Papers - SAKODA Tatsuya
-
Sakoda Tatsuya, Matsukuma Kunihiro, Sung Youl-Moon, Otsubo Kouji, Tahara Minoru, Nakashima Yoshihiro
Japanese Journal of Applied Physics 44 ( 4 ) 1730 - 1731 2005
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：公益社団法人 応用物理学会
To reduce the light reflection from surfaces of single-crystalline solar cells, a new surface texturing technique using a dielectric barrier discharge was proposed and examined on wet-textured surfaces of single-crystalline Si substrates. Minute uneven structures were additionally formed on the entire area of a wet-textured surface of pyramid-like shape. When the discharge voltage was 3.5 kV, the reflectance was less than 8% at wavelengths from 400 to 1000 nm and showed a minimum of 5.3% at 520 nm.
DOI： 10.1143/JJAP.44.1730
-
Activation of electrode surface on silicon solar cell using dielectric barrier discharge
Sakoda T., Matsukuma K., Araki I., Sung Y., Terakawa T., Furukawa K.
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers 43 ( 6 A ) 3275 - 3280 2004.6
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
To yield an activated electrode surface on a silicon solar cell, a surface treatment was examined using a dielectric barrier discharge instead of a wet cleaning technique. After the dry cleaning process using the dielectric barrier discharge, the surface state and the fill factor of the solar cell were evaluated. The results showed that the dielectric barrier discharge plasma could effectively activate the electrode surface of the solar cell in a relatively short time. Additionally, it was found that the surface treatment on finger electrodes played an essential role in the improvement of the fill factor.
-
Activation of Electrode Surface on Silicon Solar Cell Using Dielectric Barrier Discharge
Sakoda Tatsuya, Matsukuma Kunihiro, Araki Ichiro, Sung Youl-Moon, Terakawa Takeshi, Furukawa Katsuhiko
Japanese Journal of Applied Physics 43 ( 6 ) 3275 - 3280 2004
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：公益社団法人 応用物理学会
To yield an activated electrode surface on a silicon solar cell, a surface treatment was examined using a dielectric barrier discharge instead of a wet cleaning technique. After the dry cleaning process using the dielectric barrier discharge, the surface state and the fill factor of the solar cell were evaluated. The results showed that the dielectric barrier discharge plasma could effectively activate the electrode surface of the solar cell in a relatively short time. Additionally, it was found that the surface treatment on finger electrodes played an essential role in the improvement of the fill factor.
DOI： 10.1143/JJAP.43.3275
-
M. Otsubo, T. Hashigucchi, C. Honda, O. Takenouchi, T. Sakoda, Y. Hashimoto
IEEE on Dielectrics and Electrical Insulation 10 ( 6 ) 1053 - 1060 2003.12
Language：Japanese Publishing type：Research paper (scientific journal)
-
Transmission and detection of light diffraction signal by low-frequency ultrasonic wave
Sakoda T., Sonoda Y.
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers 42 ( 9 A ) 5821 - 5825 2003.9
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Measurement of low-frequency ultrasonic waves in water was examined by the light diffraction effect of a visible laser beam. This laser beam was much narrower than the ultrasonic wavelength. Characteristics of detected signals agreed well with the theoretical prediction based on Fraunhofer diffraction. As shown in the results, light diffraction waves transmitted through a polarization-maintaining fiber could be detected correctly. The results enable us to construct a novel optical fiber sensor which will be used for the detection of low-frequency ultrasonic waves as well as the transmission of light diffraction signals.
-
Spatial Distribution of Charged Particles in a Magnetic Neutral Loop Discharge Etcher
Y. M. Sung, T. Sakoda
Surface & Coating Technology 166 ( 2-3 ) 135 - 140 2003.3
Language：Japanese Publishing type：Research paper (scientific journal)
-
Observation of Copper Atoms Behavior in a Vacuum Arc Discharge using Laser Spectroscopy
Y. M.Sung, Y. Hayashi, Y. O. Yirenkyi, M. Otsubo, C. Honda, T. Sakoda
Journal of Vacuum Science & Technology A 21 ( 1 ) 180 - 185 2003.1
Language：Japanese Publishing type：Research paper (scientific journal)
DOI： 10.1116/1.1531141
-
Studies on electron behaviors at downstream region of a neutral loop discharge plasma
T. Sakoda, Y. M. Sung
Journal of Vacuum Science & Technology A 20 ( 6 ) 1964 - 1968 2002.11
Language：Japanese Publishing type：Research paper (scientific journal)
DOI： 10.1116/1.1513644
-
Two-dimensional Modeling and Optimization of a Neutral Loop Discharge Etcher in an Argon Plasma
Y. O. Yirenkyi, Y. M. Sung, M. Otsubo, C. Honda, T. Sakoda
Surface & Coating Technology 149 ( 2-3 ) 185 - 191 2002.1
Language：Japanese Publishing type：Research paper (scientific journal)
-
Sakoda T., Okraku-Yirenkyi Y., Sung Y., Otsubo M., Honda C.
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers 40 ( 11 ) 6607 - 6612 2001.11
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
In order to reveal the conditions required for the formation of a neutral loop discharge (NLD) plasma, distributions of excited atoms that are closely related to the distributions of the ionization rates were measured under various discharge conditions. Measurements of the distributions of these excited atoms were performed by laser induced fluorescence spectroscopy and optical emission spectroscopy. It was found that the results of these measurements were consistent with the theoretically predicted dependencies of electron heating on the magnetic field strength, the radio frequency (RF) electric field, and the frequency of the RF source. In addition, it was shown that the effects of electron-neutral collisions and of the finite size of the device set limitations on the formation of the NLD plasma.
-
Sakoda T., Okraku-Yirenkyi Y., Sung Y., Otsubo M., Honda C.
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers 40 ( 11 ) 6600 - 6606 2001.11
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
In this research, both the prebreakdown phenomena and the transient processes from the prebreakdown phenomena to the glow discharge in low-pressure Ar gas, Ar/N 2 and Ar/O 2 mixtures were investigated by electrical and optical methods. The prebreakdown phenomenon in the Ar/N 2 mixture was similar to that of Ar gas, and a pulseless component has been observed. The prebreakdown phenomenon in the Ar/O 2 mixture differed from those in the Ar gas and Ar/N 2 mixture, and formed a pulse discharge. Thus, the prebreakdown phenomenon in the Ar gas has been changed to pulse discharge by mixing a small amount of O 2 gas which played an important role in the formation of pulse discharge.
-
Y. O. Yirenkyi, Y. M. Sung, M. Otsubo, C. Honda, T. Sakoda
Journal of Vacuum Science & Technology A 19 ( 5 ) 2590 - 2595 2001.9
Language：Japanese Publishing type：Research paper (scientific journal)
DOI： 10.1116/1.1397467
-
Diagnostics of transformer oil by elastic waves
Sakoda T., Nieda H., Ando K.
Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) 135 ( 1 ) 1 - 7 2001.4
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi)
In the diagnostics of oil-immersed transformers, a chemical analysis of generated gases in the oil is generally performed, evaluating the kinds of gases and their quantities. This method, however, involves numerous procedures and is difficult to use in the field to diagnose the deterioration of oil. Considering the current state of the advanced information society, no deterioration in power apparatus should be permitted and the diagnosis of deterioration must be performed reliably while the equipment is energized. Therefore, we attempted to diagnose insulation oil based on analyses of elastic waves produced by a pulse discharge in the oil. This technique uses the behavior of elastic waves in liquid, in which an incident wave causes a high-frequency oscillation component with increasing gas content. In this investigation, elastic waves were detected on the outside surface of an oil tank at gas concentrations of 0 to 10%. The detected waves were analyzed by the fast Fourier transform. It was found that frequency spectra of 400 to 1000 kHz were increasingly evident when the gas concentration in oil was higher than ∼5%. This indicates that our new technique is useful for the diagnostics of oil-immersed transformers using the oscillation behavior of elastic waves produced by bubbles in oil. © 2001 Scripta Technica.
DOI： 10.1002/1520-6416(20010415)135:1<1::AID-EEJ1>3.0.CO;2-L
-
Characteristics of Elastic waves Caused by Corona Discharges in an Oil Immersed Pole Transformer
T. Sakoda, H. Nieda, K. Ando
IEEE on Dielectrics and Electrical Insulation 8 ( 2 ) 276 - 283 2001.4
Language：Japanese Publishing type：Research paper (scientific journal)
DOI： 10.1109/94.919956
-
Electric field calculation in composite dielectrics by first-order triangular surface charge method
Sakoda T., Nieda H., Ando K.
Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) 135 ( 1 ) 8 - 14 2001.4
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi)
This paper proposes a technique for calculating electric fields in composite dielectrics by the first-order triangular surface charge method. The proposed technique utilizes two kinds of triangular elements, namely, conforming and nonconforming elements: these are elements whose charge density is continuous and discontinuous between the neighboring elements, respectively. We basically apply nonconforming elements at the edges of a polyhedral shape where the normal component of electric field cannot be fixed. We have computed the electric field for a spherical or a rectangular solid dielectric in the presence of a uniform field. Comparison shows that the proposed first-order method works better than the zeroth-order one, and that, in particular, the combined use of conforming and nonconforming elements produces the highest accuracy. © 2001 Scripta Technica.
DOI： 10.1002/1520-6416(20010415)135:1<8::AID-EEJ2>3.0.CO;2-Y
-
FUKANO T., HORIGUCHI T., OTSUBO M., SUNG Y.M., SAKODA T., NIEDA H.
The Journal of the Institute of Electrical Installation Engineers of Japan 20 ( 10 ) 828 - 834 2000.10
Language：Japanese Publishing type：Research paper (scientific journal)
-
Studies on the optimum condition for the formation of a neutral loop discharge plasma
Y. M. Sung, K. Uchino, K.. Muraoka, T. Sakoda
Journal of Vacuum Science & Technology A 18 ( 5 ) 2149 - 2152 2000.9
Language：Japanese Publishing type：Research paper (scientific journal)
DOI： 10.1116/1.1286391
-
Analysis of acoustic emissions caused by the partial discharge in the insulation oil
Sakoda T., Arita T., Nieda H., Ando K.
IEEE International Conference on Conduction and Breakdown in Dielectric Liquids, ICDL 483 - 486 1999.12
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEEE International Conference on Conduction and Breakdown in Dielectric Liquids, ICDL
In order to diagnose the deterioration of insulation and evaluate its location in oil-filled pole transformer, measurements of elastic waves brought by corona discharges in oil were performed based on an acoustic emission (AE) technique. The detected signals in these measurements were analyzed by means of a fast Fourier transform (FFT) and their properties were discussed theoretically. It was found that the AE signals due to the Lamb waves of symmetrical mode caused in a thin steel tank could be easily recognized by the FFT analyses of initial stages of the detected AE signals. This suggests that the accuracy on location of the AE sources in the transformer would be improved. Also, it was shown that a low pass filter was effective to improve the accuracy of location.
-
Acoustic emissions caused by the corona discharge in an oil-tank
Sakoda T., Arita T., Nieda H., Otsubo M., Honda C., Ando K.
IEE Conference Publication 5 ( 467 ) 1999.12
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEE Conference Publication
Measurements of sonic and ultrasonic waves brought by corona discharges were performed based on an acoustic emission (AE) technique, to diagnose the deterioration of insulation and its location in an oil - filled pole transformer. The detected signals in these measurements were analyzed by means of a fast Fourier transform (FFT) and their properties were discussed. It was found that the AE signals due to the Lamb waves caused in a thin steel tank can be easily recognized by the FFT analyses of initial stages of the detected AE signals. This indicates that the accuracy on location of the AE sources in the transformer can be improved. Also, it was shown that a low pass filter was effective to improve the accuracy of location.
-
Studies of Elastic Waves Caused by Corona Discharges in Oil
T. Sakoda, T. Arita, H. Nieda, K. Ando, M. Otsubo, C. Honda
IEEE on Dielectrics and Electrical Insulation 6 ( 6 ) 825 - 830 1999.12
Language：Japanese Publishing type：Research paper (scientific journal)
DOI： 10.1109/94.822022