Spectroscopic Temperature Measurements in Direct Current Arc Plasma Jets Used in Thermal Spray Processing of Materials

Semenov, Sergey Y.; Cetegen, Baki M.

doi:10.1361/105996301770349411

Cited by 62 publications

(33 citation statements)

References 10 publications

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“…vaporization, dissociation, excitation and ionization [24]. In the literature dealing with plasma gas, temperature measurements are usually made using emission spectroscopy of excited plasma gas species [25]. Besides the qualitative determination of chemical composition of plasma from emission and absorption line identification, the measurement of electron and ion, or atom temperatures is the oldest application of spectroscopic methods to plasma and gaseous electrical discharge physics [26].…”

Section: Spectroscopic Temperature Measurement Techniquesmentioning

confidence: 99%

Spectroscopic investigation of arc over an ice surface /

Nekahi¹

2011

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Ice accumulation on insulators of overhead transmission lines and substations has been recognized as a major problem which may cause insulator flashover and power outages. This phenomenon starts with corona discharge activity and continues with the formation of partial arcs which may result in flashover. Due to the complexity of the process, resulting from surface interaction of discharge with the water film on the ice surface, is not yet fully understood. As for any other type of discharge, the knowledge of some parameters such as temperature and concentration of different species is necessary in order to describe the mechanisms involved. Moreover, to develop mathematical models for discharge propagation, an estimation of discharge channel conductivity is necessary. The current flows through this conductive channel and supplies the energy needed to sustain the ionization activity inside the channel. The conductivity of discharge channel is directly related to its temperature, which illustrates the need for discharge temperature measurements. Up to now, for an arc over an ice surface the temperature has been assumed to have a constant value of 5,000 K, but without any experimental support.The existence of Local Thermodynamic Equilibrium (LTE) is another important aspect for proposing theories and models, but this has not yet been verified for flashover on icecovered insulators. The verification of LTE condition requires information about temperature and concentration of different species, electron density and ionization level.The objective of this research is to augment our knowledge of flashover on icecovered insulators by measuring and calculating several important discharge column parameters. Measurement of rotational and excitation temperatures, and electron density during arc propagation are the first steps. The effect of discharge current, voltage type and polarity on the variation of the mentioned arc parameters should be also studied.Based on these data, the LTE condition could be examined.Spectroscopic plasma diagnostic is a non-destructive test method used to achieve the stated objectives. The emitted light from an arc over an ice surface was transmitted to a spectrometer. The time-resolved recorded spectra of arc were used to study the nature and concentration of ionized species. The gas and electron temperatures and electron densities were also measured using Boltzmann and Stark broadening methods.Measured rotational temperatures were found to vary from 4,000 K to 6,500 K, while the current increased from 200 mA to 700 mA during the discharge propagation. It was observed that under similar experimental conditions, the arc current intensity of DC+ arcs were hotter than that of DC-. Moreover, arc temperatures under AC voltage were lower than those of DC+, and close to that of DC-. The excitation temperature was measured at about 9,000 K and does not vary significantly with discharge current. As current increases, electron densities increased as well. For currents ranging from 200 mA to 700 mA, ...

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Section: Spectroscopic Temperature Measurement Techniquesmentioning

confidence: 99%

Spectroscopic investigation of arc over an ice surface /

Nekahi¹

2011

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“…Here, U ∞ is obtained from the measured plasma velocity field and ρ ∞ is obtained from plasma property database for the specific plasma gas composition [12] and the measured temperatures from emission spectroscopy [10]. Drag coefficient is evaluated from the correlation suggested by Yuen and Chen [13]:…”

Section: Model Descriptionmentioning

confidence: 99%

“…While a complete simulation of droplet heat-up in a plasma jet can be accomplished by a fully coupled numerical simulation of the plasma jet and the injected droplets, this approach requires a large amount of computational time and effort. Instead, we have chosen a hybrid approach wherein the plasma temperature and velocity fields are taken as inputs from the measured data [10,22]. In this approach, the influence of vaporizing droplets on the plasma field is assumed to be small as this would be the case for relatively small amounts of liquid injected into the plasma.…”

Section: Model Descriptionmentioning

confidence: 99%

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Modeling of plasma assisted formation of precipitates in zirconium containing liquid precursor droplets

Ozturk

Cetegen

2004

Materials Science and Engineering A

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This paper focuses on the modeling of heat and mass transfer in precursor containing droplets injected into a plasma jet and the estimation of precipitate formation in these droplets from the solute. A hybrid model is employed where the plasma temperature and velocity fields are obtained from previous experimental results and the heat and mass transfer around droplets are modeled. The precipitate formation zones from the zirconium acetate solution in these droplets are estimated based on the solute concentration field within the droplet. A simple homogeneous nucleation hypothesis is employed in predicting the regions of droplets where zirconia might precipitate. The effects of droplet size, injection velocity and angle, plasma conditions as well as the solute mass diffusivity are considered. Micrographs from single pass coating experiments give credible evidence of the presence of similar types of particle morphologies in agreement with this modeling study.

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“…One dimension of CCD was utilized to resolve the spectral information, while another dimension corresponded to the spatial information. Temperature distributions in radial or axial direction were reported (Semenov et al, 2001), although these obtained information was not sufficient to understand the temperature fluctuation of thermal plasmas. In recent, the imaging technique based on high-speed camera observation with imaging monochromators or appropriate band-pass filters has been developed.…”

Section: Introductionmentioning

confidence: 99%

Investigation of temperature characteristics of multiphase AC arc by high-speed visualization

Tanaka

Imatsuji

Hashizume

et al. 2017

JFST

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The objective of the present study is to understand fluctuation phenomena in a multiphase AC arc as a heat source for material processing based on the high-speed visualization technique of the temperature field. The multiphase AC arc is one of the most attractive thermal plasmas which possess extremely high temperature, high chemical reactivity, rapid quenching capability, and selectivity of the reaction atmosphere in accordance with required chemical reaction. In particular, the multiphase AC arc has a strong advantage on higher energy efficiency compared with other thermal plasmas. Therefore, this heat source has been applied to innovative material processing such as in-flight glass melting. However, the temporal and spatial characteristics of the multiphase AC arc have not been clarified although these are essential to control the characteristics of the products such as particle size distribution, yields of the desired materials. The high-speed visualization of the temperature field of the multiphase AC arc was conducted at 1x10 4 fps as typical framerate to observe the dynamic behavior of the multiphase AC arc in millisecond time scale. An optical system including the band-pass filters was combined with the high-speed camera to observe particular line emissions from atomic argon with negligible emissions from thermal plasma. The obtained experimental results indicated that the temperature of the multiphase AC arc was around 1.0x10 4 K. The arc temperature fluctuated in the range from 0.6x10 4 to 1.3x10 4 K. Consequently, the arc temperature in the multiphase AC arc is sufficiently high to treat the refractory metals and/or ceramics powders. Furthermore, the obtained temperature was well-validated by the conventional spectroscopic method with high accuracy.

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Spectroscopic Temperature Measurements in Direct Current Arc Plasma Jets Used in Thermal Spray Processing of Materials

Cited by 62 publications

References 10 publications

Spectroscopic investigation of arc over an ice surface /

Spectroscopic investigation of arc over an ice surface /

Modeling of plasma assisted formation of precipitates in zirconium containing liquid precursor droplets

Investigation of temperature characteristics of multiphase AC arc by high-speed visualization

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