scholarly journals Increasing prediction accuracy of plasma arc properties by considering current density deduced from measured cathode region

AIP Advances ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 085211
Author(s):  
Hao Tang ◽  
ZuMing Liu
Keyword(s):  
Current Density ◽  
Prediction Accuracy ◽  
Cathode Region ◽  
Plasma Arc

Improving the Prediction Accuracy of Keyhole Establishment Time in Plasma Arc Welding

2014 ◽  
Vol 66 (4) ◽  
pp. 420-432 ◽  
Author(s):  
C. S. Wu ◽  
W. Zheng ◽  
M. A. Chen
Keyword(s):  
Arc Welding ◽  
Prediction Accuracy ◽  
Plasma Arc Welding ◽  
Plasma Arc

Runaway electrons and current density in the cathode region of a vacuum arc

1989 ◽  
Vol 22 (2) ◽  
pp. 368-370 ◽  
Author(s):  
B E Djakov
Keyword(s):  
Current Density ◽  
Cathode Region ◽  
Vacuum Arc ◽  
Runaway Electrons

Effect of ultrasonic vibration on current density and keyholing capability of plasma arc

2020 ◽  
Vol 25 (5) ◽  
pp. 422-430 ◽  
Author(s):  
Cheng Zhang ◽  
ChuanSong Wu ◽  
Shuoshuo Tian
Keyword(s):  
Ultrasonic Vibration ◽  
Current Density ◽  
Plasma Arc

Modeling Three-Dimensional Plasma Arc in Gas Tungsten Arc Welding

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
G. Xu ◽  
J. Hu ◽  
H. L. Tsai
Keyword(s):  
Magnetic Field ◽  
Weld Pool ◽  
Current Density ◽  
Arc Welding ◽  
Three Dimensional ◽  
Gas Tungsten Arc Welding ◽  
Plasma Arc ◽  
Gas Tungsten Arc ◽  
Pool Model ◽  
Gas Tungsten

This article presents a three-dimensional (3D) mathematical model for the plasma arc in gas tungsten arc welding (GTAW). The velocity, pressure, temperature, electric potential, current density, and magnetic field of the plasma arc are calculated by solving the mass, momentum, and energy conservation equations coupled with electromagnetic equations. The predicted results were compared with the published experimental data and good agreements were achieved. This 3D model can be used to study a nonaxisymmetric arc that may be caused by the presence of nonaxisymmetric weld pools, joint configurations, and perturbations such as an external magnetic field. This study also provides a method to calculate 3D arc pressure, heat flux, and current density on the surface of the weld pool which, if coupled with a weld pool model, will become a complete model of GTAW.

scholarly journals Effect of a DC Stray Current on the Corrosion of X80 Pipeline Steel and the Cathodic Disbondment Behavior of the Protective 3PE Coating in 3.5% NaCl Solution

Coatings ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 29 ◽  
Author(s):  
Xinhua Wang ◽  
Zuquan Wang ◽  
Yingchun Chen ◽  
Xuting Song ◽  
Yong Yang
Keyword(s):  
Direct Current ◽  
Current Density ◽  
Pipeline Steel ◽  
Three Dimensional ◽  
Steel Corrosion ◽  
Cathode Region ◽  
Nacl Solution ◽  
Stray Current ◽  
X80 Pipeline Steel ◽  
X80 Steel

The influence of a direct current (DC) stray current on the corrosion and cathodic disbondment of X80 steel coated with a polyethylene (3PE) coating in 3.5% NaCl solution was studied by immersion experiments, electrochemical tests, three-dimensional microscopy, and a surface analysis. The results showed that the potential of the X80 steel sample shifts under the direct current. After 100A/m2 DC interference was applied, the potential of the sample in the anode region positively shifted from –0.68 to –0.43 V. At the same time, the sample in the cathode region negatively shifted to –1.45 V. Under the DC anode action, the X80 steel corrosion exhibited no passivation and followed Faraday’s law of electrolysis, in which the corrosion rate is proportional to the current density. Three-dimensional (3D) digital microscopy showed that, as the DC current increased, the depth of the corrosion pit also increased (gradually), indicating a higher corrosion degree. The sample in the cathode region only underwent a hydrogen evolution reaction, which caused cathodic disbondment of the coating. The stray current had a critical current density for the coating disbonding: the coating delamination area reached its maximum and then remained unchanged.

Velocity and Current Density Evaluation of Combined Plasma Arc for High Temperature Materials Processing by Computational Simulation

2011 ◽  
Vol 314-316 ◽  
pp. 728-732
Author(s):  
Xiao Juan Dong ◽  
Jian Bing Meng ◽  
Zhan Min Yin ◽  
Chang Ning Ma
Keyword(s):  
Flow Rate ◽  
Current Density ◽  
Gas Flow ◽  
Computational Simulation ◽  
Current Density Distribution ◽  
Axial Direction ◽  
Plasma Arc ◽  
Nozzle Outlet ◽  
Flow Phenomena ◽  
Specific Calculations

A mathematical model was established to describe the electromagnetic, heat flow and fluid flow phenomena within a combined plasma arc. In the development of the model allowance was made for the conservation of mass, momentum, energy and the Maxwell equations. With the ANSYS finite analysis software, specific calculations were presented for a pure argon system, operating in a laminar mode. The distributions of the current density and velocity of combined plasma arc were gotten. In addition, the influences of process parameters, including arc current, argon gas flow rate and the distance from the nozzle outlet to the anode workpiece, on the velocity along the axial direction and current density distribution along radial direction were evaluated, respectively. The results shows that the velocity and current density of combined plasma arc are much dependent on the working current, while are less sensitive to the argon flow rate and the distance from the nozzle outlet to the workpiece anode.

Voltage-current density characteristics of noble gas mixture discharges in the cathode region

1991 ◽  
Vol 24 (8) ◽  
pp. 1322-1327 ◽  
Author(s):  
Z Donko ◽  
K Rozsa ◽  
M Janossy
Keyword(s):  
Current Density ◽  
Noble Gas ◽  
Cathode Region ◽  
Gas Mixture

Activated Prominences; Mechanisms for Activation and Eruption

1979 ◽  
Vol 44 ◽  
pp. 307-313
Author(s):  
D.S. Spicer
Keyword(s):  
Pressure Gradient ◽  
Density Gradient ◽  
Current Density ◽  
Convective Instability ◽  
Tearing Mode ◽  
Magnetic Shear ◽  
Long Wavelength ◽  
Ideal Mhd ◽  
Gradient Change ◽  
Accelerated Particles

A possible relationship between the hot prominence transition sheath, increased internal turbulent and/or helical motion prior to prominence eruption and the prominence eruption (“disparition brusque”) is discussed. The associated darkening of the filament or brightening of the prominence is interpreted as a change in the prominence’s internal pressure gradient which, if of the correct sign, can lead to short wavelength turbulent convection within the prominence. Associated with such a pressure gradient change may be the alteration of the current density gradient within the prominence. Such a change in the current density gradient may also be due to the relative motion of the neighbouring plages thereby increasing the magnetic shear within the prominence, i.e., steepening the current density gradient. Depending on the magnitude of the current density gradient, i.e., magnetic shear, disruption of the prominence can occur by either a long wavelength ideal MHD helical (“kink”) convective instability and/or a long wavelength resistive helical (“kink”) convective instability (tearing mode). The long wavelength ideal MHD helical instability will lead to helical rotation and thus unwinding due to diamagnetic effects and plasma ejections due to convection. The long wavelength resistive helical instability will lead to both unwinding and plasma ejections, but also to accelerated plasma flow, long wavelength magnetic field filamentation, accelerated particles and long wavelength heating internal to the prominence.

Microstructural characterization of YBa2Cu3O7-x thin films formed by metalorganic CVD

1991 ◽  
Vol 49 ◽  
pp. 1080-1081
Author(s):  
P. Lu ◽  
W. Huang ◽  
C.S. Chern ◽  
Y.Q. Li ◽  
J. Zhao ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Film Growth ◽  
Chemical Vapor ◽  
Microstructural Characterization ◽  
Ion Milling ◽  
Conventional Grinding

The YBa2Cu3O7-x thin films formed by metalorganic chemical vapor deposition(MOCVD) have been reported to have excellent superconducting properties including a sharp zero resistance transition temperature (Tc) of 89 K and a high critical current density of 2.3x106 A/cm2 or higher. The origin of the high critical current in the thin film compared to bulk materials is attributed to its structural properties such as orientation, grain boundaries and defects on the scale of the coherent length. In this report, we present microstructural aspects of the thin films deposited on the (100) LaAlO3 substrate, which process the highest critical current density.Details of the thin film growth process have been reported elsewhere. The thin films were examined in both planar and cross-section view by electron microscopy. TEM sample preparation was carried out using conventional grinding, dimpling and ion milling techniques. Special care was taken to avoid exposure of the thin films to water during the preparation processes.

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