Spectroscopic measurements of electron density of capillary plasma based on Stark broadening of hydrogen lines

Ashkenazy, J.; Kipper, R.; Caner, Mehmet

doi:10.1103/physreva.43.5568

Cited by 140 publications

(80 citation statements)

References 5 publications

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“…14,15 On the other hand, the electron density ͑n e ͒ was measured by the Stark broadening width of the Balmer H ␤ line that was emitted from the plasma. Based on the Stark broadening theory, 16,17 n e in a high-pressure plasma is related to the broadening width as 18 n e ͑cm −3 ͒ = 8.02 ϫ 10 12 ͑⌬ 1/2 / ␣ 1/2 ͒ 3/2 , where ⌬ 1/2 ͑Å͒ is the full width at half maximum of the spectral line profile, and ␣ 1/2 is the reduced wavelength ͑Å/cgs field strength͒, which is tabulated in Ref. 16.…”

Section: A Spatial Measurements Of Plasma Parametersmentioning

confidence: 99%

Parametric study of atmospheric pressure microwave-induced Ar∕O2 plasmas and the ambient air effect on the plasma

Moon

Choe

2006

Physics of Plasmas

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A torch type microwave-induced afterglow plasma was produced at atmospheric pressure using an open-ended fused silica concentric double tube assisted by Ar and O 2 supply gases. The plasma emerged from the end of the discharge tube and was exposed to ambient air. A parametric study of the plasma characteristics was performed by measuring the temperature, density, and plasma volume as the operational parameters such as microwave power, gas flow rate, and its composition were varied. The excitation temperature ͑T exc ͒ obtained from the Ar I emission spectrum ranged from 3010 to 4350 K and the rotational temperature ͑T rot ͒ measured from the OH and O 2 diatomic molecular spectra ranged from 2250 to 3550 K. The electron density ͑n e ͒ from the H ␤ Stark broadening width at the plasma core was in the range of 6.6 to 7.6ϫ 10 14 cm −3 . The two-dimensional distribution of T exc and T rot was also obtained. Experiments while varying the Ar and O 2 gas flow rate and the O 2 / Ar ratio showed that n e was reduced but T exc was increased as the O 2 flow rate was increased. Using an additional dielectric tube for shielding the plasma from the ambient air demonstrated a significantly enlarged plasma length and lower T rot due to the nitrogen entrainment, as compared to the unshielded case.

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Section: A Spatial Measurements Of Plasma Parametersmentioning

confidence: 99%

Parametric study of atmospheric pressure microwave-induced Ar∕O2 plasmas and the ambient air effect on the plasma

Moon

Choe

2006

Physics of Plasmas

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“…The peak shift and full width half maximum (FWHM) of the H α and H β , at 656.3 and 486.1 nm respectively, provide an indication of the electron density in the plasma [16]. As the applied power was increased from 1.2 to 2.4 kW, it was observed that the normalised FWHM and H α / H β peak ratio increased by approximately 6%.…”

Section: Sintering Conditionsmentioning

confidence: 86%

Rapid discharge sintering of nickel–diamond metal matrix composites

Twomey

Breen

Byrne

et al. 2011

Journal of Materials Processing Technology

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Publication information Journal of Materials Processing Technology, 211 (7): 1210-1216Publisher Elsevier Item record/more information http://hdl.handle.net/10197/5260 Publisher's statementThis is the author's version of a work that was accepted for publication in Journal of Materials Processing Technology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Materials Processing Technology, 211 (7) AbstractThere is considerable interest in processing technologies which can lead to more energy efficient sintering of abrasive metal matrix composites. In this study the use of a novel microwave plasma processing technique called Rapid Discharge Sintering (RDS) for sintering nickel-diamond metal matrix composites (MMCs) is evaluated. Nickel-diamond powder composites (80 -20 % by weight respectively) were uniaxially pressed into 20 mm discs at compaction pressures of 100, 200 and 300 MPa. The discs were sintered using a microwave plasma formed with hydrogen and hydrogen/nitrogen as the discharge gases. For comparison, discs were also sintered using a tube furnace in a gas flow of hydrogen and nitrogen (3:1). Discs pressed to 300 MPa were treated at both 850 and 1000 o C. The properties of the sintered nickel-diamond composites were characterised using density, flexural stress, hardness, wear resistance, SEM and XRD. The RDS samples sintered at 1000 o C achieved the maximum disc strength of approximately 470 MPa within a 20 minute chamber processing time, compared with 6 hours for furnace sintered samples. RDS samples exhibited increased hardness values and a finer nickel matrix over furnace sintered samples. RDS has shown the ability to process nickel-diamond MMCs without oxidation or graphitisation at higher temperatures. As a result, minimal diamond destruction was observed during abrasive wear testing for RDS samples.

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“…An increase in applied power resulted in an increase in plasma emission intensity ( Figure 2). The peak shift and full width half maximum (FWHM) of the H α and H β , at 656.3 and 486.1 nm respectively, indicate the electron density in the plasma [14]. As the applied power increases from 1.2 to 2.4 kW, no increase in the normalised FWHM was observed and the ratio of the two peaks (H α / H β ) remained almost constant at ≈ 5.3.…”

Section: Sintering Conditionsmentioning

confidence: 92%

Comparison of thermal and microwaveassisted plasma sintering of nickel–diamond composites

Twomey¹,

Breen²,

Byrne³

et al. 2010

Powder Metallurgy

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There is considerable interest in processing technologies which can lead to more energy efficient sintering of metal powders. Microwave sintering has recently been shown to reduce energy usage as the volumetric heating process is considerably more efficient than resistance heating. RF plasma sintering meanwhile has been shown to deliver heat via uniform excitation of the processing gas resulting in ion bombardment of the workpiece. In this study the use of a rapid, novel microwave-assisted plasma sintering (MaPS) technology for processing of nickel-diamond metal matrix composites is evaluated. Nickel powder and polycrystalline diamond were mixed to prepare 20 mm discs under uniaxial compaction pressures of 100, 200 and 300 MPa. The discs were fired in a low pressure microwave plasma under a hydrogen atmosphere. For comparison, discs were also sintered using conventional tube furnace firing. The MaPS sintering is very rapid with full disc strength of >1000N, based on 3-point bend tests, being achieved within 10 minutes compared with 8 hours for furnace treatment. This study demonstrates that the microwave-assisted plasma sintered discs produced similar or superior performance to discs fired using furnace firing conditions but with sintering cycle time reduced by up to 95%.

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Spectroscopic measurements of electron density of capillary plasma based on Stark broadening of hydrogen lines

Cited by 140 publications

References 5 publications

Parametric study of atmospheric pressure microwave-induced Ar∕O2 plasmas and the ambient air effect on the plasma

Parametric study of atmospheric pressure microwave-induced Ar∕O2 plasmas and the ambient air effect on the plasma

Rapid discharge sintering of nickel–diamond metal matrix composites

Comparison of thermal and microwaveassisted plasma sintering of nickel–diamond composites

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