Corona homogeneity and spectra of scattered light and hot electrons produced by laser-plasma instabilities inside laser-produced plastic, aluminum, and gold plasmas were investigated with and without the use of continuous phase plate (CPP) to the laser beam. Improvement of the corona homogeneity was observed for all three materials after applying CPP, while the inhibition of the intensity of backward-scattered light and the amount of emitted hot electrons was not always synchronous for different materials, which is interpreted as a result of the changes in thresholds of the stimulated Raman scattering (SRS) and the two-plasmon decay (TPD) instability before and after the application of CPP. By comparing the changes of SRS scattered light intensity with the amount of hot electrons in different kinetic energy ranges for all three target materials in our experiments, we conclude that SRS is more responsible for the diagnosed hot electrons between 50–150 keV, and those above 150 keV should be generated by TPD, which could be explained by the difference in phase velocity of electron plasma waves between SRS and TPD calculated from measured and simulated parameters of corona and laser-plasma instabilities.
摘要： 在有无连续相位板（CPP）作用于激光束的条件下，研究了激光产生等离子体中的塑料、铝和金靶材的日冕均匀性以及散射光与热电子光谱。对三种靶材施加CPP后，均观察到日冕均匀性改善，同时散射光量和热电子温度降低。此外，在有无CPP的情况下，均观察到受激拉曼散射（SRS）和双等离子体衰变（TPD）信号，且CPP抑制了这些不稳定性。通过对比不同靶材，发现金靶材的SRS和TPD信号最强，热电子温度最高，而塑料靶材的信号最弱。实验结果表明，CPP有效抑制了激光等离子体不稳定性，且靶材原子序数越高，不稳定性越强。