DTIC ADA219500: Atomic Velocity Distributions Out of pdf

DTIC ADA219500: Atomic Velocity Distributions Out of

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Velocity distributions are determined for atoms effusing out of radio frequency discharge hydrogen dissociators, of the type used in hydrogen masers. This work was motivated by long-term reliability issues related to the possible use of masers as frequency standards on satellites. A primary issue is the maser’s hydrogen budget, because many of the common failure modes of a maser involve either the hydrogen source or sink. Because the focusing properties of the state-selecting magnets are velocity dependent, the overall hydrogen budget will depend not only on the dissociation efficiency but also on the velocity distribution of the hydrogen atoms leaving the dissociation. Many times, that distribution has been tacitly assumed to be Maxwellian at wall temperature, but that assumption is not necessarily valid. Our measurements show the distributions to be much narrower than Maxwellian and to broaden as the hydrogen pressure in the dissociator increases. Operating the dissociator to yield a relatively narrow velocity distribution and using a state-selecting magnet well matched to that distribution may significantly improve the efficiency of hydrogen use by the maser.

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• Creator/s: Defense Technical Information Center
• Date: 2/15/1990
• Year: 1990
• Book Topics/Themes: DTIC Archive, Jaduszliwer, B, AEROSPACE CORP EL SEGUNDO CA CHEMISTRY AND PHYSICS LAB, *FREQUENCY STANDARDS, *MASERS, FAILURE, EFFICIENCY, ATOMS, HYDROGEN, ATOMIC CLOCKS, PRESSURE, BUDGETS, DISSOCIATION, RADIOFREQUENCY, DISTRIBUTION, VELOCITY, ARTIFICIAL SATELLITES

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