All issues
Volume 49, Issue 1
Special Issue on Applications of Shock Wave Induced by High Power Lasers
Displaying 1-14 of 14 articles from this issue
- |<
- <
- 1
- >
- >|
Special Issue on Applications of Shock Wave Induced by High Power Lasers
-
Takasumi TANABE2021 Volume 49 Issue 1 Pages 3-
Published: 2021
Released on J-STAGE: February 03, 2024
JOURNAL FREE ACCESSDownload PDF (256K)
Special Issue
Laser Review
-
Keisuke SHIGEMORI2021 Volume 49 Issue 1 Pages 5-
Published: 2021
Released on J-STAGE: February 03, 2024
JOURNAL FREE ACCESSThis article describes brief overview for the special issue on “Applications of Shock Wave Induced by High Power Lasers”. The applications by use of laser-induced shock wave compression have been developed with developing “ultra-high average power lasers”. The special issue includes laser developments, shock wave physics, applications to laser peening, and related progress on this topic.View full abstractDownload PDF (216K) -
Takashi SEKINE, Takashi KURITA,, Norio KURITA, Toshiyuki KAWASHIMA2021 Volume 49 Issue 1 Pages 6-
Published: 2021
Released on J-STAGE: April 01, 2024
JOURNAL FREE ACCESSIn recent years, the development of diode-pumped 100-J class laser has strongly advanced in Europe, United States and Japan. In Europe, a 100 J × 10 Hz laser has been installed at an X-ray free electron laser facility for academic use. The application of a 100-J class laser has also started in Japan in an industrial field as a material processing platform to construct a laser-processing database, which is used in the construction of a cyber-physical system for laser processing. We developed a diode-pumped cryogenically cooled Yb:YAG ceramics laser as a material-processing platform. Our laser has demonstrated over 100-J output energy with a compact and simple system. This paper reviews the world’s trends of 100-J class diode-pumped lasers and describes the development of a cryogenic-helium gas cooled Yb:YAG ceramics laser amplifier. Finally, the current progress on the development of a 250-J class laser amplifier toward 1-kJ laser technologies is presented.View full abstractDownload PDF (629K) -
Yoichiro HIRONAKA, Eisuke MIURA, Kohei MIYANISHI, Norimasa OZAKI, Keis ...2021 Volume 49 Issue 1 Pages 11-
Published: 2021
Released on J-STAGE: April 01, 2024
JOURNAL FREE ACCESSWith the recent development in the output power of lasers, processing using high power lasers has come to be used instead of conventional techniques. This article introduces nanosecond laser peening mechanisms. Compared with the prior technique, laser peening has the feature of being able to add a deep residual stress field to the material in spite of less surface deformation, which can be explained by a dislocation density model using a microscopic local stress field due to shock waves. Since the microscopic local stress field shows a strong correlation with the shock wave, the interference of the spatial shock wave affects the residual stress field distribution. This article clarifies such physical properties and describes the possibility of peening using a high-power laser.View full abstractDownload PDF (1791K) -
Kohei MIYANISHI2021 Volume 49 Issue 1 Pages 17-
Published: 2021
Released on J-STAGE: April 01, 2024
JOURNAL FREE ACCESSThis article reviews our experimental investigation of the phase transformation process of 304 austenitic stainless steel (SUS304) in the laser peening process. An optical laser pump–X-ray free-electron laser probe in-situ time-resolved X-ray diffraction measurement reveals the formation process of α ′-martensite from γ -austenite of SUS304 under shock compression and release, which occur during the laser peening process. The result indicates that fast tensile strain rate deformation, arising from shock pressure release waves, drives a considerable amount of the transformation to transient ε -martensite from γ - austenite, where the transient ε -martensite acts as an intermediate phase of the transformation to α ′-martensite.View full abstractDownload PDF (690K) -
Miho TSUYAMA2021 Volume 49 Issue 1 Pages 22-
Published: 2021
Released on J-STAGE: April 01, 2024
JOURNAL FREE ACCESSOur studies on the improvement of processing efficiency for laser peening are presented in this paper. Although laser peening is a useful technique for the surface treatment of metals, its uses are limited to special applications, e.g., airplane parts, nuclear power plants, etc. For applications for general industries, the processing efficiency must be improved through systematic studies that identify the numerous parameters that affect laser peening. As an example, this paper introduces the effect of acoustic impedance control in the plasma confinement layer on laser peening. Three solutions, sucrose, glycerol, and ethylene glycol, have been used as the plasma confinement layer to improve the processing efficiency of laser peening.View full abstractDownload PDF (1082K) -
Tomokazu SANO2021 Volume 49 Issue 1 Pages 28-
Published: 2021
Released on J-STAGE: April 01, 2024
JOURNAL FREE ACCESSWe have successfully performed femtosecond laser peening on a 2024 aluminum alloy, which was not covered with any sacrificial overlays such as a protective coating, nor using water as a plasma confinement medium during the peening treatment, in air. The femtosecond laser peening process has a great potential to be applied in various fields where conventional peening methods can not be used, as this process can be performed under ambient conditions without the use of a sacrificial overlay on the material.View full abstractDownload PDF (1569K) -
Takuo OKUCHI2021 Volume 49 Issue 1 Pages 35-
Published: 2021
Released on J-STAGE: April 01, 2024
JOURNAL FREE ACCESSShock-compressed states of planetary materials have been analyzed using high-power lasers. Here we review recent results of these experiments to compress planetary ices and minerals. Planetary ices made of hydrogen, oxygen, carbon and nitrogen are the most abundant solid occurring in the universe. Their particles had coalesced together to develop into icy giant planets such as Uranus and Neptune when the solar system was formed. At high pressure and temperature conditions relevant to the interiors of these planets, these ices were proved to become a good electronic conductor, which is the best-possible rationale of strong magnetic fields originating from insides of these planets. Using high-power lasers, such exotic properties of planetary ices have been revealed. In addition, shock-compressed states of planetary minerals (represented by forsterite olivine, Mg2SiO4) were successfully analyzed; for this purpose, X-ray free electron laser is combined with the high-power laser for ultrafast analysis of shock-ompressed crystal structures.View full abstractDownload PDF (659K) -
Keisuke SHIGEMORI2021 Volume 49 Issue 1 Pages 40-
Published: 2021
Released on J-STAGE: April 01, 2024
JOURNAL FREE ACCESSShock ignition (SI) scheme of inertial confinement fusion targets is considered as a promising scheme to reduce the required drive laser energy for ignition. On the SI scheme, a spherical shell target is compressed by relatively low intensity laser pulse irradiation, and hot spot is ignited by converging shock waves by high intensity laser pulse called “spike pulse”. The strong shock by the spike pulse should be over 300 Mbar (=30 TPa). The key physics to produce such ultrahigh pressure is the contribution of hot electrons generated by parametric instabilities. The hot electron generation, transport, and their effects on shock wave parameters in various experimental conditions were experimentally explored. This review focuses on recent experimental study on the effect of ultrahigh pressure generation produced by hot electrons.View full abstractDownload PDF (1054K)
Laser Original
-
Yuki KABEYA2021 Volume 49 Issue 1 Pages 45-
Published: 2021
Released on J-STAGE: April 01, 2024
JOURNAL FREE ACCESSLaser peening (LP) is one of several surface modification techniques which can provide compressive residual stress to a metal surface and enhance the fatigue strength. It is applied to strengthen a turbine blade of an aircraft engine and repair a core shroud in a nuclear power plant. In general, the effect of LP is evaluated by measuring the compressive residual stress in a point on the treated area. However, it is required to consider the uniformity of the compressive residual stress distribution on the top surface, suppressing generation of fatigue cracks. Furthermore, prediction of a compressive residual stress distribution is also important to optimize laser process parameters. In this paper, we propose and demonstrate a prediction method of the residual stress distribution by using laser intensity distribution and material properties. The effectiveness of the proposed method is verified by comparison of predicted and measured distributions.View full abstractDownload PDF (831K) -
Masahiro YOSHIIKE2021 Volume 49 Issue 1 Pages 50-
Published: 2021
Released on J-STAGE: April 01, 2024
JOURNAL FREE ACCESSWe investigated the effects of laser peening on various aluminum alloys which are usually used for various industrial fields to estimate desirable laser parameters. Seven typical aluminum alloys were used as samples: 1050, 2017, 3003, 4032, 5052, 6061, and 7075. The laser intensity and coverage, which is the number of laser pulses irradiated per unit, were varied during our laser peening experiments. We found that the surface hardness due to the work hardening and the compressive residual stress depend mainly on the coverage in aluminum alloys. A laser intensity around 1.0 GW/cm 2 with coverage around 2000% is desirable for the efficient laser peening of aluminum alloys.View full abstractDownload PDF (1135K) -
Yuhei UMEDA2021 Volume 49 Issue 1 Pages 56-
Published: 2021
Released on J-STAGE: April 01, 2024
JOURNAL FREE ACCESSCalcite, which is a universal mineral in meteorites and rocky planet surfaces, might be a source of CO and/or CO2 gas components caused by impact processes. In this study, we conducted Hugoniot measurements and in-situ XRD (x-ray diffraction) observations of calcite during shock processes in order to understand shock responses and shock-induced reactions under planetary impact conditions. We newly obtained experimental data of shocked calcite above 100 GPa using a high-power laser shock technique. Our temperature data indicated a large difference from the previous theoretical model as well as some state changes along the Hugoniot. The result of the in-situ XRD observations using an X-ray Free Electron Laser (XFEL) shows the polycrystallization and the melting of calcite during the compressed and released state. Such shock-induced reactions of calcite may affect the estimation of the total energy, the thermal history and the degassing chemical species during planetary impacts.View full abstractDownload PDF (863K)
Regular Paper
-
Hidetsugu YOSHIDA2021 Volume 49 Issue 1 Pages 61-
Published: 2021
Released on J-STAGE: April 01, 2024
JOURNAL FREE ACCESSA large diameter Faraday isolator for kW class average laser systems was developed using a 53-mm diameter TGG (Tb3Ga5O12) ceramic. The wavefront distortion of TGG ceramic was 0.1 ~ 0.2λ . The maximum magnetic field provided by a permanent magnet was 1.4 ~ 1.5 T. A 53-mm diameter Faraday isolator was demonstrated using a TGG compensation for thermal induced depolarization. The compensated depolarization Faraday rotator is over 4% at incident laser power of over 900 W. This Faraday rotator is scalable to large apertures for kW class (few 10 J pulse at 100 Hz repetition rate) average- power laser systems.View full abstractDownload PDF (1072K) -
Kento OOSAWA2021 Volume 49 Issue 1 Pages 67-
Published: 2021
Released on J-STAGE: April 01, 2024
JOURNAL FREE ACCESSA laser space solar power system (L-SSPS) supplies solar power in space to the earth by the laser beams at the giga-watt level in total. The amplifier of this system is required to output a large diameter beam and have good thermal resistant. Since an active-mirror amplifier meets these requirements, we calculated the 8-pass amplification of an active-mirror amplifier for continuous optical loss. In space, the laser medium must operate at high temperature. We assumed the temperature of the laser medium was 400 K for achieve higher more than 80% extraction efficiency. We chose the medium thickness was 0.3 cm and the number of slabs were 187, 20.21% laser efficiency was achieved. The optimized laser output strength was 3.1 kW/cm 2 per unit. We analyzed the effect of the optical wave front distortion caused by the pump distribution and determined the optimum overall amplifier design.View full abstractDownload PDF (1720K)
- |<
- <
- 1
- >
- >|