The characteristics of the multiple filamentation domain of femtosecond laser pulses in air have been estimated based on the single filamentation model. The diffraction-ray model is considered as the single filamentation model. It is based on representation of a laser beam by a set of diffraction-ray tubes nested into each other that do not intersected in space and do not exchange by their energies. In this situation, changes in the tube shapes and cross sections during beam propagation demonstrate the effect of physical processes that occur with radiation in the medium. It is shown that this model is efficient for interpreting experimental results. In particular, it has been demonstrated that the radius of small-scale intensity inhomogeneities in the profile of a centimeter laser beam forming the multiple filamentation domain of subterawatt femtosecond laser pulses is several millimeters. The power in these inhomogeneities varies from several units to several tens of gigawatts. Telescoping the initial laser beam that caused an increase in its radius also increased sizes of the initial smallscale intensity inhomogeneities and decreased the power contained in them. As a result, the coordinate of the filamentation onset is shifted along the propagation path from the laser pulse source. The lengths of the filaments and their number increase with the peak beam power.

基于单丝模型，估算了空气中飞秒激光脉冲的多丝区域的特性。衍射射线模型被认为是单丝化模型。它是基于一组互相嵌套的衍射射线表示的，这些衍射射线在空间上不相交并且不通过其能量进行交换。在这种情况下，光束传播过程中管形和横截面的变化证明了介质中辐射发生的物理过程的影响。结果表明，该模型对于解释实验结果是有效的。特别是，业已证明，形成小于兆瓦的飞秒激光脉冲的多丝状区域的厘米激光束轮廓中的小尺度强度不均匀半径为几毫米。这些不均匀性中的功率从数个单位到几十吉瓦不等。伸缩导致其半径增加的初始激光束也会增加初始小规模强度不均匀性的大小，并降低其中包含的功率。结果，丝状开始的坐标从激光脉冲源沿着传播路径移动。细丝的长度及其数量随峰值光束功率而增加。伸缩导致其半径增加的初始激光束还会增加初始小规模强度不均匀性的大小，并降低其中包含的功率。结果，丝状开始的坐标从激光脉冲源沿着传播路径移动。细丝的长度及其数量随峰值光束功率而增加。伸缩导致其半径增加的初始激光束也会增加初始小规模强度不均匀性的大小，并降低其中包含的功率。结果，丝状开始的坐标从激光脉冲源沿着传播路径移动。细丝的长度及其数量随着峰值光束功率的增加而增加。