Electrode erosion in plasma torches

Szente, R. N.; Munz, R. J.; Drouet, M.

doi:10.1007/bf01447029

Cited by 46 publications

(36 citation statements)

References 26 publications

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“…(10), we obtain V = KB TM ( 11 ) where K is a proportionality constant. Equation (11) is close to the experimentally obtained equation (3), namely, (VocB°8°5).…”

Section: Steam: the Effect Of Magnetic Field Strengthmentioning

confidence: 99%

Cathode erosion on copper electrodes in steam, hydrogen, and oxygen plasmas

Munz

Habelrih

1992

Plasma Chem Plasma Process

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Experimental data are presented for cathode erosion rates on copper cathodes .for magnetically rotated arcs in steam, and mixtures of steam, hydrogen, and oxygen with argon. Measurements were also made of the arc voltage and velocity. The erosion rates.for steam and oxygen plasmas were significantly lower than those.lbr argon and hydrogen. Pure steam and 10% oxygen in argon gave erosion rates o.f 2.3 and 6.1 l.tg/ C respectively while pure argon and 70% hydrogen in argon gave rates of 14.8 and 13.0 ~g/ C respectively. Erosion rates decreased with increasing arc velocities. The variation of arc velocity with operating conditions is described in terms of both aerodynamic and "surface drag" on the arc and arc root respectively.

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“…(10), we obtain V = KB TM ( 11 ) where K is a proportionality constant. Equation (11) is close to the experimentally obtained equation (3), namely, (VocB°8°5).…”

Section: Steam: the Effect Of Magnetic Field Strengthmentioning

confidence: 99%

Cathode erosion on copper electrodes in steam, hydrogen, and oxygen plasmas

Munz

Habelrih

1992

Plasma Chem Plasma Process

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“…Experiments have been reported by Szente et al [9], Brillhac et al [10,11], Coudert et al [7] and Dorier et al [12] linking electrode erosion from cooled copper electrodes as functions of arc parameters. Electrode erosion follows an inverse power law in arc root velocities i.e.…”

Section: Arc Root Movement and Electrode Erosionmentioning

confidence: 99%

Arc root dynamics in high power plasma torches — Evidence of chaotic behavior

Das

2000

Pramana - J Phys

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Although plasma torches have been commercially available for about 50 years, areas such as plasma gun design, process efficiency, reproducibility, plasma stability, torch lives etc. have remained mostly unattended. Recent torch developments have been focusing on the basic understanding of the plasma column and its dynamics inside the plasma torch, the interaction of plasma jet and the powders, the interaction of the plasma jet with surroundings and the impingement of the jet on the substrate. Two of the major causes of erratic and poor performance of a variety of thermal plasma processes are currently identified as the fluctuations arising out of the arc root movement on the electrodes inside the plasma torch and the fluid dynamic instabilities arising out of entrainment of the air into the plasma jet. This paper reviews the current state of understanding of these fluctuations as well as the dynamics of arc root movement in plasma torches. The work done at the author's laboratory on studying the fluctuations in arc voltage, arc current, acoustic emissions and optical emissions are also presented. These fluctuations are observed to be chaotic and interrelated. Real time monitoring and controlling the arc instabilities through chaos characterization parameters can greatly contribute to the understanding of electrode erosion as well as improvement of plasma torch lifetime.

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“…It is generally accepted that the source of such kind of instabilities is numerous: fluctuations of arc voltage, plasma gas composition, variations in powder feeding, entrainment of the surrounding gas, etc. [18][19][20][21][22][23]. Regarding the time scale, the instabilities can be imaginarily classified into two categories: high-frequency fluctuations, denoted as "uncertainty" which mainly results from the unstable discharge of arc [18] (Fig.…”

Section: Introductionmentioning

confidence: 99%

A Study of the Influence of the Surrounding Gas on the Plasma Jet and Coating Quality During Plasma Spraying

Liu

Ansar

Arnold

2017

Plasma Chem Plasma Process

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Coating quality is affected by arc and plume instabilities during plasma spraying. In closed chamber plasma spraying, gradual drift is one of the intermediate instabilities, which is mainly due to the electrode erosion. This work focuses on the source of the gradual drift of the plasma jet and the influence on coating quality. The ambient state inside the chamber was controlled by a ventilation system and a vacuum system. The variation in the plasma jet was observed by a particle flux image (PFI) device based on a CCD camera. The optical spectrum of the plasma plume was measured and analyzed through an optical spectrometer. The results indicated that the addition of hydrogen to plasma gas induced the change in the plasma jet length and width with changing rates depending on the chamber state and the ventilation power. With poor ventilation, the intensity of H α emission was found to become gradually stronger while H β and H γ were found to become weaker. On closing the chamber and remaining enough ventilation power, it was observed that the ambient gas slowly turned red. Simultaneously, the coating weight and thickness were slightly decreased meanwhile the porosity ratio was obviously increased. The red ambient gas has been proved to be able to acidify the city water with pH value decreased from 7 to 1~3. Without hydrogen, the plasma jet was found to be stable without reddening and variation, but the plasma enthalpy was unfortunately low.

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Electrode erosion in plasma torches

Cited by 46 publications

References 26 publications

Cathode erosion on copper electrodes in steam, hydrogen, and oxygen plasmas

Cathode erosion on copper electrodes in steam, hydrogen, and oxygen plasmas

Arc root dynamics in high power plasma torches — Evidence of chaotic behavior

A Study of the Influence of the Surrounding Gas on the Plasma Jet and Coating Quality During Plasma Spraying

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