摘要
利用快速存贮示波器 ( 10 0MHz)对脉冲激光烧蚀固体Al靶产生的等离子体信号的飞行时间特征进行了测量 .在YAG脉冲激光基频输出 (脉宽 10ns ,波长 1 0 6μm ,能量 10 8mJ/pulse)、烧蚀斑的直径为 2 0 0 μm、靶面上激光功率密度约为 1× 10 11W/cm2 的条件下 ,分别在靶和靶前方的探极测到带电粒子信号 .通过这些信号的飞行时间轮廓 ,观测到持续时间与激光脉宽相当的峰值极大的快速光电子和持续时间达 μs的等离子体中的热电子 ,并估算出快速光电子的平均速度在 10 7cm/s以上 .同时测得离子动能达几百eV .实验还表明 ,真空度对信号轮廓有很大影响 ,结合光谱实验的结果 ,给予了适当的解释 .
Using fast store oscilloscope(100?MHz, fast writing speed 1?000?DIV/μs),the time of flight profiles of electrical signals induced by laser ablated Al target has been measured.The Q switch YAG laser runs at its foundational frequency 1 06?μm with 10?ns pulse width and 108?mJ/pulse, the ablation point diameter is 200?μm, so the laser irradiation flux is about 10×10 11 ?W/cm 2. Abundant electrical signals are observed on target and probe simultaneously.A fast rising transient electron peak that has almost the same duration of the laser is observed,its average speed is more than 10 7?cm/s.Meanwhile,the ion kinetic energy is about several hundred electron volts.Besides this, the experiments have shown that vacuity has strong influence to the time of flight profile.Considering the results obtained from spectra experiments,an appropriate explanation is given.
出处
《西北师范大学学报（自然科学版）》
CAS
2001年第1期50-55,共6页
Journal of Northwest Normal University(Natural Science)
基金
国家自然科学基金资助项目!( 19874 0 51)
