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利用CO2激光烧蚀锡靶产生等离子体,当入射到靶面的单个脉冲能量为400mJ,半峰全宽(FWHM)为75ns时,使用光谱仪和增强型电荷耦合器件(ICCD)采集了等离子体的时间分辨光谱。在局域热平衡假设下,利用谱线的斯塔克展宽和五条Sn II谱线的相对强度计算并得到了等离子体电子密度、电子温度和辐射谱线强度随时间的变化规律;利用掠入射极端紫外平场光栅光谱仪,结合X射线CCD同时探测了光源在6.5～16.8nm波段的时间积分极端紫外辐射光谱。实验结果表明:激光点燃等离子体早期的100ns内有很强的连续谱,此后才能分辨出明显的原子和离子线状谱。在延时0.1～2.0μs的时间区间内,等离子体中的电子温度和密度分别在2.3～0.5eV和7.6×1017～1.2×1016 cm-3范围内,均随时间经历了快速下降,然后再较缓慢下降的过程。激光锡等离子体极端紫外不可分辨辐射跃迁光谱峰值中心位于13.5nm,FWHM为1.1nm。
Plasma was generated using a CO2 laser ablating a tin target and the plasma was collected using a spectrometer and an enhanced charge coupled device (ICCD) when the single pulse energy incident on the target surface was 400 mJ and the full width at half maximum (FWHM) was 75 ns Time-resolved spectroscopy. Under the assumption of local thermal equilibrium, the variation of electron density, electron temperature and radiation line intensity over time of the plasma were calculated by using the Stark broadening of the spectrum and the relative intensities of the five Sn II lines. UV flat-field grating spectrometer, combined with X-ray CCD at the same time detected the light source in the 6.5 ~ 16.8nm time-band extreme ultraviolet radiation spectrum. The experimental results show that there is a strong continuous spectrum in the early 100 ns of the laser-ignited plasma, and obvious linear spectra of atoms and ions can be distinguished thereafter. The electron temperature and density in the plasma ranged from 2.3 to 0.5eV and from 7.6 × 1017 to 1.2 × 1016 cm-3 in the time interval of 0.1 ~ 2.0μs, respectively. Both of them experienced rapid decline with time, and then Slower decline process. The peak of the ultraviolet spectrum of the laser tin plasma at the extreme ultraviolet unresolved radiation transition is located at 13.5nm and the FWHM is 1.1nm.