Research On Calibretion And Inversion Of Laser Induced Breakdown Spectroscopy For Detection Of Mars Substances

China's first Mars exploration mission has now started,which plans to launch in2020.One of the loads is Mars composition detector,which is expected to carry the LIBS instrument for detection of Mars Substance.In terms of the particularity of Mars surface detection Environment,LIBS has some unique advantages compared to other spectral techniques,for instance,enabling remote detection,analyzing fast and efficient,being able to peel off the dust on the surface of the rock.Those make LIBS an advanced technology with great potential in deep space exploration.This paper focuses on the key technologies of LIBS for the analysis of matter composition on the surface of Mars and provides a basis for our future Mars exploration in the future.Under laboratory conditions,this paper builds a LIBS analysis system for Mars LIBS technology research.The system has a 2-10m adjustable detection range.The time evolution process of LIBS signal is observed and analyzed.With high stability and high signal to noise ratio for the principle,the key parameters are optimized,such as pulsed laser energy of LIBS,integration time and delay time.In order to further enhance the LIBS signal,the research on collinear double pulses LIBS technology is carried out.The influence of the double pulse time interval and the pulse energy on the LIBS signal is analyzed.This paper uses the eight-channel spectral spectral module LIBS system.The spectral wavelength calibration of the LIBS system is carried out using standard light sources with different characteristic lines.Radiation calibration of the LIBS system is carried out using standard light sources with known spectral radiance energy.The wavelength response function and the radiation correction curve are established for each channel,and the model error is analyzed.Laboratory standard calibration uses standard samples.The plasma characteristic spectral line database was established for this LIBS system,and it matches the system and contains the main elements of the Martian material.The database is used for qualitative analysis by finding spectral peaks and recognition.This paper focuses on the data analysis and quantitative inversion method of LIBS.The LIBS signal preprocessing method is studied,which were used to reduce noise and optimize the signal.It contains baseline fitting algorithm,inter-channel overlapping spectral splicing algorithm,and db3 wavelet transform algorithm.For quantitative analysis,the calibration curve method,multiple linear regression method and partial least squares method are studied emphatically,which is used for calculate the silicon and aluminum content of rock.Then the model was evaluated.This paper designs the LIBS experiment in simulated Mars environment?300-900Pa,CO₂?.The changes of plasma signals were observed and analyzed.It was found that most of the plasma characteristic lines weakened,the background noise of LIBS signal is suppressed,the signal-to-noise ratio of characteristic spectrum is improved,and the plasma life is shortened.