THE ELECTRICAL BREAKDOWN OF SMALL GAPS IN VACUUM

1958 ◽  
Vol 36 (4) ◽  
pp. 476-493 ◽  
Author(s):  
A. S. Denholm
Keyword(s):  
Time Dependence ◽  
Breakdown Voltage ◽  
Discharge Current ◽  
Electrical Breakdown ◽  
Vacuum Discharge ◽  
Diffusion Pump ◽  
Hydrogen Discharge ◽  
Impulse Voltage ◽  
Vacuum Gap ◽  
Plateau Level

An investigation of the electrical breakdown in vacuum of small gaps subject to contamination by diffusion pump oil showed that the most consistent results were obtained when electrodes were conditioned by a hydrogen discharge. Even with this method of conditioning a few preliminary sparks were usually required before the breakdown voltage reached a plateau level, so that the vacuum discharge itself could affect the final values obtained. The circuit parameters which controlled the discharge current were found to influence the magnitude and consistency of the breakdown voltage appreciably.Direct, alternating, and impulse voltage tests showed that the time for which voltage was applied to the vacuum gap influenced the breakdown voltage, and curves are presented which give the insulation strength of the gap. Two possible explanations of the time dependence of the breakdown voltage are given.

scholarly journals Delayed Discharge Bridging Two Sputtering Modes from Modulated Pulsed Power Magnetron Sputtering (MPPMS) to Deep Oscillation Magnetron Sputtering (DOMS)

Plasma ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 239-251
Author(s):  
Masaomi Sanekata ◽  
Hiroshi Nishida ◽  
Tatsuya Watabe ◽  
Yuki Nakagomi ◽  
Yoshihiro Hirai ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Discharge Current ◽  
Electrical Breakdown ◽  
Pulsed Power ◽  
Current Waveform ◽  
Delayed Discharge ◽  
Plot Analysis ◽  
Delay Times ◽  
Discharge Behavior ◽  
Delayed Discharges

Delayed discharges due to electrical breakdown are observed in modulated pulsed pow er magnetron sputtering (MPPMS) plasma of titanium. The delayed discharge, which is remarkable with decreasing argon gas pressure, transforms the discharge current waveform from a standard modulated pulsed discharge current waveform to a comb-like discharge current waveform consisting of several pulses with high power. In addition, the delay times, consisting of statistical times and formative times in the delayed MPPMS discharges, are experimentally measured with the help of Laue plot analysis. The pressure dependence of delay times observed indicates that the delayed discharge behavior matches the breakdown characteristics well. In the present study, the delayed discharge dynamics of the comb-like discharge current waveform, which can be the origin of deep oscillation magnetron sputtering, are investigated based on measurement of the delay times and the characteristics of discharge current waveforms.

Effect of Water on Electrical Properties of Refined, Bleached, and Deodorized Palm Oil (RBDPO) as Electrical Insulating Material

2013 ◽  
Vol 64 (4) ◽  
Author(s):  
Nazera Ismail ◽  
Yanuar Z. Arief ◽  
Zuraimy Adzis ◽  
Shakira A. Azli ◽  
Abdul Azim A. Jamil ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Breakdown Voltage ◽  
Palm Oil ◽  
Pour Point ◽  
Electrical Breakdown ◽  
Dissipation Factor ◽  
Mineral Oil ◽  
Flash Point ◽  
Effect Of Water ◽  
Insulating Liquid

This paper describes the properties of refined, bleached, deodorized palm oil (RBDPO) as having the potential to be used as insulating liquid. There are several important properties such as electrical breakdown, dielectric dissipation factor, specific gravity, flash point, viscosity and pour point of RBDPO that was measured and compared to commercial mineral oil which is largely in current use as insulating liquid in power transformers. Experimental results of the electrical properties revealed that the average breakdown voltage of the RBDPO sample, without the addition of water at room temperature, is 13.368 kV. The result also revealed that due to effect of water, the breakdown voltage is lower than that of commercial mineral oil (Hyrax). However, the flash point and the pour point of RBDPO is very high compared to mineral oil thus giving it advantageous possibility to be used safely as insulating liquid. The results showed that RBDPO is greatly influenced by water, causing the breakdown voltage to decrease and the dissipation factor to increase; this is attributable to the high amounts of dissolved water.

Reduced breakdown voltage for in-liquid plasma discharges using moveable electrodes

2021 ◽  
Author(s):  
Rusen Zhou ◽  
Baowang Liu ◽  
Yiyang Li ◽  
Renwu Zhou ◽  
Wenshao Li ◽  
...  
Keyword(s):  
Breakdown Voltage ◽  
Discharge Current ◽  
Power Source ◽  
Industrial Applications ◽  
Electrode Configuration ◽  
Plasma Discharges ◽  
System Complexity ◽  
Gliding Arc

Abstract Minimizing the breakdown voltage and discharge current required to initiate direct in-liquid discharges, thus lowering power-source requirements and avoiding electrode ablation, is crucial for industrial applications of in-liquid plasma discharges. Here we demonstrate such considerable reductions by employing movable electrodes, without changing the electrode configuration or increasing the system complexity. The new mechanism is based on electrostatic electrode attraction resulting in a reduction in the discharge spacing by up to 6 times and facilitating a plasma initiation at lower breakdown voltages. The accumulated charges consumed by the discharge revert the electrodes to the initial positions, forming a gliding arc between the enlarged gaps and thus inhibiting current increases and electrode ablation.

Influence of cathode material type on the electrical breakdown behaviors of DC discharge

2020 ◽  
Vol 98 (8) ◽  
pp. 726-731
Author(s):  
F. Diab ◽  
W.H. Gaber ◽  
M.E. Abdel-kader ◽  
B.A. Soliman ◽  
M.A. Abd Al-Halim
Keyword(s):  
Cathode Material ◽  
Work Function ◽  
Breakdown Voltage ◽  
Cathode Materials ◽  
Electrical Breakdown ◽  
Ionization Efficiency ◽  
Parallel Plates ◽  
Maximum Value ◽  
Dc Discharge ◽  
Work Functions

Paschen curves were studied using different cathode materials such as magnesium, zinc, and carbon graphite by discharge in argon gas of a pressure range between 0.08 and 3 Torr using a parallel plates configuration. The first and second Townsend coefficients (α and γ, respectively) and the ionization efficiency (η) of different cathode materials were deduced from Paschen curves as a function of the reduced field (E/P). The minimum breakdown voltage was found to be about 242 V for Mg material, which has the lowest work function, while carbon graphite has a higher breakdown voltage of 283 V due to its higher work function. The second coefficient γ was increased as a function of E/P and has higher values for materials of lower work functions, and a similar trend of γ is obtained as a function of the ion mean energy. On the other hand, the first coefficient α has a reverse behavior with both E/P and the work function of the cathode materials compared with the second coefficient. The ionization efficiency of the three cathode materials is identical, as η depends only on the gas properties and not the cathode material. η has a maximum value of about 0.025 V−1 for an E/P of about 185 Vcm−1Torr−1, corresponding to the maximum ionizing ability of electrons. The validation of the breakdown results has been confirmed by conferring with other published experimental measurements.

scholarly journals Fabrication of Fe3O4@SiO2 Nanofluids with High Breakdown Voltage and Low Dielectric Loss

Coatings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 716
Author(s):  
Bin Du ◽  
Yu Shi ◽  
Qian Liu
Keyword(s):  
Dielectric Loss ◽  
Breakdown Voltage ◽  
Shell Thickness ◽  
Electrical Breakdown ◽  
Sio2 Nanoparticles ◽  
Electrical Equipment ◽  
Insulating Oil ◽  
Low Dielectric ◽  
Sio2 Shell ◽  
High Dielectric

Insulating oil modified by nanoparticle (often called nanofluids) has recently drawn considerable attention, especially concerning the improvement of electrical breakdown and thermal conductivity of the nanofluids. However, traditional insulating nanofluid often tends to high dielectric loss, which accelerates the ageing of nanofluids and limits its application in electrical equipment. In this paper, three core-shell Fe3O4@SiO2 nanoparticles with different SiO2 shell thickness were prepared and subsequently dispersed into insulating oil to achieve nanofluids. The dispersion stability, breakdown voltages and dielectric properties of these nanofluids were comparatively investigated. Experimental results show the alternating current (AC) and positive lightning breakdown voltage of nanofluids increased by 30.5% and 61%, respectively. Moreover, the SiO2 shell thickness of Fe3O4@SiO2 nanoparticle had significant effects on the dielectric loss of nanofluids.

Electrical Breakdown Voltage In a Mixed Gas

2001 ◽  
Vol 40 (Part 2, No. 3B) ◽  
pp. L295-L297 ◽  
Author(s):  
Han S. Uhm ◽  
Eun H. Choi ◽  
Guansup Cho ◽  
Ki W. Whang
Keyword(s):  
Breakdown Voltage ◽  
Electrical Breakdown ◽  
Mixed Gas

Source Parameters and Excitation in a Spark Discharge

1972 ◽  
Vol 26 (1) ◽  
pp. 17-40 ◽  
Author(s):  
J. P. Walters
Keyword(s):  
Mass Transport ◽  
Time Dependence ◽  
Discharge Current ◽  
Transport Model ◽  
Source Parameters ◽  
Excitation Condition ◽  
Mass Transport Model ◽  
Simple Mass ◽  
Excitation Processes ◽  
Parameter Dependent

Experiments are reported for two key lines of aluminum, sparked in nitrogen against graphite for a variety of discharge current waveforms, that suggest that changes in spark source parameters do not fundamentally change the excitation processes in the spark. A straightforward, “either-or” excitation condition is imposed on a simple mass transport model, calculated from measured velocities of electrode vapor in the spark, to predict the time dependence of a primary feature of radiation emitted in the Al II spectrum. The data combine to suggest that parameter-dependent excitation indices require re-examination in terms of the manner in which radiation emitted from the discharge is viewed by the spectrometer.

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