Fig. 1. Schematic diagram of LIBS experiment apparatus

Fig. 2. Diagram of experimental scene

Fig. 3. Characteristic spectrum of Si and Al in LIBS with and without cavity restriction

Fig. 4. Spectral line intensity of Al and Si elements under different pressures. (a) Si Ⅰ 288.15 nm; (b) Al Ⅰ 308.21 nm

Fig. 5. Spectral intensities of Al and Si elements change with laser energy under two LIBS conditions. (a) LIBS; (b) CC-LIBS

Fig. 6. SNR of Al and Si elements vary with laser energy. (a) Si Ⅰ 288.15 nm; (b) Al Ⅰ 308.21 nm

Fig. 7. Spectral intensities of Al and Si elements change with the acquisition delay time under two LIBS conditions. (a) LIBS; (b) CC-LIBS

Fig. 8. SNR of Al and Si elements vary with the acquisition delay time. (a) Si Ⅰ 288.15 nm; (b) Al Ⅰ 308.21 nm