We have demonstrated the measurements of attenuation constant of a multi-mode fiber (300μm core diameter and 1km
length) at 1070nm. The observed attenuation constant was below 0.7dB/km. The laser power of 5kW was coupled into
the 1km fiber at 1070nm. The overall transmittance was 85 %. We observed the first Raman stokes in the transmitted
laser spectrum.
We demonstrated concrete cutting with a 4kW fiber laser at 1070nm. The demonstrated slab thickness was 100mm.
This technique can be extended to thick concrete slabs more than 1m without laser power increasing.
Chemical oxygen-iodine laser (COIL) has a great potential for applications such as decommissioning and dismantlement (D&D) of nuclear reactor, rock destruction and removal and extraction of a natural resource (Methane hydrate) because of the unique characteristics such as power scalability, high optical beam quality and optical fiber beam. Five-kilowatt Chemical oxygen-iodine laser (COIL) test facility has been developed. The chemical efficiency of 27% has been demonstrated with a moderate beam quality for optical fiber coupling. Our research program contains conventional/ejector-COIL scheme, Jet-SOG/Mist-SOG optimization, fiber delivery and long-term operation.
The transmission of chemical oxygen-iodine laser (COIL) emission through several kinds of multimode quartz optical fiber is measured in order to explore the applicability of COILs for the extraction of natural resources. The minimum transmission loss through these fibers is 0.64 dB/km, and high-power transmission for a distance of kilometers is shown to be feasible. Laser emission at an average input power of 1 kW is successfully transmitted through a multimode optical fiber for a distance of 1 km with an efficiency of 80%.
Chemical oxygen-iodine laser (COIL) has a great potential for applications such as decommissioning and dismantlement (D&D) of nuclear reactor, rock destruction and removal and extraction of a natural resource (Methane hydrate) because of the unique characteristics such as power scalability, high optical beam quality and optical fiber beam. Five-kilowatt Chemical oxygen-iodine laser (COIL) test facility has been developed. The chemical efficiency of 27% has been demonstrated with a moderate beam quality for optical fiber coupling. Our research program contains conventional/ejector-COIL scheme, Jet-SOG/Mist-SOG optimization, fiber delivery and long-term operation.
Analysis of heat release into operative gas of Chemical Oxygen Iodine Laser (COIL) is discussed. Pooling reaction of oxygen molecules in the excited state, the iodine dissociation process and the interaction of them with water vapor release energy of in the excited state oxygen molecules as heat energy. As results of heat release in the plenum, a rise of the total pressure as a rise of the total temperature is observed, and in the supersonic region a rise of static pressure and a decrease of total pressure as a rise of total temperature are observed. By following our analysis technique regarding pressure data of three different nozzles, the evaluations such as energy loss in a duct from a Singlet delta Oxygen
Generator (SOG) and the number of dissipated oxygen molecules for the iodine dissociation can be estimated.
Miki Pulley has pursued the development of a prototype COIL module for field and industrial applications since its transfer from Tokai University in 2000. The test module has already been constructed in our laboratory. The current status of the development is presented. The achieved chemical efficiency was 17.5% at the chlorine flow rate of 13.2mol/min. The corresponding laser power was 3.5kW.
KEYWORDS: Diffusers, Throat, Iodine, Chemical oxygen iodine lasers, Laser resonators, Chemical analysis, Chemical reactions, Molecules, Laser development, Chemical lasers
Optimization of iodine injection scheme was conducted in Miki Pulley Co., Ltd. using CFD approach. Variation of the mixing speed as a function of an I2 jet penetration depth, nozzle expansion ratio, and I2 injection point are analyzed. It was found that the inherent geometry of our nozzle and I2 injector affects the I2 mixing process. Influence of a backpressure to the cavity flow condition was also investigated in order to estimate the pressure recovery capability of our diffuser. The normal shock based diffuser efficiency for Mach=2.7 flow was 54.5%.
Laser medium parameters of multi-kW grid nozzle supersonic Chemical Oxygen Iodine Laser (COIL) were experimentally studied. Small-signal gain (SSG) diagnostics was done by a narrow line width tunable laser by scanning 1 GHz range around (2P1/2 ) - (2P3/2) spin-orbit transition line of atomic iodine. SSG was investigated as a function of Mach number and gas flow rates. Modeling of gain for different flow conditions was done as well. Multi-kW COIL device was recently developed in Miki Pulley Co., Ltd. (Japan) and has 37.5 cm length of active medium.
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