The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
I I Beilis - One of the best experts on this subject based on the ideXlab platform.
-
gasdynamic theory of Cathode Spot mathematically closed formulation
2020Co-Authors: I I BeilisAbstract:According to the considered analysis in above chapters, the Cathode Spot is a complicated subject that is difficult to investigate not only experimentally, but also hardly studied theoretically. Therefore, the previously involved approaches used arbitrary parameters that are preferable to calculate. The main problem consists in perception for long time by the researches that the Cathode Spot is completely non-equilibrium formation and of extremely material state, which cannot be considered by traditional approaches [1]. The goal of any complete Spot theory is to indicate mechanism that can determine the difference between non-equilibrium and equilibrium regions and to understand the charge particles’ motion near the surface.
-
Cathode Spot motion in a transverse and in an oblique magnetic field
2020Co-Authors: I I BeilisAbstract:Different aspects of experimental investigation of Cathode Spot motion in a vacuum arc under transverse- and oblique-oriented magnetic fields will be reviewed and analyzed.
-
Cathode Spot theories history and evolution of the mechanisms
2020Co-Authors: I I BeilisAbstract:An electrical discharge in vacuum or in low pressure ambient gas can be supported if enough charge particles are generated in the electrode gap. The main question is continuity of the electrical current from the metallic Cathode to an electro-conductive media in the gap. The problem is the current transition from the high conductive metallic Cathode to relatively low conductive gap plasma. According to the experiment, this transition proceeds by the strong plasma contraction at the Cathode surface in the form of so-called Cathode Spot.
-
mechanism of Cathode Spot splitting in vacuum arcs in an oblique magnetic field
Physics of Plasmas, 2015Co-Authors: I I BeilisAbstract:Experiments in the last decade showed that for Cathode Spots in a magnetic field that obliquely intercepts the Cathode surface, the current per Spot increased with the transverse component of the magnetic field and decreased with the normal component. The present work analyzes the nature of Cathode Spot splitting in an oblique magnetic field. A physical model for Cathode Spot current splitting was developed, which considered the relation between the plasma kinetic pressure, self-magnetic pressure, and applied magnetic pressure in a current carrying Cathode plasma jet. The current per Spot was calculated, and it was found to increase with the tangential component of the magnetic field and to decrease with the normal component, which agrees well with the experimental dependence.
-
Cathode Spot motion in a vacuum arc with a long roof shaped Cathode under magnetic field
Journal of Applied Physics, 2015Co-Authors: I I Beilis, B Sagi, V N Zhitomirsky, R L BoxmanAbstract:Vacuum arc Cathode Spot motion was investigated on a “roof-shaped” aluminum Cathode under an external magnetic field. The Cathode included a flat roof-top and four sloped sides, inclined by an angle α. A high speed camera was used to observe Cathode Spot motion. The Spot velocity on the slopes and the distribution of Cathode Spots on the roof and slopes was determined. It was obtained that under a magnetic field, the Spot motion on the roof was slow (<1 m/s) and mainly random, while on the slopes fast retrograde motion was observed. This velocity increased linearly with the magnetic field and decreased slightly with α.
Lijun Wang - One of the best experts on this subject based on the ideXlab platform.
-
simulation of Cathode Spot crater formation and development on cucr alloy in vacuum arc
Physics of Plasmas, 2018Co-Authors: Lijun Wang, Xiao Zhang, Yuan Wang, Ze Yang, Shenli JiaAbstract:The two-dimensional (2D) rotary axisymmetric model is used to describe the formation and development of a Cathode Spot on a copper-chromium alloy (CuCr) in a vacuum arc. The model includes hydrodynamic equations and the heat transfer equation. Parameters used in this model come from experiments and other researchers' work. The influence of parameters is analyzed, and the simulation results are compared with pure metal simulation results. In simulation, the depth of the Cathode crater is from 0.5 μm to 1.1 μm, the radius of the Cathode crater is from 1.6 μm to 2.6 μm, the maximum velocity of the droplet is from 200 m/s to 600 m/s, and the maximum temperature is from 3500 K to 5000 K which is located in the area with a radius of 0.5–1.5 μm. The simulation results show that a smooth Cathode surface is advantageous for reducing ablation, the ablation on the CuCr alloy is smaller than that on the pure metal Cathode electrode, and the Cathode Spot appears on the chromium grain only on CuCr. The simulation results are in good agreement with the experiment.The two-dimensional (2D) rotary axisymmetric model is used to describe the formation and development of a Cathode Spot on a copper-chromium alloy (CuCr) in a vacuum arc. The model includes hydrodynamic equations and the heat transfer equation. Parameters used in this model come from experiments and other researchers' work. The influence of parameters is analyzed, and the simulation results are compared with pure metal simulation results. In simulation, the depth of the Cathode crater is from 0.5 μm to 1.1 μm, the radius of the Cathode crater is from 1.6 μm to 2.6 μm, the maximum velocity of the droplet is from 200 m/s to 600 m/s, and the maximum temperature is from 3500 K to 5000 K which is located in the area with a radius of 0.5–1.5 μm. The simulation results show that a smooth Cathode surface is advantageous for reducing ablation, the ablation on the CuCr alloy is smaller than that on the pure metal Cathode electrode, and the Cathode Spot appears on the chromium grain only on CuCr. The simulation resul...
-
Stepwise Simulation on the Robson Drift of a Single Cathode Spot of Vacuum Arc
2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV), 2018Co-Authors: Zongqian Shi, Shenli Jia, Xin Liu, Lijun WangAbstract:The Robson drift phenomenon is a macroscopic reflection of the movement of a Cathode Spot in oblique magnetic field. Although it was discovered many years ago, its physical mechanism remains unclear. In this paper, the influence of oblique magnetic field on the Robson drift of Cathode Spot motion is studied. A two-dimensional stepwise model of the movement of a single Cathode Spot in oblique magnetic field is established. It's assumed that the probability of generating a new Spot in directions of Amperian force, anti-Amperian force, and directions perpendicular to Amperian force, are proportional to the magnetic pressure around the old Spot. The drift angle of the Cathode Spot in oblique magnetic field is simulated. The simulation results show that the drift angle of the Cathode Spot in oblique magnetic field has linear relationship with the magnetic field inclination angle, and that the lateral jet has an important influence on the Robson drift phenomenon.
-
modeling of Cathode Spot crater formation and development in vacuum arc
Journal of Physics D, 2017Co-Authors: Xiao Zhang, Lijun Wang, Dmitry L. ShmelevAbstract:A two-dimensional (2D) rotary axisymmetric model has been developed to describe the formation and development of Cathode Spot in vacuum arc. The model includes hydrodynamic equations and heat transfer equation which considers surface evaporation and Joule heating. Parameters used in this model, such as the distributions of pressure, energy flux density, and current density, come from experiments and other researchers' work. In this model, Cathode Spot maintains 30 ns and during this time, all parameters are fixed. The simulation results show that when the energy flux density is 1.5–3 × 1012 W, discharge current is 1–6 A and the pressure is 1–3 × 108 Pa, the crater radius is 1.4–4.1 µm, the crater depth is 1.4–2.1 µm, the velocity of liquid metal is 154–428 m s−1 and the maximum temperature is 2145–5342 K which is located in the area with radius 0.5–1.5 µm. Besides, on the chromium Cathode, the maximum temperature is higher mainly because of the lower thermal conductivity.
-
The Motion Characteristics of a Single Cathode Spot in Removing Oxide Layer on Metal Surface by Vacuum Arc
IEEE Transactions on Plasma Science, 2017Co-Authors: Zongqian Shi, Shenli Jia, Cong Wang, Fei Shi, Lijun WangAbstract:The motion of Cathode Spots plays a crucial important role in removing oxide layer on a metal surface by vacuum arc. In this paper, the characteristics of the motion of a single Cathode Spot on metal surface with oxide layer are investigated experimentally. Experiments are conducted in a detachable vacuum chamber. A hollow copper anode with a hole of $10~\text {mm} \times 10$ mm is used in order to observe the 2-D motion of the Cathode Spot. The motion of the Cathode Spot during the descaling process is photographed by a high-speed digital camera with an exposure time of $2~\mu \text{s}$ . Experimental results indicate that there are slow motion and fast motion of the Cathode Spot during descaling process, and the slow motion is the basic characteristic in most of the descaling time. The probability distribution of the Cathode Spot’s displacement and resident time, the average velocity, and the movement parameter $S^{2}/t$ are analyzed quantitatively. The results indicate that with the increase of gap distance or the decrease of oxide layer thickness, the Cathode Spot becomes more active.
-
Modeling of mixing and interaction of multi-Cathode Spot vacuum arc jets
AIP Advances, 2016Co-Authors: Lijun Wang, Jie Deng, Kang Qin, Shenli JiaAbstract:Vacuum arc consists of Cathode Spot and mixing zone, arc column and anode zone. The separate jets and the mixing zone should be considered in the model of diffuse arc. Moreover, the interaction between the plasma jets in multi-Cathode Spot vacuum arc also is very important. In this paper, mixing and interaction of multi-Cathode Spot vacuum arc jets were studied through simulation. To completely investigate the mixing and interaction of vacuum arc jets, a steady 3D Magneto-Hydro-Dynamic (MHD) modeling was established. In order to find out the influence of different parameters on mixing and interaction of vacuum arc jets, simulations with different parameters such as currents, angel of vacuum arc jets, with or without electromagnetic equations, tilted jets and different height of mixing zone were conducted. The simulation results show that the densities of ion number and plasma pressure as well as ion temperature increase with the increase of arc current, while the plasma velocity decreases. The jet center ...
Shenli Jia - One of the best experts on this subject based on the ideXlab platform.
-
simulation of Cathode Spot crater formation and development on cucr alloy in vacuum arc
Physics of Plasmas, 2018Co-Authors: Lijun Wang, Xiao Zhang, Yuan Wang, Ze Yang, Shenli JiaAbstract:The two-dimensional (2D) rotary axisymmetric model is used to describe the formation and development of a Cathode Spot on a copper-chromium alloy (CuCr) in a vacuum arc. The model includes hydrodynamic equations and the heat transfer equation. Parameters used in this model come from experiments and other researchers' work. The influence of parameters is analyzed, and the simulation results are compared with pure metal simulation results. In simulation, the depth of the Cathode crater is from 0.5 μm to 1.1 μm, the radius of the Cathode crater is from 1.6 μm to 2.6 μm, the maximum velocity of the droplet is from 200 m/s to 600 m/s, and the maximum temperature is from 3500 K to 5000 K which is located in the area with a radius of 0.5–1.5 μm. The simulation results show that a smooth Cathode surface is advantageous for reducing ablation, the ablation on the CuCr alloy is smaller than that on the pure metal Cathode electrode, and the Cathode Spot appears on the chromium grain only on CuCr. The simulation results are in good agreement with the experiment.The two-dimensional (2D) rotary axisymmetric model is used to describe the formation and development of a Cathode Spot on a copper-chromium alloy (CuCr) in a vacuum arc. The model includes hydrodynamic equations and the heat transfer equation. Parameters used in this model come from experiments and other researchers' work. The influence of parameters is analyzed, and the simulation results are compared with pure metal simulation results. In simulation, the depth of the Cathode crater is from 0.5 μm to 1.1 μm, the radius of the Cathode crater is from 1.6 μm to 2.6 μm, the maximum velocity of the droplet is from 200 m/s to 600 m/s, and the maximum temperature is from 3500 K to 5000 K which is located in the area with a radius of 0.5–1.5 μm. The simulation results show that a smooth Cathode surface is advantageous for reducing ablation, the ablation on the CuCr alloy is smaller than that on the pure metal Cathode electrode, and the Cathode Spot appears on the chromium grain only on CuCr. The simulation resul...
-
Stepwise Simulation on the Robson Drift of a Single Cathode Spot of Vacuum Arc
2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV), 2018Co-Authors: Zongqian Shi, Shenli Jia, Xin Liu, Lijun WangAbstract:The Robson drift phenomenon is a macroscopic reflection of the movement of a Cathode Spot in oblique magnetic field. Although it was discovered many years ago, its physical mechanism remains unclear. In this paper, the influence of oblique magnetic field on the Robson drift of Cathode Spot motion is studied. A two-dimensional stepwise model of the movement of a single Cathode Spot in oblique magnetic field is established. It's assumed that the probability of generating a new Spot in directions of Amperian force, anti-Amperian force, and directions perpendicular to Amperian force, are proportional to the magnetic pressure around the old Spot. The drift angle of the Cathode Spot in oblique magnetic field is simulated. The simulation results show that the drift angle of the Cathode Spot in oblique magnetic field has linear relationship with the magnetic field inclination angle, and that the lateral jet has an important influence on the Robson drift phenomenon.
-
The Motion Characteristics of a Single Cathode Spot in Removing Oxide Layer on Metal Surface by Vacuum Arc
IEEE Transactions on Plasma Science, 2017Co-Authors: Zongqian Shi, Shenli Jia, Cong Wang, Fei Shi, Lijun WangAbstract:The motion of Cathode Spots plays a crucial important role in removing oxide layer on a metal surface by vacuum arc. In this paper, the characteristics of the motion of a single Cathode Spot on metal surface with oxide layer are investigated experimentally. Experiments are conducted in a detachable vacuum chamber. A hollow copper anode with a hole of $10~\text {mm} \times 10$ mm is used in order to observe the 2-D motion of the Cathode Spot. The motion of the Cathode Spot during the descaling process is photographed by a high-speed digital camera with an exposure time of $2~\mu \text{s}$ . Experimental results indicate that there are slow motion and fast motion of the Cathode Spot during descaling process, and the slow motion is the basic characteristic in most of the descaling time. The probability distribution of the Cathode Spot’s displacement and resident time, the average velocity, and the movement parameter $S^{2}/t$ are analyzed quantitatively. The results indicate that with the increase of gap distance or the decrease of oxide layer thickness, the Cathode Spot becomes more active.
-
Modeling of mixing and interaction of multi-Cathode Spot vacuum arc jets
AIP Advances, 2016Co-Authors: Lijun Wang, Jie Deng, Kang Qin, Shenli JiaAbstract:Vacuum arc consists of Cathode Spot and mixing zone, arc column and anode zone. The separate jets and the mixing zone should be considered in the model of diffuse arc. Moreover, the interaction between the plasma jets in multi-Cathode Spot vacuum arc also is very important. In this paper, mixing and interaction of multi-Cathode Spot vacuum arc jets were studied through simulation. To completely investigate the mixing and interaction of vacuum arc jets, a steady 3D Magneto-Hydro-Dynamic (MHD) modeling was established. In order to find out the influence of different parameters on mixing and interaction of vacuum arc jets, simulations with different parameters such as currents, angel of vacuum arc jets, with or without electromagnetic equations, tilted jets and different height of mixing zone were conducted. The simulation results show that the densities of ion number and plasma pressure as well as ion temperature increase with the increase of arc current, while the plasma velocity decreases. The jet center ...
-
stepwise simulation on the motion of a single Cathode Spot of vacuum arc in external transverse magnetic field
IEEE Transactions on Plasma Science, 2015Co-Authors: Zongqian Shi, Shenli Jia, Cong Wang, Xiaochuan Song, Lijun WangAbstract:In this paper, the relationship between the external transverse magnetic field (TMF) and the ignition probability of new Cathode Spot in different directions is developed assuming that the ignition probability of a new Cathode Spot is proportional to the magnetic pressure around the old one. Furthermore, a method is established to simulate the 2-D motion of a Cathode Spot step-by-step. With this approach, stepwise simulations of the 2-D retrograde motion of a single Cu Cathode Spot are carried out in a large range of flux density of TMF ( ${B}_{\rm {em}}$ ). Simulation results indicate that, if the self-generated magnetic field ${B}_{\rm {sm}}$ exceeds the applied magnetic field ${B}_{\rm {em}}$ , i.e., ${B}_{\textrm {em}}\le {B}_{\rm {sm}}$ , there is a linear relationship between the velocity of the retrograde motion and ${B}_{\rm {em}}$ , in certain range of ${B}_{\rm {em}}$ , after which the velocity of the retrograde motion increases slowly and nonlinearly with further increase of ${B}_{\textrm {em}}$ . This phenomenon agrees well with relevant experiment results. In the linear stage, the dependence of velocity constant on the spatial step and the temporal step of the motion of Cathode Spot is investigated as well. Moreover, when ${B}_{\rm {em}}>{B}_{\rm {sm}}$ , the velocity of Cathode Spot decreases with the increase of ${B}_{\textrm {em}}$ , even the macroscopic motion is still in the retrograde direction. This effect might also contribute to the reversal of Cathode Spot motion from the retrograde direction to the Amperian direction at strong TMF besides the predominant effect of the deflection of arc column toward the Amperian direction.
Isak I. Beilis - One of the best experts on this subject based on the ideXlab platform.
-
Vacuum Arc Cathode Spot Theory: History and Evolution of the Mechanisms
IEEE Transactions on Plasma Science, 2019Co-Authors: Isak I. BeilisAbstract:Vacuum arc Cathode Spot theories are reviewed, beginning from the primary studies in second half of the 19th century up to the present. The evolution of the main ideas is presented, starting from those, which developed, for separate phenomena, up to systematic inclusive models. New Spot type classifications are proposed based on observed characteristics, instead of the previous simple numbering. Different approaches were considered for generating plasma comprised of Cathode material, based on Cathode vaporization and local explosions. Models with closed systems of equations were developed. A kinetic model advantageously allows calculating the Cathode potential drop. These closed models explain various phenomena and two base rules were derived: 1) impeded plasma flow enables Cathode Spot operation and 2) the heat loss in the Cathode must be smaller than the energy input to the Cathode Spot. Based on these rules, mechanisms for the Spot types were derived and observed Spot behavior in transverse and oblique magnetic fields was described.
-
Vacuum Arc Cathode Spot Theory. History and Evolution of the Mechanisms
2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV), 2018Co-Authors: Isak I. BeilisAbstract:Vacuum arc Cathode Spot theories are reviewed, beginning from the primary studies in second half of 19th century and in the beginning of 20th century up to the present. The evolution of the main ideas is presented, starting from those which developed for separate phenomena, up to systematic inclusive models. Different approaches were considered for generating a plasma comprised of Cathode material, based on Cathode vaporization and local explosions. Models with closed systems of equations were developed. A kinetic model advantageously allows calculating the Cathode potential drop. These closed models explain various phenomena and Spot types, based on two principals: (1) impeded plasma flow enables Cathode Spot operation, and (2) the heat loss in the Cathode must be smaller than the energy input to the Cathode Spot.
-
Vacuum arc Cathode Spot motion in oblique magnetic fields: An interpretation of the Robson experiment
Physics of Plasmas, 2016Co-Authors: Isak I. BeilisAbstract:A model was developed of vacuum arc Cathode Spot motion in a magnetic field that obliquely intercepts the Cathode surface. The model takes into account a force under an electric field caused by retrograde Spot motion across the normal component of the magnetic field, producing a drift velocity component in the direction of the acute angle between the magnetic field and the Cathode surface. The relationship between velocity of the retrograde direction and drift velocity of the Cathode Spot motion to the acute angle was developed. The dependencies of the drift angle θ on the acute angle φ, magnetic field strength B, and arc current I were calculated. It was found that the calculated θ increased with φ, B, and I in accordance with Robson's measurements.
-
A model of vacuum arc Cathode Spot motion in an oblique magnetic field
2016 27th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV), 2016Co-Authors: Isak I. BeilisAbstract:A model of vacuum arc Cathode Spot motion in a magnetic field which obliquely intercepts the Cathode surface was developed. The model takes in account an electrical force generated by Spot motion across the normal component of the magnetic field, which accelerates plasma in the direction of the opening of the acute angle. A relation between the drift angle (between the retrograde direction and the Cathode Spot motion) and the acute angle formed by the intersection of the magnetic field lines with the Cathode surface, was developed. The dependencies of the drift angle on the acute angle and magnetic field strength measured in Robson's experiment were analyzed.
-
Theoretical Modeling of Cathode Spot Phenomena
Handbook of Vacuum Arc Science and Technology, 1996Co-Authors: Isak I. BeilisAbstract:Publisher Summary The chapter focuses on bringing together the various phenomena and processes occurring in the vicinity of the Cathode Spot and described separately in section "General Theory" into a single, unified theoretical model. It analyzes several cases requiring a different approach, including Cathode materials having extreme thermo-physical properties (highly refractive or highly volatile), and Cathodes having special surface geometries, such as protrusions and thin films. The Cathode Spot vicinity may be divided into several zones, where the material in each zone can be described by a common set of equations. The first zone is the Cathode itself, in which the matter is in a condensed state. In most cases, the material far from the Cathode Spot is solid, while close to the Cathode Spot the material is molten. The particles emitted from the Cathode surface travel some short distance in the ballistic zone before suffering collisions, a distance which is defined by the mean free path. The ballistic zone is a collisionless sheath in which the motion of the various particles can be described by collisionless equations. A strong electric field is present within the ballistic zone, which accelerates the electrons away from the Cathode. In addition to the particles emitted from the Cathode, the ballistic zone is transversed by a back flow of electrons and ions from the other regions. Atoms emitted from the Cathode surface collides with each other and with the back flow of heavy particles, in the heavy particle relaxation zone, which begins at the Cathode, overlaps the ballistic zone, and extends a distance of a few times the heavy particle mean free path. Whereas the heavy particles emitted from the Cathode surface have a uni-directional velocity distribution, i.e., all the emitted particles have a positive normal velocity component, at the far end of the heavy particle relaxation zone. Joule heating, and thermal conduction cooling are the two primary processes that occur within the Cathode bulk.
Sergey A. Barengolts - One of the best experts on this subject based on the ideXlab platform.
-
Pre-Explosion Phenomena Beneath the Plasma of a Vacuum Arc Cathode Spot
IEEE Transactions on Plasma Science, 2015Co-Authors: Sergey A. Barengolts, Dmitry L. Shmelev, Igor V. UimanovAbstract:A 2-D hydrodynamic model has been developed that describes the pre-explosion processes in a microprotrusion of a vacuum arc Cathode based on a self-consistent calculation of the electric potential drop in the near-Cathode region. The model includes a calculation of the Cathode temperature in view of the surface heat fluxes carried by electrons and ions during the interaction of the Cathode surface with the Cathode Spot plasma and the Joule heating of the Cathode. The near-Cathode space charge sheath is considered in the 1-D local Bohm approximation. It has been shown that the heat flux from a Cathode plasma having parameters characteristic of low-current vacuum arcs can induce thermal instability (thermal runaway) in a Cathode microprotrusion and heat it to a critical temperature within some tens of nanoseconds. Comparative analysis of the volumetric Joule mechanism and the surface electron-plasma mechanism underlying the development of thermal instabilities in a Cathode has been performed in one numerical experiment. It has been shown that the instability induced by the surface mechanism can arise at lower densities of the Cathode Spot plasma and its growth rate is lower compared with the instability induced by the Joule mechanism.
-
On the mechanism of operation of a Cathode Spot cell in a vacuum arc
Applied Physics Letters, 2014Co-Authors: G. A. Mesyats, Maxim B. Bochkarev, A. A. Petrov, Sergey A. BarengoltsAbstract:The erosive structures formed on a tungsten Cathode as a result of the motion of the Cathode Spot of a vacuum arc over the Cathode surface have been examined. It has been found that the average mass of a Cathode microprotrusion having the shape of a solidified jet is approximately equal to the mass of ions removed from the Cathode within the lifetime of a Cathode Spot cell carrying a current of several amperes. The time of formation of a new liquid-metal jet under the action of the reactive force of the plasma ejected by the Cathode Spot is about 10 ns, which is comparable to the lifetime of a cell. The growth rate of a liquid-metal jet is ∼104 cm/s. The geometric shape and size of a solidified jet are such that a new explosive emission center (Spot cell) can be initiated within several nanoseconds during the interaction of the jet with the dense Cathode plasma. This is the underlying mechanism of the self-sustained operation of a vacuum arc.
-
effect of tangential magnetic field on ecton processes in Cathode Spot of vacuum arc
Technical Physics Letters, 2010Co-Authors: Dmitry L. Shmelev, Sergey A. Barengolts, V G MesyatsAbstract:Emission and erosion processes involved in the final stage of the Cathode Spot cell operation in vacuum arc in the presence of an external magnetic field have been numerically simulated. It is established that the application of a magnetic field leads to asymmetry in the distributions of current density and heat flux, so that their maxima shift in the “anti-Ampere” direction. For more detailed analysis of the phenomenon of retrograde motion of the Cathode Spot in a magnetic field, it is necessary to study the behavior of a liquid metal phase in the Spot.
-
The Cathode Spot of a high-current vacuum arc as a multiecton phenomenon
IEEE Transactions on Plasma Science, 2001Co-Authors: G. A. Mesyats, Sergey A. BarengoltsAbstract:The operation of the Cathode Spot of a high-current vacuum arc is treated in terms of the ecton model. It has been demonstrated that, in this case, the Cathode Spot cells are grouped to adjoin one another. The existence of such,a collective Spot is due to the cumulative effect of a number of microexplosions, resulting in that the current density in the Spot increases by-almost an order of magnitude. Moreover, in such a Spot, conditions are realized which are energetically profitable for the repetition of ecton processes, namely, an elevated temperature of the surface and an increased density of the near-Cathode plasma. The parameters of a collective Cathode Spot, such as the crater diameter, the current density, and the lifetime, have been related to the arc current. The predicted relationships are in good agreement with experimental results. It has been shown that as the arc current increases, the current density in the Cathode Spot drops, resulting in division of the Spot. An estimate of the limiting arc current per unit Spot has been obtained.
-
Motion of the Cathode Spot of a vacuum arc in an external magnetic field
Technical Physics, 1998Co-Authors: Sergey A. Barengolts, E.y. Sadovskaya, E. A. Litvinov, Dmitry L. ShmelevAbstract:The problem of the motion of the Cathode Spot of a vacuum arc electrical discharge in a magnetic field applied tangential to the Cathode surface is considered. The treatment is based on concepts of the nonstationary, cyclical nature of processes occurring in the Cathode Spot and the key role of return electrons falling out of the near-Cathode plasma back onto the Cathode.