Interaction of millisecond kW-class laser pulses with metals and metal oxides; Fundamentals of processing

Daido, Hiroyuki*; Yamada, Tomonori

ILT-APR-34; ILT 2023 Nempo (Internet), p.1 - 5, 2023/07

The decommissioning of Fukushima and the contribution to reconstruction have become national issues. The authors participated in the "Analysis of fine particles generated by laser processing and development of nuclide identification method" (represented by Professor Shuichi Hasegawa of the University of Tokyo), which was adopted as one of the JAEA's publicly solicited projects for this purpose, from FY 2018 to FY 2021 as a subcontractor, The authors conducted research on the observation, evaluation and analysis of the interaction between lasers and various laser-irradiated targets. This report outlines the results of the research in which the authors took part. In the experiments, laser irradiation was carried out on test specimens set up in an irradiation chamber, and shadowgraphs were taken using a high-speed camera and a He-Ne laser. As an example of the experimental results, shadowgraphs of metal (stainless steel) and metal oxide (zirconia), irradiation traces after laser irradiation, and the relationship between laser irradiation power and jet mass are shown, and the interaction between the laser and the metal or metal oxide is discussed. The results will not only contribute to the decommissioning technology of the Fukushima Daiichi NPP, but also to laser processing technology and laser interaction research.

Preparation of Computational Science Simulation Code SPLICE for Laser Manufacturing Process; Research activities on FY2019

Muramatsu, Toshiharu

JAEA-Research 2019-008, 111 Pages, 2019/11

JAEA-Research-2019-008.pdf:8.64MB

A general-purpose three-dimensional thermohydraulics numerical simulation code SPLICE (residual Stress control using Phenomenological modeling for Laser welding repair process In Computational Environment) was designed to deal with gas-liquid-solid consolidated incompressible viscous flows with a phase change process in various laser applications. Main features of the SPLICE code are as follows: (1) A multi-scale model is used to simulate complicated phenomena, such as welding to solidification of metal materials, thermal and mechanical interactions among gas, liquid and solid phases, etc., (2) SPLICE code is applicable for the evaluation of welding, cutting, piercing, coating, additive manufacturing, etc. and (3) A graphic user interface (GUI) is prepared for users to easy utilization of the SPLICE code. This report describes the details of the mathematics, physics, numerics, sample applications of the SPLICE code.

Computational science simulation of laser material processing and provision of their irradiation conditions

Muramatsu, Toshiharu

KANRIN, 68, p.14 - 18, 2016/09

no abstracts in English

Demonstration of heat resistant fiber Bragg grating sensors based on femtosecond laser processing for vibration monitoring and temperature change

Nishimura, Akihiko; Takenaka, Yusuke*; Furuyama, Takehiro*; Shimomura, Takuya; Terada, Takaya; Daido, Hiroyuki

Journal of Laser Micro/Nanoengineering, 9(3), p.221 - 224, 2014/11

https://doi.org/10.2961/jlmn.2014.03.0007

Heat resistant FBG sensors were developed by femtosecond laser processing to apply them to high temperature operated piping system of nuclear power plants. The FBG sensor was installed on the surface of a steel blade and a vibration test was conducted to detect the resonant vibration frequency of the vibrating blade. The FBG sensor had the heatproof performance at 600C. A frequency stabilized sensing system using a tunable laser was tested for structural health monitoring in daily operation of nuclear power plants. The FBG sensor was installed on the surface of a steel blade for vibration induced strain measurements. Welding, brazing, soldering and noble metal powder adhesive were discussed for molding the FBG sensors.

Molecular dynamics analysis of laser shock phenomena due to Gaussian beam irradiation

Fukumoto, Ichiro; Omura, Etsuji*

Seimitsu Kogakkai-Shi, 67(6), p.916 - 921, 2001/06

https://doi.org/10.2493/jjspe.67.916

no abstracts in English

Non-thermal effect on femtosecond laser ablation of polymers extracted from oscillation of time-resolved reflectivity

Kumada, Takayuki; Akagi, Hiroshi; Itakura, Ryuji; Otobe, Tomohito; Yokoyama, Atsushi

no journal, , 

It has been proposed that not only thermal but also non-thermal effect plays an important role on femtosecond laser ablation. In this study, we develop a high-sensitivity time-resolved reflectivity measurement system to study the non-thermal effect on the femtosecond laser ablation of polymers.

Research and development on ray irradiation effects of a multi functional laser processing head for fuel debris removal

Muramatsu, Toshiharu; Nakamura, Masaki; Abe, Hiroshi*

no journal, , 

no abstracts in English

Picosecond pulse laser processing of carbon fiber reinforced resin

Kosuge, Atsushi

no journal, , 

Carbon fiber reinforced plastic is a resin-based composite material reinforced with carbon fiber, which is a high-performance fiber having features such as light weight, high strength, and high rigidity. CFRTP using a thermoplastic resin has a short molding time and is excellent in economy, and the thermoplastic resin melts when heat is applied, so that it can be recycled. On the other hand, CFRP and CFRTP are known as difficult-to-process materials that are difficult to process, and in laser processing, a heat-affected region is generated in which the resin evaporates and carbon fibers are exposed when irradiated with a laser. Since there is a concern that this heat-affected zone will reduce the strength of CFRP and CFRTP, it has become an important issue in recent years to find processing conditions that keep this heat-affected zone small. Search for conditions.

Study on application of laser spectroscopic techniques to laser processing

Miyabe, Masabumi

no journal, , 

We have studied the applicability of spectroscopic technique for obtaining process information needed for laser decommissioning and other various laser processing techniques. When a material is irradiated with intense laser pulses, atomic species eject from the surface which absorbing the light energy via inverse Bremsstrahlung process and laser plasma grows rapidly. Thus various properties of the generated laser plasma strongly depend on the duration of the laser irradiation. Although previous studies have reported differences in emission characteristics between Nd:YAG lasers with about 10 ns-pulse and long-pulse lasers with about 100 ns-pulse, little is known about the emission and/or absorption characteristics of the plasma produced through the irradiation of longer than 10 ms duration, which is common in current laser processing. In this study, we investigated the emission characteristics of the laser plasma produced in atmospheric air using a QCW (Quasi Continuous Wave) fiber laser. As a result, it was found that the emission intensity of oxide molecules is enhanced. Also, only for zirconia and gadolinia targets, strong emission lines of atomic species were observed. From the images recorded during laser ablation process, it was observed that the sputtered materials were burned while floating in the air and this might contribute to strong emission signal of atomic species. This study demonstrated the possibility of applying emission spectroscopy to laser processing to evaluate elemental composition of the processed materials.