激光诱导Al等离子体连续辐射的时间分布

用Ar作环境气体，压强固定在10kPa，每个激光脉冲能量为115mJ，利用时空分辨技术，采集激光烧蚀Al靶产生的等离子体辐射的时间分辨谱。分析了Al等离子体连续辐射特征。简要讨论了激光诱导等离子体连续辐射的产生机理。提出了原子对激光诱导等离子体连续辐射共振吸收理论。激光诱导等离子体的连续辐射的主要机制是轫致辐射和复合辐射，在激光脉冲作用到靶面瞬间，轫致辐射占主导地位；等离子体演化初期，复合辐射和轫致辐射共同产生等离子体连续辐射；等离子体演化后期，连续辐射主要复合辐射产生的。Al原子对连续辐射的共振吸收是选择性的，这是改变连续辐射按波长“平滑”分布的主要机制。

Time Distribution of the Continuum Radiation in the Plasma Induced by Laser Ablating Al

With time- and space- resolved technique, the time-resolved spectra of the plasma induced by Nd∶YAG laser ablating metal aluminum in Ar were recorded, in which, laser pulse energy was set up to 115 mJ and the buffer pressure 10 kPa. The continuum radiation of aluminum plasma was studied. The mechanism of the continuum radiation of the plasma induced by laser ablating aluminum is discussed. Resonantly absorbing continuum radiation was suggested. Bremsstrahlung and compound radiation of electron were considered as main mechanism of continuum radiation. Short after the laser beam getting to the surface of the target, Bremsstrahlung is the primary mechanism of the continuum, during early stage of the plasma involution the continuum radiation derives from Bremsstrahlung and compound radiation of electron; but during late stage the continuum emission only comes from compound radiation of electron. Atom Al selectively absorbs continuum radiation, it leads to the change of the smooth distribution of continuum emission with wavelength under normal condition.