proper flow of cognitive information. In Alzheimer’s disease, an increase of Arc protein expression and localization in synaptic activity areas has been observed in compensating for memory and cognition loss. Although Arc is thought to be released from the synaptic cleft through Arc‐formed capsids to transfer Arc mRNA into new target cells, the mechanism of action is unknown. This project uses single molecule fluorescence methods to interrogate the dynamics of Arc allowing for visualization of the potential movement of Arc capsids/Arc mRNA and the transfer of this genetic information in human cells. Preliminary studies of the Arc using single molecule fluorescence in situ hybridization (smFISH) and live cell imaging techniques has shown a static trajectory of Arc diffusion. Further studies of the transport and transfer of mRNA from Arc capsids will allow for an understanding how this machinery works that can be the basis for the development of new drug delivery methods for diseases with RNA targets.Support or Funding InformationNIH grant number: 1T32GM1320461

Study on the Influence of Different Magnetic Fields on Vacuum Arc Based on COMSOL

In this paper, the finite element software COMSOL is used to establish a two-dimensional simplified vacuum arc model, and the parameters are set in COMSOL to set the conditions. A transverse magnetic field is applied between the two contacts, and the transverse magnetic field can cause the arc to burn in one direction, reducing the ablation of the contacts by the arc. In this paper, the process of arc motion under different magnetic field strengths is studied. The trajectory of arc motion can be seen, reflecting the movement state of the arc at different moments and the comparison of the maximum contact temperature.

Model of the Retrograde Motion of a Vacuum Arc: Comparison to Experiments

In the absence of an external magnetic field, a cathode spot (CS) of a vacuum arc experiences a Brownian random walk (jumps) along the surface. A magnetic field parallel to the surface causes spot drift in the anti-Amperian direction (retrograde motion). Three statements are suggested to explain the retrograde motion and its features: 1) each CS jump is associated with a voltage drop fluctuation $\Delta {V}$ ; 2) the tangential electric field (the Hall field) is created by the additional positive surface charges at the retrograde side of the spot. This field results in an additional voltage drop at the retrograde side of the spot $\delta {V}$ ; and 3) the probability of the spot jumping in the retrograde direction is proportional to $\delta {V} /\Delta {V}$ . Calculations based on these statements allow one to achieve qualitative and, in many cases, quantitative agreement with experiments concerning retrograde velocity dependences on these external parameters: magnetic field, arc current, interelectrode gap, and cathode surface conditions. No adjustable parameters were used in these calculations.

Study of high-speed GMAW assisted by compound external magnetic field

A magnetic generating device was proposed to regulate the transverse and backward flow of weld pool for high-speed gas metal arc welding (GMAW). Compound external magnetic field (EMF) was simulated to verify the feasibility of designed magnetic generating device. The highest welding speed with good weld bead appearance was 1.7 m/min with the wire feed speed of 9.0 m/min when compound EMF was applied. The effect of the compound EMF on the arc and droplet motion was studied by image acquisition system. The suppression mechanism of the compound EMF on the undercut defect of high-speed GMAW was analyzed. The mechanism of the influence of the applied compound EMF on different welding speeds and welding currents was studied by the application of the compound EMF-assisted welding process, and low-cost, high-quality, and high-speed welding technology was realized.

Impact of cathode loss on plasma characteristics, microstructures and properties of 7YSZ coatings in PS-PVD

The slight changes in geometry and mass of the cathode of O3CP plasma torch during service life caused the variety of arc motion between the cathode and anode. The voltage appeared to rise first and then fall. In this experiment, the impact of cathode loss on plasma characteristics, microstructures and properties of 7YSZ coatings was investigated. Optical emission spectroscopy (OES) was used to characterize the plasma jet characteristics such as plasma temperature and electron number density. It is found that vapor deposition is the main deposition mechanism, and the microstructures of the coatings are mainly affected by the supersaturation and subcooling of the vapor phase, which determine the nucleation and growth of crystals. At the middle of cathode service life, the plasma temperature and electron number density are the highest and the powder is completely evaporated. High crystal growth rates and surface diffusion lead to large columnar crystals with large grain size. The best thermal shock resistance. The thermal shock resistance is the best in this case. When the cathode is in the beginning and end of service life, there are columnar grains with small size produced and many solid particles in the gaps due to diffusion difficulties generated by low temperature. Shadowing enhances to manufacture fine grains and few branches. The presence of solid particles prevents the release of thermal stress and reduces thermal shock resistance of coatings. Fine grains prevent cracks propagation to improve the bonding strength of coatings.

Investigation on arc behavior of AgNi electrical contact material with three-dimensional network structure

To clarify the arc characteristics of Ag–Ni contact material, the Ag-8wt.%Ni contact material with three-dimensional network structure was prepared by powder metallurgy, and the microstructure was characterized by scanning electron microscopy and transmission electron microscopy. The electrical contact tests were performed for different operations, the arc motion behavior, arc-preferred characteristics and surface morphology evolution were investigated, and arc erosion mechanism was discussed. The results show that serious arc erosion prefers to occur on the Ni-rich phase at the eroded anode surface. However, at the cathode region of the arc-eroded surface, the reticulate Ni phase restrains the expansion of molten pool and decreases arc erosion at the early stage of electrical contact tests. The difference in the arc-erosion behaviors of anode and cathode can be attributed to the changes in the mean free path of free electrons and cations in the contacting bodies. With the increased use of electrical contacts, the floatation, dissolution and subsequent precipitation of Ni cause the formation of fine Ag-rich and Ni-rich phase, which not only disperses the thermal energy and reduces the splash, but also decreases the fluctuations of arc duration and arc energy. In addition, the break-arc-energy presents larger fluctuation than make-arc-energy.

The Formin Inhibitor, SMIFH2, Inhibits Members of the Myosin Superfamily

The formin inhibitor, SMIFH2, is widely used in cell biological studies. It inhibits formin-driven actin polymerization in vitro with half maximal inhibition (IC50) values ranging from 5 to 15 µM for different formins. In search of formin function in F-actin retrograde flow, we examined the effect of SMIFH2 on the centripetal movement of actomyosin transverse arcs in detergent-permeabilized cells induced by ATP addition. In this system, neither polymerization nor depolymerization of actin can occur, because of the absence of G-actin and the presence of F-actin stabilizer, phalloidin.