铬原子束横向一维激光冷却的蒙特卡罗方法仿真

Simulations of one-dimensional transverse laser cooling of Cr atomic beam with Monte Carlo method

激光汇聚铬原子沉积实验中,铬原子束准直度的好坏非常重要.利用蒙特卡罗随机思想选取原子轨迹初始条件,将52Cr原子以外的其他同位素、纵向速度分布和横向发散角等因素综合考虑,对铬原子束横向一维激光冷却进行了优化分析.经过与均匀取值法比较,这种方法能够更好地体现原子运动的不确定性,挑选出不参与冷却过程的同位素,使考察界面内原子束的横向位置分布更好的符合实验结果.结果显示,冷却过程中其他同位素的存在使原子束横向位置分布的中心最大值减小9.3%,半高宽增加11%,并且增加轮廓曲线的基底.

A well collimated atomic beam plays an important role in laser focused Cr atom deposition.The simulations of one-dimensional （1D） transverse laser cooling of Cr atomic beam is performed with the Monte Carlo method.Taking into account the stochastic initial conditions of each atom,isotopes other than 52Cr,longitudinal velocity distribution and transverse divergence,the atomic beam cooled by laser is optimized and evaluated.The obtained results are consistent with experimental.In addition,with picking out the trajectories of isotopes other than 52Cr that are not cooled by the laser the center maximum value can be reduced by 9.3%,and the FWHM is increased by 11% of the transverse distribution.