Researches in Thermal Laser for a System of Cascading Energy Conversion into Light, Motive Energy and Thermal Energy

2003 Fiscal Year Final Research Report Summary

• Project/Area Number: 14205111
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 化学工学一般
• Research Institution: Nagoya University
• Principal Investigator: HASATANI Masanobu Nagoya University, Faculty of Engineering, Professor, 工学研究科, 教授 (50021788)
• Co-Investigator(Kenkyū-buntansha): DAGUCHI Seiichi Nagoya University, Faculty of Engineering, Lector, 工学研究科, 講師 (50283411) ; WATANABE Fujio Nagoya University, Faculty of Engineering, Assistant of Research, 工学研究科, 助手 (70109312) ; KOBAYASHI Noriyuki Nagoya University, Center for Integrated Research in Science and Engineering, Associate Professor, 理工科学総合研究センター, 助教授 (90242883) ; WADA Akio JASCO Co., 1^<st> Development Dept., Researcher, 第一技術部, 研究員 ; KOBAYASHI Jun Nagoya University, Faculty of Engineering, Assistant of Research, 工学研究科, 助手 (60314035)
• Project Period (FY): 2002 – 2003
• Keywords: Thermal laser / Cascading energy conversion / Population inversion / Super sonic fluid / O_2-enriched combustion

Research Abstract

A cascading energy-conversion-system which transforms a high-temperature and high-pressure energy generated by a combustion into three modes energy is proposed. These energy modes are laser amplification, motive energy and thermal one. In this research, the required conditions are extracted to establish the three modes energy-conversion-system and preliminary works in the amplification of the thermal laser have been investigated. The problems in the system are focused into two points. Because of installation of a gas turbine behind the laser equipment, requirements of the combustion temperature and the pressure for an amplification of the infrared laser caused by a population inversion of CO_2 are completely dissimilar with the conditions of general gas dynamic laser. Other one is decrease of CO_2 molecule in population inversion. This is why an increase of H_2O fraction in a laser medium causes deactivation of exited CO_2 molecules although mixtures of CO_2, N_2, H_2O are generated co ntinuously with a combustion reaction of hydrocarbons. Experimental and theoretical researches in an identification of CO_2 population inversion required for the infrared laser amplification were investigated. Results achieved are shown as follows. The gas flows quickly through a nozzle at supersonic speed, which forces the translational temperature to drop to a lower value. In the results, the vibrational temperature of the lower level being close to the translational temperature, while the vibrational temperature of the upper level is close to pre-expansion temperature. An amplification of 10.6 μm infrared light is investigated experimentally with the laser medium which is produced from combustion of CH_4 in O_2-enriched field. O_2-enriched combustion is adopted as a method that produces high temperature-high pressure gas easily. Plus gains are identified under adequate combustion conditions. It is considered that the deactivation of the upper level CO_2 is reduced because vibration energy level of O_2 (=1556 cm^<-1>) is close to that of H_2O (1595 cm^<-1>).