Theorie und Praxis der Vakuumtechnik

Wutz, Max; Adam, Hermann; Walcher, Wilhelm

doi:10.1007/978-3-322-83543-7

Cited by 55 publications

(20 citation statements)

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“…In the transition region, the flow is generally considered unstable and assumed to potentially shift rapidly to a turbulent state [20,43]. The dynamics of turbulent transitions and the associated critical Re values for sustained turbulence in pipe flows are active fields of research.…”

Section: Gas Flows Through Pipesmentioning

confidence: 99%

Gas Flow Dynamics in Inlet Capillaries: Evidence for non Laminar Conditions

Wißdorf

Müller

Brachthäuser

et al. 2016

J. Am. Soc. Mass Spectrom.

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Abstract. In this work, the characteristics of gas flow in inlet capillaries are examined. Such inlet capillaries are widely used as a first flow restriction stage in commercial atmospheric pressure ionization mass spectrometers. Contrary to the common assumption, we consider the gas flow in typical glass inlet capillaries with 0.5 to 0.6 mm inner diameters and lengths about 20 cm as transitional or turbulent. The measured volume flow of the choked turbulent gas stream in such capillaries is 0.8 L·min −1 to 1.6 L·min −1 under typical operation conditions, which is in good agreement to theoretically calculated values. Likewise, the change of the volume flow in dependence of the pressure difference along the capillary agrees well with a theoretical model for turbulent conditions as well as with exemplary measurements of the static pressure inside the capillary channel. However, the results for the volume flow of heated glass and metal inlet capillaries are neither in agreement with turbulent nor with laminar models. The velocity profile of the neutral gas in a quartz capillary with an inner diameter similar to commercial inlet capillaries was experimentally determined with spatially resolved ion transfer time measurements. The determined gas velocity profiles do not contradict the turbulent character of the flow. Finally, inducing disturbances of the gas flow by placing obstacles in the capillary channel is found to not change the flow characteristics significantly. In combination the findings suggest that laminar conditions inside inlet capillaries are not a valid primary explanation for the observed high ion transparency of inlet capillaries under common operation conditions.

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Section: Gas Flows Through Pipesmentioning

confidence: 99%

Gas Flow Dynamics in Inlet Capillaries: Evidence for non Laminar Conditions

Wißdorf

Müller

Brachthäuser

et al. 2016

J. Am. Soc. Mass Spectrom.

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“…Pirani and Penning gauges are frequently used in vacuum measurements with a specified pressure ranges. These vacuum gauges have been in use since long time and the improvement in resolution, sensitivity of such sensors is still a subject of research [1]. Real time monitoring of vacuum has tremendous scope in this era of micro and emerging nano technology revolution, as most of these device fabrication processes need a clean and vacuum environment.…”

Section: Introductionmentioning

confidence: 99%

Fiber Bragg grating sensors for real-time monitoring of evacuation process

2009

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Fiber bragg grating (FBG) sensors have been widely used for number of sensing applications like temperature, pressure, acousto-ultrasonic, static and dynamic strain, refractive index change measurements and so on. Present work demonstrates the use of FBG sensors in in-situ measurement of vacuum process with simultaneous leak detection capability. Experiments were conducted in a bell jar vacuum chamber facilitated with conventional Pirani gauge for vacuum measurement. Three different experiments have been conducted to validate the performance of FBG sensor in monitoring vacuum creating process and air bleeding. The preliminary results of FBG sensors in vacuum monitoring have been compared with that of commercial Pirani gauge sensor. This novel technique offers a simple alternative to conventional method for real time monitoring of evacuation process. Proposed FBG based vacuum sensor has potential applications in vacuum systems involving hazardous environment such as chemical and gas plants, automobile industries, aeronautical establishments and leak monitoring in process industries, where the electrical or MEMS based sensors are prone to explosion and corrosion.

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“…As a starting condition we chose the implantation profile at T = T o and further the conditions at both interfaces at z = 0 and z = d: (10) n(d, t) = 0, (11) n(z, 0) = implantation profile of noble gas at T= T 0. (12) With these conditions, eq. (9) can be solved by separation of variables:…”

Section: Monotonous Heatingmentioning

confidence: 99%

“…Both RE and RD are proportional to the root of the mass m of the noble gas atom [12] and thus ~ ~/-m, see table 1. The quadrupole produces a voltage U proportional to the partial pressure p = aU+ b, so Ap =p-p~ = a(U-U~) and is fully determined without the constant a.…”

Section: The Pump Speed S V Is Given By 1/s V = 1~st + R E + R D ~ R mentioning

confidence: 99%

“…3 in the UHV system are shown schematically during the desorption measurements. Here the adsorption gas stream Oa is a function of the partial pressure p inside the system and the wall temperature T v, Qa =Pfa(Tv) [11,12] and the desorption gas stream Qd from the wall is only a function of the wall temperature, Qd =fd(Tv) [11,12]. The pump speed through the diaphragm is called S v. The relation between the gas stream Q from the sample and flux J is given by:…”

Section: Calibrationmentioning

confidence: 99%

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The desorption behaviour of implanted noble gases at low energy on silicon surfaces

Holtslag

Silfhout

1987

Surface Science

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Under UHV conditions, clean crystalline Si(lll) surfaces have been bombarded mass-selectively at room temperature with noble gas ions, Ne +, Ar +, Kr +, at normal incidence. By means of stepwise heating up to 1050 K the activation energies and desorbed doses of the noble gases have been straight forwardly determined as a function of temperature and bombardment dose. Firstly a short review of the kinetics of desorbed adsorbates is given and compared with a simple model for the desorption of particles embedded in a surface layer. This shows that the rate constant u in the latter case is orders of magnitude lower and are in agreement with obtained experimental values. From the obtained activation energies we have concluded that these values have to be explained by the silicon properties and that the influence of the noble gas is of second-order importance. The present method enables the simultaneous measurement of both the ellipsometric and desorption spectra during stepwise heating of the sample.

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Theorie und Praxis der Vakuumtechnik

Cited by 55 publications

References 0 publications

Gas Flow Dynamics in Inlet Capillaries: Evidence for non Laminar Conditions

Gas Flow Dynamics in Inlet Capillaries: Evidence for non Laminar Conditions

Fiber Bragg grating sensors for real-time monitoring of evacuation process

The desorption behaviour of implanted noble gases at low energy on silicon surfaces

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