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Buffer Gas Experiments in Mercury (Hg+) Ion ClockWe describe the results of the frequency shifts measured from various buffer gases that might be used as a buffer gas to increase the loading efficiency and cooling of ions trapped in a small mercury ion clock. The small mass, volume and power requirement of space clock precludes the use of turbo pumps. Hence, a hermetically sealed vacuum system, incorporating a suitable getter material with a fixed amount of inert buffer gas may be a practical alternative to the groundbased system. The collision shifts of 40,507,347.996xx Hz clock transition for helium, neon and argon buffer gases were measured in the ambient earth magnetic field. In addition to the above non-getterable inert gases we also measured the frequency shifts due to getterable, molecular hydrogen and nitrogen gases which may be used as buffer gases when incorporated with a miniature ion pump. We also examined the frequency shift due to the low methane gas partial pressure in a fixed higher pressure neon buffer gas environment. Methane gas interacted with mercury ions in a peculiar way as to preserve the ion number but to relax the population difference in the two hyperfine clock states and thereby reducing the clock resonance signal. The same population relaxation was also observed for other molecular buffer gases (N H,) but at much reduced rate.
Document ID
20070031783
Acquisition Source
Jet Propulsion Laboratory
Document Type
Preprint (Draft being sent to journal)
External Source(s)
Authors
Chung, Sang K.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Prestage, John D.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Tjoelker, Robert L.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Maleki, Lute
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 23, 2013
Publication Date
August 23, 2004
Subject Category
Space Sciences (General)
Meeting Information
Meeting: IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society
Location: Montreal
Country: Canada
Start Date: August 24, 2004
Sponsors: Institute of Electrical and Electronics Engineers
Distribution Limits
Public
Copyright
Other
Keywords
mercury ion clock
buffer gas

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