Study on Long Term Stability of Rubidium Atom Frequency Standard

The present status of rubidium atom frequency standard is introduced. The factors influencing long-term stability were discussed such as the light frequency shift, collision frequency shift and microwave power frequency shift. When pumping light spectral function has small change, it will cause light shift. The method of reducing light shift was to control the slope between the light shift curve and collision shift curve until they were equal in value but opposite in direction. For reducing collision frequency shift, the rubidium absorbs cell with special glass was adopted to weaken the chemical reaction in the experiment. We believed that the new reason based on AC Zeeman effect was the main one to influence microwave power frequency shift, so the traditional explanation was not the main factor. In the experiment, microwave power frequency shift is eliminated through the circuit improvement. Therefore, better long-term stability can be obtained. The performance of rubidium atom frequency standard is greatly improved