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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 excitation of the photon of the fluorescence echo of the laser sodium beacon in the middle layer of the atmosphere is affected by the geomagnetic field, sodium atom collisions and recoil. The geomagnetic field caused the precession of the sodium atom by Larmor, which seriously weakened the optical pumping by long-pulse and continuous-wave laser interaction with sodium atom. Atomic collision increased the mean fluorescence photon flux of sodium fluorescence to a certain extent, while the recoil decreased Sodium fluorescence average echo photon flux. In addition, the lower pumping phenomenon easily lead to sodium atomic optical pumping into the saturation transition at lower light intensity. Therefore, in order to increase the number of sodium fluorescence echo photons, you can use the method of resuming the pumping to obtain a higher sodium fluorescence average echo photon flux. The results of numerical simulation show that the sodium fluorescence echo photon number obtained by adding 16% of the re-pumping energy to the laser beam is approximately 2.33 times that of the sodium fluorescence echo excited by the single frequency (D2a) under the Greenwood atmospheric turbulence model .