强激光场下原子超快动力学过程中的能量交换

利用三维经典系综模型,研究了整个系综两电子(Ar原子为例)从激光场吸收的能量对激光参数(波长、激光强度和椭偏率)的依赖关系.结果显示,当激光强度固定,波长增加时,整个系综两电子从激光场吸收的能量整体呈上升趋势,但不同强度下趋势略有差异.在较低强度时整个系综两电子从激光场吸收的能量对波长的依赖关系呈现持续平稳增加的趋势,在较高强度时呈现先缓慢减小再快速增大的趋势.对强度的依赖关系在不同波长时呈现两个有趣的交叉点.对椭偏率的依赖关系在较低强度时呈现先逐渐减小再缓慢增大的趋势;在中等强度时呈现一个“阶梯型”即先缓慢增大再逐渐减小最后缓慢增大;在更高强度时呈现先逐渐增大再逐渐减小的趋势.为了解释整个系综两电子从激光场吸收的能量对激光参数的依赖关系,把整个系综的动力学过程分为双电离、单电离、受挫单电离和受挫双电离4种通道.然后分析各个通道的特征及其如何主导整个系综两电子从激光场吸收的能量的变化趋势.分析结果表明,整个系综两电子从激光场吸收的能量对波长、激光强度和椭偏率的依赖均是由于某种通道主导整个系综两电子从激光场吸收的能量的结果.

Energy exchange in ultrafast dynamics of atom with strong laser fields

Using the three-dimensional classical ensemble model,we investigate the dependence of the energy absorbed by two electrons(Ar atom as an example)from the laser field on the laser parameters(wavelength,laser intensity and ellipticity).The results show that when the laser intensity is fixed and the wavelength increases,the energy absorbed by the two electrons from the laser field increases as a whole,but the trend is slightly different under different intensities.At lower intensity the dependence of the energy absorbed by the two electrons from the laser field on wavelength increases steadily and at higher intensity it decreases slowly and then increases rapidly.The intensity dependence of the energy absorbed by two electrons from the laser field in the whole ensemble presents two interesting intersections at different wavelengths.The dependence of the energy absorbed by the two electrons from the laser field on the ellipticity first decreases and then increases slowly at lower intensity;it has a“Ladder shape”that slowly increases and then decreases and finally slowly increases at moderate intensity;it shows a trend of increasing first and then decreasing at higher intensities.In order to explain the dependence of the energy absorbed by two electrons from the laser field on the laser parameters(wavelength,laser intensity and ellipticity),the kinetic process of the whole ensemble is divided into four channels:double ionization,single ionization,frustrated single ionization and frustrated double ionization.The characteristics of each channel and how it dominates the overall trend of energy absorption from the laser field by the two electrons are then analyzed.The analysis results show that the dependence of the energy absorbed by the two electrons from the laser field on wavelength、laser intensity and ellipticity is due to the fact that some channels dominate the energy absorbed by the two electrons from the laser field.