Bulletin of the American Physical Society
68th Annual Gaseous Electronics Conference/9th International Conference on Reactive Plasmas/33rd Symposium on Plasma Processing
Volume 60, Number 9
Monday–Friday, October 12–16, 2015; Honolulu, Hawaii
Session FT4: Thermal Plasmas; Materials Applications |
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Chair: Masaya Shigeta, Osaka University Room: 303 AB |
Tuesday, October 13, 2015 1:30PM - 2:00PM |
FT4.00001: Thermal Plasmas: Influence of Current Modulation on Process Performance Invited Speaker: Jochen Schein Due to the widespread industrial use of thermal plasmas in the field of joining, cutting and the application of coatings new challenges arise owed to the advent of new materials or the drive to reduce cost or improve quality. These challenges may be met by using technological innovations like innovative fast power supplies. In the presence of strong gas flows and a fixed cathodic attachment the anode attachment position is determined by an unstable balance between the drag force on the plasma column exerted by the gas and the Lorentz Force due to the system's magnetic field distribution, leading to a constant arc motion and arc voltage fluctuation. Thus by supplying a sufficiently high and steep current pulse a re-positioning might be initiated by a sudden change of the Lorentz Force thus an externally controlled movement of the arc would be possible. In wire arc spraying a pulsed current is imposed upon the DC supply of the wire arc system. It is observed that steep current increases tend to produce sudden current drops, indicating a jump of the arc. For a certain pulse frequency this pulsing leads to a controlled motion of the arc along the electrode surfaces. Coatings produced with this technology exhibited a lower porosity than DC sprayed coatings and a lower oxide content.\\[4pt] In collaboration with Alexander Atzberger and Michal Szulc, Universitaet der Bundeswehr Muenchen; Institute for plasma technology and mathematics (LPT) Neubiberg, Germany. [Preview Abstract] |
Tuesday, October 13, 2015 2:00PM - 2:15PM |
FT4.00002: Fundamental of a Planar Type of Inductively Coupled Thermal Plasma (ICTP) on a Substrate for a Large-area Materials Processings MaiKai SuanTial, Mika Akao, Hiromitsu Irie, Yuji Maruyama, Yasunori Tanaka, Yoshihiko Uesugi, Tatsuo Ishijima In this paper, the fundamental of a planar type Ar inductively coupled thermal plasmas (ICTP) with oxygen molecular gas have been studied on a substrate. Previously, we have developed a planar-ICTP torch with a rectangular quartz vessel with an air core coil or a ferrite core coil instead of a cylindrical tube for a large-area materials processing. For adoption of such a planar-ICTP to material processings, it needs to sustain the ICTP with molecular gases on a substrate stably. To consider the uniformity of the ICTP formed on the substrate, spectroscopic observation was carried out at 3 mm above the substrate. Results showed that the radiation intensities of specified O atomic lines were almost uniformly detected along the surface of the substrate. This means that O excited atoms, which are important radicals for thermal plasma oxidation, are present in planar-ICTP uniformly on the substrate. [Preview Abstract] |
Tuesday, October 13, 2015 2:15PM - 2:30PM |
FT4.00003: Potential Alternatives for Advanced Energy Material Processing in High Performance Li-ion Batteries (LIBs) via Atmospheric Pressure Plasma Treatment Jenq-Gong Duh, Shang-I Chuang, Chun-Kai Lan, Hao Yang, Hsien-Wei Chen A new processing technique by atmospheric pressure plasma (APP) jet treatment of LIBs was introduced. Ar/N$_{\mathrm{2}}$ plasma enhanced the high-rate anode performance of Li$_{\mathrm{4}}$Ti$_{\mathrm{5}}$O$_{\mathrm{12}}$. Oxygen vacancies were discovered and nitrogen doping were achieved by the surface reaction between pristine Li$_{\mathrm{4}}$Ti$_{\mathrm{5}}$O$_{\mathrm{12}}$ and plasma reactive species (N$^{\mathrm{\ast }}$ and N$_{\mathrm{2}}^{\mathrm{+}})$. Electrochemical impedance spectra confirm that plasma modification increases Li ions diffusivity and reduces internal charge-transfer resistance, leading to a superior capacity (132 mAh/g) and excellent stability with negligible capacity decay over 100 cycles under 10C rate. Besides 2D material surface treatment, a specially designed APP generator that are feasible to modify 3D TiO$_{\mathrm{2}}$ powders is proposed. The rate capacity of 20 min plasma treated TiO$_{\mathrm{2}}$ exhibited 20{\%} increment. Plasma diagnosis revealed that excited Ar and N$_{\mathrm{2}}$ was contributed to TiO$_{\mathrm{2}}$ surface reduction as companied by formation of oxygen vacancy. A higher amount of oxygen vacancy increased the chance for excited nitrogen doped onto surface of TiO$_{\mathrm{2}}$ particle. These findings promote the understanding of APP on processing anode materials in high performance LIBs. [Preview Abstract] |
Tuesday, October 13, 2015 2:30PM - 2:45PM |
FT4.00004: Investigation on evaporation of Ti feedstock and formation of precursor TiO molecules during TiO$_{2}$ nanopowder synthesis in induction thermal plasma with time-controlled feedstock injection Naoto Kodama, Kentaro Kita, Yosuke Ishisaka, Yasunori Tanaka, Yoshihiko Uesugi, Tatsuo Ishijima, Shiori Sueyasu, Keitaro Nakamura The method using inductively coupled thermal plasma(ICTP) is very effective for nanopowder(NPs) synthesis. However, NPs formation process in the ICTP torch has not been clarified. In this study, the two-dimensional spectroscopic observation was carried out for ICTP torch during TiO$_{2}$ NPs synthesis process with time-controlled feedstock injection. In order to investigate evaporation process of feedstock and formation process of precursor molecules, Ti feedstock was intermittently injected into the ICTP. Ti I(453.32 nm) and TiO(621 nm) were observed by using an imaging spectroscopic system. Observation results show that injected Ti feedstock was evaporated in the ICTP. Then, generated Ti atoms were transported to downstream of the torch by gas flow and were diffused to the radial direction by density gradient. High concentration of TiO molecular gas was formed only around central axis region in the torch. [Preview Abstract] |
Tuesday, October 13, 2015 2:45PM - 3:00PM |
FT4.00005: Time-dependent areal mass density for disc-shaped substrates in a corona-activated flow stream at atmospheric pressure for argon/acetylene admixture Shuzheng Xie, Rokibul Islam, Bashir Hussein, Karl Englund, Patrick Pedrow In this research we use a 40-needle array energized with 60 Hz AC voltage in the range 5 to 15 kV RMS. Plasma processing takes place downstream from a grounded planar screen (the opposing electrode). The needle-to-screen gap is in the range 4 to 10 cm and its E-field generates weakly ionized plasma via streamers and back corona. Deposited material is plasma-polymerized acetylene. Substrates are potassium bromide, mica, wood, paper, and gold-covered solids. Substrate chemical species influence the efficiency with which the disc amasses plasma-polymerized material, at least until the substrate is fully covered with film. Early plasma-polymerization is accompanied by nucleation-site-dominated nodules but longer term deposition results in a film that fully covers the substrate. We will report on time-dependent areal mass density associated with run times in the range 5-60 minutes. Film thickness will be measured using instruments that include visible light microscopy, TEM, and SEM. Others in our research group are studying areal mass density for early times (1-5 minutes) when nodule growth (at nucleation sites) dominates the deposition process. [Preview Abstract] |
Tuesday, October 13, 2015 3:00PM - 3:15PM |
FT4.00006: Nitrogen-Doped Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films/p-Silicon heterojunction Tsuyoshi Yoshitake, Abdelrahman Zkria Nitrogen-doped ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films were grown by coaxial arc plasma deposition method (CAPD), in ambient of nitrogen and hydrogen mixed gas. Heterojunction structures of n-UNCD/p-Si were prepared by growing n-doped UNCD thin films onto p-type Si (100) substrates. The heterojunction parameters were evaluated based on current--voltage and capacitance--voltage measurements at room temperature. The obtained results introduce the n-UNCD/p-Si heterojunction as a candidate for the electronic device applications [Preview Abstract] |
Tuesday, October 13, 2015 3:15PM - 3:30PM |
FT4.00007: Ablation and deposition processes in carbon arc discharge for nanosynthesis Yevgeny Raitses, Jonathan Ng, Valerian Nemchinsky, Yao-Wen Yeh, Sophia Gershman, Vlad Vekselman The anodic arc discharges with consumed anodes are used to produce various nanoparticles, including carbon nanotubes [1]. Our experiments with the carbon arc at atmospheric pressure helium demonstrate the dependence of the anode ablation rate on the anode diameter, which cannot be explained by changes of the current density at the anode. In particular, the anode ablation rate for narrow graphite anodes is significantly enhanced resulting in high deposition rates of carbonaceous products on the copper cathode [2]. The proposed model explains these results with interconnected steady-state models of the cathode and the anode processes [3]. Results of experimental validation of this model are presented.\\[4pt] [1] C. Journet, W. Maser, P. Bernier, A. Loiseau, et al. Nature \textbf{388} (6644) 756 (1997);\\[0pt] [2] .J. Ng, and Y. Raitses, J. App. Phys. \textbf{117}, 063303 (2015);\\[0pt] [3] V. Nemchinskiy and Y. Raitses, J. Phys. D: Appl. Phys. \textbf{48 }245202 (2015). [Preview Abstract] |
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