Structure of deep-sea laser-induced breakdown spectroscopy experimental equipment

The exploration and development of marine resources has become a hot spot in the exploration and development of mineral resources in the world. As a deep-sea detection technique, Laser-induced breakdown spectroscopy (LIBS) has advantages of fast detection speed, no need to pretreat the sample, real-time in situ, and can be applied to liquid medium. However, due to the almost incompressible nature of water and its cooling effect on high-temperature plasma, the sensitivity of deep-sea LIBS detection is low and the influence of pressure is obvious.

To solve this problem, the LIBS team from the Shenyang Institute of Automation, Chinese Academy of Sciences (SIACAS) proposed a method of injecting helium into the measuring probe, to create a gas environment in the deep-sea high-pressure water environment, which broke the bottleneck of difficult excitation of plasma signals in deep-sea high-pressure water.

This method uses a probe to transfer high-pressure gas to the surface of a solid sample, and the gas will discharge the water on the surface of the sample, thus forming a high-pressure gas environment.

The research team carried out LIBS characteristics studies under different pressures, proving that the method of creating the helium environment can effectively enhance the LIBS signal, and obtained effective spectral data at 60MPa (corresponding to the water pressure of 6000m in the deep sea).

The results show that increasing the laser energy and shortening the laser transmission distance in high-pressure gas can effectively improve the spectral signal intensity, which is different from the conclusion in the high-pressure water environment.

The above research results show that the method of transforming water environment into gas environment can effectively avoid the influence of high-pressure water on LIBS detection, and provide a new solution for deep-sea mineral in-situ detection.

Subsequently, the team will develop a sensor prototype system for deep-sea in-situ detection on the basis of the research results, and further carry out the application and verification work of sea trials.

The result has been published in the journal, Talanta titled Study on laser-induced breakdown spectroscopy in high-pressure helium gas environment for deep ocean applications. This work was supported by the National Key Research and Development Program of China.