125 results on '"Yogo, A."'
Search Results
2. Automation of etch pit analyses on solid-state nuclear track detectors with machine learning for laser-driven ion acceleration.
- Author
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Taguchi, T., Minami, T., Hihara, T., Nikaido, F., Asai, T., Sakai, K., Abe, Y., Yogo, A., Arikawa, Y., Kohri, H., Tokiyasu, A. O., Chu, C. M., Woon, W. Y., Kodaira, S., Kanasaki, M., Fukuda, Y., and Kuramitsu, Y.
- Subjects
NUCLEAR track detectors ,MACHINE learning ,OPTICAL microscopes ,ION analysis ,AUTOMATION ,ACCELERATOR mass spectrometry ,IONS ,ETCHING - Abstract
Solid-state nuclear track detectors (SSNTDs) are often used as ion detectors in laser-driven ion acceleration experiments and are considered to be the most reliable ion diagnostics since they are sensitive only to ions and measure ions one by one. However, ion pit analyses require tremendous time and effort in chemical etching, microscope scanning, and ion pit identification by eyes. From a laser-driven ion acceleration experiment, there are typically millions of microscopic images, and it is practically impossible to analyze all of them by hand. This research aims to improve the efficiency and automation of SSNTD analyses for laser-driven ion acceleration. We use two sets of data obtained from calibration experiments with a conventional accelerator where ions with known nuclides and energies are generated and from actual laser experiments using SSNTDs. After chemical etching and scanning the SSNTDs with an optical microscope, we use machine learning to distinguish the ion etch pits from noises. From the results of the calibration experiment, we confirm highly accurate etch-pit detection with machine learning. We are also able to detect etch pits with machine learning from the laser-driven ion acceleration experiment, which is much noisier than calibration experiments. By using machine learning, we successfully identify ion etch pits ∼10
5 from more than 10 000 microscopic images with a precision of ≳95%. A million microscopic images can be examined with a recent entry-level computer within a day with high precision. Machine learning tremendously reduces the time consumption on ion etch pit analyses detected on SSNTDs. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
3. Development of an experimental platform for the investigation of laser-plasma interaction in conditions relevant to shock ignition regime
- Author
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T. Tamagawa, Y. Hironaka, K. Kawasaki, D. Tanaka, T. Idesaka, N. Ozaki, R. Kodama, R. Takizawa, S. Fujioka, A. Yogo, D. Batani, Ph. Nicolai, G. Cristoforetti, P. Koester, L. A. Gizzi, and K. Shigemori
- Subjects
Instrumentation - Abstract
T. Tamagawa, Y. Hironaka, K. Kawasaki, D. Tanaka, T. Idesaka, N. Ozaki, R. Kodama, R. Takizawa, S. Fujioka, A. Yogo, D. Batani, Ph. Nicolai, G. Cristoforetti, P. Koester, L. A. Gizzi, and K. Shigemori, "Development of an experimental platform for the investigation of laser–plasma interaction in conditions relevant to shock ignition regime", Review of Scientific Instruments 93, 063505 (2022) https://doi.org/10.1063/5.0089969, The shock ignition (SI) approach to inertial confinement fusion is a promising scheme for achieving energy production by nuclear fusion. SI relies on using a high intensity laser pulse (≈1016 W/cm2, with a duration of several hundred ps) at the end of the fuel compression stage. However, during laser-plasma interaction (LPI), several parametric instabilities, such as stimulated Raman scattering and two plasmon decay, nonlinearly generate hot electrons (HEs). The whole behavior of HE under SI conditions, including their generation, transport, and final absorption, is still unclear and needs further experimental investigation. This paper focuses on the development of an experimental platform for SI-related experiments, which simultaneously makes use of multiple diagnostics to characterize LPI and HE generation, transport, and energy deposition. Such diagnostics include optical spectrometers, streaked optical shadowgraph, an x-ray pinhole camera, a two-dimensional x-ray imager, a Cu Kα line spectrometer, two hot-electron spectrometers, a hard x-ray (bremsstrahlung) detector, and a streaked optical pyrometer. Diagnostics successfully operated simultaneously in single-shot mode, revealing the features of HEs under SI-relevant conditions.
- Published
- 2022
4. Predictive capability of material screening by fast neutron activation analysis using laser-driven neutron sources.
- Author
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Abe, Y., Nakao, A., Arikawa, Y., Morace, A., Mori, T., Lan, Z., Wei, T., Asano, S., Minami, T., Kuramitsu, Y., Habara, H., Shiraga, H., Fujioka, S., Nakai, M., and Yogo, A.
- Subjects
NUCLEAR activation analysis ,FAST neutrons ,NEUTRON sources ,NUCLEAR excitation ,NEUTRON irradiation - Abstract
Bright, short-pulsed neutron beams from laser-driven neutron sources (LANSs) provide a new perspective on material screening via fast neutron activation analysis (FNAA). FNAA is a nondestructive technique for determining material elemental composition based on nuclear excitation by fast neutron bombardment and subsequent spectral analysis of prompt γ-rays emitted by the active nuclei. Our recent experiments and simulations have shown that activation analysis can be used in practice with modest neutron fluences on the order of 10
5 n/cm2 , which is available with current laser technology. In addition, time-resolved γ-ray measurements combined with picosecond neutron probes from LANSs are effective in mitigating the issue of spectral interference between elements, enabling highly accurate screening of complex samples containing many elements. This paper describes the predictive capability of LANS-based activation analysis based on experimental demonstrations and spectral calculations with Monte Carlo simulations. [ABSTRACT FROM AUTHOR]- Published
- 2022
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5. Impulse and mass removal rate of aluminum target by nanosecond laser ablation in a wide range of ambient pressure.
- Author
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DucThuan Tran, Akifumi Yogo, Hiroaki Nishimura, and Koichi Mori
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IMPULSE (Physics) , *SHOCK waves , *SCHLIEREN devices , *LASER ablation , *WAVELENGTHS - Abstract
Impulse and mass removal rate of a spherical target irradiated by a nanosecond 1-μm-wavelength pulse laser are measured experimentally in air at ambient pressures from 10 Pa to 100 kPa. Shock waves resulting from expansion of the laser ablation plume are visualized by a Schlieren system. At the pressures between 100 Pa and 10 kPa, the shock wave is found to expand anisotropically affecting the impulse that is generated from both of ablation jet and blast wave energy. The mass removal rate is found constant up to 4 kPa and then peaking at 20 kPa because of the confinement effect. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
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6. Development of an experimental platform for the investigation of laser–plasma interaction in conditions relevant to shock ignition regime.
- Author
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Tamagawa, T., Hironaka, Y., Kawasaki, K., Tanaka, D., Idesaka, T., Ozaki, N., Kodama, R., Takizawa, R., Fujioka, S., Yogo, A., Batani, D., Nicolai, Ph., Cristoforetti, G., Koester, P., Gizzi, L. A., and Shigemori, K.
- Subjects
LASER-plasma interactions ,NUCLEAR energy ,STIMULATED Raman scattering ,NUCLEAR fusion ,PINHOLE cameras ,LASER pulses - Abstract
The shock ignition (SI) approach to inertial confinement fusion is a promising scheme for achieving energy production by nuclear fusion. SI relies on using a high intensity laser pulse (≈10
16 W/cm2 , with a duration of several hundred ps) at the end of the fuel compression stage. However, during laser–plasma interaction (LPI), several parametric instabilities, such as stimulated Raman scattering and two plasmon decay, nonlinearly generate hot electrons (HEs). The whole behavior of HE under SI conditions, including their generation, transport, and final absorption, is still unclear and needs further experimental investigation. This paper focuses on the development of an experimental platform for SI-related experiments, which simultaneously makes use of multiple diagnostics to characterize LPI and HE generation, transport, and energy deposition. Such diagnostics include optical spectrometers, streaked optical shadowgraph, an x-ray pinhole camera, a two-dimensional x-ray imager, a Cu Kα line spectrometer, two hot-electron spectrometers, a hard x-ray (bremsstrahlung) detector, and a streaked optical pyrometer. Diagnostics successfully operated simultaneously in single-shot mode, revealing the features of HEs under SI-relevant conditions. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
7. Non-destructive inspection of water or high-pressure hydrogen gas in metal pipes by the flash of neutrons and x rays generated by laser.
- Author
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Wei, Tianyun, Yogo, Akifumi, Hayakawa, Takehito, Arikawa, Yasunobu, Abe, Yuki, Nakanishi, Maiko, Mirfayzi, Seyed Reza, Lan, Zechen, Mori, Takato, Mima, Kunioki, Fujioka, Shinsuke, Murakami, Masakatsu, Nakai, Mitsuo, Nishimura, Hiroaki, Kar, Satyabrata, and Kodama, Ryosuke
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X-ray lasers , *HYDROGEN content of metals , *NATURAL gas pipelines , *THERMAL neutrons , *NEUTRONS , *NEUTRON radiography , *NEUTRON capture - Abstract
The thermal and epithermal neutrons are powerful probes to inspect water or high-pressure hydrogen gas because of their large scattering cross-sections with protons. Laser-driven neutron source, which is able to simultaneously emit different types of radiations such as x rays, can be used for neutron and x-ray radiography in the same laser shot. In this paper, we report the demonstration of non-destructive inspection for H2O contained within a stainless steel pipe using a laser-driven thermal neutron source, where water and stainless containers are detected by neutrons and x rays, respectively. The simulation result indicates that this method can also provide the capability to measure the hydrogen density in high-pressure hydrogen gas in metal containers. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
8. In vivo visualization method by absolute blood flow velocity based on speckle and fringe pattern using two-beam multipoint laser Doppler velocimetry.
- Author
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Tomoaki Kyoden, Shoji Naruki, Shunsuke Akiguchi, Hiroki Ishida, Tsugunobu Andoh, Yogo Takada, Noboru Momose, Tomotaka Homae, and Tadashi Hachiga
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VISUALIZATION ,BLOOD flow measurement ,LASER Doppler blood flowmetry ,PARTICLE image velocimetry ,DIFFRACTION patterns ,DOPPLER velocimetry - Abstract
Two-beam multipoint laser Doppler velocimetry (two-beam MLDV) is a non-invasive imaging technique able to provide an image of two-dimensional blood flow and has potential for observing cancer as previously demonstrated in a mouse model. In two-beam MLDV, the blood flow velocity can be estimated from red blood cells passing through a fringe pattern generated in the skin. The fringe pattern is created at the intersection of two beams in conventional LDV and two-beam MLDV. Being able to choose the depth position is an advantage of two-beam MLDV, and the position of a blood vessel can be identified in a three-dimensional space using this technique. Initially, we observed the fringe pattern in the skin, and the undeveloped or developed speckle pattern generated in a deeper position of the skin. The validity of the absolute velocity value detected by two-beam MLDV was verified while changing the number of layers of skin around a transparent flow channel. The absolute velocity value independent of direction was detected using the developed speckle pattern, which is created by the skin construct and two beams in the flow channel. Finally, we showed the relationship between the signal intensity and the fringe pattern, undeveloped speckle, or developed speckle pattern based on the skin depth. The Doppler signals were not detected at deeper positions in the skin, which qualitatively indicates the depth limit for two-beam MLDV. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
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9. Dosimetric calibration of GafChromic HD-V2, MD-V3, and EBT3 films for dose ranges up to 100 kGy.
- Author
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Abe, Y., Morace, A., Arikawa, Y., Mirfayzi, S. R., Golovin, D., Law, K. F. F., Fujioka, S., Yogo, A., and Nakai, M.
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NUCLEAR research ,CALIBRATION ,ABSORBED dose ,OPACITY (Optics) - Abstract
A dosimetric calibration of three types of radiochromic films (GafChromic
TM HD-V2, MD-V3, and EBT3) was carried out for absorbed doses (D) ranging up to 100 kGy using a 130 TBq C o 60 γ-ray source. The optical densities (ODs) of the irradiated films were acquired with the transmission-mode flatbed film scanner EPSON GT-X980. The calibration data were cross-checked using the 20-MeV proton beam from the azimuthally varying field cyclotron at the Research Center for Nuclear Physics in Osaka University. These experimental results not only present the measurable dose ranges of the films depending on the readout wavelength, but also show consistency with our hypothesis that the OD response curve [log(OD)–log(D) curve] is determined by the volumetric average of the absorption dose and does not strongly depend on the type of radiation for the excitation. [ABSTRACT FROM AUTHOR]- Published
- 2021
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10. The conceptual design of 1-ps time resolution neutron detector for fusion reaction history measurement at OMEGA and the National Ignition Facility.
- Author
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Arikawa, Yasunobu, Ota, Masato, Nakajima, Makoto, Shimizu, Tomoki, Segawa, Sadashi, Khoa Phan, Thanh Nhat, Sakawa, Youichi, Abe, Yuki, Morace, Alessio, Mirfayzi, Seyed Reza, Yogo, Akifumi, Fujioka, Shinsuke, Nakai, Mitsuo, Shiraga, Hiroyuki, Azechi, Hiroshi, Kodama, Ryosuke, Kan, Koichi, Frenje, Johan, Gatu Johnson, Maria, and Bose, Arijit
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INERTIAL confinement fusion ,NUCLEAR fusion ,NEUTRON counters ,CONCEPTUAL design ,SOLID-state lasers ,IMPULSE response - Abstract
The nuclear burn history provides critical information about the dynamics of the hot-spot formation and high-density fuel-shell assembly of an Inertial Confinement Fusion (ICF) implosion, as well as information on the impact of alpha heating, and a multitude of implosion failure mechanisms. Having this information is critical for assessing the energy-confinement time τE and performance of an implosion. As the confinement time of an ICF implosion is a few tens of picoseconds, less than 10-ps time resolution is required for an accurate measurement of the nuclear burn history. In this study, we propose a novel 1-ps time-resolution detection scheme based on the Pockels effect. In particular, a conceptual design for the experiment on the National Ignition Facility and OMEGA are elaborated upon herein. A small organic Pockels crystal "DAST" is designed to be positioned ∼5 mm from the ICF implosion, which is scanned by a chirped pulse generated by a femto-second laser transmitted through a polarization-maintained optical fiber. The originally linearly polarized laser is changed to an elliptically polarized laser by the Pockels crystal when exposed to neutrons, and the modulation of the polarization will be analyzed. Our study using 35-MeV electrons showed that the system impulse response is 0.6 ps. The response time is orders of magnitude shorter than current systems. Through measurements of the nuclear burn history with unprecedented time resolution, this system will help for a better understanding of the dynamics of the hot-spot formation, high-density fuel-shell assembly, and the physics of thermonuclear burn wave propagation. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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11. Ferroelectric properties of chemically synthesized perovskite BiFeO3–PbTiO3 thin films.
- Author
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Sakamoto, Wataru, Iwata, Asaki, and Yogo, Toshinobu
- Subjects
FERROELECTRICITY ,PEROVSKITE ,THIN films ,SUBSTRATES (Materials science) ,ELECTRIC fields ,HYSTERESIS loop ,LOW temperatures - Abstract
Ferroelectric BiFeO
3 –PbTiO3 thin films with near morphotropic phase boundary composition were synthesized on Pt/TiOx /SiO2 /Si substrates by chemical solution deposition. Perovskite BiFeO3 –PbTiO3 single-phase thin films were successfully fabricated at 600 °C by optimizing several processing conditions, such as the PbTiO3 content. Typical ferroelectric polarization-electric field (P-E) hysteresis loops were observed for (1-x)BiFeO3 –xPbTiO3 (x=0.2, 0.3, 0.4, 0.5) thin films, which contained some leakage current components at room temperature. In the low temperature region, the BiFeO3 –PbTiO3 thin films demonstrated improved insulating resistance and exhibited relatively saturated P-E hysteresis loops. Among these films, 0.7BiFeO3 -0.3PbTiO3 thin films exhibited the largest remanent polarization, and the remanent polarization (Pr ) and coercive field (Ec ) at -190 °C were approximately 60 μC/cm2 and 230 kV/cm, respectively. Furthermore, Mn doping of the BiFeO3 –PbTiO3 thin films was effective in changing the dominant leakage current factors and improving the ferroelectric properties of the resultant thin films at room temperature. The Pr and Ec values of 5 mol % Mn-doped 0.7BiFeO3 -0.3PbTiO3 films at room temperature were approximately 40 μC/cm2 and 100 kV/cm, respectively. Potentially large remanent polarization (∼90 μC/cm2 ) was also demonstrated by the BF-PT thin films. [ABSTRACT FROM AUTHOR]- Published
- 2008
- Full Text
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12. Production of intense, pulsed, and point-like neutron source from deuterated plastic cavity by mono-directional kilo-joule laser irradiation.
- Author
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Abe, Y., Sunahara, A., Lee, S., Yanagawa, T., Zhang, Z., Arikawa, Y., Morace, A., Nagai, T., Ikenouchi, T., Tosaki, S., Kojima, S., Sakata, S., Satoh, N., Watari, T., Nishihara, K., Kawashima, T., Yogo, A., Sakagami, H., Shiraga, H., and Nishimura, H.
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NEUTRON sources ,LASER beams ,LASER ablation ,NEUTRON flux ,NUCLEAR fusion ,NEUTRON radiography - Abstract
This paper reports an experimental investigation of a scheme to produce an intense, pulsed, pointlike, and quasi-monoenergy neutron source. In this scheme, the inner wall of a deuterated plastic spherical cavity is mono-directionally irradiated by a 2.4 kJ laser beam through an open-tip gold cone inserted into the cavity. The whole inner wall of the cavity is illuminated by laser light owing to multiple laser reflections, and the laser-ablated plasma stagnates near the center of the cavity, at which a several keV hot spot is generated. Thermonuclear and beam D-D fusion reactions occur in the hot spot. We have demonstrated the neutron yield exceeding 107 neutrons per pulse from a<100 μm diameter hot spot with the deuterated plastic cavity and mono-directional GEKKO-XII laser irradiation. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
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13. The Bacterial Diversity Investigation in Oil Palm Plantation using Terminal Restriction Length Polymorphism.
- Author
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Situmorang, Elizabeth Caroline, Nugroho, Yogo Adhi, Prameswara, Andriessa, Andarini, Esti, Hartono, Setyobudi, Roy Hendroko, Toruan-Mathius, Nurita, and Liwang, Tony
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BACTERIAL diversity , *MICROBIAL diversity , *OIL palm , *GENETIC polymorphisms , *BIODIVERSITY - Abstract
Oil palms ((Elaeis guineensis Jacq.), have been widely cultivated in Sumatera for over two planting generations and occupied lands with various soil characteristics. In order to investigate microbial diversity in various soil characteristics of oil palm plantation, a molecular analysis called Terminal Restriction Length Polymorphism (T-RFLP) was adopted. The aim of this research was to analyze the bacterial diversity within several oil palm plantations in Sumatera. DNA extraction was performed using soil DNA extraction kit and analysis was performed using fragment analysis following T-RFLP techniques. Data analysis was performed using MICA III public database. The result showed that soil samples were grouped into two clusters based on their chemical properties. Both HhaI and HinfI digestions affected the number of culturable bacteria dominancy. HhaI was more suitable for revealing a possible culturable genera and species abundance. Dominant genera were detected in each cluster. Cluster-2, which consisted of peat soils, was dominated by Clostridium, Burkholderia, Catenibacterium and Pasteuria. As the diversity of microbes reveals soil fertility, the result showed that metagenomic approach could be used to predict soil fertility indicator, in order to improve agricultural practices for oil palm cultivation. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
14. Fast ion acceleration in a foil plasma heated by a multi-picosecond high intensity laser.
- Author
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Natsumi Iwata, Kunioki Mima, Yasuhiko Sentoku, Akifumi Yogo, Hideo Nagatomo, Hiroaki Nishimura, and Hiroshi Azechi
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FAST ions ,LASER plasmas ,PICOSECOND pulses ,ULTRASHORT laser pulses ,ELECTRON temperature - Abstract
We study the one-dimensional expansion of a thin foil plasma irradiated by a high intensity laser with multi-picosecond (ps) pulse durations by using particle-in-cell simulation. Electrons are found to recirculate around the expanding plasma for many times, which results in stochastic heating leading to increase of the electron temperature in the multi-ps time scale beyond the ponderomotive scaling. The conventional isothermal model cannot describe such an expansion of plasmas in the long time scale. We here developed a non-isothermal plasma expansion theory that takes the time dependence of electron temperature into account for describing the multi-ps interactions in one-dimensional geometry. By assuming that the time scale of electron temperature evolution is slow compared with the plasma expansion time scale, we derived a non-self-similar solution. The time evolution of ion maximum energy obtained by the non-isothermal theory explains the details of that observed in the simulation. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
15. Upper Generalized Exponents of Two-colored Primitive Extremal Ministrong Digraphs.
- Author
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Hussein, Ismail, Prasetyo, Yogo D., and Suwilo, Saib
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GRAPH coloring , *GENERALIZABILITY theory , *DIRECTED graphs , *SUBSET selection , *MATHEMATICAL bounds , *EXPONENTS - Abstract
A two-colored digraph is a digraph each of whose arcs is colored by red or blue. An (h,k)-walk in a two-colored digraph is a walk consisting of h red arcs and k blue arcs. A two-colored digraph is primitive provided that for each pair of vertices u and v there exists an (h,k)-walk from u to v and from v to u. The smallest of such positive integer h+k is called the exponent of D(2). Let D(2) be a primitive two colored digraph and let X be a nonempty subset of V(D(2)). The set exponent of X, denoted exp(X,D), is defined to be the smallest positive integer h+k over all nonnegative integers h and k such that for each vertex v in D(2) there exists an (h,k)-walk from at least one vertex in X to v. The kth upper generalized exponent of D, F(k, D(2)) is defined to be F(k, D(2)) = max{exp(X, D(2)): |X|; = k}. We discuss upper generalized exponents of two-colored primitive extremal ministrong digraphs on n vertices, that is a two-colored digraph consisting of an (n-l)-cycle and an (n-2)-cycle. We present a lower bound for the kth upper generalized exponent that depends on n and k. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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16. Far-infrared-light shadowgraphy for high extraction efficiency of extreme ultraviolet light from a CO2-laser-generated tin plasma.
- Author
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Hiraku Matsukuma, Tatsuya Hosoda, Yosuke Suzuki, Akifumi Yogo, Tatsuya Yanagida, Takeshi Kodama, and Hiroaki Nishimura
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SHADOWGRAPH photography ,ULTRAVIOLET radiation ,PLASMA gases ,LASER pulses ,ABSORPTION coefficients - Abstract
The two-color, double-pulse method is an efficient scheme to generate extreme ultraviolet light for fabricating the next generation semiconductor microchips. In this method, a Nd:YAG laser pulse is used to expand a several-tens-of-micrometers-scale tin droplet, and a CO
2 laser pulse is subsequently directed at the expanded tin vapor after an appropriate delay time. We propose the use of shadowgraphy with a CO2 laser probe-pulse scheme to optimize the CO2 main-drive laser. The distribution of absorption coefficients is derived from the experiment, and the results are converted to a practical absorption rate for the CO2 main-drive laser. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
17. Fast ignition realization experiment with high-contrast kilo-joule peta-watt LFEX laser and strong external magnetic field.
- Author
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Shinsuke Fujioka, Yasunobu Arikawa, Sadaoki Kojima, Tomoyuki Johzaki, Hideo Nagatomo, Hiroshi Sawada, Seung Ho Lee, Takashi Shiroto, Naofumi Ohnishi, Alessio Morace, Xavier Vaisseau, Shohei Sakata, Yuki Abe, Kazuki Matsuo, King Fai Farley Law, Shota Tosaki, Akifumi Yogo, Keisuke Shigemori, Yoichiro Hironaka, and Zhe Zhang
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LARMOR radius ,PINCH effect (Physics) ,MAGNETIC fields ,ELECTROMAGNETISM ,ELECTROMAGNETIC theory - Abstract
A petawatt laser for fast ignition experiments (LFEX) laser system [N. Miyanaga et al., J. Phys. IV France 133, 81 (2006)], which is currently capable of delivering 2 kJ in a 1.5 ps pulse using 4 laser beams, has been constructed beside the GEKKO-XII laser facility for demonstrating efficient fast heating of a dense plasma up to the ignition temperature under the auspices of the Fast Ignition Realization EXperiment (FIREX) project [H. Azechi et al., Nucl. Fusion 49, 104024 (2009)]. In the FIREX experiment, a cone is attached to a spherical target containing a fuel to prevent a corona plasma from entering the path of the intense heating LFEX laser beams. The LFEX laser beams are focused at the tip of the cone to generate a relativistic electron beam (REB), which heats a dense fuel core generated by compression of a spherical deuterized plastic target induced by the GEKKO-XII laser beams. Recent studies indicate that the current heating efficiency is only 0.4%, and three requirements to achieve higher efficiency of the fast ignition (FI) scheme with the current GEKKO and LFEX systems have been identified: (i) reduction of the high energy tail of the REB; (ii) formation of a fuel core with high areal density using a limited number (twelve) of GEKKOXII laser beams as well as a limited energy (4 kJ of 0.53-μm light in a 1.3 ns pulse); (iii) guiding and focusing of the REB to the fuel core. Laser-plasma interactions in a long-scale plasma generate electrons that are too energetic to efficiently heat the fuel core. Three actions were taken to meet the first requirement. First, the intensity contrast of the foot pulses to the main pulses of the LFEX was improved to >10
9 . Second, a 5.5-mm-long cone was introduced to reduce pre-heating of the inner cone wall caused by illumination of the unconverted 1.053-μm light of implosion beam (GEKKO-XII). Third, the outside of the cone wall was coated with a 40-μm plastic layer to protect it from the pressure caused by imploding plasma. Following the above improvements, conversion of 13% of the LFEX laser energy to a low energy portion of the REB, whose slope temperature is 0.7 MeV, which is close to the ponderomotive scaling value, was achieved. To meet the second requirement, the compression of a solid spherical ball with a diameter of 200-μm to form a dense core with an areal density of ~0.07 g/cm2 was induced by a laser-driven spherically converging shock wave. Converging shock compression is more hydrodynamically stable compared to shell implosion, while a hot spot cannot be generated with a solid ball target. Solid ball compression is preferable also for compressing an external magnetic field to collimate the REB to the fuel core, due to the relatively small magnetic Reynolds number of the shock compressed region. To meet the third requirement, we have generated a strong kilo-tesla magnetic field using a laser-driven capacitor- coil target. The strength and time history of the magnetic field were characterized with proton deflectometry and a B-dot probe. Guidance of the REB using a 0.6-kT field in a planar geometry has been demonstrated at the LULI 2000 laser facility. In a realistic FI scenario, a magnetic mirror is formed between the REB generation point and the fuel core. The effects of the strong magnetic field on not only REB transport but also plasma compression were studied using numerical simulations. According to the transport calculations, the heating efficiency can be improved from 0.4% to 4% by the GEKKO and LFEX laser system by meeting the three requirements described above. This efficiency is scalable to 10% of the heating efficiency by increasing the areal density of the fuel core. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
18. Direct measurement of kilo-tesla level magnetic field generated with laser-driven capacitor-coil target by proton deflectometry.
- Author
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Law, K. F. F., Bailly-Grandvaux, M., Morace, A., Sakata, S., Matsuo, K., Kojima, S., Lee, S., Vaisseau, X., Arikawa, Y., Yogo, A., Kondo, K., Zhang, Z., Bellei, C., Santos, J. J., Fujioka, S., and Azechi, H.
- Subjects
PLASMA jets ,CAPACITOR testing ,ASTROPHYSICAL jets ,LORENTZ force ,MAGNETIC field measurements ,PROTON beams - Abstract
A kilo-tesla level, quasi-static magnetic field (B-field), which is generated with an intense laser-driven capacitor-coil target, was measured by proton deflectometry with a proper plasma shielding. Proton deflectometry is a direct and reliable method to diagnose strong, mm³-scale laser-produced B-field; however, this was not successful in the previous experiment. A target-normal-sheath-accelerated proton beam is deflected by Lorentz force in the laser-produced magnetic field with the resulting deflection pattern recorded on a radiochromic film stack. A 610630 T of B-field amplitude was inferred by comparing the experimental proton pattern with Monte-Carlo calculations. The amplitude and temporal evolutions of the laser-generated B-field were also measured by a differential magnetic probe, independently confirming the proton deflectometry measurement results. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
19. Note: A Laue crystal imager for high energy quasi-monochromatic x-ray.
- Author
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Zhang, Zhe, Nishimura, Hiroaki, Yao, Akira, Suzuki, Yosuke, Shobu, Takahisa, Yasuda, Ryo, Yogo, Akifumi, and Li, Yutong
- Subjects
HARD X-rays ,SYNCHROTRON radiation ,ELECTROMAGNETIC waves ,PARTICLE physics ,PEPTIZATION - Abstract
A newly designed transmission type x-ray Laue imager for tens of keV hard x-rays is reported. Compared with the traditional reflection type x-ray crystal imager, the transmission geometry produces a much better image quality for high energy hard x-rays. This system was assessed via a calibration experiment performed at the SPring8 synchrotron radiation facility. With a Ta x-ray fluorescer, the mono-energetic x-ray at 70 keV from the synchrotron radiation was converted to an isotropically emitted Ta K-shell source at 57.5 keV and 65 keV. A tungsten pinhole array was employed as the test object, and clear images of the pinholes with a magnification of ∼5 were acquired. These images exhibited superior quality in the dispersion plane. As an extension of this work, a slit-free full-spectral Laue imager is proposed for high resolution hard x-ray imaging. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
20. Characterization of material ablation driven by laser generated intense extreme ultraviolet light.
- Author
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Nozomi Tanaka, Masaya Masuda, Ryo Deguchi, Masakatsu Murakami, Atsushi Sunahara, Shinsuke Fujioka, Akifumi Yogo, and Hiroaki Nishimura
- Subjects
PLASMA production ,ULTRAVIOLET radiation ,HYDRODYNAMICS ,LASER pulses ,PHOTOIONIZATION - Abstract
We present a comparative study on the hydrodynamic behaviour of plasmas generated by material ablation by the irradiation of nanosecond extreme ultraviolet (EUV or XUV) or infrared laser pulses on solid samples. It was clarified that the difference in the photon energy deposition and following material heating mechanism between these two lights result in the difference in the plasma parameters and plasma expansion characteristics. Silicon plate was ablated by either focused intense EUV pulse (λ=9-25 nm, 10 ns) or laser pulse (λ=1064 nm, 10 ns), both with an intensity of ~10
9 W/cm². Both the angular distributions and energy spectra of the expanding ions revealed that the photoionized plasma generated by the EUV light differs significantly from that produced by the laser. The laser-generated plasma undergoes spherical expansion, whereas the EUV-generated plasma undergoes planar expansion in a comparatively narrow angular range. It is presumed that the EUV radiation is transmitted through the expanding plasma and directly photoionizes the samples in the solid phase, consequently forming a high-density and high-pressure plasma. Due to a steep pressure gradient along the direction of the target normal, the EUV plasma expands straightforward resulting in the narrower angular distribution observed. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
21. Stochastic regimes in the driven oscillator with a step-like nonlinearity.
- Author
-
Bulanov, S. V., Yogo, A., Esirkepov, T. Zh., Koga, J. K., Bulanov, S. S., Kondo, K., and Kando, M.
- Subjects
- *
STOCHASTIC analysis , *NONLINEAR theories , *ELECTRON energy states , *ELECTROMAGNETIC waves , *OSCILLATIONS - Abstract
A nonlinear oscillator with an abruptly inhomogeneous restoring force driven by an uniform oscillating force exhibits stochastic properties under specific resonance conditions. This behaviour elucidates the elementary mechanism of the electron energization in the strong electromagnetic wave interaction with thin targets. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
22. Radioactivity produced by a repetitive laser-driven proton beam using a shot-to-shot proton spectral measurement and a direct activation method.
- Author
-
Ogura, Koichi, Shizuma, Toshiyuki, Hayakawa, Takehito, Yogo, Akifumi, Nishiuchi, Mamiko, Orimo, Satoshi, Sagisaka, Akito, Pirozhkov, Alexander, Mori, Michiaki, Kiriyama, Hiromitsu, Kanazawa, Shuhei, Kondo, Shuji, Nakai, Yoshiki, Shimomura, Takuya, Tanoue, Manabu, Sasao, Hajime, Wakai, Daisuke, Sasao, Fumitaka, Okada, Hajime, and Kimura, Toyoaki
- Subjects
RADIOACTIVITY ,LASER beams ,PROTON beams ,NUCLEAR reactions ,GAMMA rays ,NUCLEAR cross sections ,SPECTRAL energy distribution ,DETECTORS ,SIGNAL processing - Abstract
A proton beam driven by a repetitive high-intensity-laser is utilized to induce a 7Li(p,n) 7Be nuclear reaction. The total activity of 7Be are evaluated by two different methods. The activity obtained measuring the decay gamma-rays after 1912 shots at 1 Hz is 1.7 ± 0.2 Bq. This is in good agreement with 1.6 ± 0.2 Bq evaluated from the proton energy distribution measured using a time-offlight detector and the nuclear reaction cross-sections. We conclude that the production of activity can be monitored in real time using the time-of-flight-detector placed inside a diverging proton beam coupled with a high-speed signal processing system. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
23. Electron energy transport in the thin foil driven by high contrast high intensity laser pulse.
- Author
-
Tanimoto, T., Nishiuchi, M., Mishima, Y., Kikuyama, K., Morioka, T., Morita, K., Kanasaki, M., Pirozhkov, A. S., Yogo, A., Ogura, K., Fukuda, Y., Sakaki, H., Sagisaka, A., Habara, H., Tanaka, K. A., and Kondo, K.
- Subjects
ELECTRON transport ,ENERGY transfer ,METAL foils ,LASER pulses ,ELECTRON spectroscopy ,RELATIVITY (Physics) ,TEMPERATURE effect ,MATHEMATICAL models - Abstract
The fast electron spectrum was measured for the interaction between the thin foil and the relativistic optical high field. There were two components in the electron spectrum. The higher temperature component was almost explained by the ponderomotive formula [formula]. The total electron spectrum including the lower temperature component was also explained by a simple model. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
24. Recent progress in particle acceleration from the interaction between thin-foil targets and J-KAREN laser pulses.
- Author
-
Nishiuchi, Mamiko, Pirozhkov, Alexander S., Sakaki, Hironao, Ogura, Koichi, Esirkepov, Timur Zh, Tanimoto, Tsuyoshi, Yogo, Akifumi, Hori, Toshihiko, Sagisaka, Akito, Fukuda, Yuji, Kanasaki, Masato, Kiriyama, Hiromitsu, Shimomura, Takuya, Tanoue, Manabu, Nakai, Yoshiki, Sasao, Hajime, Sasao, Fumitaka, Kanazawa, Shuhei, Kondo, Shuji, and Matsumoto, Yoshihiro
- Subjects
PARTICLE acceleration ,LASER pulses ,PROTON beams ,STAINLESS steel ,METAL foils ,ANGULAR distribution (Nuclear physics) ,PLASMA gases ,ELECTRIC fields - Abstract
From the interaction between the high-contrast (∼more than 1010) 130 TW Ti:sapphire laser pulse and Stainless Steel-2.5 um-thick tape target, proton beam with energies up to 23 MeV with the conversion efficiency of ∼1% is obtained. After plasma mirror installation for contrast improvement, from the interaction between the 30 TW laser pulse and thin-foil target installed on the target holder with the hole whose shape is associated with the design of the well-known Wehnelt electrode of electron-gun, a 7 MeV intense proton beam is controlled dynamically and energy selected by the self-induced quasi-static electric field on the target holder. From the highly divergent beam having continuous spectrum, which are the typical features of the laser-driven proton beams from the interactions between the short-pulse laser and solid target, the spatial distribution of 7 MeV proton bunch is well manipulated to be focused to an small spots with an angular distribution of ∼10 mrad. The number of protons included in the bunch is >106. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
25. Radiobiological study by using laser-driven proton beams.
- Author
-
Yogo, A., Sato, K., Nishikino, M., Mori, M., Teshima, T., Numasaki, H., Murakami, M., Demizu, Y., Akagi, S., Nagayama, S., Ogura, K., Sagisaka, A., Orimo, S., Nishiuchi, M., Pirozhkov, A. S., Ikegami, M., Tampo, M., Sakaki, H., Suzuki, M., and Daito, I.
- Subjects
- *
PROTON beams , *ION bombardment , *RADIOBIOLOGY , *PARTICLE accelerators , *CELLULAR pathology - Abstract
Particle acceleration driven by high-intensity laser systems is widely attracting interest as a potential alternative to conventional ion acceleration, including ion accelerator applications to tumor therapy. Recent works have shown that a high intensity laser pulse can produce single proton bunches of a high current and a short pulse duration. This unique feature of laser-ion acceleration can lead to progress in the development of novel ion sources. However, there has been no experimental study of the biological effects of laser-driven ion beams. We describe in this report the first demonstrated irradiation effect of laser-accelerated protons on human lung cancer cells. In-vitro A549 cells are irradiated with a proton dose of 20 Gy, resulting in a distinct formation of γ-H2AX foci as an indicator of DNA double-strand breaks. This is a pioneering result that points to future investigations of the radiobiological effects of laser-driven ion beams. The laser-driven ion beam is apotential excitation source for time-resolved determination of hydroxyl (OH) radical yield, which will explore relationship between the fundamental chemical reactions of radiation effects and consequent biological processes. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
26. Acceleration of negative ions by Coulomb implosion mechanism.
- Author
-
Nakamura, T., Fukuda, Y., Yogo, A., Tampo, M., Kando, M., Hayashi, Y., Kameshima, T., Pirozhkov, A. S., Esirkepov, T. Zh., Pikuz, T. A., Faenov, A. Ya., Daido, H., and Bulanov, S. V.
- Subjects
ANIONS ,LASER beams ,SIMULATION methods & models ,LASER-plasma interactions ,PROPERTIES of matter - Abstract
Generation of high energy negative ions by laser-plasma interaction is studied theoretically and numerically. New acceleration process called Coulomb implosion mechanism is proposed, which explains efficient acceleration of negative ions from laser-plasmas. The model is confirmed by using 2-dimenstional Particle-in-Cell simulations. Experimental evidence of negative ion acceleration from cluster target is also presented. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
27. Laser driven proton beam for the applications: toward ultra-high intensity & short pulse proton beam.
- Author
-
Nishiuchi, M., Daido, H., Daito, I., Ikegami, M., Mori, M., Orimo, S., Ogura, K., Sagisaka, A., Yogo, A., Pirozhkov, A. S., Sugiyama, H., Kiriyama, H., Okada, H., Kanazawa, S., Kondo, S., Shimomura, T., Tanoue, M., Nakai, Y., Sasao, H., and Wakai, D.
- Subjects
PROTON beams ,PROTON accelerators ,MAGNETICS ,SIMULATION methods & models ,MAGNETS - Abstract
As a benchmark experiment to realize a novel and compact laser driven proton accelerator whose significant features are high number density in a short pulse width (∼ns), 2.4 MeV laser driven proton beam is stably focused at 1 Hz repetition rate by using a pair of permanent quadrupole magnets (PMQs) with large apertures whose diameters and field strengths are 3.5 cm and 55 T/m for the first and 2.3 cm and 60 T/m for the second magnets, respectively. The proton beam has been focused to a focal spot of 3×8 mm
2 in horizontal and vertical direction (full width at half maximum) at 650∼mm from the source, which is well reproduced by the simulation. The further optimization of the focusing system will sure to pave a way to the novel proton accelerator with which we can investigate the physics appeared in the short time scale as well as that in a high energy density matter, oncology, astrophysics, and so on. [ABSTRACT FROM AUTHOR]- Published
- 2009
- Full Text
- View/download PDF
28. Femtosecond-Laser-Driven Cluster-Based Plasma Source for High-Resolution Ionography.
- Author
-
Faenov, A. Ya., Pikuz, T. A., Fukuda, Y., Kando, M., Kotaki, H., Homma, T., Kawase, K., Kameshima, T., Pirozhkov, A., Yogo, A., Tampo, M., Mori, M., Sakaki, H., Hayashi, Y., Nakamura, T., Pikuz, Jr., S. A., Kartashev, V., Skobelev, I. Yu., Gasilov, S. V., and Giulietti, A.
- Subjects
FEMTOSECOND lasers ,POLYPROPYLENE ,THERMOPLASTICS ,LASER beams ,MULTIPLY charged ions - Abstract
The intense isotropic source of multicharged ions, with energy above 300 keV, was produced by femtosecond Ti:Sa laser pulses irradiation (intensity of ∼4×10
17 W/cm2 ) of the He and CO2 gases mixture expanded in supersonic jet. High contrast ionography images have been obtained for 2000 dpi metal mesh, 1 μm polypropylene and 100 nm Zr foils, as well as for different biological objects. Images were recorded on 1 mm thick CR-39 ion detector placed in contact with back surface of the imaged samples, at the distances 140–160 mm from the plasma source. The obtained spatial resolution of the image was ∼600 nm. A 100 nm object thickness difference was resolved very well for both Zr and polymer foils. The multicharged ion energy for Carbon and Oxygen ions passing through the 1 μm polypropylene foil is estimated to give the energy of more than 300 keV. An almost equal number of ions were measured with total number of about 108 per shot at a different direction from plasma source. Easy production of different sub-MeV ions in wide space angle, recognizes femtosecond-laser-driven-cluster-based plasma as a well-suited bright source for novel type of submicron ionography to image different media, including nanofoils, membranes, and other low-contrast objects. [ABSTRACT FROM AUTHOR]- Published
- 2009
- Full Text
- View/download PDF
29. Phase Rotation Scheme To Combine an RF Technique With Laser-Plasma Interaction For Real Applications Of Laser-Produced Ions.
- Author
-
Noda, Akira, Iwashita, Yoshihisa, Souda, Hikaru, Tongu, Hiromu, Wakita, Akihisa, Daido, Hiroyuki, Ikegami, Masahiro, Kiriyama, Hiromitsu, Mori, Michiaki, Nishiuchi, Mamiko, Ogura, Koichi, Orimo, Satoshi, Pirozhkov, Alexander, Sagisaka, Akito, Yogo, Akifumi, and Shirai, Toshiyuki
- Subjects
LASER-plasma interactions ,LASER beams ,ELECTRIC fields ,ELECTROMAGNETIC fields ,ELECTROLYSIS - Abstract
A phase rotation scheme of laser-produced ions from a solid target by the application of a synchronized RF electric voltage with a pulsed laser has been experimentally investigated with the use of a 100 TW laser, J-KAREN at JAEA, KPSI. Up to now, energy peaks of up to around 2.0 MeV have been created with a FWHM of 2.6% with good reproducibility using a two-gap resonator of a quarter wave length with the same frequency as the source laser (∼80 MHz). It is also found that the position of the peak can be well controlled by adjusting the relative phase between the RF electric field and the laser, which is very promising for real applications of such laser-produced protons. In order to also apply such a phase rotation system for higher energy protons (<200 MeV), a scheme to use a small linear accelerator (LINAC) with multi-gaps is proposed as a phase rotator. With multi-gap structure, alternating focusing between longitudinal and transverse degrees of freedoms can be realized. From the point of compactness and realizing a small focused spot, however, a scheme combining separate quadrupole magnets just before and after the RF cavity excited with the Wideröe mode, might be more effective. The scheme presented here will realize laser-produced ions (protons) with good reproducibility by combining with RF technology. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
30. Ion acceleration in the interaction of short pulse laser radiation with the cluster-gas target.
- Author
-
Fukuda, Y., Faenov, A. Ya., Tampo, M., Pikuz, T. A., Nakamura, T., Kando, M., Hayashi, Y., Yogo, A., Sakaki, H., Kameshima, T., Pirozhkov, A. S., Ogura, K., Mori, M., Esirkepov, T. Zh., Boldarev, A. S., Gasilov, V. A., Magunov, A. I., Kodama, R., Bolton, P. R., and Kato, Y.
- Subjects
ACCELERATION (Mechanics) ,IONS ,LASER beams ,HADRONS ,PARTICLES (Nuclear physics) - Abstract
We demonstrate generation of 10–20 MeV/u ions with a compact 4 TW laser using a gas target mixed with submicron clusters, corresponding to tenfold increase in the ion energies compared to previous experiments with solid targets. It is inferred that the high energy ions are generated due to formation of a strong dipole vortex structure. The demonstrated method has a potential to construct compact and high repetition rate ion sources for hadron therapy and other applications. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
31. Laser ion acceleration by a near-critical density target.
- Author
-
Yogo, A., Daido, H., Bulanov, S. V., Esirkepov, T. Zh., Nemoto, K., Oishi, Y., Nayuki, T., Fujii, T., Ogura, K., Orimo, S., Sagisaka, A., Ma, J.-L., Mori, M., Nishiuchi, M., Pirozhkov, A. S., Nakamura, S., Noda, A., and Nagatomo, H.
- Subjects
- *
PROTONS , *ULTRASHORT laser pulses , *LASER beams , *IRRADIATION , *POLYIMIDES , *PLASMA gases , *METAL foils - Abstract
Protons having energies up to 3.8 MeV are experimentally generated by the p-polarized, 45 fs, ∼1019 W/cm2 laser pulse interacting with a near-critical plasma cloud produced by the irradiation of the amplified spontaneous emission (ASE) pedestal at an intensity of ∼1013 W/cm2 onto a 7.5-μm-thick polyimide foil target. The emission angle of the high-energy protons is shifted away from the target normal toward the laser-propagation direction of 45°. The mechanism which explains the proton generation from the near-critical plasma cloud is discussed using the two-dimensional (2D) particle-in-cell (PIC) simulation. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
32. Femtosecond laser driven high-flux highly collimated MeV-proton beam.
- Author
-
Nishiuchi, M., Daido, H., Yogo, A., Orimo, S., Ogura, K., Ma, J., Sagisaka, A., Mori, M., Pirozhkov, A. S., Kiriyama, H., Bulanov, S. V., Esirkepov, T. Zh., Choi, Il Woo, Yu, Tae Jun, Shung, Jae Hee, Jeong, Tae Moon, Kim, Hyung Taek, Hong, Kyung-Ham, Noh, Young-Chul, and Ko, Do-Kyeong
- Subjects
LASER beams ,PROTON beams ,FEMTOCHEMISTRY ,PHOTOSENSITIVE polyimides ,TITANIUM ,ULTRASHORT laser pulses ,NEUTRON flux - Abstract
Highlly collimated energetic protons whose energies are up to 4 MeV are generated by an intense femtosecond Titanium Sappheire laser pulse interacting with a 7.5, 12.5, and 25 μm-thick Polyimide tape target and 5 μm-thick copper target. We find no clear difference on the proton spectra from 7.5, 12.5, and 25 μm Polyimide tape target. The highest conversion efficiency from laser energy into protons of ∼3% is observed with a 7.5 μm thick Polyimide target. The quality of the proton beam is good enough to obtain a clear projection image of a mesh having 10 μm line and space structure, installed into the passage of the beam. We obtain clear vertical lines on the proton intensity profiles from the copper target, which are considered to be transferred from the surface of the copper target. From it, we can restrict the size of the proton emitting region to be ∼20 μm. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
33. High-energy proton generation from thin-foil targets with a high-intensity ultra-short pulse laser.
- Author
-
Sagisaka, Akito, Daido, Hiroyuki, Yogo, Akifumi, Ogura, Koichi, Orimo, Satoshi, Ma, Jinglong, Mori, Michiaki, Nishiuchi, Mamiko, Pirozhkov, Alexander S., Bulanov, Sergei V., Esirkepov, Timur Zh., Oishi, Yuji, Nayuki, Takuya, Fujii, Takashi, and Nemoto, Koshichi
- Subjects
PROTON scattering ,HIGH power lasers ,PROTON beams ,LASER plasmas ,PHOTOSENSITIVE polyimides ,QUASIELASTIC light scattering - Abstract
We observe the proton signals with thin-foil polyimide and copper targets with a high-intensity Ti:sapphire laser pulse. High-energy protons with the maximum energy of 2.3 MeV for 7.5 μm thick polyimide target and 1.2 MeV for 3 μm thick copper target are generated at the laser intensity of ∼1×10
19 W/cm2 under preformed plasma condition. [ABSTRACT FROM AUTHOR]- Published
- 2008
- Full Text
- View/download PDF
34. Development of Laser-Driven Proton and Electron Sources Using APRI 100-TW Ti:Sapphire Laser System.
- Author
-
Choi, I. W., Hafz, N., Jeong, T. M., Kim, H. T., Kim, C. M., Yu, T. J., Sung, J. H., Hong, K.-H., Lee, S. K., Noh, Y.-C., Ko, D.-K., Lee, J., Orimo, S., Yogo, A., Sagisaka, A., Ogura, K., Mori, M., Li, Z., Ma, J., and Pirozhkov, A. S.
- Subjects
ULTRASHORT laser pulses ,ELECTRON beams ,PROTON beams ,ACCELERATION (Mechanics) ,LASER-plasma interactions - Abstract
At the Advanced Photonics Research Institute (APRI) in Korea, we have a Ti:sapphire laser system which delivers laser pulses of 100-TW peak power and 32-fs pulse duration at the repetition rate of 10 Hz. This laser facility is being used to develop compact laser-driven proton and electron sources. Energetic protons are produced by irradiating the laser pulse on a thin foil target made of copper and polyimide via the target normal sheath acceleration. Proton beam with maximum energy of up to 4 MeV was generated from a polyimide target, and showed high energy conversion efficiency from laser to proton energy. Generation of high-energy electron beams by the laser wakefield acceleration was performed by focusing the laser pulses onto a 4 mm-long He-gas jet. Quasi-monoenergetic electron beam with peak energy of 45 MeV and maximum energy of 130 MeV was produced. The quality and characteristics of electron beams are strongly dependent on the laser-plasma interaction length which depends on focal length of the focusing optics. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
35. MeV quasi-mono-energetic proton beam created by a combination of a laser-plasma ion accelerator and synchronous rf cavity.
- Author
-
Ikegami, M., Nakamura, S., Iwashita, Y., Shirai, T., Souda, H., Tajima, Y., Tanabe, M., Tongu, H., Itoh, H., Shintaku, H., Yamazaki, A., Daido, H., Yogo, A., Orimo, S., Mori, M., Nishiuchi, M., Ogura, K., Pirozhkov, A., Ma, J., and Kiriyama, H.
- Subjects
PROTON beams ,RADIO frequency ,ELECTRIC fields ,LASER plasmas ,SPECTRUM analysis - Abstract
MeV quasi-mono-energetic proton beam is produced by a combination of a synchronous radio frequency (rf) electric field and laser-plasma ion acceleration. The experiment was carried out at the Kansai Photon Science Institute, JAEA, using the Ti:Sapphire laser system called J-KAREN. The proton beam is emitted normal to the rear surface of the thin polyimide target of the thickness 7.5 μm irradiated at peak intensity of 4×10
18 W/cm2 . The energy spread is compressed from 100% to less than 11% at FWHM by the rf field. The focusing and defocusing effect of the transverse direction is also observed. These are also studied by a Monte Carlo simulation. The relation between the transverse focusing and the energy spectrum of the phase-rotated beam is systematically shown by the simulation. [ABSTRACT FROM AUTHOR]- Published
- 2008
- Full Text
- View/download PDF
36. Development of the Fast FE Method for Welding Deformation.
- Author
-
Yogo, Yasuhiro, Goto, Noritake, Iwata, Noritoshi, Nakanishi, Koukichi, and Yagishita, Shuntaro
- Subjects
- *
FINITE element method , *WELDING , *MANUFACTURING processes , *NUMERICAL analysis , *IRONWORK , *SOLDER & soldering , *HEAT flux , *HEAT transfer - Abstract
We propose a fast finite element method for the prediction of welding deformation. To decrease the calculation time, this method allows the shell element to be used with the modeling for welding phenomena such as the heat source and joining. For the sake of further time savings, this method includes discrete thermal mechanically coupled analysis, which controls the frequency of mechanical calculations. Reasonable agreement between experimental results and calculation results has been obtained using simulated automotive parts with a short calculation time. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
37. Numerical Prediction of Springback Shape of Severely Bent Sheet Metal.
- Author
-
Iwata, Noritoshi, Tsutamori, Hideo, Niihara, Masatomo, Ishikura, Hiroshi, Umezu, Yasuyoshi, Murata, Atsunobu, and Yogo, Yasuhiro
- Subjects
STRESS concentration ,SHEET metal work ,NUMERICAL analysis ,DEFORMATIONS (Mechanics) ,PROPERTIES of matter ,PHYSICAL sciences - Abstract
In the sheet metal forming simulation, the shell element widely used is assumed as a plane stress state based on the Mindlin-Reissner theory. Numerical prediction with the conventional shell element is not accurate when the bending radius is small compared to the sheet thickness. The main reason is because the strain and stress formulation of the conventional shell element does not fit the actual phenomenon. In order to predict precisely the springback of a bent sheet with a severe bend, a measurement method for through-thickness strain has been proposed. The strain was formulated based on measurement results and calculation results from solid element. Through-thickness stress distribution was formulated based on the equilibrium. The proposed shell element based on the formulations was newly introduced into the FEM code. The accuracy of this method’s prediction of the springback shape of two bent processes has been confirmed. As a result, it was found that the springback shape even in severe bending can be predicted with high accuracy. Moreover, the calculation time in the proposed shell element is about twice that in the conventional shell element, and has been shortened to about 1/20 compared to a solid element. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
38. Nuclear moment studies with polarized radioactive nuclear beams.
- Author
-
Asahi, K., Sakai, K., Ogawa, H., Ueno, H., Kobayashi, Y., Yoshimi, A., Miyoshi, H., Yogo, K., Goto, A., Suga, T., Imai, H., Watanabe, Y. X., Yoneda, K., Fukuda, N., Aoi, N., Schmidt-Ott, W.-D., Neyens, G., Teughels, S., Yoshida, A., and Kubo, T.
- Subjects
ROTATIONAL motion ,POLARIZATION (Nuclear physics) ,NUCLEAR fragmentation - Abstract
Beams of spin-polarized radioactive nuclei are produced in the projectile fragmentation reaction induced by intermediate-energy heavy ion beams, and are used for the measurement of magnetic dipole and electric quadrupole moments of nuclei in the regions far from stability. In this paper, after remarking the mechanism of fragment polarization and the experimental techniques to make use of it, we discuss the recent results obtained for the electromagnetic moments of light neutron-rich nuclei at RIKEN. Analyses of the observed magnetic moments in terms of shell models show intriguing results which imply that some of the basic nuclear properties, such as the order in energy of the single-particle orbits, the pairing energy between the excess neutrons, and the effective g[sub s]-factor for a halo nucleon, tend to alter as the degree of neutron excess increases. Also, the measured electric quadrupole moments reveal remarkable quenching of the E2 effective charge in nuclei with large N/Z ratios. [ABSTRACT FROM AUTHOR]
- Published
- 2001
39. Novel spin maser mechanism studied for high-precision measurement of neutron electric dipole moment.
- Author
-
Yoshimi, A., Asahi, K., Yogo, K., Sakai, K., Ogawa, H., Suzuki, T., and Nagakura, M.
- Subjects
MASERS ,ROTATIONAL motion ,DIPOLE moments - Abstract
We propose a new scheme of nuclear spin maser and have performed the experimental and theoretical analyses for its operation, aiming at the significant improvement in sensitivity of neutron electric dipole moment (EDM). The proposed spin-masing scheme incorporates an artificial feedback mechanism, and is applicable to extremely low density systems of spins such as a bottled ensemble of UCNs. Its operation was experimentally demonstrated by using a spin-polarized [sup 129]Xe gas as a model substance. The frequency analysis suggests that a frequency precision allowing a neutron EDM search with a sensitivity of 10[sup -28] ecm level is attainable by this maser scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2001
40. Effective charge anomaly in neutron-rich nuclei revealed from spin-polarized RI beam experiments.
- Author
-
Ogawa, H., Sakai, K., Ueno, H., Suzuki, T., Asahi, K., Miyoshi, H., Nagakura, M., Yogo, K., Goto, A., Suga, T., Honda, T., Imai, N., Watanabe, Y. X., Yoneda, K., Yoshimi, A., Fukuda, N., Aoi, N., Kobayashi, Y., Schmidt-Ott, W.-D., and Neyens, G.
- Subjects
QUADRUPOLE moments ,POLARIZED beams (Nuclear physics) ,FRAGMENTATION reactions - Abstract
The electric quadrupole moment of [sup 17]B was measured by means of spin polarized fragment beams produced by the projectile fragmentation reaction. The experimental quadrupole moment of [sup 17]B was very close to that of neutron p-shell closed nucleus [sup 13]B. This result indicates that the neutron effective charge for [sup 17]B is considerably smaller than the value commonly used in the sd-shell region. [ABSTRACT FROM AUTHOR]
- Published
- 2001
41. Measurements of electron-induced neutrons as a tool for determination of electron temperature of fast electrons in the task of optimization laser- produced plasma ions acceleration.
- Author
-
Sakaki, H., Nishiuchi, M., Maeda, S., Sagisaka, A., Pirozhkov, A. S., Pikuz, T., Faenov, A., Ogura, K., Fukami, T., Matsukawa, K., Kanasaki, M., Fukuda, Y., Yogo, A., Esirkepov, T., Kiriyama, H., Shimomura, T., Nakai, Y., Tanoue, M., Torimoto, K., and Okamoto, M.
- Subjects
LASER-plasma interactions ,LASER beams ,PARTICLE beams ,ION beams ,PHYSICS instruments ,ELECTRONS - Abstract
High intensity laser-plasma interaction has attracted considerable interest for a number of years. The laser-plasma interaction is accompanied by generation of various charged particle beams, such as high-energy proton and ions with high charge to mass ratio (Q/M; same as multi-charged ions). Results of simultaneous novel measurements of electron-induced photonuclear neutrons (photoneutron), which are a diagnostic of the laser-plasma interaction, are proposed to use for optimization of the laser-plasma ion generation. The proposed method is demonstrated by the laser irradiation with the intensity of 1 x 10
21 W/cm² on the metal foil target. The photoneutrons are measured by using NE213 liquid scintillation detectors. Heavy-ion signal is registered with the CR-39 track detector simultaneously. The measured signals of the electron-induced photoneutrons are well reproduced by using the Particle and Heavy Ion Transport code System. The results obtained provide useful approach for analyzing the various laser based ion beams. [ABSTRACT FROM AUTHOR]- Published
- 2014
- Full Text
- View/download PDF
42. Quantitative measurement of hard x-ray spectra for high intensity laser produced plasma.
- Author
-
Zhang, Z., Nishimura, H., Namimoto, T., Fujioka, S., Arikawa, Y., Nishikino, M., Kawachi, T., Sagisaka, A., Hosoda, H., Orimo, S., Ogura, K., Pirozhkov, A., Yogo, A., Okano, Y., Kiriyama, H., Kondo, K., Ohshima, S., and Azechi, H.
- Subjects
SPECTRUM analysis ,X-rays ,CRYSTALS ,DETECTORS ,PHOSPHORS - Abstract
X-ray line spectra ranging from 17 to 77 keV were quantitatively measured with a Laue spectrometer, composed of a cylindrically curved crystal and a detector. Either a visible CCD detector coupled with a CsI phosphor screen or an imaging plate can be chosen, depending on the signal intensities and exposure times. The absolute sensitivity of the spectrometer system was calibrated using pre-characterized laser-produced x-ray sources and radioisotopes. The integrated reflectivity for the crystal is in good agreement with predictions by an open code for x-ray diffraction. The energy transfer efficiency from incident laser beams to hot electrons, as the energy transfer agency for specific x-ray line emissions, is derived as a consequence of this work. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
43. Quasi-monochromatic pencil beam of laser-driven protons generated using a conical cavity target holder.
- Author
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Nishiuchi, M., Pirozhkov, A. S., Sakaki, H., Ogura, K., Zh. Esirkepov, T., Tanimoto, T., Kanasaki, M., Yogo, A., Hori, T., Sagisaka, A., Fukuda, Y., Matsumoto, Y., Entani, S., Sakai, S., Brenner, C. M., Neely, D., Yamauchi, T., Bulanov, S. V., and Kondo, K.
- Subjects
PROTON beams ,MONOCHROMATORS ,THICKNESS measurement ,LASER beams ,ELECTRIC currents ,ELECTRON accelerators - Abstract
A 7 MeV proton beam collimated to 16 mrad containing more than 10
6 particles is experimentally demonstrated by focusing a 2 J, 60 fs pulse of a Ti:sapphire laser onto targets of different materials and thicknesses placed in a millimeter scale conical holder. The electric potential induced on the target holder by laser-driven electrons accelerates and dynamically controls a portion of a divergent quasi-thermal proton beam originated from the target, producing a quasi-monoenergetic 'pencil' beam. [ABSTRACT FROM AUTHOR]- Published
- 2012
- Full Text
- View/download PDF
44. High energy negative ion generation by Coulomb implosion mechanism.
- Author
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Nakamura, T., Fukuda, Y., Yogo, A., Tampo, M., Kando, M., Hayashi, Y., Kameshima, T., Pirozhkov, A. S., Esirkepov, T. Zh., Pikuz, T. A., Faenov, A. Ya., Daido, H., and Bulanov, S. V.
- Subjects
ANIONS ,COULOMB potential ,LASER plasmas ,ACCELERATION (Mechanics) ,ULTRASHORT laser pulses - Abstract
Generation of high energy negative ions from laser plasmas by Coulomb implosion mechanism is investigated. When clusters or underdense plasmas are irradiated by an intense laser pulse, positive ions are accelerated inside the clusters or in the self-focusing channel by the Coulomb explosion. This could lead to the acceleration of negative ions toward target center. The maximum energy of negative ions is typically several times lower than that of positive ions. A theoretical description and corresponding particle-in-cell simulations of Coulomb implosion mechanism are presented. We show the evidence of the negative ion acceleration observed in our experiments using high intensity laser pulse and the cluster-gas targets. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
45. Ion spectrometer composed of time-of-flight and Thomson parabola spectrometers for simultaneous characterization of laser-driven ions.
- Author
-
Choi, I. W., Kim, C. M., Sung, J. H., Yu, T. J., Lee, S. K., Kim, I. J., Jin, Y.-Y., Jeong, T. M., Hafz, N., Pae, K. H., Noh, Y.-C., Ko, D.-K., Yogo, A., Pirozhkov, A. S., Ogura, K., Orimo, S., Sagisaka, A., Nishiuchi, M., Daito, I., and Oishi, Y.
- Subjects
SPECTROMETERS ,IONS ,SPECTRUM analysis ,ION sources ,ENGINEERING instruments - Abstract
An ion spectrometer, composed of a time-of-flight spectrometer (TOFS) and a Thomson parabola spectrometer (TPS), has been developed to measure energy spectra and to analyze species of laser-driven ions. Two spectrometers can be operated simultaneously, thereby facilitate to compare the independently measured data and to combine advantages of each spectrometer. Real-time and shot-to-shot characterizations have been possible with the TOFS, and species of ions can be analyzed with the TPS. The two spectrometers show very good agreement of maximum proton energy even for a single laser shot. The composite ion spectrometer can provide two complementary spectra measured by TOFS with a large solid angle and TPS with a small one for the same ion source, which are useful to estimate precise total ion number and to investigate fine structure of energy spectrum at high energy depending on the detection position and solid angle. Advantage and comparison to other online measurement system, such as the TPS equipped with microchannel plate, are discussed in terms of overlay of ion species, high-repetition rate operation, detection solid angle, and detector characteristics of imaging plate. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
46. Efficient production of a collimated MeV proton beam from a polyimide target driven by an intense femtosecond laser pulse.
- Author
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Nishiuchi, M., Daido, H., Yogo, A., Orimo, S., Ogura, K., Ma, J., Sagisaka, A., Mori, M., Pirozhkov, A. S., Kiriyama, H., Bulanov, S. V., Esirkepov, T. Zh., Choi, I. W., Kim, C. M., Jeong, T. M., Yu, T. J., Sung, J. H., Lee, S. K., Hafz, N., and Pae, K. H.
- Subjects
PROTON beams ,FEMTOCHEMISTRY ,LASER beams ,POLYIMIDES ,PHYSICS - Abstract
High-flux energetic protons whose maximum energies are up to 4 MeV are generated by an intense femtosecond titanium:sapphire laser pulse interacting with 7.5, 12.5, and 25 μm thick polyimide tape targets. Laser pulse with an energy of 1.7 J and with a duration of 34 fs is focused with an f/3.4 parabolic mirror giving an intensity of 3×10
19 W cm-2 . The main pulse to amplified spontaneous emission (ASE) intensity contrast ratio is 2.5×107 . The conversion efficiency from the laser energy into the proton kinetic energies is achieved to be ∼3%, which is comparable to or even higher than those achieved in the previous works; using nanometer-thick targets, in combination with the short-pulse lasers that have almost the same pulse width and the intensity but different main pulse to ASE intensity contrast of ∼1010 [Neely et al., Appl. Phys. Lett. 89, 021502 (2006)], in which the authors claim that the main mechanism is target normal sheath acceleration; or using the 7.5 μm thick polyimide target, in combination with the short-pulse laser, which has almost the same pulse width and the intensity, but the main pulse to ASE intensity contrast ratio was controlled to be 2.5×105 [Yogo et al., Phys. Rev. E 77, 016401 (2008)], in which the authors claim the efficient acceleration by the mechanism of the underdense plasma model. The contrast ratio of the present experiment is in between these two experiments. The possible mechanism of this regime is discussed. [ABSTRACT FROM AUTHOR]- Published
- 2008
- Full Text
- View/download PDF
47. Laser prepulse dependency of proton-energy distributions in ultraintense laser-foil interactions with an online time-of-flight technique.
- Author
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Yogo, Akifumi, Daido, Hiroyuki, Fukumi, Atsushi, Zhong Li, Ogura, Koichi, Sagisaka, Akito, Pirozhkov, Alexander S., Nakamura, Shu, Iwashita, Yoshihisa, Shirai, Toshiyuki, Noda, Akira, Oishi, Yuji, Nayuki, Takuya, Fujii, Takashi, Nemoto, Koshichi, Il Woo Choi, Hee Sung, Jae, Do-Kyeong Ko, Jongmin Lee, and Kaneda, Minoru
- Subjects
- *
MASS spectrometers , *TIME-of-flight mass spectrometry , *IRRADIATION , *PLASMA lasers , *PLASMA radiation - Abstract
Fast protons are observed by a newly developed online time-of-flight spectrometer, which provides shot-to-shot proton-energy distributions immediately after the irradiation of a laser pulse having an intensity of ∼1018 W/cm2 onto a 5-μm-thick copper foil. The maximum proton energy is found to increase when the intensity of a fs prepulse arriving 9 ns before the main pulse increases from 1014 to 1015 W/cm2. Interferometric measurement indicates that the preformed-plasma expansion at the front surface is smaller than 15 μm, which corresponds to the spatial resolution of the diagnostics. This sharp gradient of the plasma has the beneficial effect of increasing the absorption efficiency of the main-pulse energy, resulting in the increase in the proton energy. This is supported by the result that the x-ray intensity from the laser plasma clearly increases with the prepulse intensity. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
48. Extreme ultraviolet diagnostics of preformed plasma in laser-driven proton acceleration experiments.
- Author
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Ragozin, Eugene N., Pirozhkov, Alexander S., Yogo, Akifumi, Ma, Jinglong, Ogura, Koichi, Orimo, Satoshi, Sagisaka, Akito, Mori, Michiaki, Li, Zhong, Nishiuchi, Mamiko, and Daido, Hiroyuki
- Subjects
PROTONS ,PROTON accelerators ,IRRADIATION ,PHOTODIODES ,SEMICONDUCTOR diodes ,X-rays ,ULTRAVIOLET radiation ,LASERS ,LASER plasmas - Abstract
Proton acceleration experiments involving a 5 μm thick Ti foil target irradiation are carried out with the femtosecond Ti:sapphire laser JLITE-X. The plasma emission at 13.5 nm is recorded employing concave multilayer mirrors, which image the front- and rear-side plasmas onto the sensitive surfaces of a fast x-ray photodiode and a backside-illuminated charge coupled device. Online time-of-flight fast-particle measurements are performed simultaneously with the extreme ultraviolet (XUV) measurements. A strong correlation is observed between the energetic proton signal and the spatiotemporal behavior of the XUV plasma emission. In particular, the longer duration of the prepulse-produced XUV plasma emission indicates a lowering of the maximum proton energy. This allows using the XUV emission for the diagnostics of the high-intensity laser–solid-target interaction. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
49. Measurement of relative biological effectiveness of protons in human cancer cells using a laser-driven quasimonoenergetic proton beamline.
- Author
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Yogo, A., Maeda, T., Hori, T., Sakaki, H., Ogura, K., Nishiuchi, M., Sagisaka, A., Kiriyama, H., Okada, H., Kanazawa, S., Shimomura, T., Nakai, Y., Tanoue, M., Sasao, F., Bolton, P. R., Murakami, M., Nomura, T., Kawanishi, S., and Kondo, K.
- Subjects
- *
PROTONS , *CANCER cells , *MAGNETIC dipoles , *SALIVARY gland tumors , *DRUG dosage , *ENERGY transfer , *ION bombardment , *POLYIMIDES , *TIME-of-flight mass spectrometry - Abstract
Human cancer cells are irradiated by laser-driven quasimonoenergetic protons. Laser pulse intensities at the 5×1019 W/cm2 level provide the source and acceleration field for protons that are subsequently transported by four energy-selective dipole magnets. The transport line delivers 2.25 MeV protons with an energy spread of 0.66 MeV and a bunch duration of 20 ns. The survival fraction of in vitro cells from a human salivary gland tumor is measured with a colony formation assay following proton irradiation at dose levels of up to 8 Gy, for which the single bunch dose rate is 1×107 Gy/s and the effective dose rate is 0.2 Gy/s for 1 Hz repetition of irradiation. Relative biological effectiveness at the 10% survival fraction is measured to be 1.20±0.11 using protons with a linear energy transfer of 17.1 keV/μm. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
50. Submicron ionography of nanostructures using a femtosecond-laser-driven-cluster-based source.
- Author
-
Faenov, A. Ya., Pikuz, T. A., Fukuda, Y., Kando, M., Kotaki, H., Homma, T., Kawase, K., Kameshima, T., Pirozhkov, A., Yogo, A., Tampo, M., Mori, M., Sakaki, H., Hayashi, Y., Nakamura, T., Pikuz, S. A., Skobelev, I. Yu., Gasilov, S. V., Giulietti, A., and Cecchetti, C. A.
- Subjects
NANOSTRUCTURES ,ISOTROPY subgroups ,OXYGEN ,CARBON ,POLYMERS ,IRRADIATION - Abstract
An intense isotropic source of multicharged carbon and oxygen ions with energy above 300 keV and particle number >10
8 per shot was obtained by femtosecond Ti:Sa laser irradiation of submicron clusters. The source was employed for high-contrast contact ionography images with 600 nm spatial resolution. A variation in object thickness of 100 nm was well resolved for both Zr and polymer foils. [ABSTRACT FROM AUTHOR]- Published
- 2009
- Full Text
- View/download PDF
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