Arc Motion Research Articles

Investigation of the influence of opening speed on vacuum arc under transverse magnetic field

The objective of this paper is to investigate the vacuum arc characteristics on transverse magnetic field (TMF) contacts at different opening speeds. Experiments are carried out at different opening speeds. The experimental current ranges from 7 to 16 kA (peak current) at approximately 50 Hz. The contact material is CuCr30. The results show that increasing the opening speed increases the expansion speed of the arc after ignition. A higher opening speed increases the gap distance at which an anode spot occurs and reduces the duration of the instability stage, and it also reduces the duration of the motion stage. The arc motion can be optimized by adjusting the opening speed. The moment of contacts separation has no obvious influence on the gap distance at the transition of the arc mode. When the arc ignites between the arms, it expands slowly. This phenomenon is analyzed by a finite element method. The simulation results show that the ignition position influences the current direction, which influences electromagnetic force of the arc. The radial electromagnetic force is smaller when the arc ignites between the arms, causing a stagnation of the arc.

Modeling and simulation study on the ablation characteristics of DC contactor contact

The DC contactor can frequently break the high current control circuit, and the arc motion characteristic in the current breaking process is closely related to its electrical life and reliability. In this paper, a three-dimensional magnetohydrodynamic arc model of the DC contactor considering contact motion and external circuit characteristics is established. On this basis, the influence of the vapor produced by the contact ablation on the arc behavior is studied, and the ablation rate of the cathode in a single breaking process is calculated. The results show that the arc temperature is reduced, the motion speed is slowed down, and the arc burning time is shortened due to the presence of copper vapor produced by ablation. The ablation rate of the cathode during a single arc is 8.9 µg/C.

Simulation study on arc motion process of DC miniature circuit breakers

Based on the theory of magnetohydrodynamics, a mathematical model of air arc in the arc extinguishing chamber of a DC miniature circuit breaker was established. By coupling external circuit characteristics and contact movement process, the motion process of the arc was simulated and analyzed. On this basis, the effects of breaking speed, time constant, and magnetic field on the arc motion characteristics were studied. The study showed that increasing the breaking speed appropriately and adding appropriate magnetic field can improve the breaking performance of DC miniature circuit breakers. The research results can provide reference for the optimization design of DC miniature circuit breakers.

Peri‐Siberian Ordovician to Devonian Tectonic Switching in the Olkhon Terrane (Southern Siberia): Structural and Geochronological Constraints

AbstractThe Olkhon Terrane is thought to preserve a record of the initial collision of the Siberian Craton with its peripheral orogenic system during the early Paleozoic. However, the related tectono‐metamorphic process and its time‐scale remain obscure. To address this issue, new structural observations combined with U‐Pb zircon and monazite and 40Ar/39Ar biotite geochronology were conducted in the migmatitic‐granitic Anga‐Sakhurta Zone of the terrane. An earliest syn‐collisional event associated with the development of a c. 500–480 Ma sub‐horizontal migmatitic fabric is confirmed. This early fabric was affected by later extensional doming in association with emplacement of partial melts (in terms of c. 470–445 Ma granite sills) parallel to the sub‐horizontal mechanical anisotropy. Subsequent upright folding leading to amplification of extensional domal structures and heterogeneous vertical transposition of composite horizontal fabric occurred soon after the doming, as indicated by intrusions of residual melts into the axial planes of the upright folds. The latest episode of deformation was marked by development of greenschist‐facies sinistral shear zones surrounding the Anga‐Sakhurta Zone at c. 420–400 Ma. An updated tectonic model involving (a) Middle–Late Ordovician crustal thinning associated with horizontal crustal flow, (b) Silurian crustal shortening related to northwards movement of Cambrian magmatic arc of the Birkhin Complex to the south, and (c) Early Devonian lateral extrusion and sinistral shearing associated with progression of the Birkhin Complex promontory, is proposed. Results from this study shed lights on the collisional evolution of peri‐Siberian orogenic system during the early stage evolution of the Central Asian Orogenic Belt.

Electric field-influencing combustion behaviors of droplets of ethanol, biodiesel and diesel

The droplet combustion in an electric field is fundamental for the electrospray combustion. In this paper, experimental research was done to investigate the effect of the vertical electric field on the combustion behaviors (including the flame and droplet characteristics) of droplets of ethanol, biodiesel and diesel. The outcomes demonstrated that the flame morphology was controlled by the competition between the electric field force and natural buoyancy. As the electric field strength (E) increased, the upward flame (0 ≤ E < 100 kV/m), quasi-spherical flame (E ≈ 100 kV/m) and downward flame (100 < E ≤ 200 kV/m) successively emerged. This expressed as a decrease in upper flame heights and an increase in bottom flame heights. The fuel order of the flame height variation extent was ethanol < biodiesel < diesel. An increase before 100 kV/m and a decrease after 100 kV/m for the flame width existed, whose value variations were similar in all droplets. These differences in flame size had a direct impact on the magnitude of flame fronts, which in turn determined the area where the fuel vapor and oxygen reacted. Therefore, the combustion duration of the biodiesel and diesel droplets increased before 100 kV/m and decreased after 100 kV/m. Due to the downward movement of the electric arc, the combustion duration of the ethanol droplet increased with the electric field strength. The maximum increases in combustion durations of the ethanol, biodiesel and diesel droplets in the electric field could achieve 14.1%, 18.1% and 21.9%, respectively. This work supplies a further understanding of the droplet combustion in electric fields and the electrospray combustion.

Experimental study on physical characteristics of dielectric-boosted gliding arc discharge

To augment the plasma processing capability, and obtain an enhanced plasma area, a dielectric-boosted gliding arc discharge (DBGAD) reactor was developed. The electrical, gliding arc motion and energy injection characteristics of the DBGAD reactor were investigated. The process of AC DBGAD includes breakdown gliding mode (B-G) and steady arc gliding mode (A-G), with peak currents on the order of amperes in B-G mode and on the order of milliamps in A-G mode. Situating a 50 mm quartz dielectric underneath the plasma area at a distance of 10 mm from the base of the blade electrodes, enhanced discharge power is obtained, and sustained arc gliding time is extended efficiently. At an input voltage of 9.2 kV, the DBGAD demonstrates a 27% increase in arc stabilization gliding time compared to the gliding arc discharge (GAD) and delivers an average discharge power 1.12 times superior to that of the GAD. In the DBGAD reactor, the plasma column twists following the minor vortex of the reflow and has a more pleated shape. The energy injection characteristics are analyzed using the fast Fourier transform system, and the results show that the current harmonic content of DBGAD is reduced and the discharge fluctuation is mitigated, which is favorable for stable discharge. The primary benefit of incorporating quartz dielectric is that it provides the mobile arc with a supportive force, leading to a more substantial and intensely focused plasma field. This in turn facilitates greater system stability and yields measurable enhancements in power output.

Late Cretaceous‐Recent Tectonostratigraphic Evolution of the Yucatan Back‐Arc Basin, Northern Caribbean Sea

AbstractThe 110,000 km2 Yucatan Basin in the northern Caribbean Sea is critical for understanding the Late Cretaceous to Recent tectonic evolution of the Caribbean‐North American plate boundary. This study integrates gravity, magnetic, and a 5,500 km grid of 2D seismic data to carry out a tectonostratigraphic analysis of the Yucatan Basin. These data provide the first recognition of 38–102 km‐long spreading ridges that constrain a SW‐NE opening direction in the western Yucatan Basin. The age of this oceanic crust is constrained to be late Paleocene‐middle Eocene (57–42 Ma) based on heat flow measurements, depth‐to‐seafloor, and three sedimentary sequences inferred to be Eocene—Recent in age based on stratigraphic correlations to distant wells. We interpret the Yucatan Basin as a back‐arc basin formed during the northeastward movement of the Caribbean volcanic arc that is now exposed in Cuba, evolved during the early Cretaceous to middle Eocene, and was terminated by collision with the Bahama carbonate platform during the late Paleocene to middle Eocene. We identify regional, left‐lateral strike‐slip faults that extend into the Cuban volcanic arc, as observed in other active back‐arc basins. We propose that the Yucatan back‐arc basin once formed the northwestern extension of age‐equivalent back‐arc basins in Hispaniola, where the basin is inverted, topographically elevated, and strongly shortened, and in the Lesser Antilles where the Paleogene back‐arc basin has remained undeformed and submarine. This once‐continuous back‐arc basin was disrupted and left‐laterally offset by ∼500 km during the Late Eocene‐Recent formation of the Cayman trough strike‐slip system.

Research on driving force and dynamic characteristics of pantograph–catenary arc

Pantograph–catenary (PC) system is the key current collection equipment for electrified rail vehicles. The PC arc ages the contact line and pantograph abnormally, which is a limiting factor for rail transit to increase the speed of operation. To reduce the harm caused by the PC arc, in this article, a new PC arc chain model was established, which considered the arc current element mass and the acceleration process, updating the control equations. Meanwhile, a PC arc experimental platform was built in order to verify this model. It is demonstrated that the simulation results obtained by this work fit the arc and are suitable to describe the arc in the field. Experiments have found that the evolution of PC arc can be divided into three distinct processes: arc initial process, rapid stretching process and violent oscillation process. Combined with the model, the driving force and dynamic characteristics of the PC arc root and column in each process have been studied. The electromagnetic force dominates the arc evolution in the first two processes, and then the wind load dominates the last process. Besides, thermal buoyancy dominates the arc root jumping behavior. The driving mechanism for the movement of arc has been revealed. The arc root first suppresses the arc column, and then the arc column pulls the arc root. It is helpful for controlling PC arcs in the field.

Arc-to-sheet printer for high-precision patterning with positional errors below 6 ppm at 3σ level: Trochoidal trajectory mechanism for rotary motion of arc

Pattern registration accuracy is a key property in printing processes, especially for miniaturized printed electronic devices that require the overlay of multiple layers. Except for inkjet and screen printing, various printing methods such as gravure offset, flexographic, and reverse offset printing typically use a roll-to-sheet type printer; however, registration has been limited, especially in the machine direction because of the speed variation in rotary motion of a cylindrical roll. We developed an arc-to-sheet type printer in which the rotary motion of an arc was realized by a trochoidal trajectory because such a mechanism can only be constructed using the translational motions of high-precision linear actuators. A prediction model for the behavior of the contact point of the arc during printing was also developed, along with a method for compensating for mechanical and assembly errors, which was verified by laser displacement measurements and torque exerted on the linear motor of table. Cu patterns reverse offset printed by the developed arc-to-sheet printer had positional errors of less than 3σ < 6 ppm with an optimized processing condition, achieving an unprecedented level of accuracy in printed electronics.

Effect of a longitudinal magnetic field on arc motion and joint structure of a hollow stud

Given the non-uniform melting of the end face of a joint and the local non-fusion of the joint in large-diameter hollow stud welding, to research the law of arc motion, the joint-forming quality, weld microstructure and mechanical properties in the process of hollow stud welding propelled by a longitudinal magnetic field were investigated in this study. The results reveal that under the influence of a longitudinal magnetic field, the arc on the end of a stud is affected by the Lorentz force and spirals downward. In the welding process, with an increase in magnetic field intensity, the arc uniformly burns the stud end face, preventing local non-fusion and resulting in a well-shaped joint. Under the action of magnetic field stirring, eutectoid ferrite is broken, the content of eutectoid ferrite and bainite is diminished, the nucleation barrier is reduced and the grain is refined. Under the action of a longitudinal magnetic field, the shear strength of the hollow stud welded joint rises to 312 MPa, surpassing the strength of a joint welded without a magnetic field.

Study on microspot splitting characteristics in cathode spot motion of vacuum arc

The control of cathode arc spot and the removal of macroparticles have always been key problems in the preparation of coatings of vacuum arc ion plating. This work aims to explore the internal structure and the formation mechanism of cathode arc spot as well as the effects of different parameters on its characteristics. Moreover, the work attempts to find a way to improve the arc spot discharge fundamentally from the inside of the spot by photographing the cathode arc spot dynamically with a high-velocity digital camera. The results show that there are the microscopic phenomena of microspot splitting, microspot accompanying motion and periodic motion in the interior of the cathode arc spot. The continuous self-splitting characteristic of microspot is unstable under the intermittent microexplosive emission mechanism, resulting in periodic splitting and merging. Although the stability of microspot splitting can be relatively improved by adjusting the deposition parameters, the nature of the phenomenon that relatively concentrated discharge occurs periodically under the DC arc cannot be changed. In this work, the idea of promoting arc spot splitting is further analyzed and proposed in the mechanism level, and the feasibility of reducing and refining MPs defects by arc spot splitting is also discussed.

Numerical simulation and analysis of contact erosion by high-current and low-voltage air arc considering the movement of arc

When a low-voltage circuit breaker (LVCB) breaks a high current, the contact erosion caused by the arc greatly reduces the LVCB’s breaking performance and service lifetime. Therefore, this paper uses AgW alloy contacts as a research object, which are commonly used for breaking high currents, and establishes a contact erosion model for an LVCB with a breaking current of 14 kA. The model considers the energy balance of a contact surface and uses a solidification and melting model and a dynamic mesh model to deal with the phase transition problem of the contact material and introduces the arc movement into this model. Using this model, the contact melting and evaporation width, erosion depth, erosion rate, and erosion mass are calculated when Ag and AgW30 and AgW70 alloys are used as contact materials. The influence of W-content on the erosion characteristics of a contact is analyzed. The results show that, although the introduction of element W significantly reduces the erosion mass, it advances the time when the melting point and boiling point are reached. The position, width, and depth of the melting pool and melting layer thickness change with the movement of the arc. In the process of contact erosion considering the movement of the arc, the introduction of W element will increase the width of the molten pool and the solidification time of the molten material. Especially when the mass percentage of element W in the contact material reached 70%, the solidification time of the molten material greatly increased, which weakened the welding resistance of the contact.

Weld morphology and grain growth characteristics of driven moving arc hollow stud welding

During the welding process of hollow studs, several issues can arise, including arc deflection, local non-fusion, welding pores, and cracks. In response to these challenges, a rotating magnetic field device has been developed to enhance the welding arc movement, which in turn improves the joint formation and weld grain growth behavior. According to the results, the arc moves in a periodic manner along the end face of the stud when exposed to a rotating magnetic field, due to the application of the Lorentz force. This leads to an enhanced uniformity of the melting process, a reduction in the occurrence of localized un-fusion and porosity defects, and an overall improvement in the quality of the weld morphology. Under the electromagnetic stirring effect, the undercooling of the molten pool changes and the microalloying elements in high-strength steel diffuse into the welded joint. The microstructure of the welded joint area is transformed into martensite, lower bainite, and needle-like ferrite. Under the action of a rotating magnetic field, the coarse grain in the welded joint is broken and the size is refined from 2.91 μm to 1.48 μm. The number of high-angle grain boundaries increases while the number of low-angle grain boundaries decreases. The shear strength of the joint is improved from 227 MPa to 315 MPa.

Symmetry of the Neck Muscles' Activity in the Electromyography Signal during Basic Motion Patterns.

The activity of muscles during motion in one direction should be symmetrical when compared to the activity of the contralateral muscles during motion in the opposite direction, while symmetrical movements should result in symmetrical muscle activation. The literature lacks data on the symmetry of neck muscle activation. Therefore, this study aimed to analyse the activity of the upper trapezius (UT) and sternocleidomastoid (SCM) muscles at rest and during basic motions of the neck and to determine the symmetry of the muscle activation. Surface electromyography (sEMG) was collected from UT and SCM bilaterally during rest, maximum voluntary contraction (MVC) and six functional movements from 18 participants. The muscle activity was related to the MVC, and the Symmetry Index was calculated. The muscle activity at rest was 23.74% and 27.88% higher on the left side than on the right side for the UT and SCM, respectively. The highest asymmetries during motion were for the SCM for the right arc movement (116%) and for the UT in the lower arc movement (55%). The lowest asymmetry was recorded for extension-flexion movement for both muscles. It was concluded that this movement can be useful for assessing the symmetry of neck muscles' activation. Further studies are required to verify the above-presented results, determine muscle activation patterns and compare healthy people to patients with neck pain.

Theoretical justification of the parameters fle­xible screw conveyor for transportation of grain materials

Goal. Increasing the efficiency of the functioning of flexible screw conveyors by substantiating the parameters of the improved design of the articulated and sectional working body for transporting loose agricultural materials. Methods. Theoretical studies were carried out using the methods of theoretical mechanics and higher mathematics. Theoretical calculations of the obtained analytical dependencies and construction of graphical dependencies were performed on a PC using developed programs in the Delphi and SolidWorks software environments. Results. To ensure the correct functioning of the hinge assembly, a study of its design parameters was carried out, which provides mutual rotation, the necessary angular displacement of the axes and the absence of jamming. An analytical relationship is derived for determining the arc movement of the ball along both friction surfaces, the speed of movement of each ball along the arc of the spherical sleeve, and the coefficient of practical action of the hinge and the torque on the drive shaft. Based on the obtained theoretical dependencies, a Pascal program was created in the Delphi environment, and calculations and analysis of the change in the efficiency of the hinge mechanism were performed depending on the main design parameters: the ratio of the radii of the ball and the cylindrical sleeve at the point of contact, the angle of deviation of the hinge axes, the angle of the conical surface holes To choose rational design parameters of the sections of the screw working body, computer modelling of the influence of power loads on the corresponding deformations depending on their operating conditions was carried out. Conclusions. It was established that the transmission efficiency ratio has a maximum value within the range of 0.89...0.93 at a radius ratio of 0.2...0.4. To determine the working area of a particular joint, it is necessary to use design parameters in which the value of the coefficient of practical action is not less than 0.9. The calculation shows that increasing the angle of the hole’s cone reduces the mechanism’s efficiency. It is advisable to choose the ratio of the radii of the ball and the cylindrical sleeve as large as possible for constructive reasons, not less than 0.3. The angle of inclination of the conical surface of the hole should be chosen as minimally as possible, taking into account the selected design scheme of the hinge. In the case of using long conveying screws with a significant number of elements, it is advisable to reduce the angles of deviation of the axes (increase the bending radius of the screw) to improve the overall efficiency of the entire conveyor. A sharp bend in the pipe of the working body, even in one place, can lead to jamming the whole mechanism.

Experimental study on the underwater DC arc behaviors regulated by an external transverse magnetic field

An arc discharge in water can generate extremely high voltage, which has great potential to be used in DC fault protection. The voltage characteristic is closely related to the arc behaviors. However, due to the complexity of the gas–liquid mixed environment, the arc shape is difficult to observe directly. In this letter, an observation device is specially designed and underwater arc motion with millisecond-scale duration is clearly photographed. The corresponding relationship between the arc behaviors and the varied voltage is revealed. Additionally, the random behaviors of underwater arc are controlled stably by applying an external transverse magnetic field. The enhanced cooling mechanism and the directional arc motion characteristics are discussed. We demonstrate that fast elongation of the arc column and continuous heat exchange between phase surfaces are the keys to realizing a rapid increase of underwater arc voltage.

Study of the electric arc dynamics in a cascaded-anode plasma torch

In plasma spraying process, the plasma jet stability depends on the electric arc movement inside the plasma torch. For conventional plasma torches with rod cathode and a large anodic surface, arc roots are free to move along the anode wall, leading to high plasma jet fluctuations. To overcome these instabilities, cascaded-anode plasma torches have been developed, reducing considerably the electric arc movement and thus the plasma jet fluctuations. Unfortunately, a small number of studies reports on the behaviour of theses torches including the arc instabilities and on electrode erosion process as well. In this work, several diagnostics have been set up to further understand the cascaded-anode plasma torch behaviour under different sets of operating conditions. Influence of plasma forming gas composition on the electric arc dynamic has been studied through anodic imaging. The issue of the intense plasma radiation masking is discussed since the light emitted by the arc column interferes with anodic arc roots observations. Multiple constricted arc roots have been observed and a preferential site for anodic arc root has been identified for all experimental conditions. The addition of a secondary plasma forming gas promotes a higher number of reattachments. The influence of the electric arc movement on plasma jet stability is also studied by following the plasma jet brightness fluctuations. The low voltage fluctuation frequency is also observed on brightness spectra, which means that these fluctuations could have an impact on in-flight particle treatment.

Use of a relative motion flexion orthosis with dorsal hood to protect a middle phalanx finger fracture and zone III extensor tendon repair, while correcting a secondary fixed flexion proximal interphalangeal joint flexion contracture: A case report

BackgroundProximal interphalangeal joint (PIPJ) contractures, zone III extensor tendon injuries and phalanx fractures are challenging to treat in isolation. In this case the patient presented with all 3 of these issues in a single digit, presenting a unique problem for the hand therapist. PurposeA case report to examine the effectiveness of using single orthosis to treat an index finger following a combined zone III extension tendon repair, surgically stabilized second phalanx fracture and PIPJ flexion contracture. MethodsA patient presented to therapy with a 40° PIPJ flexion contracture and minus 70° of active PIPJ extension (ICD10 M25.64) after left index surgical fixation of a middle phalanx fracture (ICD10 S62.621B) and zone III extensor tendon repair (ICD10 S66.321A). To correct the contracture, a distal elastic strap was added to a relative motion flexion orthosis with dorsal hood. This applied a gentle extension force to the PIPJ. Once the contracture resolved a short arc motion program (SAM) was initiated using the same orthosis. ResultsAt 20 weeks post initial therapy evaluation, active range of motion (extension/flexion) of the PIPJ was 5°/100° and distal interphalangeal joint (DIPJ) 0°/60°. The Quick DASH score improved 50 points from an initial 59 points to 9 points. The patient reported good satisfaction and full function of the hand. ConclusionOur case report demonstrated the effective use of a single relative motion flexion orthosis with a dorsal hood when treating a complex hand injury involving an open zone III injury, second phalanx fracture and 40-degree PIPJ contracture.

Study on magnetically blown arc characteristics and the resulting contact erosion mechanisms of high-power DC relays

High-power DC relays are widely used in new energy power systems and DC distribution networks, and commonly use transverse magnetic fields to accelerate arc extinguishing. In this paper, the magnetically blown arc characteristics and the resulting contact erosion mechanisms of high-power DC relays are studied by experiments and simulations. The experiments are carried out to analyze the arc motion, contact erosion mass, and contact morphologies, and to verify the simulation model. Considering the energy transfer source term, the establishment of a more perfect magnetohydrodynamic arc model is accomplished, and an erosion model is further established. The results indicate that the magnetically blown arcing process has three stages while the arc shapes and motion characteristics are different, and the heat flux acting on the contact can be accurately obtained by the arc model. The greater external transverse magnetic field is more conducive to extinguishing the arc and reducing the arc erosion time. In contrast, the Archimedes force plays a very small positive role and the self-induced magnetic field of the arc has a negative effect. For contact erosion, the temperature distribution of the molten pool appears trailing effect. Moreover, the advanced mathematical model proposed for erosion mass has good accuracy. The calculation results of erosion rates show that Cr reduces erosion while the current increases erosion nonlinearly. Besides, the flow and deformation characteristics of the molten pool will lead to convex strip-shaped erosion traces and arcing position transfer, and the moving erosion will cause the lateral accretion effect. Furthermore, the analysis shows that the reason for edge droplet sputtering is the pressure difference caused by Plateau–Rayleigh instability, and optimization suggestions for reducing contact erosion are given.

New Insight Into the Transition From a SAR Arc to STEVE

AbstractIn this study, we present an analysis of the spectral transition of a Stable Auroral Red (SAR) arc to Strong Thermal Emission Velocity Enhancement (STEVE) emission observed by the Transition Region Explorer (TREx) Spectrograph on the night of 10 April 2022, recorded overhead in Lucky Lake, Saskatchewan. On this night, we see an unusually bright (∼2 kR) SAR arc with enhanced ionospheric flow channels in the conjugate southern hemisphere. Over a short time, on the order of minutes, we observe the spectra change from the typical SAR arc pure redline (630 and 636 nm) emission to the air glow continuum, a broadband enhancement across all wavelengths, characteristic of STEVE. We propose the presence of threshold conditions required for the SAR arc to evolve into STEVE. In addition, we present parameters such as transition times, luminosities, and arc motion to be applied to ionospheric models.