椭圆偏振场中原子隧穿电离的残存问题研究

The study of survival for tunneling ionized atom in an elliptically polarized laser field

利用三维半经典系综模拟方法,研究了原子在椭圆偏振场中的残存问题.结果发现,对于电离能比较大的原子(如氦原子),残存原子是由于电子的初始横向速度与漂移速度相互抵消造成的,对于电离能比较小的原子(如镁原子),核的库仑吸引对原子的残存起主要作用.我们提出残存窗口理论来反映库仑作用,从该理论所得中性原子产率分布比强场近似模型更接近三维半经典数值模拟结果.另外,电离能小的原子残存率随椭偏率分布对激光强度大小比较敏感,可以利用这一特性来标定超强场激光的强度.

By using the method of three-dimensional semiclassical electron ensemble simulation, we study the survival mechanism of tunneling ionized atom in an elliptically polarized field. It is found that for atoms with bigger ionization potential such as helium, the unionized atoms are mainly caused by the balancing of electron initial transverse velocity with the drifting velocity. For atoms with smaller ionization potential such as magnesium, Coulomb attraction plays the major role in the survival of atoms. We find a survival window to reflect the effect of Coulomb force. Result from this theory is closer to the three-dimensional semiclassical simulation than the strong-field approximation model. In addition, the distribution of survival yield on ellipticity for atoms with smaller atoms is sensitive to laser intensity which can be used to measure the intensity of super-strong laser pulses.