Investigation of gas species in a stainless steel ultrahigh vacuum chamber with hot cathode ionization gauges

Hong, S. S.; Shin, Young-Han; Arakawa, Ichiro

doi:10.1088/0957-0233/15/2/007

Cited by 8 publications

(7 citation statements)

References 16 publications

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“…Initially, the loss rate versus trap depth at the apparatus base pressure is recorded. These losses are due to common vacuum system species such as H 2 and CO [32,33]. In addition to external gas collisions, the baseline loss rate includes Majorana losses and/or 2-and 3-body intratrap losses, Γ 0 .…”

Section: Discussionmentioning

confidence: 99%

Universality of quantum diffractive collisions and the quantum pressure standard

et al. 2019

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This work demonstrates that quantum diffractive collisions are governed by a universal law characterized by a single parameter that can be determined experimentally. Specifically, we report a quantitative form of the universal, cumulative energy distribution transferred to initially stationary sensor particles by quantum diffractive collisions. The characteristic energy scale corresponds to the localization length associated with the collision-induced quantum measurement, and the shape of the universal function is determined only by the analytic form of the interaction potential at long range. Using cold 87 Rb sensor atoms confined in a magnetic trap, we observe experimentally p QDU6 , the universal function specific to van der Waals collisions, and use it to realize a self-defining particle pressure sensor that can be used for any ambient gas. This provides the first primary and quantum definition of the Pascal, applicable to any species and therefore represents a fundamental advance for vacuum and pressure metrology. The quantum pressure standard realized here is compared with a state-of-the-art orifice flow standard transferred by an ionization gauge calibrated for N 2 . The pressure measurements agree at the 0.5% level. m d 4 2 t  º p s ̶ [4]. Here m t is the mass of the sensor particle and s ̶ is the thermally-averaged total collision cross section, including contributions from both elastic and inelastic scattering. We further demonstrate that s ̶ is independent of the short-range interaction between the colliding particles with van der Waals long-range interactions.It is well known that collisions resulting in small momentum transfer are dominated by quantum diffractive scattering [4,5]. Such collisions occur with small scattering angles 0 q  and are predominantly determined by OPEN ACCESS RECEIVED

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Section: Discussionmentioning

confidence: 99%

Universality of quantum diffractive collisions and the quantum pressure standard

et al. 2019

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“…The same calibration procedure was applied to three molecular species, Hydrogen (H 2 ), Nitrogen (N 2 ), and Carbon Dioxide (CO 2 ). They were selected because of their importance in many vacuum systems [38,39]. Unlike atoms, these species have a rich internal structure and can undergo both elastic and inelastic collisions.…”

Section: Methodsmentioning

confidence: 99%

“…Third, there is an unknown mixture of gases constituting the base pressure in the apparatus mostly due to backflow through the turbo pump and vacuum chamber outgassing [38,39]. These background gases contribute a base loss rate, Γ bg , to which the test gas loss rate is added.…”

Section: Systematic Errorsmentioning

confidence: 99%

Realization of a universal quantum pressure standard

2020

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We report the realization of the first cold-atom primary standard. This standard is based on a universal law governing quantum diffractive collisions between particles that allows an experimental determination of the velocity averaged total collision cross section, the only parameter required to quantify the pressure or flux of particles given a sensor particle collision rate measurement. Using an ensemble of 87Rb sensor atoms, we show that this new quantum pressure standard can be applied to gases of both atomic (He, Ar, and Xe) and molecular species ( N 2 , C O 2 , and H 2 ), surpassing the scope of existing orifice flow pressure standards. We verify the accuracy of this new standard using an ionization gauge (IG) calibrated for N2 by an orifice flow standard. The gauge calibration factors determined by the cold atom and orifice flow standards differ by less than 0.5% and, thus, agree within their uncertainties of 2% and 2.8% respectively. Using this standard, we evaluate the response of two different IGs to a variety of different gas species and report variations of up to 20% for their measured calibration factors. We also observe a non-linear response of the IG readings for CO2 gas. Finally, we demonstrate the use of a magneto-optical trap (MOT) as a transfer standard to extend the measurement range by a factor of 100 to include pressures up to P ~ 10−5 Pa.

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“…Recently Akimichi et al succeeded in lowering the measurement range down to 10 −10 Pa, which isolates gas phase ions and ESD ions and then removes ESD ions with an energy filter [7][8][9]. The problem of H 2 outgassing in a stainless steel vacuum chamber has been known to be a serious obstacle in achieving XHV but it has not been fundamentally solved [10][11][12].…”

Section: Methodsmentioning

confidence: 99%

Generation of extremely high vacuum by ordinary procedures with a SUS304 vacuum chamber and total and partial pressure measurements by hot cathode ionization gauges and a quadrupole mass spectrometer

Hong¹,

Chung²,

Shin³

et al. 2005

Meas. Sci. Technol.

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The present study generated an extremely high vacuum of 10−10 Pa by very common methods such as using SUS304 chamber material, electropolishing surface treatment and turbomolecular pumping technology. We examined the gas phase and electron-stimulated desorption ions of the ion gauges, the effect of ambient temperature, total pressure and H2 partial pressure. One of the results showed that, as is well known, most of the residual gas in the extremely high vacuum chamber was H2 but there was also a little F, which is not so well known.

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Investigation of gas species in a stainless steel ultrahigh vacuum chamber with hot cathode ionization gauges

Cited by 8 publications

References 16 publications

Universality of quantum diffractive collisions and the quantum pressure standard

Universality of quantum diffractive collisions and the quantum pressure standard

Realization of a universal quantum pressure standard

Generation of extremely high vacuum by ordinary procedures with a SUS304 vacuum chamber and total and partial pressure measurements by hot cathode ionization gauges and a quadrupole mass spectrometer

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