Iodine isotopes can be used as tracers to study geological, marine and environmental processes and to monitor nuclear environmental safety. In view of the urgent need for the detection of iodine molecular isotopes in the field of environmental monitoring, it is urgent to carry out on-line monitoring of high sensitivity and high spectral resolution iodine isotopes. In this paper, aiming at the problem of the theoretical simulation of iodine molecular isotope spectrum, inversion of isotopic hyperfine spectral parameters, generation and identification of hyperfine spectral signals, some key techniques, such as Frank-Condon factor calculation, iodine molecular spectrum fitting, iodine molecular isotope measurement based on absorption spectrum and excitation fluorescence spectrum, are solved. The absorption spectra of iodine isotope molecules are theoretically simulated, which provides a theoretical reference for isotope discrimination based on spectra. A detection system based on absorption spectrum and Laser-induced iodine isotope fluorescence spectrum was established. The 127I2 absorption spectrum was measured by using 635 nm grating feedback ECDL (External-Cavity Diode Laser, ECDL), and the detection sensitivity was 1.2×1013 m-3. The 127I2 excitation fluorescence detection was realized by using 532 nm YAG laser with fiber seed injection locking, and the detection sensitivity was 5.8×1013 m-3. The results provide theoretical basis and technical support for the on-line rapid detection of iodine molecular isotopes based on spectra. Keywords: Iodine Molecular Isotopes; Absorption Spectrum; Laser Induced Fluorescence Spectroscopy; Frank-Condon
The study of underwater shock waves based on high-power laser is of great significance for understanding the interaction laws between lasers and matter in liquid environments, and it shows broad application potential in fields such as underwater detection and communication, and hydraulic mechanical design. By solving the problems of underwater environment construction and effective deposition of laser energy, this paper develops a target that can produce an underwater shock wave similar to that of point explosion based on numerical simulation. In addition, the established schlieren diagnostic system with the capability to adjust the diagnostic moment arbitrarily, can acquire four underwater shock wave evolution images in a single shot experiment, and as well as the wavefront travel time and pressure of shock wave. The research shall provide technical support for revealing the evolution laws of underwater shock waves.
The time-resolved measurement of gas components in the impact vibration environment such as combustion and explosion is of great significance for understanding the internal state and reaction process. In order to realize simultaneous detection of various gas components under impact vibration conditions, a method based on shock-resistant multi-reflection cavity is proposed to enhance spontaneous Raman scattering. The measurement system is divided into two parts: host subsystem and detection subsystem, which are connected by optical fiber. The host subsystem is far away from the impact site, while the detection subsystem is located at the measuring point, which can effectively improve the impact resistance by curing components and increasing shock absorption. At the same time, by means of signal enhancement, the measurement system can realize second-order time resolution and reliable measurement of gas components in strong impact vibration environment such as explosion. At the same time, by means of signal enhancement, the measurement system can realize second-order time resolution and reliable measurement of gas components in strong impact vibration environment such as explosion.
In order to improve extraction ability of the two-dimensional HTV grid experiment data and achieve rich flow field velocimetry data. In this paper, a two-dimensional grid extraction method combining cross ponits and grid lines is proposed. A template indirect correlation method was used to extract the position of cross ponits. Based on the vector position information of cross ponits, two-dimensional inversion of convective field velocity is achieved by using the method of skeleton extraction with directional template. This method not only can extend the inversion data, but also can be used in the scramjet combustion flow field, that the relative uncertainty of calculation speed is optimized from 0.8% to 0.17%.
In view of the surface temperature distribution and temperature rise measurement demand of metal target irradiated by high power laser, the thermosensitive phosphor surface temperature measurement technology was studied. The principle of two-color temperature measurement was introduced. After solving the key technologies of optical system optimization design, temperature distribution inversion calculation and high precision calibration, a compact thermosensitive phosphor surface temperature measuring system was developed. The temperature measurement range from room temperature to 1500 K, the space measurement range was greater than that of diameter 50mm, and the spatial resolution was better than 0.5mm. The thermosensitive phosphor surface temperature measurement technique was used to measure the surface temperature distribution and temperature rise of stainless steel targets irradiated by high power laser, and the results were compared with the results of thermocouple and numerical simulation. It is proved that the surface temperature measurement system can realize the measurement of surface temperature field distribution of high power laser irradiated target, and has high temperature measurement precision.
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