Laser-induced breakdown spectroscopy (LIBS) is a promising technology for nuclear safeguard because of the advantages of rapid analysis, in situ and real-time detection. The potential application of LIBS is simulatively investigated for continuous uranium emission monitoring during the nuclear accident. The aerosol containing UOx is generated with laser ablation to simulate the uranium emission in laboratory. The laser induced plasma emission in the aerosol has been continuously analyzed with a spectroscopy. The characteristic spectral lines of uranium have been clearly identified. The intensity variation of uranium spectral lines agrees well with UOx particles emission and sedimentation process in aerosol. The potential of LIBS is demonstrated for emergency and continuous emission monitor in nuclear accidents.
Raman spectroscopy technology is a spectral analysis technology based on Raman effect. With this technology, the molecular structure information can be identified and analyzed quickly, nondestructively and effectively, and it has high spectral specificity. Raman spectroscopy technology can provide the mineral components information of lunar soil samples, which is of great significance for lunar surface exploration and future resource utilization. In this paper, a 785nm Raman spectroscopy detection system was set up, and used to detect and identify phosphate components with different doping concentrations in various types of earth soils, which provided data support for further analysis of lunar samples.
Ultraviolet ultra-short pulse laser has incomparable advantages in strong field physics and fast ignition of inertial confinement nuclear fusion. In addition to the short wavelength and strong focusing ability, UV laser has a larger critical density and is closer to the over-dense fuel target region, thus simplifies all the process relates to the energy transport. Based on the I-λ 2 scaling law, ultraviolet laser is enough to produce hot electrons with the temperature required for fast ignition. Meanwhile, excimer laser has unique advantages in amplifying ultra-short pulses. In order to increase the laser energy irradiating on the target, the amplifier with larger energy cross section and higher energy extraction capacity are required. In this paper, a method of beam combination amplification of ultraviolet ultrashort pulse laser in a discharge-pumped excimer laser amplifier has been explored by conjugated polarization, and the feasibility of applying this technique to excimer laser is verified.
Nuclear aerosol simulant generated in laboratory plays a unique role for the development of in-situ monitoring technology of nuclear facility emission. To simulate the emission of the trace uranium aerosol, an aerosol generator based on laser ablation was set up and tested experimentally. It is shown that the concentration of aerosol particles has a linear relationship in the range of 36.28 μg/m3 to 277.13 μg/m3 while the laser intensity keeps above 7.6×106 W/cm2 . The aerosol particle size distribution is stable, while the most particles are inhalable particles based on the measurement of an aerosol spectrometer. The composition is verified with a laser induced plasma spectroscopy. Several spectral lines of uranium have been clearly identified. It is demonstrated that aerosols generated based on laser ablation can simulate nuclear facilities emission effectively. The method will be used in further work to develop direct radioactive aerosol monitoring technology.
With the deepening of globalization, security inspection has gradually become a necessary means in many occasions. Therefore, rapid and accurate identification of components in the opaque shielding material, without destroying the outer packaging, has become a necessary detection method. Spatially offset Raman spectroscopy (SORS) , as a new Raman spectroscopy technology, can meet such demands. In this paper, the SORS of NaNO3 aqueous solution contained in opaque PTFE vessel has been obtained, using a self-built SORS detection system. In addition, some important parameters such as offset distance and detection concentration has been also studied experimentally.
Defense and security applications often require definitive and non-destructive testing or identification of samples to enable testers to make effective decisions and preserve potential evidence. Raman spectroscopy has consistently demonstrated its effectiveness as an analytical technique in defense research and applications without interfering with sample integrity. Aiming at the fact that Raman spectroscopy is limited to detect sample composition within the near surface layer or transparent medium, Rutherford Appleton Laboratory proposed the spatial offset Raman spectroscopy. This technique can effectively suppress the powerful Raman and fluorescent signal interference from the surface substance, and realize the composition detection under the opaque diffuse scattering medium material of a few mm or cm. In this paper, we have detected and analyzed the spatially offset Raman spectroscopy of sodium nitrate, sodium sulphate and their mixture powder.
As a new type of conventional Raman spectroscopy(CRS) technology, spatially offset Raman spectroscopy(SORS) can acquire subsurface information of the multi-layered materials and realize the detection of concealed materials in nonmetallic opaque and translucent containers. In this paper, the spectrum of NaNO3 powder in a red opaque plastic bottle and a brown translucent glass bottle were detected with a 785nm SORS detection system. According to comparison and analysis, the Raman signal and fluorescence of the surface opaque HDPE container and the surface translucent glass container were suppressed by SORS. The subsurface concealed NaNO3 Raman spectrum peak was detected successfully.
In order to further improve the supervision of food safety, the research of rapid inspection technology for food additives with package, which can identify the ingredients of additives quickly and accurately without destroying, has become an urgent need for social development. Spatially offset Raman spectroscopy (SORS), as a derivative of new Raman spectroscopy technology, can further suppress Raman scattering and fluorescence of surface samples, and solve the problem of subsurface sample detection. SORS mainly utilizes the lateral scattering of photons generated by excitation light in multi-layered samples. By controlling the spatial offset (▵S) between the collection point and the incident point, it can realize rapid, accurate and non-destructive detection of the food additives covered by the opaque/semi-transparent medium. This work established an optical detection system based on SORS technology. Sodium nitrite and sodium benzoate samples were placed in PTFE containers instead of packaging, and the best spectral intensities were obtained by changing the offset distance ▵S. Compared with conventional Raman spectroscopy (CRS), the relative intensity of SORS spectra is significantly increased, and the spectra of food additives can be distinguished efficiently.
As a new Raman spectroscopy technology, Spatially Offset Raman Spectroscopy (SORS) can realize the detection of bilayer-and even multilayer-compositions nondestructively and non-invasively, providing the possibility of vivo biological diagnosis. In this paper, the detection of CO32- and PO43- covered by PTFE was realized, which are the main mineral components of bone tissues.
Spatially Offset Raman Spectroscopy (SORS) is a new type of Raman Spectroscopy technology, which can detect the medium concealed in the opaque or sub-transparent material fast and nondestructively. The article summarized Spatially Offset Raman Spectroscopy`s international and domestic study and application progress on contraband detecting, medical science (bone ingredient, cancer diagnose etc.), agricultural products, historical relic identification etc. and stated the technology would become an effective measurement which had wide application prospect.
A single-shot transient-grating frequency-resolved optical gating (TG-FROG) device was set up to measure UV ultrashort pulse laser with pulse duration within 10ps.The performance of the device was demonstrated by experimental data measured on discharge-pumped KrF laser which is operated in 10Hz repeated frequency mode,and on electronbeam- pumped KrF laser which is only operated in single-shot mode.For the former,the TG-FROG can distinguish the changes of the pulse shape,spectrum and phase when the pulse chirp is changed.For the later,the TG-FROG finds that the pulse shape has multiple peaks whose pulse duration is about 2ps,and the spectrum is modulated whose bandwidth is about 1.3nm,and the corresponding phases present parabolic structure.
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