ICCD Imaging of Coexisting Arc Roots and Arc Column in a Large-Area Dispersed Arc-Plasma Source

Zhang

et al. 2015

Chinese Phys. B

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 mm 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.

Section: Experimental Apparatusmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evolution of magnetically rotating arc into large area arc plasma

Zhang

et al. 2015

Chinese Phys. B

“…It is well known that arcs can be attached to the anode with diffusive and constricted modes [2][3][4][5][6][7][8][9][10][11][12], as shown in figure 1. When the cathode jet is strong and dominant, the arc attaches to the anode with a diffusive mode.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of constricted and diffusive arc–anode attachments in wall-stabilized transferred argon arcs

Zhu

Sun

et al. 2019

Plasma Sci. Technol.

A numerical simulation is conducted to investigate arc-anode attachment behavior, especially the formation mechanism of the constricted arc attachment mode for the water-cooled anode of wall-stabilized transferred argon arcs. Argon molecular ions and the corresponding kinetic processes are included to the finite-rate chemistry model in order to capture the chemical nonequilibrium characteristics of the arc near the anode region. Modeling results show that constricted and diffusive arc-anode attachments can be self-consistently obtained at different arc currents while keeping other parameters unchanged. The dominant kinetic processes contributing to ionization and recombination in the arc center and fringes are presented. The results show that in arc fringes and the arc attachment region, molecular ion recombination plays an important role which leads to the rapid loss of electrons. The radial evolution of the production, loss and transport processes of electrons is further analyzed. It is found that for the constricted arc attachment mode, both the recombination and convection transport caused by the anode jet result in the loss of electrons at the arc fringes, which leads to the shrinkage of the arc column at the anode. The formation of the anode jet is due to the combined action of radial and axial Lorentz forces in the anode region.

Observation of arc modes in a magnetically rotating arc plasma generator

Cui

Zhang

et al. 2017

Contrib. Plasma Phys

An arc plasma can present various forms under the influence of an external magnetic field. In this study, a magnetically rotating arc plasma generator has been developed to produce three arc modes, namely rigid arc, distorted arc, and diffuse arc, which are obtained by controlling the gas flow rate. The evolution of these arc modes are experimentally studied and discussed. Results show that, as the gas flow rate increases, the arc mode is first transformed from the rigid to the distorted mode, and then to the diffuse mode. Comparisons show that the location of the arc attachment is a key factor in determining the rigid and distorted modes. The diffuse arc is observed under larger gas flow rates, but the completely diffuse arc can exist only within a narrow range of gas flow rates. Compared to the distorted arc, the diffuse arc has not only better stability but also a wider high-temperature plasma zone, which indicates that the diffuse mode may be more useful in industry. KEYWORDSarc attachment, arc mode, arc voltage, magnetically rotating arc plasma 1