通过建立涉及克尔效应和多光子电离效应的非线性数学模型，利用数值方法研究了超短激光脉冲在大气传播中的自聚焦行为。结果表明由自聚焦导致的成丝现象具有间断性，而不是一种稳态的模式。每次轴上的成丝都会由于光场损耗而减弱，但同时由于克尔效应会使离轴区域的能量间断地补充到光轴上。

The behavior of self focusing of the ultra short intense laser pulse during propagating in atmosphere was studied, particularly, using the numeric solution of a time dependent Schdinger equation on account of Kerr effect and multi photon ionization (MPI) effect. The result implies the intermittence, rather than the stable structure, of the filamentation caused by self focusing. Each on axis filamentation will decay due to the ionization while the off axis energy will replenish to the on axis region intermittently due to Kerr effect.