When a barium plasma was suddenly produced between parallel plate electrodes and an upper plate electrode with a higher potential, the ion extraction was investigated in comparison with characteristics of the usual parallel plate electrode configuration. The parameter dependencies of ion extraction time by an external electric field, measured under a variety of experimental conditions, led to the conclusion that the ion extraction time can be expressed as the product of exponents of the applied voltage, plasma width, and ion density as well as the parallel plate electrodes. This scaling relation estimates the ion extraction time with an accuracy of 15% for a given parameter set. Comparison of the scaling relations for the new electrode concept with a highly biased upper plate electrode and the parallel plate electrodes showed that the former improves the ion extraction time by a maximum factor of 2.6.
In a sodium-cooled fast reactor (SFR), liquid sodium is used as a heat transfer fluid because of its excellent heat transport capability. One of the design basis accidents of the SFR is the water leakage into the liquid sodium flow by a breach of heat transfer tubes in a steam generator. Therefore the study on sodium-water chemical reactions is of paramount importance for safety reasons. This study aims to clarify the sodium-water reaction mechanisms using laser diagnostics. The sodium-water, sodium-oxygen and sodium-hydrogen counter-flow reactions were measured using laser diagnostics such as Raman, absorption and photo-fragmentation spectroscopies. The measurement results show that the main product of the sodium-water reaction is NaOH. The sodium-water reaction rate is slower than that of the sodium-oxygen reaction and hydrogen does not react noticeably with sodium.
The applications of laser-induced breakdown spectroscopy (LIBS) have been widely expanding from the utilization on Earth to outer space, and the expected LIBS performance has created a lot of expectations for the coming digital transformation age. There are several conventional methods to compete with LIBS as an elemental analysis method. Inductively coupled plasma atomic emission spectroscopy, inductively coupled plasma-mass spectrometry, and X-ray fluorescence analysis are typical methods that have been applied to similar fields as LIBS applications. The hybrid technology of LIBS and other methods has been one of the prospective solutions for the future development of LIBS. Raman spectroscopy, laser-induced fluorescence, and absorption spectroscopy can be combined with LIBS to simultaneously analyze the molecular information. Optical coherence tomography (OCT) can be a good partner with LIBS. OCT is an interferometric technology that detects a backscattered light from an object using low interference laser light.
Recent years have already seen tighter regulation on harmful substances such as NOx, CO, and particles. Considering the above situation, it is important to monitor controlling factors of engine systems in order to improve efficiencies of their operations. In car engines an increasing concern in environmental issues such as air pollution, global warming and petroleum depletion has helped drive researches into various ways. Laser diagnostics has been applied to measure species concentration in the actual industrial fields. However there are several challenges to proceed in applying laser diagnostics to practical application. Especially stability of the measurement system is one of the most difficult issues. The purpose of this research is the development of a prompt measurement technique which can be applicable to various engine conditions. The tunable diode laser absorption spectroscopy(TDLAS) using the hollow fiber has been developed to satisfy above requirements. By using a hollow fiber, misalignment of an optical axis and vulnerability of measurement environment such as vibration can be greatly reduced with sensitive and fast response features. It was demonstrated that this method can be applicable to measure gas compositions in engine exhaust with a range of millisecond response time. A sensitive method using tunable UV diode laser absorption spectroscopy was also discussed to detect NOx in exhausts.
Flux Switching Integrated Starter-Generator (FSISG) system was employed to solve the global environmental problems and energy issues. The output performance is vital to the application of FSISG system in Hybrid Electric Vehicle (HEV). In order to investigate the performance of FSISG system, a design methodology of FSISG, a dual-mode control circuit and the relevant control methods were discussed and studied in this paper. Then the experimental investigations were carried out based on the drivers which were manufactured according to the designed dual-mode control circuit. The results demonstrate the excellent performance of FSISG system with dual-mode control circuit. In generating mode, the output voltages of FSISG show a high precision and a well stability in wide rotational speed range. In starting mode, FSISG system shows a well dynamic performance under the different load conditions and load variation condition.
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