ultravacuum

English

Etymology

From ultra- +‎ vacuum.

Noun

ultravacuum (plural ultravacuums or ultravacua)

1. A nearly perfect vacuum; i.e. an almost or fully complete absence of matter, especially a gas at very low pressure.
   • 1946, The Paper Industry and Paper World, Volume 28, Issue 6‎^[1], Paper Industry Management Association, page 814:

     The operating principles employed in the thermal and ionization gauges are to be contrasted with the mercury manometer and Bourdon tube type vacuum gauges which have been used for years. The mechanics of these latter gauges seriously limit their use to the continuous measurement of high and ultravacuums.

   • 1951, Roy K. Marshall, The Nature of Things‎^[2], Henry Holt and Company, page 173:

     These lines are so-called “‘forbidden”’ lines which, in the crowded conditions even in a laboratory vacuum, would not appear; in the ultravacuum of a nebula, the atoms have no choice but to emit the forbidden energy.

   • 1959, Annual Review of Nuclear Science‎^[3], Palo Alto, Calif. Annual Reviews, pages 368-369:

     Some experiments which require the achievement of exceedingly antiseptic vacuum conditions have had to be preceded by intense research into the general problems of ultravacuums and surface physics. The problem of physical measurements on plasmas has required that many new instruments and techniques be developed.

   • 1964, American Chemical Society Division of Industrial and Engineering Chemistry, Industrial and Engineering Chemistry, Symposium on Interfaces, Sydney Ross, Chemistry and Physics of Interfaces‎^[4], American Chemical Society Publications, page 131:

     This behavior may be associated with chemical changes that are apparent in the composition of the gas phase as revealed by mass spectrometry techniques. Bursts of gas have been observed when a crystal is cleaved under ultravacuum conditions (117).

   • 1965, Analog - Science Fiction, Science Fact‎^[5], Trader Team, page 78:

     Then there are problems of measuring what goes on in an ultravacuum. This gadget is a tensile stress-testing machine—operating on samples in an ultravacuum chamber.

References

• “ultravacuum”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.
• “ultravacuum” in TheFreeDictionary.com, Huntingdon Valley, Pa.: Farlex, Inc., 2003–2024.