Trigger effect of the afterglow background medium after injection of the high speed plasma jet in the Fluxus and North Star experiments

2018 ◽  
Author(s):  
Boris Gavrilov ◽  
Julius Zetzer ◽  
Alexey Kovalev ◽  
Vladimir Rybakov ◽  
Yury Poklad
Keyword(s):  
High Speed ◽  
Plasma Jet ◽  
Trigger Effect ◽  
Background Medium

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.

Synthesizing Cubic Diamond Crystal Using DC Plasma Jet CVD

2019 ◽  
Vol 825 ◽  
pp. 71-76
Author(s):  
Hiromichi Toyota ◽  
Xia Zhu ◽  
Ryoya Shiraishi ◽  
Kazuto Nakajima ◽  
Yukiharu Iwamoto ◽  
...  
Keyword(s):  
High Speed ◽  
Catalytic Effect ◽  
Plasma Jet ◽  
Methanol Solution ◽  
Arc Plasma ◽  
Plasma Power ◽  
Experimental Conditions ◽  
Diamond Crystals ◽  
Dc Arc ◽  
Solution Gas

Diamond crystals are successfully synthesized by irradiating DC arc plasma jet to the substrate set in a methanol solution. It is the important procedure to preheat the substrate by inert Ar plasma jet before introducing the methanol solution gas to the plasma jet gun. The effects of two experimental conditions, the incident power and the substrates, are investigated. In the case of the Si substrate, cubic crystalline diamond grains of same size are synthesized at the plasma power of 470W. High speed hetero epitaxy is expected by using this method. In the case of the tungsten carbide substrate, diamond crystals and carbon nanotubes are simultaneously synthesized at the plasma power of 260W. The catalytic effect of Co binder in the substrate may cause the chemical reaction of the nanotube synthesis.

scholarly journals Subpixel Temperature Measurements in Plasma Jet Environments Using High-Speed Multispectral Pyrometry

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Tairan Fu ◽  
Jiangfan Liu ◽  
Minghao Duan ◽  
Sen Li
Keyword(s):  
Temperature Distribution ◽  
High Speed ◽  
Leading Edge ◽  
Plasma Jet ◽  
Temperature Measurements ◽  
Convective Heating ◽  
Small Data ◽  
Supersonic Plasma ◽  
Supersonic Plasma Jet ◽  
Spatial Temperature

A high-speed (2 kHz) near-infrared (1.0–1.65 μm) multispectral pyrometer was used for noninvasive measurements of the subpixel temperature distribution near the sharp leading edge of a wing exposed to a supersonic plasma jet. The multispectral pyrometer operating in the field measurement mode was able to measure the spatial temperature distribution. Multiple spectra were used to determine the temperature distributions in the measurement region. The spatial resolution of the multispectral pyrometer was not restricted to one “pixel” but was extended to subpixel accuracy (the temperature distribution inside one pixel in the image space corresponding to the point region in the object space). Thus, this system gives high-speed, multichannel, and long working time spatial temperature measurements with a small data stream from high-speed multispectral pyrometers. The temperature distribution of the leading edge of a ceramic wing was investigated with the leading edge exposed to extreme convective heating from a high-enthalpy plasma flow. Simultaneous measurements with a multispectral pyrometer and an imaging pyrometer verify the measurement accuracy of the subpixel temperature distribution. Thus, this multispectral pyrometry can provide in situ noninvasive temperature diagnostics in supersonic plasma jet environments.

Basic Characteristics of In-Liquid Plasma Jet and Electrode Damage

2017 ◽  
Vol 749 ◽  
pp. 76-80
Author(s):  
Xia Zhu ◽  
Taisuke Satoh ◽  
Hiromichi Toyota ◽  
Shinfuku Nomura ◽  
Yukiharu Iwamoto ◽  
...  
Keyword(s):  
High Speed ◽  
Arc Discharge ◽  
Basic Research ◽  
Plasma Jet ◽  
Waste Incineration ◽  
Practical Method ◽  
Discharge Voltage ◽  
Coupled Analysis ◽  
Temperature Plasma ◽  
Jet Characteristics

The most progress towards a practical method of fusing municipal waste incineration ash has been in the use of a plasma jet that employs arc discharge, a form of thermal plasma. However, a remaining problem is that stable plasma generation is prevented by melting of the nozzle of the plasma-jet torch by the high-temperature plasma flow. With the objective of developing high-speed fusion treatment for waste materials using an in-liquid plasma jet, basic research was conducted on plasma stability and the durability of plasma-jet torches, including electrodes and nozzles. Basic plasma jet characteristics such as the discharge voltage, current, and power value at the time of plasma jet generation were investigated experimentally. The relationship between the temperature distribution near the tip of a plasma jet torch and electrode damage was investigated by fluid-heat coupled analysis using the finite element method.

scholarly journals Investigation of the Arc-Anode Attachment Area by Utilizing a High-Speed Camera

2016 ◽  
Vol 3 (1) ◽  
pp. 1-4 ◽  
Author(s):  
P. Ondac ◽  
A. Maslani ◽  
M. Hrabovsky
Keyword(s):  
Flow Structure ◽  
Power Distribution ◽  
High Speed ◽  
Average Velocity ◽  
Anode Voltage ◽  
Plasma Jet ◽  
High Speed Camera ◽  
Plasma Arc ◽  
Hydrodynamic Waves ◽  
Dc Plasma

The arc-anode attachment in the DC plasma arc influences power distribution in the plasma, a lifespan of anode and flow structure of plasma jet. A movement of the attachment and the surrounding plasma was directly observed by using a high-speed camera (max. 1,080,000 fps). The observations were compared with cathode-anode voltage measurements (sample rate 80 MHz). We have directly measured the average velocity of the attachments and hydrodynamic waves above them, as well as the characteristic dwell times and dwell frequencies of the attachments.

scholarly journals Effect of External Magnetic Field on Long DC Arc Characteristics with Rng-shaped Anode

2021 ◽  
Vol 333 ◽  
pp. 03004
Author(s):  
Akio Hashizawa ◽  
Manabu Tanaka ◽  
Takayuki Watanabe ◽  
Tomohiro Koga
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
High Speed ◽  
Plasma Jet ◽  
Jet Flow ◽  
Critical Issue ◽  
Fluctuation Phenomena ◽  
High Speed Camera ◽  
Electrode Gap ◽  
Dc Arc

Fluctuation phenomena of plasma jet flow in an innovative long DC arc system with a ring-shaped anode were successfully clarified by a high-speed camera visualization. The long DC arc with long electrode gap distance more than 350 mm has been applied to gas decomposition due to its advantages of long plasma length, resulting in long residence time of treated gas. However, large heat loss at a conventional hemispherical-shaped anode was a critical issue in the long DC arc system. Therefore, the ring-shaped anode was utilized to convert large energy loss at the anode into the plasma jet flow. High-speed camera observation revealed the effect of external magnetic field on the fluctuation phenomena. Plasma jet fluctuates with the frequency of several tens Hz when the magnetic field was applied. These understanding of arc and plasma jet fluctuation enables to improve the capability of long DC arc system.

scholarly journals Experimental Investigation on the Influence of Target Physical Properties on an Impinging Plasma Jet

Plasma ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 369-379 ◽  
Author(s):  
Emanuele Simoncelli ◽  
Augusto Stancampiano ◽  
Marco Boselli ◽  
Matteo Gherardi ◽  
Vittorio Colombo
Keyword(s):  
Physical Properties ◽  
High Speed ◽  
Gas Flow ◽  
Light Emission ◽  
Fluid Dynamic ◽  
Imaging Techniques ◽  
Plasma Jet ◽  
Time Behavior ◽  
Charge Coupled Device ◽  
Intensified Charge Coupled Device

The present work aims to investigate the interaction between a plasma jet and targets with different physical properties. Electrical, morphological and fluid-dynamic characterizations were performed on a plasma jet impinging on metal, dielectric and liquid substrates by means of Intensified Charge-Coupled Device (ICCD) and high-speed Schlieren imaging techniques. The results highlight how the light emission of the discharge, its time behavior and morphology, and the plasma-induced turbulence in the flow are affected by the nature of the target. Surprisingly, the liquid target induces the formation of turbulent fronts in the gas flow similar to the metal target, although the dissipated power in the former case is lower than in the latter. On the other hand, the propagation velocity of the turbulent front is independent of the target nature and it is affected only by the working gas flow rate.

Capturing the Influence of Jet Fluctuations on Particles in Plasma Spraying

2021 ◽  
Author(s):  
K. Bobzin ◽  
H. Heinemann ◽  
A. O‘Brien
Keyword(s):  
Plasma Spraying ◽  
High Speed ◽  
High Sensitivity ◽  
Plasma Jet ◽  
Plasma Generator ◽  
Operating Conditions ◽  
High Temporal Resolution ◽  
Cathode Plasma ◽  
Novel Method ◽  
Plasma Sprayed

Abstract Instabilities and fluctuations of the plasma jet can have a significant influence on the particle in-flight temperatures and velocities, thus affecting the properties of plasma sprayed coatings. Presented in this paper is a novel method for capturing the effects particles are exposed to in the plasma spraying process. High-speed camera images of a plasma jet generated by a cascaded three cathode plasma generator (TriplexPro-210) are recorded for varying operating conditions. The images are processed using the inverse Abel transform. This transformation accounts for the fact that the images represent a 2-D projection and generates correct intensity values of the plasma jet images. These images are then combined with particle tracks resulting from CFD simulations of the plasma jet to match the particles path with the recorded plasma jet. This new method allows a precise description of the plasma intensity experienced by individual particles with a high temporal resolution. The results show a high sensitivity of the method, it can even detect the influence of the plasma jet originating from the cascaded triple arc plasma generator, which is considered as rather stable, on the particles.

Sign in / Sign up

Export Citation Format

Share Document