Rapid Detection Of Trace Elements Of Co And Cs In Liquid By LIBS

As a kind of green power,nuclear power plays increasingly significant role in China power system.It is estimated that the installed capacity of nuclear power generation in China will reach more than 50% of the world by 2050.With the rapid development of nuclear power,nuclear safety issue has drawn more and more attention,and the fast detection of radioactive materials is an essential problem.The detection of nuclear power plants and nuclear waste produced mainly relies on gamma spectroscopy and neutron detection technology,which have limitations such as a long analysis time,inability to identify isotopes of α and β decay,failure of measuring non-radioactive impurities and so on.Laser induced breakdown spectroscopy（LIBS）has been widely used in various fields of basic research and industrial production as an element analysis technology due to the advantages of LIBS such as fast,convenient,real-time,and remote.In view of this,we introduced LIBS technology into radionuclide detection,and carried out research work on LIBS shortcomings such as high limit of detection and low stability.In this article,an experimental measurement platform for ns-LIBS and fs-LIBS was built.Carried out dielectric silica nanoparticles enhancement LIBS（NELIBS）research with nanosecond laser pulse and femtosecond laser pulse as excitation sources,and Co and Cs as target elements.Compared with the traditional LIBS technology,the signal enhancement of the target element is reached,and the detection sensitivity is effectively improved.The main work is divided two points.（1）The effect of silica NPs concentration and particle size on the enhancement of Co element ns-LIBS spectra was studied,and the spectral enhancement mechanism was explored.We used the finite time domain difference（FDTD）simulation to calculate enhancement to the electric field of the incident laser pulses over different particle sizes,a trend diagram consistent with the experiment was obtained.（2）Coaxial double-pulse LIBS and single-pulse LIBS were carried out based on the femtosecond laser.The variation trend of the double-pulse LIBS spectral intensity of Co,Cs,Al,Si and other elements with the laser pulse delay was obtained;meanwhile,the time evolution of the LIBS signal was measured using single-pules LIBS.Less spectral interference signals was obtained in fs-LIBS compared to ns-LIBS.By adding silica NPs to the target material the femtosecond LIBS was performed,compared to that the of single-pulse LIBS,the signal of Cs element was enhanced to a certain extent.Femtosecond laser LIBS are more sensitive than nanosecond LIBS techniques.In this study,the result of research is that ns-LIBS and fs-LIBS technology can be applied to the field of radioactive element analysis.Especially nanosecond laser NELIBS technology and femtosecond laser double-pulse LIBS technology can greatly improve the detection sensitivity of Co and Cs elements.It provides ideas for the practical application in the field of radioactive element analysis in the future.