For nuclear security and safeguard, it is necessary to detect and identify nuclear materials. Laser-induced Plasma Spectroscopy (LIPS,also LIPS) has great potential to rapid identify the elemental composition for on-site nuclear inspection and forensic. To demonstrate the application of on-site identification of suspicious materials, a portable LIPS device was set up. The detection sensitivity of the device for uranium is about tens of ppm. Tests were carried out to identify suspicious materials, each sample was identified within seconds. The results show that the device has successfully identified nuclear materials from the samples with disturbances. It is demonstrated that the portable LIPS can identify target elements in nuclear material on site, providing a novel technology for nuclear security.
Laser induced plasma spectroscopy (LIPS, also LIBS) is a promising technique for the challenging issues associated with the real-time and in-situ monitoring the major elements of aerosol particulate matters. A prototype of Aero-LIPS had been set up with the techniques of aerosol beam focusing, enhanced plasma emission collector and conditional data filter to demonstrate the potential application of air pollution composition monitoring. The prototype can identify more than 40 elements from aerosols and continuously monitor 20 elements with the time resolution of 10 minutes. In the field test of an Asian dust event, the major elements, such as Ca, Mg, Al, Si, Cl, P, S, etc. have been real-time monitored, which took 77.9% part of the total particulate matter mass. The evolutions of temporal elemental concentrations went well along with the particle matter concentration. It is interesting that several persist lines of U and Th have been detected from Asian dust aerosol while their concentration in local air should range in the level of nano-grams per cubic-meter. It might indicate that the enhanced-LIPS has a potential to monitor the nuclear facility emission for Nuclear Security and Safeguards.
The fused silica is an important optical material in the large laser devices, which are often subject to laser induced damage in the laser systems. In this work we studied nanosecond laser induced damage in JGS1 fused silica at the three harmonic wavelengths of the 1064 nm, 355 nm and 248 nm. Under 1064nm/10ns, 355nm/10ns and 248nm/22.8ns laser irradiation, the bulk damage threshold is 150 J/cm2, 15 J/cm2 and 7 J/cm2, respectively. The results showed that the weakest point of bulk damage threshold among the three tested wavelengths is 248 nm. And the damage threshold decreases sharply with the decrease of wavelength.
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.
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.
Laboratory air is one most popular transparent medium for high power laser beam propagation. Its threshold of laser induced breakdown is one of the key characters for the high power laser system. The thresholds of laser induced air breakdown under laboratory condition were measured using 1064, 532, 355, 266 and 248nm short pulse laser. The focal spot varies from 50μ m to 150μ m which achieved using a lens with 117mm focal length. The measured breakdown thresholds range from 3.2×1010W/cm2 to 5.1×1011W/cm2, depending on the wavelength. It is confirmed that the KrF laser induced air breakdown threshold should be 3.2×1010W/cm2, which is almost 1 order of magnitude higher than the reported value of 2.7 ×109W/cm2 .The measurements indicate multi-photon ionization is the dominant mechanism since the air breakdown thresholds at 1064, 532, 355, 266 and 248nm seemed well-agreed with the scale law of λ2.
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