Motion of Anode Attachment and Fluctuations of Plasma Jet in Dc Arc Plasma Torch

Hrabovský, Milan; Konrád, M.; Kopecký, Vladimı́r; Hlína, J.; Beneš, J.; Veselý, E.

doi:10.1615/hightempmatproc.v1.i2.20

Cited by 18 publications

(9 citation statements)

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“…The third part, between the exit nozzle and the anode attachment, is an arc column in a free jet formed from mixture of argon with steam. In the experimental torch the length of the gas-stabilized arc column was about 6 mm, the length of the water-stabilized column was 50 mm, the length of arc in free jet between exit nozzle and anode attachment varied in the range of 6-24 mm as the anode attachment moved along the electrode surface in the restrike mode [6,7]. The anode disc was located out of the arc chamber about 4 mm downstream of the exit nozzle, the diameter of the exit nozzle was 5.7 mm.…”

Section: Experimental Systemmentioning

confidence: 99%

“…3 was recorded in the moment when anode attachment was in the position of the seventh diode from the nozzle exit. The attachment moved in the restrike mode [6,7] between positions of the third and eighth diodes. Thus, two first photodiodes recorded radiation of plasma jet upstream of the region of the anode attachment movement, where plasma jet fluctuations were less influenced by the attachment phenomena.…”

Section: Experimental Systemmentioning

confidence: 99%

“…The saw-tooth shape arc voltage fluctuations are characteristic for this restrike mode of the arc anode. Moreover, an anode jet is created in the anode attachment region and an interaction of this moving anode jet with the main plasma jet leads to disturbances in plasma flow in the jet [6,7]. The other important source of jet fluctuations is a ripple of arc current from power supply rectifier.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Resonant Excitation of Boundary Layer Instability of DC Arc Plasma Jet by Current Modulation

Kopecký

Hrabovský

2011

Plasma Chem Plasma Process

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Instabilities of thermal plasma jets were studied on the basis of analysis of plasma radiation fluctuations recorded by an array of high frequency photodiodes. Characteristic frequencies of jet oscillations were found and spatial distribution of amplitude of plasma fluctuations was determined. The influence of arc current ripple on plasma instabilities was investigated for two types of power supply-classical thyristor controlled unit with the frequency of the current ripple 300 Hz and the rectifier with the high frequency converter and frequency of the current modulation 30 kHz. Generation of boundary layer instability with the current modulation frequency and its harmonics was proved using fast Fourier transform, contour plots and phase portraits. It was found that the character of fluctuations of plasma jet was substantially influenced by current ripple with the frequency or its harmonics close to the frequency of oscillations generated by boundary layer instability.

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Section: Experimental Systemmentioning

confidence: 99%

Section: Experimental Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Resonant Excitation of Boundary Layer Instability of DC Arc Plasma Jet by Current Modulation

Kopecký

Hrabovský

2011

Plasma Chem Plasma Process

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“…The length of the gas-stabilized arc column was about 6 mm, and the length of the water-stabilized column was 50 mm. The length of the arc column in the free jet between the exit nozzle and the position of arc attachment varied from 4 to 24 mm as the anode attachment moved along the electrode surface in the restrike mode [15].…”

Section: Experimental Setup and Torch Configurationmentioning

confidence: 99%

Properties of Hybrid Water/Gas DC Arc Plasma Torch

Hrabovský

KopeckyKopecky²,

Sember

et al. 2006

IEEE Trans. Plasma Sci.

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A new type of plasma torch with combined stabilization of electric arc by water vortex and gas flow was investigated. This hybrid water/gas stabilization offers the possibility of adjusting plasma jet parameters within a wide range from high-enthalpy low-density plasmas typical for liquid stabilized torches to lower enthalpy higher density plasmas generated in gas stabilized torches. The torch was operated at an arc power from 22 to 130 kW with an exit centerline plasma velocity from 2 to 6.5 km/s and a plasma temperature from 14 000 K to 22 000 K. Moreover, gas flow in the cathode part protects a cathode tip and thus a consumable carbon cathode used in water torches could be replaced by a fixed tungsten cathode. The characteristics of the electric arc with combined gas/water stabilization were measured and the effect of gas properties and flow rate on plasma properties and gas-dynamic flow characteristics of the plasma jet were studied for argon, and mixtures of argon with hydrogen and nitrogen.Index Terms-Hybrid gas/water stabilization, plasma torch, thermal plasma jet, water-stabilized arc.

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“…Conventional direct current (dc) plasma torches are widely used in plasma spraying and have been shown to exhibit strong arc voltage fluctuations (Ref [1][2][3][4][5][6][7][8]. The electrical power dissipated within plasma forming gases strongly varies in time, resulting in nonhomogeneous treatment of solid particles injected in the plasma jet (Ref 9).…”

Section: Introductionmentioning

confidence: 99%

Improvement of Plasma Spray Torch Stability by Controlling Pressure and Voltage Dynamic Coupling

Rat

Coudert

2010

J Therm Spray Tech

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The development of coating formation processes involving electric arcs depends on process stability and the capacity to ensure a constant reproducibility of coating properties. This is particularly important when considering suspension plasma spraying or solution precursor plasma spraying. Submicron particles closely follow plasma instabilities and have nonhomogeneous plasma treatment. Recently, it has been shown that arc voltage fluctuations in direct-current (dc) plasma torches, showing dominant fluctuation frequencies between 4 and 6 kHz, are linked to pressure oscillations in the cathode cavity of the plasma torch. In this study, first, a method to isolate the different oscillation modes in arc voltage and pressure signals using signal processing methods is presented. Second, correlations between the different modes of oscillations are analyzed following the plasma torch operating parameters. Lastly, it is shown that the use of an acoustic stub, mounted on the torch body, decreases the amplitude of arc voltage fluctuations and slightly increases the mean voltage.

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Motion of Anode Attachment and Fluctuations of Plasma Jet in Dc Arc Plasma Torch

Cited by 18 publications

References 0 publications

Resonant Excitation of Boundary Layer Instability of DC Arc Plasma Jet by Current Modulation

Resonant Excitation of Boundary Layer Instability of DC Arc Plasma Jet by Current Modulation

Properties of Hybrid Water/Gas DC Arc Plasma Torch

Improvement of Plasma Spray Torch Stability by Controlling Pressure and Voltage Dynamic Coupling

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