提出了一种积分球冷原子钟冷原子数稳定的新方法。该方法通过周期性地监测冷原子的吸收信号,利用反馈控制冷却激光内声光调制器的衍射效率并改变冷却光功率,实现冷原子数的稳定。推导了冷原子数稳定系统的环路方程,分析了稳定环路对冷原子数涨落的抑制作用。稳定后冷原子数的归一化涨落为1±0.001(3h),其功率谱密度在0.001~0.2Hz频率范围内的最大抑制量约为30dB。该涨落被抑制的原因主要是稳定环路除了直接补偿冷却光激光器输出的光功率变化外,还纠正了外界环境引起的冷原子数漂移。冷原子数稳定之后,由冷原子数涨落引起的原子钟频率稳定度可降低至7×10~(-14)τ~(-1/2)(τ为积分时间)。 A new method to stabilize the number of cold atoms in the cold sphere of integral sphere is proposed. The method realizes the stabilization of the number of cold atoms by periodically monitoring the absorption signals of the cold atoms, controlling the diffraction efficiency of the laser acousto-optic modulator by feedback control and changing the cooling light power. The loop equations of the cold atomic number stability system are deduced. The inhibition of the steady-state loop on the number fluctuations of cold atoms is analyzed. The normalized fluctuation of the number of stable postcooling atoms is 1 ± 0.001 (3h), and the maximum suppression of the power spectral density in the frequency range of 0.001-0.2Hz is about 30dB. The reason for the fluctuation is suppressed is that the stability loop not only directly compensates the optical power output from the cooling optical laser, but also corrects the drift of cold atoms caused by the external environment. After the number of cold atoms is stabilized, the atomic clock frequency stability caused by the fluctuations of the number of cold atoms can be reduced to 7 × 10 ~ (-14) τ ~ (-1/2) (τ is the integration time).