scholarly journals On hybrid type of cathode attachment in high current vacuum arcs

2021 ◽  
Vol 2064 (1) ◽  
pp. 012030
Author(s):  
D L Shmelev ◽  
S A Chaikovsky ◽  
I V Uimanov
Keyword(s):  
Plasma Flow ◽  
Plasma Jet ◽  
Cathode Current Density ◽  
Time Instant ◽  
Plasma Jets ◽  
High Current ◽  
Linear Mass ◽  
Plasma Gun ◽  
Supersonic Plasma ◽  
Cathode Current

Abstract This paper discusses the issues of a possible change of the type of cathode attachment of high-current vacuum arcs (HCVA) with an average cathode current density of more than 105 A/cm2. This type of HCVA is used as pumping plasma gun in experiments with plasma puff z-pinches. These experiments showed that the measured linear mass of the HCVA plasma jet is much higher (by a factor of 10 or more) than the expected mass, which can be obtained from the assumption that cathode attachment occurs only through a multitude of cathode spots emitting supersonic plasma jets. It is shown that in HCVA of the type under consideration, at some time instant there are two types of cathode attachments - cathode spots and thermionic erosion attachment (TEA). It can be said that HCVA of this type have a hybrid cathodic attachment. Unlike cathode spots, TEA produces a subsonic plasma flow, which contributes to an increase in the linear mass of the HCVA plasma jet.

scholarly journals Determination of the voltage drop on a high-current vacuum arc discharge under conditions of a limited cross-section of the plasma flow

2021 ◽  
Vol 2064 (1) ◽  
pp. 012019
Author(s):  
A G Rousskikh ◽  
A S Zhigalin ◽  
V I Oreshkin ◽  
P Artyomov
Keyword(s):  
Cross Section ◽  
Plasma Flow ◽  
Voltage Drop ◽  
Arc Discharge ◽  
Vacuum Arc ◽  
High Current ◽  
Plasma Gun ◽  
Flow Through ◽  
Arc Current

Abstract The work is devoted to the study of the high-current vacuum arc discharge characteristics under conditions of a limited cross-section of the plasma flow. The experiments were carried out on the IMRI-5 setup with a sinusoidal arc current amplitude of 300–350 kA and a rise time of 500 ns. Aluminum rods with diameters from 3 to 7 mm were used as a cathode. The plasma flow was formed in a channel whose diameter was equal to that of the cathode. The features of the formation of a plasma jet with various configurations of the used plasma gun are described. The electrophysical parameters of the arc discharge are presented. Theoretical estimates of the voltage drop across the high-current arc during the outflow of a plasma flow through holes with a limited diameter are provided.

SEM and EDS study of magnetic effects on electroplating of Cr-Fe alloys

1984 ◽  
Vol 42 ◽  
pp. 502-503
Author(s):  
C.A. Cousins ◽  
J. Dash
Keyword(s):  
Current Efficiency ◽  
Cathode Current Density ◽  
High Current ◽  
Cell Temperature ◽  
Horizontal Magnetic Field ◽  
High Current Efficiency ◽  
Initial Cell ◽  
Electrolytic Cells ◽  
Cathode Current ◽  
Fe Alloys

Some preliminary results of the effects of magnetic fields on high current efficiency electrodeposition of CR-FE alloys were reported previously (1). For the present experiments, high purity Ni cathodes and Pb anodes were used. The cathode current density was 0.25 amps/cm2 and the cathode and anode were positioned vertically and parallel to each other and to the horizontal magnetic field (B). Two series-wired water-jacketed electrolytic cells were used. One cell was located between the pole pieces of an electromagnet and the other was approximately 30 cm away. The plating time was 30 minutes for each experiment and the current efficiency varied from 51.8 to 53.9% for the deposits in Fig. A. The initial cell temperature was 40°C.

Material Processing Using Supersonic Reactive Plasma Jets in Thermodynamical and Chemical Nonequilibrium State

2005 ◽  
Vol 502 ◽  
pp. 303-308
Author(s):  
Hirokazu Tahara ◽  
Kenji Fujiuchi ◽  
Yasutaka Ando
Keyword(s):  
Material Processing ◽  
Plasma Flow ◽  
Plasma Jet ◽  
Nonequilibrium State ◽  
Plasma Jets ◽  
Excitation Temperature ◽  
Rotational Excitation ◽  
Chemical Nonequilibrium ◽  
Ceramic Particles ◽  
Reactive Plasma

Nitriding of metals and reactive spraying for nitride ceramics are planned using a 10-kW-class direct-current nitrogen or H2/N2-mixture arc plasma jet generator with a supersonic expansion nozzle in a low pressure environment. The H-atom electronic excitation temperature and the N2 molecule-rotational excitation temperature intensively decreased downstream in the nozzle although the NH molecule-rotational excitation temperature did not show an axial decrease. As approaching the titanium plate for nitriding, the thermodynamical nonequilibrium plasma came to be a temperature-equilibrium one. Both the electron number density near the plate and the heat flux into the plate increased with H2 mole fraction for mixtures gases. In cases with H2/N2-mixtures, a radical of NH with a radially wide distribution is considered to contribute to the better nitriding as a chemically active and non heating process. Numerical simulation was carried out to examine interactions between injected ceramic particles and the nitrogen plasma flow. When plasma was accelerated to supersonic flow through the nozzle, ceramic particles were smoothly accelerated by the aerodynamic drag force and heated in the highly-reactive plasma flow. The calculated results showed that the supersonic plasma jet in thermodynamical and chemical nonequilibrium state might have some potentials for material processing, even for spraying, because of its high reactivity.

Bituminous Insulations Durability of Underground Metallic Pipelines I Field investigations

2017 ◽  
Vol 68 (3) ◽  
pp. 581-585 ◽  
Author(s):  
Gabriela Oprina ◽  
Ladislau Radermacher ◽  
Daniel Lingvay ◽  
Dorian Marin ◽  
Andreea Voina ◽  
...  
Keyword(s):  
Cathode Current Density ◽  
Induced Voltage ◽  
Cathodic Current ◽  
Field Investigations ◽  
Operation Period ◽  
Cathode Current ◽  
Protection Potential ◽  
Cathodic Protection System ◽  
Corrosion State ◽  
Good Agreement

The corrosion state of an underground metallic pipeline of �161 mm and 565 m length was assessed by specific electrical and electrochemical measurements. The investigated pipe, buried in 1997, was protected against corrosion by successive layers of bituminous material with a total thickness of 1 to 1.2 mm. The pipeline crosses three electrified railway lines (50 Hz - 28 kV), and then its route is approximately parallel to these lines; thus, the induced AC voltages between line and ground were calculated obtaining values between 4.05 and 7.1 Vrms, in good agreement with the values measured in the accessible points. The measurements regarding the insulation capacity against corrosion of the bituminous insulation, performed at one month and after 19 years of burial, showed an increase of the average cathode current density needed for obtaining the protection potential in the range �1.00 � �1.28 VCu/CuSO4 of approx. three times (from 6.65 up to 19.96 mA/m2), in good agreement with the evolution of the insulation resistance measured between the steel pipe (having a contact area with the ground of 270.5 m2) and a ground socket of 4 W, which decreased from 995 to 315 kW. Following the analysis and processing of the field collected data, it is considered that, by implementing a cheap cathodic protection system (without cathodic current power supply), based on the rectification of the AC induced voltage, the safe operation period of the investigated pipeline may be extended by at least 50 years.

RESTORATION OF MACHINE PARTS WITH GALVANIZED ZINC COATINGS

2020 ◽  
Vol 4 (141) ◽  
pp. 140-147
Author(s):  
MIKHAIL VIKHAREV ◽  
◽  
VLADIMIR YUDIN ◽  
VESELOVSKIY NIKOLAY ◽  
◽  
...  
Keyword(s):  
Current Density ◽  
Cathode Surface ◽  
Zinc Coating ◽  
Cathode Current Density ◽  
Research Purpose ◽  
Cathode Layer ◽  
Properties Of Coatings ◽  
Chemical Polarization ◽  
Cathode Current ◽  
Zinc Coatings

The article shows the role of electroplating in the restoration of parts, indicates the advantages of restoring parts with electroplating over other methods, and gives the characteristics and properties of coatings obtained by electroplating. (Research purpose) The research purpose is in increasing the speed of application of zinc electroplating when restoring parts. (Materials and methods) The cathode current density has a decisive influence on the coating speed. The main reason for limiting the cathode current density during galvanizing from sulfuric acid electrolytes is the chemical polarization of the cathode. The article presents a study on the designed installation for the application of galvanic coatings. When applying coatings to the internal surfaces of parts, there was used a device with activating elements having an electromechanical rotation drive. This device prevents depletion of the near-cathode layer of the electrolyte and reduces the chemical polarization of the cathode. Elements made of moisture-resistant skin were used as activators. (Results and discussion) The article presents the results of experiments as a dependence of the coating speed on the speed of the activator relative to the restoring surface. It also presents the relationship between the size of the abrasive grains of the activating elements, the force of their pressing against the cathode surface, the speed of movement of the activator and the speed of applying the zinc coating, as well as its quality. By activating the cathode surface, it was possible to raise the operating current density to 100-150 amperes per square decimeter. The speed of application of zinc coatings is 16-25 micrometers per minute. (Conclusions) In the course of research, authors determined the conditions of electrolysis during galvanizing, which provide a significant increase in the cathode current density and the rate of application of these coatings during the restoration of parts.

scholarly journals High-Speed Video Analysis of the Process Stability in Plasma Spraying

2021 ◽  
Author(s):  
K. Bobzin ◽  
M. Öte ◽  
M. A. Knoch ◽  
I. Alkhasli ◽  
H. Heinemann
Keyword(s):  
Plasma Spraying ◽  
High Speed ◽  
Plasma Jet ◽  
Plasma Jets ◽  
Time Dependent ◽  
Acquisition Time ◽  
Fast Fourier Transformation ◽  
Frequency Spectra ◽  
Dependent Signal ◽  
The Stability

AbstractIn plasma spraying, instabilities and fluctuations of the plasma jet have a significant influence on the particle in-flight temperatures and velocities, thus affecting the coating properties. This work introduces a new method to analyze the stability of plasma jets using high-speed videography. An approach is presented, which digitally examines the images to determine the size of the plasma jet core. By correlating this jet size with the acquisition time, a time-dependent signal of the plasma jet size is generated. In order to evaluate the stability of the plasma jet, this signal is analyzed by calculating its coefficient of variation cv. The method is validated by measuring the known difference in stability between a single-cathode and a cascaded multi-cathode plasma generator. For this purpose, a design of experiment, covering a variety of parameters, is conducted. To identify the cause of the plasma jet fluctuations, the frequency spectra are obtained and subsequently interpreted by means of the fast Fourier transformation. To quantify the significance of the fluctuations on the particle in-flight properties, a new single numerical parameter is introduced. This parameter is based on the fraction of the time-dependent signal of the plasma jet in the relevant frequency range.

scholarly journals Tiny Cold Atmospheric Plasma Jet for Biomedical Applications

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 249
Author(s):  
Zhitong Chen ◽  
Richard Obenchain ◽  
Richard E. Wirz
Keyword(s):  
Biomedical Applications ◽  
Plasma Jet ◽  
Discharge Voltage ◽  
Plasma Jets ◽  
Atmospheric Plasma ◽  
Physical Parameters ◽  
Cold Atmospheric Plasma ◽  
Water Metal ◽  
Plasma Probe ◽  
Jet Nozzle

Conventional plasma jets for biomedical applications tend to have several drawbacks, such as high voltages, high gas delivery, large plasma probe volume, and the formation of discharge within the organ. Therefore, it is challenging to employ these jets inside a living organism’s body. Thus, we developed a single-electrode tiny plasma jet and evaluated its use for clinical biomedical applications. We investigated the effect of voltage input and flow rate on the jet length and studied the physical parameters of the plasma jet, including discharge voltage, average gas and subject temperature, and optical emissions via spectroscopy (OES). The interactions between the tiny plasma jet and five subjects (de-ionized (DI) water, metal, cardboard, pork belly, and pork muscle) were studied at distances of 10 mm and 15 mm from the jet nozzle. The results showed that the tiny plasma jet caused no damage or burning of tissues, and the ROS/RNS (reactive oxygen/nitrogen species) intensity increased when the distance was lowered from 15 mm to 10 mm. These initial observations establish the tiny plasma jet device as a potentially useful tool in clinical biomedical applications.

scholarly journals Cathodic protection of structures in seawater using solar panels

2019 ◽  
Vol 121 ◽  
pp. 02004
Author(s):  
Boris Borisovich Chernov ◽  
Van Mung Vu ◽  
Anac Maskharovich Nugmanov ◽  
Lyudmila Yuryevna Firsova
Keyword(s):  
Cathodic Protection ◽  
Sea Water ◽  
Cathode Current Density ◽  
Complete Agreement ◽  
Low Alloy Steels ◽  
Solar Panels ◽  
Protective Properties ◽  
Theoretical Concepts ◽  
Alloy Steels ◽  
Cathode Current

It is well known that the cathodic protection of structures in seawater is accompanied by the formation of calcareous deposits on them. In current study, we consider the physicochemical modelling of the formation of the deposit composition against cathode current density in seawater. The reliability of the model representations is confirmed by direct experiments. The work also studied the protective properties of the deposits with a different composition for low-alloy steels in natural sea water. It has been shown that the deposits of pure Mg(OH)2 and the deposits of CaCO3 + Mg(OH)2 had better protective ability against corrosion than the deposits of pure CaCO3. However, the deposits of Mg(OH)2 dissolved faster than the deposits of CaCO3 and CaCO3 + Mg(OH)2. Theoretical concepts and experiments on the laws governing the formation of the deposits and their protective properties are in complete agreement with each other. This allows to use the obtained patterns in the cathodic protection of structures in sea water using solar panels, forming standard deviations with predetermined protective properties in the daytime.

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