The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Masahiro Hirata - One of the best experts on this subject based on the ideXlab platform.
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Calibration of ultrahigh Vacuum gauge from 10-9 Pa to 10-5 Pa by the two-stage flow-dividing system
Vacuum, 2011Co-Authors: Hajime Yoshida, Masahiro Hirata, Hitoshi AkimichiAbstract:Abstract A new two-stage flow-dividing system has been developed for the calibration of ultrahigh Vacuum Gauges from 10−9 Pa to 10−5 Pa for N2, Ar, and H2. This system is designed based on the techniques for our previously developed calibration system in the range from 10−7 Pa to 10−2 Pa. Three modifications were performed to extend the calibration pressure to a lower range. The relative standard uncertainty of the generated pressure (k = 1) is in the range from 2.3% to 2.6%, from 10−9 Pa to 10−5 Pa. The characteristics of ultrahigh Vacuum Gauges were also examined by using this system. The stabilities of the pressure reading, the linearity, the temperature dependence, and the long-term stability were examined. These results show that the calibration of ultrahigh Vacuum Gauges is possible in the range from 10−9 Pa to 10−5 Pa for N2, Ar, and H2 with the uncertainty of about 6.0% (k = 2) by this new system.
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Two-stage flow-dividing system for the calibration of Vacuum Gauges
Journal of Vacuum Science and Technology, 2008Co-Authors: Hajime Yoshida, Kenta Arai, Hitoshi Akimichi, Masahiro HirataAbstract:A two-stage flow-dividing system was developed for calibrating an ionization gauge (IG) and residual gas analyzer (RGA). This system generates a stable high and ultrahigh Vacuum from 8×10−3to2×10−7Pa by adjusting the pressure in the first chamber using N2, Ar, He, and H2. The calibration pressure in the third chamber is calculated from the pressure in the second chamber using their linear relation in molecular flow. The uncertainty of the generated pressure was comparable to or several times larger than that of the continuous-expansion system. However, this system has a simple configuration and is easy to operate compared with the continuous-expansion system because it has no moving parts. Results of the calibration of IG and RGA showed that the two-stage flow-dividing system is useful for a routine calibration of practical Vacuum Gauges in high and ultrahigh Vacuum.
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dsmc analysis of thermal transpiration of capacitance diaphragm gauge
Vacuum, 2002Co-Authors: Shinichi Nishizawa, Masahiro HirataAbstract:Abstract The capacitance diaphragm gauge (CDG) is one of the most important Vacuum Gauges in low and medium Vacuum ranges. CDG has a non-linear sensitivity below 100 Pa because of the temperature difference between the sensor head and the Vacuum chamber, which is called thermal transpiration. This sensitivity depends on gas species and pressure. In this study, by using a direct simulation Monte Carlo (DSMC) method, pressure distribution in the connecting tube of the gauge was obtained under the pressure range from molecular flow regime to viscous flow regime (10 −2 –10 2 Pa) taking account of the temperature distribution along the connecting tube. Furthermore, the pressure dependence of the sensitivity of the CDG was derived from the pressure difference between the hot and cold ends, and found to be in good agreement with the pressure dependence of sensitivity obtained by an empirical equation. The influence of gas–surface interaction on the thermal transpiration was also analyzed.
Karl Jousten - One of the best experts on this subject based on the ideXlab platform.
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A standard to test the dynamics of Vacuum Gauges in the millisecond range
Vacuum, 2014Co-Authors: Karl Jousten, Sarantis Pantazis, Joachim Buthig, Regine Model, Martin Wüest, Jaroslaw IwickiAbstract:Abstract Vacuum Gauges that control fast processes in industrial applications, e.g. load locks, should immediately react to pressure changes. To study the response time of Vacuum Gauges to rapid pressure changes, a dynamic Vacuum standard was developed where the pressure may change from 100 kPa to 100 Pa within 20 ms in a step-wise manner or within longer times up to 1 s in a predictable manner. This is accomplished by a very fast opening gate valve DN40 and exchangeable orifices and ducts through which the mass flow rate can be calculated by gas flow simulation software. A simple physical model can be used to approximate the calculations. Experiments have been performed with capacitance diaphragm Gauges with improved electronics to give a read-out every 0.7 ms. Preliminary results indicate that their response time is at most 1.7 ms, but may be significantly less.
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On the gas species dependence of Pirani Vacuum Gauges
Journal of Vacuum Science and Technology, 2008Co-Authors: Karl JoustenAbstract:The dependence of the readings of four different Pirani Vacuum Gauges on nine different gas species was investigated. It was found that the gas species dependence varied from gauge to gauge so that in general only an approximate correction factor for a specific gas species can be given for this type of Vacuum gauge. A Pirani gauge produced by microstructuring methods showed a broader measurement range than conventionally produced Gauges. By comparing experimental with theoretical data, it was possible to give upper limits of the thermal accommodation coefficients of the nine gas species on the technical surfaces of oxidized tungsten and silicon within the Gauges.
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Gauges for fine and high Vacuum
2007Co-Authors: Karl JoustenAbstract:Vacuum Gauges for use in accelerators have to cover about 17 decades of pressure, from 10 Pa to 10 Pa. In this article we describe the history, measurement mode, design, accuracy and calibration of the Gauges used down to 10 Pa. We focus on commercially available types of Gauges, i.e., mechanical Gauges, piezoresistive and capacitance diaphragm Gauges, thermal conductivity Gauges, and spinning rotor Gauges.
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ultrahigh Vacuum Gauges
2007Co-Authors: Karl JoustenAbstract:Ionization Gauges exclusively are used for ultrahigh Vacuum. After a brief history, the design, use, and accuracy of ionization Gauges will be described in this article.
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Temperature corrections for the calibration of Vacuum Gauges
Vacuum, 1998Co-Authors: Karl JoustenAbstract:Abstract Commercial Vacuum Gauges indicate pressure, although their signal is often generated proportional to other quantities of the gas like the volume density or the impingement rate of gas molecules. These different types of Gauges exhibit different mathematical dependences on temperature. To compare calibration results and to use gauge readings properly, it is necessary to refer the calibration results to an agreed reference temperature, which is normally 23 °C. This report deduces the relevant equations to do the corrections properly when Gauges, which are in use as secondary standards (ionisation Gauges, spinning rotor Gauges, capacitance diaphragm Gauges), are being calibrated or used at temperatures different from the agreed reference temperature.
V. V. Kuz'min - One of the best experts on this subject based on the ideXlab platform.
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New Method of Testing Vacuum Gauges
Measurement Techniques, 2004Co-Authors: V. V. Kuz'minAbstract:A new original method for testing Vacuum Gauges is presented. It consists of two stages: in the first stage gas is continuously fed into a measurement chamber and in the second stage it is pumped out (in the same pressure range). By simultaneously solving the equations describing both stages, errors caused by secondary gasdynamic processes are eliminated and there is an increase in the overall accuracy of the testing.
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Autonomous system for calibration of Vacuum
Measurement Techniques, 1997Co-Authors: V. V. Kuz'minAbstract:We describe a new design for a Vacuum system that makes it possible to calibrate Vacuum Gauges that can operate without regular replenishment of calibration gasses, as in aircraft. We present a computation for the system that is based on real operational conditions.
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A new dynamic technique for the calibration of Vacuum Gauges (doubling principle)
Vacuum, 1996Co-Authors: V. V. Kuz'minAbstract:A new dynamic technique for the calibration of Vacuum Gauges is described. It does away with the limitations of the gas flow regime and, due to that, the calibration range is extended in the direction of high pressures. The technique is based on the addition of the known gas flow rate with the other gas flow rate, equal to the known one, that is established by the identity of corresponding Vacuum gauge readings, and on the following cyclic adjustment of the gas flow rate through a leak and a constant inlet element. As a result, a sequence of pressure values is reproduced in a calibration chamber, each subsequent pressure being two times higher than the proceeding one (doubling principle). The examples of the application of this technique using a reduction (dynamic expansion) calibration arrangement, are given.
Hajime Yoshida - One of the best experts on this subject based on the ideXlab platform.
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newly developed standard conductance element for in situ calibration of high Vacuum Gauges
Measurement, 2012Co-Authors: Hajime Yoshida, Kenta Arai, Hitoshi Akimichi, Tokihiko KobataAbstract:Abstract A new leak element, which is named as “standard conductance element (SCE)”, has been developed for in situ calibration of ionization Gauges (IGs) and quadrupole mass spectrometers (QMSs). The SCE is made of a stainless-steel sintered filter with the pore size of less than 1 μm. Since the gas flow through the SCE satisfies the molecular flow condition even at the pressure up to 10 4 Pa, some useful characteristics of molecular flow are available. The SCE is supplied to users with a calibration certificate described its molecular conductance. Users can introduce optional test gases with the known flow rate to their Vacuum chamber through the SCE in their laboratories. The overview of the SCE, the calibration method and recommended practices are introduced.
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Calibration of ultrahigh Vacuum gauge from 10-9 Pa to 10-5 Pa by the two-stage flow-dividing system
Vacuum, 2011Co-Authors: Hajime Yoshida, Masahiro Hirata, Hitoshi AkimichiAbstract:Abstract A new two-stage flow-dividing system has been developed for the calibration of ultrahigh Vacuum Gauges from 10−9 Pa to 10−5 Pa for N2, Ar, and H2. This system is designed based on the techniques for our previously developed calibration system in the range from 10−7 Pa to 10−2 Pa. Three modifications were performed to extend the calibration pressure to a lower range. The relative standard uncertainty of the generated pressure (k = 1) is in the range from 2.3% to 2.6%, from 10−9 Pa to 10−5 Pa. The characteristics of ultrahigh Vacuum Gauges were also examined by using this system. The stabilities of the pressure reading, the linearity, the temperature dependence, and the long-term stability were examined. These results show that the calibration of ultrahigh Vacuum Gauges is possible in the range from 10−9 Pa to 10−5 Pa for N2, Ar, and H2 with the uncertainty of about 6.0% (k = 2) by this new system.
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Two-stage flow-dividing system for the calibration of Vacuum Gauges
Journal of Vacuum Science and Technology, 2008Co-Authors: Hajime Yoshida, Kenta Arai, Hitoshi Akimichi, Masahiro HirataAbstract:A two-stage flow-dividing system was developed for calibrating an ionization gauge (IG) and residual gas analyzer (RGA). This system generates a stable high and ultrahigh Vacuum from 8×10−3to2×10−7Pa by adjusting the pressure in the first chamber using N2, Ar, He, and H2. The calibration pressure in the third chamber is calculated from the pressure in the second chamber using their linear relation in molecular flow. The uncertainty of the generated pressure was comparable to or several times larger than that of the continuous-expansion system. However, this system has a simple configuration and is easy to operate compared with the continuous-expansion system because it has no moving parts. Results of the calibration of IG and RGA showed that the two-stage flow-dividing system is useful for a routine calibration of practical Vacuum Gauges in high and ultrahigh Vacuum.
Hitoshi Akimichi - One of the best experts on this subject based on the ideXlab platform.
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newly developed standard conductance element for in situ calibration of high Vacuum Gauges
Measurement, 2012Co-Authors: Hajime Yoshida, Kenta Arai, Hitoshi Akimichi, Tokihiko KobataAbstract:Abstract A new leak element, which is named as “standard conductance element (SCE)”, has been developed for in situ calibration of ionization Gauges (IGs) and quadrupole mass spectrometers (QMSs). The SCE is made of a stainless-steel sintered filter with the pore size of less than 1 μm. Since the gas flow through the SCE satisfies the molecular flow condition even at the pressure up to 10 4 Pa, some useful characteristics of molecular flow are available. The SCE is supplied to users with a calibration certificate described its molecular conductance. Users can introduce optional test gases with the known flow rate to their Vacuum chamber through the SCE in their laboratories. The overview of the SCE, the calibration method and recommended practices are introduced.
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Calibration of ultrahigh Vacuum gauge from 10-9 Pa to 10-5 Pa by the two-stage flow-dividing system
Vacuum, 2011Co-Authors: Hajime Yoshida, Masahiro Hirata, Hitoshi AkimichiAbstract:Abstract A new two-stage flow-dividing system has been developed for the calibration of ultrahigh Vacuum Gauges from 10−9 Pa to 10−5 Pa for N2, Ar, and H2. This system is designed based on the techniques for our previously developed calibration system in the range from 10−7 Pa to 10−2 Pa. Three modifications were performed to extend the calibration pressure to a lower range. The relative standard uncertainty of the generated pressure (k = 1) is in the range from 2.3% to 2.6%, from 10−9 Pa to 10−5 Pa. The characteristics of ultrahigh Vacuum Gauges were also examined by using this system. The stabilities of the pressure reading, the linearity, the temperature dependence, and the long-term stability were examined. These results show that the calibration of ultrahigh Vacuum Gauges is possible in the range from 10−9 Pa to 10−5 Pa for N2, Ar, and H2 with the uncertainty of about 6.0% (k = 2) by this new system.
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Two-stage flow-dividing system for the calibration of Vacuum Gauges
Journal of Vacuum Science and Technology, 2008Co-Authors: Hajime Yoshida, Kenta Arai, Hitoshi Akimichi, Masahiro HirataAbstract:A two-stage flow-dividing system was developed for calibrating an ionization gauge (IG) and residual gas analyzer (RGA). This system generates a stable high and ultrahigh Vacuum from 8×10−3to2×10−7Pa by adjusting the pressure in the first chamber using N2, Ar, He, and H2. The calibration pressure in the third chamber is calculated from the pressure in the second chamber using their linear relation in molecular flow. The uncertainty of the generated pressure was comparable to or several times larger than that of the continuous-expansion system. However, this system has a simple configuration and is easy to operate compared with the continuous-expansion system because it has no moving parts. Results of the calibration of IG and RGA showed that the two-stage flow-dividing system is useful for a routine calibration of practical Vacuum Gauges in high and ultrahigh Vacuum.