Enhanced ablation of small anodes in a carbon nanotube arc plasma

Fetterman, Abraham J.; Raitses, Yevgeny; Keidar, Michael

doi:10.1016/j.carbon.2008.05.018

Cited by 47 publications

(67 citation statements)

References 22 publications

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“…These observations are consistent with Ref. [16], in which enhanced ablation was observed at smaller anode diameters.…”

Section: Experiments and Resultssupporting

confidence: 82%

“…The ablation rate decreased with increasing anode diameter before becoming small and approximately constant [16], while the formation of the cathode deposit was found to be crucial in the operation of the arc [15]. The evaporation of the graphite anode and formation of the carbon deposit on the cathode are self-organized to maintain the current conduction in the arc.…”

Section: Discussionmentioning

confidence: 98%

“…Using the setup described in previous works [15,16], experiments were performed with a copper cathode of diameter 5 cm and graphite anodes with diameter between 6 and 12 mm.…”

Section: Experiments and Resultsmentioning

confidence: 99%

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Self-organisation Processes In The Carbon ARC For Nanosynthis

Ng¹,

Raitses²

2014

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The atmospheric pressure carbon arc in inert gases such as helium is an important method for the production of nanomaterials. It has recently been shown that the formation of the carbon deposit on the cathode from gaseous carbon plays a crucial role in the operation of the arc, reaching the high temperatures necessary for thermionic emission to take place even with low melting point cathodes. Based on observed ablation and deposition rates, we explore the implications of deposit formation on the energy balance at the cathode surface, and show how the operation of the arc is self-organised process. Our results suggest that the can arc operate in two different regimes, one of which has an important contribution from latent heat to the cathode energy balance. This regime is characterised by the enhanced ablation rate, which may be favourable for high yield synthesis of nanomaterials. The second regime has a small and approximately constant ablation rate with a negligible contribution from latent heat.

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“…These observations are consistent with Ref. [16], in which enhanced ablation was observed at smaller anode diameters.…”

Section: Experiments and Resultssupporting

confidence: 82%

Section: Discussionmentioning

confidence: 98%

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Self-organisation Processes In The Carbon ARC For Nanosynthis

Ng¹,

Raitses²

2014

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“…The contact area increases with increasing the anode diameter, thus the larger anode diameter means the larger anode cooling effect. According to the energy balance equation for carbon evaporation [29], the carbon evaporation rate decreases with increasing the anode diameter. Measured evaporation rates were 4.8, 10.6 and 27.3 mg·min −1 for different anode diameters of 30, 15 and 10 mm, respectively.…”

Section: Discussionmentioning

confidence: 99%

Selective preparation of polyhedral graphite particles and multi-wall carbon nanotubes by a transferred arc under atmospheric pressure

Liang

Shimizu

Tanaka

et al. 2012

Diamond and Related Materials

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“…The arc setup was designed and built for studying nanotube formation in an arc plasma [13]. It uses a movable graphite anode (0.2-1 cm diameter) and a brass cathode (2.5 cm diameter) ( Fig.…”

Section: Methodsmentioning

confidence: 99%

Raman spectroscopy of carbon dust samples from NSTX

Raitses

Skinner

Jiang

et al. 2008

Journal of Nuclear Materials

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The Raman spectrum of dust particles exposed to the NSTX plasma is different from the spectrum of unexposed particles scraped from an unused graphite tile. For the unexposed particles, the high energy G-mode peak (Raman shift $ 1580 cm À1 ) is much stronger than the defect-induced D-mode peak (Raman shift $ 1350 cm À1 ), a pattern that is consistent with Raman spectrum for commercial graphite materials. For dust particles exposed to the plasma, the ratio of G-mode to D-mode peaks is lower and becomes even less than 1. The Raman measurements indicate that the production of carbon dust particles in NSTX involves modifications of the physical and chemical structure of the original graphite material. These modifications are shown to be similar to those measured for carbon deposits from atmospheric pressure helium arc discharge with an ablating anode electrode made from a graphite tile material. We also demonstrate experimentally that heating to 2000-2700 K alone cannot explain the observed structural modifications indicating that they must be due to higher temperatures needed for graphite vaporization, which is followed either by condensation or some plasma-induced processes leading to the formation of more disordered forms of carbon material than the original graphite.

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Enhanced ablation of small anodes in a carbon nanotube arc plasma

Cited by 47 publications

References 22 publications

Self-organisation Processes In The Carbon ARC For Nanosynthis

Self-organisation Processes In The Carbon ARC For Nanosynthis

Selective preparation of polyhedral graphite particles and multi-wall carbon nanotubes by a transferred arc under atmospheric pressure

Raman spectroscopy of carbon dust samples from NSTX

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