Spectra correction is essential for the quantification of laser-induced breakdown spectroscopy(LIBS) due to the uncertainties in plasma morphology.In this work,we determined the plasma morphology using a charge-couple...Spectra correction is essential for the quantification of laser-induced breakdown spectroscopy(LIBS) due to the uncertainties in plasma morphology.In this work,we determined the plasma morphology using a charge-coupled device camera and introduced the spectral correction method based on plasma images to a combustion environment.The plasma length,width,volume,and location were extracted from the plasma images.Using a back-scattering setup,the contribution of plasma location fluctuation to the total spectral fluctuation was mitigated.The integral intensity of the plasma image was used as a proxy of the total number density to correct the spectra.Linear relationships were established between the integral intensities of the plasma images and the spectral intensities,under different laser energy levels and gas temperatures.The image-based correction method could significantly reduce the fluctuation of raw spectral intensities when the laser energy was below 240 mJ.Compared with the correction method based on total spectral areas,the proposed method offered significant improvements in the low energy region,which promises to reduce the signal fluctuations in combustion environments while preserving the spatial resolution and mitigating the flow disturbance.展开更多
In this paper,the transfer functions of ultrasonic transducers under different temperatures are imitated according to Mason equivalent circuit. The relevant experiments are carried out. The results show that the trans...In this paper,the transfer functions of ultrasonic transducers under different temperatures are imitated according to Mason equivalent circuit. The relevant experiments are carried out. The results show that the transfer characteristic of ultrasonic transducer varies with temperature and pressure. Therefore, we present an approach to correct the amplitude spectra of ultrasonic echoes got in different temperature and pressure environmeots. The theoretical simulation and experimental results prove that the approach is simple, effective and practical.展开更多
基金supported by National Natural Science Foundation of China(No.51906149)the Natural Science Foundation of Shanghai(Nos.20ZR1428500,21DZ1205300)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(No.SL2020ZD202)。
文摘Spectra correction is essential for the quantification of laser-induced breakdown spectroscopy(LIBS) due to the uncertainties in plasma morphology.In this work,we determined the plasma morphology using a charge-coupled device camera and introduced the spectral correction method based on plasma images to a combustion environment.The plasma length,width,volume,and location were extracted from the plasma images.Using a back-scattering setup,the contribution of plasma location fluctuation to the total spectral fluctuation was mitigated.The integral intensity of the plasma image was used as a proxy of the total number density to correct the spectra.Linear relationships were established between the integral intensities of the plasma images and the spectral intensities,under different laser energy levels and gas temperatures.The image-based correction method could significantly reduce the fluctuation of raw spectral intensities when the laser energy was below 240 mJ.Compared with the correction method based on total spectral areas,the proposed method offered significant improvements in the low energy region,which promises to reduce the signal fluctuations in combustion environments while preserving the spatial resolution and mitigating the flow disturbance.
文摘In this paper,the transfer functions of ultrasonic transducers under different temperatures are imitated according to Mason equivalent circuit. The relevant experiments are carried out. The results show that the transfer characteristic of ultrasonic transducer varies with temperature and pressure. Therefore, we present an approach to correct the amplitude spectra of ultrasonic echoes got in different temperature and pressure environmeots. The theoretical simulation and experimental results prove that the approach is simple, effective and practical.
