Lifetime and Reliability of Rubidium Discharge Lamps for Use in Atomic Frequency Standards

The results of various studies concerning the lifetime and reliability of the rubidium discharge lamp used in the rubidium atomic frequency standards are reported. The primary life-limiting process in these lamps involves diffusion of the rubidium atoms into the glass envelope of the lamp, making them unavailable to the discharge. The rate at which rubidium atoms diffuse into the glass is dependent on lamp conditions, including lamp size, type of glass, lamp temperature, and rf drive power. The calorimetric technique to measure the elemental rubidium content in a lamp and its use for quality control in the lamp manufacturing process are discussed. Keywords include: Alkali discharge lamps, Atomic frequency standard, Rubidium atomic clocks, Rubidium lamps.