Numerical simulation of low-current vacuum arc jet considering anode evaporation in different axial magnetic fields

As the main source of the vacuum arc plasma, cathode spots (CSs) play an important role on the behaviors of the vacuum arc. Their characteristics are affected by many factors, especially by the magnetic field. In this paper, the characteristics of the plasma jet from a single CS in vacuum arc under external axial magnetic field (AMF) are studied. A multi-species magneto-hydro-dynamic (MHD) model is established to describe the vacuum arc. The anode temperature is calculated by the anode activity model based on the energy flux obtained from the MHD model. The simulation results indicate that the external AMF has a significant effect on the characteristic of the plasma jet. When the external AMF is high enough, a bright spot appears on the anode surface. This is because with a higher AMF, the contraction of the diffused arc becomes more obvious, leading to a higher energy flux to the anode and thus a higher anode temperature. Then more secondary plasma can be generated near the anode, and the brightness of the ‘anode spot’ increases. During this process, the arc appearance gradually changes from a cone to a dumbbell shape. The appearance of the plasma jet calculated in the model is consistent with the experimental results.

Deposition of boron films using a discharge system with a hot boron anode

This work describes a discharge system for heating and evaporation of a boron powder target based on a non-self-sustained arc discharge with a filament, a hollow cathode and a hot combined anode. The measurements of the current-voltage characteristics of the discharge with a hot anode and the dependence of the anode temperature on the discharge parameters are presented. The modes of deposition of boron films have been determined.

Sensitivity improvement of solution cathode glow discharge-atomic emission spectrometry by using refrigerating anodes for optical determination of metal elements

Sensitivity and stability improvement by reducing the metal anode temperature for metal element detection using SCGD-AES.

Investigating Effects of Different Flue-Wall Deformation Modes on the Performance of Anode Baking Furnaces for Aluminum Electrolysis

In carbon anode baking furnaces, temperature and quality of carbon anodes are significantly affected by the deformation of the flue-walls, where the flue-gases flow and combustion occur. Flue-walls aging gives rise to non-homogeneous baking of the carbon anodes and results in deterioration of the anode quality, which eventually causes instabilities in aluminum reduction cells and overconsumption of anodes and energy. It is imperative to develop a fully coupled 3D multi-physics computational model which takes into account a large number of physical phenomena that play vital roles in the baking process and are affected by the flue-wall deformation mode. In the present study, the effects of flue-wall deformation modes on flue-wall cavity gas flow and anode temperature distribution are investigated. The pressure and flow distributions for different levels of flue-wall deformation are demonstrated. It is perceived that a 100 mm convex mode of flue-wall deformation leads to under-baking of anodes by almost 20 degC. For the concave mode of deformation, since the packing coke thickness reduces, overbaking of anode occurs. The methodology and results presented in the present research can be employed effectively by the aluminum industry in modifying the furnace geometrical and operational parameters to enhance baking uniformity after flue-wall is deformed.

Effect of Anode Temperature and Contact Voltage on the Design of Arc- Less Micro Electrical Contact

Objective: This paper presents the effect of anode temperature and contact voltage on the breakdown arc of micro electrical contact pair under DC excitation. Methods: A rectangular micro electrical contact pair is considered. The resistance and capacitance of the contact pair are obtained for the materials Al, Cu, Au and Pt. The anode temperature is calculated based on the 3D heat equation. Pre-breakdown arc due to anode temperature is analyzed. Result: The breakdown voltage and breakdown electric field characteristics for the gap between 0.5µm and 30µm are reported. The electric field of micro electrical contact pair is analyzed mathematically. The calculated values of resistance, anode temperature and electric field are compared with the simulation results obtained using COMSOL multiphysics FEA software tool. The arc-less operating region of micro contact is identified. Four cases with the ratings 50V/5A, 50V/0.5A, 400 V/ 5A and 400V/0.5A have been considered for the analysis of arcless micro electrical contact. Conclusion: These results can be considered while designing arc-less micro electrical switches, micro relays and micro circuit breakers which can be applicable for the future DC electric power distribution, protection system and automobiles. Also these results can be considered when designing micro actuators, sensors and electrostatic devices.