One of the issues of plasma technologies is the design of a high-performance plasma source.Due to its properties,a diffuse vacuum arc discharge may be one of the promising options.In this study,the dependence of the c...One of the issues of plasma technologies is the design of a high-performance plasma source.Due to its properties,a diffuse vacuum arc discharge may be one of the promising options.In this study,the dependence of the charge composition of a diffuse vacuum arc plasma with a hot cathode on the value of the external axial magnetic field and discharge voltage was investigated.The study was conducted with a thermionic gadolinium(Gd)cathode.Monitoring the charge composition was done by analyzing the emission spectra of the plasma.Steady states of arc discharge were obtained for a range of parameters.The arc currents were 30 and 40 A,the arc voltage was up to 29 V and the external magnetic field was varied from 0 to 20 mT.It was found that in the presence of the eternal magnetic field the defining factor of the charge composition was the arc voltage.Moreover,for a fixed arc voltage,an increase in magnitude causes an increase in intensities of all atomic and ionic plasma components(Gd,Gd+,Gd++).The potential causes of this effect were discussed.It was established that in an axial magnetic field it is possible to implement discharge modes with predominance of single-charge ions by increasing the magnitude of the external magnetic field.Potentially,these discharge modes will be of use for the implementation of plasma methods for reprocessing spent nuclear fuel.展开更多
An arc channel tends to shrink due to its conductivity increasing with the increase of temperature. In this study, to generate large area arc plasma, we construct a magnetically rotating arc plasma generator, which ma...An arc channel tends to shrink due to its conductivity increasing with the increase of temperature. In this study, to generate large area arc plasma, we construct a magnetically rotating arc plasma generator, which mainly consists of a lanthanide tungsten cathode （13 mm in diameter）, a concentric cylindrical graphite anode chamber （60 nun in diameter） and a solenoid coil for producing an axial magnet field. By controlling the cold gas flow, the magnetically rotating arc evolves from constricted mode to diffuse mode, which almost fills the whole arc chamber cross section. Results show that the diffuse arc plasma has better uniformity and stability. The formation mechanism of large area arc plasma is discussed in this paper.展开更多
Magnetically dispersed arc plasma exhibits typically dispersed uniform arc column as well as diffusive cathode root and diffusive anode root. In this paper magnetically dispersed arc plasma coupled with solid cathod...Magnetically dispersed arc plasma exhibits typically dispersed uniform arc column as well as diffusive cathode root and diffusive anode root. In this paper magnetically dispersed arc plasma coupled with solid cathode is numerically simulated by the simplified cathode sheath model of LOWKE . The numerical simulation results in argon show that the maximum value of arc root current density on the cathode surface is 3.5×10^7 A/m^2）, and the maximum value of energy flux on the cathode surface is 3× 10^7 J/m^2, both values are less than the average values of a contracted arc, respectively.展开更多
An arc channel at atmospheric pressure tends to shrink generally. In this paper, a non-transferred DC arc plasma device with multiple cathode is introduced to produce a large area arc plasma at atmospheric pressure. T...An arc channel at atmospheric pressure tends to shrink generally. In this paper, a non-transferred DC arc plasma device with multiple cathode is introduced to produce a large area arc plasma at atmospheric pressure. This device is comprised of a 42-mm diameter tubular chamber, multiple cathode which is radially inserted into the chamber, and a tungsten anode with a nozzle in its center. In argon/helium atmosphere, a large area and circumferential homogenous diffuse arc plasma, which fills the entire cross section surrounded by the cathode tips, is observed. Results show that the uniformity and stability of diffuse arc plasma are strongly related to the plasma forming gas. Based on these experimental results, an explanation to the arc diffusion is suggested. Moreover, the electron excitation temperature and electron density measured in diffuse helium plasma are much lower than those of constricted arc column, which indicates the diffuse helium plasma probably deviates from the local thermodynamic equilibrium state. Unlike the common non-transferred arc plasma devices, this device can provide a condition for axial-fed feedstock particles. The plasma device is attempted to spheroidize alumina powders by using the central axis to send the powder. Results show that the powder produced is usually a typical hollow sphere.展开更多
For realizing diffused anode attachment in pure nitrogen arcs, a special arc plasma generator was designed and combined with suitable working parameters such as gas flow rate and arc current. The anode has a flow-rest...For realizing diffused anode attachment in pure nitrogen arcs, a special arc plasma generator was designed and combined with suitable working parameters such as gas flow rate and arc current. The anode has a flow-restrictor channel of 2.8 mm diameter and downstream expansion half-angle of 8°, with the purpose of creating a dispersed nitrogen-arc column by strong gasdynamic expansion effect. Results show that, when thermal blocking condition existed in the flow restrictor and the cathode cavity pressure was higher than that in the exit chamber by at least 9 kPa, the action due to gasdynamic expansion could be much stronger than the self-magnetic contraction effect of the arc and the nitrogen arc column could be effectively dispersed to form a sufficiently diffused attachment on the water-cooled anode surface.展开更多
基金supported by the Russian Science Foundation(No.23-72-10073)。
文摘One of the issues of plasma technologies is the design of a high-performance plasma source.Due to its properties,a diffuse vacuum arc discharge may be one of the promising options.In this study,the dependence of the charge composition of a diffuse vacuum arc plasma with a hot cathode on the value of the external axial magnetic field and discharge voltage was investigated.The study was conducted with a thermionic gadolinium(Gd)cathode.Monitoring the charge composition was done by analyzing the emission spectra of the plasma.Steady states of arc discharge were obtained for a range of parameters.The arc currents were 30 and 40 A,the arc voltage was up to 29 V and the external magnetic field was varied from 0 to 20 mT.It was found that in the presence of the eternal magnetic field the defining factor of the charge composition was the arc voltage.Moreover,for a fixed arc voltage,an increase in magnitude causes an increase in intensities of all atomic and ionic plasma components(Gd,Gd+,Gd++).The potential causes of this effect were discussed.It was established that in an axial magnetic field it is possible to implement discharge modes with predominance of single-charge ions by increasing the magnitude of the external magnetic field.Potentially,these discharge modes will be of use for the implementation of plasma methods for reprocessing spent nuclear fuel.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11035005,11475174,and 50876101)the Science Instrument Foundation of the Chinese Academy of Sciences(Grant No.Y201162)
文摘An arc channel tends to shrink due to its conductivity increasing with the increase of temperature. In this study, to generate large area arc plasma, we construct a magnetically rotating arc plasma generator, which mainly consists of a lanthanide tungsten cathode （13 mm in diameter）, a concentric cylindrical graphite anode chamber （60 nun in diameter） and a solenoid coil for producing an axial magnet field. By controlling the cold gas flow, the magnetically rotating arc evolves from constricted mode to diffuse mode, which almost fills the whole arc chamber cross section. Results show that the diffuse arc plasma has better uniformity and stability. The formation mechanism of large area arc plasma is discussed in this paper.
基金supported by National Natural Science Foundation of China (Nos.50876101,11035005)
文摘Magnetically dispersed arc plasma exhibits typically dispersed uniform arc column as well as diffusive cathode root and diffusive anode root. In this paper magnetically dispersed arc plasma coupled with solid cathode is numerically simulated by the simplified cathode sheath model of LOWKE . The numerical simulation results in argon show that the maximum value of arc root current density on the cathode surface is 3.5×10^7 A/m^2）, and the maximum value of energy flux on the cathode surface is 3× 10^7 J/m^2, both values are less than the average values of a contracted arc, respectively.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11475174 and11035005)the Fundamental Research Funds for the Central Universities,China(Grant No.WK2090130021)
文摘An arc channel at atmospheric pressure tends to shrink generally. In this paper, a non-transferred DC arc plasma device with multiple cathode is introduced to produce a large area arc plasma at atmospheric pressure. This device is comprised of a 42-mm diameter tubular chamber, multiple cathode which is radially inserted into the chamber, and a tungsten anode with a nozzle in its center. In argon/helium atmosphere, a large area and circumferential homogenous diffuse arc plasma, which fills the entire cross section surrounded by the cathode tips, is observed. Results show that the uniformity and stability of diffuse arc plasma are strongly related to the plasma forming gas. Based on these experimental results, an explanation to the arc diffusion is suggested. Moreover, the electron excitation temperature and electron density measured in diffuse helium plasma are much lower than those of constricted arc column, which indicates the diffuse helium plasma probably deviates from the local thermodynamic equilibrium state. Unlike the common non-transferred arc plasma devices, this device can provide a condition for axial-fed feedstock particles. The plasma device is attempted to spheroidize alumina powders by using the central axis to send the powder. Results show that the powder produced is usually a typical hollow sphere.
基金supported by the National Natural Science Foundation of China (11575273)
文摘For realizing diffused anode attachment in pure nitrogen arcs, a special arc plasma generator was designed and combined with suitable working parameters such as gas flow rate and arc current. The anode has a flow-restrictor channel of 2.8 mm diameter and downstream expansion half-angle of 8°, with the purpose of creating a dispersed nitrogen-arc column by strong gasdynamic expansion effect. Results show that, when thermal blocking condition existed in the flow restrictor and the cathode cavity pressure was higher than that in the exit chamber by at least 9 kPa, the action due to gasdynamic expansion could be much stronger than the self-magnetic contraction effect of the arc and the nitrogen arc column could be effectively dispersed to form a sufficiently diffused attachment on the water-cooled anode surface.
