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Modifying Operating Cycles to Increase Stability in a LITSThe short-term instability in the frequency of a linear-ion-trap frequency standard (LITS) can be reduced by modifying two cycles involved in its operation: (1) the bimodal (bright/dim) cycle of a plasma discharge lamp used for state preparation and detection and (2) a microwave-interrogation cycle. The purpose and effect of the modifications is to enable an increase in the microwave- interrogation cycle time, motivated by the general principle that the short-term uncertainty or instability decreases with increasing microwave-interrogation time. Stated from a slightly different perspective, the effect of modifications is to enable the averaged LITS readings to settle to their longterm stability over a shorter total observation time. The basic principles of a LITS were discussed in several NASA Tech Briefs articles. Here are recapitulated only those items of background information necessary to place the present modifications in context. A LITS includes a microwave local oscillator, the frequency of which is stabilized by comparison with the frequency of a ground-state hyperfine transition of Hg-199(+) ions. In a LITS of the type to which the modifications apply, the comparison involves a combination of optical and micro wave excitation and interrogation of the ions in two collinear ion traps: a quadrupole trap wherein the optical excitation used for state preparation and detection takes place, and a multipole (e.g., 12-pole) trap wherein the microwave interrogation of the clock transition takes place. The ions are initially loaded into the quadrupole trap and are thereafter shuttled between the two traps. This concludes the background information.
Document ID
Acquisition Source
Jet Propulsion Laboratory
Document Type
Other - NASA Tech Brief
Burt, Eric
(California Inst. of Tech. Pasadena, CA, United States)
Tjoelker, Robert
(California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 24, 2013
Publication Date
August 1, 2009
Publication Information
Publication: NASA Tech Briefs, August 2009
Subject Category
Technology Utilization And Surface Transportation
Report/Patent Number
Distribution Limits
Public Use Permitted.
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