An Improved Rubidium Consumption Model for Discharge Lamps Used in Rubidium Frequency Standards,
Abstract
The rubidium (Rb) discharge lamp is a critical component of the Rb gas cell atomic frequency standard. This frequency standard is flying on NAVSTAR/global positioning system (GPS) satellites and will find applications on future satellites. The reliability of the lamp is an issue of concern, and aging of the lamp has been modeled in a satisfactory way for reliability determinations (Ref. 1). As the lamp ages, it slowly loses its Rb Charge by diffusion of Rb into the lamp's glass walls. The model equation for Rb consumption C is C = A + B square root, where T is lamp operating time and B is an experimentally determined diffusion-related coefficient. A has been assumed to be loss resulting from a virtually instantaneous reactive process. In some of our data sets, consumption measurements indicate that the reactive cleanup is time dependent. We find this dependence well described by a term with two constants, A' and D, resulting from first-order reaction kinetics: A' 1 - exp(-DT)). Including this term improves the ability to predict long-term Rb consumption on the basis of a limited amount of experimental data. Consumption model, Discharge lamp, Frequency standard, Lamp reliability, Rubidium. (mjm)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 15, 1989
- Accession Number
- ADA207562
Entities
People
- Robert A. Cook
- Robert P. Frueholz
Organizations
- The Aerospace Corporation