scholarly journals INVESTIGATION OF GLOW DISCHARGE`S ENERGY PARAMETERS IN SMALL DIAMETER LONG TUBES

2019 ◽  
pp. 23-33
Author(s):  
Maksym Bolotov ◽  
Keyword(s):  
Glow Discharge ◽  
Hollow Cathode ◽  
Charged Particles ◽  
Small Diameter ◽  
Gas Discharge ◽  
Diffusion Welding ◽  
Temperature Plasma ◽  
Cathode Cavity ◽  
Inner Surface ◽  
Normal Glow Discharge

Urgency of the research. Cleaning the interior surfaces of the pipes is a mandatory operation, preceding the application of the coating using the methods of vacuum spraying. Significant disadvantages of traditionally applied methods of chemical and electrochemical purification of such surfaces conditioned the widespread use of plasma technologies based on low-temperature plasma glow discharge. Target setting. In particular, to date, the most common way to clean surfaces from various kinds of contaminants is ion spraying using a gas-discharge plasma of glow discharge. This cleaning method allows efficient removal of major types of contaminants such as fats, adsorbed water, gases, oxides, and allows processing surfaces of different configurations. Actual scientific researches and issues analysis. It is shown that the application of the glow discharge in the processes of purification and coating on the inner surface of pipes with a diameter of 56 mm in length 120 mm with the application of transverse magnetic field is shown. However, there are a number of difficulties, mainly related to the low productivity of the process, since the cleaning of the inner surface of such pipes was carried out for 60 minutes. Identification of unexplored parts of the general problem. It is possible to increase the processing efficiency by applying a glow discharge initiated in a hollow cathode. However, for today there are no data on the distribution of the concentration of charged particles inside the product, in which L >> d. The purpose of the work. The purpose of this work is a comparative analysis of stress-strain state (NDS) in the diffusion welding of compounds from heterogeneous materials, which occurs when heated in a normal glow discharge and glow discharge, initiated in a hollow cathode. The statement of basic materials. Using the probe method, the energy characteristics of the plasma of the glow discharge initiated in the hollow cathode were studied in relation to the conditions for the cleaning of the interior surfaces of long pipes of small diameter. It is shown that with a pressure in a gas-discharge chamber of 53 Pa and a discharge current of 0.075 A, a sufficiently dense plasma with a concentration of charged particles at the level of 1.6 ∙ 1010 cm-3 is formed in the investigated geometry of the cathode cavity, which is characterized by high heterogeneity in height of the cavity (40 ... 60 %). It is also shown that an effective mechanism of influence on the distribution of plasma in the middle of the cathode, in which L >> D is the change in the distance of the cathode anode, a decrease of which from 40 to 20 mm increases the uniformity to 15 ... 20 %, and the introduction of an additional anode ring in the discharge scheme - to 8 ... 10 %. Conclusions. It has been shown that the purification of the inner surface of long pipes of small diameter (in which L = 10D) by smoldering discharge using the effect of a hollow cathode is complicated by a number of factors, mainly due to the rather high heterogeneity of the distribution of the plasma inside the cathode cavity.

Generation of uniform low-temperature plasma in a pulsed non-self-sustained glow discharge with a large-area hollow cathode

2017 ◽  
Vol 43 (1) ◽  
pp. 67-74 ◽  
Author(s):  
Yu. H. Akhmadeev ◽  
V. V. Denisov ◽  
N. N. Koval ◽  
S. S. Kovalsky ◽  
I. V. Lopatin ◽  
...  
Keyword(s):  
Low Temperature ◽  
Glow Discharge ◽  
Hollow Cathode ◽  
Low Temperature Plasma ◽  
Large Area ◽  
Temperature Plasma

scholarly journals Influence of Electron Injection on the Characteristics of a Hollow Cathode Glow Discharge

2021 ◽  
Keyword(s):  
Glow Discharge ◽  
Hollow Cathode ◽  
Discharge Current ◽  
Cathode Surface ◽  
Electron Flow ◽  
Glow Discharge Plasma ◽  
Cathode Cavity ◽  
Main Discharge ◽  
Dark Space ◽  
Gas Pressures

The article presents the results of experimental studies of a glow discharge with a hollow cathode in helium and argon gases using an auxiliary discharge as an electron emitter. The authors proposed to make the electrode common for both discharges in the form of a cylindrical metal mesh. The advantage of this design is explained as follows. The connection between the discharges is carried out through holes in the grid with a geometric transparency of 0.2, which makes it possible not only to smoothly control the glow discharge current, but also to enhance the discharge current. Plasma is known to be one of the most efficient electron emitters; however, its use as a cathode in devices with a glow discharge at low gas pressures is complicated by the fact that a grid with small holes is required to separate the electron flow from the plasma, and it is impractical to use such a system in view of low mechanical strength of the grid Since the hollow cathode works effectively at low gas pressures, the release of an electron flux from the plasma of some auxiliary discharge is possible with much larger holes in the grid separating the plasma and the hollow cathode cavity. In this case, the grid can be made such that it can withstand sufficiently high thermal loads and can operate in typical discharge modes with a hollow cathode. The injection of electrons into the cathode cavity of the glow discharge changes the radial distribution of the glow intensity, the width of the cathode dark space, and other parameters of the plasma in the cathode cavity. The influence of electrons penetrating from the auxiliary discharge into the cathode cavity of the main discharge becomes significant when the current of these electrons is comparable to or exceeds the current of electrons leaving the grid cathode surface as a result of γ-processes. In parallel with the measurement of the optical and electrical characteristics of the hollow cathode glow discharge plasma, measurements of the electron concentration were carried out by the microwave sounding method. The entire current of the auxiliary discharge penetrates into the cavity of the main discharge; however, after acceleration in the cathode dark space, the electrons penetrating from the auxiliary discharge ionize gas atoms and noticeably increase the current of the main discharge. Additional ions formed due to the ionization of the gas by the injected electrons knock out new electrons from the cathode surface, which makes it possible to increase the discharge current.

scholarly journals Impact of the Samples’ Surface State on the Glow Discharge Stability in the Metals’ Treatment and Welding Processes

2021 ◽  
Vol 11 (4) ◽  
pp. 1765
Author(s):  
Maksym Bolotov ◽  
Gennady Bolotov ◽  
Serhii Stepenko ◽  
Pavlo Ihnatenko
Keyword(s):  
Glow Discharge ◽  
Cathode Surface ◽  
Physicochemical Characteristics ◽  
Diffusion Welding ◽  
Stable Form ◽  
Temperature Plasma ◽  
Surface Machining ◽  
Heating Source ◽  
Pre Treatment ◽  
Welding Processes

The low temperature plasma of glow discharge has found a widespread use as a heating source in welding and surface treatment of metals. The meticulous analysis of glow discharge’s instabilities in these processes allowed us to highlight the physicochemical characteristics of the cathode surface (the welded or treated samples) as one of the main reasons of its transition into an electric arc—as a more stable form of gas discharges. The prolonged arc action on the samples surfaces inevitably leads to the disruption of the technological process and, consequently, to undesirable overheating of samples. In this regard, the main aim of this work is to study the influence of the macro- and micro relief of the cathode on the stable glow discharge existence in the processes of metals treatment and diffusion welding. It has been analytically established and experimentally supported that the glow discharge’s stability is mainly affected by the sharp protrusions generated on the cathode surface because of samples pre-treatment by machining before welding. It has been established that the rough surface pre-treatment with the Rz about 60–80 µm decreases the pressure range of glow discharge sustainable existence from 1.33–13.3 kPa to 1.33–5.3 kPa compared with the surface machining with the Rz about 10 µm.

Comparison of plasma characteristics of high-power pulsed sputtering glow discharge and hollow-cathode discharge

2020 ◽  
Vol 60 (1) ◽  
pp. 015501
Author(s):  
Shoki Abe ◽  
Katsuyuki Takahashi ◽  
Seiji Mukaigawa ◽  
Koichi Takaki ◽  
Ken Yukimura
Keyword(s):  
Glow Discharge ◽  
High Power ◽  
Hollow Cathode ◽  
Hollow Cathode Discharge ◽  
Plasma Characteristics

Controlled gas-discharge device with cold hollow cathode

1971 ◽  
Vol 7 (3) ◽  
pp. 61 ◽  
Author(s):  
I.I. Aksenov ◽  
V.A. Belous ◽  
S.A. Smirnov
Keyword(s):  
Hollow Cathode ◽  
Gas Discharge ◽  
Discharge Device
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