The recovery of electric strength of an arc-discharge column following rapid interruption of the current

Mathematical model of appearance and progress of noise characteristics in super-power electric arc steel furnaces is considered in the paper. It is shown that noise generation is coupled with pulsations of axial plasma flows in arc discharge caused by fluctuations of electrodynamic pressure on discharge column formed by interaction between its own magnetic field and current flowing in the arc. Simulation results have shown that pressure in arc axis alternates at frequency 100 Hz with amplitude 6600 N/m2 for arc current 80 kA. Basic frequencies of arc noise are aliquot to 100 Hz, that fact is verified by exploitation practice of arc steel furnaces. Sound intensity level in workspace riches 160 dB, but thanks to shielding by case and fused metal and slag it falls to 115–120 dB on service area of furnace. It has shown that maximal amplitudes in frequency spectrum of the noise are in range 5–150 Hz. Generated noise amplitudes and frequency ranges depend on arc discharges' resistance, which are defined by ionization level of gases. According to Saha equation, iron vapor is ionized by 70 %, calcium vapor – by 95 %, and ionization level of air is no more than 1.5 %. It has been experimentally shown that in melting of stock coated with lime noise intensity is decreased by 6–8 % against no-lime iron melting because of lower calcium ionization potential (6.11 eV). It has been ascertained that for long arc with high voltages the sound intensity is decreased by 3–4 % as compared with short arc of the same current. It has shown that suppression of low-frequency components of noise energy is possible by optimization of electromechanical oscillations of electrodes, electrode-holders and cable strips, additionally to inclusion lime in stock mixture. The appropriateness of improvement electric arc furnaces hermeticity and development of the furnaces for operation with lowered currents and enlarged transformers' voltages have been approved.

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Free double layers in mercury-arc discharges

Journal of Plasma Physics ◽

10.1017/s0022377800014380 ◽

1989 ◽

Vol 42 (2) ◽

pp. 321-352 ◽

Cited By ~ 16

Author(s):

Homero Santiago Maciel ◽

J. E. Allen

Keyword(s):

Double Layer ◽

Discharge Current ◽

Arc Discharge ◽

Electrical Energy ◽

High Energy ◽

Double Layers ◽

Electrostatic Energy ◽

High Current ◽

Discharge Column ◽

Current Limitation

A study has been carried out of free double layers formed within the plasma volume of a low-pressure mercury-arc discharge at high current densities. The free double layer is observed to form as a visible boundary, which drifts slowly from the central section of the discharge. Current-driven instabilities are observed as the discharge current is gradually increased to a critical value, at which current limitation is observed to occur. This process, which is accompanied by high-current spikes, ceases when the free double layer becomes visible as a sharp boundary dividing the discharge column into two regions of different luminosities. The layer is observed to form in the later stages of current limitation, the onset of which occurs for a ratio of drift to thermal speed of electrons of about unity. Electrical energy is converted by the layer into kinetic energy of the charged particles. Accordingly, high-energy ions were measured by means of an electrostatic energy analyser. The multiple-sheath character of the free ‘double layer’, which is inferred from probe measurements of potential profiles, is discussed and comparisons with other space-charge structures with the same topology are made.

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Effect of the Column Structure of the Arc Discharge in Vacuum on the Energy Efficiency of the Welding Process

Proceedings of Higher Educational Institutions Маchine Building ◽

10.18698/0536-1044-2021-2-18-25 ◽

2021 ◽

pp. 18-25

Author(s):

V.M. Nerovnyy

Keyword(s):

Energy Efficiency ◽

Hollow Cathode ◽

Arc Discharge ◽

Welding Process ◽

Energy Concentration ◽

Physical Processes ◽

Cathode Plasma ◽

Discharge Column ◽

Wide Range ◽

Local Parameters

An arc discharge with a hollow cathode in vacuum has two forms of steady state: diffuse ("blurred" external column) and constricted (a visible cylindrical column providing a high directivity of the discharge energy transfer with minimal scattering in the radial direction). The article considers the dependence of the energy concentration in the heating spot and, consequently, the energy efficiency of the welding process on the structure of the arc discharge column with a hollow cathode when changing its mode parameters. The distributions of local parameters of the arc discharge with hollow cathode plasma are shown in a wide range of its modes based on probe studies. Considering the distributions allows obtaining a fairly complete picture of the physical processes in the plasma of the external discharge column and the effect of its structure on the energy efficiency of the welding process. It is shown that an arc discharge with a hollow cathode in a vacuum, the outer column of which has the structure of a plasma beam, is a relatively highly concentrated energy source and in terms of specific energy indicators can reach an energy concentration second only to beam energy sources.

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Measuring electric field strength in an arc-discharge column

Journal of Applied Spectroscopy ◽

10.1007/bf00604518 ◽

1973 ◽

Vol 18 (4) ◽

pp. 535-537

Author(s):

V. N. Apolitskii ◽

N. S. Arsent'ev ◽

A. G. Nikolaev

Keyword(s):

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Arc Discharge ◽

Discharge Column

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Preparation and characterization of thin films of carbon nitride

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100136891 ◽

1995 ◽

Vol 53 ◽

pp. 104-105

Author(s):

L. Wan ◽

R. F. Egerton

Keyword(s):

Carbon Nitride ◽

Arc Discharge ◽

Ion Beam ◽

Chemical Vapor ◽

Reactive Sputtering ◽

Vacuum Arc ◽

Specimen Preparation ◽

Bonding Structure ◽

Electron Energy Loss

INTRODUCTION Recently, a new compound carbon nitride (CNx) has captured the attention of materials scientists, resulting from the prediction of a metastable crystal structure β-C3N4. Calculations showed that the mechanical properties of β-C3N4 are close to those of diamond. Various methods, including high pressure synthesis, ion beam deposition, chemical vapor deposition, plasma enhanced evaporation, and reactive sputtering, have been used in an attempt to make this compound. In this paper, we present the results of electron energy loss spectroscopy (EELS) analysis of composition and bonding structure of CNX films deposited by two different methods.SPECIMEN PREPARATION Specimens were prepared by arc-discharge evaporation and reactive sputtering. The apparatus for evaporation is similar to the traditional setup of vacuum arc-discharge evaporation, but working in a 0.05 torr ambient of nitrogen or ammonia. A bias was applied between the carbon source and the substrate in order to generate more ions and electrons and change their energy. During deposition, this bias causes a secondary discharge between the source and the substrate.

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