| 1. |
Manabu Tanaka, Ryo Takenaka, Takafumi Okuma, Takayuki Watanabe, Development of Thermal Plasma Sourves with Diode-Rectification and Their Applications to Nanomaterial Fabrication, 24th Symposium on Application of Plasma Processes, IL16, 2023.02. |
| 2. |
Manabu Tanaka, Ryo Takenaka, Yuta Sogo, Aika Tamae, Takafumi Okuma, Takayuki Watanabe, Tsugio Matsuura, Juan-Pablo Trelles, Masaya Shigeta, Innovative Thermal Plasma Generation with Diode-Rectified AC Arc System and Its Applications, Innovative Thermal Plasma Generation with Diode-Rectified AC Arc System and Its Applications, 6th Asia-Pacific Conference on Plasma Physics, 2022.10, New thermal plasma sources have been successfully developed by diode-rectified AC arc under atmospheric pressure. Diode-rectification technique enables us to designe and control arc phenomena as well as electrode phenomena in high-intensity arc devices.
Planar thermal plasma jet has been successfully developed with diode-rectified AC arc system. Moreover, diode-rectified multiphase AC arc (DRMPA) has also been developed for the massive powder processing at high throughput. These new sources of thermal plasmas and their applications have been presented in this topical plenary talk.. |
| 3. |
Manabu Tanaka, Yuta Kugimiya, Takayuki Watanabe, and Tsugio Matsuura, Planar Thermal Plasma Jet in Diode-Rectified AC Arc System under Atmospheric Pressure, 47th IEEE International Conference on Plasma Sciences, 2020.12. |
| 4. |
Manabu Tanaka, Hiroki Maruyama, Yuta Kugimiya, Tsugio Matsuura, Takayuki Watanabe, Investigation of Temperature Fluctuation of Diode-Rectified Multiphase AC Arc by High-Speed Visualization, 18th Asia-Pacific Confederation of Chemical Engineering, 2019.09. |
| 5. |
Manabu Tanaka, Yuki Saito, Hiroki Maruyama, Takayuki Watanabe, High-Speed Visualization of Metal Oxide Precursor in Multiphase AC Arc during Nanoparticle Formation, 10th International Conference on Reactive Plasmas, 2019.07. |
| 6. |
Manabu Tanaka, Hiroki Maruyama, Taro Hashizume, Tsugio Matsuura, Takayuki Watanabe, Fluctuation Phenomena in Diode-Rectified Multiphase AC Arc for Improvement of Electrode Erosion, 24th International Symposium on Plasma Chemistry, 2019.06. |
| 7. |
Manabu Tanaka, Kohki Saga, Taro Hashizume,Tsugio Matsuura, Takayuki Watanabe, Improvement of Electrode Erosion Characteristics in Diode-Rectified Multiphase AC Arc, 23rd International Symposium on Plasma Chemistry, 2017.07, An innovative multiphase AC arc was drastically improved by diode-rectification technique. Conventionally, electrode erosion in AC arc originates from a lack of suitable electrode material because required properties for cathode and anode are different. To solve this problem, separation of AC electrodes into pairs of cathode and anode by diode-rectification was attempted. Diode-rectified MPA was then successfully established and erosion characteristics were drastically improved.. |
| 8. |
Tanaka Manabu, Yuji Nawata, Tomoyuki Imatsuji, Takayuki Watanabe, Dynamic Behavior of Metal Oxide Vapors in Multiphase AC Arc during Oxide Nanoparticle Fabrication Process, 26th Symposium of The Materials Research Society of Japan, 2016.12. |
| 9. |
Manabu Tanaka, Taro Hashizume, Tomoyuki Imatsuji, Yushi Nawata, Takayuki Watanabe, High-Speed Visualization of Evaporation Phenomena from Tungsten Based Electrode in Multi-Phase AC Arc, 9th International Conference on Reactive Plasmas, 2015.10. |
| 10. |
Taro Hashizume, Manabu Tanaka, Takayuki Watanabe, Droplet Ejection Mechanism from Tungsten Electrode in Multi-Phase AC Arc by High-Speed Visualization, 22nd International Symposium on Plasma Chemistry, 2015.07. |
| 11. |
Manabu Tanaka, Takayuki Watanabe, High-Speed Visualization of Electrode Phenomena in Thermal Plasma Processing, 5th International Conference on Microelectronics and Plasma Technology, 2014.07, A multi-phase AC arc has been developed to apply to innovative in-flight glass melting technology as a promising heat source because it possesses following advantages; the high energy efficiency, the large plasma volume, the low gas velocity, and so on. However, the understanding of multi-phase AC arc still remains to be improved for the practical use. In particular, electrode erosion is one of the most important issues to be solved. The purpose of this study is to investigate the electrode erosion mechanism of the multi-phase arc.
Multi-phase AC arc reactor mainly consisted of 12 electrodes, arc chamber, and AC power supply. The electrodes were made of tungsten (98 wt%) and thoria (2 wt%) with diameter of 6 mm. Argon shield gas was injected around the electrode to prevent them from the oxidation because the melting point of tungsten oxide is lower than that of metal tungsten. As the multi-phase arc discharge was generated under the atmospheric air except of the above mentioned argon, the plasma source gas was mainly air. The argon gas flow rate was changed to investigate the shield gas effect on the electrode erosion.
Combination of the high-speed camera and the band-pass filters system enables to measure the electrode temperature even during arc discharge, and to observe dynamic behavior of the vapors in the arc. In the present work, two synchronized high-speed cameras were applied to investigate the erosion mechanism. One of the systems was used to measure the electrode temperature, while another one was synchronized to observe the vapors in the arc.
The strong tungsten emission separated from the other emissions was successfully observed at the anodic period in the case of lower argon gas flow rate. Moreover, the synchronized temperature measurements revealed that the electrode tip temperature increased with decreasing the argon gas flow rate. This is because the discharge point was stabilized due to the constriction of arc in anodic period at the lower flow rate of shield gas. The droplet ejection from the molten electrode surface was also observed in the case of lower shield gas flow rate. The droplet ejection was contributed to the high electrode erosion of the multi-phase arc.
The high-speed visualization by the synchronized system of high-speed video cameras with appropriate band-pass filters is important to understand electrode phenomena during thermal plasma processing.. |
| 12. |
Manabu Tanaka, Tomoki Ikeba, Yaping Liu, Sooseok Choi, Takayuki Watanabe, Investigation on Electrode Erosion Mechanism of Multi-Phase AC Arc by High-Speed Camera Observation, 21st International Symposium on Plasma Chemistry, 2013.08. |
| 13. |
Manabu Tanaka, Takayuki Watanabe, Metal Hydride Formation from Molten Metal Surface by Ar-H2 Arc, 10th Asia-Pacific Conference on Plasma Science and Technology, 2010.07. |
