The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Andre Anders - One of the best experts on this subject based on the ideXlab platform.
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the evolution of ion charge states in cathodic Vacuum Arc plasmas a review
Plasma Sources Science and Technology, 2012Co-Authors: Andre AndersAbstract:Cathodic Vacuum Arc plasmas are known to contain multiply charged ions. Twenty years after ‘Pressure ionization: its role in metal vapour Vacuum Arc plasmas and ion sources’ appeared in volume 1 of Plasma Sources Science and Technology, this is a great opportunity to re-visit the issue of pressure ionization, a non-ideal plasma effect, and put it in perspective to the many other factors that influence observable charge state distributions, such as the role of the cathode material, the path in the density–temperature phase diagram, the ‘noise’ in Vacuum Arc plasma as described by a fractal model approach, the effects of external magnetic fields and charge exchange collisions with neutrals. A much more complex image of the Vacuum Arc plasma emerges, putting decades of experimentation and modeling in perspective.
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a theoretical analysis of Vacuum Arc thruster and Vacuum Arc ion thruster performance
IEEE Transactions on Plasma Science, 2008Co-Authors: James E. Polk, M J Sekerak, Jacquie Schein, N. Qi, John K. Ziemer, Andre AndersAbstract:Thrusters that exploit Vacuum Arc discharges to produce high-velocity plasma jets directly or as sources of plasma that is subsequently accelerated electrostatically have been proposed or are currently under development. Vacuum Arc discharges exhibit certain regularities in their behavior that allow the performance of these thrusters to be described by simple semiempirical models. Empirical data on the current density distribution, charge state and velocity of ions created in Vacuum Arc discharges, and the total cathode mass loss rate are used to develop expressions for the expected thrust and specific impulse as a function of thruster geometry. Thruster electrical efficiency and thrust-to-power ratio are calculated based on measurements of the burning voltage for given thruster operating parameters. Estimates of achievable thruster performance for a wide range of cathode materials are presented. This analysis suggests that thrusters using Vacuum Arc sources can be operated efficiently with a range of propellant options that gives great flexibility in specific impulse. In addition, the efficiency of plasma production in these devices appears to be largely independent of scale because the metal vapor is ionized within tens of micrometers of the cathode electron emission sites, so this approach is well suited for micropropulsion.
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inductive energy storage driven Vacuum Arc thruster
Review of Scientific Instruments, 2002Co-Authors: J. Schein, James E. Polk, M Krishnan, John Ziemer, R. Binder, Andre AndersAbstract:A new type of Vacuum Arc thruster in combination with an innovative power processing unit (PPU) has been developed that promises to be a high efficiency (∼15%), low mass (∼100 g) propulsion system for micro- and nanosatellites. This thruster accelerates a plasma that consists almost exclusively of ions of the cathode material and has been operated with a wide variety of cathodes. The streaming velocity of the plasma exhaust varies with cathode material, from a low of 11 km/s for Ti up to 30 km/s for Al, with a corresponding range of specific impulse from 1100 s for Ta to 3000 s for Al. Initiation of the Arc requires only a few hundred volts due to an innovative “triggerless” approach in which a conductive layer between the cathode and the anode produces the initial charge carriers needed for plasma production. The initial starting voltage spike as well as the energy to operate the Vacuum Arc are generated by a low mass (<300 g) inductive energy storage PPU which is controlled using +5 V level signals. The thrust-to-power ratio has been estimated to reach up to ≈20 μN/W. The Vacuum Arc thruster was tested at the Jet Propulsion Laboratory using W as cathode material. Experimental results are within 65% of the estimated values.
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A theoretical analysis of Vacuum Arc thruster performance
2001Co-Authors: James E. Polk, M J Sekerak, Jochen Schein, John Ziemer, R. Binder, Andre AndersAbstract:In Vacuum Arc discharges the current is conducted through vapor evaporated from the cathode surface. In these devices very dense, highly ionized plasmas can be created from any metallic or conducting solid used as the cathode. This paper describes theoretical models of performance for several thruster configurations which use Vacuum Arc plasma sources. This analysis suggests that thrusters using Vacuum Arc sources can be operated efficiently with a range of propellant options that gives great flexibility in specific impulse. In addition, the efficiency of plasma production in these devices appears to be largely independent of scale because the metal vapor is ionized within a few microns of the cathode electron emission sites, so this approach is well-suited for micropropulsion.
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ion velocities in Vacuum Arc plasmas
Journal of Applied Physics, 2000Co-Authors: George Yu Yushkov, E. M. Oks, Andre Anders, I G BrownAbstract:Ion velocities in Vacuum Arc plasmas have been measured for most conducting elements of the Periodic Table. The method is based on drift time measurements via the delay time between Arc current modulation and ion flux modulation. A correlation has been found between the element-specific ion velocity and average ion charge state; however, differently charged ions of the same element have approximately the same velocity. These findings contradict the potential hump model but are in agreement with a gasdynamic model that describes ion acceleration as driven by pressure gradients and electron-ion friction. The differences between elements can be explained by the element-specific power density of the cathode spot plasma which in turn determines the temperature, average charge state, and ion velocity of the expanding Vacuum Arc plasma.
Shenli Jia - One of the best experts on this subject based on the ideXlab platform.
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Modeling of CuCr contact Vacuum Arc with consideration of its components
AIP Advances, 2018Co-Authors: Jie Deng, Lijun Wang, Xiao Zhang, Ze Yang, Shenli JiaAbstract:This paper involves the simulation of Vacuum Arc under composite (CuCr) contact. A three dimensional model is developed and we have considered the ionization process as well as recombination in the Vacuum Arc. The species transport equations, in which the fraction of each component is calculated, provides the distribution of various atoms and ions in Vacuum Arc. The model describes ions and atoms as two different processes considering that ions are influenced by self-generated magnetic field. Atoms play an inferior role in the process of Vacuum Arc. They gather in an ‘atom layer’ whose thickness is no more than 1mm and outside the atom layer the density of atoms declines by at most 5 orders of magnitude. The ionization process is dominated by electron temperature. The distribution of ion species is closely related to the degree of ionization. At cathode, singly charged ions are dominant. From cathode to anode, ions are ionized so that doubly charged ions become the major component at anode where singly charged ions reach their minimum density. Finally, the ionization rate is also influenced by the ionization potential of each component, so the fraction of Cr1+ is smaller than Cu1+ while Cr2+ is larger than Cu2+ in the anode center.This paper involves the simulation of Vacuum Arc under composite (CuCr) contact. A three dimensional model is developed and we have considered the ionization process as well as recombination in the Vacuum Arc. The species transport equations, in which the fraction of each component is calculated, provides the distribution of various atoms and ions in Vacuum Arc. The model describes ions and atoms as two different processes considering that ions are influenced by self-generated magnetic field. Atoms play an inferior role in the process of Vacuum Arc. They gather in an ‘atom layer’ whose thickness is no more than 1mm and outside the atom layer the density of atoms declines by at most 5 orders of magnitude. The ionization process is dominated by electron temperature. The distribution of ion species is closely related to the degree of ionization. At cathode, singly charged ions are dominant. From cathode to anode, ions are ionized so that doubly charged ions become the major component at anode where singly ch...
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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 ...
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Modeling and simulation of mixing and interaction of multi-cathode spot Vacuum Arc jets
2016 27th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV), 2016Co-Authors: Kang Qin, Lijun Wang, Jie Deng, 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 Vacuum Arc, especially the diffuse Arc. In this paper, mixing and interaction of multi-cathode spot Vacuum Arc jets were studied through simulation. To investigate the mixing and interaction of Vacuum Arc jets a steady 3D Magneto-Hydro-Dynamic (MHD) modeling was required. In order to find out the influence of different parameters on mixing and interaction of Vacuum Arc jets, models with different parameters such as currents, angel of Vacuum Arc jets, with or without electromagnetic equations and tilted jets were simulated. Six cylindrical jets were modeled to study the process of mixing and interaction of multi-cathode spot Vacuum Arc jets. Based on the simulation results, the ion number density, temperature distribution, flow velocity and ion pressure were given and analyzed.
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Vacuum Arc under axial magnetic fields: experimental and simulation reseArch
Journal of Physics D: Applied Physics, 2014Co-Authors: Shenli Jia, Zongqian Shi, Lijun WangAbstract:Axial magnetic field (AMF) technology is a most important control method of Vacuum Arc, particularly for high-current Vacuum Arcs in Vacuum interrupters. In this paper, a review of the state of current reseArch on Vacuum Arcs under AMF is presented. The major aspects of Vacuum Arc in an AMF such as Arc voltage, the motion of cathode spots, and anode activities are discussed, and the most recent progress both of experimental and simulation reseArch is presented.
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Simulation of the Thermal Process of Anode in Drawn Vacuum Arc
IEEE Transactions on Plasma Science, 2007Co-Authors: Zongqian Shi, Shenli Jia, Hong Dong, Lijun WangAbstract:In this paper, a transient 2-D finite-element model was developed to simulate the anode activities of drawn Vacuum Arc. Some important thermal processes of anode, e.g., the temperature distribution, melt, and evaporation, have been investigated for copper Vacuum Arc of 27.5 kA (rms) with different separation current. The dimension of eroded region on anode due to melt and evaporation was simulated and compared with other experiments.
Lijun Wang - One of the best experts on this subject based on the ideXlab platform.
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Modeling of CuCr Contact Vacuum Arc with Different Species
2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV), 2018Co-Authors: Jie Deng, Lijun Wang, Xiao Zhang, Ze YangAbstract:This paper involves the simulation of Vacuum Arc under composite contact. A three dimensional model is developed and we consider the ionization process in the Vacuum Arc. The species transport equations, in which the fraction of each species is calculated, provides the distribution of various atoms and ions in Vacuum Arc. The model describes ions and atoms as two different processes considering that ions are influenced by self-generated magnetic field. Atoms play an inferior role in the Vacuum Arc plasma process. They gather in an `atom layer' whose thickness is a tenth of contact gap. Furthermore, the distribution of ion species is closely related to the degree of ionization. At cathode, singly charged ions are dominant. From cathode to anode, ions are ionized so that doubly particles become a major component at anode. Finally, atom calculation enables the accomplishment to combine atom with ion behavior together. Distributions of species are available by species transport equations, providing the fraction of species.
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Modeling of CuCr contact Vacuum Arc with consideration of its components
AIP Advances, 2018Co-Authors: Jie Deng, Lijun Wang, Xiao Zhang, Ze Yang, Shenli JiaAbstract:This paper involves the simulation of Vacuum Arc under composite (CuCr) contact. A three dimensional model is developed and we have considered the ionization process as well as recombination in the Vacuum Arc. The species transport equations, in which the fraction of each component is calculated, provides the distribution of various atoms and ions in Vacuum Arc. The model describes ions and atoms as two different processes considering that ions are influenced by self-generated magnetic field. Atoms play an inferior role in the process of Vacuum Arc. They gather in an ‘atom layer’ whose thickness is no more than 1mm and outside the atom layer the density of atoms declines by at most 5 orders of magnitude. The ionization process is dominated by electron temperature. The distribution of ion species is closely related to the degree of ionization. At cathode, singly charged ions are dominant. From cathode to anode, ions are ionized so that doubly charged ions become the major component at anode where singly charged ions reach their minimum density. Finally, the ionization rate is also influenced by the ionization potential of each component, so the fraction of Cr1+ is smaller than Cu1+ while Cr2+ is larger than Cu2+ in the anode center.This paper involves the simulation of Vacuum Arc under composite (CuCr) contact. A three dimensional model is developed and we have considered the ionization process as well as recombination in the Vacuum Arc. The species transport equations, in which the fraction of each component is calculated, provides the distribution of various atoms and ions in Vacuum Arc. The model describes ions and atoms as two different processes considering that ions are influenced by self-generated magnetic field. Atoms play an inferior role in the process of Vacuum Arc. They gather in an ‘atom layer’ whose thickness is no more than 1mm and outside the atom layer the density of atoms declines by at most 5 orders of magnitude. The ionization process is dominated by electron temperature. The distribution of ion species is closely related to the degree of ionization. At cathode, singly charged ions are dominant. From cathode to anode, ions are ionized so that doubly charged ions become the major component at anode where singly ch...
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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 ...
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Modeling and simulation of mixing and interaction of multi-cathode spot Vacuum Arc jets
2016 27th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV), 2016Co-Authors: Kang Qin, Lijun Wang, Jie Deng, 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 Vacuum Arc, especially the diffuse Arc. In this paper, mixing and interaction of multi-cathode spot Vacuum Arc jets were studied through simulation. To investigate the mixing and interaction of Vacuum Arc jets a steady 3D Magneto-Hydro-Dynamic (MHD) modeling was required. In order to find out the influence of different parameters on mixing and interaction of Vacuum Arc jets, models with different parameters such as currents, angel of Vacuum Arc jets, with or without electromagnetic equations and tilted jets were simulated. Six cylindrical jets were modeled to study the process of mixing and interaction of multi-cathode spot Vacuum Arc jets. Based on the simulation results, the ion number density, temperature distribution, flow velocity and ion pressure were given and analyzed.
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Vacuum Arc under axial magnetic fields: experimental and simulation reseArch
Journal of Physics D: Applied Physics, 2014Co-Authors: Shenli Jia, Zongqian Shi, Lijun WangAbstract:Axial magnetic field (AMF) technology is a most important control method of Vacuum Arc, particularly for high-current Vacuum Arcs in Vacuum interrupters. In this paper, a review of the state of current reseArch on Vacuum Arcs under AMF is presented. The major aspects of Vacuum Arc in an AMF such as Arc voltage, the motion of cathode spots, and anode activities are discussed, and the most recent progress both of experimental and simulation reseArch is presented.
E Del Bosco - One of the best experts on this subject based on the ideXlab platform.
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Plasma instability of a Vacuum Arc centrifuge.
Physical review. E Statistical nonlinear and soft matter physics, 2002Co-Authors: M J Hole, R S Dallaqua, S W Simpson, E Del BoscoAbstract:Ever since conception of the Vacuum Arc centrifuge in 1980, periodic fluctuations in the ion saturation current and floating potential have been observed in Langmuir probe measurements in the rotation region of a Vacuum Arc centrifuge. In this work we develop a linearized theoretical model to describe a range of instabilities in the Vacuum Arc centrifuge plasma column, and then test the validity of the description through comparison with experiment. We conclude that the observed instability is a "universal" instability, driven by the density gradient, in a plasma with finite conductivity.
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Radial magnetic field in Vacuum Arc centrifuges
Journal of Physics D: Applied Physics, 1997Co-Authors: R S Dallaqua, S W Simpson, E Del BoscoAbstract:According to theory, a radial component of magnetic field in the driving region of a Vacuum Arc centrifuge should increase the force and the angular velocity. Experiments with different magnetic field configurations of a Vacuum Arc centrifuge have been carried out. Langmuir probe measurements have been made as well as cross-correlation measurements of angular velocities. Based on correlation measurements, the column angular velocity increased in the presence of a radial field. This increase was accompanied by a reduction in column radius and ion density. It is concluded that Vacuum Arc centrifuge designs with a radial magnetic field component should have an improved separative performance.
Jiyan Zou - One of the best experts on this subject based on the ideXlab platform.
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ReseArch on Vacuum Arc Commutation Characteristics of a Natural-Commutate Hybrid DC Circuit Breaker
Energies, 2020Co-Authors: Dequan Wang, Minfu Liao, Xiongying Duan, Rufan Wang, Jun Qiu, Jiyan ZouAbstract:Vacuum Arc commutation is an important process in natural-commutate hybrid direct current (DC) circuit breaker (NHCB) interruption, as the duration of Vacuum Arc commutation will directly affect the Arcing time and interrupting time of NHCB. In this paper, the Vacuum Arc commutation model of NHCB was established by simplifying solid-state switch (SS) and Vacuum Arc voltage. Through theoretical analysis and experiments, the Vacuum Arc commutation characteristics of NHCB were studied. The mathematical formula of the effect of main parameters on the duration of Vacuum Arc commutation is obtained, and the changing law of the influence of the main parameters on the duration of the Vacuum Arc commutation is explored. The concept of Vacuum Arc commutation coefficient is proposed, and it is a key parameter that influences the Vacuum Arc commutation characteristics. The reseArch on the characteristics of Vacuum Arc commutation can provide theoretical foundation for the structure and parameter optimization of NHCB and other equipment that uses Vacuum Arc commutation.
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Vacuum Arc Commutation Characteristics of the DC Microgrid Hybrid Circuit Breakers
IEEE Transactions on Plasma Science, 2017Co-Authors: Minfu Liao, Guo-wei Ge, Xiongying Duan, Jinqiang Huang, Zhihui Huang, Jiyan ZouAbstract:This paper focuses on the Vacuum Arc commutation between the Vacuum Arc and the parallel-connected insulated gate bipolar transistor (IGBTs) of dc microgrid hybrid circuit breakers (HCBs). The principle of the dc HCB is analyzed and the Vacuum Arc commutation is the important process in dc HCB interruption, in which the Arcing time and the interrupting time are depended. The test circuit of the Vacuum Arc commutation is established by simplifying the parallel-connected IGBTs to an on-state resistance with large thermal capacity. The influence of the magnitude of the main current, the resistance of the IGBTs, and the externally applied transverse magnetic field (TMF) on the Vacuum Arc commutation is investigated by the electrical measure and the development of Vacuum Arc which is observed by a high-speed CMOS camera. The criteria of the Vacuum Arc commutation are obtained. The interaction between the Vacuum Arc commutation and the externally applied TMF is reseArched and the optimal magnitude of the TMF is gained. The Vacuum Arc commutation characteristics of dc HCB can be useful for parameters design and control strategy.
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Simulation reseArch of the electromagnetic characteristic of Vacuum Arc
2016 27th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV), 2016Co-Authors: Chuan Xiang, Zhihui Huang, Jiyan ZouAbstract:Vacuum Arc is the unified and balanced plasma coupled by multi-physics field, such as flow field, thermal field, electric field and magnetic field. Obviously, the electromagnetic parameters of Vacuum Arc, especially the high-current Vacuum Arc, will impact its flowing status and temperature distribution. In this paper, we studied the electromagnetic characteristic of Vacuum Arc based on an improved MHD model established in the previous reseArch work. Firstly, the spatial distribution of azimuthal magnetic field strength and electromagnetic force were calculated. Then, the influence of the electromagnetic force on the flow of Vacuum Arc was analyzed in detail. Finally, according to the numerical results, the axial current densities of Vacuum Arc with different axial magnetic field were discussed. The reseArch work contributes to optimize the external axial magnetic field to improve the breaking capacity of VCBs.
