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Journal Articles

Absorption spectroscopy of uranium plasma for remote isotope analysis of next-generation nuclear fuel

Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Maruyama, Yoichiro; Oba, Hironori; Tampo, Motonobu; Wakaida, Ikuo

Applied Physics A, 112(1), p.87 - 92, 2013/07

 Times Cited Count:13 Percentile:41.35(Materials Science, Multidisciplinary)

A uranium oxide sample was ablated by 2nd harmonic radiation from a Nd:YAG laser at a fluence of 0.5 J/cm$$^{2}$$. The temporal evolution of the ablation plume was investigated in vacuum and helium environments. In vacuum, the flow velocity perpendicular to the sample surface was determined to be 2.7 km/s for neutral atoms and 4.0 km/s for singly charged atoms. From the evolution of the plume in helium we found that an observation time of 3-5 $$mu$$s and an observation height of about 2.5 mm are most suited for obtaining higher sensitivity. Observation times less than 3 $$mu$$s were unsuitable for precise isotope analysis since the spectral modifications arising from the Doppler splitting effect are different between the two uranium isotopes. Using the established conditions, we evaluated the calibration curve linearity, limit of detection, and precision for three samples having different abundances of $$^{235}$$U.

Journal Articles

Laser ablation absorption spectroscopy for remote analysis of uranium

Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Maruyama, Yoichiro; Oba, Hironori; Tampo, Motonobu; Wakaida, Ikuo

Hyperfine Interactions, 216(1-3), p.71 - 77, 2013/04

 Times Cited Count:6 Percentile:9.61

To determine experimental conditions suitable for isotope analysis, we studied the plume dynamics of uranium. A uranium oxide sample was ablated by 2nd harmonic radiation from a Nd:YAG laser at a fluence of 0.5 J/cm$$^{2}$$. The temporal evolution of the ablation plume was investigated in 800 Pa helium environment. It was found that the observation at 3-5$$times$$10$$^{-6}$$s after the ablation at the height of about 2.5 mm are most suited for obtaining higher sensitivity. Using the established conditions, we obtained the limit of detection of the isotope ratio ($$^{235}$$U/$$^{238}$$U) to be 0.01%. In addition, the limit of detection of elemental abundance of uranium in uranium glass was also evaluated.

Journal Articles

Effect of defocusing on ablated volume of gadolinium oxide

Oba, Masaki; Maruyama, Yoichiro; Akaoka, Katsuaki; Miyabe, Masabumi; Wakaida, Ikuo

Japanese Journal of Applied Physics, 52(4), p.042403_1 - 042403_3, 2013/04

 Times Cited Count:1 Percentile:94.03(Physics, Applied)

We used nanosecond (ns) and femtosecond (fs) laser pulses to ablate gadolinium oxide samples and measured the ablated volume as a function of the laser pulse focal position. The defocusing effect of the ablated volume, which decreases as the ablation pulse focal position approaches the sample surface, was observed for both ns and fs pulses.

Journal Articles

Doppler-shifted optical absorption characterization of plume-lateral expansion in laser ablation of a cerium target

Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Maruyama, Yoichiro; Oba, Hironori; Tampo, Motonobu; Wakaida, Ikuo

Journal of Applied Physics, 112(12), p.123303_1 - 123303_10, 2012/12

 Times Cited Count:7 Percentile:63.4(Physics, Applied)

The temporal evolution of the ablation plume of cerium was investigated by absorption spectroscopy. Cerium oxide pellets were ablated in helium by 2nd harmonic radiation from a YAG laser. The lateral velocity of the plume was determined from the magnitude of the Doppler splitting of the absorption spectra. The velocities of neutral and ionized atoms were systematically investigated by varying several parameters. Temporal profiles of the transmittance signal were measured by detuning the probe laser frequency from the atomic resonant frequency in order to evaluate the temporal variation of the lateral velocity. On the basis of the drag force model, the slowing coefficients for atomic and ionic species in helium were evaluated along with the lateral velocity in a vacuum. This study may help in understanding the plume dynamics effect on deposited film properties as well as optimizing experimental conditions for ablation-based spectroscopic analysis.

Journal Articles

Double-pulse LIBS of gadolinium oxide ablated by femto- and nano-second laser pulses

Oba, Masaki; Maruyama, Yoichiro; Akaoka, Katsuaki; Miyabe, Masabumi; Wakaida, Ikuo

Applied Physics A, 101(3), p.545 - 549, 2010/11

 Times Cited Count:25 Percentile:26.36(Materials Science, Multidisciplinary)

Emission characteristics of gadolinium (Gd) oxide are studied, using ns and fs laser pulses for ablation in double-pulse laser induced breakdown spectroscopy (LIBS). In the current conditions of pulse energy and signal detection timing, emission intensity enhancement in the reheating mode is 25-fold, but the little effect can be observed in a pre-pulse mode. It is shown that the optimum focus position of the ablation pulse is about 5 mm apart from the sample surface in the reheating mode. Although little emission can be observed in single-pulse configuration with fs ablation pulses, the intense emission can be observed in the reheating mode in the double-pulse configuration.

JAEA Reports

Laser induced breakdown spectroscopy analysis of the uranium including calcium; Dependence of laser power (Contract research)

Akaoka, Katsuaki; Maruyama, Yoichiro; Oba, Masaki; Miyabe, Masabumi; Otobe, Haruyoshi; Wakaida, Ikuo

JAEA-Research 2010-036, 14 Pages, 2010/10

JAEA-Research-2010-036.pdf:2.18MB

For the remote analysis of low DF TRU (Decontamination Factor Transuranic) fuel, Laser Induced Breakdown Spectroscopy (LIBS) was applied to uranium oxide including a small amount of calcium oxide (3306ppm(weight)) as a sample, and the spectrum emitted from laser-breakdown plasma was examined. The characteristics, such as spectrum intensity and plasma excitation temperature as a function of laser power, were measured using time-resolved spectroscopy. As a result, the laser power of around 5 mJ was found optimum to obtain the stable intensity and narrow line width of spectrum.

Journal Articles

Spectroscopy of laser-produced cerium plasma for remote isotope analysis of nuclear fuel

Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Maruyama, Yoichiro; Wakaida, Ikuo

Applied Physics A, 101(1), p.65 - 70, 2010/10

 Times Cited Count:12 Percentile:49.01(Materials Science, Multidisciplinary)

A cerium oxide sample was ablated by 2nd harmonic radiation of Nd:YAG laser at a power density of 0.1 GW/cm$$^{2}$$. The velocities of the ablated atomic and ionic species were measured with the resonance absorption spectroscopy. It was found that the ablated ionic plume consists of at least two components having different velocities whereas the ablated atomic plume has roughly a single component. The flow velocity perpendicular to the sample surface in vacuum was determined to be 3.5 km/s for neutral atoms, and 4.7 km/s and 9.3 km/s for singly charged ions. From detailed plume evolution in ambient gas with several pressures we obtained some experimental conditions suitable for isotope analysis of atomic cerium.

JAEA Reports

Emission characteristics of gadolinium plasma in orthogonal double-pulse laser breakdown spectroscopy using femto and nanosecond laser (Contract research)

Maruyama, Yoichiro; Oba, Masaki; Akaoka, Katsuaki; Miyabe, Masabumi; Wakaida, Ikuo

JAEA-Research 2010-003, 19 Pages, 2010/07

JAEA-Research-2010-003.pdf:2.47MB

Emission characteristics of gadolinium plasma in the double-pulse LIBS using a femtosecond laser as an ablation source have been studied to achieve high sensitivity for analyzing next generation nuclear fuel in a future. In experiment, effects of the ablation laser focusing lens position and relative position of two plasmas were studied. The optimum ablation laser focusing lens position was about 22 mm from the sample surface, and the emission was maximized with the $$delta$$x of 1-1.2 mm and the $$delta$$y of 0.5-1 mm. As a result, about 200-times higher emission intensity in the double-pulse reheating mode was obtained than the emission in the single-pulse method. Moreover, the spectral width of the emission did not depend on the reheating laser pulse energy, and the high emission intensity could be obtained without the spectral broadening.

JAEA Reports

Laser induced breakdown spectroscopy of the uranium including calcium; Time resolved measurement spectroscopic analysis (Contract research)

Akaoka, Katsuaki; Maruyama, Yoichiro; Oba, Masaki; Miyabe, Masabumi; Otobe, Haruyoshi; Wakaida, Ikuo

JAEA-Research 2010-004, 13 Pages, 2010/05

JAEA-Research-2010-004.pdf:1.42MB

For the remote analysis of low DF TRU (Decontamination Factor Transuranic) fuel, Laser Breakdown Spectroscopy (LIBS) was applied to uranium oxide including a small amount of calcium oxide. The characteristics, such as spectrum intensity and plasma excitation temperature, were measured using time-resolved spectroscopy. As a result, in order to obtain the stable intensity of calcium spectrum for the uranium spectrum, it was found out that the optimum observation delay time of spectrum is 4 microseconds or more after laser irradiation.

JAEA Reports

Resonance absorption spectroscopy for laser-ablated lanthanide atom, 2; Expansion dynamics of laser ablation on cerium oxide (Contract research)

Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Maruyama, Yoichiro; Wakaida, Ikuo

JAEA-Research 2009-052, 30 Pages, 2010/02

JAEA-Research-2009-052.pdf:3.5MB

We have investigated propagation characteristics of the laser ablation plume produced from CeO$$_{2}$$ sample to optimize experimental conditions for isotope analysis for low-decontaminated TRU fuel. Vertical flow velocity and horizontal expansion velocity of the plume were evaluated with optical TOF measurement and Doppler splitting measurement. These measurements revealed that (1) the ionic plume in vacuum consists of two components having vertical velocities of 4.7 km/s and 9.3 km/s whereas the atomic plume has a single component having velocity of 3.5 km/s, and (2) these velocities for particles in various excited states are almost the same, (3) horizontal velocity is about 20% slower than the vertical one, (4) plume expansion in gas environment is described with a drag model, (5) under an optimum condition for isotope analysis, plume expansion is almost stopped and an ionization degree is significantly decreased.

Journal Articles

Basic study on remote analysis for next generation fuel by combination of laser induced breakdown spectroscopy (LIBS) and ablation initiated resonance absorption spectroscopy (AIRAS)

Wakaida, Ikuo; Akaoka, Katsuaki; Oba, Masaki; Maruyama, Yoichiro; Miyabe, Masabumi; Otobe, Haruyoshi; Niki, Hideaki*

Kaku Busshitsu Kanri Gakkai (INMM) Nippon Shibu Dai-30-Kai Nenji Taikai Rombunshu (CD-ROM), 9 Pages, 2010/01

In Japan Atomic Energy Agency, basic study on remote analysis by combination of LIBS for impurity measurement and AIRAS for isotope measurement is performed to apply rapid and on-site analysis of next generation fuel. For the impurity measurement of the sample with the matrix of Lanthanide or Uranium oxide which has complex spectrum structure, detection linearity to % order and the detection limit of order 100 ppm are obtained by the optimization of the measurement conditions of the delay time, gas pressure and by the deconvolution of the spectrum. For the isotope analysis, the laser system specialized for the resonance spectroscopy by frequency stabilized semiconductor tunable laser has been developed. And under the low pressure rare gas condition, spectrum resolution of 800 MHz is measured and the detection of $$^{235}$$U in Natural Uranium is realized.

JAEA Reports

Measurement of uranium spectrum using laser induced breakdown spectroscopy (Contract research)

Akaoka, Katsuaki; Maruyama, Yoichiro; Oba, Masaki; Miyabe, Masabumi; Otobe, Haruyoshi; Wakaida, Ikuo

JAEA-Research 2009-029, 49 Pages, 2009/10

JAEA-Research-2009-029.pdf:4.33MB

For applying Laser Induced Breakdown Spectroscopy (LIBS) to the analysis of nuclear fuel materials, it is very important to identify the emission spectrum and its intensity on impurities intermingled within complex emission spectra of matrix elements such as uranium (U) and plutonium (Pu). Then, the spectra of natural uranium are measured using LIBS, 165 atomic spectra and 381 single ion spectra were identified.

Journal Articles

Ablation-initiated isotope-selective atomic absorption spectroscopy of lanthanide elements

Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Maruyama, Yoichiro; Wakaida, Ikuo; Watanabe, Kazuo

AIP Conference Proceedings 1104, p.30 - 35, 2009/03

no abstracts in English

JAEA Reports

Laser-induced breakdown spectroscopy analysis of the copper added to gadolinium (Contract research)

Akaoka, Katsuaki; Maruyama, Yoichiro; Oba, Masaki; Miyabe, Masabumi; Wakaida, Ikuo

JAEA-Research 2008-081, 16 Pages, 2008/11

JAEA-Research-2008-081.pdf:3.19MB

For applying LIBS to the analysis of nuclear fuel materials, it is very important to investigate the analytical method to identify the emission spectrum and its intensity on impurities intermingled within complex emission spectra of matrix elements such as uranium and plutonium. Experiments using gadolinium as simulated sample, in which several 100 ppm of copper was contained, were performed and the analytical performance was estimated. The spectrum was decomposed into each peak of some spectra component on Gd and Cu. And the result, intensity of Cu component intermingled in Gd was determined quantitatively. In order to evaluate the linearity in the impurity analysis, the experiments with various concentration of Cu were carried out. The detection limit was determined to be about 70 ppm from the equivalent noise level which was estimated from the standard deviation in wavelength. The results curried out under the other laser conditions (intensity and wavelength) ware also evaluated.

JAEA Reports

Emission characteristics of copper plasma in laser-induced breakdown spectroscopy (Contract research)

Maruyama, Yoichiro; Wakaida, Ikuo

JAEA-Technology 2008-051, 13 Pages, 2008/07

JAEA-Technology-2008-051.pdf:2.07MB

Plasma emission characteristics of copper were studied by using Laser-Induced Breakdown Spectroscopy (LIBS). The intensity of plasma emission depended on the species of atmospheric gases, and the strongest plasma emission was obtained in the Ar atmosphere. And it was observed that the intensity reached its maximum at 1-2 microseconds after the ablation and decreased. The spectrum broadening due to Stark effect was observed and the spectral width varied with the observed time and the atmospheric gases, and the narrowest spectral width was obtained in He atmosphere. The plasma temperature calculated from spectral intensities reached around 10,000 K at 1-2 microseconds after the ablation and increased with increasing ablation laser energy.

JAEA Reports

Resonance absorption spectroscopy for laser-ablated lanthanide atom, 1; Optimized experimental conditions for isotope-selective absorption of gadolinium (Contract research)

Miyabe, Masabumi; Oba, Masaki; Iimura, Hideki; Akaoka, Katsuaki; Maruyama, Yoichiro; Wakaida, Ikuo; Watanabe, Kazuo

JAEA-Research 2008-056, 24 Pages, 2008/06

JAEA-Research-2008-056.pdf:5.1MB

For remote isotope analysis of low-decontaminated TRU fuel, we are developing an analytical technique on the basis of the resonance absorption spectroscopy for the laser-ablation plume. To improve isotopic selectivity and detection sensitivity of this technique, we measured absorption spectra of Gd atom with various conditions. As a result, high resolution spectrum was obtained from the observation of slow component of the plume produced under low-pressure rare-gas ambient. The observed narrowest linewidth of about 0.85 GHz was found to be close to the Doppler width estimated for Gd atom of room temperature. Furthermore, relaxation rate of higher meta-stable state was found to be faster than that of ground state, suggesting that use of the transition arising from ground state or lower meta-stable state is preferable for highly sensitive isotope analysis.

Journal Articles

0.5-kHz, 5-W optical parametric oscillator pumped by the second harmonic of a Nd:YAG laser

Maruyama, Yoichiro

Optical Engineering, 44(9), p.094202_1 - 094202_3, 2005/09

 Times Cited Count:1 Percentile:91.77(Optics)

A high average power BBO optical parametric oscillator pumped by a Nd:YAG laser second harmonic is demonstrated at the pulse repetition frequency of 0.5 kHz. Average power of 5.4 W (10.8 mJ) with the energy conversion efficiency of 45% is obtained for Type-I BBO OPO. The output power still increasing and undesirarble thermal effects are not observed.

Journal Articles

Numerical analysis of fractional distillation characteristics for radioactive metallic waste vaporized in the shape of atomic beam

Akaoka, Katsuaki; Maruyama, Yoichiro

Nippon Genshiryoku Gakkai Wabun Rombunshi, 4(2), p.127 - 134, 2005/06

The fractional distillation characteristics of the materials used for the reactor pressure vessel made of ASTM A302B and the structures in reactor made of SUS304 which are the radioactive metallic waste of Japan Power Demonstration Reactor (JPDR) were analyzed numerically. In the simulation, the vaporization rates of the components of the waste were calculated by using the Langmuir's equation and Henry's law. As the result of simulation, it was calculated that $$^{152}$$Eu, $$^{154}$$Eu, $$^{14}$$C and $$^{94}$$Nb can be reduced to less than clearance level by the fractional distillation. On the ASTM A302B case, it was pointed out that the other radioactive nuclei which are $$^{54}$$Mn, $$^{55}$$Fe, $$^{60}$$Co, $$^{59}$$Ni and $$^{63}$$Ni satisfy clearance level after 77 years cooling down. On the SUS304 case, it was pointed out that $$^{59}$$Ni and $$^{63}$$Ni must be separated to satisfy clearance level using isotope separation.

Journal Articles

Numerical analysis of fractional distillation for radioactive metal

Akaoka, Katsuaki; Maruyama, Yoichiro

RIST News, (39), p.23 - 31, 2005/03

For the separation of radionuclide from the radioactive metallic waste generated by the decommissioning of nuclear facilities, a new method combined with the distillation and laser separation is being studied. The characteristics of fractional distillation for duralumin were analyzed numerically using the Henry's law and the Langmuir's equation, and its result agreed well with the experiment. Next, the fractional distillation characteristics of the materials used for the structures in reactor made of SUS304 which are the radioactive metallic waste of Japan Power Demonstration Reactor (JPDR) were analyzed numerically. As the result of the simulation, it was calculated that the radioactive metallic waste will be reduced to less than 1/100.

JAEA Reports

Development of cavity length control system for high repetition rate Nd:YAG laser oscillator (Joint research)

Maruyama, Yoichiro; Kubomura, Hiroyuki*; Kasamatsu, Tadashi*; Matsuoka, Shinichi*; Nakano, Fumihiko*; Kan, Hirofumi*

JAERI-Tech 2004-056, 14 Pages, 2004/09

JAERI-Tech-2004-056.pdf:3.49MB

A high average power tunable solid state laser is pumped by the second harmonic of LD-pumped high repetition rate Nd:YAG laser consisting of a single-longitudinal-mode oscillator and amplifiers. To operate the Nd:YAG laser oscillator with a single-longitudinal-mode by injection seeding, the cavity length control is required to coincide the resonant frequency of Nd:YAG laser oscillator with the frequency of seeder. For this purpose, a cavity length control system of the Nd:YAG laser oscillator is developed and the characteristics are studied. With this system, the cavity length is controlled at the pulse repetition rate of 0.5 kHz and the single frequency operation for more than three hours is realized.

141 (Records 1-20 displayed on this page)