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Nasrullah IDRIS,Yong Inn LEE,Kiichiro KAGAWA,Koo Hendrik KURNIAWAN 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.2I
An electromagnetic phenomenon in terms of the induced current in a laser ablation process has been studied, and its potential application has been demonstrated. A new electrode configuration for measuring the induced current emerged due to the interaction between the electric lines of force and the laser-produced plasma has been devised. In this new electrode configuration, the induced current is detected by employing a circuit of electrodes, supplied with several hundred DC volts and placed above the sample surface in parallel, which is called the parallel configuration. This parallel configuration provides a far higher flexibility in comparison with the sandwiched configuration developed in our previous work. The induced current signal can be detected from various samples of any size, including metals and nonmetals. We found that the source of the induced current was the outer electrons in the plasma. This induced current is very useful as a unique monitoring method and promises many applications in laser microprocessing. In this work, this induced current method was applied for several monitoring purposes in laser material processing, such as for estimating the ablated amount, monitoring the penetration of a laser beam into processed materials, and determining the precise tight focusing position of the lens, in real time.
Ali Khumaeni,Kazuyoshi Kurihara,Zener Sukra Lie,Kiichiro Kagawa,이용인 한국물리학회 2014 Current Applied Physics Vol.14 No.3
Taking advantages of the special characteristics of a transversely excited atmospheric (TEA) CO2 laser, the analysis of sodium aerosol has been successfully conducted by using laser-induced gas plasma spectroscopy (LIGPS) method. In this study, the sodium aerosol was deposited on a nickel metal plate; the metal plate functions as a subtarget to initiate a gas plasma. When a pulsed TEA CO2 laser was focused on the metal surface, a large-volume and high-temperature gas plasma was induced. The fine particles of sodium then entered into the gas plasma region to be dissociated and excited. By using this technique, a semi quantitative analysis of sodium aerosol was made. The detection limit of sodium was approximately 200 ppb.
Confinement Effect in TEA CO2 Laser-Induced Plasma on Solid Organic Samples
Nasrullah Idris,Yong-Inn Lee,Hendrik Kurniawan,Kiichiro Kagawa,Maria Margaretha Suliyanti,Takao Kobayashi,Tjung Jie Lie 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.47 No.1
A Transversely Excited Atmospheric (TEA) CO2 laser beam (500 mJ, 200 ns) was focused on soft solid organic compounds under a low-pressure surrounding gas at around 2 Torr. We found that in order to induce a laser plasma from solid organic sample, such as plastics, the ablated atoms must be confined in a small hole (diameter of about 1 mm and depth of around 1 − 2 mm). Using our unique technique of density jump measurement (Rainbow Interferometer), we proved that the plasma is excited by a shock wave and that the confining hole works to induce and enhance a strong shock wave. The plasma has favorable characteristics for spectrochemical analysis due to its low spectral background and sharp emission lines; hence, the spectra can be taken using optical multichannel analyzer (OMA) without gated mode. By using the confinement effect, we detected chlorine ionic lines (Cl II at 479.4 nm, Cl II at 481.0 nm, and Cl II at 481.9 nm) with relatively strong emission intensities in the plastic sample containing chlorine.
Ali Khumaeni,Hideaki Niki,Yoji Deguchi,Kazuyoshi Kurihara,Kiichiro Kagawa,Yong Inn Lee 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.6
A novel technique for analysis of organic powder samples has been developed utilizing a metal subtarget-assisted gas plasma induced by using a TEA CO2 laser under He gas at atmospheric pressure. In this technique, the sample was filled in a hole (diameter of 8 mm and thickness of 2 mm) made of plastic plate (10 mm × 10 mm × 2 mm). The plastic holder filled with the sample was then sandwiched between two Cu plates (25 mm × 25 mm × 0.3 mm). One Cu plate, which had a hole with a diameter of 2.5 mm, functions to suppress the blowing-off of the sample, and the other served as a subtarget. When the TEA CO2 laser (1.5 J, 10.6 μm) was successively irradiated onto the sample’s surface passing through the hole of the Cu plate, a hole (2.5 mm in diameter and 2 mm in depth) was produced inside the sample, and the laser beam directly impinged on the subtarget. Once the laser beam had struck the subtarget, a strong subtarget-assisted gas plasma was induced. The initial gas plasma was confined in the hole region, and in later stage, the gas plasma expanded with a hemispherical shape (diameter of 1 cm). The fine particles of the sample were vaporized and effectively dissociated and atomized in the hole, and the atoms moved to the hemispherical plasma region to be excited through He meta-stable atoms. Using this method, an excellent linear calibration curve with zero intercept was made using a herb medicine containing different concentrations of Cr. The detection limits of Cr and Pb in the herb medicine were around 1 and 5 mg/kg, respectively. A novel technique for analysis of organic powder samples has been developed utilizing a metal subtarget-assisted gas plasma induced by using a TEA CO2 laser under He gas at atmospheric pressure. In this technique, the sample was filled in a hole (diameter of 8 mm and thickness of 2 mm) made of plastic plate (10 mm × 10 mm × 2 mm). The plastic holder filled with the sample was then sandwiched between two Cu plates (25 mm × 25 mm × 0.3 mm). One Cu plate, which had a hole with a diameter of 2.5 mm, functions to suppress the blowing-off of the sample, and the other served as a subtarget. When the TEA CO2 laser (1.5 J, 10.6 μm) was successively irradiated onto the sample’s surface passing through the hole of the Cu plate, a hole (2.5 mm in diameter and 2 mm in depth) was produced inside the sample, and the laser beam directly impinged on the subtarget. Once the laser beam had struck the subtarget, a strong subtarget-assisted gas plasma was induced. The initial gas plasma was confined in the hole region, and in later stage, the gas plasma expanded with a hemispherical shape (diameter of 1 cm). The fine particles of the sample were vaporized and effectively dissociated and atomized in the hole, and the atoms moved to the hemispherical plasma region to be excited through He meta-stable atoms. Using this method, an excellent linear calibration curve with zero intercept was made using a herb medicine containing different concentrations of Cr. The detection limits of Cr and Pb in the herb medicine were around 1 and 5 mg/kg, respectively.
Ali Khumaeni,Hideaki Niki,Ken-ichi Fukumoto,Yoji Deguchi,Kazuyoshi Kurihara,Kiichiro Kagawa,이용인 한국물리학회 2011 Current Applied Physics Vol.11 No.3
A sensitive analysis of powder samples has successfully been conducted using a strong gas breakdown plasma induced by assisting a metal mesh and a metal subtarget utilizing a transversely excited atmospheric (TEA) CO_2 laser; the metal mesh and the metal subtarget were placed on the front side and backside of the sample, respectively. The experiment was made at high pressure of air surrounding gas. In this study, the TEA CO_2 laser (1.5 J, 200 ns) was focused on the sample surface through the metal mesh. At the initial stage, a strong gas breakdown plasma was initiated by the assist of the metal mesh and finally enhanced by the metal subtarget after the laser beam struck on the metal subtarget’s surface through a hole inside the sample. The strong gas breakdown plasma can effectively be applied to completely dissociate and excite the ablated atoms from the sample. Using this technique, an excellent calibration curve with zero intercept has been made using herb medicine powder sample containing different concentrations of Zn. For sensitive analysis, a detection of hazard element of Cr in commercial supplement was also carried out. The detection limit of Cr was estimated to be around 0.6 mg/kg. This present technique has high possibility to realize the analysis of powder samples with high precision and high sensitivity.
Sub-target effect in film analysis using TEA CO2 laser-induced plasma
Yong-Inn Lee,Nasrullah Idris,Koo Hendrik Kurniawan,Tjung Jie Lie,Kenichiro Tsuyuki,Satoru Miura,Kiichiro Kagawa 한국물리학회 2007 Current Applied Physics Vol.7 No.5
A bioactive and biodegradable composite material consisting of hydroxyapatite (HA) and polyhydroxybutyrate (PHB) was investi-PHB composite which contained up to 40% by volume of particulate HA. The processing parameters for composite manufacture wereoptimized through thermal analyses of HA/PHB composite produced and production trials. The microstructure and properties of thecomposite were evaluated using various techniques. Form the results obtained, it is shown that good quality HA/PHB composite prod-ucts could be manufactured via the established production route.