大气中间层激光钠信标荧光回波光子的激发受到地磁场、钠原子碰撞以及反冲的影响。地磁场引起钠原子的拉莫尔进动，严重地削弱长脉冲和连续波激光与钠原子作用的光抽运；原子碰撞一定程度上增加了钠荧光平均回波光子通量；反冲却降低了钠荧光平均回波光子通量。此外，下抽运现象容易导致钠原子光抽运在较低的光强下进入跃迁饱和。因此，为了增加钠荧光回波光子数，可以采用再抽运的方法获得较高的钠荧光平均回波光子通量。数值模拟的结果表明，在Greenwood大气湍流模式下，在激光束中加入16%的再抽运能量获得的钠荧光回波光子数大约是单一频率（D2a）激发钠荧光回波光子数的2.33倍。

The geomagnetic field, sodium atomic collision and recoil can affect the number of return photons from sodium laser beacon at the sodium layer in mesosphere. The geomagnetic field can cause Larmor precession of sodium atoms and severely reduce the optical pumping when the long pulse and the continuous wave laser act on sodium atoms. Furthermore, the atomic collision can increase the average return photon flux on a certain extent, while recoil decreases it. In addition, downpumping easily causes optical pumping into transition saturation under lower light intensity. In order to get more return photons, repumping may be used to enhance the average return photon flux. The numerical simulation indicates that the laser with 16% repumping power can excite the number of return photons as 2.33 times of the signal\|frequency (D2a) laser.