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Title: Generation of ion-acoustic waves in an inductively coupled, low-pressure discharge lamp

For a number of years it has been known that the alkali rf-discharge lamps used in atomic clocks can exhibit large amplitude intensity oscillations. These oscillations arise from ion-acoustic plasma waves and have typically been associated with erratic clock behavior. Though large amplitude ion-acoustic plasma waves are clearly deleterious for atomic clock operation, it does not follow that small amplitude oscillations have no utility. Here, we demonstrate two easily implemented methods for generating small amplitude ion-acoustic plasma waves in alkali rf-discharge lamps. Furthermore, we demonstrate that the frequency of these waves is proportional to the square root of the rf power driving the lamp and therefore that their examination can provide an easily accessible parameter for monitoring and controlling the lamp's plasma conditions. This has important consequences for precise timekeeping, since the atomic ground-state hyperfine transition, which is the heart of the atomic clock signal, can be significantly perturbed by changes in the lamp's output via the ac-Stark shift.
Authors:
;  [1]
  1. Electronics and Photonics Laboratory, The Aerospace Corporation, P.O. Box 92957, Los Angeles, California 90009 (United States)
Publication Date:
OSTI Identifier:
20788089
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 99; Journal Issue: 8; Other Information: DOI: 10.1063/1.2191568; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ATOMIC CLOCKS; GROUND STATES; HIGH-FREQUENCY DISCHARGES; ION ACOUSTIC WAVES; LIGHT BULBS; OSCILLATIONS; PLASMA; SIGNALS